BLM LIBRARY jHE MU$4t>E - f-iz DenrBof^7 A7 P'°'r CO 80S35-0047 FINAL REPORTD«*ver' 11X3 PHASE 1: GEM (GEOLOGICAL, ENERGY and MINERALS) RESOURCE ASSESSMENT FOR REGION 4, COLORADO PLATEAU THE PALISADE - GRANITE CREEK - SEWEMUP MESA AREA GRA 7 SUBMITTED TO: U.S. DEPARTMENT OF THE INTERIOR BUREAU OF LAND MANAGEMENT DENVER SERVICE CENTER DENVER, COLORADO 80225 MAY 1983 ditSh MSME/WALLABY ENTERPRISES "Sir A JOINT VENTURE OF MOUNTAIN STATES MINERAL ENTERPRISES, INC. and WALLABY ENTERPRISES, INC. TABLE OF CONTENTS SECTION II III IV VI PAGE FOREWORD 1 EXECUTIVE SUMMARY 11 INTRODUCTION 1-1 GEOLOGY II-l Physiography II-l Rock Units II-2 Structural Geology and Tectonics .... II-4 Paleontology II-7 Historical Geology II-8 ENERGY AND MINERAL RESOURCES II I- 1 Known Mineral Deposits III-l Known Prospects, Mineral Occurrences, and Mineralized Areas III-2 Mining Claims, Leases, and Material Sites . . III-4 Mineral Deposit Types III-4 Mineral Economics III-6 LAND CLASSIFICATION FOR GEM RESOURCES POTENTIAL . . IV-1 Leasable Resources IV-8 Locatable Resources IV-4 Salable Resources IV-12 RECOMMENDATIONS FOR ADDITIONAL WORK V-l REFERENCES AND SELECTED BIBLIOGRAPHY VI- 1 APPENDICES (SEPARATE ATTACHMENTS) FOREWORD This report is one of a series of eleven reports addressing the Wilderness Study Areas (WSA's) located in what has been designated as the Colorado Plateau, Region 4, by the Bureau of Land Management (BLM), Denver Federal Center. The study was under the direction of Mr. Robert J. Coker, the Contracting Officer's Authorized Representative (COAR). The WSA's have been segregated into eleven G-E-M (Geology, Energy, Minerals) Resources Areas (GRA's). Each designated GRA constitutes one report. The purpose of these reports is to assess the potential for geology, energy and mineral (GEA) resources existing within a WSA and GRA. This information will then be used by BLM geologists in completing the assessment for GEM resources potential within the WSA's, and for the integration with other resource data for the decision on suitability for recommendation of the respective WSA. The reports were developed and prepared by the Joint Venture team of MSME/Wallaby Enterprises, Tucson, Arizona, by Patricia J. Popp (Geologist), and Barbara J. Howie (Geologist) under the direction of Eric A. Nordhausen (Project Manager) and Richard Lundin (Principal Investigator), under BLM Contract No. YA-553-CT2-1041. Consulting support was provided by a highly specialized geological team composed of: Ted Eyde, Dr. Paul Gilmour, Dr. Robert Carpenter, Dr. Donald Gentry, Dr. Edger Heylmun, Dr. Larry Lepley, Annon Cook, Walter Heinrichs, Jr., and Charles Campbell. Their contribution is both acknowledged and appreciated. The work of Dr. Gilmour, Mr. Cook, Mr. Eyde, and Dr. Lepley should receive special acknowledgement. It was from the work of these consultants that this report on The Palisade-Granite Creek- Sewemup Mesa GRA was able to be completed. EXECUTIVE SUMMARY The BLM has adopted a two-phase procedure for the integration of geological, energy and minerals (GEM) resources data for suitable/nonsuitable decisions for wilderness study areas (WSA's). The two-phased approach permits termination of a GEM resour- ces data gathering effort at the end of Phase One. Phase Two is designed to gener- ate new data needed to support GEM resources recommendations. Over 10 million acres of WSA's require GEM resources data input. These WSA's are unequally distributed in the eleven western states of the coterminous United States. The WSA's are grouped in six large regional areas. The WSA's within the western part of Colorado, and a few crossing into Utah, were included as Region 4, also known as the Colorado Plateau Region. Except for one small area at the south- west extreme of the region and another at the north extreme, the region is within the northern half of the known Colorado Plateau physiographic province. The 32 WSA's within Region 4 encompass to 474,620 acres. These have been geogra- phically segregated within 11 designated GEM Resource Areas (GRA's). This report addresses the Palisade/Granite Creek-Sewemup Mesa Area, GRA 7. Within the GRA is included the Palisade WSA (CO-070-132) , Granite Creek WSA (CO-070-132A), and Sewemup Mesa WSA (C0-070-176, CO-030-310A) . The geology of the GRA consists mostly of sedimentary rocks. Uranium and vanadium minerals can occur as a secondary mineral in sedimentary rocks (notably certain sandstones). These are deposited from waters that have contacted primary uranium and vanadium minerals. The main mineral resources of the Palisade/Granite Creek-Sewemup Mesa GRA are uranium- vanadium. The Triassic Chinle and Jurassic Morrison and Entrada Formations are prevalent in the GRA, and occur in the Palisade/Granite Creek WSA's. These sedimentary forma- tions are all known producers of uranium and vanadium. The Palisade/Granite Creek WSA's contains uranium mines, workings, and occurrences. The Sewemup Mesa WSA contains no known mines or deposits. Few other mineralized areas were delineated in the WSA when investigated as part of the field examination and aerial photo interpretation functions. The classification for the leasable minerals, locatable and salable resources varies. An unknown potential for any leasable resources exists in the Palisade/ Granite Creek WSA's. However, moderate to high favorability exists in the Sewemup Mesa WSA in the form of oil and gas. There is high favorability in all WSA's for locatable minerals in the form of precious metals, base metals, and uranium and vanadium. There is also high favorability for salable resources in all WSA's in the form of dimension stone and clays. Overall, it is recommended that each WSA in the GRA receive additional work to determine the full economic potential of each area. This work should include fur- ther research in the unpublished and proprietary literature, a detailed program of geologic mapping and sampling, and additional geochemical and stratigraphic studies to confirm the occurrence or lack of geology, energy or mineralized commodities . ii SECTION I INTRODUCTION The Palisade/Granite Creek-Sewemup Mesa GEM (Geology-Energy-Minerals) Resource Area (GRA) located in southwestern Mesa and northwestern Montrose Counties, Colorado, and includes four Wilderness Study Areas (WSA's) (CO-070-132, CO-070-132A, CO-070-176, and CO-030-310A). The GRA area (Figure 1-1) is approximately 12 miles southwest of Grand Junction, Colorado. Located within the boundaries of the GRA is the small town of Gateway, Colorado, which is the local supply center for agricultural and ranching activities. Gateway is supplied by road from the regional supply center, Grand Junction, Colorado. The area includes all or portions of Townships 14 and 15 South, Ranges 101-105 West, and Townships 48-51 North, Ranges 17-20 West. The entire area is bounded by west longitudes 108° 56' to 109° 03' 29" and north latitudes 38° 25' 35" to 38° 54' 42". It contains approximately 643 square miles (1,731 square kilometers or 411,520 acres) of Federal, state, and private lands. The Bureau of Land Management portion of these holdings are under the jurisdiction of the Grand Junction and Montrose District Offices, and the Grand Junction and Uncompahgre Resource Area Offices. The specific WSA's within the GRA were chosen for study under this contract and have a total of 64,190 acres of federal land. The acreages of the various contained WSA's are listed below: Palisade (CO-070-132) 26,050 acres Granite Creek (CO-070-132A) 19,000 acres Sewemup Mesa (CO-070-176/CO-030-310A) 19,140 acres Because of their close proximity and generally same geologic structure, the Palisade and Granite Creek WSA's will be discussed as one WSA. They are located in the north central portion of the GRA, directly north and west of the town of Gateway and are bounded on the south by the Dolores River and West Creek. The Sewemup Mesa WSA is located in the southern portion of the GRA and is bounded on the east by the Dolores River. It is approximately 10 miles south of Gateway. Due to the lack of available data on each WSA, emphasis was placed on gaining an understanding of the mineral potential of each WSA within the GRA. Information on the mineral resources of the GRA was utilized to extrapolate and estimate the potentials of the contained WSA's from the existing data that in most cases, referred only indirectly to the WSA's. This is consistent with the purpose of this contract, which is to utilize the known geological information within each WSA and GRA to ascertain the GEM resource potential of the WSA's. The known areas of mineralization and claims have been plotted as overlays to Figure 1-1. 1-1 The information contained in this report was obtained from the published litera- ture, computerized data base sources, Bureau of Land Management File Data, and cer- tain company files. The information was compiled into a series of files on each WSA and a series of maps that cover the entire western portion of Colorado and eastern portion of Utah. After a thorough review of the existing data, a program of field checking was carried out by MSME/Wallaby's team of experts. Field inves- tigations in the area were carried out by Dr. P. Gilmour, Mr. Annan Cook, Mr. T. Eyde and personnel from the Grand Junctions District Bureau of Land Management Office. The field verification effort took place during the period of August 31 through September 2, 1982. Dr. Gilmour, Mr. Eyde and Mr. Cook are all registered professional geologists and associates of MSME/Wallaby. 1-2 MESA CO. 1 MESA CO. 5 lib 1° V lo X 1 < tttH « » < 1 ct '1 * »» H o Mm 6 w 3 < n UJ S -1 o • —————— JJESA_ C0_ 5_ MONTROSE CO. » — — — — (5 s so o E ■ z 5 z 47 tg X24.. OVERLAY D SAND. GRAVEL AND INDUSTRIAL MINERALS MESA CO. I mi-lo r MESA CO. 5 MONTROSE C6~l OVERLAY C COAL, OIL AND GAS MESA CO., I MESA CO 5 19 < M*B MB me Mm* UK Bmi m* 8 S8 9 3 • B BtM MB MX 1 III *»» i»B imB *** nff" H»« ~° «B mibHm te "•2 B'M 1MB MB _ J!