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Current Projects


Mapping

Digital Depth to Precambrian Basement Map of Wyoming

The WSGS is creating a basement map that will provide valuable information about the depth to Precambrian geology of Wyoming. The map will serve as the framework for related WSGS projects focused on constraining Precambrian lithology and geochronologic relationships, as well as provide key data to identify potential areas of critical mineral deposits.

Critical minerals are important to U.S. national security and economy. Wyoming hosts significant occurrences of many of these minerals, in part due to the wide variety of geologic environments present throughout the state. Many critical minerals in Wyoming are either found in, or originate from, Precambrian igneous and metamorphic basement rocks. These rocks are exposed at the surface in many of the basement-cored mountain ranges in the state, but can be buried below Phanerozoic strata in the nearby basins.

The WSGS is compiling and preserving depth-to-basement and structure data from seismic interpretations, cross sections, and well logs. The data will be incorporated into a Geologic Map Schema (GeMS)-compliant geodatabase and utilized to generate a digital, publicly available depth to the Precambrian basement map.

The project is partially funded by the National Geological and Geophysical Data Preservation Program and will be completed in 2022.


Mapping in the Laramie Mountains

Patty Webber

The WSGS is working on multiple integrated mapping projects in the Laramie Range. One of these projects is a study of the central part of the Laramie Range funded by the USGS’s Earth Mapping Resources Initiative (Earth MRI) program. The emphasis of the project is mapping the King Mountain and Ragged Top Mountain 7.5-minute quadrangles in Albany and Laramie counties. These quadrangles are part of the larger central Laramie Range study area.

The Laramie Range contains known but poorly understood rare earth element-enriched alkalic plutons, two anorthosite complexes, a greenstone belt, and a large mafic dike swarm. The anorthosite complexes cumulatively have potential for base- and precious-metal deposits (Cu, Ni, Au, Ag) as well as critical mineral resources (Ti, V, W, Cr, and REEs). Metavolcanic rocks of the Elmers Rock Greenstone Belt are a potential s ource of Ni, Cr, Mo, and PGEs. Additionally, several known occurrences of graphite fall within the focus area, including the Rabbit Creek graphitic schist deposit in Platte County near the northernmost part of the study area.

This two-year project will focus primarily on geologic mapping and geochemical analyses, culminating in the publication of two maps and a geodatabase of geochemical results in summer 2022. This is also a collaborative project with several members of the University of Wyoming’s Department of Geology and Geophysics: Dr. B. Ronald Frost, emeritus professor, who mapped much of the Laramie Range over the past several decades; Dr. Simone Runyon, assistant professor and economic geologist; and Janet Dewey, associate research scientist and analytical geochemist.

The WSGS is also working with Dr. B. Ronald Frost on a series of 1:24,000-scale quadrangle maps in the Laramie Mountains. Three quadrangles—Guide Rock, Poe Mountain, and Moonshine Peak—display key relations between the various plutons of the Laramie anorthosite complex and the Archean basement rocks to the north. The portion of the maps covering the Laramie anorthosite complex include mapping conducted by UW faculty and students in 1980–1996. The mapping of the Laramie anorthosite complex, combined with mapping of the adjacent country rock by George Snyder of the USGS, appeared as the USGS Open-File Reports OFR 84-358 (A–M).

Geologic map of the Guide Rock quadrangle, Albany County, Wyoming (MS-105) is available.

Geologic map of the Poe Mountain quadrangle, Albany and Platte counties, Wyoming (MS-106) is available.

Mineral Investigations

Heavy-Mineral Sands

Heavy-mineral

Heavy-mineral sand placer deposits, sometimes called “black sands,” are the world’s primary source for titanium and zirconium, as well as a potential source for hafnium, niobium, vanadium, and the rare earth elements. These elements are considered by the USGS to be “critical minerals,” which are essential to the economic and national security of the United States.

A “heavy mineral” is an accessory detrital mineral with high density relative to quartz and feldspar, the two most common minerals in sands and sandstones. Because of their high density, heavy minerals are subject to mechanical sorting during transport in rivers and along shorelines. A placer deposit can form if the sorting process produces a significant accumulation of concentrated heavy minerals. In Wyoming, such deposits are found as paleoplacers (fossil placers) in various rock formations, including the Cambrian Flathead Sandstone, Cretaceous Mesaverde Group, and in some Precambrian and Eocene rocks.

In an effort to better characterize the chemistry and mineralogy of these deposits, the WSGS is working on two projects of different scope and focus. The goal of the first project is to thoroughly sample and analyze the geochemistry and mineralogy of several heavy-mineral sandstones in the Upper Cretaceous Rock Springs Formation, of the Mesaverde Group, in Sweetwater County. The second project is broader in scope, involving heavy-mineral sand deposits of all ages throughout Wyoming. For this statewide project, the main goal is to conduct preliminary sampling and analysis of the heavy-mineral sand deposits for which data are scarce or nonexistent, as well as to augment older datasets with modern analytical methods, with a focus on the rare earth elements.

Heavy-mineral sandstone in the Upper Cretaceous Rock Springs Formation, Richards Gap, Wyoming (OFR 2021-6) is available.

Coal

Kemmerer Coal

Geologists are assessing the critical mineral potential of coals in the Kemmerer Coal Field in southwestern Wyoming. The goal of the project is to establish a baseline dataset of the trace element geochemistry of samples to better understand them as potential hosts of critical and strategic minerals.

Fieldwork will target the Frontier and Adaville formations in Lincoln County. Geologists will collect samples from local outcrops around Kemmerer and from the Kemmerer Mine for geochemical analyses.

The long-term goal is to expand this project in order to create a broader database of baseline trace element data of Wyoming coals.

Trace element geochemistry of coal deposits in the Adaville and Frontier formations, Kemmerer coal field, Wyoming (OFR2022-1) is available.

Water

Groundwater Response in Sandstones of Wasatch and Fort Union Formations, Powder River Basin

This project update uses groundwater monitoring well data from the Bureau of Land Management to examine how groundwater levels in sandstone aquifers of the Wasatch and Fort Union formations have responded to decreased coalbed methane (CBM) production in the Powder River Basin, Wyoming. The type, magnitude, and timing of water level responses will be evaluated as they relate to the depth of the monitored sandstone aquifer and its vertical distance from a CBM-producing coal seam. An analysis of the data will attempt to construct mathematical models to predict the time required for groundwater levels to return to preproduction depths. The report will contain monitoring well and water level statistics as well as time series graphs for all monitoring sites.

Groundwater level recovery in the sandstones of the Lower Tertiary aquifer system of the Powder River Basin, Wyoming (RI-78) is available.

Groundwater Salinity in the Wind River and Bighorn Basins

The WSGS is continuing its study of groundwater salinity in the state’s energy-producing basins, the new project focusing on the Wind River and Bighorn structural basins of northern Wyoming. This will be the fourth such report; the previous publications examined groundwater salinity in the Greater Green River, Powder River, and Denver-Julesburg basins. A statewide report has also been published.

Groundwater is an important and precious resource in Wyoming where quality varies greatly throughout the geologic basin. One way to measure the quality of water is its salinity. “Salinity,” or total dissolved solids, is the amount of dissolved material that remains as residue after the liquid portion of a water sample evaporates. The Wyoming Department of Environmental Quality uses salinity to determine if groundwater resources are suited for human consumption or agriculture. In Wyoming, saline groundwater is encountered most frequently as a byproduct of oil and gas exploration in deep basin aquifers.