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STANFORD PROJECT ON DEEP-WATER DEPOSITIONAL SYSTEMS
23rd Annual Meeting and Field Workshop
DEATH VALLEY, CALIFORNIA
Field Guide:
Upper Paleozoic Deep-Water Passive Margin Sequences
of the Death Valley Region
October 25-29, 2015
Department of Geological Sciences
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Stanford University
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WELCOME
Welcome to all of the participants on the SPODDS 2015 Field Trip to
Death Valley, California. The area of Death Valley National Park is one of the
most scenic and geologically spectacular areas in the world and a superb venue
for our meeting and field excursion.
On this trip, we will have the opportunity to review the graduate-student
SPODDS research currently underway at Stanford and meet a number of new
students admitted to PhD and MS study in 2015. On several days, we will leave
the hotel and go on field trips. The main units to be visited include mixed
siliciclastic-carbonate turbidites and debris-flow deposits of the Pennsylvanian
Keeler Canyon Formation and Permian Darwin Canyon Formation. These and
related units were deposited off of the Late Paleozoic continental margin of
western North America, are exposed only in small, isolated areas in the region,
and are structurally complex and locally metamorphosed. We will examine
classic sections where sedimentary features, sedimentation units, and larger-scale
packaging can be seen.
We will also able be able to examine the classic alluvial fans developed
throughout the Death Valley region, most notably the well-known, small alluvial
fans along the eastern side of Death Valley between Furnace Creek and
Badwater. We will also see and explore the South Dolomite fan along the east
side of Owens Valley and examine and discuss these alluvial fans and their
relevance to understanding processes and deposits on deep-water fans.
If time is available, we will also visit the explosive volcanic crater,
Ubahebe Crater, and the famous sliding stones of Racetrack Playa.
This guidebook will provide a framework for understanding the various
units and outcrops to be seen on the trip. There is a rich literature beyond the
articles discussed and referenced here for anyone interested in exploring further
the geology of the Death Valley area.
Again, welcome to all of the participants on this field trip. We hope that it
will be a rewarding scientific and cultural experience for all.
Donald R. Lowe
Steve Graham
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CONTENTS
CONTENTS .
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GEOLOGIC MAP OF DEATH VALLEY NATIONAL PARK
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FIELD TRIP SCHEDULE .
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DAY 1: DRIVE FROM STANFORD TO DEATH VALLEY .
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Late Precambrian and Paleozoic: Pre-rift and passive margin .
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Mesozoic to Early Cenozoic: Convergent margin
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Middle to Late Cenozoic: San Andreas faulting and extension
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DAY 2: DARWIN CANYON: DEEPWATER UNITS OF THE DARWIN
CANYON FORMATION .
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Road Log for Trip to Darwin Canyon
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STOP 2-1: Darwin Canyon .
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Road Log for Trip to South Dolomite Fan
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STOP 2-2: South Dolomite Fan
DAY 3: MEETING and TALKS .
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DAY 4: UBEHEBE MINE SECTION OF THE DEEPWATER KEELER
CANYON FORMATION .
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Road Log for Trip to Ubehebe Mine
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STOP 4-2: Ubehebe Mine and Keeler Canyon Formation
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Road Log for Trip to Racetrack Playa
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STOP 4-3. Racetrack Playa .
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DAY 5: ALLUVIAL FANS
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Road Log: Furnace Creek Ranch to Warm Spring Canyon fan
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Alluvial Fans and Fan Deltas
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Fig. 1. General geologic map of Death Valley (from marlimillerphoto.com).
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FIELD TRIP SCHEDULE
DAY 1: Sunday, October 25, 2015: Drive to Death Valley
8:00 AM - 5:00 PM
Students drive to Death Valley, arriving at the Furnace Creek
Ranch Resort in early evening to check in. It is about 450 miles
(724 km) from Palo Alto to Death Valley and the trip will
probably take about 9-10 hours with meals and gas stops.
6:00 PM
Evening social at the Corkscrew
DAY 2: Monday, October 26, 2015: Drive from Death Valley to Owens Valley. We
will examine Permian deepwater turbidies and debris flow deposits of the Darwin
Canyon Formation and modern debris-flow deposits on South Dolomite Fan
8:00 AM
Meet with vehicles in the parking area in front of the Furnace
Creek Ranch
8:00 AM-9:00 AM
Drive to Darwin Canyon
9:00 AM-12:00
Examine outcrops of the Permian Owens Valley
Group in Darwin Canyon
1:00-2:00 PM
Drive to South Dolomite alluvial fan near Lone Pine, CA
2:00-4:00 PM
Examine debris-flow deposits on Dolomite fan
4:00-5:30 PM
Drive back to the Furnace Creek Ranch
DAY 3: Tuesday, October 27, 2015: Meeting and SPODDS student presentations.
7:45 AM
Meet with vehicles in the parking area in front of the Furnace
Creek Ranch. We will drive up the hill to the Furnace Creek
Resort.
8:00 AM - 5:00 PM
Meeting in the Marquez Room in the Furnace Creek Resort.
6:00 PM
Social in the Corkscrew
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DAY 4: Wednesday, October 28, 2015: Field trip to mixed siliciclastic and
carbonate deep-water deposits in the Pennsylvanian Keeler Canyon Formation. This
will involve a substantial hike, about 6-8 miles round trip down a long, low-gradient
but gravel-bed gully, then back. There will be a couple of places where we have to
scramble down some rocky drop-offs. Bring appropriate field gear to be away from
the cars, hiking for most of the day.
8:00 AM
Meet with vehicles in the parking area in front of the Furnace
Creek Ranch
8:00 AM-9:30 AM
Drive via Ubehebe Crater to Ubehebe Mine north of
Racetrack Playa
9:30 AM-4:00 PM
Hike to examine the Pennsylvanian Keeler Canyon Formation
and underlying Paleozoic carbonate units.
4:00-5:00
Sliding stones of racetrack Playa
5:00-6:00 PM
Return to Furnace Creek Ranch
DAY 5: Thursday, October 29, 2015: Field trip in Death Valley to view modern
alluvial fans and playa sediments and discuss features related to modern tectonism
and the formation of the Valley.
7:45 AM
Check out of the hotel, collect your luggage, pack in the
vehicles, and meet with the loaded vehicles in the parking area
in front of the Furnace Creek Ranch.
8:00-12:00
Drive south to/through Badwater to examine modern alluvial
fans along the east side of Death Valley. We will compare fans
dominated by fluid flows (sheet flows) and adjacent fans
dominated by debris flows.
12:00 - 12:30 PM
Group lunch as Badwater. Walk out on evaporitic playa
deposits, if possible.
12:30 PM
Field Trip and SPODDS meeting over. Head back to airports for
return home.
