Table Of ContentPetroleum Potential of the
Basin and Range Province
Central Nevada
July 3-7, t989
Field Trip Guidebook Tt t 3
Leaders:
Norman Foster, Louis Bortz, Herb Duey,
Alan Chamberlain and Steven Veal
American Geophysical Union, Washington, D.C.
Copyright 1989 American Geophysical Union
2000 Florida Ave., N.W., Washington, D.C. 20009
ISBN: 0-87590-664-8
Printed in the United States of America
COVER Trap Spring Oil Field, Grant Range in background. Photo by
Jack Rathbone.
Leaders:
Norman Foster
1625 Broadway, Ste. 530
Denver, CO 80202
Louis Bortz
1775 Sherman, Ste. 1345
Denver CO 80203
Herb Duey
Santa Fe Energy Co.
4900 California Ave.
Tower A, Ste. 400
Bakersfield, CA 93309
Alan Chamberlain
Cedar-Strat
P.O. Box 8909
Reno, NV 89507
Steven Veal
DCX Resources Ltd.
1776 Lincoln St., Ste. 1318
Denver, CO 80203
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IGC FIELD TRIP T113:
OIL AND GAS POTENTIAL OF THE BASIN AND RANGE PROVINCE
By Louis C. Bortz
Independent Petroleum Geologist, Denver, Colorado
INTRODUCTION
INDEX MAP
:--------------------~--------
The primary focus of this paper . .
will be in east-central Nevada where I NEVADA I: UTAH
the current economic fields are :
ELID
located. The Eagle Springs field in
Railroad Valley was discovered by I SALTLAKE
~
Shell oil in 1954. Since then the
I
search for additional fields has
been sporadic because of several
factors: relatively small
recoverable reserves, high
transportation costs, restricted
market and elusive traps. However,
three additional economic fields
have been found and some recent oil
discoveries could also be economic
fields. Mi
o 50 100
The Grant Canyon oil field t;....r-=-f ..- I
currently has the largest estimated o It 111
Km
recoverable reserves of 13 million
BO, however I believe that fields
with over 100 million BO will be
FIGURE 1 Index map showing major
found in this province. This is
tectonic features.
based on finding the proper
combination of areal extent,
reservoir quality and oil column in
one trap. over 80 miles to the east. This
thrust, originally dated as mid
Paleozoic, may be a Mesozoic-age
TECTONIC SUMMARY thrust (Ketner and Smith, 1982, and
Chamberlain, 1986). This thrust
Tectonically, this area is system extends in a broad N-S belt
between the Antler Orogenic Belt and across central Nevada including Pine
the Sevier Orogenic Belt (Figure 1). and Railroad valleys (Scott and
The Antler Orogenic Belt is Devonian Chamberlain, 1987). In some places
to Permian in age and the Sevier this thrust system has placed
Orogenic Belt is late Jurassic and Devonian reservoir rocks over
Cretaceous in age. The Roberts Mississippian source rocks. The
Mountain thrust in the Antler Sevier Orogenic Belt is part of the
Orogenic Belt area has carried Wyoming thrust belt and may extend
Ordovician to Devonian sediments from SE Wyoming to southern Nevada.
T113:
The Cordilleran geanticline
(Schuchert, 1923) between the Antler
STRATIGRAPHIC SUMMARY
and Sevier orogenic belts was first
uplifted during the Permian and
Phanerozoic rocks total over
persisted as a positive area until
50,000 feet (15,240 meters) in
late Cretaceous time. Some major
several areas in this province.
thrust faults are found in this
Good summaries of these rocks have
area. Mesozoic rocks are virtually
been prepared by several authors
absent in the area. During the late
(Stokes, 1979; stewart, 1980; and J.
Cretaceous and early Tertiary, local
A. Peterson, in preparation).
basins were formed by faulting and
In east-central Nevada, Cambrian
compressional folding (Stewart,
and Ordovician rocks are mostly
1980) and filled with fluvial and
marine carbonates with some
lacustrine sediments. The late
quartzites and shales. The Silurian
Eocene and Oligocene was a period of
is almost entirely dolomite with a
active igneous intrusions and
widespread ash flows. Extensional few shales. Devonian rocks,
tectonics were initiated during mid primarily marine limestones and
Miocene time to form the N-S dolomites, are an important oil
trending horsts and grabens of the reservoir. In some areas these
present Basin and Range Province. dolomites are reefoid deposits.
To date all of the oil fields Some clastics are found in the Upper
have been found within the grabens, Devonian and the pilot shale
but certainly traps could be present straddles the Devonian-Mississippian
in the horst areas. boundary.
The dramatic change to clastics
in Mississippian lithology is
probably a reflection of the Antler
Orogeny. Overlying the Devonian
Mississippian pilot shale and the
w
U shelf carbonates of the Joana
Z
< limestones, is a thick clastic
a:
Z wedge. The lower unit is the
QT ct
o Chainman shale which is one of the
W w
li major source rocks. The Diamond
Z
ct Peak clastics are interbedded with
cr
and overlie the Chainman shale.
These clastics range from sandstone
to coarse conglomerates and are an
important oil reservoir in the
Blackburn field in Pine Valley.
Pennsylvanian sediments in this area
AREA OF are primarily marine limestones with
SHEEP PASS BASIN minor amounts of fine clastics. The
QT
GEOLOGIC MAP r~ Permian is less widespread in
PAL o 6 12 Mi eastern Nevada and is composed of
o 10 20Km N both clastics and carbonates.
