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REPORT NO. 46 The Evaporites of the Upper Ordovician Strata in the Northern Part of the Williston Basin by D. M. KENT 1960 DEPARTMENT OF MINERAL RESOURCES Geological Sciences Branch Sedimentary Geology Division A summary of this report was read before a meeting of the Saskatchewan Geological Society, Regina, Saskatchewan, September 29th, 1959. ABSTRACT As a result of epeirogenic movements of the basin and surrounding metastable shelf areas, the Upper Ordovician sediments of the northern part of the Williston Basin are composed of four depositional cycles, each of which contains an evaporitic sequence. Each cycle consists of five phases, each phase being represented by a specific lithology: 1. fossiliferous fragmental limestone 2. argillaceous dolomite 3. anhydrite 2. argillaceous dolomite I. fossiliferous fragmental limestone. The evaporites are considered to be primary and were laid down as intra.. basin deposits due to a restriction of circulation in the northern part of the Williston Basin. A shoal region towards the open sea formed a physical barrier to circulation, and a dynamic barrier developed between the denser saline brine in the evaporating basin and the less dense, near shore, waters provided restriction on the landward side. The evaporitic basin reached its maximum areal extent when the " A" Evaporite of the Herald Member was laid down. After that time, the limits of the evaporite basins did not extend much beyond the Inter .. national Boundary area of Saskatchewan and North Dakota. Stratigraphic traps, consisting of a porous fades overlain by an impervious layer such as the evaporite deposits, probably form the best reservoirs for the accumulation of hydrocarbons'. Where the evaporites overlie radial domes or pitching anticlines, and the facies is favourable, oil may also be accumulated. Oil accumulations may be present along tectonic hinge lines, to which the absence of Middle Devonian Prairie Evaporites is thought also to be indirectly related. TABLE OF CONTENTS Page ABSTRACT ..................... ..... . LIST OF ILLUSTRATIONS 3 . ·························. 5 ACKNOWLEDGMENTS .. 7 INTRODUCTION ............ . 8 GENERAL STRATIGRAPHY ... 10 Origin of Stratigraphic Nomenclature........................................ ........... .... .10 Outcrop Nomenclature......................................................................................... .... 10 Subsurface Nomenclature and Correlation Criteria .........................10 Red River Formation ....................................................................................................... .12 Yeoman Member ............................................................................................................ 12 Herald Member........................ . ......... .... ... .............. ... ....................... .............. 13 Oolitic Limestones .................................................................... ...................... 15 Argillaceous Dolomites ...................................................................................... 15 Evaporites........................................................................................................ 17 Fossiliferous Fragmental Limestones .................................................. 18 Stony Mountain Formation.......................... ............................................................... 20 Stoughton Member .............................. .....................................................................20 Shale fades .. .................... ...................... .. ........................................................ 20 Carbonate facies .........................................................................................................20 Gunton Member .......................................................................................................... 21 Gunton Evaporite ........................................................................................21 Stonewall Formation....................................................................................................................22 Stonewall Evaporite .......................................................................................22 PETROLOGY OF THE ANHYDRITES AND EVAPORITIC DOLOMITES........................ 24 The Origin of the Anhydrites ............................................................................................ 24 Secondary Anhydrite....................................................................................................................26 Evaporitic Dolomites..................................................................................................................28 STRUCTURE .........................................................................................................................................................32 SEDIMENTATION .............................................................................................................................................35 Depositional Environment......................................................................................................35 Evaporitic Cycles..............................................................................................................................38 PETROLEUM PROSPECTS ........................................................................................................................... 39 BIBLIOGRAPHY ................................................................................................................................................ 41 APPENDIX .................. .......................................................................................................................................... 43 LIST OF ILLUSTRATIONS Tables Table 1 Table 2 Figures Figure I Figure 2 Page Upper Ordovician Nomencl ature .... ......... 12 Shows relationship between phases of the evaporitic cycles, the lithologies a nd tectonic movements .. . . ... 38 Key Map .. 8 Characteristic Section of Upper Ordovician Strata in the Southeast Corner of Saskatchewan. Gamma ray and neutron curves from logs of the Imperial Silverton No. 3, 18 well (Lsd 3-18,3,32wl, Saskatchewan ). Lithology from cutting samples and cored sections of several wells in the southeast portion of the area of study . 14 Figure 3 Characteristic Section of Upper Ordovician Strata of the International Boundary Area, Saskatch ewan. Gamma ray and Neutron curves from logs of the Imperial Herald No. 1,31 well (Lsd 1,3 I, 1-20w2, Saskatchewan ). Lithology from several cored sections in the International Boundary Area of southeastern Saskatchewan ... . .... ...... ............ ......16 Figure 4 East, West Stratigraphic Cross Section (Section A-A' ) of Upper Ordovicia n Strata from the British American Baciu No. 15-36 well (Lsd 15,36,6-9w3 ) to the Socony Western Prairie Imperial Carievale No. I well (Lsd 16-4-3,32wl ). ( In Pocket ) Figure 5 North-South Stratigraphic Cross Section (Section B-B ' ) of Upper Ordovician Strata from the Tidewater Bladworth Crown No. 1 well (Lsd 16,36,17,29w2 ) to the Imperia l . . (In Pock et ) Herald No. 1-31 well (Lsd 1-3 1-1-20w2 ) Figure 6 North-South Stratigraphic Cross Section (Section C-C 1 ) of Upper Ordovician Strata from the Canadian Gulf Margo No. 8, 11 well (Lsd 8, l 1-33,9w2 ) to the Imperial Silverton No.3,18well (Lsd3, 18,3,32wl )...... .... ..... ( In Pocket ) Figure 7 Projected Panel Diagram of Herald Member ....... (In Pocket ) Figure 8 Structure Contour Map on Top of the Yeoman M ember .... 33 Figure 9 Tectonic Map of the Prairie Provinces and Northwestern United States illustrating the positive and negative ele, ments (After Borden, 1956 ) and the maximum area covered by evaporite deposits during Red River times..... ........... .34 Figure IO Generalized section through the region of study illustrating the sedimentary environments present during the time when the "A" Evaporite of the Herald Member was deposited ......... 36 Figure 11 Tectonic Map of the Prairie Provinces and Northwestern United States illustrating the positive and negative ele, ments (After Borden, 1956 ) and the distribution of the evaporitic basins during Gunton,Stonewall times... .........37 LIST OF ILLUSTRATIONS- (Continued ) Plates Page Plate I ....23 Plate 2 .... 25 Plate 3 ...... 27 Plate 4 ............. . ......29 Plate 5............. . . ... JO ACKNOWLEDGMENTS The writer wishes to acknowledge the generous assistance and constructive criticisms rendered him by his colleague~· in the Department of Mineral Resources and theco,operation of the staff of the Department of Geology, University of Saskatchewan, who permitted the author the use of their special equipment to take the photomicrographs used in the text. INTRODUCTION The increased interest in recent years in the possible oil producing horizons of the Lower Palaeozoic strata of southern Saskatchewan has made a better understanding of the stratigraphy and sedimentation of these rocks desirable. The presence of evaporitic deposits in the Upper Ordovician rocks gives rise to the possibility of reservoir conditions similar to those found in the Mississippian strata of southeastern Sask, atchewan. In the latter both primary and secondary anhydrites form excellent reservoir cap rocks. The purpose of this paper is to study the stratigraphy of the evaporites of the Upper ·Ordovician, their areal dis, tribution and their relationship to possible oil reservoirs. The area covered by this report consists of that part of southern Saskatchewan within the - Williston Basin which is underla\n by the KEY MAP .,--·-·- - - --~ / I I ·- ·- \ HUDSON 8Ar I I i i I i i / I I i i I i i i i i MANITOBA ·, I \ i I SASKATCHEWAN / ,- / i / / / ,- i \I SASK ATOON·'· \; . . \ ~1~ BRA~OON ~~L \ '5.-;-·· - .IL.L/STO~ --BASIN~··\~·- MONTANA '<..'<. '<.. HELE N4. \..'\ ; i WIN~IPE·G·_ .. _j _ .. _. ,- \ \ 1 i '<. \ I \ ij _ ___NORTH DAKOTA _.j , _ . ../. _ - --· - ·-· - · I \ \ I -- ·- - ·- -- - - - - ~{......._ _,,,sfTH DAKOTA l~-~--j i j j j j ----i ~ \ i i i ,-·-·-·- i t- i WYOMING ~ ' ·: -J· - · .... . ~\, - ) I ,oo 100 Repo,t Ano SCALE IN MILES Nole:- Willlston Basin boundary is ofter Porter ond Fuller (1959) Figure 1- Map of Williston Basin region showing area of study. 8 evaporites of Upper Ordovician age (Figure l ). It is bounded on the east by the Manitoba / Saskatchewan Interprovincial boundary, on the west by the 108th meridian of longitude, on the south by the International boundary and on the north by the 52nd meridian of latitude. The rocks pertinent to this study occupy approximately the middle portion of a 1400 foot succession of Silurian and Upper Ordovician car; bonates and evaporites. The sequence studied attains a maximum thick; ness of 335 feet within the report area and includes only those rocks of Upper Ordovician age that contain evaporitic deposits. The report area includes about 90 deep wells which have penetrated Ordovician or deeper strata. However, only 14 of these wells were cored in Upper Ordovician beds. Sample cuttings and mechanical logs are available for all wells. All the cored intervals pertinent to this study were examined together with samples from another 50 wells. Sixty thin sec; tions of the anhydrite and associated rocks were made and were found to be invaluable aids in investigation of the sedimentation and diagenesis of the rocks. 