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DAY 1: DRIVE FROM STANFORD TO DEATH VALLEY
October 25, 2015
The trip from Stanford to Death Valley (Fig. 1-1) will take us across some
of the most interesting and complex geology in the United States. What follows
here is a brief outline of that geology and the events that formed it.
The physiography, geologic provinces, and general geology of California
are shown on the maps in Figs. 1-2 and 1-3. The course of our field trip takes us
through a number of major geologic provinces and through much of Phanerozoic
and Late Precambrian geologic time. The geologic development of central
California can be divided into three major intervals; (1) the Late Precambrian and
Paleozoic, during which time the Death Valley area in California lay along the
western, largely passive margin of the North American Craton, (2) the Mesozoic
and earliest Cenozoic, when California was part of a convergent margin and
dominated by a complex of volcanic arcs and accretionary events that built the
continent westward, and (3) the middle and late Cenozoic, when western
California was dominated by the San Andreas Fault system and eastern
California by extension and the formation of the Basin and Range province. Each
of these major intervals will be described briefly below.
Late Precambrian and Paleozoic: Pre-rift and passive margin
The earliest record of geologic events in California lies in the basement
rocks in the Death Valley region. This basement is 1.8-1.7 Ga (billion years old)
and composed of metamorphic rocks representing a complex of sedimentary and
volcanic terrains that amalgamated to form this part of the North American
Craton. These rocks are exposed in mountains ranges throughout the Death
Valley region, the Mojave Desert, and the bottom of the Grand Canyon. Over
most of the area, however, they are covered by younger sedimentary and
volcanic units.
The present-day western extent of this basement (Fig. 1-4A) marks the
western edge of the Precambrian North American Craton. This continental
margin formed during the Late Precambrian by rifting of a supercontinent. The
vanished western block may now be represented in Australia or eastern Asia.
Rifting was preceded by a number of tectonic events along the trend of the future
rift, including the formation of a basin that has been called the Amargosa
Aulacogen (Fig. 1-4B, 1-5, and 1-6) starting at about 1.2 Ga and possibly
continuing to as late as 800 Ma. The sediments deposited in this aulacogen in the
Death Valley area belong to the Pahrump Group (Fig. 1-5) and include, from base
to top, the Crystal Spring, Beck Spring, and Kingston peak Formations. We will
examine the Kingston Peak, which includes glacial deposits formed during the
Sturtian glaciation at about 750-700 Ma. The Kingston Peak glacial units are
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overlain by the Noonday Dolomite, which is through to represent a cap
carbonate. Cap carbonates were deposited following major glacial periods when
the warming of the world's oceans forced the rapid deposition of carbonate
sediments.
Fig. 1-1. Road map showing the route of the drive from Stanford to Furnace
Creek in Death Valley.
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Fig. 1-2. Physiographic map of California showing the field trip route. The low
areas are in green and higher elevations in brown. The two most prominent
features are the NNW-trending Great Valley and adjacent Sierra Nevada
mountains.
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Fig. 1-3. (A) Geologic map of California. The main colors are: Precambrian
basement (brown), Upper Precambrian and Paleozoic sedimentary rocks (blue),
Mesozoic sedimentary rocks (light green), Triassic and Jurassic volcanic and
metamorphic rocks (dark green), Mesozoic, mostly Cretaceous, plutonic rocks
(red), Cenozoic sedimentary rocks (yellow), and Cenozoic volcanic rocks (pale
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pink) (from geology.about.com). (B) Major geologic provinces of California (from
consrv.ca.gov). Field trip route in black.
The overlying Johnnie, Stirling, and Wood Canyon Formations (Fig. 1-5)
form a thick succession of uppermost Precambrian and lower Cambrian, largely
siliciclastic strata that were deposited more-or-less concurrent with rifting to
form the western, passive margin of North America. The main axis of rifting
must have been located somewhat farther west and north inasmuch as these
formations in the Death Valley area form a generally concordant section of
fluvial to shallow marine strata and do not show features or sedimentology
consistent with deposition in rift basins. The overlying Carrara and very thick
Bonanza King Formations of Middle to Late Cambrian age mark the thermal
subsidence stage of rifted margin evolution.
From Cambrian through the Permian, the Death Valley area persisted as a
passive continental margin (Fig. 1-4B), accumulating a variety of largely shallow
water carbonate and mature siliciclastic units. Father north from the Death
Valley area in central and northern Nevada, there were periods of deformation in
the Devonian and later Paleozoic (Fig. 1-7) marking the collision of offshore
Pacific arc terranes with the passive margin. These are evidenced by the
thrusting of more oceanic type sedimentary packages up onto the edge of the
passive margin sequence during the Antler Orogeny and the presence of arcrelated volcanic-sedimentary terranes in the northern Sierra Nevada and
Klamath Mountains.
In the Death Valley area, locally preserved upper Paleozoic mixed
siliciclastic and carbonate deepwater sections represent the more offshore parts
of the continental margin sequence, perhaps in part deposited in foredeeps to the
older Antler origenic belt (Fig. 1-7). We will examine the Mississippian Keeler
canyon Formation near the Ubehebe Mine and the Pennsylvanian Darwin
Canyon Formation about 50 miles west of the Park. Both provide a glimpse of the
deepwater system that must have flanked the North American Craton to the
west throughout most of its development in the Paleozoic.
The close of the Paleozoic saw the vanishing of marine conditions over
much of western North America, including the Death Valley region. There are
only local Triassic sections preserved and the subsequence Jurassic and
Cretaceous were marked by volcanism, intrusion, and uplift with few
sedimentary deposits preserved in the Death Valley region.