£SA_ca_5 _ llONTROSE CO. I Hmm ™ PI MM IM1 **"m MMI Mil p/M .m mm MWgMll B,MI mi 13 3 <„i -tm .,"*'»JD»« ■sag "a b» ^k eg »r^::: p>- B Mil mm •ihBH"" MMHRffm OVERLAY B MINES, PROSPECTS AND MINERAL OCCURENCES C0-070-132A CO-070-132 030 310 A SI OVERLAY A PATENTED AND UNPATENTED CLAIMS AND WSA BOUNDARIES 104W 103W 102W I N 14S 15S 51N 50N 49N 48N 19W 18W 17W THE PALISADE/GRANITE CREEK/SEWEMUP MESA GRA SCALE 1:250,000 FIGURE 1-1 GEOLOGIC MAP EXPLANATION Quaternary Qae (Approximately Qa 2 million years Qap before present Qc (mybp) to present) Qct Qcl Qat Cretaceous Kmvg (Approximately Kmvu 135-62 mybp) Kc Kb Kmv Kmvr Kmb Km Kmu Kmfe Kml Kd Kbc Kdb Kmdb Jurassic Jm (Approximately Jmb 195-135 mybp) Jms Js Jem Je Jsem Jse Jwe Jurassic J Tr sen and Triassic J Tr n J Tr gc Triassic Trk (Approximately Trw 225-195 mybp) Trkw Trd Trwc Trc Trcu Trcb Alluvial and eolian deposits Alluvial deposits Pediment gravels Colluvial deposits Talus Landslide deposits Terrace gravels Mesaverde Group Upper part of Mesaverde Group Castlegate Sandstone Upper member of Blackhawk Formation Mesaverde Formation Mesaverde Formation, Rollins Sandstone Member Buck Tongue of the Mancos Shale Mancos Shale, undifferentiated Mancos Shale, upper shale Member Mancos Shale, Ferron Sandstone Member Mancos Shale, lower shale Member Dakota Sandstone Burro Canyon Formation Dakota Sandstone and Burro Canyon Formation Mancos Shale, Dakota Sandstone, and Burro Canyon Formation Morrison Formation Morrison Formation, Brushy Basin Shale Member Morrison Formation, Salt Wash Sandstone Member Summerville Formation Entrada Sandstone, Moab Sandstone Member Entrada Sandstone Summerville formation and Moab Sandstone Member of Entrada Sandstone Summerville Formation and Entrada Sandstone Wanakah Formation and Entrada Sandstone Summerville Formation, Entrada Sandstone, and Navajo Sandstone Navajo Sandstone Glen Canyon group - Navajo Sandstone, Kayenta Formation and Wingate Sandstone Kayenta Formation Wingate Sandstone Kayenta Formation and Wingate Sandstone Dolores Formation Wingate Sandstone and Chinle Formation Chinle Formation, undifferentiated Upper part of Chinle Formation Chinle Formation, Moss Back Member 1-3 Triassic continued Permian (Approximately 280-255 mybp) Trcm Trm Pe Pea Pew Pco Pec Pcwo Pcac Chinle and Moenkopi Formations Moenkopi Formation Cutler Formation, undifferentiated Cutler Formation, arkose and arkosic conglomerate Cutler Formation, White Rim Sandstone Member Cutler formation, Organ Rock Tongue Cutler Formation, Cedar Mesa Sandstone Member Cutler Formation, White Rim Sandstone Member and Organ Rock Tongue Cutler Formation, Transition zone, arkosic beds and Cedar Mesa Sandstone Member Permian & Pennsylvanian Pennsylvanian (Approximately 320-280 mybp) Precambrian (Approximately 3400-600 mybp) P Pr P Per Ph Phu Php PC Rico Formation Cutler and Rico Formations Hermosa formation, undifferentiated Upper Member of Hermosa Formation Paradox Member of Hermosa Formation Precambrian rocks, undifferentiated. 1-4 LEGEND CD -0 OIL FIELD ■ <;;;;;;;;: -g gas field n 1 □ C_3 -Os oil shale x ( ) -C COAL REGION >— # OIL WELL ^ -£ OIL a GAS WELL R •#- GAS WELL r # SHOW OF GAS 0 3 SHOW OF OIL /^s tif show of oil a gas ^ # -C COAL DEPOSIT .„ O -C COAL OCCURRENCE A SHUT-IN WELL X 0 C02 OR He=HELIUM -RICH WELL A DRY WELL-ABANDONED C^Z\ MILL n PLANT ° a NATURAL GAS PROCESSING (J PLANT 0 OIL Cb LIGNITE G GAS Cp PEAT Os OIL SHALE Ag SILVER Ot TAR SANDS Au GOLD Gi GILSONITE Cu COPPER C COAL CI CLAY 1-5 MINERAL OREBODY MINERAL DEPOSIT MINERAL OCCURRENCE PROSPECT ACCESSIBLE ADIT INACCESSIBLE ADIT VERTICAL SHAFT INCLINED SHAFT MINE TYPE UNKNOWN ACTIVE OPEN PIT, OR QUARRY INACTIVE OPEN PIT, OR QUARRY ACTIVE GRAVEL OR CLAY (CI) PIT INACTIVE GRAVEL OR CLAY (CI) PIT EXPLORATION HOLE WITH DATA AVAILABLE EXPLORATION HOLE WITHOUT DATA AVAILABLE UNPATENTED MINING CLAIM PATENTED MINING CLAIM MINERAL OR OIL a GAS LEASE Ds DIMENSION STONE Fc IRON Mn MANGANESE Pb LEAD U URANIUM V VANADIUM Zn ZINC SECTION II GEOLOGY PHYSIOGRAPHY The GRA boundary includes valley, high cliff and plateau areas along the course of the Dolores River and West Creek. The northern part of the area is characterized by canyons cutting the Grand Mesa-Pinon Mesa area. Vertical relief in this area is approximately 2,000 feet. This region is bordered on the southeast by Unaweep Canyon, and on the southwest by Lost Horse Basin and the upper drainage of Granite Creek. Unaweep Canyon lies along the course of West Creek and has steep rocky sides. Vertical relief in Unaweep Canyon varies between 1,500 feet and 2,500 feet. In the Lost Horse Basin area, the vertical relief is approximately 1,500 feet. Directly west of Unaweep Canyon and southeast of Lost Horse Basin is a prominent north-south ridge that divides the Dolores River and West Creek drainages. This ridge has very steep sides and is known as The Palisade. It forms an important feature of the Palisade WSA and has a vertical relief of 1,500 feet - 2,000 feet. To the west of The Palisade is a narrow valley along the course of the Dolores River. Vertical relief in this area is less than 500 feet. The area along the Dolores River, south of the town of Gateway is best described as a narrow canyon with deeply cut tributary canyons that isolate flat-topped mesas and ridges. Vertical relief along the course of the Dolores River in this area varies from 1,000 feet to 1,500 feet. The mesa tops and ridges on the eastern side of the Dolores River Canyon are fairly accessible and are the site of mining and ranching activities. These features (Blue Mesa, Flat Top Mesa, Outlaw Mesa, Potato Moun- tain, Bull Hill, Tenderfoot Mesa and Juanita Arch) have a vertical relief of 1,500 to 2,000 feet. On the western side of the Dolores River drainages are other, more isolated, mesa and ridge features (Sewemup Mesa, Martin Mesa and Dolores Point), that are bounded by canyons having a vertical relief of 1,500 to 2,500 feet. To the west and south of the flat- topped mesa-ridge area are a series of valleys (Sinbad and Paradox Valleys) that trend northwest and are bounded on the southwest by steep-sided ridges and mesas. The valleys are of low, internal relief (less than 500 feet), and are bounded by ridge and mesa features that rise approximately 2,000 feet from the valley floor. The following descriptions address the physiographic composition of each of the in- dividual WSA's within the Palisade/Granite Creek-Sewemup Mesa GRA. PALISADE /GRANITE CREEK WSA (CO-070-132/132A) Within the boundary of the WSA are areas of steep topography that have been sculp- tured by fluvial and tectonic processes. The most striking feature of this type is the steep-walled erosion remnant known as The Palisade. Here, erosion has left a prominent ridge of Permian through Jurassic rocks that rises up 2,000 feet from the West Creek drainage. To the west of The Palisade and within the Granite Creek portion of the WSA is Lost Horse Basin, which is characterized by low rolling topo- graphy cut by the 900 feet deep Granite Creek Canyon drainage. The WSA includes portions of the Dolores River drainage and its valley system that extends north from Gateway. In the eastern and northern portions of the WSA are areas where the Paleozoic and Mesozoic rocks form steep cliffs that are capped by mesa tops. Vertical relief from the bottom of Unaweep where the basement Precambrian section is exposed, to the mesa tops is approximately 2,500 feet. II-l SEWEMUP MESA WSA (CO-070-176 and CO-030-310A) The gently sloping topography of the top of Sewemup Mesa Is the most striking physiographic feature of this WSA. The northern boundary of the unit is the steep southern wall of Salt Creek Canyon. The eastern boundary follows the line of cliffs that forms the western wall of Dolores River Canyon. These cliff features tend to isolate the Sewemup Mesa top from human activity. The mesa top rises near- ly 1,500 feet from the floor of Sinbad Valley and consists of resistent Triassic and Jurassic sediments. In addition, the mesa top is highly dissected by numerous shallow canyon systems that have a general west-east drainage. In the southern and western portions of the WSA are areas of low to moderate relief that are a part of the Sinbad Valley. On the Dolores River Canyon side of the WSA, and along Salt Creek Canyon, the Triassic Chinle Formation is exposed and forms the canyon bottoms. In these areas, the vertical relief is 500 to 700 feet. ROCK UNITS Within the Palisade/Granite Creek-Sewemup Mesa GRA is found a variety of rock units representing a large part of Precambrian, Paleozoic, Mesozoic and Quaternary time. The Precambrian section is represented by a complex of quartz-biotite and quartz-feldspar gneisses and schists that have been intruded by younger Precambrian felsic and mafic bodies (pegmatities-aplites-lamprophyres) . These gneisses and schists have been moderately deformed. The Precambrian sequence is relatively unstudied in this area and has not been extensively dated or correlated to other sections of Colorado. The exposures of these units are found in the northern and central parts of the GRA. The best exposed section of Precambrian Rocks is found in Unaweep Canyon and west of Pinon Mesa (Williams, 1964). In the Sinbad Valley area, the Paleozoic section has been brought to the surface by tectonic and salt dome activity. The Pennsylvanian Hermosa and Rico Formations are exposed and consist of fossiliferous marine limestone, siltstone, sandstone, arkose and conglomerate units. This portion of the sequence is thought to represent a period of rapidly fluctuating marine and terrestrial deposition. The basal portion of the Hermosa Formation is the well-known Paradox Member, which is thought to be part of a salt dome system. This unit consists of a thick section of alternating gypsum, salt, anhydrite and marine limestone units with occasional units of gray sandstone and black shale (Williams, 1964). This unit has associated oil and gas deposits, and is a potential source of brines, sulfur, gypsum, salt and anhydrite. In other areas of the GRA, the Paleozoic section consists of fluvial arkoses and conglomerates of the Permian Cutler Formation. This unit is thought to represent a period of fluvial deposition in shallow basins adjacent to the eroding Precambrian highlands (Carter et al, 1965; and Williams, 1964). The overlying Mesozoic section consists of Triassic mudstones, sandstones, silt- stones and conglomerates of the Chinle, Wingate, and Kayenta Formations. These units are thought to be of terrestrial origin and were probably deposited in a fluvial or eolian environment adjacent to a series of shallow inland lacustrine basins. Thin limestone units in the Kayenta Formation are thought to represent periods of fresh water lacustrine deposition (Carter et al, 1965; and Williams, 1964). Directly underlying this sequence and conformably overlying the Paleozoic stratigraphy is the Triassic Moenkopi Formation. This unit is separated from the rest of the Triassic stratigraphy by a regional unconformity. It consists of II-2 sandstone and mudstone members with local beds of arkoslc conglomerate and gypsum (Carter et al 1965; and Williams, 1964). The Moenkopi appears to have been deposited in a shallow water fluvial or lacustrine setting that was subjected to periodic dessication. The overlying Moss Back Member of the Chinle Formation is known to contain abundant plant remains in other parts of Colorado and Utah, and is the uranium-vanadium bearing host rock in the Lisbon Valley area of eastern Utah. An equivalent to this unit may exist in the GRA, and thus have potential for uranium-vanadium deposits (Carter et al, 1965; and Williams, 1964). Directly overlying the Triassic sequence and sometimes mapped with it, is the Navajo Sandstone. This Triassic- Jurassic eolian terrestrial sandstone is found in only a few areas in the southern part of the GRA and is thought to represent a period of inland sand dune deposition or a desert environment (Carter et al, 1965). The Jurassic sequence begins with Entrada Sandstone and the Summerville Formation. These units are thought to represent a period of terrestrial fluvial and eolian deposition in small, restricted basins (Carter et al, 1965). They outcrop throughout the GRA and have been known to contain tabular uranium/ vanadium deposits in the Slick Rock area (Williams, 1964). The Morrison Formation completes the upper Jurassic sequence of terrestrial fluvial and lacustrine sediments. This unit is well known for its uranium/ vanadium depos- its in other areas of Colorado. This