Geology of the Oquirrh Mountains, Utah by Edwin W. Tooker Open-File Report OF 99-571 1999 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Menlo Park, CA, CONTENTS Page Abstract 7 Introduction 11 Purpose of the report 11 Location, geomorphic features, and access 13 Acknowledgments 15 Geologic setting of north-central Utah 17 Precambrian basement terrane and the Uinta trend 17 Paleozoic depositional basins 20 Jurassic orogeny 22 Cretaceous Sevier orogeny 23 Formation of the Cenozoic Basin and Range province 24 Tertiary igneous activity and ore deposits 25 Uplift in the Oquirrh Mountains along the Uinta trend during the period of igneous activity 26 Quaternary uplift and Pleistocene glaciation 27 Recognition of nappes in the Oquirrh Mountains . 27 Location of the Oquirrh Mountains nappes . 28 Hinterland source of the nappes 29 Movement of the nappes 29 Convergence of nappes in the area of the future Oquirrh Mountains 30 Stratigraphic features of the main nappes 31 Pass Canyon nappe 32 Bingham nappe 33 Rogers Canyon nappe 34 Significance of variations in nappe sedimentary rocks 35 Structural features of nappes 35 Main and secondary folds 36 Faults 37 Sole and imbricate thrusts 37 Tanscurrent or tear faults 38 Tensional and other normal faults of thrust origin 39 Basin and Range normal faults 39 Igneous rocks associated with the nappes 40 Geology, correlation, and economic importance of typical nappe rocks in the Oquirrh Mountains 41 Pass Canyon nappe 42 Stratigraphic characteristics and correlation of sedimentary rocks 44 Dry Fork unit of looker and Roberts (1988) 45 Flood Canyon unit of looker and Roberts (1988) 46 __ _ _ _ _ _ _________ - _ - __ - ___ __ _ _ ____ _____________ ___ _ ______ ___ A*7__j. i AQ "~ ~" "~ T"O _ _ _ _ .____ _ _ .__ _____ ________ _ .__ __ _________________ __ ____ AQ*-|-^7 Location and types of igneous intrusive and extrusive rocks 51 Associated mineral resources 52 Barneys Canyon and Melco mines 52 Construction materials 53 rnIlCllll QTTI nlldL/UC C-T^T^-t* _____ _...-..-..-..-..-. - .................. -.-_.-_.--.-_.-_.-_.--- ------------------- ._, __--_-_-_-_--_-_--_-----..................... ^j^j^.A Stratigraphic characteristics and correlation of sedimentary rocks 55 Lower Paleozoic formations 55 Manning Canyon Shale. 59 Upper Paleozoic formations 59 Correlation with nappes in adjoining ranges composed of the Oquirrh Group sedimentary rocks 61 f O1QS. Location and types of intrusive and extrusive rocks 70 Bingham mining district area 70 Middle Canyon-Soldier Creek areas 71 Lion Hill and Porphyry Knob areas 72 Ophir-Mercur mining district areas 72 Associated mineral resources 73 Bingham mining district 74 Mercur mining district 74 Ophir mining district. 75 Production from the Bingham, Mercur, and Ophir mining districts 75 Industrial minerals and construction materials 75 Rogers Canyon nappe 76 Stratigraphic characteristics and correlation of sedimentary rocks 76 Lower Paleozoic Green Ravine Formations 77 Oquirrh Group (Upper Paleozoic) formations. 78 Grandeur Member of the Park City Formation (Permian) 80 Structural features 80 Folds 81 Faults 82 Proposed formation of Rogers Canyon nappe structures 83 Location and types of igneous rocks 85 Associated mineral resources 85 South Mountain nappe 86 Stratigraphic characteristics and correlation of sedimentary rocks 87 Rush Lake unit of looker and Roberts (1988) 88 Salvation unit of looker and Roberts (1988) 88 South Peak unit of looker and Roberts (1988) 89 Quaternary deposits 89 Regional correlations of formational units 90 Structural features 92 Folds-------------- 92 Faults 93 Location and types of igneous rocks 95 Associated mineral resources 96 Fivemile Pass nappe 97 Stratigraphic characteristics and correlation of sedimentary rocks 98 Mercur limestone member, Great Blue Limestone 98 Manning Canyon Shale 99 Structural features 99 Folds----------------- 99 Faults 100 Location and types of igneous rocks 100 Associated mineral resources 101 References cited 102 f\lAPPFNDTY i i-a iJ-^lvV ________ ____ - ___________ 111^ U 1. Columnar section showing the lithology of Permian sedimentary rocks by Welsh and James (1961) 113 2. Measured sections of (A) the South Peak, (B) Salvation, and (C) Rush Lake formational units of Tooker and Roberts (1988) that constitute the Oquirrh Group sedimentary rocks in the South Mountain --- - __ » _». -_ - _ _ - . ____________ ,__ __ iz*177 / 1. Location of the Oquirrh Mountains, its 7 1/2-minute topographic quadrangles, and the main mining districts in the range. 127 2. North-central Utah locations of the Oquirrh Mountains, the Basin and Range and Rocky Mountains physiographic provinces, and the inferred axial trace of the Uinta trend 128 3. Inferred locations of the Paleozoic miogeoclinal deposition basins on the craton platform, the North American craton and Antler erogenic belt sediment source areas, and the inferred directions of nappe movement to their foreland depositional sites. 