Mesozoic to Early Cenozoic: Convergent margin
Major preserved sedimentary and volcanic sequences representing
Mesozoic and early Tertiary events in California lie west of the Death Valley
region. This period saw the development of a series of long-lived north-south
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trending volcanic arcs and subduction zones along the western margin of present
day North America (Figs. 1-8, 1-9, and 1-10) associated the break-up of the
supercontinent Pangea in latest Paleozoic and subsequent dispersal of the
various continental fragments. Volcanic arcs, represented today by granitoid
batholiths and xenoliths of intermediate volcanic-sedimentary rock assemblages,
formed as early as Triassic (?) or Jurassic time and persisted until the early
Tertiary. They are marked by a broad belt of plutonic rocks extending from Baja
California in Mexico up the Sierra Nevada, into northern Nevada, Idaho, and
Canada (Fig. 1-9 and 1-10). The forearc, trench, and subduction settings lying
west of the arc crop out from the western foothills of the Sierra Nevada to the
California coast ranges. This series of subduction zones stepped progressively to
the west over time and the last major complex formed from late Jurassic to early
Tertiary time. It is represented by 5 major geologic provinces and features that to
this day dominate the physiography of western and central California (Fig. 1-2,
1-3, and 1-8): (1) the uplifted accretionary wedge/subduction complex of the
California Coast Ranges, called the Franciscan Complex, representing oceanic
crustal rocks and overlying oceanic and trench sediments scraped off the
subducted plate; (2) the eastward-dipping subduction zone and overlying mantle
wedge, represented by a narrow zone of serpentine and ultramafic rock marking
the Coast range Ophiolite or Coast Range Thrust lying mainly along the eastern
edge of the Franciscan Complex; (3) the structurally overlying Great Valley
Supergroup, representing the Upper Jurassic, Cretaceous, and earliest Tertiary
forearc basin sedimentary sequence lying just east of the Coast Range Ophiolite
and which, before deformation was deposited in part on the mantle wedge above
the subduction zone; (4) the Great Valley of central California, representing the
remnant forearc basin and buried western edge of the volcanic arc; and (5) the
Sierra Nevada, representing the tilted and uplifted volcanic arc basement (Fig. 18). These component parts of the Late Mesozoic convergent junction have been
fragmented and disturbed by subsequent geologic events but, to this day,
dominate the topography and geology of central California as far east as the
eastern edge of the Sierra Nevada.
The Cretaceous was also one of the major episodes of plutonic activity
known. The entire circum-Pacific region saw the intrusion of enormous volumes
of tonalitic to granitic magmas during the Cretaceous. These are represented
today by outcropping plutonic complexes in the Sierra Nevada and Peninsular
ranges of California as well as throughout adjoining areas in the western United
States, Mexico, and Canada, (Fig. 1-9). A major episode of faulting and folding
termed the Sevier Orogeny marked the development of a back-arc fold-and
thrust belt over much of the area underlain by the old Paleozoic passive margin
sequence in the Late Jurassic and Cretaceous (Figs. 1-10 and 1-11).
Middle to Late Cenozoic: San Andreas faulting and extension
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We will start the field trip at Stanford within a couple of miles of the San
Andreas Fault. This enormous geologic feature, which runs from the Gulf of
California in Mexico on the south to the Pacific coast of northern California,
marks the boundary between the Pacific Plate to the west and the North
American Plate to the east (Fig. 1-12). While a sharp and linear feature along
most of its length, the zone of shearing associated with the movement of these
two plates past one another extends as far west as Nevada, several hundred
miles from the San Andreas Fault itself (Fig. 1-12).
San Andreas activity started in the middle Tertiary (Miocene) and the
fault has grown to the north and south and remains the dominant geologic
feature of western California to this day. While most of the rocks exposed in the
Coast Ranges and Sierra Nevada were formed during the Mesozoic convergent
margin stage of evolution, most of their structure and uplift have originated
during younger Cenozoic time. While driving down the western side of the
Great Valley on our way from Stanford to Bakersfield, we will pass some of the
largest oilfields in California in the San Joaquin Valley. This oil is housed mainly
in Eocene, Miocene, and Pliocene sediments within anticlines, some of which are
actively deforming today, developed because the San Andreas is not a perfect
strike-slip fault but is a transpressional fault that is also causing shortening and
folding in the adjacent rocks.
On the east side of the Sierra Nevada lies another major Cenozoic geologic
province, the Basin and Range Province (Fig. 1-9). Starting in the Early Miocene,
about 17 Ma, this area began to extend and that extension is still going on locally
today. The result has been extensive silicic volcanism and the formation of a
broad belt of block faulted crust characterized by alternating mountain ranges,
representing horsts, and valleys, representing down-dropped blocks or grabens,
which are partially filled by young alluvial sediments. The Death Valley region
lies in the western Basin and Range but is also within a zone of strike-slip
faulting related to the San Andreas Fault (Fig. 1-9). Hence, Death Valley is both a
graben related to extension and a pull-apart basin associated with strike-slip
activity. In Death Valley and many areas in the Basin and Range, extension has
been so extreme that thinning of the upper crust has cause uplift of deeper-level
metamorphic rocks to form what-are-called metamorphic core complexes that
expose very deep-level, high-grade metamorphic rocks at the surface. These
uplifted complexes have been called "turtlebacks" in the Death Valley area for
their smooth, rounded, arch-like surfaces, which represent the uplifted normal
faults. The Black Range immediately east of Badwater in Death Valley is such a
turtleback composed of a metamorphic core complex.
On our trip, we will traverse rocks representing all of these major stages in
the geologic evolution of California. We will have maps and literature along that
will help to explain these provinces and events further for anyone interested.
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References
Levy, M., and Christie-Blick, N., 1991, Tectonic subsidence of the early Paleozoic
passive continental margin in eastern California and southern Nevada: GSA
Bulletin, v. 103, p. 1590-1606.
Yose, L.A., and Heller, P.L., 1989, Sea-level control of mixed-carbonatesiliciclastic, gravity-flow deposition: Lower part of the Keeler Canyon
Formation (Pennsylvanian), southeastern California: GSA Bulletin, v. 101, p.
427-439.
Fig. 1-4. (A) Distribution of Precambrian basement rocks in the western United
States. The area in pink is not known to contain any Precambrian basement. This
western margin of North American Precambrian basement formed during rifting
in latest Precambrian time. (B) Late Precambrian and Paleozoic depositional
settings in the western United States. The Amargosa Aulacogen was active
during Precambrian time and sediments inferred to have been deposited in this
basin belong to the Pahrump Group (Fig. 1-5). The passive continental margin
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accumulated a thick succession of largely shallow water carbonate and
siliciclastic sediments that is widely exposed in the Death Valley area.
Fig. 1-5. Stratigraphic column of Upper Precambrian and Lower Paleozoic rocks
exposed in the Nopah Range, southern Death Valley area, showing the
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relationship between tectonic settings and depositional sequences (from Levy
and Christie-Blick, 1991).
Fig. 1-6. Cross-section through the southern Death Valley area showing the
westward thickening of the Upper Precambrian and Paleozoic continental
margin sequence (from http://www.nap.edu/openbook.php?record_id=2013).
Fig. 1-7. Main Pennsylvanian and Late Paleozoic tectonic elements during
deposition of the Keeler Canyon Formation. The Antler Orogenic Belt formed by
the thrusting of more western, deepwater sedimentary rocks onto the western
edge of the North American passive margin. The resulting Antler highland shed
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debris to the east into the foreland basin. The Death Valley region lay largely to
the south of this zone of uplift and deformation (from Yose and Heller, 1989).