unit and especially its Brushy Basin Member, is known to contain numerous uranium/vanadium beds within the GRA. The fluvial and lacustrine shale, mudstone, sandstone, and limestone units of the Morrison Forma- tion are thought to have been deposited in fluvial environments adjacent to shal- low, fresh-water lakes in shallow, inland, terrestrial basins (Carter et al, 1965). The major uranium/vanadium deposits of the region have been found in the sandstones units of the Salt Wash Sandstone Member. This unit outcrops throughout the central, southern and northern portions of the GRA and has major potential for "roll-front" sandstone hosted uranium- vanadium mineralization. ("Roll-front" mineralization occurs as elongate concretionary structures encompassed by vein-like concentrations of uranium-vanadium-bearing clay minerals.) The upper member (Brushy Basin Shale Member) of the Morrison is also known to contain uranium/ vana- dium deposits. This unit contains beds of bentonitic mudstone, fluvial sandstone and conglomerate lenses. The uranium-vanadium mineralization of the Brushy Basin Shale Member appears to be confined to the fluvial environment, with the best concentrations of mineralization being found in conglomerate lenses in association with organic "trash". Some of this "trash" is fossil plant and saurian material (Carter et al, 1965; and Williams, 1964), and, thus, has been recognized as a paleontological resource for Jurassic vertebrates. The Lower Cretaceous section is represented in the GRA by the Burro Canyon Formation. This unit consists of a series of mudstone, siltstone, shale and mudstone beds that are interbedded with fluvial sandstone and conglomerate units, and a few, thin beds of impure limestone (Williams, 1964). The fluvial character of these clastic units suggests that the environment of deposition was one of sedimentation along meandering river systems with adjacent, shallow terrestrial lakes. The area may have also been undergoing uplift during this period, as there is an unconformity at the top of Burro Canyon Formation. This unit consists of quartzitic sandstone, conglomeratic sandstone, carbonaceous non-marine shale and a coarse, basal conglomerate (Williams, 1964). The shale units are well known for fossil remains, and locally contain thin seams of coal (Gentry, Personal Communication, 1982). This unit has some potential as a source of coal, but outcrops in only a few areas within the GRA. It is mainly found on mesa tops in the central and western portion of the GRA. II-3 The rest of the Mesozoic and all of the Cenezoic section do not outcrop within the GRA. It is thought that these units were not deposited within area or were eroded in the Tertiary. Unconformably overlying the exposed Precambrian, Paleozoic and Mesozoic stratigra- phy is a series of Quaternary fluvial, eolian, colluvlal and alluvial deposits that represent periods of recent erosion and fluvial deposition. The following descriptions address the rock units of each of the individual WSA's within the Palisade/Granite Creek-Sewemup Mesa GRA. PALISADE /GRANITE CREEK WSA (CO-070-132/132A) Within the boundaries of the WSA are found the following rock units: Precambrian gneisses and schists that have been intruded by younger Precambrian felsic and mafic bodies (pegmatites-aplite-lamprophyres) ; the Permian Culter Formation, the Triassic Moenkopi, Chinle, Wingate and Kayenta Formations; the Jurassic Entrada, Summerville and Morrison Formations; and Quaternary alluvial and eolian deposits. Uranium-vanadium mineralization was found within the WSA in the Morrison Formation outcrop on the top of The Palisade ridge. Copper-silver mineralization has been found in the Triassic Chinle and Wingate Formations in other areas of the GRA, and east of the WSA in Unaweep Canyon. The quarternary gravel deposits adjacent to the WSA in West Creek Canyon and Unaweep Canyon have been a past source of sand, gravel and placer gold (Williams, 1964). SEWEMUP MESA WSA (CO-070-176, CO-030-310A) Within this area, only the Mesozoic section outcrops. The Triassic Chinle, Wingate and Kayenta Formations form the steep-walled sides of Sewemup Mesa. The Jurassic section caps the mesa top and consists of the basal Navajo Sandstone and the Entra- da-Summerville section. A few isolated outcrops of the Morrison Formation are found on peaks in the highest portions of the WSA. The copper-silver mineraliza- tion in the Triassic section is well known and extends into the WSA (Gilmour, field notes and summaries; 1982), and remains as a mineral resource with signifi- cant economic potential. Sections of the Paleozoic stratigraphy in the adjacent Sinbad Valley area are known to contain oil, gas, sulphur, salt, gypsum, barite, anhydrite, and brine resources. This stratigraphy is though to underlie much of the WSA (Shoemaker, 1956), and represents a significant mineral resource potential. STRUCTURAL GEOLOGY AND TECTONICS Structural features within the GRA include high angle faults that strike northwest and west-northwest, northeast striking faults and shear zones, and some local fold structures that are a part of the Sinbad Valley salt dome system. The northwest striking faults found in the northern and central portions of the GRA form a series of horst and grabens that parallel the trace of the Uncompahgre plate. The horst and graben features (Ute Creek Grabben, Unaweep Canyon Horst, Sandflat Grabben) have exposed thick sections of the Precambrian basement, and downfaulted blocks of the overlying Mesozoic section (Williams, 1964). Movement along these northwest striking faults and associated shear systems has formed a series of northwest striking ridges and valleys that are generally parallel to the fault systems and the axis of the Uncompahgre Plateau. Jointing in these areas is generally parallel to the northwest structural fabric. The northwest strike of the Dolores River II-4 Canyon south of Gateway probably is a result of these northwest striking ridges and valleys. The west-northwest faults and shear systems that are found in the northwest portion of the GRA appear to cut across the northwest structural fabric, and may not be a part of the Uncompahgre structural system. These faults and parallel shear systems (Ryan Creek and Dry Gulch Fault Zones) have also exposed the Precambrian section in the area north of Lost Horse Basin. Throughout the GRA, northeast striking faults and joint systems are responsible for the sculpting of the northeast striking ridges and canyons that are perpendicular to the trace of the Uncompahgre Plate and the dominant northwest structural fabric. These structures (West Creek Canyon, Salt Creek Canyon, and Granite Creek Canyon) have cut the major northwest trending ranges into a series of isolated mesas and ridges and may have played an important part in localizing copper-silver deposits in the Triassic units, since the fractures may act as pathways for solutions to migrate, and locations for copper mineralization to be deposited (Fisher, 1936). In a similiar vein, uranium- vanadium deposits in the Jurassic Morrison may have been localized by fractures acting as pathways for hydrothermal solutions which may have precipitated uranium or vanadium (Shoemaker, 1956). Several fold and basin structures are known to exist in the southwest portion of the GRA and are thought to be associated with salt dome formations in the Sinbad Valley area. A number of these anticlinal and domal structures were formed by salt dome growth and are especially important in localizing, in structural traps, oil and gas deposits. Along the margins of these fold structures are a series of northwest striking normal faults that also have associated oil and gas deposits. These faults parallel the regional northwest structures that bound the Paradox, Sinbad, Castle, and Lisbon Valley Basins, and are thought to be related to a major plate boundary. The stratigraphy of the southwestern portion of the GRA has been extensively stud- ied by major oil companies and the Federal government. In addition, the stratigra- phy of the central and southern portions of the GRA has also been thoroughly inves- tigated due to the uranium-vanadium potential of Mesozolc rocks in the area. Other parts of the GRA have been mapped by the United States Geologic Survey and various students. From the work that has been done, it appears that there is a major unconformity at the base of the Permian, and that the entire Paleozoic pre-dating the Permian section is missing. This unconformity may represent a period of uplift and erosion of the Paleozoic and Precambrian sections in a cratonic environment . Another unconformity is found at base of the Triassic Chinle Formation, and probably represents a period of erosion and non-deposition caused by uplift along the periphery of the Uncompahgre Highland. In the Unaweep Canyon area, the Permian Cutler Formation rests directly on the Precambrian complex. In the Sinbad Valley area, the Cutler Formation is exposed only in a few outcrops and appears to rest directly on the Pennsylvanian section. It thus appears that the Cutler represents a sequence of clastic sediments that were being deposited adjacent to a tectonically active highland subsequent to the filling of great off-shore marine basins. Thus, the unconformity at the base of the Cutler may be a time transgressive feature from area to area in the GRA. The following descriptions address the structural and tectonic characteristics of each of the Individual WSA's within the Palisade/Granite Creek-Sewemup Mesa GRA. II-5 THE PALISADE /GRANITE CREEK WSA (CO-070-132/132A) Structural features within the Palisade/Granite Creek WSA include northwest strik- ing high angle faults that parallel the trace of the Uncompahgre Plate. These faults have exposed the Precambrian section and have preserved several down-dropped blocks of Mesozoic rocks. As mentioned in the previous section, joints parallel to these faults have localized uranium-vanadium mineralization in the Jurassic Morrison Formation and may have aided in the localization of copper-silver mineralization in the Triassic section. Within the WSA are several northwest striking canyons and ridges that are essentially parallel to this dominant structural trend. Displacement along some of these structures is in the order of 1,000 feet. Northeast and west-northwest striking fault and joint systems are also found within the boundaries of the WSA. Again, these may have had an important role in localiz- ing uranium mineralization in areas of the GRA southeast of Gateway and along the Dolores River Valley. These fault and joint systems were responsible for the cur- rent course of the West Creek along the eastern boundary of the WSA. Granite Creek is located along one of these northeast striking fault systems. Also in the Granite Creek portion of the WSA are a series of west-northwest canyons that paral- lel the Ryan Creek Fault Zone. Major unconformities identified in the WSA include the major, time-transgressive unconformity at the base of the Permian section and the regional unconformity between the Moenkopi and Chinle Formations at the base of the Triassic section. SEWEMUP MESA WSA (CO-070-176 & CO-030-310A) This unit is bordered by northwest and northeast