Gold Prospectors Association of America Presentation 2017
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The document provides a detailed overview of Wyoming's geologic history and associated mineral deposits from the Archean Eon to present day. It describes how Wyoming's landscape has evolved over time through tectonic plate interactions, mountain building events, and changing sea levels. These geological processes emplaced various mineral deposits in the state, including chromium, platinum, and gold in Archean rocks. Younger formations from the Paleozoic through Cenozoic eras contain fossils, petrified wood, agates, jade, and uranium deposits that were uncovered through erosion. Wyoming's complex geological past shaped the distribution and types of valuable mineral resources found across the state today.
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Gold Prospectors Association of America Presentation 2017
- 1. GEOLOGIC HISTORY OF WYOMING WITH AN EMPHASIS ON MINERALS MIKE BINGLE-DAVIS AND MARRON BINGLE-DAVIS 1
- 2. INTRODUCTION • Emplacement Basics • Wyoming Geologic History – Settings – Deposits POWDER RIVER BASIN BIGHORN BASIN WIND RIVER BASIN GREATER GREEN RIVER BASIN DENVER- JULESBURG BASIN HANNA BASIN 2
- 3. MINERAL AND DEPOSIT BASICS • Mountain building (orogeny) • Volcanic bodies – Dikes, Sills, Laccoliths, Stocks, Porphyries – Metamorphism • Erosional deposits – Placer 3
- 4. MOUNTAIN BUILDING • Plate interaction • Crustal melting • Upwelling magma • Magma cooling • Mineral emplacement • Eventual erosion and secondary emplacement 4
- 5. VOLCANIC BODIES • Dikes • Sills • Laccoliths • Stocks • All are upwelling of magma that result in mineral rich materials being brought close to surface • Difference is in speeds and cooling 5
- 6. LACCOLITHS 6
- 7. PORPHYRY • Magma cools in 2 phases • First is deep in crust and creates larger crystals • Second magma is cooled more quickly and at shallower depths 7
- 8. PEGMATITES • Coarse, igneous deposits • Different cooling rates • Pockets of magma • Erratic in location, structure and content • Are classified as zoned or unzoned 8 UNZONED ZONED
- 9. WYOMING GEOLOGICAL HISTORY • Continental movements • Sea level changes • Different exposures • Associated minerals • Mining and localities 9
- 10. ARCHEAN OF WYOMING (4.0 to 2.5 Billion yrs ago) • Exposed in cores of mountain ranges • Oldest rocks in Wyoming are 3.07 Ga from the Beartooth Mountains (could be as old as 3.3 Ga) • Best exposures in Wind River Range • Important economic minerals include chromium, platinum, nickel, iron, and gold – Gold is typically in quartz veins and shear zones in the greenstone belts 10South Pass Gold in Quartz Vein
- 11. 11 4 Ga 2.5 GaAt the beginning of the Archean, land masses were isolated and unstable By the end of the Archean, land masses had converged and became a stable place for sedimentation and tectonics
- 12. 12 2.5-4.0 Ga 1.6-2.5 Ga 540 Ma- 2.5 Ga 540 Ma- 1.6 Ga Casper Douglas Wright Newcastle Rawlins Laramie Cheyenne Rock Springs Riverton Jackson Gillette Sheridan Cody ARCHEAN EXPOSURES IN WYOMING
- 13. ARCHEAN FACTOIDS • Atmosphere: ~11% CO2/0% O2 to ~4% CO2/0% O2 – Early life was anaeorbic and ocean bound • Iron from volcanoes precipitated into Banded Iron Formations (BIFs) – Found in Seminoe Mts and as stream gravels • First evidence of life (Stromatolites) – Found in Medicine Bow Mts 13
- 14. CASPER MOUNTAIN CHROMIUM DEPOSIT • Discovered in 1911 • Surface trenching completed • Open pit mining proposed but never completed • Contained in bands or lenses 14
- 15. CENTENNIAL RIDGE PLATINUM • Post 1890 mining • 1923 sulfides were assayed and reported to carry platinum • Created a small boom 15
- 16. PALEOPROTEROZOIC OF WYOMING (2.5 to 1.6 Billion yrs ago) • Exposed along margins of Archean rocks – Best preserved in Medicine Bow Mts • Two groups - meta-sedimentary (includes glacial) and meta-igneous – Somewhere between 2.5 and 1.7 Ga • Lots of Iron, some Copper and Gold, and Uranium in the metased rocks – Much of Black Hills gold is of this age – In fault and shear zones within the sed rocks– many are northeast trending 16