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Fig. 1-8. Main elements of the convergent margin that developed along the
western margin of North America during the Mesozoic. The Death Valley area
was located east of the Sierra Nevada arc along the eastern edge of this diagram
(from nobear.colorado.edu)
Fig. 1-9. Distribution of Jurassic and Cretaceous plutonic rocks in the western
United States (from geog.ucsb.edu).
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Fig. 1-10. Summary of main tectonic elements in the western US during Late
Paleozoic and Mesozoic time. Shallow water Upper Precambrian and Paleozoic
continental margin deposits were overridden by thrust masses of more offshore,
deeper water sediments during the Devonian to form the Antler orogenic belt.
During the Cretaceous, The Sevier Orogeny formed an eastward-verging, backarc fold and thrust belt across much older continental margin while large
amounts of plutonic magmas were intruded along the arc trend. To the west lay
the trench and forearc regions.
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Fig. 1-11. Summary of the Cretaceous to mid-Cenozoic tectonic development of
the western United States showing the changing character of subduction. After
about 35 million years ago, subduction ceased along the newly-formed boundary
between the North American and Pacific Plates, which became the San Andreas
transform fault (from geoinfo.nmt.edu).
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Fig. 1-12. Major Late Cenozoic tectonic zones in the western US. The San
Andreas Fault system dominates in western California. East of the Sierra
Nevada, a broad area of extension, the Basin and Range Province, has also seen
the development of a number of broad shear zones related to movement along
the San Andreas system, including the Eastern California Shear Zone in the
Death Valley area (from http://geology.csupomona.edu/docs/stop2-3.htm).
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DAY 2: DARWIN CANYON: DEEPWATER UNITS OF THE
DARWIN CANYON FORMATION
October 26, 2015
We will leave from the parking lot at Furnace Creek Ranch at 8:00 am.
From Furnace Creek Ranch, we will drive north and then west on California
Hwy. 190 through Stovepipe Wells and Panamint Valley about 70-80 miles to the
junction with the road to the town of Darwin (Fig. 2-1). The road log from this
junction to the outcrops in Darwin Canyon is on the next page.
Fig. 2-1. Map showing the route of the trip on Day 6. Initially, we will drive from
Furnace Creek Ranch to Darwin Canyon (STOP 2-1) where we will examine a
Permian sequence of deepwater deposits that includes turbidites and thick mass
transport units. In the afternoon, we will drive to Dolomite Fan (STOP 2-2)
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Road Log for Trip to Darwin Canyon
Distance (miles)
From Furnace Creek Ranch, we will turn left onto Hwy. 190 and follow it
through Stovepipe Wells, up the east side of the Panamint Mountains, across
Panamint Valley, and up the into the mountains on the other side.
Stovepipe Wells
25.9
Father Crowley Overlook (brief stop)
61.8
Turn off left to Darwin. The road log below starts at this point
72.4
Distance (miles)
1. Junction of Darwin road and Calif. Hwy. 190
2. City of Darwin. Turn right (left).
0
5.8
The road climbs the hill east of town then down the other side
and across some low flats.
3. Road drops off of flats and enters sand bed of creek
9.7
4. Old house
9.8
5. Gully to east exposes nice section of
thin- and thick-bedded turbidites, debris
flows, and contorted beds
10.3
6. 8-m-thick contorted layer within sequence of black,
fine-grained, finely laminated micritic units. Probably an
anoxic section. Note color change on cliff face to east
11.1
7. Sequence of thin-bedded turbidites
8. Road Junction. Turn right
11.4 -12.1
12.1
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9. STOP 6-1: Thin- to thick-bedded turbidites
and debris flow deposits in the Darwin
Canyon Fm. Note cyclic development
Of thick-bedded, coarse-grained gray
turbidites within section of thinner-bedded,
fine-grained, light-colored units
12.7
STOP 2-1
Darwin Canyon includes a thick sequence of Lower Permian rocks that
belong to the Darwin Canyon Formation (Stone and others, 1989) of the Owens
Valley Group. This formation is at least 1500 m thick in this area and composed
largely of deepwater detrital carbonate and mixed siliciclastic-carbonate
sediments. The Owens Valley Group lies above the sequence of Ordovician to
Mississippian carbonate-shelf deposits exposed in the southern Darwin Hills, so
a large amount of Late Mississippian to early Permian subsidence is implied. The
Owens Valley Group is overlain by Lower and Middle(?) Triassic rocks
deposited after uplift and partial erosion of the Permian rocks.
Where we will stop first, the Darwin Canyon Formation is made up
largely of sediment gravity flow deposits, including fine-grained sandy
turbidites and interlayered carbonate mudstones, some thick-bedded very
coarse-grained units that could be MTDs or the deposits of high-density
turbidity currents. These units contain shallow-water fossils. Thick MTDs (Fig. 22) contain a variety of eroded carbonate lithoclasts in a fine-grained muddy
matrix.
From STOP 2-1, we will retrace our route along the dry streambed,
stopping to examine the Darwin Canyon Formation. Based on the grain size,
sedimentation units, and stratigraphic architecture, we will discuss the
depositional settings represented by these rocks.
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Fig. 2-2. Turbidites of the Darwin Canyon Formation, STOP 2-1.
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Fig. 2-3. Carbonate debris-flow deposit in the Darwin Canyon Formation at
STOP 2-1 (from http://clasticdetritus.com/2009/09/).
Road Log for Trip to South Dolomite Fan
From the junction of the Darwin road and California Hwy. 190, we will turn left
and drive west on Hwy. 190 to the largely abandoned town and quarries at
Dolomite, then north along the Inyo Mountain front to the South Dolomite Fan.
Distance
(miles)
1. Junction of Darwin road and Calif. Hwy. 190
2. Low outcrops of Mesozoic plutonic rocks
0
0-1.6
3. Alluvial fan sediments
1.6-4.6
4. Pleistocene lacustrine sediment overlain
to north by Quaternary basalts
4.6-9.4
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5. Some very nice cuts in Quaternary basalts
and block and ash flow units
9.4-10.1
6. Calif. 190 turns left to Olancha. Continue
straight on Hwy. 136 toward Lone Pine
12.8
7. Alluvial fans along Inyo Mountains front are widely veneered
by aeolian sediments blown off of Owens Lake. There
has been a great deal of activity along the east side of Owens
Lake in recent years by the Los Angeles water district
in an effort to establish wet areas to inhibit entrainment
by the wind of lake-bed sediment, which contains toxic
evaporitic materials. When a similar trip was being scouted
in spring, 2000, strong winds entrained so much dust from
Owens Lake that it was impossible to see across the Owens
Valley from the Sierran front to the Inyo Mtns.