striking fault and shear zones that have deeply cut the canyons defining this unit. On the northern boundary of the WSA is a series of northeast striking normal faults that have concentrated cop- per-silver mineralization at the Copper Rivet, and other past producing properties. This area is a part of a major regional structural northeast horst and graben fea- ture, the Salt Creek Graben, that was probably formed due to extension along the predominant northwest Uncompahgre Plate and associated paralleling fault systems. Numerous parallel joints and fractures in this area have served as conduits for transported copper mineralization that was originally deposited within the Triassic units. Along the western boundary of the WSA are found a series of parallel, high angle reverse and normal faults which form the boundary of the Sinbad Valley Basin. Dis- placement on these fault sets is in the order of 1,000 feet to 2,000 feet (Shoemaker, 1952). Oil and gas deposits have been localized along these faults that form excellent structural traps. In the southern portion of the WSA, the fault and jointing pattern is not known. From the work of Dr. L. Lepley, it appears that the dominant structural system is a series of west-northwest and east-northeast striking structures that may be responsible for controlling the uranium-vanadium mineralization at the Rajah Mine area. Circular structures were identified on the photos of the area and may be surficial expressions of underlying basin or salt dome features (Lepley, 1982 Personal Communication). All of these features could also have some importance in the localization of any copper-silver mineralization in the Triassic section. II-6 Within the boundaries of the WSA, the Precambrian basement complex is thought to exist at some considerable depth (greater than 5,000 feet), and is thought to be unconformably overlain by sections of the Paleozoic stratigraphy. The exact nature of the unconformity is unknown in this area (Shoemaker, 1952). PALEONTOLOGY The paleontological occurrences of the GRA have been studied in some detail in conjunction with oil, gas, uranium, and vanadium exploration activities and govern- ment programs. Considerable information has been gathered on the paleontological occurrences of the Jurassic formations (Carter et al, 1965). From the literature it is known that the Pennsylvanian Hermosa and Rico Formations contain fossiliferous limestone units (Carter et al, 1965). The Triassic Chinle Formation is also known to contain reptile, amphibian and plant remains in other areas of Colorado. The most significant potential host rock sequence for paleontological remains, however, must be the Jurassic Morrison Formation, which is well known for its saurian reptile, bird, and mammal fossils. The published literature directly pertaining to the GRA generally describes the saurian remains in the Brushy Basin member of the Morrison Formation (Shoemaker, 1956; Carter et al, 1965; NPS File Data), but does not describe any fossil localities of major significance. The Cretaceous Dakota Formation is known to contain fossil plant remains and coal seams, but these units are not known to contain any fossil localities of major significance (NPS File Data). The following descriptions address the paleontological occurrences of each of the individual WSA's within the Palisade/Granite Creek-Sewemup Mesa GRA. THE PALISADE /GRANITE CREEK WSA (CO-070-132/132A) The Triassic, Jurassic and Cretaceous units outcropping within the WSA are known to contain fossil plant and reptile remains, but are not known to contain any fossil localities of major significance. Potential paleontological occurrences include reptile, amphibian and petrified wood material from the Triassic Chinle Formation; bird and small mammal remains from some of the upper members of the Morrison; and fossil plant remains from the Cretaceous Dakota Formation. The only reported occurrence of fossil material within the WSA is from a uranium-vanadium prospect on the top of The Palisade ridge. At this locality, the field investigators noticed there was organic material associated with the mineralization, which may have been the remains of logs that were preserved in stream channels in the Morrison. The lack of environments conducive to preservation of fossil material and the lack of outcrops of units with known, fossil resources combine to give this area a general- ly lower relative potential for paleontological occurrences. SEWEMUP MESA WSA (CO-070-176, CO-030-310A) In this area, the paleontologic occurrences are restricted to the Triassic Moenkopi, Chinle, Wingate, and Kayenta Formations. Underlying much of the WSA is the fossiliferous Pennsylvanian and Permian section. These units have little in the way of potential for paleontological occurrences but have been well studied by various oil and gas companies, and the Federal government. The Triassic section, II-7 exposed in the WSA, is not known to contain any fossil localities of major significance, but has not been extensively studied. The Triassic Chinle Formation is known from the literature to contain reptile, amphibian, and plant remains in other areas of Colorado. Scattered outcrops of the Jurassic Entrada, Summerville and Morrison Formations outcrop on the mesa tops within the WSA. These units are known to contain reptile, bird and mammal remains in other areas of Colorado. No reported occurrences of fossil material are known from these units within the study area (NPS File Data). HISTORICAL GEOLOGY During middle Precambrian time the entire GRA was receiving sediments from both cratonic and island arc sources (Gilmour, Personal Communication, 1982). It appears that this was a time of persistent volcanism and tectonic activity. Marine deposition of eugeosynclinal sediments was interrupted by the ebb and flow of cratonic and island-arc volcanism, and a period of extreme deformation was caused by plate collisions and regional uplifting. These older Precambrian units were metamorphased, deformed, and intruded by a series of younger Precambrian mafic and felsic bodies. In this study area, the exposed older Precambrian rocks are mainly intrusive masses of granite that have partially absorbed the earlier gneiss and schist material. Some of these intrusives contained anomalous amounts of metals, and have mineral deposits associated with them in other parts of Colorado and western United States (Vanderwilt, 1947). Other base and precious metal deposit types are commonly found in Precambrian lithologies. These exahalative deposits, found in association with marine basins and rhyolitic volcanic systems, are commonly associated with the older Precambrian lithologies. Younger Precambrian or Paleozoic intrusives have intruded the older, highly metamorphased and deformed complex of granite, gneiss, schist, pegmatite, aplite and lamprophyre lithologies. This later granitic unit appears to have altered the units it intruded, and may be partially responsible for vein deposits of base and precious metals, beryl, and fluorspar that are found in adjacent areas to the east of the GRA. The Precambrian sequence is relatively unstudied in this area and has only been partially correlated with other areas of Colorado (Cater, 1955). In parts of western Colorado, the younger Precambrian is partially preserved, and consists of a thick section of clastic sediments. These lithologies represent a period of clastic deposition in a marine environment. The only area within the boundaries of the GRA where such an environment may have existed is along southern and western boundaries of the GRA, west of the Uncorapahgre Uplift (a highland area in western Colorado that rises 3,000 to 5,000 feet higher than the surrounding terrain). From the seismic and drilling information that is currently available, it appears that the younger Precambrian units of this area were deposited in a deep, marine basin that persisted through Paleozoic time (Baars et al, 1981). Approximately 1,700 million years before present during the Precambrian, there was a period of uplift and rift formation that set the stage for all subsequent events in southwestern Colorado (Baars et al, 1981). These events which caused the formation of a large and deep rift basin adjacent to the Uncompahgre Uplift, and II-8 was caused by deep north-south compress ional crustal forces (Baars et al, 1981). With the formation of this deep basin, all sedimentation was restricted to the basinal area, and the deformed and intruded Precambrian basement complex was sub- jected to erosion. Within the GRA, it is thought that this deposition continued through Permian time. Though the only Paleozoic rocks that outcrop in the GRA are the Pennsylvanian and Permian lithologies, it is very probable that the full Paleo- zoic section exists in the extreme southwestern portion of the GRA (Baars et al, 1978; Shoemaker, 1952). This period of early and middle Paleozoic deposition was characterized by the for- mation of a series of shallow basins along the deep rift valley. It is thought that these basins were progressively filled by Cambrian, Devonian, and Mississippi- an sediments (Baars et al, 1981). These units were then downfaulted into the rift zone during periods of tectonic activity. These periods of vertical movement were precursors to the extreme orogenic episodes that occurred in the beginning of Middle Pennsylvanian time, when Precambrian units were uplifted rapidly and formed highlands that shedded between 15,000 and 20,000 feet of clastic sediments (Baars et al, 1981). These sediments filled the deeper parts of the adjacent structural trough. This highland continued to exist throughout Pennsylvanian and Permian time, and was partially inundated by the clastic sequences of the Permian Cutler Formation. During most of the Paleozoic, the deep rift basins teemed with plant and animal life. Reef communities were formed on shallow marine bedrock highs or to form with algal bloherms. Northwest striking faults and shear systems were active within the basins, and caused much in the way of up and down movement of the base- ment blocks that formed the floor of these basins. Certain basins along the rift zone were isolated by tectonic activity and became stagnant, inland, lacustrine bodies that were so filled with terrestrial sediments that they were unable to support life and became depositories of thick marine evaporite sequences (Barrs et al, 1981). As a result of the formations of the evaporites, salt domes, anti- clines, and diapirs formed with succeeding tectonic movements. These structural features were caused when the plastic evaporitic lithologies began to flow in response to tectonic stresses. The result of this movement was to form structures that displaced up to 14,000 feet of strata and created a series of diapirs and tight folds (Shoemaker, 1952, Baars et al, 1981). Faults that formed along the margins and axial planes of these flowage features were active in Pennsylvanian and Permian time, and added to the structural complexity of the pre-existing basins. In the Mesozoic, the area was the site of fluvial and lacustrine deposition in a terrestrial environment. The Triassic Moenkopi Formation overlies the Paleozoic units In much of the GRA, and is