Science Center Objects

Project objectives were to improve the understanding of critical mineral enrichment in black shales and improve accuracy of resource assessments.

schematic depositional model black shales

Schematic of proposed depositional model for black shales of Bakken Formation. Figure 9 from Scott and others, 2017, doi:10.1016/j.chemgeo.2017.01.026.

(Public domain.)

Science Issue and Relevance

Black shales have been of increasing interest in recent years due to their oil and gas potential, but also because many are enriched in nonfuel "unconventional" critical elements such as cobalt, chromium, molybdenum, nickel, platinum group elements, rhenium, and vanadium. Critical metals residing in shales presented a challenge to economic recovery, and thus, development of deposits was "shelved" because metals could not be recovered by traditional methods. With recent advances in metals extraction, it may be feasible to mine these deposits.

Methodology to Address Issue

Re-assessing the potential for critical elements in shales is important and timely because of new analytical techniques and advances in extraction technology. The USGS is in a prime position to conduct a modern assessment of such deposits in the U.S. This requires compiling geologic, sedimentologic, geochemical, and isotopic data already available and collecting new data in selected areas. Project objectives were to improve the understanding of critical mineral enrichment in black shales and improve accuracy of resource assessments. The project consisted of three main tasks:

  • Database development (to include age, host rock composition, tectonic/geologic setting, total organic carbon, rock evaluation, and other inorganic and organic chemical components;
  • Identification of black shale-hosted critical element deposits in the U.S. (initial focus on the Heath Formation metalliferous oil shales in Montana); and
  • Evaluation of processes that form metal-enriched black shale deposits.

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