Mesozoic rocks are absent in much of
this area, probably because of
erosion during late Mesozoic time.
FIGURE 2 Generalized geologic map of In late Cretaceous to Eocene time
Sheep Pass basin, except for eastern there were several local basins
edge which extends for unknown where lacustrine and fluvial
distance in the subsurface east of sediments were deposited (Fouch et
map area. Mapped units shown are: aI, 1979). In the Railroad Valley
Paleozoics undifferentiated, PAL; area, lacustrine and fluvial
Cretaceous-Eocene Sheep Pass sediments of the Sheep Pass
Formation, TSPi Oligocene volcanic formation were deposited in the
rocks, Tov; Miocene to Recent Sheep Pass basin. Sheep Pass
volc~nic ~nd sedimentary rocks, QTi carbonates are productive in the
TertIary Intrusives, Ti. Eagle Springs field.
T113: 2
PANCAKE RAILROAD GRANT WHITE RIVER EGAN
RANGE VALLEY RANGE VALLEY RANGE
E
PRESENT-DAY STRUCTURE
W E
Tov
fi
;_pi__ (1 It rlp' t
PA_L PAL PAL
OLIGOCENE STRUCTURE
o 12
1L.-__--L..-__J
MILES
FIGURE 3 Sheep Pass Basin, west-east diagrammatic regional
structural sections. Lower section represents Sheep Pass
basin near end of Oligocene time. Upper section illustrates
present structure. Heavy fault lines represent beginning of
movement during Eocene time. Movement on lighter fault lines
began in late Oligocene or Miocene time. Solid bars show
producing formations in Eagle Springs field. Other symbols
same as Figure 2. Location of cross section shown on Figure
2.
FIGURE 4 Northern Basin and Range province. CJ - Major Neogene
and Quaternary basins; G1-Mostly pre-Neogene rocks; til -UPl?er
Tertiary volcanic rocks (6-17 m.y.); ~-Ea~t edge of BaSIn
and Range province; • -Oil field; .-Gas fIeld
T113: 3
Large portions of this area were several basins in east-central
blanketed by ignimbrites (ash flows) Nevada have source rocks at peak oil
during the Oligocene and these form generation.
oil reservoirs in the Eagle Springs
and Trap Spring fields. Late
STRUCTURE SUMMARY
Cretaceous to Oligocene intrusions
are common in east-central Nevada
A glance at the geologic map of
and three oil fields overlie or are
Nevada (Stewart and Carlson, 1978)
near intrusions.
shows the obvious north-south trend
of the present-day horsts and
SOURCE ROCK SUMMARY
grabens. Reduced to the simplest
There are four principal interpretation, the structure
formations in east-central Nevada beneath the valleys (grabens) and in
that are petroleum source rocks and the ranges (horsts) is essentially
have been described by Meissner et the same except the grabens are
al (1984) and Poole and Claypoole covered by up to 10,000 feet of
(1984). The Ordovician Vinnini and Miocene to Recent valley fill. In
the Devonian Woodruff formations are practice, the prediction of the
source rocks in the Roberts Mountain structure and subcrops beneath the
allochthon and could source traps valley fill remains quite difficult.
west of the leading edge of the Examination of the ranges shows that
Roberts Mountain thrust. The thick in some areas the structure and
Mississippian Chainman shales are outcrop pattern are quite simple and
source rocks over large areas in in other areas they are complex and
east-central Nevada and in my unpredictable because of several
opinion the major source rocks for periods of tectonic activity. The
this area. Late Cretaceous to simple case is illustrated by
Eocene lacustrine shales are locally Figures 2 and 3 in the Railroad
petroleum source rocks. Valley area. The Oligocene
Poole et al (1983) discuss structure sections show that
evidence for at least two episodes Oligocene volcanics overlie the
of petroleum generation in the Paleozoic in some areas conformably
northern Great Basin. They claim and in other areas (not shown)
that some of the source rocks were separated by an angular
at or near peak oil generation in unconformity. The faults in the
late Paleozoic time, but generation section show pre-Oligocene faulting
ceased when the rocks were uplifted that probably bounded the non-marine
and some were eroded during Mesozoic Eocene Sheep Pass basin. The
time. Generation probably resumed lighter fault lines on the Present
in adequately buried source rocks in day structure represent Basin and
the graben areas during late Miocene Range faults.
time.
Maturity values for these source
rocks are essentially the same in SURFACE AND SUBSURFACE HYDROCARBONS
the present ranges as those in the
grabens because of the relatively Bortz (1983) described the
small amount of time since the occurrence of subsurface (Figures 4
formation of the Basin and Range. and 5) and surface (Figure 6)
Thus, areas with favorable source hydrocarbons in the Northern Basin
rocks can be determined by source and Range. This report shows that
rock data from both surface and hydrocarbons are found in several
subsurface samples. Maturities areas, but are more abundant in
range from pre-generation to past those areas with mature source
peak, however source rocks in rocks.
T113: 4
FIGURE 5 Subsurface shows of hydrocarbons. , -Oil .and gas
P
shows; -Gas shows only.
FIGURE 6 Documented surface oil, gas and other hydrocarbon
occurences. aD -OiI seep; C -Gas seep; A -OiI stain or
droplets; <? -Asphaltite dike; 0 -Oil shale locality.
T113: 5