thought to represent an era when shallow, fresh water lakes in enclosed basins were subjected to periods of dessication and shallow water, clastic deposition. The Moenkopi Formation is known for' its saurian tracks and vertebrate fossils in other areas of western Colorado. Thus, it is reasonable to assume that amphibian and reptile life may have existed within the GRA during this period (NPS File Data). The Chinle, Wingate, and Kayenta Formations of the Glen Canyon Group represent a time of Triassic sedimentation in a near-shore environment with episodes of eolian deposition of well cross-bedded beach and dune sand deposits. Certain fluvial and shallow water lacustrine deposits have also been identified in this sequence of sandstone, shale, siltstone, mudstone, limestone, and conglomerate. It appears that the Triassic units were deposited II-9 along the margins of great, open seas and restricted inland basins that had existed since Paleozoic time. As the shorelines of these seas moved in response to orogenic episodes and basin filling, the specific environments in the GRA changed from marine to terrestrial. During this time, shallow-water and near-shore swamps were formed. In other areas of Colorado, these Upper Triassic near-shore sediments are the host for copper-silver "redbed" deposits that were deposited in areas of rapidly changing Eh-pH conditions in the aqueous solutions within the rock strata. The presence of these deposits within the GRA and in other, widely dispersed areas of western Colorado is ample evidence that conditions favorable for these types of environments did, indeed, exist in the Triassic Period. The Navajo Sandstone outcrops in the western portion of the GRA and is thought to represent a period of inland sand dune accumulation in a terrestrial desert envi- ronment (Carter et al, 1965). This Triassic- Jurassic unit thins to the east and probably was not deposited on top of the Uncompahgre Uplift (Baars et al, 1981). The unconformity between the Navajo Sandstone and the overlying Jurassic Entrada Formation is probably a local feature that represents a period of non-deposition. The Navajo is known to exist only in selected, desert environments or basins, and may have never been deposited in some areas west of the Uncompahgre Uplift. The Jurassic Entrada, however, is thought to have been deposited during a period of terrestrial fluvial and eolian deposition in small, restricted basins that eventually coalesced and buried the majority of the Uncompahgre Uplift features (Carter et al, 1965). The Navajo-Entrada unconformity may then represent a period when the last remnants of the Uncompahgre topographic high were being eroded into flanking shallow Jurassic basins. The Jurassic Summervllle and overlying Morrison Formations were being deposited in near-shore lagoonal environments, or shallow water marine and fuvial systems. Some fresh-water lacustrine and fresh-water fluvial deposits have also been identified from these rocks. As in the earlier Triassic section, mineral deposits are commonly found associated with limey sandstones, shales, and siltstones that were deposited in shallow, neritic basins that had fluvial channels meandering through them. Copper-silver-uranium-vanadium mineralization occurs in these units as roll-front and organically precipitated "stream-channel" deposits. "St ream- channel" deposits occur where uranium-vanadium waters encountered structural traps and/or clastic organic accumulations, and deposited minerals In a reducing environment. Such mineral deposits are very important economically as they contain high grade uranium-vanadium ores , and are known to occur throughout the GRA. These deposits are thought to have been emplaced in an environment similar to that of the present lower Mississippi Basin. Fossil-plant material from this period is indicative of a tropical environment that was adjacent to an active fluvial or lacustrine system. During Lower Cretaceous time, the area was the site of shallow water deposition In a lagoonal or swamp environment. The Lower Cretaceous Burro Canyon Formation appears to have been deposited in a series of meandering river systems with adjacent terrestrial lakes. The terrestrial, clastic nature of this formation is thought to be characteristic of a beach or littoral environment (Young, 1955). The Upper Cretaceous Dakota Sandstone unconformably overlies the Burro Canyon Formation, and was probably deposited on an irregular upper surface of Burro Canyon rather than a true erosion surface (Carter et al, 1965). Portions of the Dakota are found as channel fillings in the Burro Canyon paleosurface. From fossil evidence, it appears that the lower sections of the Dakota were deposited in 11-10 shallow basins or stream channels and having as the source of the material eroding masses of Pennsylvanian and Pemian rocks, that were then exposed (Carter et al, 1965). The medial carbonaceous shales of the Dakota are known to contain abundant plant remains, and were probably deposited in a near-shore swamp or lacustrine environment. Thin coal beds are known to exist within the Dakota in certain areas and these may have economic potential. During the Tertiary, the thick Pennsylvanian salt sequences and the overlying Paleozoic and Mesogoic clastic, terrestrial sediments were folded and uplifted along the flanks of the Uncompahgre Plateau. The evaporitic sequences actually were squeezed into topographic highs within the areas of the sedimentary basins (i.e., Sinbad Valley, Castle Valley and Paradox Valley), which were subjected to rapid erosion (Cater, 1955). During this time, at least two periods of major uplift along the Uncompahgre Plateau have been identified. These orogenic episodes caused highlands to be formed which may have had topographic relief equivalent to the present day Front Range near Denver, Colorado. This area shed sediments into the ancestral Colorado River and the major Uinta and Wasatch basins of northwestern Colorado. Within the GRA, the entire Upper Cretaceous and Tertiary section is missing, indicating that it was probably never deposited within the study area. This was a time of mountain building, base and precious metal mineralization and sedimentation in shallow, broad basins (Carpenter, Personal Communication, 1982). Within the GRA, the dominant processes that were evolving the region were tectonic and orogenic rather than sedimentary (Cater, 1955; Baars, et al, 1981). The unconformably overlying Quaternary fluvial, eolian, colluvial and alluvial deposits represent periods of erosion and fluvial deposition. These units contain fragments of the Precambrian, Paleozoic and Mesozoic stratigraphy that were exposed and being eroded since the Tertiary. THE PALISADE/GRANITE CREEK WSA (CO-070-132/132A) The basal Precambrian section of quartz-feldspar, and quartz-biotite gneisses contains schists that have been intruded by older and younger Precambrian granites, aplites, pegmatites and lamprophyres. It is exposed in the eastern and northern portions of the WSA. The units are moderately deformed and were probably uplifted into their present position by various episodes of the Uncompahgre Orogenic Sequence (Baars, 1981). Base and precious metal deposits associated with these lithologies have been found in the adjacent, Unaweep Canyon area (Schwochow, 1978). The entire pre-Permian Paleozoic section is not found within the WSA. An unconfor- mity exists between the Precambrian and Permian Cutler Formation, which probably represents a period of non-deposition during which most of the WSA was undergoing uplift as a part of the Uncompahgre Orogenic Sequence. The Permian Cutler Forma- tion is thought to represent a period of clastic deposition on the flanks of the Uncompahgre Uplift. The mesozoic rocks exposed within the WSA are thought to represent periods of fluvial and lacustrine deposition in a terrestrial environment. The lacustrine deposits of the Triassic Moenkopi Formation contain thin gypsum and anhydrite beds which may have local economic potential. In other areas of Utah and Colorado, the Chinle Formation is the host for major uranium-vanadium deposits. Within the GRA, 11-11 Lht« unit and the overlying Wlngate Sandstone is known to contain copper-silver deposits that have been mined in the past. Within the WSA, no mineralization of this type has been reported. The Chinle, Wlngate, and Kayenta Formations of the Glen Canyon Group are thought to represent a time of Triassic sedimentation in a near-shore environment with episodes of eolian deposition of cross-bedded sand- stones. Fluvial portions of the sequence include fresh water sandstone, shale, siltstone and mudstone with interbedded impure limestone units. Though the information pertaining directly to the WSA is limited, it is reasonable to assume that the Triassic environments favorable for syngenetic copper-silver mineraliza- tion may have existed In this area during this period. The Jurassic rocks exposed in the WSA are thought to represent a period of fluvial and eolian deposition in small, restricted basins. The existing outcrops of the Jurassic Entrada Summerville, and Morrison Formations have been heavily prospected for uranium/ vanadium mineralization. Airborne, radiometric anomalies were followed up by the Department of Energy and other government agencies under a number of different programs. Conditions favorable for uranium-vanadium mineralization are thought to exist in this general suite of Jurassic rocks, but the only known mineralization is found associated with a stream channel in the Morrison on the top of The Palisade ridge, and was investigated by the MSME/Wallaby field team (Gilmour, Field Notes, 1982). Subsequent to Jurassic time, the area underwent uplift and erosion. No post-Juras- sic Mesozoic or Cenezoic rock units are known to exist within the boundaries of the WSA. Quaternary alluvial and colluvial sedimentary deposits exist along West Creek and the Dolores River Valley areas. These units have provided sand and gravel material for local use in the past and are thought to represent an industrial mineral resource (BLM/MRI Maps and File Data). SEWEMUP MESA WSA (CO-070-176) Within the boundaries of the WSA, the Precambrian section Is not exposed. The Precambrian units are thought to underlie this area, but have been found only in upfaulted blocks that are within 10,000 feet of the present surface. This was a time of intrusion of granitic bodies into the older Precambrian sequence of gneiss, schist and intrusives. The drilling in the adjacent Sinbad and Paradox Valleys has encountered granitic units at depths of 10,000 to 15,000 feet (Baars et al, 1981). The pre-Pennsylvanian Paleozoic section is not exposed within the study area, but may exist at some depth under the WSA. During this period of early and middle Paleozoic deposition, basins formed along the margins of the Uncompahgre Uplift were receiving sediments from the adjacent terrestrial highlands. These basins were filled with clastic and marine sediments and were, in turn, downfaulted into mobile rift zones. During Pennsylvanian times, thick evaporite sequences were laid down in these basins and subsequently deformed by tectonic stresses into salt anticlinal and domal features (Baars et al, 1981). This period of tectonic activity may have been responsible for the circular feature that has been mapped in the Garvey Gulch-Rajah Mine Area (Shoemaker, 1956). Directly west of the Rajah Mine, the clastic units of the Permian Cutler Formation are in contact with the Triassic Moenkopi Formation. It thus appears that the Cutler may also be present within the boundaries of the WSA. This unit represents a period of clastic deposi- tion directly adjacent to a terrestrial highland. It is thought that this sedimentation continued until the Precambrian and Lower Paleozoic topographic highs were inundated by sediments. It is thought that this unit was deposited as a fanglomerate adjacent to a rapidly eroding terrestrial high (Shoemaker, 1956). 