9 GENERAL STRATIGRAPHY ORIGIN OF STRATIGRAPHIC NOMENCLATURE Outcrop Nomenclature The Ordovician System in Western Canada was first described by Dowling (1900) from the outcrops of Manitoba. He subdivided these rocks into five units, in descending order: Stony Mountain Formation Upper Mottled limestone Cathead limestone Lower Mottled limestone Winnipeg sandstone. Dowling's classification was used for many years, but in 1928 and again in 1929 Foerste, who did considerable work on the fauna of the Ordovician strata of the Arctic and Subarctic regions, suggested that the fauna of Dowling's middle three units very closely resembled the Galena phase of the Trenton limestone, as exposed in the Upper Mississippi Valley. For this reason he proposed the collective name, Red River Formation, to include all three units and added the name Selkirk limestone for the Upper Mottled limestone and Doghead limestone for the Lower Mottled limestone. In 1943 Okulitch worked on the Stony Mountain Formation in the outcrops of Manitoba. He set up a four-fold classification of that formation, based largely-on faunal evidence. His four units were, from top to bottom: Birse Member Gunton Member Penitentiary Member Stony Mountain Shale Member. Baillie produced a detailed study of the Manitoba outcrop rocks in 1952. He relied on Foerste's classification of the carbonate rocks immediately overlying the Winnipeg sandstone, but he found that a three-fold classi, fication of the Stony Mountain Formation was more workable, since he was unable to distinguish Okulitch's Birse Member from the Gunton Member and included the former in the latter. Until 1953 the Stonewall Formation (which overlies the Stony Mountain Formation ) was generally thought to be Silurian in age, but Stearn (1953 ) in a paper presented to the Geological Society of America in Toronto, Ontario, suggested that the fauna of this formation was of Upper Ordovician age. Later, in 1956, he published further faunal evi, dence supporting his conclusions. Subsurface Nomenclature and Correlation Criteria The first subsurface study of the Ordovician rocks of the Williston Basin and adjacent areas was carried out by Rader (1952) in the central portion of the Williston Basin. He made little attempt at correlation with the strata of the Manitoba outcrops, and based his subdivisions on lithologic differences and mechanical log characteristics. This resulted in the inclusion of the Gunton Member of the Stony Mountain Formation in the overlying Interlake Group and the insertion of the Penitentiary Member of the same formation in the Stony Mountain Shale Member. Rader also subdivided the Red River into two units, a lower normal 10 marine unit and an upper evaporitic unit. The lower unit was considered equivalent to the combined Doghead and Cathead limestones, while the upper one was thought to be equivalent to the Selkirk limestones. In 1953 Rader carried the same subdivisions of the Upper Ordovician rocks into northeastern Montana. Other subsurface studies were performed by Ower ( 1953 ) in southwestern Manitoba, Stanton ( 1953 ) in western Saskatchewan, and Ross ( 1957 ) in eastern Montana. In all cases a three, fold classification of the Ordovician rocks was followed: Stony Mountain Formation Red River Formation Winnipeg Formation. Ower attempted to correlate the subsurface with the surface exposures. He found that the Red River of southwestern Manitoba could not be subdivided and that the Penitentiary Member could not be distinguished in the subsurface. Stanton found a parallel between the Ordovician sediments of his area and those studied by Rader. He, too, subdivided the Red River into two units with lithologic characteristics similar to the units proposed by Rader. Both Stanton and Ower included the lower part of the Stonewall Formation, as now picked, in the Stony Mountain Formation. Ross (1957 ) also assigned the Stonewall Formation to the Stony Mountain Formation and placed all the sediments from the top of his Stony Mountain Formation to the base of the Red River Formation in the Big Horn Group. In the spring of 1958 Porter and Fuller presented a paper entitled "Lower Palaeozoic Rocks of the Northern Williston Basin and Adjacent Areas" to the Second International Williston Basin Symposium in Regina, Saskatchewan. This paper was later published in the January 1959 issue of the bulletin of the American Association of Petroleum Geologists and also in the Symposium Volume. It was the first published, comprehensive subsurface study of the pre-Devonian strata in Saskatchewan. In this paper Porter and Fuller found a close correspondence between widespread non-sequential arenaceous and argillaceous beds observed in the sub, surface and beds of similar lithologies that mark the formation boundaries in the outcrops. They were of the opinion that these non-sequential beds were the result of temporary interruptions in carbonate deposition of great areal extent, and that they represented para-time markers. Porter and Fuller initiated a four-fold classification of the Ordovician rocks, (Table 1) as they included the Stonewall Formation in the strata of this age, following the suggestion of Stearn (1953, 1956 ). The Penitentiary Member was again found to be indistinguishable in the subsurface and was included in the Stony Mountain Shale, while the Red River was subdivided into a lower and an upper unit similar to those proposed by Rader (1952, 1953) and Stanton (1953 ). Following the work of Porter and Fuller the Saskatchewan Geological Society set up a Lower Palaeozoic Names and Correlation Committee with the object of standardizing the nomenclature, choosing type sections and publishing these together with stratigraphic cross sections illustrating correlations of the Lower Palaeozoic strata. The committee retained the Note: Since this manuscript was completed, a comprehensive paper by J. M. Andrichuk• entitled "Ordovician and Silurian Stratigraphy and Sedimentation in Southern Manitoba, Canada," was published (Bull. Amer. Assoc. Petrol. Geo!., Vol. 43, No. 10, pp. 2333-2398) . The conclusions reached by the present author are in general agreement with those of Andrichuk. 11 TABLE I NOMENCLATURE OF PART OF THE UPPER ORDOVICIAN OF SOUTHERN SASKATCHEWAN PORTER SASK. GEOLOGICAL SOCIETY STONEWALL ::::, 0 a: '-" _, _, <t 0 z >- I- z Gunton Beds a, Stoughton Beds I:? "' a: UJ >"' Herold Beds a:~ O UJ a: a, ; z '-" i z z ~ a: 0 :c '-" ;;; >- a: 0 I- Gunton Member 0 0 :E a: O O :E UJ >- Q. ::::, 0 V) z REPORT STONEWALL FORMATION z ~ ::::, THIS FULLER STONEWALL FORMATION BEDS z Q. AND (1959) (1958) V) Stony Mountoln Shale ond Lateral Equivolents Upper Red River Table 1- O a: a: O LL ,'! z z z ~ LL a: 0 !::? a, 2 Member :E a: 0 Stoughton Member IV) a: z UJ ~ a: Lower Red River .. ;:: '-" Gunlon 0 a: ::::, 0 :c a: z UJ O > UJ ::::, 0 a:~ Yeomon Beds 3!, Q. Herold Member 0 ~ :E 0 a: a: ~ UJ Yeoman Member Upper Ordovician Nomenclature. unit boundaries established by Porter and Fuller, but appl ied the names "Yeoman" and "Herald" to their Lower and Upper Red River units. They also gave the name Stoughton Beds to the Stony Mountain Shale and equivalents (Table I ). Other changes included the application of names to Porter and Fuller's marker defined units in the Interlake Group and the introduction of the term "Beds" for these . para-time marker defined units. The term "Beds" was previously used to describe para-time marker defined units in the Mississippian System in southeastern Saskatchewan. In these strata there is a marked discordance between the lithologic units (magnafacies of Caster, 1934 ) and the stratigraphic units as defined by para-time marker beds. The term "Beds" may also be applicable to the stratigraphic units of the Lower Palaeozoic rocks, but the discordance between magnafacies and marker defined units is more subtle and within certain ?teas, the markers also separate different lithologies. In this case, the terms Formation and Member could also be applied to the stratigraphic units. In the area covered by this report the markers separate different lithologies, also some of the units within the area of study may be subdivided into smaller local units. Since a hierarchy of stratigraphic units is not provided for by the use of the term "Beds," the author concluded that Formation and Member were more applicable in the report area, therefore, the terminology as presented in Table 1 is proposed for these strata. RED RIVER FORMATION Within the area of this report the Red River Formation is divisible on lithological grounds into two major units, the Yeoman Member and the Herald Member. The lithologies of these two members reflect dif, ferent environments of deposition, and therefore the divisions may also be considered to be based on depositional environments. Yeoman Member The Yeoman Member is the lower division of the Red River Forma, 12 lion. The rocks compnsmg this unit underlie the entire area of study and range from about 350 feet thick in the southeast part of the area to about 140 feet at the northern and western limits of the map area. The rocks of the Yeoman Member in the region of this report consist mostly of dolomitized, mottled, fossiliferous,fragmental limestones. The colour of the mottling ranges from tan to light brown. The fossil fragments are often in a poor state of preservation due to the effects of dolomitiza, rion, while original textures have been affected also by this process. The mottling is a characteristic feature of this unit and is in the form of irregularly branching structures of a dense, tan, microcrystalline•, dolomite. The interstices in these structures are occupied by light brown carbonate with a sucrosic, microcrystalline texture and intergranular porosity. Towards the northern and western limits of the report area, the rocks of the Yeoman Member become increasingly dolomitic and consist of tan, microcrystalline, very dolomitic limestone, or dolomite, with some poorly preserved fossils. The lower boundary of this member (the base of the Red River Formation ) is represented by a marked change to carbonate rocks from the elastic rocks of the underlying Winnipeg Formation. The upper contact of this member has been established by the author at the base of an argillaceous dolomite horizon which underlies the lower evaporite of the overlying Herald Member. In the southeastern portion of the report area, the argillaceous dolomite is not present and the upper contact of the Yeoman Member is then based on a lithological change from fossili, ferous fragmental limestones to oolitic limestones. The choice of the upper contact is different from that of Porter and Fuller (1959 ) and the Sask, atchewan Geological Society (1958 ) who both chose the top of the argillaceous dolomites. The alteration was made because the writer was of the opinion that the argillaceous dolomites in question belong more properly with the overlying evaporite sequence than with the underlying dolomitized fossiliferous limestones. They appear to have been laid down under conditions similar to the "earthy textured dolomites" of Edie (1958), which underlie the anhydrites in the Mississippian rocks of south, east Saskatchewan, and which he considers to be part of the deposits of a lagoonal environment where the Mississippian anhydrites were precip, itated. The Saskatchewan Geological Society ( 1958) established Shell Yeoman No. 6-32 (Lsd 6, Sec. 32, Twp. 8, Rge. 16, w2M ) as the type well of the Yeoman Beds. The top of the Yeoman Member, in this well, as picked by the writer is at 8038 feet below the kelly bushing (elevation 1926 feet ). Herald Member The Herald Member conformably overlies the Yeoman Member. It has an overall thickness of 120 feet in the southeastern portion of the area thinning to 50 feet along the western edge, to 35 feet in the northwest and to 30 feet in the northeast parts of the region of study. The Herald Member comprises several smaller lithologic units including oolitic limestones, argillaceous dolomites, evaporites and dolomitized fossilifer, ous fragmental limestones (FigurPS 2 and 3 ). I In the sense of Williams, Turner and Gilbert (1955, pp.276-277) . Their classification of non-elastic textures and grain sizes is as follows: Crystalline Granular-Coarse greater than 5 mm. - Medium 1-5 mm. - Fine less than 1 mm. Microcrystalline 0.01 mm.,0.2 mm. Cryptocrystalline less than O.IJI mm. 13 IMPERIAL SILVERTON No. 3-18 L.a.d 3-18-3-32 WPM lll.1139 z HEUTl'ION GAMMA !IAY <{ l._ - a:: c-·- · :::> { _J ~ -Cf) ):_ ~ ? ,:~ ·--s STONEWALL FORMATIO N I STONEWALL z <{ - 0 > 0 0 a:: ~- ~- 0 ~ :;; GUN TON ....-,r MEMBER ~> \ 0:: 0 "- \ .... z i!z z ::, Oer >-w 0 :,: al 0 a:: z>- g~ 0 Ii; "' w Q_ I r z :;; Q_ E...~ITE < ;'., -.,.-;, :r.;:-- <.!) ~ =>w z 0 ti :::> :;; 0:: 0 FOSSILIFEROUS er w FRAGMENTAL ~ LIMESTONES al w ~ "- 0 ...J 0:: er w w cc> SHALE ct :,:: 0:: i\.._ l' ...t-~ ~ OOLITIC LIMESTONES Cl w FACIE YEOMAN MEMBER ....~~ f I. 1 CHARAC TERISTIC SECTION OF UPPER ORDOVICIAN STRATA IN THE SOUTHEAST CORNER OF m[. . . ~" o..,,.," ~"'9illt:,QI01110oior!w!H GI) ~ DtkwMoc L_,...,.... mOolofflitiCSl!ctl11 m °"°""'" ~ OoiCllftW,c Llffit.a-1 •.