- 17. 17 2.1-1.8 Ga WY Paleogeography of this time period is highly debated because it is reconstructed by matching up like provinces in isolated exposures
- 18. 1818 2.5-4.0 Ga 1.6-2.5 Ga 540 Ma- 2.5 Ga 540 Ma- 1.6 Ga Casper Douglas Wright Newcastle Rawlins Laramie Cheyenne Rock Springs Riverton Jackson Gillette Sheridan Cody PALEOPROTEROZOIC EXPOSURES IN WYOMING
- 19. PALEOPROTEROZOIC FACTOIDS • ~2.4 Ga is “Great Oxidation Event” – Anaerobic organisms die • Huronian Ice Age – Snowball Earth • BIFs more common as aerobic organisms start to proliferate • Recognizable continents form at 2.5 Ga • 2.5 Ga = 0% O2/4.2% CO2; 2.3 Ga = 0.7% O2/1.3% CO2 – Photosynthesis • 1.6 Ga = ozone layer forming and eukaryotes evolving 19
- 20. IRON DEPOSITS NEAR LANDER • Main formation is dense, hard laminated quartz, magnetite, and amphibole • Layers range in thickness from 1mm to 6cm 20
- 21. SUNLIGHT MINING DISTRICT – WEST OF CODY • Vein mineralization • Alteration zones in intrusive stocks • Mining completed following these intrusions 21
- 22. MESO- AND NEOPROTEROZOIC (1.6 BILLION TO 540 MILLION YRS AGO) • Western edge of Rockies was edge of the continent 1.6 Ga • Three major sedimentary sequences in region – later metamorphosed and intruded by granites – Major deposits absent from Wyoming • Pegmatites of 1.4 Ga important for minerals like Beryl, Garnet, and Spodumene (source of lithium) 22
- 23. 23 1 Ga-750 Ma WY First known supercontinent – Rodinia – creates connection of habitats that sparks evolution and allows major mountain building – by the end of the Proterozoic, Rodinia starts to break-up, which sets up next evolutionary boom in Cambrian
- 24. 540 Ma- 1.6 Ga 540 Ma- 2.5 Ga 242424 2.5-4.0 Ga 1.6-2.5 Ga Casper Douglas Wright Newcastle Rawlins Laramie Cheyenne Rock Springs Riverton Jackson Gillette Sheridan Cody MESO- AND NEOPROTEROZOIC EXPOSURES
- 25. MESO- AND NEOPROTEROZOIC FACTOIDS • Rodinia supercontinent • First major mountain building event – Grenville Orogeny • Atmosphere: 1% O2/0.66% CO2 to 10% O2/0.23% CO2 • Evolution of multicellular organisms – First green algae - ~1.2 Ga – Ediacaran fauna – 630-540 Ma – primitive plants, soft-bodied animals, small shelly fauna, trace fossils… lots of ? 25
- 26. CASPER MOUNTAIN PEGMATITE • Pegmatite emplacement • Ultramafic magma intrusion • Reported serpentine (asbestos), chromite schist, feldspar, copper, beryl, REE, and reports of gold 26
- 27. COPPER MOUNTAIN PEGMATITE, WYOMING • Tapolite (below), tourmaline, beryl, etc. • Similar to Casper Mountain 27
- 28. PRECAMBRIAN GEMSTONES 28 Sapphire Schist, Palmer Canyon Ruby Schist, Wind River Mts Aquamarine, Anderson Ridge area Diamond, Granite Mts Iolite, Palmer Canyon Jade, Granite Mts
- 29. PENNSYLVANIAN (300 MA) • A time of drying after massive sea level high – Paleozoic not known for its minerals • Casper Formation – Known for its thick red sandstones and limestones – Jasper and agates are common in the limey beds and will weather out and may be found as float in stream sediments 29
- 30. 30 Jasper and agates found in the Casper Formation mainly along the flanks of the Bighorn Basin
- 31. JURASSIC (150 MA) • Morrison Formation – Lots of Jurassic dinosaurs including big sauropods and Allosaurus, pterosaurs, crocodiles, turtles, fish, very early mammals, and shells – Fossils known for being silicified (agatized) 31
- 32. Near Kaycee, WY32 Dinsosaur bones can be very colorful due to complete replacement by silica Como Bluff (near Medicine Bow) is one of the most famous Jurassic dinosaur sites
- 33. UPPER CRETACEOUS (100-65 MA) • Lance Formation – Holds a diverse array of dinosaur and other fossils including T-rex, Triceratops, Edmontasaurus, early mammals, turtles, lizards, shells, and plants • Laramide Orogeny begins – Most Precambrian exposures from this 33
- 34. 34 Some of the most spectacular dinosaur fossils come from Wyoming