11-12 The basal units exposed within the WSA include the Triassic Moenkopi, Chinle and Wingate Formations. The Moenkopi is thought to represent a period when shallow water lacustrine and fluvial systems were being formed, received clastic material, and dried up leaving thin, evaporite beds that may contain economically important gypsum deposits (Williams, 1964). The Chinle and Wingate Formations outcrop in the bottom of the canyons that cut and border the WSA. These units and the overlying Kayenta Formation are thought to represent a period of Triassic sedimentation in a near-shore environment with episodes of eolian deposition. From the observation of our field team and examination of the literature, it appears that copper-silver mineralization was deposited syngenetically with the rock units, and that tectonic processes aided in the localization of the deposits. Widespread occurrence of copper-silver mineralization in the Triassic rocks of western Colorado is thought to represent a "red-bed" depositional environment that existed in certain fluvial systems (Gilmour, Personal Communication, 1982). The ore deposits that have been mined in the past are located along major fracture systems that localized and concentrated the mineralization (Fisher, 1936; and Holmes et al, 1952). Within the study area, the Triassic Chinle Formation is not known to contain uranium-vanadium deposits as it does in the Lisbon Valley of southeastern Utah. There is potential for these deposits within the WSA, as it is known that the Lisbon Valley deposits are found in association with particular lithologic units that may exist in the WSA. The Triassic Kayenta Formation outcrops as resistant benches and ledges throughout the WSA, and is thought to have been deposited in a fluvial environment. The Tri- assic- Jurassic Navajo Sandstone Formation is thought to have been deposited in a terrestrial, desert environment (Carter et al, 1965) that appears to have been adjacent to a portion of the Uncompahgre Uplift. The Jurassic sequence is represented by a few outcrops of the Entrada and Summer- ville Formations in the northern portion of the WSA. These units were deposited in fluvial and lacustrine environments that were adjacent to near-shore lagoons. The outcrops of the Jurassic Morrison Formation found in the vicinity of the Rajah Mine and on the mesa tops in the northern part of the WSA are thought to have been deposited in a fluvial environment. Uranium-vanadium-copper mineralization has been found associated with the Salt Wash Member of the Morrison in the vicinity of the Rajah, and other prospects to the northwest along the boundary of the WSA. Mineralization commonly occurs in the Salt Wash Member associated with "roll fronts" and accumulations of organic material in meandering fluvial systems (Shoemaker, 1956). Subsequent to Jurassic time, the area underwent uplift and erosion. No post-Juras- sic Mesozoic or Cenezoic deposits are known to exist within the boundaries of the WSA. Quaternary alluvial and colluvial deposits exist in the Salt Creek and Dolo- res River Canyon areas, and are known to represent a sand and gravel resource (BLM/ MRI Maps and File Data). Minor gold production is also reported from these units. Figures II-l through 11-10 illustrate and describe some of the unique character- istics of the subject WSA's. 11-13 THE PALISADE FIGURE 11-2 Adit in uranium prospect on the Palisade in Morrison formation. FIGURE 11-1 The Palisade. .. J *>■/ < THE PALISADE 11-14 FIGURE 11-3 Closeup of carbonized wood and carnotite uranium prospect. THE PALISADE FIGURE 11-4 Unaweep Canyon, looking E toward valley of Colorado River and Grand Mesa. Mesozoic section overlying Precambrian gneiss cut by granitic "sills". THE PALISADE 11-15 SEWEMUP MESA FIGURE 11-6 Outlier of Morrison formation overlying Summerville-Entrada in northern extremity of mesa. FIGURE 11-5 Sinbad Valley. Near Sewemup Mesa. Valley underlain by Paradox formation and evaporites. Gypsum in white outcrops. SEWEMUP MESA 11-16 FIGURE 11-7 d Wingate sandstone suitable for dimension stone. SEWEMUP MESA ; Wingate_ sandstone Copper Rivet _^ horizon r Chinle- ■t', < :i'.'\ .; FIGURE 11-8 SEWEMUP MESA East side of WSA, in valley of Dolores River (viewed from Hwy. 141). "Copper Rivet horizon" marked by grey-green (reduced?) shale and white staining (iron sulphate?). 11-17 c o « N c a a FIGURE 11-9 SEWEMUP MESA Looking E at faulted, mineralized Wingate/Chinle contact. FIGURE 11-10 Copper Rivet Mine. Closeup of copper mineralization at or near base of Wingate sandstone. SEWEMUP MESA 11-18 SECTION III ENERGY AND MINERAL RESOURCES KNOWN MINERAL DEPOSITS The known mineral deposits in the Palisade/Granite Creek-Sewemup Mesa GRA consist of a large number of uranium-vanadium mines, and minor deposits of sand and gravel, gypsum, gerastone, construction stone, and placer gold. There are no known coal mines, or gas or oil wells in the GRA. The number and type of uranium-vanadium mines in the GRA are summarized below: Producer Past Producer Status Unknown Total 41 167 130 338 (Overlay B, and Appendix B) These mines occur in the sandstone and mudstone layers of the Triassic Chinle For- mation, and Jurassic Morrison Formation. These rock units will be described in detail in following sections. One sand and gravel, and gypsum deposit occurs in T51N R19W, Section 35, along the Dolores River (USGS, Gateway 7-1/2', Colorado, Appendix A; and Overlay D, #3). The operational status of this desposit is not known. Two more sand and gravel pits are evident at T15S, R102W, Sec. 10; and T15S, R103W, Sec. 2 (USGS, Fish Creek 7-1/2", Colorado, Appendix A). The gemstone mines occur in the northeast section of the GRA. These are included in T14S, R101W, Sec 34; and T155, R101W, Sec. 7 (Overlay D). The status of these deposits is also unknown. Overlay D shows the location of seven inactive pits for construction stone and bor- row material. These are situated in the western part of the GRA. The gold deposit in the GRA occurs as a placer mine at T48N, R18W, Sec. 4 (Overlay B, #563), along the Dolores River. As before, the status of this deposit is unknown . THE PALISADE/GRANITE CREEK WSA (CO-070-132/132A) The known mineral deposits within this WSA consist of uranium workings, two uranium mines, and a sand and gravel mine. The uranium deposits include workings in the Jurassic Morrison Formation on The Palisade, and on the flanks of other high mesas (Field Notes, Appendix A). One uranium mine, the Palisade mine, was noted in the WSA by the consultants in the Morrison Formation, Salt Wash Member. The consul- tants commented that the mine is inaccessible without a helicopter (Field Notes, Appendix A). The second uranium mine is located at T51N, R19W, Section 10 (Overlay B, #217). This mine, named PPT Concentrate, is known to be a past producer. The sand and gravel mine in the WSA is locted at T15S, R103W, Sec. 28 (Overlay D, #7, and USGS, Gateway 7-1/2', Colorado, Appendix A). The status of all these mines in unknown. III-l SEWEMUP MESA WSA (CO-070-176, CO-030-310A) The Seweraup Mesa WSA does not contain any mines or mineral deposits that have been defined by drilling or other three dimensional exposures. KNOWN PROSPECTS, MINERAL OCCURRENCES, AND MINERALIZED AREAS The known prospects, mineral occurrences, and mineralized areas of the Palisade/ Granite Creek-Sewemup Mesa GRA consist mainly of energy minerals, and base and precious metals. In looking at uranium prospects, there are two known prospects, and fourteen miner- al occurrences (Overlay B, Appendix B). The USGS topographic map for Gateway, Colorado (Appendix A), also shows a uranium occurrence in the middle of the GRA. The current status of these prospects is unknown. Coal occurs in the sourthern portion of the GRA (USGS, Gateway 7-1/2', Colorado, Appendix A). In addition, the GRA contains a number of known coal fields, includ- ing the Grand Mesa Coal Field (Overlay C). Gold and copper occurrences are noted in the GRA. Mineralized areas favoring plac- er gold deposits along the Unaweep Canyon are delineated on the USGS Map, Fish Creek, Colorado (Appendix A). Seven copper prospects are shown on Overlay B. The extent of development and current status are unknown. In general, seventeen prospects are shown on Overlay B for unknown commodities (refer also to Appendix B). The GRA also contains three exploration holes (Overlay C). THE PALISADE/GRANITE CREEK WSA (CO-070-132/132A) The WSA contains a few occurrences for specific minerals. Generally, there is mining activity in the northwest and western section of the WSA, as well as on the north and east section and subsequent borders (USGS, Polar Mesa 7-1/2', Utah, Colorado; Gateway 7-1/2', Colorado, Appendix A). Some old prospects are located in T15S R103W (Aerial Photo 1-30W-6, Appendix A). There is no coal, oil, or gas present in the WSA. It does not contain any known coal, oil, or gas fields. The southwest border, however, is close to a coal field (refer to Overlay C). The Dakota Sandstone, known to be coal bearing in other parts of Colorado, is present in the WSA as mesa caps. Gold and uranium are the only specific mineral occurrences in the WSA. Along the northern Unaweep Canyon are rock types favorable to the deposition of placer gold (USGS, Gateway 7-1/2', Colorado, Appendix A). There is a uranium occurrence at T15S R104W, Sec. 36 (Field Notes, Appendix A). SEWEMUP MESA WSA (CO-070-176, CO-030-310A) Known mineralized areas and prospects have been delineated in the WSA through field examination and aerial photo interpretation. III-2 In the southern portion of the WSA, stratabound copper-silver mineralization was observed along the southeastern wall of Salt Creek Canyon in Section 10, T49N, R19W (Appendix A, Field Notes). Air photo interpretation has delineated potential Copper Rivet type mineralization southeast of Salt Creek. Canyon, trending in a northeasterly direction for a length of 2.5 miles (BLm Photo 1/3/25). The same stratigraphic horizon containing the Copper Rivet type mineralization was again observed on the east side of the WSA from Highway 141 which follows the Dolores River Canyon. The mineralization is marked by a gray-green shale and white stain- ing. From the above mentioned observations of stratabound copper mineralization, it is possible that the copper potential would extend beneath all of the WSA. The following prospects are located within the WSA: Type 1. Copper prospect (Colorado Copper Co. Claim 9) 2. Uranium- Vanadium Prospects 3. Oil-Gas