•,• r"'*........, r'°9M"f1 ~w Sano t,o- • 11 Anllyoritt llltllf ltlld wpl'i,ttcrytll Ol161u '"'°""" Ptlltrt SASKATCHEWAN ~ c...~S/'lot. FIG. 2 Flcure 2-Characterlstlo Section of Upper Ordovician Strata In the Southeaat Corner of Saskatch ewan. Gamma ray and Neutron curves from lop of the Imperial Silverton No. 8·18 well (Lsd 3-18-3-82w1, Saskatchewan) . Litholocy from cuttlnc samples and cored sections of several wells In the southeast portion of the area of study. 14 Oolitic Limestones- The oolitic limestone deposits of the Herald Member have a north-northeasterly trend along the eastern edge of the area of study. They underlie a region along the Manitoba / Saskatchewan Interprovincial Boundary limited by Range 2 west of the second meridian on the west, and probably extend eastward into Manitoba and southward across the International Boundary into North Dakota. (Figure 8 and 9 ). The thickest section of oolitic limestones was observed in the sample cuttings of the Imperial Silverton No. 3, 18 well (Lsd 3, Sec. 18, Twp. 3, Rge. 32, wlM ) (Fig. 2 ). Sixty-nine feet of oolitic limestones were encountered between the intervals 7531 feet and 7600 feet below kelly bushing. Northward and westward from this well the oolitic limestones gradually thin and die out (Figure 4 and 6 ). Micro-oolites, oolites and pseudo-oolites (No. 1 Plate 1) are the major constituents of these rocks along with some crinoid ossicles and brachio, pod remains. The oolities and pseudo-oolites range from 0.08 mm. to 0.7 mm. long, along their major axis; the average is about 0.25 mm. The matrix of the rock consists of cryptocrystalline' dolomite with irregularly shaped grains (No. 2 Plate 1). Occasionally, however, the space between the oolites is infilled by cryptocrystalline anhydrite in the form of ir, regularly shaped crystals (No. 1 Plate 1). Pieces of dolomitic material, which appear to be corroded remnants of the original matrix, are often isolated in the anhydrite. Where dolomite infills the interstices between the oolites elongated euhedral crystals of anhydrite have been observed cutting through the oolites (No. 2 Plate 1). The pseudo,oolites have no concentric interior structure, they are often tightly packed together, the convex side of one fitting into a concave depression In another (No. I Plate 5 ). Some of the ovoid or sub-ovoid forms which lack concentric structure may have been oolites in which dolomitization has reached a more advanced state and destroyed all evidence of concentric layering. The oolitic limestones of the Herald Member conformably overlie the dolomitic, mottled limestones of the Yeoman Member, but where the oolitic limestones pass laterally into evaporites and fossiliferous fragmental limestones, they usually overlie argillaceous dolomites. (Figures 4, 6 and 7 ). Over the rest of the map area, these dolomites lie between the lowest anhydrite bed and the Yeoman Member. Along the eastern edge of the map area the oolitic limestone interfingers with anhydrites. Where the oolitic limestones overlie the mottled limestones of the Yeoman Member, the contact between the two members is not obvious on the mechanical logs and was based on visual examination of cores and samples. A similar situation arises with regard to the upper contact between the oolitic limestones and the overlying fossiliferous fragmental limestones (Figure 2). Argillaceous Dolomites- The argillaceous dolomites of the Herald Member underlie most of the map area and extend beyond the limits of this region in all directions. They attain their greatest thickness within the report area, averaging about 20 feet in the International Border area and become thinner towards the north, west and east. Towards the southeast corner of the region of study and along the southern part of the extreme eastern edge to about township 21 (Figure 8 ), the argillaceous dolomites thin to zero against the oolitic limestones of the Herald Mem, ber. According to Porter and Fuller (1959 ) the argillaceous dolomites also have been observed in southern Manitoba. These rocks consist of a "chalky" argillaceous dolomite, buff in colour with an earthy, cryptocrystalline texture and grain size. Towards the north they appear more crystalline and less argillaceous. Poorly preserved fossil remains occasionally occur. The most easily identified of these 1 See footnote, p. 13. 15 z IMPERIAL HERALD No, I-31 Ll..d. 1-31-1-20 W2 <( ~ i. t w er } Id· t ::::> t _J Cf) j I STONEWALL z <( l) z 0 UN O ~ ::;; a:: 0 u. GUN TON MEMBER .., ARGtlLACEOUS DOLOMITES<') ~ f--'-------~1-> ~ YEOMAN MEMBER ,\ 'i CHARACT ERISTIC SECTION OF UPPER ORDOVICIAN STRATA OF THE INTERNATIONAL BOUNDARY AREA SASKATCHEWAN SHOWING PHASES OF EVAPORITE CYCLES (AFTER PORTER ANO FULLER, 19!59) LEGEf'fO .. ,...._,.,..,.._. Figure 3- Characterlstlc Section of Upper Ordovician Strata of the Int!l,rna• tlonal Boundary Area, Saskatchewan. GaD1JDa ray and Neutron cur ves from logs of the Imperial Herald No. 1-31 well (Lsd 1-31-1-20w2, Saskatche· wan) . Lithology from several cored sections In the International Boundary Area of southeastern Saskatchewan. 16 remains were scolecodonts, ostracods and crinoid stems taken from the cored interval 7050.2 feet to 7054.5 feet below kelly bushing, in the Tidewater Panamerican White Bear Crown No. 5-15 well (Lsd 5, Sec. 15, Twp. IO, Rge. 2, w2M ). Dark brown euhedral crystals of anhydrite are often disseminated through the rock, as radiating clusters or single crystals. The argillaceous dolomites are represented on radiation logs by an increase in gamma radiation counts and a corresponding increase in induced radiation counts as compared to the underlying and overlying strata (Figure 3 ), and the upper and lower boundaries were established by the author at the deflection points on the gamma ray well logs. The lower inflection on the neutron curve will also be found useful in establishing the base of the argillaceous dolomite, but the upper inflection cannot be used as an accurate means of limiting the upper boundary. These rocks are underlain by the mottled dolomitic limestones of the Yeoman Member .and overlain by the lowest evaporite deposits of the Herald Member (Figures 5 and 7 ). Evaporites- The Herald Member contains two evaporite horizons, termed the "A" and "B" Evaporites by the author. The "A" Evaporite is the lowest, stratigraphically, and underlies most of the map area (Figure 8 l. The unit for the most part is composed of the following lithologies in ascending order: 5 feet of evaporitic, argillaceous dolomite, 5 feet of anhydrite, 3 feet of evaporitic argillaceous dolomite, 12 feet of anhydrite. The maximum overall thickness of the unit ranges from 23 feet to 25 feet. Towards each limit of the "A" Evaporite (Figure 8 ) the two anhydrites merge into a single bed about 15 feet thick (Figure 7 ) ; this is usually overlain by a thin evaporitic, argillaceous dolomite bed. The second evaporitic layer or "B" Evaporite underlies an area along the International Boundary extending from range 2 to range 24 west of the second meridian, and from township IO southward across the Saskatchewan-North Dakota border. The "B" Evaporite includes an anhydrite bed about IO feet thick between two thin (about 5 feet ) eva, poritic, argillaceous dolomites. It attains a maximum thickness of 20 feet in the south-central portion of the map area and thins to a depositional thickness of about 5 feet towards its limits (Figure 4 and 5 ). These evaporitic units of the Herald Member are composed of massive or poorly bedded anhydrite and thin evaporitic dolomites. 1 The anhydrite is dark brown to gray (occasionally pink) in color with a cryptocrystalline to microcrystalline, sugary texture. The middle portion of the anhydrite beds is usually relatively free of dolomite and is composed of irregularly~ shaped grains with interlocking boundaries. The grain size ranges from 0.01 mm. to 0.05 mm. More elongated grains have also been observed; they are usually arranged in imperfectly radiating clusters or groups of subparallel grains. The subparallel orientation of the grains is not 1 Edie (1956) describes evaporitic dolomites as having the following characteristics: "1.- Dense (cryptocrystalline texture) 2.- Non-porous 3.- Sharp-bedding laminae ("varved") 4.- Interbedded with and intermixed with anhydrite 5.- Nonfossiliferous 6.- Non-cherty 7.- Salt-casts 8. - Argillaceous 9.-Quartz silt absent or negligible." 17 necessarily in the same direction from group to group (No. I Plate 2 ). Any dolomite that may be present in the middle portion of the anhy; drite beds is in the form of veins. In the vicinity of the dolomite veins the anhydrite is in the form of thin, elongated grains with lengths from 0.05 mm. to 0.3 mm. They are aligned parallel or subparallel to one another, with microfolds and crenulations occurring in the zone immed; iately surrounding the vein;like dolomite (No. 2 Plate 2 ) . The anhydritic layers are gradational with dolomites, and as the contact between the two lithologies is approached lenses and interbeds of dolomite and anhydrite are common occurrences. The anhydrite grains near the contacts take on an irregularly-shaped ha bit or are in the form of rounded grains less than 0.01 mm. in diameter. Layers and clusters of rounded, cryptocrystalline dolomite are present in the anhydrite (No. 1 and No. 2 Plate 3 ) a nd suggest lenses or stringers when observed in thin section. Aggregates of irregularly-shaped anhydrite grains enclosed in thin layers of argillaceous, cryptocrystalline dolomite have also been observed (No. 1 Plate 4 ). Thin elongated crystals of anhydrite are dis, persed through the dolomite s_urrounding the aggregates. Carbonaceous material is commonly present in thin beds in the anhydrite and is often intermixed with the lenses and interbeds of anhydrite and dolomite near the contact of the two rock types. The evaporitic dolomites which have been included in the evaporitic units are found at the upper boundary of the "A" Evaporite and the top and bottom boundary of the " B" Evaporite. These dolomites are usually thinly bedded (varve,like ), lithographic and slightly argillaceous. Occasionally interstitial anhydrite grains are present. The dolomites do not usually exceed 5 feet in thickness, but near the northern and western limits of the evaporitic accumulations, the anhydrites very often pass laterally into thicker beds of evaporitic dolomite. The top few inches of the uppermost dolomite in each evaporitic unit is frequently composed of a breccia of dolomite pebbles and sand grains with an argillaceous matrix. The "A" Evaporite is conformably overlain by a sparsely fossiliferous to coquina;like dolomitized limestone while the underlying rocks are argillaceous dolomites. The contact between the "A" Evaporite and overlying rocks is usually relatively sharp and is represented by a breccia or slump zone in the thin dolomite beds. Along the eastern edge of the map area the " A" Evaporite interfingers with the oolitic limestones (Figure 6 ) but in the western a nd northern portions of the area of study it passes laterally into thinly bedded, lithographic dolomites and these in turn into microcrystalline, dense dolomites. The "B" Evaporite divides the fossiliferous fragmental limestone into upper and lower units. On the northern and eastern limits this evaporite passes laterally into the fossiliferous fragmental limestones, but towards the west it thins out against the top of the Herald Member. Fossiliferous Fragmental Limestones- The fossiliferous fragmental limestones lie between the evaporitic units and between the "B" £vapor; ite and. the top of the Herald Member, and are widespread over the area of study. In the south central portion of the map area these rocks are subdivided into an upper and lower unit by the "B" Evaporite (Figure 3 ). The areal extent of both the upper and lower division is similar to the area underlain by the " B" Evaporite (Figure 8 ). The lower fossiliferous fragmental limestone attains a maximum thickness of 40 feet in the Imperial Halkett No. 15;7 well (Lsd 15, Sec. 7, Twp. 3, Rge. 8, w2M), but thins to about 20 feet towards the north, east and west from this well. The upper fossiliferous fragmental limestone is more consistent and 18 has an average thickness of about 15 feet. Beyond the limits of the "B" Evaporite (Figure 8 ) the fossiliferous fragmental limestone is a single unit. It has a wide and varying range of thickness, being about 25 feet thick along the western edge, and thinning to about IO feet in the northwest corner of the area studied. Along the eastern side of the map area outside the area underlain by the "B" Evaporite, the fossiliferous fragmental limestones (Figure 6 ) form a single unit ranging in thickness from IO feet in the north to 30 feet in the southeast corner of the map area. The fossiliferous fragmental limestones are buff to tan in color with a microcrystalline texture. Dolomitization is evident in these rocks and increases in intensity from the center of the basin (Figure 9 ) towards the peripheries. Beyond the limits of the "A" Evaporite (Figure 8 ) the fossiliferous fragmental limestones pass laterally into dense microcrystalline dolomites. In the southeast portion of the area of study the fossil fragments are often so tightly packed as to form a coquina with little matrix present. For the most part the rocks of the unit consist of fossil remains in a partially or highly dolomitized, microcrystalline, sucrosic matrix. The fossils present include brachiopods, cephalopods, bryozoa, corals and crinoid ossicles and plates. A considerable amount of anhydrite is dispersed throughout the rock, particularly in those portions of the fossiliferous fragmental limestones which underlie the evaporitic deposits. The anhydrite is present in four forms : I. Pseudomorphs of fossil fragments, particularly crinoid ossicles and brachiopod remains. 