129 4. Generalized columnar sections correlating Paleozoic formations in foreland nappes in the Oquirrh and neighboring ranges . - - 1 30 5. Location of the Sevier foreland and basement promontory along the axis of the Uinta trend. 131 6 Diagram showing the inferred directions and sequence of Sevier-age nappe movements in the Oquirrh Mountains. 132 7. Map showing the locations of the Pass Canyon, Bingham, Rogers Canyon, South Mountain, and Fivemile Pass nappes in the Oquirrh Mountain 133 8. Generalized geologic map of the Pass Canyon nappe 1 34 9. Generalized geologic map of the Bingham nappe. 135 10. Generalized columnar section showing the lithology of the Lower and Upper Paleozoic formations in 1 1 Generalized map showing the distribution of igneous rocks in the Pass Canyon, Bingham, and South Mountain nappes in the central Oquirrh and South Mountains, Utah. 137 12. Generalized map showing the distribution of igneous rocks in the Bingham nappe, southern Oquirrh iviuiiiiumid)TVTrMint^iTic Tv Tt^iH uni _-.__.. _ __-____-___«__..-____________ __-___ ___« ._ ________..___..__.___..___ _ £1 JQ^S 13. Generalized geologic map of the Rogers Canyon nappe. 139 14. Generalized geologic map of the South Mountain nappe. 140 15. Comparison of columnar sections of common-age parts of the South Mountain and Bingham nappes. 141 16. Generalized geologic map of the Fivemile Pass nappe. 142 TABLES ________________________________________________________ 143 1. Igneous rock occurrences in the Oquirrh Mountain nappes 143 2. Lithology of Lower Paleozoic formations in the Bingham nappe 144 3. Lithology of Upper Paleozoic formations in the Bingham nappe 146 4. Production of base and precious metals in the Bingham, Mercur, Stockton, and Ophir mining districts in the Bingham and South Mountain nappes 147 5. Lithology of formations in the Rogers Canyon nappe. - - 148 6. Lithology of formations in the South Mountain nappe. 150 GEOLOGY OF THE OQUIRRH MOUNTAINS, UTAH by EDWIN W. TOOKER Abstract The Oquirrh Mountains are located in north-central Utah, immediately south of the Great Salt Lake, in the easternmost part of the Basin and Range physiographic province. The range consists of northerly-trending aligned peaks 56 kilometers long flanked on the west by Tooele and Rush Valleys and on the east by Jordan and Cedar Valleys. The range hosts several of the more prominent base- and precious-metal and disseminated-gold mining areas in the western United States. The 130-year old Bingham porphyry copper mining district, which is of world-class magnitude in the central part of the range, is still active. The Mercur mining district, which has recently become inactive, was one of the first of the new-type disseminated gold deposits; the Ophir and Stockton base- and precious-metal mining districts are inactive at present. The newest active mining areas in the range are the Barneys Canyon and adjoining Melco disseminated gold deposits, considered to be part of the Bingham mining district by the operator. The Oquirrh Mountains and its flanks also contain a number of industrial mineral resources useful in the infrastructure construction and the smelting industries. Here-to-fore, much information about these mining areas is scattered in numerous publications and has not been placed in a current geologic framework that permits construction of a unified regional deposit model of use in further exploration in the range and elsewhere. This report summarizes regional geologic data as a basis for added resource perspective, identifies as yet unresolved controversial geological interpretations, and is a platform on which to frame future geologic research and exploration. A geologic map of the range (Tooker and Roberts, 1998) is available at a scale of 1:50,000 . The present stratigraphic and structural regime, and the siting of the mineral deposits in the Oquirrh Mountains are the result of a long geologic history. An underlying Precambrian craton consists of a Proterozoic terrane believed to be accreted onto an Archean terrane along a basement suture zone called the Uinta trend. This zone is recognized by its Paleozoic stratigraphic features, evidence of intermittent local structural uplift and erosion, and an alignment of Tertiary intrusives and spatially related ore deposits. 7 Paleozoic sedimentary rocks were deposited in westernmost Utah and eastern Nevada on an irregular, broad, gradually-, and differentially-subsiding, shallowly- submerged craton shelf athwart the Uinta trend zone. Debris shed into two basins separated by the trend, the Oquirrh on the south and Sublette on the north, was from the craton to the east, the Antler orogenic zone on the west, and locally uplifted parts of the trend itself. The composition of the miogeoclinal sedimentary rocks varied during time as well as along the shelf, depending on the relative contributions of source sediments and structural events along the Uinta trend.