- Mineralogical Society of America
... Porosity in intact bedrock is comprised of inter- and intra-granular pores developed during (re-) crystallization in igneous and metamorphic rocks or diagenesis in sedimentary rocks. As ...
... Porosity in intact bedrock is comprised of inter- and intra-granular pores developed during (re-) crystallization in igneous and metamorphic rocks or diagenesis in sedimentary rocks. As ...
A Pictorial Guide to Metamorphic Rocks in the Field
... planes of easy breaking. These are controlled by planes of particularly weak atomic bonds in the crystal lattice, spaced at an atomic scale. For rocks, cleavage in its most primitive sense refers to similar parallel-aligned planes or curved surfaces along which the rock breaks easily. Slate (Fig. 2. ...
... planes of easy breaking. These are controlled by planes of particularly weak atomic bonds in the crystal lattice, spaced at an atomic scale. For rocks, cleavage in its most primitive sense refers to similar parallel-aligned planes or curved surfaces along which the rock breaks easily. Slate (Fig. 2. ...
GSA TODAY - Geological Society of America
... mafic-to-ultramafic crust of oceanic character lying depositionally beneath the western flank of the Great Valley forearc basin in fault contact with the Franciscan subduction complex of the California Coast Ranges. Three contrasting hypotheses for genesis of the ophiolite as seafloor are each based ...
... mafic-to-ultramafic crust of oceanic character lying depositionally beneath the western flank of the Great Valley forearc basin in fault contact with the Franciscan subduction complex of the California Coast Ranges. Three contrasting hypotheses for genesis of the ophiolite as seafloor are each based ...
Intrusive igneous rocks include granite.
... The Appalachian Plateau has rugged irregular topography and is underlain by ancient, flat-lying sedimentary rocks. The area is actually a series of plateaus separated by faults. Most of Virginia’s coal resources are found in the plateau ...
... The Appalachian Plateau has rugged irregular topography and is underlain by ancient, flat-lying sedimentary rocks. The area is actually a series of plateaus separated by faults. Most of Virginia’s coal resources are found in the plateau ...
THE AGUABLANCA Ni–Cu–PGE DEPOSIT, SOUTHWESTERN
... The Aguablanca Ni–Cu–PGE ore deposit, in southwestern Iberia, has a magmatic origin, and has been reworked by later skarn-related hydrothermal activity. Base-metal sulfides are associated with igneous cumulates displaying subvertical layering consisting of gabbro, norite and dolerite, with fragments ...
... The Aguablanca Ni–Cu–PGE ore deposit, in southwestern Iberia, has a magmatic origin, and has been reworked by later skarn-related hydrothermal activity. Base-metal sulfides are associated with igneous cumulates displaying subvertical layering consisting of gabbro, norite and dolerite, with fragments ...
emplacement of viscous mushes in the jinchuan ultramafic
... net-textured and massive sulfide ore grading 1.06% Ni and 0.7% Cu, outcrops as an elongate body, 6500 m long, usually less than 500 m wide and more than 1100 m deep in its central part (Fig. 2). It intruded marble, migmatite and gneiss of the Baijiazuizi Formation and has a Sm–Nd isochron age of 1.5 ...
... net-textured and massive sulfide ore grading 1.06% Ni and 0.7% Cu, outcrops as an elongate body, 6500 m long, usually less than 500 m wide and more than 1100 m deep in its central part (Fig. 2). It intruded marble, migmatite and gneiss of the Baijiazuizi Formation and has a Sm–Nd isochron age of 1.5 ...
Differential preservation in the geologic record of intraoceanic arc
... of the forearc width, compared to b25% at tectonically eroding margins (Scholl and von Huene, 2010). The tectonic-erosion model thus proposes a fairly constant forearc width, in which individual packages of rock migrate closer to the trench as ongoing tectonic erosion progressively strips material f ...
... of the forearc width, compared to b25% at tectonically eroding margins (Scholl and von Huene, 2010). The tectonic-erosion model thus proposes a fairly constant forearc width, in which individual packages of rock migrate closer to the trench as ongoing tectonic erosion progressively strips material f ...
Muntean/Einaudi - Nevada Bureau of Mines and Geology
... episodes of mostly andesitic to dacitic arc magmatism occurred in the Maricunga belt from the late Oligocene to the early Pliocene (Kay et al., 1994; Mpodozis et al., 1995). The first (26–20 Ma, late Oligocene to early Miocene) and second (16–11 Ma, middle Miocene) episodes resulted in numerous stra ...
... episodes of mostly andesitic to dacitic arc magmatism occurred in the Maricunga belt from the late Oligocene to the early Pliocene (Kay et al., 1994; Mpodozis et al., 1995). The first (26–20 Ma, late Oligocene to early Miocene) and second (16–11 Ma, middle Miocene) episodes resulted in numerous stra ...
The Skaergaard Layered Series. Part II
... define the extent and trajectories of magmatic flow and thereby lead to a better understanding of internal processes during cooling and crystallization. Recent studies of the layered rocks of the Oman Ophiolite, for example, have revealed that the gabbros have been intensely deformed while in the ma ...