2. Radially arranged clusters or isolated subhedral to euhedral porphyrocrysts. 3. Blebs of massive anhydrite. 4. Veins of anhydrite. The porphyrocrysts and blebs of anhydrite are the most common forms of anhydrite in the fossiliferous fragmental limestones. The porphyrocrysts usually range in length from 0.2 mm. to 1 mm., occasionally longer. They are tabular, rectangular crystals, dark brown in color. The blebs, ranging from 7 mm. to 90 mm. in diameter, often appear to represent infilled vugs and passages in the rock. They consist of white, translucent cryptocrystalline to microcrystalline anhydrite. In thin section the grains are irregular with interlocking margins (No. 2 Plate 5 ) and are 0.001 mm. to 0.1 mm. in size. Veins or veinlets of dark brown, microcrystalline anhydrite have been observed cutting both previously crystallized anhydrite and the enclosing rock. Gypsum and chert also occur in small quantities in the fossiliferous fragmental limestones. The gypsum is usually in the form of selenite crystals, radially arranged satin-spar, or veins. It was also observed in the form of microcrystalline grains infilling the ta bulae of a favositid coral. The top of the Herald Member (the top of the Red River Formation ) is marked in two distinct ways in different parts of the area. In the southeastern portion of the area of study, where the shale facies of the Stony Mountain Formation is fully developed, the base of this shale facies marks the top of the Red River Formation. This contact has been observed in the Imperial Arm River Annandale No. 6-23 well (Lsd 6, Sec. 23, Twp. 8, Rge. 32, wlM) as a sharp Iithologic break. At the contact the Red River Formation consists of an extremely dense, lithographic dolomite with disseminated and veined pyrite; some pyrite crystals are also present in the small vugs in the rock. Conical shaped tubes extend down 19 into the dolomite from the bedding plane between the dolomite and over, lying shale. The tubes are infilled with calcareous material and appear to be worm or pelecypod borings. From its appearance, the contact between the two formations probably represents a short period of nondeposition. The shale facies of the Stony Mountain Formation thins rapidly in a northwesterly direction and the top of the Red River Formation is then marked by a thin bed of argillaceous dolomite which appears at the top of the fossiliferous fragmental limestone, and shows increase in gamma radiation on the radioactivity well logs (Figure 3 ). This marker becomes less conspicuous towards the western and northern edges of the map area until it is almost impossible to distinguish between the underlying and overlying rocks. STONY MOUNTAIN FORMATION The Stony Mountain Formation overlies the Red River Formation and appears to be conformable with it but for a break in sedimentation, which seems to have occurred especially in the eastern part of the studied area. This formation is widespread over the entire report area, but toward the northern and western edges of this region, it becomes less distinctive and more difficult to distinguish from the underlying and overlying strata. The Stony Mountain Formation has an average thickness of about 110 feet, varying but little over the whole area. It has been subdivided into two members, the Stoughton Member and the Gunton Member. Stoughton Member The Stoughton Member comprises the lower rocks of the Stony Mountain Formation. The name Stoughton Beds was -applied to these strata by the Lower Palaeozoic Names and Correla tion Committee of the Saskatchewan Geological Society (1958 ) (Table 1), while the term Stoughton Member was introduced by the present author for the same sequence of rocks. The Stoughton Member occurs only in the south, eastern part of the map area. It has a maximum thickness of 70 feet in the Socony Western Prairie Imperial Carievale No. 16-4 well (Lsd 16, Sec. 4, Twp. 3, Rge. 32, wlM ) and thins to zero feet in a westerly and northerly direction from that well. This member may be subdivided into two smaller units, a calcareous shale facies and a carbonate facies (Fig, ures 2 and 3 ). Shale f acies- The shale fades underlies the region southeast of an irregular line (hereinafter referred to for simplicity as the "shale line" ) running diagonally across the southeast corner of the map (Figure 8 ) from township 1, range 24, west of the second meridian to township 34, range 30, west of the first meridian. The shale fades also reaches its maximum thickness of about 70 feet in the Socony Western Prairie Im, perial Carievale No. 16-4 well (Lsd 16, Sec. 4, Twp. 3, Rge. 32, wlM ) but it thins more rapidly than the entire Stoughton Member and is about 15 feet thick at the "shale line" where it passes laterally into the car, bonate fades (Figures 4, 5 and 6 ). The.shale fades consists of interbedded dark grey, highly calcareous, fossiliferous shales and an extremely argillaceous, fossiliferous limestone. Both lithologies are so closely associated that one can only be differen, tiated from the other with extreme difficulty. Carbonate jacies- As the shale fades thins towards the north and west from the southeast corner of the map area an increasing thickness of limestones makes up that part of the member between the base of ths shale fades and the top of the Red River Formation. These carbonates 20 thicken from about 5 feet in the southeast (Figure 4 a nd 6 ) to about 35 feet on the north and west sides of the "shale line." However, beyond this line they become less limey and more dolomitic until they can not be distinguished from the overlying or underlying strata. The carbonate facies is made up of a dark brown, fossiliferous frag; mental, occasionally slightly argillaceous limestone. It has a crystallin.:> granular texture (medium to fine ) and is often so highly fossiliferous as to warrant the term coquina. The fossils present are mostly brachiopods and corals with some crinoid ossicles and bryozoa. Thin, gray, calcareous shale streaks are sometimes present. The brown coloration of this hori zon is distinctive and is easily distinguished in sample cuttings. The lower contact of the Stoughton Member is represented by different markers from east to west. In the southeast, where the shale facies attains its maximum thickness, the base of the shale facies and the contact of the Stoughton Member with the Red River Formation are coincident. This is represented by a sharp lithological break previously described. As the shale thins northward and westward the contact between the Stoughton Member and Red River Formation is represented by the top of an argillaceous dolomite horizon. The upper contact between the Stoughton Member and the overlying Gunton M ember is dependent on the top of the shale facies as far as the "shale line." On the north and western side of this line the top is placed at the top of an argillaceous dolomite marker which eventually thins over a very short distance, when the Stoughton and Gunton Members coalesce into one unit. Gunton Member The Gunton Member conformably overlies the Stoughton Member. In the northern and western parts of the map area where these units can no longer be distinguished from one another, they form one single unit: the Stony Mountain Formation. The Gunton Member thickens slightly from about 55 feet in the southeast corner to about 75 feet where it coalesces with the Stoughton Member (Figures 4, 5 and 6 ). The Gunton Member comprises mostly buff and tan mottled, nodular, slightly argillaceous, fossiliferous, dolomitic limestones. The buff areas are of a soft, sucrosic (microcrystalline ) and porous lithology, while the tan areas are hard, dense and cryptocrystalline to microcrystalline. Some thin dark grey, dolomitic shale beds are present as stringers in the rocks, along with black carbonaceous material which infills the internodular regions. Gunton Evaporite- The Gunto11 Evaporite occurs near the top of the Gun ton Member (Figure 3 ). It occupies an area almost coincident with that underlain by the "B" Evaporite of the Red River Formation (Figure 8), but it extends into Manitoba as an east-northeastward trending arm underlying the region between Townships 13 to 21 along the ManitobaSaskatchewan Interprovincial Boundary (Figure 8). The evaporitic unit has an average thickness of about 5 feet. At its limits it passes laterally into the dolomitic limestones which comprise the rest of the c ~mton Member. Dark brown, microcrystalline, sucrosic, dense anhydrite containing stringers and laminations of dark brown, lithographic, dense dolomite make up most of the evaporite sequence. A bed of evaporitic dolomite (see footnote p. 17 ) about 21 feet thick which underlies the anhydrite has also been included in the evaporitic sequence. The Gunton Evaporite is overlain by a bed of elastic material which marks the top of the Gunton Member and the Stony Mountain Forma; tion (Figures 2 and 3 ). This bed is marked by a distinct increase in gamma 21 radiation counts and can be traced over the entire report area. It is one of the most consistent marker horizons in the Lower Palaeozoic strata and can be traced into the outcrops in Manitoba. This marker horizon thickens from about 5 feet in the west and north to 10 feet in the southeast corner of the area of study. (Figures 4, 5 and 6 ). In the north and west of the report area the marker is composed of argillaceous dolomites. These pass south and east into grey, hard and blocky, dolomitic shales and these in turn into brownish-red, silty, dolomitic shales still further east. STONEWALL FORMATION The Stonewall Formation is conformable with the underlying strata. It represents the end of Ordovician sedimentation in the area and the uppermost part of this unit may even be Silurian in age. This unit may also be traced over most of the area of study but on the western and northern edges of the map area the lithology becomes increasingly like that of the overlying Interlake strata and finally becomes indistinguish, able from it. The Stonewall Formation maintains a fairly uniform thick, ness of about 100 feet over most of the area studied; however, in the northwest portion it thins to about 60 feet and in the west to a bout 75 feet. It is composed principally of carbonate rocks with a relatively thin evaporite horizon near the base. The carbonate rocks consist of tan and brown mottled, sometimes nodular and argillaceous, dolomitic limestone. Some poorly preserved fossils have been observed in these rocks, including brachiopods, bryozoa and crinoid ossicles and plates. A few ostracods were also seen in what appear to be lenses of argillaceous