12.8-22.6
8. Turn off to right, Dolomite Loop Road. Turn right
22.6
9. Fork. Take right fork on Lone Pine–Owens Road
24.9
10. From this fork, we will drive about 3 miles to the north
along the Lone Pine-Owens road until a branch curves to
the right into a cove along the mountain front. We will
follow that road for about 1-2 miles to South Dolomite Fan.
29.5
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Fig. 2-4. Photo of the South Dolomite Fan area. We will enter the area from the
northwest, park for STOP 2-2 as indicated and traverse up the system, across the
modern lobe deposited during the 1984 debris flows, and up into the leveed
channel. The features produced by the 1984 debris flows have suffered
considerable degradation since they formed.
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STOP 2-2: South Dolomite Fan
On August 22, 1984, a series of coarse-grained debris flows was triggered
along the western front of the Inyo Mountains east of Lone Pine, California, by
precipitation from intense, localized thunderstorms. One debris flow originated
in the gully that feeds the South Dolomite fan, a small alluvial fan 0.5 km south
of the larger Dolomite fan (Fig. 2-4). The 610-meter-long deposit left by this
debris flow includes a single, nearly straight leveed channel on the steep (6˚-16˚)
alluvial fan (Fig. 2-6A) passing downward into a single unconfined debris lobe
on the lower fan and flat valley floor (Figs. 2-4, 2-5A, and 2-6C, D). Both the
levee and lobe deposits consist of poorly sorted, unstratified, clast-supported
pebble-to-boulder gravel, much with a sparse matrix of granules to very finegrained sand (Fig. 2-6B). The source area is composed exclusively of Paleozoic
carbonate and quartzitic rocks and, as a consequence, true clays are essentially
absent in these deposits. The absence of fine cohesive sediment means that flow
rheology was controlled entirely by frictional particle interactions. The flows
probably involved a series of steep-fronted gravel surges that were thickest and
coarsest at their snouts, waned rapidly, and were separated by intervals with
little or now gravel movement. A short distance north of South Dolomite Fan,
smaller gullies along the mountain front show similar "frozen" debris-flow
surges that ceased movement before reaching the valley floor (Fig. 2-5B).
Both levees and lobe exhibit well-developed inverse grading in debris
coarser than about 1.6 cm (Fig. 2-6B), reflecting dispersive pressure between
clasts during flowage resulting in an upward displacement of large particles
combined with kinetic sieving and downward movement of the smaller clasts.
The development of inverse grading requires that the flows were overall
laminar. However, the fine gravel, granule, and sand matrix within the pore
spaces between the coarser, inversely-graded levee gravel exhibits welldeveloped normal grading. This reflects the existence of turbulence within the
dilute water-sand matrix to the larger gravel along the margins of the flows. The
absence of grading in the lobe matrix is thought to reflect upslope deposition of
coarser debris, more uniform dispersion of finer debris by turbulence, and
abrupt sedimentation without the opportunity for differential particle settling.
Clasts within the levee and lobe show long axes oriented perpendicular to
the local flow direction. This is thought to reflect the final stages of movement
when deposits were shoved or pushed along by more mobile, rearward parts of
the flow and long clast axes were reoriented by jamming. The largest clasts in
the lobe, which exceed the thickness of the deposit, were unaffected by
dispersive pressure, rest against the surface over which the flow moved, and
show long axes perpendicular to flow direction. They were probably pushed
along by rolling and sliding.
33
We will park at the foot of the South Dolomite Fan (Fig. 2-4) and walk
upslope across the lobe and into the shallow leveed channel. If time allows, we
will walk as high as the beginning of the bedrock channel through which the
flows moved before passing onto the head of the alluvial fan.
34
Fig. 2-5. Debris-flow deposits along the western front of the Inyo Mountains east
of Lone Pine, CA. (A) Leveed channel and lobe of debris-slow deposits on South
Dolomite Fan, STOP 2-2. (B) Smaller "frozen" debris-flow surges in steep
mountain-front gully 0.5 km north of South Dolomite Fan. For scale, note person
near front of middle surge, upper left center of photograph.
Fig. 2-6. Dolomite Fan at STOP 2-2. (A) Leveed fan channel in the upper part of
the fan. The channel lobe transition with a few persons in the channel is seen at
the upper left edge of the photograph. (B) Inverse grading in the levee deposits.
(C) View downchannel of the transition from a leveed channel to the unconfined
lobe. (D) coarse cobble and boulder gravels on the lobe surface.
35
DAY 3: STUDENT TALKS
October 27, 2015
36
DAY 4: UBEHEBE MINE SECTION OF THE DEEPWATER
KEELER CANYON FORMATION
October 28, 2015
We will leave the front parking lot at Furnace Creek Ranch at 8:00 am,
prepared for a full day in the field. From Furnace Creek Ranch, we will drive
north on California Hwy. 190 for 17.5 miles to the junction with the road to the
right (north) to Scotty's Castle (Fig. 4-1).
Road Log for Trip to Ubehebe Mine
Distance (miles)
1. Furnace Creek Ranch parking lot. Go north on
California Hwy. 190
0
2. Junction with road to Scotty's castle. Turn right
(north) toward Scotty's Castle
17.5
3. Some of the low hills to the right (east) are made up
of older tertiary alluvial sediments
17.5-24.0
4. Very steep debris-flow dominated alluvial fan
along front of Grapevine Mountains to the east
29.3
5. Entrance Station
50.7
6. Left turn to Ubehebe Crater
50.9
7. Turn right to Racetrack. This is on the one-way
loop road around Ubehebe Crater.
Go straight; do not turn right
56.5
8. STOP 4-1: Ubehebe Crater overlook
57
9. Return to right turn to Racetrack. Turn right.
57.4
10. Front of Cottonwood Mountains to east shows
small, very steep, debris-flow dominated
alluvial fans
64.2
37
11. Teakettle Junction. Road to left goes to Hunter
Mountain. Go straight toward Racetrack
77.0
12. View on west face of last Chance Range ahead
shows Ordovician section of black Ely Springs
Dolomite underlain by orange-weathering
Middle Ordovician Eureka Quartzite underlain by Lower Ordovician carbonates.
77.7
12. Main road makes a sharp turn to the left.
Ubehebe Mine is straight ahead
79.1
13. Crest of hill
79.4
14. Ubehebe Mine – STOP 4-2
80.4
STOP 4-2: Ubehebe Mine and Keeler Canyon Formation
We will park at the Ubehebe Mine and hike down the dry gully to the
west for about 5 miles. Over about 4 miles of this distance, we will be hiking
through a thick section of lower to middle Paleozoic shelfal carbonates. The
Ubehebe Mine is within a fault zone that cuts outcrops of the Middle Ordovician
Eureka Quartzite. The Eureka Quartzite is overlain regionally by dark gray
dolomite of the Upper Ordovician Ely Springs Dolomite. As we hike down the
gully, we will pass through this unit and a great thickness of light colored,
poorly structured Hidden Valley Dolomite of Silurian and Early Devonian age.