- 35. PALEOGENE (65-23 MA) • Fort Union Formation (Paleocene) – Petrified wood and other fossils • Wasatch/Bridger/Wind River formations (Eocene) – Opal, jade, petrified wood/stumps, agates, Turritella agate, Green River fish, Uranium • White River Formation (Oligocene) – Opal, Uranium, and lots of fossils 35
- 36. Petrified Wood, Sweetwater Cty Jade, Wind River Fm, Granite Mts Slater Agate, near Guernsey Green River Fm Opal, White River Fm Turritella Agate, Wasatch Fm, Red Desert
- 37. 37 NEOGENE (~20 MA) • Split Rock Formation • Sandstones, conglomerates, mudstones, limestones, and tuffs of Miocene age • Known for its Sweetwater agates 37
- 38. 38 Sweetwater agates are common throughout this time period and will fluoresce under ultraviolet light due to the presence of hydrous Uranium
- 39. PRESENT DAY - SUMMARY • During Precambrian, Earth was volatile with volcanic activity and instability – When most rocks containing economic minerals and ores were deposited – Rocks later folded, faulted, metamorphosed allowing for mineral emplacement • Paleozoic/Mesozoic marked by massive sea level changes – Jaspers/agates – Dinosaur and other fossils • Laramide Orogeny turned Wyoming into a mountain state exposing PreC rocks and its minerals • Post K-Pg boundary known for its agates with some opals 39
Editor's Notes
- Hello and thank you for inviting us to the Rocky Mountain Landman Institute. When my wife, Marron was approached she initially asked me if she should accept, I said absolutely and that if possible, I would like to speak as well. Here we are, given the task of presenting to you the Petroleum History of Wyoming With the age of the Earth estimated at 4.5 billion years – this means, with a talk length Of 50 minutes, leaving time for questions, we only have to cover 90 million years per Minute, so we should get started.
- Today we will be focusing on the petroleum history of Wyoming and thankfully you all Should have a copy of the talk in your handouts – there is a lot of material We will be discussing some basics of petroleum geology, the formations that host The petroleum, and some examples from around Wyoming This slide illustrates the five major basins where a person can find petroleum as well As the geologic time scale, with the formations that contain the petroleum. Rather quickly, we will begin with the oldest know petroleum deposition and move Towards the present day. While we do this, we will be bouncing between the different basins, so feel free to Follow along on your map
- Morrison is a temporary return to nonmarine – vast sand dunes and floodplains Generally mudstones with the various sand that produces
- One of the more noticeable outcrops, has some of the most famous dinosaur deposits I always pictured it to be like the Great Lakes sand dunes
- The height of the Western Interior Seaway, again the coastline goes back and forth slightly Responsible for not only some of the biggest producers in the state but also the main source rocks for the at least the Cretaceous if not the rest of the Mesozoic and Cenozoic Most of the horizontal activity is in these formations
- Western Interior Seaway all but gone – return to vast floodplains and nonmarine conditions but tropical – imagine palm trees in Wyoming This time is known for coal formation, which includes CBM Fort Union does produce some oil but only in SW Wyoming
- Imagine the Amazon, big rivers in a tropical landscape, with huge coal swamps associated Crocodiles and other more tropical animals were common Almost half of the country’s coal comes from PRB – estimated 170 billion short tons of coal exists in PRB with only 6% recoverable (10 billion short tons)
- We have known there was oil in our state since the 1830s with the first sales being that collected from natural oil seeps and sold as wagon grease Since the first well was drilled, we have continued our pursuit of oil and gas 2015 permits – almost 7000 261 wells spudded in 2015; 214 were horizontal