dolomite in the dolomitic limestone. Blebs of white translucent anhydrite and brown, tabular porphyrocrysts of anhydrite similar to those reported from the fossiliferous fragmental limestones of the Red River Formation are present, particularly in the rocks underlying the evaporite sequence. Stonewall Evaporite- The limits of this evaporite unit are almost identical to those of the underlying Gun ton and "B" Evaporites (Figure 8 ). The Stonewall Evaporite underlies a region along the International Boundary which extends from range 23 west of the second meridian eastward into southwestern Manitoba, and from township 10 southward into North Dakota. It has an overall average thickness of about 12 feet but thins slightly in an easterly direction into Manitoba. The evaporite consists of about 5 feet of dark brown, microcrystalline, sucrosic, dense anhydrite with stringers of dolomite bounded by two beds of lithographic, thinly bedded, slightly argillaceous dolomite, each about 3 feet thick. The presence of a second evaporite near the top of the Stonewall Formation has been suggested by Porter and Fuller (1959 ) but the author has found little evidence of this. There is a prominent marker horizon near the middle of the Stonewall Formation which was called the "t" horizon by Porter and Fuller (1959 ). It is easily traced over most of the report area and is characterized by an increased gamma radiation count on the radiation logs. The marker bed is about 7 feet thick and consists of argillaceous dolomite with "floating," frosted and well-rounded quartz grains. Eastward this horizon becomes a gray sandy dolomite which grades into brownish-red sandy shales. A second but less prominent marker bed marks the top of the Stonewall Formation. This marker is not as extensive as Porter and Fuller's ( 1959 ) " t" horizon and is not easily observed beyond the western and northern limits of the area of study. It is made up of about 5 to 15 feet of argillaceous dolomite with occasionally well-rounded and frosted, "floating" quartz grains. 22 Plate 1 Photomlcrographs (all transmitted light and crossed nlcol11 ) No. 1 Red Ri ver Formation X 45. Oolitic limestone showing matrix replaced by microcrystalline anhydrite. Some corroded pieces of matrix are isolated in the anhydrite. Dolomitization has destroyed much of the structure of the oolites. The California Standard-Tidewater Camoustie Province No. 4-20 well (Lsd 4-20-17-32wl ) Saskatchewan; 4615 foot depth. No. 2 Red River Formation X 15. Oolomitized oolitic limestone Matrix dolomite. Anhydrite in the form of elongated crystals cutting oolites. Concentric layering in oolites poorly preserved due to dolomitization. The Canadian Devonian, Tidewater Rupe.rt No. 15,28 well (Lsd 15,28-12,2w2) Saskatchewan; 6302 foot depth. 23 PETROLOGY OF THE ANHYDRITES AND EVAPORITIC DOLOMITES THE ORIGIN OF THE ANHYDRITES Anhydrites that are the result of replacement of carbonate rocks are of little value for correlation or subdivision purposes, though they may affect the porosity and permeability of a potential or actua l oil reservoir. The anhydrites that are end-products of dessication in a restricted basin are more useful. This latter type of anhydrite deposit has certain identifying characteristics that assist in distinguishing it as primary rather than a secondary deposit. In the case of the "A" and " B" Evaporites of the Herald Member and of the Gunton and Stonewall Eva porites, the criteria for the primary rather than secondary origin of these deposits may be divided into macroscopic and microscopic classes. The macroscopic features include: (1) The areal extents of the anhydrites, which were discussed under the section concerned with the stratigraphy. (2) The relatively uniform thickness of the anhydrites over wide, spread areas, also considered under the stratigraphy of these rocks. (3 ) The cyclic nature of the anhydrites as they are repeated throughout Upper Ordovician times. Hollingworth (1947 ) observed similar physical characteristics in other evaporite deposits, and he concluded that any anhyd rite containing the above features was laid down in an evaporite basin. (4) Thin carbonaceous layers were observed in the anhydrites and associated dolomites, and it has been suggested that these layers represent decayed organic material that was washed into the evaporating basin, and therefore indicate that the anhydrites were primary deposits and not secondary. (5 ) Numerous microfaults, microfolds and thin intraformational breccia are present in the anhydrites and associated dolomites. These structures appear to be the result of preconsolidation slumping in the precipitated material lying on the bottom of the evaporite basin. Fowler (1944 ) a nd Hollingworth (1947 ) observed similar microstructures in anhydrite deposits and attributed them to this cause. On the other hand Ogniben (1957 ) and Groves (1958 ) favour the theory that these structures were due to the expansion of the anhydrite with the addition of water to form gypsum. The fact that anhydrite is now present in the sequence would require a dehydration of the gypsum at a later stage of diagenesis. The load pressure caused by the overlying sediments and increased temperature with depth of burial may have caused the dehydration of the gypsum. Ogniben (1957 ) calls this second-cycle anhydrite "epigenic anhydrite." If the diagenetic process favoured by Ogniben and Groves did take place in the ·rocks of this report area, relic gypsum crystals would be expected to be present, but the author did not observe any in thin sections. However, some or indeed all of the secondary anhydrite may be second cycle or "epigenic anhydrite" as some of them show blastomylonitic zones (No. 2 Plate 4) around the peripheries. These zones are thought by Ogniben (1957 ) to represent the fragments left after the expansion and rupture of anhydrite crystals. Several microscopic features may indicate the primary nature of the 24 Plate 2 - Photomicrographs ( all transmitted light and crossed nicols) No. l "A" Evaporite. X 45. Anhydrite composed of elongated, roughly rectangular grains with irregular margins. Grains orientated more or less parallel in groups but orientation varying from group to group. The Imperial Hummingbird No. 6-13 well (Lsd 6-13-2-19w2) Saskatchewan; 9846 foot depth. No. 2 "A" Evaporite. X 45. E longated, microcrystalline grains of anhydrite with parallel alignment (gneissoid texture) . Microfolds due to foreign carbonate bodies. The Imperial Muscowpetung No. 1-9 well (Lsd 1-9-21-16w2) Saskatchewan; 5806 foot depth. 25 anhydrites of the Upper Ordovician in the report area. These features include: (1) The crystals of the anhydrite are commonly orientated in patches, but the orientation of one patch is not necessarily the same as that of another (No. 1 Plate 2 ). Unless this orientation is inherited from a previously existing rock, it seems probable that the anhydrite was the result of direct precipitation. Dunham (1948 l considers these patches of oriented grains to have been caused by a disturbance of the accumulated crystals by eddies and currents during deposition. He says that rocks of this type which lack fully developed idiomorphic crystals, either as phenocrysts or constituents of a groundmass, suggest that the anhydrite began to crystallize in suspension in the brine, and that crystallization completed on the evaporitic basin fl oor, resulting in mutually interfering crystal boundaries. Some recrystallization of the anhydrite may have occurred after deposition producing the gneissoid texture (Bundy, 1956 ) observed in some specimens (No. 2 Plate 2 ). (2 ) The occurrence in these rocks of anhydrite blebs enclosed by a thin layer of cryptocrystalline dolomite, as illustrated in No. 1, Plate 4, is further proof of the primary nature of the anhydrite. Each Ienticle is piled on the others, and separated from them by a thin layer of marl. The lenticles probably represent gell-Iike balls of anhydrite which were formed on the floor of the evaporating basin and which were later enclosed in dolomitic marl. This hypothesis is in accordance with a similar one proposed by Dunham (1948) for anhydrite showing the same characteristics in the Permian-evaporites of northeastern England. The anhydrites appear to be primary, having been laid down in an evaporitic basin and later covered over by younger sediment. Since most of the diagnostic features can be attributed to first-cycle anhydrites 1, they can be considered to have gone through very little alteration or recrystallization. SECONDARY ANHYDRITE The secondary anhydrite is found in the dolomitic limestones in the form of porphyrocrysts, large blebs, and pseudomorphs of fossil remains. The mechanisms which produced these secondary deposits are not entirely clear. The porphycrocrysts and pseudomorphs of fossil remains may be attributed to seepage of the concentrated brine through the underlying poorly consolidated muds with the subsequent replacement of the carbonate material by the sulphate material. But in the case of the blebs of anhydrite this theory does not account for the facts, since in thin section the anhydrite of the blebs has a crystal habit similar to the primary anhydrites,- that is, idiomorphic crystals with interlocking boundaries (No. 2 Plate 5 )-and it would appear that this anhydrite was deposited after consolidation and infilled vugs in the rock. Adding weight to this idea is an observation made by Fowler (1944 ) concerning parallel conditions in some anhydritic sequences in the Cleveland Hills area in England. Stylolitic sutures are common in these carbonate rocks of Fowler's area and he suggested that, if the anhydrite blebs were preconsolidation features they too should have stylolitic structures, since the anhydrite is more soluble than the carbonate. He also found bluishwhite granular anhydrite intruded along the sutures. Stylolites are also 1 Anhydrite as it was laid down in the evaporite basin, as opposed to anhydrite obtained from the dehydration of gypsum at depth. 26 Plate 3 - Photomicrographs (all transJ:Ditted light and crossed nicols) No. 1 Red River Formation. X 45. Rounded anhydrite grains with interstitial rounded dolomite grains in clusters or thin layers. The California Standard- Tidewater Carnoustie Province No. 4,20 well (Lsd 4,20,17,32wl ) Saskatchewan; 4606.8 foot depth. No. 2 Red River Formation. X 45. Rounded anhydrite grains with interstitial dolomite grains in clusters or thin layers. The Imperial Arm River Annandale No. 6,23 well (Lsd 6,23,8,32wl ) Saskatchewan; 6334.0 foot depth. 