This is overlain by dark to light shelfal dolomites of the Lost Burro Formation of
Middle to Late Devonian age. Overlying Mississippian units include the Perdido
Formation, a thick unit (>300 m) of thin-bedded, very fine-grained impure
limestone with interbedded chert and other siliceous beds. It marks a distinct
deepening of the conditions of deposition. This unit is overlain by the Rest
Spring Shale, a relatively thin (<100 m) unit of fine basinal shale associated with
a regional flooding event in the latest Mississippian and equivalent to the very
widely developed black organic-rich Devonian and early Mississippian shales
that cover much of the North American craton. It is succeeded by several
hundred meters of turbiditic and debris-flow strata of the Pennsylvanian Keeler
Canyon Formation. We will examine the Keeler Canyon Formation in a long
series of excellent stream cuts.
Miller and Heller (1994) describe the Keeler Canyon Formation:
Mixed carbonate-siliciclastic sediment gravity flow deposits of Late
38
Pennsylvanian to Early Permian age are exposed in the Death Valley - Owens
Valley region of east-central California. The Mexican Spring unit constitutes the
upper part of the Keeler Canyon Formation and is characterized by turbidites,
debris flow deposits and megabreccias, all of mixed carbonate-siliciclastic
composition. The mixed composition of the Keeler Canyon Formation provides
an opportunity to link facies architecture to controls on depositional system
development. Depositional relationships indicate that the deposits represent a
non-channellized base of slope carbonate apron system with inner, outer and
basinal facies associations. These gravity flow deposits are characterized by
repeated stacked, small scale (<15 m) coarsening and thickening upward cycles
with superimposed medium scale (> 100 m) coarsening and thickening upward
cycles.
The mixed clastic apron systems of the Keeler Canyon Formation differ
from classical carbonate aprons in that the former is characterized by an
abundance of sedimentary cycles. Controls on the development of these cycles
and of the facies distribution may have resulted from changes in type and rate of
sediment supply, relative sea level changes and/or tectonic events. Interpretation
of the data is focused on relative changes in sea level as the most significant
control on development of the depositional system. Relative sea level changes
serve two important functions: (1) they provide a mechanism for bringing coarse
siliciclastic and bioclastic grains together on the outer shelf, and (2) shelf margin
collapse may be initiated during relative lowstands allowing for transport of the
sediment to the deep basin and development of deep basinal cycles. Therefore,
an abundance of mixed clastic gravity flow deposits such as these in the
rock record may be an indicator of periods of high frequency changes in relative
sea level, which is a characteristic of Late Paleozoic sea level history.
References:
Miller, R.P., and Heller, P.L., 1994, Depositional framework and controls on
mixed carbonate-siliciclastic gravity flows: Pennsylvanian-Permian shelf to
basin transect, south-western Great Basin, USA: Sedimentology, v. 41, p. 120.
Yose, L.A., and Heller, P.L., 1989, Sea-level control of mixed-carbonatesiliciclastic, gravity-flow deposition: Lower part of the Keeler Canyon
Formation (Pennsylvanian), southeastern California: GSA Bulletin, v. 101, p.
427-439.
39
Fig. 4-1. Route of the field trip on Day 4 from Furnace Creek Ranch via Ubehebe
Crater to Ubehebe Mine and, in the afternoon, Racetrack Playa.
40
Fig. 4-2. STOP 4-1 - The Ubehebe Craters consist of an isolated group of
overlapping maars formed during eruptions of alkali basalt along a fault cutting
fanglomerate deposits. Ubehebe Crater is a 0.8-km-wide, 235-m-deep maar
surrounded by a tuff ring. Little Hebe Crater, the second youngest vent, is
located immediately south of Ubehebe Crater and is a small tuff cone with a 100m-wide crater overlain by pyroclastic-surge deposits. At least a dozen craters are
located within an area of 3 sq km, and bedded pyroclastic-surge deposits cover
an area of 15 sq km. Early scoria cone formation was followed by hydrovolcanic
explosions that formed two clusters of explosion craters and tuff rings. The age
of volcanism at Ubehebe is not dated precisely, but the lack of erosional
modification of pyroclastic-surge deposits suggests that the youngest activity,
from the largest crater, Ubehebe Crater, is Holocene in age. Relationships
between Ubehebe tephra and approximately dated archeological artifacts
41
suggests an age of about 6000 years (from:
http://www.volcano.si.edu/world/volcano.cfm?vnum=1203-16-).
42
Fig.4-3. Route for STOPS 4-2 and 4-3. We will park at the Ubehebe Mine, STOP
4-2, and hike along a route shown in Fig. 4-4. If time allows in the afternoon, we
will visit the famous sliding stones of Racetrack Playa at STOP 4-3.
43
Fig. 4-4. Map showing the general geology around the Ubehebe Mine and along
the route of the hike to examine deepwater deposits of the Pennsylvanian Keeler
Canyon Formation. This unit was deposited in deep water along the Paleozoic
continental margin of the North American Craton, perhaps in a foreland basin
setting (Fig. 1-7). It is composed of turbidites and debris-flow deposits composed
of mixed carbonate and siliciclastic sediments.
44
Road Log for Trip to Racetrack Playa
Distance (miles)
1. Ubehebe Mine: Reverse course from the way we came in
and drive back on gravel track to the junction with
the main road from Ubehebe Crater to Racetrack Playa
0
2. Junction with main road
1.3
3. Turn right (south) and follow the gravel road down the long
fan and along the west side of Racetrack Playa. Near the
south end of Racetrack Playa we will park (Fig. 4-3) for
STOP 4-3.
9.0
STOP 4-3. Racetrack Playa
The flat surface at the southern end of Racetrack Playa is famous for its sliding
stones. These are rocks from a few centimeters to tens of centimeters across that
have slid across the playa surface and left tracks in the soft mud. If the surface is
solid and dry, we will walk out to examine the stones. PLEASE DO NOT
TOUCH OR DISTURB THE ROCKS! These are being studied by a number of
investigators and should not be touched or moved.
The sliding stones have moved across the surface of the playa, leaving a
track as they go (Figs. 4-5 to 4-7). They have never been seen or filmed in motion.
Racetrack stones only move once every two or three years and most tracks last
for three or four years. Stones with rough bottoms leave straight striated tracks
while those with smooth bottoms wander. Stones sometimes turn over, exposing
another edge to the ground and leaving a different-sized track in the stone's
wake.
