Project considers critical mineral potential of heavy-mineral sands

Heavy-mineral-sand placer deposits are the world’s primary source for titanium and zirconium. In Wyoming, Cretaceous-age heavy-mineral sands are also a potential source for rare earth elements, hafnium, niobium, and vanadium.

The elements mentioned above are critical mineral commodities, which are essential to the economic and national security of the United States. The U.S. Department of Interior in 2018 created a list of 35 such mineral commodities.

For this project, Wyoming State Geological Survey (WSGS) geologist Derek Lichtner is assessing critical mineral potential of heavy-mineral sand deposits in the Upper Cretaceous Rock Springs Formation in Sweetwater County. His study combines ore-grade analyses and geologic reconstruction.

The goal is to provide geochemical analyses, including bulk rock, trace element, and rare earth element analyses; petrographic analysis of ore mineralogy and provenance; and predictive framework for critical mineral potential in the Rock Springs Formation.

The project could be the first of many for Cretaceous heavy-mineral sand ore deposits in Wyoming. Future work may focus on the Mesaverde Formation in the Bighorn Basin, Fox Hills Sandstone in the Powder River Basin, and Frontier Formation in southwest Wyoming.

Geologist Derek Lichtner examines a dark maroon-colored heavy-mineral sand paleoplacer in the Rock Springs Formation near Bradley Road, southeast of Rock Springs. Unlike most sandstones, which are composed mostly of quartz, these paleoplacer deposits are enriched in dense, dark-colored minerals that contain titanium, zirconium, rare earth elements, and other trace elements. During the late Cretaceous the waves and currents of the Western Interior Seaway concentrated the "heavy" minerals in this ancient beach deposit.

New geologic map postcard available

A new WSGS postcard depicting the general geology of Wyoming is available. The 4-inch-by-6-inch card includes a colorful map of rock formations, faults, basins, mountain ranges, and other geologic features throughout the state.

The geologic map is modified from the Geologic Map of Wyoming, first published in 1985 by J.D. Love and A.C. Christiansen, and shows map units as young as active modern sand dunes to igneous and metamorphic rocks more than 3.4 billion years old. The map explanation points out rock units that are important to Wyoming’s economic geology and also highlights certain units that contain fossils.

The new postcard is available online and at the WSGS office on the University of Wyoming campus in Laramie.

Geologists assess Greater Green River Basin baseline geologic data

The Greater Green River Basin (GGRB) in southwestern Wyoming produced 62 percent of Wyoming natural gas in 2019. That same year, the basin was responsible for 13 percent of the state’s oil. Although nearly all modern production in the region is conventional, the source rocks for these conventional systems, including the Lewis Shale, Hilliard-Baxter-Mancos, Niobrara, and Phosphoria formations, are high-priority petroleum systems that may have potential as continuous reservoirs.

The WSGS is collecting and interpreting baseline geologic data from the Wyoming portion of the Southwestern Wyoming Province petroleum system, or GGRB. This updated assessment includes location, formation top and thickness, initial API gravity, initial production, initial gas/oil ratio, and bottom-hole or maximum recorded temperature from oil and gas wells in the GGRB. Additional useful data collected include gas analyses, total organic carbon, and producing intervals.

The data will be added to the Survey’s spatial subsurface energy database, which incorporates similar datasets derived from other basins across Wyoming, as previously funded by the U.S. Geological Survey National Coal Resources Data System Unconventional Oil and Gas program. This work complements the in-production WSGS digital depth-to-Precambrian basement map by expanding the subsurface dataset from the basement to the surface using data from existing oil and gas wells.

WSGS collaborates with Bureau of Rec on South Granite Mountains Fault system project

The WSGS assisted the U.S. Bureau of Reclamation this summer on an investigation of the South Granite Mountains Fault system in the Seminoe and Ferris mountains. Trenches were excavated to identify and measure recent offset along the fault system. The goal of the multi-year study is to determine the local earthquake hazard of the poorly understood South Granite Mountains Fault System. Two trenches, 70 and 100 meters long, were dug 10 miles apart on the northern flank of the Seminoe Mountains. In addition, a third trench, roughly 50 meters long, was excavated across the Ferris Mountains segment of the South Granite Mountains Fault system, near Pete Creek. Bedrock and unconsolidated materials were found in the trenches, hinting at Quaternary (<2.6 million years) events recorded in the trench. Geologists spent months examining the exposed earth in the trenches, recording unconformities, offsets, fissures, and other evidence of recent surface rupturing earthquakes. Ghost clasts, offset bedding planes, fissure fills, and changes in soil helped tell the area’s geologic story.