27 common in the Upper Ordovician rocks of the area of study and large quantities of bluish;white granular an hyd rite was observed infilling low areas along the stylolite sutures. From this evidence, it appears that the anhydrite blebs are post;consolidation fe:1tures. The wri ter feels that the anhydrite could have been brought to these vugs in one of t wo ways: (1 ) by circulating sulfate;rich ground waters. (2 ) by the waters resulting from the dehydration of gypsum. Since most of the anhydrite blebs underlie an impervious layer of evapo; rites, it seems unlikely that sul fate;bearing ground waters could circulate through the rock sequence to any great extent, and only a portion of the blebs can be attributed to this mechanism. If the anhydrites of the " A" and "B" Evaporites, and of the Gunton and Stonewall Evaporites were considered to be epigenic, then the sulfate;bearing waters could be attributed to the diagenetic processes that took place to form the "epi; genie anhydrite" in that, following the deposition of the anhydrites in the evaporitic basins, they would have been hydrated to gypsum with the return to normal marine conditions. As more and more sediments were laid down, the pressure on the gypsum and the temperature of the buried sediments would increase and finally, when the temperature and pressures were too extreme for gypsum to exist any longer, the water of hydration would be driven off and anhydrite formed again. The water of hydration would probably still contain a certain amount of calcium sulfate, and as it came in contact with the underlying carbonate rocks, would deposit it in the porous zones and vugs. If this hypothesis is correct, then the microscopic features of the primary anhydrites which were described in the previous section are not the result of the deposition of the anhydrite, but were produced by the recrystallization of the anhydrite from gypsum. EVAPORITIC DOLOMITES The possibility or otherwise of the primary deposition of dolomite has been a controversial issue for many years. Bury (1947 ) says that primary dolomite cannot be formed because the carbonates of calcium and magnesium are formed under such different chemical conditions. Twenhofel is also of the opinion that the primary deposition of dolomite is purely hypothetical, but Sanders, as quoted by Edie (1956), found thinly laminated dolomites with penecontemporaneous slumping which he felt demonstrated the feasibility of the theory that dolomite muds may be deposited under proper conditions. A recent paper by Alderman and Skinner (1957 ) describes dolomite sedimentation in the southeast of South Australia. They observed that a close relationship existed between plant growth, rise in pH value, and the precipitation of dolomitic sediments in evaporating basins. Laboratory experiments were carried out by Graf and Goldsmith (1956) in an attempt to precipitate dolomite from solutions under a wide range of temperatures and pressures. They found that the stable form of dolomite, 1:1 Ca :Mg, could only be obtained under extreme conditions of temperature and pressure, but an unstable form, which they called protodolomite (dolomite;like rocks ), may be deposited at temperatures and pressures app roaching standard conditions. These protodolomites may later pass into a more stable phase. This may be a mechanism by which primary dolomites are formed. The rocks of Upper Ordovician age in the report area that are thought to be evaporitic dolomites are: (1) Thinly laminated (2 ) Dense (cryptocrystalline texture ) 28 Plate 4- Photomicrographs {all transmitted light and crossed nicolsJ No. 1 Red River Formation. X 45. Aggregates of cryptocrystalline, irregular, anhydrite crystals enclosed by thin layers of lithographic dolomite containing acicular crystals of anhydrite. The [mperial Hummingbird No. 6, 13 well (Lsd 6, 13,2,19 w2) Saskatchewan; 9848.5 foot depth. No. 2 Red River Formation. X 45. Microcrystalline, dolomitic limestone (D ) with large (2cm.) chert nodules (C). Subhedral crystals of anhydrite (A) as meta, somatic replacement of dolomite. The Canadian Devonian,Tidewater Rupert No. 15, 28 well (Lsd 15,28, 12,2w2) Saskatchewan; 6297 foot depth. 29 Plate 5- Photomicrographs (all transmitted light and crossed nicols) No. I Red River Formation. X 45. Dolomitized limestone with deformed pseudo, oolites and subhedra l secondary anhydrite crystals. The Imperial Hartaven No. 2,11 well (Lsd 2-l l , 10,9w2) Saskatchewan; 7499.0 foot depth. No. 2 Red River Formation. X 45. Dolomitized fossiliferous fragmental limestone with anhydrite infilling vugs. Zone closest to the anhydrite (A) has well preserved fossil remains, but these are more indistinct farther away due to more intense dolomitization. The Imperial Arm River Annandale No. 6,23 well (Lsd 6, 23, 8,32wl ) Saskatchewan ; 6356.5 foot depth. 30 (3 ) Argillaceous (4 ) Interbedded and intermixed with anhydrite (5 ) Non-fossiliferous. These features are similar to those described by Edie (1956 ) and Illing ( 1959 ) as characteristic of primary or evaporitic dolomites. The close association of dolomite and anhydrite as illustrated by Nos. 1 and 2, Plate 3 further adds to the evidence that evaporitic dolomites are present in Upper Ordovician rocks. Dunham ( 1948 ) said that rounded dolomite granules enclosed by anhydrite suggest minute foreign particles which acted as nuclei for the deposition of dolomite, the composition of the brine changing before crystallization could go further resulting in th e inclusion of dolomite in anhydrite. In conclus;on, it seems evident from the foregoing observations that primary or evaporitic dolomites are not an impossibility, and that such are indeed present in rocks of Upper Ordovician age of this area. 31 STRUCTURE The structure contours on top of the Yeoman Member illustra te the northern part of a basinal feature with radial dip s teepening towards the center of the basin (Figure 8 ). The arcuate sweep of the contour lines is interrupted in the southwestern part of the map area where the contour lines swing to a north-south direction on the flanks of the Bow, doin Dome (Porter and Fuller, 1959 ) (Figure 8 ). The distribution of deep wells that penetrated the Red River Formation within the limits of the area of study makes it possible to illustrate only the regional structural features. However, due to the closeness of two wells about 22 miles southeast of Moose Jaw and with the a id of seismic information, a small structural high was outlined. This structure is probably the result of an erosional high on the Precambrian uncon, formity reflected in the overlying rocks, including those of the Cretaceous System. The southern side of this anomaly forms a southward pitching anticline which eventually grades into the regional dip. Geophysical methods were also useful in locating a second structural high about 12 miles south of Swift Current (Figure 8 ). This feature, along with another high just outside the map area about 24 miles northwest of Swift Current, is also thought to reflect erosional highs on the Precambrian unconformity and they, too, affected the overlying sediments. These highs grade into an east-southeastward trending, pitching anticline, which occupies the site of Kamen-Kaye's (1953 ) Mesozoic Swift Current Anticline, but soon disappears downdip in the regional contours. On the northeast flank of the structural basin, a third local anomaly has been outlined in the vicinity of townships 7 to 10, ranges 32 and 33. It consists of a poorly developed anticline with a southwesterly pitch which as in the case of the previously mentioned features is eventually lost downdip. Because of the sparse well control, some known structural anomalies have not been illustrated in Figure 8. Most noteworthy among these is the structural high in the Elbow area, a very prominent feature on the seismic maps. In the south-central portion of the map area, in the vicinity of range 19 west of 2nd meridian, there is thought to be a tectonic hinge line trending north-northwest from the International Boundary. However, this hinge cannot be observed on the structure contour map, and can only be inferred from geophysical data. 32 I . I I " " .: . N If U II U U ff - ti 10 1• • 0, .. .. - M q, C ,a • - p '-· ,< ),,. .. - ... I . I./ .. . - ct. ,- I/' ,< > '(.. ~ / / I v I/ v r / ..f . ' / / I I .'\ ' \ I\ \ \ \ \ "\ I\ .;,,":':-..- -~ .J-.;-t J 1or --,- -,- ~ _ _ _ ---~ I 4 ) I STRUCTURE CONTOUR MAP LEGEND ON THE TOP OF THE YEOMAN MEMBER ' coNTOUR INTERVAL 200' Flrure 8- St ructure Contour Map on Top of the Yeoman Member 33 HUDSON BAY I l , \... \ ., .\ i HELENJI i( r. \ ·, / gJ .. ~ Metastable posit ive areas. B Stobie positive areas D Ne9at ive areas ~ Region of most extensive evoporite deposi tion WYOMING SCAL E I N MILES Figure &-Tectonic niap of the Prairie Provinces and Northwestern United States illustrating the positive and negative elenients (After Borden, 1958) and the D1anID\UJl area covered b:y the evaporite depollits during Ordovician tlnies. 34 SEDIMENTATION DEPOSITIONAL ENVIRONMENT The Upper Ordovician rocks of southern Saskatchewan were laid down in an intracratonic basin, the axis of maximum sedimentation of which occupied two separate positions during that time. During the period of Red River and Stoughton sedimentation the axis was present in the region northeast of Bismarck, North Dakota (Figure 9 ). The center of maximum sedimentation during the period of Gunton and Stonewall sedimentation shifted to a position about 100 miles northwest of its previous position. Repeated minor epierogenic movements in the basin resulted in periodic restriction of circulation and cyclic deposition, including eva, porites in the vicinity of the center of sedimentation. Since the evaporites are surrounded by sediments which were laid down in a marine environ, ment, Krumbein (1951 ) felt that the restriction of circulation in this basin was due to tectonically imposed barriers. In the case of the " A" Evaporite of the Herald Member, the presence of stratigraphically equivalent oolitic and pelletoidal limestones in the Herald Member along the Manitoba,Saskatchewan border indicates a shoal (Figure 9) which may have acted as a tectonic barrier in the region. But on the northwest side of the "A" Evaporite the evidence for a barrier is lacking, and the author feels that another mechanism may account for the restriction of the basin in this region. This mechanism, a dynamic barrier (Scruton, 1953 ) is mentioned in Figure 10. Scruton described a dynamic barrier as a strong friction surface created between fresh water, or water of normal salinity, and highly saline solutions. According to him the friction is great enough to inhibit the intrusion of the less dense water by the more dense. Barriers of this nature have been observed in the Gulf of Mexico off the distributaries of the Mississippi River, and Scruton felt that barriers of a similar nature may be essential to the entrapment of the brine in many evaporitic basins. To explain the presence of a dynamic barrier in the case of the "A" Evaporite, the lithology on the landward side of the evaporitic environment (Figure 10 ) must be considered first. The rocks of this area are similar to those described as "pseudomarine" by Sloss (1953 p. 160 ). Where rocks of this type are laid down Sloss considered the brine to have been diluted, probably by fresh water from the hinterland. The author feels that this theory is applicable to the region between the hinterland and the evaporitic environment (Figure IO ) and 'because of this dilution a dynamic barrier was formed which re, stricted the highly saline solutions to the area now occupied by the "A" Evaporite. The conditions of deposition for the " B" Evaporite of the Herald Member may have been similar to those under which the " A" Evaporite was laid down, but there is no lithological evidence of a barrier bank type environment being present in southern Saskatchewan. How, ever, this environment might have existed farther south in North Dakota or east in Manitoba and lithological evidence for its existence may be found in either place. Unlike the evaporites of the Herald Member, the Gun ton and Stone, wall Evaporites straddle the axis of maximum sedimentation (Figure 11 ); therefore the depositional environments for these later evaporite deposits are different from those of the earlier evaporites. These evaporites were probably laid down in shallow evaporating basins and represent the standstill period at the end of an epeirogenic uplift of the depositional basjn. The evaporating basin was probably surrounded by a calcareous mud,flat at about sea level. This flat was probably flooded periodically 35 SE NW. POSITIVE - PSEUOO·MARINE ENVlRO,otENT - --+-- - - - - - - - (VAPORITIC ENVIRONMENT - - - - - - --+-- - BARRIER AREA BANK - --+-- - 8.ANK MARGIN - ENVIRONMENT ENVIRONMENT Ool1t 1c ond Ptlltl L1mutone1 Foss,hferous Fro9ffltntol Oohtes ond Pellet::. Limestone C11no,d On1clu, Co,o l and 8'od11opod Fro;rMnts SEA LEVEL OYNAMIC BARRIER REGION .,,,,/!) c,,stolhnt Dolomite w,th poorlJ p,esuved Fosslts EwopMlttS ond •ctto111f Ar91ttoceovs Oolom,1ts w11h some Ost,ocods Figure 10- Generallzed section through the region of study illustrating the sedimentary environment present during the time when the "A" Evaporite of the Herald Member was deposited. causing an influx of normal sea water into the restricted basin; the addi; tion of normal sea water probably kept the salinity of the restricted basin at the proper concentration for the precipitation of anhydrite at all times. Since the Gunton and Stonewall Evaporites are extremely thin, this physical characteristic may be interpreted as an indicator of the shallow; ness of the basin and the relatively short period of time of deposition. The presence of silty, dolomitic shales and argillaceous dolomites im~ mediately overlying the anhydrites probably represents the end of the "stand;still" and the initiation of the return of the deposition basin to normal marine conditions. HUDSON BAY Unstable poslli\le areas WYOMING Metostob1e positive areas ,oo ,oo zoo Stable posit1ve areas SCALE IN MILES Negative oreos Figure 11-Tectonlc Map of Prairie Provinces and Northwestern United States illustrating the positive and negative elements (After Borden, 1966) and the distribution of the evaporltic basins during GuntonStonewall times. 