The sliding stones are most likely moved by strong winter winds,
reaching 90 mph, once it has rained enough to fill the playa with just enough
water to make the clay slippery. The prevailing southwest winds across
Racetrack playa blow to northeast. Most of the rock trails are parallel to this
direction, lending support to this hypothesis.
An alternate hypothesis builds upon the first. As rain water accumulates,
strong winds blow thin sheets of water quickly over the relatively flat surface of
the playa. A layer of ice forms on the surface as night temperatures fall below
freezing. Wind then drives these floating ice sheets, their aggregate inertia and
large area providing the necessary force required to move the larger stones. Rock
trails would again remain parallel to the southwest winds. According to
45
investigator Brian Dunning, "Solid ice, moving with the surface of the lake and
with the inertia of a whole surrounding ice sheet, would have no trouble pushing
a rock along the slick muddy floor."
A more recent theory is that ice collars form around rocks and when the
local water level rises, the rocks are buoyantly floated off the soft bed. The
minimal friction allows the rocks to be moved by relatively light winds.
Fig. 4-5 and Fig. 4.6. Sliding stones of Racetrack Playa
46
Fig. 4-7. A sliding stone that has taken a sharp right turn.
47
DAY 5: ALLUVIAL FANS
October 29, 2015
We will leave the front parking lot at Furnace Creek Ranch at 8:00 am, so
everyone should aim to arrive at about 7:45 am, checked out with luggage loaded
in your vehicles. From Furnace Creek Ranch, turn right (south) on California
Hwy. 190 for 1 mile to the junction with the road to the right (south) to Badwater
(map on next page).
Alluvial fans developed on the east side of Death Valley along the front of
the Funeral and Black Mountains are mostly relatively small, immature fans
because the main active fault of the Death Valley graben lies along this mountain
front (Fig. 5-1). These fans contrast with the enormous alluvial fans developed
along the Panamint Mountains on the west side of the Valley.
Blair and McPherson (1994) discuss some of the controlling variables on
the morphology and evolution of fans observed along this route. Three items are
very important: (1) The slope of the individual fans is directly related to the
processes that transport sediment across them. Talus cones are the steepest,
debris-flow dominated fans somewhat less steep, and streamflow dominated
fans the lowest gradient fans. (2) The various process-type fans also show
distinct differences in the grain-size of sediment at the fan surface, with talus
cones and debris-flow-dominated fans the coarsest and streamflow dominated
fans the finest. (3) The type of fan developed can be directly related to the source
sediments. For the first 15 miles south from Hwy. 190, we will traverse a series of
low- to medium-gradient, streamflow-dominated fans that drain parts of the
Black Range composed of older Tertiary, mostly Miocene and Oligocene alluvial
and lacustrine sediments. Southward from about 1.5 miles north of Badwater, the
road is located closer to the mountain front and along a series of small, steepgradient, debris-flow dominated fans that drain high-grade Precambrian igneous
and metamorphic rocks. These source-area contrasts translate directly into
differences in sediment supply (mainly grain size), processes of transport and
deposition, and slope and size of the alluvial fans. These same relationships are
relevant to source, sediment supply, processes, and geometry of deep-water fans.
In addition, the surface morphology of the modern alluvial fans in terms
of fan channel geometry and down-fan variability are similar to analogous
features on deep-water fans. One major difference is that deep-water fans are
typically much finer grained than most alluvial fans and differ accordingly.
48
Road Log: Furnace Creek Ranch to Badwater
Distance (miles)
1. Furnace Creek Ranch. Drive south on California Hwy. 190
0
2. Junction, California Hwy. 190 and road south to Badwater
For the next 15 miles, we will cross a series of small
to medium-sized, steamflow-dominated alluvial fans
1.0
3. Road to left (east) is exit for Artist Point Drive
5.8
4. Road to left across Death Valley to west side. Good view
ahead and to side of large streamflow-dominated fans
(Fig. 2-1). Fan drains area composed of Miocene
basalts and older Tertiary sediments
7.0
5. Entrance to left to Artist Drive
9.6
6. Crest of large streamflow-dominated fan composed
largely of small pebble and cobble-sized gravels
10.9
7. Crest of small, rather coarse medium-gradient fan.
13.4
8. Road to left goes to the natural bridge
14.0
9. Very steep, coarse, debris-flow-dominated fan
16.8
10. Badwater. Note steep talus cones and debris-flow-dominated
17.5
fans against mountain front. A small fan across from the north
end of the parking area is cut by recent fault. Gravels from older
fans that have been left stranded by downdropping of the valley
floor are preserved high on the steep mountain front.
South from Badwater are a series of classic, small, largely debris-flow
dominated alluvial fans (Fig. 5-2). An exception is the Copper Canyon fan, which
is a larger, lower-gradient, finer-grained fan fed by a stream draining an area of
Tertiary sediments in the Black Rock Range.
49
50
51
52
Alluvial Fans and Fan Deltas with Examples from the Warm Spring Canyon
and Anvil Spring Canyon Fans, Death Valley
Jonathan Rotzien
Introduction: In the hottest and driest conditions known to the United States lie
two adjacent alluvial fans: the waterlaid Anvil Spring Canyon Fan and the
debris-flow dominated Warm Spring Canyon Fan (Figs. 5-2 and 5-3). The Anvil
Fan was constructed entirely by water-flow processes, and the Warm Spring
Canyon Fan was built predominantly by debris-flow deposits. The Anvil Spring
Canyon Fan is composed of four facies, deposited by A) catastrophic flood events
and B) recessional flood events / non-catastrophic discharge (Figs. 5-4 & 5-5).
The Warm Springs is principally composed of clast-rich and matrix-supported
debris flow deposits 20-150 cm thick and has a completely different morphology
(Fig. 5-6).
The Anvil Spring Canyon Fan is located in the Panamint Range Piedmont
in the western-central portion of Death Valley, CA. 38 stations along a 7.1 km
long, 3-12-m deep incised channel were used to characterize the facies of the
radially-oriented fan. Bedrock catchment is composed of Miocene andesite (40%),
Mesozoic granite (23%), Triassic-Jurassic andesite (8%) and Precambrian marble,
dolomite and quartzite (3%): the remaining 26% is composed of alluvial
sedimentary cover. The bedrock catchment for the Warm Springs Canyon Fan is
Triassic-Jurassic and Miocene andesite (18% of catchment area), Mesozoic granite
(9%) and Precambrian-Palaeozoic dolomite, shale and quartzite (54%). The
remaining 19% is local alluvial cover.
Anvil Spring Canyon Fan: The Anvil Spring Canyon (ASC) Fan is dominated by
sheetflood processes of sedimentation (Figs. 5-3 thru 5-5). The ASC fan is 27 km2
in area, has a radial length of 9.7 km, and its apex is at 325 m above sea level with
its toe at 60 m above sea level. The West Side fault zone separates the proximal
and distal portions of the fan. It is sparsely covered by creosote, and rock varnish
studies show that abandoned fans have been inactive for 150,000-800,000 years.
