The Wyoming State Geological Survey (WSGS) published three new maps under its StateMap program in Carbon and Fremont counties. Two of the maps depict bedrock geology, structure and energy resources, while the third examines surficial geology and Quaternary-age faulting.
All three were mapped at a 1:24,000 scale and are available as free downloads:
- Preliminary surficial geologic map of the Muddy Gap area (Open File Report 2017-4, Carbon and Fremont counties)
- Preliminary bedrock geologic map of the Fort Steele quadrangle (Open File Report 2017-5, Carbon County)
- Preliminary bedrock geologic map of the Bridger Pass quadrangle (Open File Report 2017-6, Carbon County)
“This has been a productive and successful field season for the Wyoming State Geological Survey, and I am proud to say that the work was completed on time, under budget and most important of all, safely,” says WSGS director, Tom Drean.
Several WSGS geologists and contractors spent more than a combined 2,000 hours in the field in 2016 and 2017 completing the mapping projects. Data collected in the field were integrated with satellite imagery interpretation and previous mapping and descriptions. There was on-the-ground examination of rock units and compilation of previously published and unpublished maps and reports.
The Muddy Gap area map includes portions of six 7.5’ quadrangles in northwestern Carbon and southeastern Fremont counties. “Surficial deposits ranging from bedrock outcrop to alluvium exist across the map,” says Seth Wittke, principal investigator of the Muddy Gap project.
The map also contains the Muddy Gap segment of the South Granite Mountains fault system. “The trace of the Muddy Gap segment was further constrained and additional lineaments, which may be fault related, were identified through the course of this project,” Wittke adds.
Investigation of the Fort Steele quadrangle provided information about the depositional history of the Mesaverde Group. A subsurface type log was created for the area, which has oil and gas development potential, and serves as an outcrop analog for these same reservoir rocks in the nearby subsurface.
“This map area hosts a complex set of Mesaverde Group outcrops that are folded and faulted to form the Fort Steele Breaks, Saint Marys Ridge and Cedar Ridge,” explains Fort Steele project principal investigator, Dr. Ranie Lynds. “The potential for additional mineral resources other than hydrocarbons and aggregate gravels along the North Platte River is low.”
Similar to Fort Steele, the Bridger Pass quadrangle produced a type log that will be valuable for nearby energy development. Also, coal quality in the Almond Formation, a locally significant coal source, was determined. Total organic carbon was analyzed from the Niobrara Formation that will provide information for future unconventional oil and gas resource development.
“The goal of this study was to further understanding of Cretaceous stratigraphy in the Atlantic Rim area where future development of coal and coalbed resources is anticipated,” says Jacob Carnes, co-author of the Bridger Pass project. “Comprehensive delineation of this region’s stratigraphy and structure may facilitate not only current oil and gas production but also identify areas for potential development. New and updated geologic maps may also provide a base for further exploration of other mineral resources, including uranium.”
The three maps are accompanied by written reports covering the geologic setting and structure of the quadrangles.
The WSGS received funding for the mapping projects through the U.S. National Cooperative Geologic Mapping Program managed by the U.S. Geological Survey.
Geologic mapping is a critical focus area for the WSGS, which has participated in the StateMap Program (historically CoGeomap) for more than 30 years. With the completion of this year’s projects, the WSGS has produced 28 geologic maps at 1:24,000 scale and 75 geologic maps at 1:100,000 scale as part of the program.
New StateMap projects under development and scheduled to be released in the spring of 2018 are preliminary bedrock geologic maps (1:24,000 scale) of the Gas Hills quadrangle (Fremont and Natrona counties), Albany quadrangle (Albany County), Foxpark quadrangle (Albany County) and Woods Landing quadrangle (Albany County).
For more information about WSGS geology mapping, including available maps, visit the agency’s website.
Below is a map of the three areas recently mapped by the WSGS as part of its StateMap Program (image created by the WSGS).