37 EVAPORITIC CYCLES Each evaporite deposit in the Upper Ordovician strata of southern Saskatchewan is part of a cycle of sedimentation consisting of five phases (Figure 3 and Table 2 ). TABLE 2 Phase Lithology Cyclic Stages Limestone (D olomitized, sometimes fossilif, erous) Hemicycle of subsidence Phase Number 2 Argillaceous Dolomite or Dolomitic shale 3 Anhydrite 2 Argillaceous Dolomite period of standstill Limestone (Dolomitized, sometimes fossili, ferous) Hemicycle of uplift The lithology of phase 1 of the hemicycle of uplift is that which would be expected to have been deposited under normal marine conditions. The normal marine sedimentation was gradually brought to a close as the basin shallowed due to epeirogenic uplift; Phase 2 represents the transition phase from a normal marine environment to one of evaporation. The uplifted basin then entered a period of tectonic standstill and evaporites, such as those of Phase 3, were laid down in the restricted portions of the basin. In the hemicycle of subsidence the rocks of Phase 2 represent a second transition phase from dessicating conditions to a normal marine environment. Finally, Phase 1 of the upper hemicycle indicates a return to normal marine sedimentation. There were two cycles of uplift and subsidence during the period when the rocks of the Red River Formation were deposited. These cycles of sedimentation were interrupted by an upwarp (Ballard, 1942, p. 1577 ) southeast of the axis of maximum sedimentation (Figure 9 ). The move, ment was in the vicinity of the Sioux uplift according to Ballard, which occupied part of the area covered by the Transcontinental Arch of Devonian times (Eardley, 1951 ). The uplift resulted in an influx of fine elastic material into the basin from the southeast (shale facies of the Stoughton Member- Figures 2 and 3 ). There was also a shift of the center and axis of maximum sedimentation about 100 miles northwest, ward from their previous locations (Porter and Fuller, 1959 ) with the axis receiving a more northeasterly trend (Figure 11 ). Followir•g this shifting of the basin center two more cycles I of uplift and subsidence were initiated producing the deposits of the Gunton Member of the Stony Mountain Formation and the Stonewall Formation. A third shift of the center and axis of sedimentation to a position slightly farther west (Porter and Fuller! 1959 ) brought to a close sedimentation in Upper Ordovician times. 1 Porter and Fuller (1959) reported evidence of a third evaporitic cycle extending to the top of the Stonewall Formation but the present writer has found little evidence to verify this fact at this time. 38 PETROLEUM PROSPECTS The prospects for the production of oil and gas from the Lower Palaeozoic horizons have been discussed at considerable length by Porter and Fuller (1959 ) and the present author is of the opinion that little more can be added. They suggested (and the writer agrees ) that the best petroleum possibilities for the Upper Ordovician strata lie in the central basin area and on the low inner flank positions where the salinity of the formation water is high and the porosity of the facies is favourable to oil accumulation. Some oil has been produced from the Ordovician rocks in the central basin area and the low inner flank positions of the Williston Basin in Montana and North Dakota, but so far only three oil shows have been reported in Saskatchewan. The most significant oil show was observed in the Imperial Hummingbird No. 6-13 well (Lsd 6, Sec. 13, Twp. 2, Rge. 19, w2M ) which produced oil for a time from a horizon at the top of the Yeoman Member of the Red River Formation (Figure 4 ). The reservoir was thought to be a stratigraphic trap capped by dense evaporitic deposits with minor structural closure. The second oil show was observed in the drill stem tests of the interval 8264 feet,8309 feet (below kelly bushing ) in the Imperial Pangman No. 3-14 well (Lsd 3, Sec. 14, Twp. 8, Rge. 20, w2M ). This showing was from the same horizon (Figure 5 ) as that of the Imperial Hummingbird No. 6-13 well; both these wells appear to be on the same trend, which is thought to be a tectonic hinge area. The third oil show was Jess significant and was ob, served in the Imperial Herald No. 1-31 well (Lsd 1, Sec. 31, Twp. 1, Rge. 20, w2M ). One hundred and ten feet of gassy, muddy oil fluid and salt water were reported from a drill stem test of the Stonewall Formation between the interval 9321 feet to 9341 feet below the kelly bushing (elevation 2276 feet above sea level ) (Figure 4 ). Since the structure contour map on the top of the Yeoman Member shows few structures favourable to the entrapment of oil or gas, it would seem that any hydrocarbons present in the Upper Ordovician rocks of southern Saskatchewan have most likely accumulated in stratigraphic traps. These traps may be of two types: (a ) where an impervious rock such as anhydrite or shale forms the cap rock over the reservoir rock and the porosity pinches out up-dip as a result of a lateral change in facies, or (b ) where the possible reservoir rocks are bounded at the top and bottom by anhydrites or other impervious material. The porous fossiliferous limestones of the Yeoman Member, which underlie the "A" Evaporite of the Herald Member, and similar rocks which underlie the Gunton and Stonewall Evaporites and which are confined by the "A" and "B" Evaporites of the Herald Member, all pass laterally into dense dolomitic limestones up-dip and p1oduce reservoir conditions as defined previously. Recent deep drilling across the International Boundary in North Dakota has added impetus to a relatively new theory concerning the discovery of oil in the Lower Palaeozoic rocks of the Williston Basin area. This theory pertains to the indirect relationship between the accumula, tion of oil in the Lower Palaeozoic horizons, and the absence of or the thinness of the Middle Devonian Prairie Evaporites. It is thought that these "no salt" areas, as they are called, represent tectonic hinge areas which effected the reservoir conditions in the underlying strata. One such hinge region may exist in southern Saskatchewan trending north, ward from the area where the Imperial Hummingbird No. 6, 13 well was drilled. There are other small areas of "no salt" in southern Saskatchewan which may be tectonic hinge areas, and which may justify further in, vestigation, if the facies in the Lower Palaeozoic rocks is the type in which good reservoirs can be expected. Other evidence presented by 39 Kupsch (1958 ) and Meek ( 1958 ) also illustrates the possible existence of a tectonic hinge along the edge of the extensive "no salt" region in southern Saskatchewan which may also warrant further investigation for favourable oil entrapment conditions in the rocks underlying the Middle Devonian Prairie Evaporites. 40 BIBLIOGRAPHY Alderman, A. R. and Skinner, H. C. W., 1957, "Dolomite Sedimentation in SouthEast of South Australia,"-Amer. }our. Sci., Vol. 255, No. 8, pp. 561-567. Baillie, A. D., 1951, "Ordovician Geology of the Lake Winnipeg and Adjacent Areas Manitoba," Manitoba Mines Branch, Pub. 51-6. Ballard, N., 1942, "Regional Geology of Dakota Basin," Bull. Amer. Assoc. Petrol. Geo/., Vol. 26, No. 10, pp. 1557- 1584. Borden, R . L., 1956, "Historical Geology and Tectonics of the Southern Part of the Prairie Provinces, Canada," ]our. Alta. Soc. Petrol. Geo!. , Vol. 4, No. 6, pp. 134-140. Branson, E. B ., 1915, "Origin of thick salt and gypsum deposits," Bull. Geo/. Soc. Amer., Vol. 26, pp. 231-242. Briggs, L. I ., 1958, "Evaporite facies, " }our. Sed. Pet. , Vol. 28, No. 1, pp. 46-57. Bundy, W. M. , 1956, "Petrology of Gypsum-Anhydrite Deposits in Southwestern Indiana," }our. Sed. Pet., Vol. 26, No. 3, pp. 240-252. Bury, C. R., 1948, "Chemistry of Saline Deposits," Proc. Yorks. Geo/. Soc., Vol. 27, Part 3, pp. 205-209. Cast er, K. E ., 1934, "The Stratigraphy and Paleontology of Northwestern Pennsylvania," Part I: Stratigraphy, Bull. Amer. Paleontology, Vol. 21, No. 71. Chave, K . E., 1954, "Aspects of Biochemistry of Magnesium. and Rocks," }our. Geol., Vol. 62, No. 6, pp. 587-599. 2. Calcareous Sediments Dowling, D . B., 1900, " Report on the Geology of the West Shore and Islands of Lake Winnipeg," Geo/. Survey, Canada, Ann . Rept., 1898, Pt. F. Dunham, K . C ., 1948, "A Contribution to the Petrology of the Permian Evaporite Deposits of Northeastern England," Proc. Yorks. Geo/. Soc., Vol. 27, pp. 217-227. Eardley, A. J ., 1951, "Structural Geology of North America," Harper Bros., New York. Edie, R. W., 1956, "Origin and Characteristics of Evaporitic Dolomite," ] our. Alta. Soc. Petrol. Geo/., Vol. 4, No. 1, pp. 16-23. - - - - - -, 1958, "Mississippian Sedimentation and Oilfields in Southern Saskatchewan," Jurassic and Carboniferous of Western Canada, Amer. Assoc. Petrol. Geo/. Symposium, Allan Memorial Vofume, pp. 331 -363. Foerst e, A. F., 1928, "The Cephalopods of Putnam Highlands" in "Contributions to the Geology of Foxe Land, Baffin Island," Contrib. Mus. Paleontology, Univ. M ichigan, Vol. 3, No. 3, Pt. 2, pp. 25-69. - -- - - -, 1929, "Ordovician and Silurian of American Arctic and Subarctic Regions," Denison Univ. Bull., }our. Sci. Lab., Vol. 24, Art. 1-5, pp. 27-78. Fowler, A., 1944, "A Deep Bore in the Cleveland Hills," Geo!. Mag., Vol. 81, No. 5, pp. 193-206, 254-265. Fuller, J . G . C. M., 1956, "Mississippian Rocks and Oilfields in Southeastern Saskatchewan," Saskatchewan Dept. Mineral Resources, Rept. 19. Graf, D . L. and Goldsmith, J. R. , 1956, "Some Hydrothermal Syntheses of Dolomite and Protodolomite," ]our. Geo/., Vol. 64, No. 2, pp. 173-186. Groves, A. W. , 1958, "Gypsum and Anhydrite," Her Majesty's Stationery Office, London, England, pp. 1,8. Hollingworth, S. E., 1948, "Evaporites," Proc. Yorks. Geo/. Soc. , Vol. 27, Pt. 3, pp. 192-198. llllng, L. V., 1959, "Upper Palaeozoic Carbonate Sediments in Western Canada," Oilweek, Vol. 10, No. 17, pp. 34-45. Kamen-Kaye, M., 1953, "The Tectonic Patterns of Southwestern Saskatchewan, Canada," Guidebook Billings Geo!. Soc., 4th Annual F ield Conference, pp. 118-122. King, R.H., 1947, "Sedimentation in Permian Castile Sea," Bull. Amer. Assoc. Petrol. Geo!., Vol. 31, pp. 470-477. Krumbien, W. C., 1951, "Occurrence and Lithologic Association of Evaporites in the United States," }our. Sed. Pet., Vol. 21, pp. 63-81. 