... define the extent and trajectories of magmatic flow and thereby lead to a better understanding of internal processes during cooling and crystallization. Recent studies of the layered rocks of the Oman Ophiolite, for example, have revealed that the gabbros have been intensely deformed while in the ma ...
Mesozoic tectonics of the Maria fold and thrust belt and McCoy basin
... events related to the Mesozoic Cordilleran Orogeny in southeastern California. The Maria Fold and Thrust Belt (MFTB) is an east-west trending belt of amphibolite grade metamorphic rocks characterized by largely south-vergent folds and ductile shear zones that place Jurassic and Proterozoic crystalli ...
... events related to the Mesozoic Cordilleran Orogeny in southeastern California. The Maria Fold and Thrust Belt (MFTB) is an east-west trending belt of amphibolite grade metamorphic rocks characterized by largely south-vergent folds and ductile shear zones that place Jurassic and Proterozoic crystalli ...
Geological Survey of Denmark and Greenland Map Series 2
... Frontispiece. The historical and logistical centre of the Thule region around North Star Bugt, Bylot Sund, in the central part of the Thule map sheet. Above: Thule Air Base located in the broad Quaternary-filled valley and now called Pituffik after the valley and river Pituffiup Kuussuaq (visible t ...
... Frontispiece. The historical and logistical centre of the Thule region around North Star Bugt, Bylot Sund, in the central part of the Thule map sheet. Above: Thule Air Base located in the broad Quaternary-filled valley and now called Pituffik after the valley and river Pituffiup Kuussuaq (visible t ...
Petrology and structure of syenite intrusions of the Okenyenya
... grained syenite. A narrow screen of highly altered gabbro partially separates the plug from the continuation of the ring dyke. To the north, the ring dyke narrows in exposures on the steep western flank of Okenyenya Berg before being truncated by the younger nepheline syenite intrusion. The dyke als ...
... grained syenite. A narrow screen of highly altered gabbro partially separates the plug from the continuation of the ring dyke. To the north, the ring dyke narrows in exposures on the steep western flank of Okenyenya Berg before being truncated by the younger nepheline syenite intrusion. The dyke als ...
Continental Growth and Recycling in Convergent Orogens with
... Widespread magmatism in the western part of the WLO at ~400 Ma was followed by final closure of the marginal basin, which was thrust over the northeastern part of the Tasmanian microcontinent by about 390 Ma (Figure 8f). Structural thickening and amalgamation of the WLO and CLO led to cratonization ...
... Widespread magmatism in the western part of the WLO at ~400 Ma was followed by final closure of the marginal basin, which was thrust over the northeastern part of the Tasmanian microcontinent by about 390 Ma (Figure 8f). Structural thickening and amalgamation of the WLO and CLO led to cratonization ...
Batholith tectonics: Formation and deformation of ghost stratigraphy
... schists, conglomerates, and calc-silicate rocks that unconformably overlie fragmented ultramafic bodies (Heldal, 1987, 2001; Heldal and Hjelmeland, 1988; Yoshinobu et al., 2002). The age of deposition of this unit is determined to be Ordovician based on a detrital zircon date of 481.7 ± 2.5 Ma from ...
... schists, conglomerates, and calc-silicate rocks that unconformably overlie fragmented ultramafic bodies (Heldal, 1987, 2001; Heldal and Hjelmeland, 1988; Yoshinobu et al., 2002). The age of deposition of this unit is determined to be Ordovician based on a detrital zircon date of 481.7 ± 2.5 Ma from ...
The anatomy and ontogeny of modern intra
... systems and have been the most important sites of juvenile continental crust formation for as long as plate tectonics has operated. IOASs’ crustal profiles are wedge-shaped, with crust up to 20–35 km thick; a more useful definition is that IOASs occur as chains of small islands, generally just the t ...
... systems and have been the most important sites of juvenile continental crust formation for as long as plate tectonics has operated. IOASs’ crustal profiles are wedge-shaped, with crust up to 20–35 km thick; a more useful definition is that IOASs occur as chains of small islands, generally just the t ...
Synthesis of Results From the CD-ROM Experiment
... oceanic terranes in the Paleoproterozoic. Crustal provinces with different geologic histories correspond to distinct mantle velocity domains, with profound mantle velocity contrasts associated with the ancient sutures. Typically, the transitions between the velocity domains are tabular, dipping, ext ...
... oceanic terranes in the Paleoproterozoic. Crustal provinces with different geologic histories correspond to distinct mantle velocity domains, with profound mantle velocity contrasts associated with the ancient sutures. Typically, the transitions between the velocity domains are tabular, dipping, ext ...
appendix 2 - Rockmass.net
... material with relatively small amounts of clay to highly weathered or hydrothermally altered, highly plastic, swelling clay gouge. The composition of these pieces can be similar to the adjacent rock, or hydrothermal solutions can have altered the original rock material and/or brought in and deposite ...