Exploration 4. Drilling (Cu) Location T49N, R19W, Sec. 10 T49N, R19W, Sec. 1 T49N, R19W, Sec. 15 T48N, R19W, Sec. 1 Operating Status unknown unknown dry hole unknown The copper prospect lies at the southern extension of the potential Copper Rivet type mineralization as delineated on aerial photograph 1-3-25 (Appendix A). The prospect, also known as the Colorado No. 9 Claim is briefly described in a U.S. Bureau of Mines Report of Investigations by R.V. Holmes and CM. Harrer (Appendix A). The uranium-vanadium prospect lies on a small outlier of the Morrison Formation found in the northern portion of the WSA. This outlier can be seen on aerial photograph 1-3-25. The extent of development and current status of the prospect is unknown . The oil/gas drilling pad is located approximately one mile south-southeast of the above mentioned copper prospect, along the southwestern edge of Sewemup Mesa. The depth of the drill hole and the company that completed the drilling is unknown. Exploration drill holes, located in the extreme southern portion of the WSA, are delineated on aerial photograph 1-4-21 (Appendix A). The exploration drill holes, situated inside and outside of the WSA boundary, are in the Chinle and Wingate formations. Within the WSA, there may be a potential for salts, brines and multi-metals associ- ated with the Paradox Member of the Hermosa Formation. However, at this time, it can only be inferred from regional evidence. III-3 MINING CLAIMS, LEASES AND MATERIAL SITES As of June, 1982, approximately 7,280 unpatented lode and placer claims were loca- ted in this GRA (Overlay A and Appendix C). Unpatented lode claims comprise 98% of this total number. An exact figure could not be obtained since mining claims that are situated across a section boundary or township, range boundary are often listed twice in the Geographic Index. It is estimated that the above figure is accurate within 150 claims. The unpatented claims are primarily located south of The Palisade/Granite Creek WSA and are densely situated northwest, northeast, east and south of the Sewemup Mesa WSA. Approximately 95% of the unpatented claims are controlled by Union Carbide, Minerals Engineering Company, Pioneer Uravan, Houston Oil and Minerals, Colorado Air Drilling, Energy Reserve Group, Cotter Corporation, Foote Minerals and Atlas Corporation. The GRA contains about 48 patented mining claims located south, east and north of Sewemup Mesa. Information regarding leases and material sites was obtained only if the occurrence was in or bordered the WSA's. Please refer to the Oil and Gas Plats and Master Title Plats in Appendix A. THE PALISADE/GRANITE CREEK WSA (CO-070-132/132A) As of June 1982, no patented mining claims, were located in the WSA. The unpatented mining claim data was obtained from the Bureau of Land Management Geographic Index (Appendix C). Since the Geographic Index only locates claims by township, range, section and quarter-section, it is not possible to accurately determine the number of unpatented mining claims. There are 90 unpatented mining claims in the sections contained within the WSA or are cut by the WSA boundary (refer to Overlay A). It is estimated that 60 of the 90 unpatented claims lie within the WSA. This estimation was derived by using the quarter-section sub- divisions provided in the Geographic Index. An accurate number of unpatented mining claims can be obtained through the research of location notices and maps. The majority of unpatented mining claims lie in sections 1,2,3,11,12,22,27 and 34, T15S, R104W and section 34, T14S, R104W. For information on leases, please refer to the Oil and Gas Plats in Appendix A. SEWEMUP MESA WSA (CO-070-176, CO-030-310A) Three patented claims are situated near or adjacent to the extreme southern bound- ary of the WSA (Overlay A and Master Title Plats). As of June 14, 1982, approxi- mately 75 unpatented lode mining claims and one unpatented placer claim were situated in the WSA (Overlay A). Since the Geographic Index (Appendix C) only locates claims to within a quarter-section, an exact figure can not be obtained. For information on lease location, refer to the Oil and Gas Plats in Appendix A. MINERAL DEPOSIT TYPES The deposit types in The Palisade/Granite Creek-Sewemup Mesa GRA consist of uranium and vanadium, sand and gravel, gypsum, gemstone, construction stone, and minor placer gold. III-4 The uranium and vanadium deposits occur in the Jurassic Morrison Formation and the Triassic Chinle Formation. In the Morrison Formation, carnotite, a uranium and vanadium oxide, is the principal ore mineral. Carnotite is a secondary mineral deposited by waters that were in contact with primary uranium and vanadium minerals. Uranium mineralization occurs in the Salt Wash Member and the Brushy Basin Member of the Morrison Formation. The Salt Wash Member consists of inter- stratified sandstone and claystone units. The unit was formed as a large alluvial fan by an aggrading system of braided streams (Craig et al, 1955). The Brushy Basin consists of variegated claystones with few lenticular conglomeritic sandstone strata. The Brushy Basin was formed in fluvial and lacustrine environments with large amounts of clay (Craig et al, 1955). It is thought the introduction of the ore was done by mineral-bearing solutions that seeped through the permeable layers after sediments accumulated. The source of the primary minerals in currently under dispute (Craig et al, 1955). The Triassic Chinle Formation is composed of red and gray shales and slltstones; sandstone beds, which may be conglomeratic and thin layers of limestone and limestone conglomerate (Fisher, 1956). The Chinle uranium deposits are primarily in the conglomeratic sandstone. The sand and gravel deposits occur along the Dolores River Valley. Valley-fill deposits of durable igneous rock derived from San Juan Mountains has been mapped in the Dolores River Valley. However, the prominent alluvial fans of coarse sand and sandstone fragments derived from Precambrian, Triassic, and Jurassic Formations are much more important (Schwochow, 1978). The lower edge of some of these fans exposes well-rounded and sorted gravel of Dolores River origin (Schwochow, 1978). The potential for economic evaporite minerals is most strong in the Sinbad Valley area in the southwestern part of the GRA (Refer to Figure 1-1). The Sinbad Valley is a salt anticline, a structural feature thought to have originated by the intrusion of overlying rocks by salts and other evaporites, which have a tendency to deform plastically under great pressure (Schwochow, 1978). The core of the Sinbad Valley Anticline is composed of gypsum and halite (Schwochow, 1978). The beryl, flourite and amethyst gemstone material in the GRA may be produced from the veins of silicates present in the GRA (Schwochow, 1978). No further informa- tion on these deposits was available. Construction stone has been produced from the upper Wingate Sandstone and the Salt Wash Member of the Morrison Formation. The Wingate Sandstone yielded a light reddish- brown, fine-grained, well cemented feldpathic sandstone. The Salt Wash Member has yielded thin beds of dense, crystalline gray limestone (Schwochow, 1978). The placer gold occurs along the Dolores River. No further information was avail- able as to the origin of these deposits. The following addresses the mineral deposit types of each of the WSA's in The Palisade/Granite Creek Sewemup Mesa GRA. PALISADE/GRANITE CREEK WSA (CO-070-132/132A) The deposits in The Palisade/Granite Creek WSA consist of uranium-vanadium deposits in the Morrison Formation (please refer to the preceding discussion), and sand and gravel along the Unaweep Canyon. III-5 Sand and gravel deposits found in the Unaweep Canyon area consists of coarse- grained sand and pebbles which are a result of disintegration of Precambrian granite. This area is composed of a series of alluvial fans composed of sandstones and Precambrian rocks (Schwochow, 1978). SEWEMUP MESA WSA (CO-070-176, CO-030-310A) The Seweraup Mesa WSA contains no known deposits, however, a prominent type of cop- per mineralization, known as Copper Rivet, is worth discussion. Copper mineralization occurs as copper, fluorite and gem-bearing quartz veins in the Triassic Chinle Formation. The Chinle consists of red shales, siltstones, mud- stones and sandstones. Overlying the Chinle Formation is the Triassic Wingate Sandstone. Mineralization in the Chinle Formation occurs at or near the Chinle- Wingate contact (Schwochow, 1978; and Gilmour, Personal Communication, 1982). MINERAL ECONOMICS The inherent nature of discussing the economics of the minerals existing within The Palisade/Granite Creek-Sewemup Mesa GRA and its WSA's can only provide for a general approach inasmuch as there are many economic factors that enter into the development of an ore body. These include access, market value, grade, transporta- tion, recovery and extraction methods, etc. Therefore, the discussion herein addresses the U.S. and Colorado demand and production status of each of the exist- ing minerals in the WSA. The mineral resources found in this GRA include uranium, vanadium, sand and gravel, gypsum, gemstone, construction stone, and some placer gold. Energy mineral occurrences (uranium-vanadium) in the GRA are known in the Jurassic Morrison and Triassic Chinle Formations. Uranium-vanadium deposits occur as roll front deposits. Current uranium-vanadium production is down from past production levels due to a general drop in the price of uranium (Eng. & Ming. Journal, Dec. 1982). Uranium and vanadium are currently being produced at very little or no profit by many of the major mining operations in Colorado (Carpenter, Personal Communication, 1982). Currently, 41 producing uranium- vanadium mines are located in the GRA. Production statistics for these mines was not available. Industrial minerals in the GRA can be placed into two groups. The first group; construction stone, and sand and gravel, are considered to be "high place value" industrial minerals (Eyde, Personal Communication, 1982). High place value minerals are of economic value only when deposits are readily accessible, and in close proximity to a market. In the second group, gypsum and gemstone resources are considered to have a "high unit" value, that is, they are of economic value wherever found as the commodity value normally exceeds transportation costs (Eyde, Personal Communication, 1982). Generally, high place value minerals have almost no economic value in the GRA when the location is remote from urban markets. Conversely, high unit value minerals in the GRA are of potential economic value (Eyde, Personal Communication, 1982). III-6 Gold in the GRA usually occurs as placer deposits. Sources of these deposits are usually credited to the Colorado and Gunnison Rivers (Schwochow, 1978). Currently, a strong demand for gold exists in Colorado and the U.S. due to high prices. Production and reserves are not known for the GRA. The economic viability of the mineral resources in the WSA's in the Palisade/ Granite Creek - Sewemup Mesa GRA are summarized as follows: WSA Palisade/Granite Creek WSA (CC-070-132/132A) Sewemup Mesa WSA (CO-070-176) MINERAL POTENTIAL ACCESSIBILITY ECONOMIC POTENTIAL [a] Copper-silver