41 Kupsch, W. O., 1958, "Subsurface Structures in Southern Saskatchewan," North Dakota Geol. Soc. Sask. Geol. Soc., 2nd International Williston Basin Symposium Volume, pp. 118,126. Macdonald, G. J. F., 1953, "Anhydrite-Gypsum Equilibrium Relations," Amer. ]our. Sci. , Vol. 251, No. 12, pp. 884-898. McCamis, J. G., 1958, " Anhydritization in the Mississippian Souris Valley Beds of the Broadview Area, Saskatchewan," Unpublished Master of Science Thesis, Univ. Saskatchewan . Meek, K. S., Jr., 1958, "Precambrian of the Canadian Williston Basin," North Dakota Geol. Soc. Sask. Geo/. Soc., 2nd International Williston Basin Symposium Volume, pp. 17,19. Morris, R. C. and Dickey, P. A., 1957, "Modem Evaporite Deposition in Peru,' • Bull. Amer. Assoc. Petrol. Geo/., Vol. 41, No. 11 , pp. 2467,2474. Napier, E., 1948, " The Lower Anhydrite Seams of the Tees Area,'' Proc. Yorks. Geo/. Soc., Vol. 27, Pt. 3, pp. 210,216. Okulltch, V. J., 1943, "The Stony Mountain Formation of Manitoba,'' Trans. Roy. Soc. Canada, 3d. Ser., Vol. 37, Sec. 4, pp. 59,73. Ogniben, L., 1957a, "Secondary Gypsum of the Sulphur Series, Sicily, and the So-called Integration,'' }our. Sed. Pet. , Vol. 27, No. 1, pp. 64,79. - - -- , 1957b, "Discussions-Relation of Gypsum and Anhydrite,'' ]our. Sed. Pet., Vol. 27, No. 4, pp. 469,470. Ower, J . R., 1953, " The Subsurface Stratigraphy of Southwestern Manitoba,'' Trans. Can. Inst. Min. and Metal/., Vol. 56, pp. 391,399; Can. Min. and Metal/. Bull., No. 500, pp. 735,743. Porter, J. W. and Fuller, J . G. C. M. , 1959, "Lo.wer Palaeozoic Rocks of the Northern Williston Basin and Adjacent Areas," Bull. Amer. Assoc. Petrol. Geo/., Vol. 43, No. I, pp. 124,189. Rader, M. T., Jr., 1952, " Ordovician and Silurian Carbonates of the Central Williston Basin,'' Guidebook Billings Geo/. Soc., 3rd Annual Field Conference, pp. 48-55. - - , 1953, " Ordovician, Silurian and Devonian Stratigraphy of a Portion of Northern Montana," Guidebook Billings Geo/. Soc., 4th Annual Field Conference, pp. 64-66. Ross, R. J., Jr., 1957, Ordovician Fossils from Wells in the Williston Basin Eastern Montana,'' United States Geological Survey Bulletin 1021,M. Saskatchewan Geological Society, 1958, "Report of the Lower Palaeozoic Names and Correlation Committee.'' Scruton, P. C., 1953, "Deposition of Evaporites," Bull. Amer. Assoc. Petrol. Geo/., Vol. 37, No. 11, pp. 2498,2512. Sloss, L. L., 1953, " Significance of Evaporites,'' ]our. Sed. Pet. , Vol. 23, No. 3, pp. 143-161. Stanton, M. S., 1953, "Ordovician, Silurian and Devonian Stratigraphy of Western Saskatchewan,'' Guidebook Billings Geo/. Soc., 4th Annual Field Conference, pp. 59,63. Stearn, C. W., 1953, "Ordovician,Silurian Boundary in Manitoba," Abstract, Bull. Geo/. Soc. Amer., Vol. 64, No. 12, Part 2, pp. 1477,1478. - - - - - -, 1956, "Stratigraphy and Palaeontology of the Interlake Group and Stonewall Formation of Southern Manitoba," Geol. Survey Canada, Memoir 281 pp. 8-10. Stewart, F . H., 1949, "The Petrology of the Evaporites of the Eskdale No. 2 Boring, East Yorkshire, Part I, The Lower Evaporite Bed,'' Min, Mag., Vol. 28, No. 206, pp. 621-675. Wflllams, H., Turner, F. J. and Gilbert, C. M., 1955, "Petrography,'' W. H. Freeman and Co. , San Francisco, Calif. 42 APPENDIX Well Data Formation and member tops determined from cores, samples and mechanical logs. 41 rKelly Busbin~ Elevation 1 Well Name Location 1,4,17-30wl... ... 1,16-20-30,wl... .. 16-32-15-31wl... 16-4-3,32wl 3-18-3,32wl.. ..... 16-7-6-32wl . 14-19-8,32wl... . 6-23,8,32wl... .... . Stony Mtn. Formation (feet below K .B. ) 1580 1647 1731 1690 1733 1949 2097 1981 3963 3576 4462 7191 7265 6703 6310 6097 4043 3658 4557 7278 7362 6808 6416 6204 4161 3773 4662 7401 7482 6914 6533 6321 4218 3827 4722 7524 7580 6991 6588 6387 1791 4381 4469 4581 4642 --- Red River Formation (feet below K.B. ) Herald Yeoman Member Member Riddle Tidewater St. Marthe No. 1-4.............. . Riddle Tidewater Marchwell No. 1- 16............... . Riddle Tidewater Rocanville No. 16-32 ............ . Socony Western Prairie Imperia l Carievale No. I Imperial S ilverton No. 3,18 ........... .. .. . ..... . Imperial Lightning Creek No. 16-7. ................. . M.O.W.S. North Redvers No. X- 14-19.... . Imperia l Arm River Annandale No. 6-23 . .. California Standard Tidewater Carnoustie Province No. 4-20 .... .................................. Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Tiit~~~tC~~~:t~~ f~.~ ri~~ .'.~~~i~l····· ....... . Riddle Tidewater Clayridge No. 16-14............. . Neumann No. 12 .. . .... .. ....... ... ... ... ... . . . Tidewater Panamerica nWhite Bear No. 5-15 .... Canadian Devonian Tidewater Rupert No. 15,28 Riddle Tidewater Atwater No. 4-16....... .. Imperial Douglaston No. J2,6 ... ....... ... .. British American Canadian Devonian Quinn No. 9-34X ........................................... . Triton Tidewater Dubuc No. 15-22............. . Canadian Gulf Myrfield No. 12.......... . Tidewater Imperia l South Kisbey No. I. ..... . Texas Pacific South Rama No. 4-27 .............. . Imperial Halkett No. 15-7 ............................. . Imperia l Canadian Superior Stoughton No. 3-27 Husky Phillips Fitzmaurice No. I Imperial Hartaven No. 2, 1 Tidewater Beaverhills No. Canadian Gulf Margo No. 8-1 1............... . ....... . Texas Pacific Pig Lake No. 12,18........... ............ . Compagnie Francaise Des Petroles Outram No. Lsd Lsd Lsd Lsd Lsd Lsd Lsd 1-4-20,32wl... ..... . 16,14- 17-1 w2 .. . 12-29-2-2w2 .. . 5-t5- 10-2w2.. 15,28-12,2w2 4-16-20-2w2.... . 12-6,5-3w2 .. . 1666 1971 1722 2464 21 89 1722 1938 3912 4790 825.4 6794 6048 4253 7904 3995 4882 8355 6878 6140 4334 8008 4115 5001 8473 6999 6265 4454 8 125 4180 5072 8556 7079 6330 4520 8200 Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd 9-34-3-4w2 ..... . 15-22- 19,4w2 .. 12-18-32-5w2 16-34-7-6w2.... 4-27-31,7w2.... . 15-7-3,8w2 .... . 3-27,8,8w2...... . 16- 18-27-8w2 .. . 2-l l - 10-9w2 .. . 16-23-26-9w2... .. 8-11-33-9w2 ...... . I 2, t 8,34,9w2 .. 1935 1808 1688 2011 1765 1933 2058 2046 2054 2168 1845 1919 8311 4618 3103 7523 3410 9165 7606 4250 7258 4463 3420 3410 8419 471 8 3175 7630 3482 9265 7705 4346 7372 4548 3489 3487 8536 4845 3285 7750 3590 9384 7827 4452 7490 4658 3603 3600 8622 4909 3320 7832 3626 9484 7923 4484 7582 4699 3630 3628 1856 9146 9245 9360 9465 I Lsd 4,20,17-32wl ... . ~ ~ (feet above sea level ) Stonewall Formation (feet be, low K.B.) Lsd l- 19-3, 10w2.......... .. ""' I.I\ Shell Midale No. A-6-18 .................................. ...... Socony Star Blanket No. 1.................................. Imperial Kuroki No. 7-30...................................... Tidewater Foam Lake No. 1.................................. Shell Yeoman No. 6-32.......... ................................ Imperial Muscowpetung No. 1-9.......................... Tidewater Krasne No. 1.. .................................... Imperial Humm~bird No. 6-13 .................. ........ Imperial Herald o. l-31... ................................... Imperial Pangman No. 3-14.................................. Shell Big Muddy No. 1.......... ................................ Shell Fangman No. 1.............................................. Norcanols Parry No. 1.. ........................................ Sohio Socony Avonlea No. 1.. .............................. Socony Sohio Nokomis No. 29-10 ...................... Socony Sohio Hatfield No. 11- 14........................ Norcanols Ogema No. 1........................................ Amerada "S-AC" No. 13-16................................ Imperial Guernsey No. 13-34................................ Imperial Carville No. B-23 .................................... Amerada "S-AD" No. 13-12...... .......................... Woodley Mobil Horizon No. 11-34...................... Tidewater Stalwart No. 1... ............................. .... Pacific Mobil Harptree No. 1-28......................... . Socony Sohio North Ormiston No. 13-13 .......... Ceepee Baildon No. 2-11... ................................... Dillman Tuxford No. 1.. ........................................ Imperial Long Range No. 4-31.. .......................... Socony Sohio Verwood No. 1................................ Tidewater Allen bee & Associa tes Nash No. 1.. ... Richfield Killdeer No. 12-21... ............................. Imperial Constance No. 8-36.... ........................... Tidewater Bladworth No. 1.. .............................. Tidewater Eyebrow No. 2 .................................... Tidewater Allan No. 1.......................................... Johnstone Lake No. 1.. .... ................................... El Centro and Associates No. 12-35.................. Socony Sohio Strathallen No. 23-5 ...................... Tidewater Parkbeg No. 1.. ............... .... ............. .. Lsd Lsd Lsd Lsd Lsd Lsd Ls<l Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd Lsd 6-18-6,10w2............ 15-6-23-10w2.......... 7-30-34- 10w2.......... l-29-32-12w2.......... 6-32-B-16w2............ l-9-21-16w2.......... 16-14-30-16w2........ 6-13-2-19w2............ l-31-l-20w2............ 3-14-B-20w2............ 14-12-3-2lw2.......... 9-28-8-21 w2............ 16-8-9,21 w2............ 15-7- 12-21w2.......... 10-29-29-2lw2....... l l -14-28-22w2........ 4-24-7-23w2........... 13-16-14-23w2....... 13-34-33-23w2........ B-23-3-24w2............ 13-12-14-24w2... ..... l l-34-7-25w2.......... 14-10-27-25w2........ l-28-3-26w2............ 13-13-10-26w2....... 2-11-15-26w2......... l-3-19-26w2.......... 4-31-l-27w2............ 9-9-7-28w2............. l -17-27-28w2.......... 12-21-2-29w2......... B-36-3-29w2............ 16-36-27-29w2....... 5-30-23-1 w3........... 4-10-33-lw3 ........... 9-20-12-2w3 ............ 12-35-22-2w3.......... 5-23-2-3w3 .............. 10-32-18-3w3 .......... 2006 2206 1882 1776 1926 1994.6 2163 2458.5 2276 2212 2518 2489 2547 1942 1757 1718 2420 1870 1791 2524 1878 2536.5 1692 2749 2403 1937 1955 2734 2525 2010 2781.5 2844 2014 1917 1762 2421 1885 3026 2217 8355 5150 3455 3703 7715 5596 4525 9542 9310 7951 9170 (?) 8145 8060 (?) 6952 4591 4705 8120 (?) 6547 4240 8784 6374 8050 4909 8620 7500 6418 6081 8553 7780 5323 8337 8354 5262 5598 4567 6863 5620 8075 6262 8463 5247 3535 3782 7817 5682 4609 9647 9406 8055 9258 8243 8167 7043 4668 4788 8265 661 8 4331 8872 6462 8130 4978 8719 7585 6495 6158 8643 7850 5385 8421 8438 5322 5668 4624 6926 5689 8153 6339 8584 5355 3622 3885 7933 5789 4714 9765 9523 8165 9353 8367 8270 7158 4775 4888 8344 6720 4415 8980 6570 8250 5078 8840 7687 6612 6257 8753 7970 5489 8525 8523 5425 5772 4718 7003 5796 8260 6442 8675 5400 3658 3920 8038 5828 4751 9875 9629 8260 9497 8448 8370 7238 4804 4918 8442 68 15 4459 9069 6647 8304 5124 8910 7745 6670 6330 8830 8010 5526 8601 8631 5460 5812 4748 7050 5835 8332 6480 Well Name ~ British American Baciu No. 15-36...................... Quintana Melaval No. 1........................................ Sun Christie Gravelbourg No. 7-16................... . Stanolind Tidewater Wood River No. A-1 .......... Imperial Tidewater Strontield No. 12-16......... Tidewater Placid Hawar en No. I.. .................. Tidewater Dundum No. 2 .................................... Imperial Lawson No. 1.......................................... Imperial Morse No. !... ......................................... Tidewater Outlook No. 1.......... .............. ..... ....... Tidewater Birsay No. 1 ........................................ Tidewater Swanson No. 2........ ............................ Gulf Tidewater Vindeg No. 6 .............................. Tidewater Braddock No. 1.. .... ............................ Gulf Tidewater Sabine No. 9 ... ............................. Imperial Rossduff No. 4-2 ..... ......................... ... ... Amerada Shell "S-A" No. 5-31.. ...................... .... Shell Wood Mountain No. !... ............................. Gulf Tidewater Meaden No. 12............... ............. Tidewater Beechy No. I.. .................................... Shell Wood Mountain No. 2 ........ .... .... .... ............ Amerada Shell "S-E" No. 10-26.......................... lm~al Swift Current No. I.. ............................ Ti ewater Wymark No. 1....... ....... .......... ............ British American Wilhelm No. 1-9..................... Location Kelly Bushing Elevation (feet above sea level) Stonewall Formation (feet below K .B.) Stony Mtn. Formation (feet below K.B. ) 2531 2562 256 1 2308 2000 2014 1726 2214 2332 1776 2166 1753 2216 2654 2591 2129 2735 2544 2339 2411 2687 2691 2893 2788 2387 7356 7300 7218 6897 5427 5197 4675 6020 6385 4920 5749 4763 5939 6565 6601 5728 6627 6703 6079 6039 6522 6291 6702 6607 6003 7430 7362 7302 6967 5486 5253 4732 6125 6442 4980 5807 4832 5990 6661 6689 5822 6690 6783 6129 6093 6580 6349 6795 6697 6082 ·- - Lsd 15-36-6-4w3........... Lsd 2-14-8-4w3 ........... Lsd 7-16-9-4w3 ......... .. Lsd 4-18-10-4w3........... Lsd 12-16-26-4w3 ..... Lsd 12-10-29-5w3 ....... . Lsd 8-17-32-5w3 .. Lsd 16-13-21-6w3 Lsd l-6-18-7w3............ Lsd 7-20-30-7w3 .. .. Lsd 13-4-25-8w3 ....... Lsd 16-9-32-8w3............ Lsd 6-28-22-9w3 ............ Lsd 5-7-14-10w3 ............ Lsd 9-27-14-!0w3......... Lsd 4-2-24-10w3 ........... Lsd 5-31-2-llw3........... Lsd 7-34-9-11 w3 ........... Lsd 12-35-21-11 w3 ...... Lsd l-29-23-llw3 .......... Lsd 13-36-1-12w3.......... Lsd 10-26-l-13w3.......... Lsd 11-20-13-13w3....... Lsd 3-10-14-14w3.......... Lsd l-9-17-14w3 ............ Red River Formation (feet below K.B.) Herald Yeoman Member Member I 7540 7449 7374 7041 5589 5356 4832 6190 6545 5081 5898 4932 6093 6730 6748 5880 6749 6857 6241 6198 6630 6436 6853 6755 6132 7594 7545 7470 7125 5630 5396 4872 6240 6600 5122 5942 4958 6135 6180 6814 5936 6804 6902 6275 6241 6690 6495 6898 6796 6 172 RECINA, SASKATCHEWAN Printed by LAWRENCE AMON, Printer to the Queen's Most Excellent Majesty. 1959 ~ ·