Staff spotlight: Jim Stafford

A series recognizing staff and their contributions  Jim Stafford—Project Geohydrologist who focuses on resource analysis, modeling, GIS, and online maps at the WSGS, 15 years of service What do you do at the WSGS: My specialty is acquiring and creating large databases of resource information, processing and organizing it, and using it in spatial and/or temporal models that I create. I use the analytical products of the models to make maps, figures, and graphs showing the results. I conduct hydrologic and geologic research on a variety of topics and work with team members to write and edit reports. Over the last 5 years I have also been using my GIS skills to make and maintain a number of interactive online maps, which are a great dynamic way to display analytical results of our projects. I have a lot of experience with Wyoming geology, and digitize and compile geologic maps some years. What makes your job interesting: Primarily I love science! Always being able to learn new things about the Earth and our state is great. I have always loved maps and I get to spend a lot of time making them. I really enjoy the challenge of solving complex data processing puzzles. The variety of work I do keeps it fun and interesting. How does your job help Wyoming: There is a tremendous amount of raw data out there. I help make it into useful decision-making tools for our state. Every time a road is built or a wind turbine is sited, a geologic map is consulted. When a natural gas play is permitted or a mine is planned, our aquifer reports are used. I get to be part of the team that primes the pump of geologic knowledge, which runs the engine of Wyoming's responsible resource development. What are some of your favorite geologic features in the state: As a life-long Wyomingite, I am very biased! There is something I find fascinating in every part of the state. Having a background in water, I especially like the hydrogeologic oddities like Periodic Spring, Sinks Canyon, Anchor Reservoir, and Devil's Gate. Underrated is maybe the Pathfinder Dam area. It has a lot of neat history and geology, and when the reservoir is overtopping, it's one of the best waterfalls you will ever see.

Director's corner: Wind's role in geologic processes

In Wyoming, the windiest part of the year tends to stretch from late October to mid- April. Rawlins takes the honor of having the highest average wind speed in our state. Laramie and Cheyenne are tied for the second windiest, and Casper comes in at third place. As anyone who lives in Wyoming knows, wind has the power to transport sand and sometimes even gravel. These eolian processes occurred in our geologic past as well as the present. 

Several Paleozoic and Mesozoic rock formations host lithified, ancient sand dunes now exposed as cross beds in sandstone layers. These are particularly visible in Telephone Canyon east of Laramie on I-80, where the Pennsylvanian and Permian Casper Formation preserves sand dunes up to 3 meters high. In much of the rest of the state, Pennsylvanian eolian cross-bedding can be seen in cliffs of the Tensleep Formation, which are particularly well exposed in Wind River Canyon.

Modern sand dunes are prevalent throughout the Wyoming Wind Corridor, an exceptionally windy zone that stretches from the Greater Green River Basin in the west to the Medicine Bow and Shirley mountains in the east. Active dunes can be found in the Killpecker dune field as well as dune fields from Seminoe Reservoir to north of Casper. These active dunes can be stabilized by vegetation or migrate with the wind. Often they have elongate shapes oriented parallel to the prevailing wind direction. 

Wyoming has the proud honor of being the site of the world’s second-largest wind-deflation basin. Big Hollow, west of Laramie, is a valley formed solely by wind erosion, a geologic process that current residents of Big Hollow will probably confirm continues to occur today.

On a smaller scale, rocks lying at the surface can also be affected by the wind. They are abraded, etched, and polished by wind-blown sand until they show a distinctive smooth surface, shallow grooves, and dull shine on the side of the rock facing the wind. These rocks are called ventifacts, and they can be found across the state.    

As autumn comes to an end, and the winds get colder and snow begins to fall, I hope you, too, will appreciate the fascinating geologic effects of wind—from the comfort of your home, of course.

--Dr. Erin Campbell, WSGS Director and  State Geologist

Study assesses critical mineral potential in Kemmerer Coal Field deposits

A new WSGS project kicked off this summer assessing the critical mineral potential of coals in the Kemmerer Coal Field. The goal is to establish a baseline dataset of the trace element geochemistry of samples in order to better understand them as potential hosts of critical and strategic minerals. The project includes characterization of the field’s coals and bounding beds, including underclay, roof rock, and clay-rich partings. Investigations of coals and coal by-products as potential critical mineral sources have become a popular field of study over the past few years, with a particular emphasis on rare earth elements. Recent studies have also shown promising levels of critical mineral enrichment in underclays and partings, not just coals. Scarce critical mineral data for Wyoming coal fields presents an opportunity to evaluate these deposits in-state.

Fieldwork was completed in August, and targeted the Frontier and Adaville formations in Lincoln County. More than 60 samples were collected from local outcrops around Kemmerer and from the Kemmerer Mine. Over the next few months WSGS geologist Kelsey Kehoe and contract geologist Garrett Gay will complete geochemical analyses in cooperation with the University of Wyoming’s Geology Department.

WSGS geologists hope to eventually expand this project in order to create a broader database of baseline trace element data of Wyoming coals.

This WSGS project presents an opportunity to conduct complimentary work alongside the University of Wyoming’s School of Energy Resources, who is working on rare earth element studies of coal and coal products in the Powder River Basin as well as at the Kemmerer Mine.  

Groundwater Atlas of Wyoming is updated

Groundwater is especially important in a state like Wyoming where surface water can be scarce and seasonal.

The WSGS interactive Groundwater Atlas of Wyoming makes it easier to explore basic groundwater data quickly, and was recently updated with new datasets. 

The update greatly expands the groundwater information on the online map and offers a single source for most groundwater data. Learn more about the update in the news release.