The distal fan contains the ADL that has an expansion angle of 100° and an area
of 15.6 km2. Facies include A) horizontally-aligned, rhythmic gravelly and sandy
planar couplets, B) sandy gravel backset wedges, C) clast-supported, very poorly
sorted, pebble-cobble lenses and irregular beds and D) very poorly sorted and
weakly stratified, framework, imbricated, massively bedded cobble-boulder
gravel with boulder sizes 170 cm in diameter and are distributed systematically
about the fan (Fig. 5-4).
Facies A is composed of horizontally-aligned, rhythmic gravelly and sandy
planar couplets. Imbricated gravel bases are 5-25 cm thick, and sandy tops are 520 cm thick (Blair, 1999a). Coarse couplet beds are lenticular in shape and extend
53
for 1-5 m, and finer-grained beds for 1-10 m. Couplets originate from the violent
breaking of oversteepened standing waves that form in the deepest part of the
catastrophic flash flood (approximately 20% of the surface area of the
sheetflood). At this point called washout, a plane bed develops as the standing
waves are obliterated downfan by shooting flow (Fig. 5-7). Coarse gravels are
deposited as traction load at this time and are overlain by finer-grained
sediment, forming the couplets. Multicouplet stratigraphy is created by the fact
that the deepest part of the flow is ever changing across the surface of the fan,
thus forming interwoven packages of couplet bedding. Facies A is common in
the middle to distal portions of the fan (Figs. 5-4 & 5-5).
Facies B is less common than A and consists of sandy gravel backset wedges
(Blair, 1999a). Facies B is different from A in that it lacks coarse pebbles and is
composed of upfan-dipping cross-beds, backsets, that are lenticular wedgetrough to wedge-planar units about 10-60 cm thick. Maximum thickness of the
backset beds decreases from the apex from 45 to 25 cm. The lee margins of some
backsets shows downfan-dipping foresets, dipping 5-15°. Facies B is formed
from non-violent breaking of the standing wave during Froude supercritical flow
sheetfloods (Fig. 5-7). Facies B is present in the middle to upper portions of the
fan (Figs. 2-4 & 2-5).
Facies C is composed of clast-supported, very poorly sorted, pebble-cobble
lenses and irregular beds (Blair, 1999a). Bed bases are scoured, with scour axes
parallel to fan slope, and bedding is lenticular from a few cobbles to 10-100 cm
thick. Sand exists as an infiltrated matrix. Facies C is interpreted to form as
erosional lags and gully fills through secondary remoulding during recessional
flood stage. Facies C concentrates in the distal portions of the fan and form the
bounding sequences between 50-250 cm thick packages of Facies A & B couplet
and backset beds (Fig. 5-5).
Facies D is composed of very poorly sorted and weakly stratified, framework,
imbricated, massively-bedded cobble-boulder gravel with boulder clasts
reaching a mammoth 170 cm in diameter (Blair, 1999a). Typically single-bedded
(50-100 cm thick), it is limited in distribution. Long axes of boulders are oriented
perpendicular to flow direction. Facies D is present in the upper portions of the
fan and shows a laterally limited, ribbon-like geometry (Fig. 5-5).
Morphology & architecture interpretations: The Roaring River sheetflood
deposits of Colorado serve as an analog to the Anvil Spring Canyon Fan (Blair,
1999c). The high slope of the fan form prevails due to the decrease in flow depth
radially from the apex. The observation that the backsets typically occur higher
on the fan than the couplets supports this interpretation of lowering sheetflood
water depth from the apex. Facies A & B are formed during the catastrophic
discharge stage, and Facies C & D are formed during the recessional flood / noncatastrophic discharge stage. Reworking of the surface creates a “braidedstream” appearance, though this study questions the validity that 1) alluvial fans
54
are constructed by braided channel processes, 2) grain sizes systematically
decrease down fan, 3) waterlaid facies are deposited downfan of a debris-flow
tract (e.g. Trollheim Fan Model) (Blair, 1999a).
Warm Springs Fan: The Warm Spring Canyon Fan is 32.6 km^2 in area, has a
radial length of 8.1 km and a maximum width of 5.3 km. It is a debris-flow
dominated fan (Fig. 5-6). The incised channel is 5.5 km from apex to toe. Facies
include A) unsorted, bouldery and clast-rich, muddy, pebbly, cobble-gravel to
very coarse pebble gravel ranging from 20-150 cm thick and B) clast-supported,
very poorly sorted, bouldery, granule-pebble-cobble gravel to cobble-pebble
gravel with bed thicknesses ranging from 1-40 cm. These facies account for 90%
of exposures on the fan (Blair, 1999b). Incised channel deposits include Facies C
and D, which are composed of cobbly gravel and whitish-yellow mud,
respectively. Reworked lake deposits at the toe of the fan include Facies E, F and
G. The surface of the fan is notably steeper than that of the Anvil Spring Canyon
Fan (Blair, 1999c). For additional reading on alluvial fans, please refer to Blair &
McPherson (1994) and the references listed below.
References:
Blair, T. C. & McPherson, J. G., 1994. Alluvial fans and their natural distinction from rivers based
on morphology, hydraulic processes, sedimentary processes, and facies assemblages: J. Sed.
Research, v. A64, no. 3, p. 450-489.
Blair, T. C., 1999a. Sedimentary processes and facies of the waterlaid Anvil Spring Canyon
alluvial fan, Death Valley, California: Sedimentology, v. 46, p. 913-940.
Blair, T. C., 1999b. Sedimentology of the debris-flow-dominated Warm Spring Canyon alluvial
fan, Death Valley, California: Sedimentology, v. 46, p. 941-965.
Blair, T. C., 1999c. Cause of dominance by sheetflood vs. debris-flow processes of two adjoining
alluvial fans, Death Valley, California: Sedimentology, v. 46, p. 1015-1028.
55
Figure 5-3. Map of the Anvil Spring Canyon Fan
and the Warm Spring Canyon Fan (left) (Blair,
1999b).
Figure 5-4. Sheetflood
dominated alluvial fan morphology (above) (Blair & McPherson, 1994).
Figure 5-5.
Proximal
cross-section
of the Anvil
Spr. Cyn. Fan
(left)
(Blair, 1999c).
Figure 5-6. Debrisflow fan
architecture
(below) (Blair &
McPherson, 1994).
56
Figure 5-7. Flow reconstruction for the formation of the couplet facies in the
Anvil Spring Canyon Fan (Blair, 1999a).