as fair poor to fair "red bed" deposits* Uranium-vanadium fair fair Sand and Gravel good good Oil and gas* poor poor Copper-silver* poor poor-fair *Occurs as outcrops or mineralized areas, no further information is known. [a] The economic potential rating is notwithstanding market demand fluctuations III-7 SECTION IV LAND CLASSIFICATION FOR GEM RESOURCES POTENTIAL After thoroughly reviewing the existing literature and data base sources, MSME/ Wallaby personnel plotted all known mineral occurrences, mines, prospects, oil and gas fields, sand and gravel operations, processing facilities, mining claims, min- eral leases, and the locations of anomalous geochemical samples from the National Uranium Resource Evaluation - Hydrological Stream Sediments Reconnaissance Airborne Radiometric and Magnetic Survey (NURE-HSSR-ARMS) programs. This plotted information and the data bases on each WSA was made available to a multi-faceted team of experts which made three successive evaluations of the GEM resource poten- tial of each of the WSA's. The team or panel of geological experts was comprised of: Dr. Paul Gilmour: Base and precious metal deposits in western U.S. and Canada, expert on Precambrian mineral resources. Mr. Ted Eyde: Base and precious metal deposits in western U.S., expert on Indus- trial mineral resources. Mr. Annan Cook: Base and precious metal deposits in western U.S., expert on porphyry deposits and mine evaluation. Mr. Edward Heylmun: Oil, gas and oil shale deposits of western U.S. Dr. Robert Carpenter: Mineral deposits of Colorado and western U.S., expert on geology of Colorado. Dr. Donald Gentry: Expert in coal and oil shale deposits of Colorado and western U.S. Dr. Larry Lepley: Expert in remote sensing and geothermal resources; Mr. Walter E. Heinrichs: Geophysics and base and precious metal deposits of west- ern U.S., expert on porphyry copper deposits. As indicated earlier, Dr. Gilmour and Messrs. Cook and Eyde made certain field investigations as result of the base data analysis phase. The purpose of the field investigations was to either verify the existing data or assess relatively unknown areas. Dr. Lepley reviewed all aerial photographs for observable anomalies, which were then investigated by the field team, or verified against the existing base data. The evaluations were then made on the basis of examination of the data bases, field investigations and the individual experiences of the members of the panel in such areas as base and precious metal, industrial and energy mineral deposits; oil and gas deposits; and geothermal resources. In the course of these evaluations, every attempt was made to objectively rate the potential for a particular commodity with- in the respective study area. In this effort, the evaluation criteria proposed by the Bureau was rigorously used. The classification scheme used is shown in Table IV-1. In many cases the lack of information did not allow for a full determination of the GEM resource potential and the panel was forced to leave some areas unranked IV-1 or classified for some commodities. The situation thus arises where there is an area that has been unclassified for a commodity, despite it's reported occurrence, because it is next to an area where there is insufficient data to make a meaningful attempt at classification. Nonetheless, each resource has been additionally rated as to what level of confidence the panel of experts attached to their selection of classification level. This is denoted by the letter association with each rate classification. These are defined in Table IV-1. A further restraint on this classification and delineation effort comes in the area of the lack of subsurface information. Some areas are very well known from past exploration efforts and have an abundance of subsurface information. Other areas are practically unknown due to an absence of any past exploration or development efforts . The WSA's, for the most part, are not well known geologically. For this reason, our expert team had to extrapolate geologic information from adjacent areas to make any sort of reasonable classification with some level of confidence. The following pages address those resources considered to be leasabale, locatable, and/or salable with associated maps (Figures IV-1 through IV-3) locating the resource areas. IV-2 TABLE IV-1 RESOURCE RATING CRITERIA CLASSIFICATION SCHEME 1. The geologic environment and the inferred geologic processes do not indicate favorability for accumulation of mineral resources. 2. The geologic environment and the inferred geologic processes indicate low favorability for accumulation of mineral resources. 3. The geologic environment, the inferred geologic processes, and the reported mineral occurrences indicate moderate favorability for accumulation of mineral resources . 4. The geologic environment, the inferred geologic processes, the reported mineral occurrences, and the known mines or deposits indicate high favorability for accumulation of mineral resources. LEVEL OF CONFIDENCE SCHEME A. The available data are either insufficient and/or cannot be considered as direct evidence to support or refute the possible existence of mineral resources within the respective area. B The available data provide indirect evidence to support or refute the possible existence of mineral resources. C. The available data provide direct evidence, but are quantitatively minimal to support or refute the possible existence of mineral resources. D. The available data provide abundant direct and indirect evidence to support or refute the possible existence of mineral resource. IV-3 LEASABLE RESOURCES THE PALISADE /GRANITE CREEK WSA (CO-070-132/132A) Resource Oil & Gas Coal Geo thermal Classification 2B 1A 2B Comments There is the possibility of a major over- thrust fault at depth. If this is the case then favorable sedimentary strata could exist at depth. The WSA lacks coal-bearing formations. Unknown potential in the Paradox Formation. SEWEMUP MESA WSA (CO-070-176) Resource Classification Oil & Gas Coal Salts Brines Potash Geo thermal 3D 1A 3C 3B 3B 2B Comments The WSA is located on the east flank of the Sinbad Valley Salt Anticline in the Paradox Basin. Structural and stratigraphic con- ditions for oil and gas could be favorable throughtout a 15,000 foot section of sedi- mentary strata of Pennsylvanian, Mississipplan and Devonian age. Lack of coal-bearing formations. Known to occur in the Hermosa Member of the Paradox Formation. same as above same as above Unknown potential. IV-4 CO-070-132 R 104 W The Palisade R 103 W 5 Miles MMS/ LEASABLE RESOURCES Figure IV- la IV- 5 (After BLM. 1980) CO 070-1 32A Granite Creek 5 Miles MMS/LEASABLE RESOURCES Figure IV-lb (After BLM, 1980) IV- 6 CO030 310A CO 070-176 Sewemup Mesa C0AL[PV] R 19 W R 18 W ■'. ■ . * J 5 MiiQMMS/LEASABLE RESOURCES Figure IV- lc (After BLM. 1980) IV-7 LEGEND FOR MINERALS MANAGEMENT SERVICE CLASSIFICATIONS Defined KGS and/or Coal Leasing Areas p Areas Prospectively Valuable for Sodium or Potassiur L 51 Defined Oil Shale Leasing Area J Coal [PV] OG[PV] Areas Identified as Prospectively Valuable for Coal or Oil, Gas Coal [NPV] OG [NPV] Areas Identified as Not Being Prospectively Valuable for Coal, or Oil, Gas IV-8 LOCATABLE MINERALS PALISADE /GRANITE CREEK WSA (CO-070-132 & CO-070-132A) Resource Classification Comments Precious Metals 3C 3B Base Metals 3C 3C 3B Ag, mineralization associated with Triassic Chinle and Wingate Formations, nearby pros- pects, mines with production. Au, Ag mineralization potential associated with Precambrian felsic volcanics and sedi- ments, nearby prospects, placers, minor production. Au placers nearby in Quaternary alluvium. Cu mineralization associated with Triassic Chinle and Wingate Formations, nearby pros- pects, mines with production. Cu, Pb, Zn mineralization potential associ- ated with Precambrian felsic volcanics and sediments, nearby prospects, minor, produc- tion. Locatable Energy Minerals 4D 2B Other Locatable Minerals 3C Uranium-Vanadium mineralization in Salt Wash Member of the Jurassic Morrison Forma- tion. Existing mine with past production. Uranium-Vanadium mineralization in Triassic Chinle Formation. Gypsum is known to occur in the Paradox Hermosa Member of the Hermosa Formation and in the Triassic Moenkopi Formation. SEWEMUP MESA WSA (CO-030-353) Resource Classification Precious Metals 4D Comments Ag, mineralization associated with Triassic Chinle and Wingate Formations, adjacent mines with production that extend onto the WSA. 2A 3C Au, Ag mineralization potential associated with Precambrian felsic volcanics and sedi- ments that may be present at depth. Au, Ag placers reported from Quaternary gravels in adjacent areas. IV- 9 LEGEND FOR MINERALS MANAGEMENT SERVICE CLASSIFICATIONS Defined KGS and/or Coal Leasing Areas V Areas Prospectively Valuable for Sodium or Potassium L H Defined Oil Shale Leasing Area J Coal [PV] OG[PV] Areas Identified as Prospectively Valuable for Coal or Oil, Gas Coal [NPV] OG [NPV] Areas Identified as Not Being Prospectively Valuable for Coal, or Oil, Gas IV-8 LOCATABLE MINERALS PALISADE /GRANITE CREEK WSA (CO-070-132 & CO-070-132A) Resource Classification Comments Precious Metals Base Metals Locatable Energy Minerals Other Locatable Minerals 3C 3B 3C 3C 3B 4D 2B 3C Ag, mineralization associated with Triassic Chinle and Wingate Formations, nearby pros- pects, mines with production. Au, Ag mineralization potential associated with Precambrian felsic volcanics and sedi- ments, nearby prospects, placers, minor production. Au placers nearby in Quaternary alluvium. Cu mineralization associated with Triassic Chinle and Wingate Formations, nearby pros- pects, mines with production. Cu, Pb, Zn mineralization potential associ- ated with Precambrian felsic volcanics and sediments, nearby prospects, minor, produc- tion. Uranium-Vanadium mineralization in Salt Wash Member of the Jurassic Morrison Forma- tion. Existing mine with past production. Uranium-Vanadium mineralization in Triassic Chinle Formation. Gypsum is known to occur in the Paradox Hermosa Member of the Hermosa Formation and in the Triassic Moenkopi Formation. SEWEMUP MESA WSA (CO-030-353) Resource Classification Precious Metals 4D 2A 3C Comments Ag, mineralization associated with Triassic Chinle and Wingate Formations, adjacent mines with production that extend onto the WSA. Au, Ag mineralization potential associated with Precambrian felsic volcanics and sedi- ments that may be present at depth. Au, Ag placers reported from Quaternary gravels in adjacent areas. IV- 9 CO070-132 R 104 W The Palisade R 103 W 5 Miles (After BLM, 1980) LOCATABLE RESOURCES Figure IV- 2a IV- 10 CO070 132A Granite Creek R 104 W lE^K J 5 Miles LOCATABLE RESOURCES Figure IV- 2b (After BLM. 1980) IV- 11 CO-030-310A CO-070 176 Sewemup Mesa R 19 W R 18 W . .. I y C ALAMIl CllOOWfL, N (v\-v V X ) \ MMC \ VW*\#\£\ u'v^ \i £v °*'. Intensive Inventory Unit Boundary Unit identified as a WSA Portion of Unit found to lack Wilderness characteristics |.V>V\^j Existing National Park or f ■ ''•>. *n .1 Forest Service Wilderness Proposed National Park Service or Forest Service Wilderness •wr mm TTT |Vr >,~% l! 5UMISf I < Ml*t K h / si (llt/f 'HtHMliK .11' I 'i / 0 f«. \ ^6 1/ l\ l; * < A ' * a / r*-. ,.t