... material with relatively small amounts of clay to highly weathered or hydrothermally altered, highly plastic, swelling clay gouge. The composition of these pieces can be similar to the adjacent rock, or hydrothermal solutions can have altered the original rock material and/or brought in and deposite ...
Field Guide Book - Department of Geography - Geology
... footing and be aware of people below you. If you loosen a rock on a slope, yell “ROCK!” loudly to warn those below. ...
... footing and be aware of people below you. If you loosen a rock on a slope, yell “ROCK!” loudly to warn those below. ...
GEOLOGICAL SURVEY OF FINLAND Special Paper 48 2008 GTK
... Explanation Volume 1 covers the whole of southern Mozambique. Only in the northwestern corner of this mapping area, south of Manica, are Proterozoic rocks exposed, while by far the majority of the area is covered by Phanerozoic units, from Karoo sediments and volcanics to extensive Cretaceous – Tert ...
... Explanation Volume 1 covers the whole of southern Mozambique. Only in the northwestern corner of this mapping area, south of Manica, are Proterozoic rocks exposed, while by far the majority of the area is covered by Phanerozoic units, from Karoo sediments and volcanics to extensive Cretaceous – Tert ...
Origin of Mesoproterozoic A-type granites in Laurentia
... compositions reflect the relative contributions of mantle and crustal sources in their genesis. In Laurentia, a distinctive belt of Mesoproterozoic A-type or “anorogenic” granites of ∼ 1.4 Ga age was emplaced within composite, heterogeneous Proterozoic crust. Zircons are an ideal mineral to constrai ...
... compositions reflect the relative contributions of mantle and crustal sources in their genesis. In Laurentia, a distinctive belt of Mesoproterozoic A-type or “anorogenic” granites of ∼ 1.4 Ga age was emplaced within composite, heterogeneous Proterozoic crust. Zircons are an ideal mineral to constrai ...
Chapter 21: Metamorphism
... s1 > s2 = s3 foliation and no lineation s1 = s2 > s3 lineation and no foliation s1 > s2 > s3 both foliation and lineation Figure 21-3. Flattening of a ductile homogeneous sphere (a) containing randomly oriented flat disks or flakes. In (b), the matrix flows with progressive flattening, a ...
... s1 > s2 = s3 foliation and no lineation s1 = s2 > s3 lineation and no foliation s1 > s2 > s3 both foliation and lineation Figure 21-3. Flattening of a ductile homogeneous sphere (a) containing randomly oriented flat disks or flakes. In (b), the matrix flows with progressive flattening, a ...
granites of the lachlan fold belt
... Australian continent and it has a total area of close to 300,000 km2. There was very extensive igneous activity in the LFB in Silurian and Devonian times, and during the Carboniferous in the northeastern corner of the belt. Massive quantities of granitic magma were produced and we currently recognis ...
... Australian continent and it has a total area of close to 300,000 km2. There was very extensive igneous activity in the LFB in Silurian and Devonian times, and during the Carboniferous in the northeastern corner of the belt. Massive quantities of granitic magma were produced and we currently recognis ...
the mississippian barnett formation
... In outcrops, the Chappel Formation consists of light-colored, fine to coarse grained, skeletal packstone (Watson, 1980). Although ostracodes, corals, and other fossils are common, it is the abundance of crinoids, in many cases red, that distinguishes the Chappel. The thickness of the Chappel is typ ...
... In outcrops, the Chappel Formation consists of light-colored, fine to coarse grained, skeletal packstone (Watson, 1980). Although ostracodes, corals, and other fossils are common, it is the abundance of crinoids, in many cases red, that distinguishes the Chappel. The thickness of the Chappel is typ ...
Late Sveconorwegian monzonitic dykes in the Setesdalen areaof
... two components are clearly separated, with the monzonite lying below the granite, but often a zone of hybrids have formed between the two. A huge number of small, fine-grained monzonite and/or granite-aplite intrusions are either emplaced into the larger plutons, or are found in their vicinity, indi ...
... two components are clearly separated, with the monzonite lying below the granite, but often a zone of hybrids have formed between the two. A huge number of small, fine-grained monzonite and/or granite-aplite intrusions are either emplaced into the larger plutons, or are found in their vicinity, indi ...
20 Crystallization, Fractionation and Solidification of Co
... olivine and calcic plagioclase, together with non-silicate minerals, b) medium-silica-bearing minerals, such as clinopyroxene or labradorite, c) high silica-bearing minerals, such as orthoclase and quartz. Depending on the initial chemical composition of the common basaltic magma, either plagioclase ...
... olivine and calcic plagioclase, together with non-silicate minerals, b) medium-silica-bearing minerals, such as clinopyroxene or labradorite, c) high silica-bearing minerals, such as orthoclase and quartz. Depending on the initial chemical composition of the common basaltic magma, either plagioclase ...
Geology of Great Britain
The geology of Great Britain is renowned for its diversity. As a result of its eventful geological history, Great Britain shows a rich variety of landscapes across the constituent countries of England, Wales and Scotland. Rocks of almost all geological ages are represented at outcrop, from the Archaean onwards.