Lithium from Source to Sink: Genesis and Evolution of Li Brines and Clays Active

Science Issue and Relevance

Lithium (Li) is one of the 35 critical mineral resources identified by USGS as necessary to the U.S. economy and national security. Lithium is mined from pegmatites, brines, and clays, but it is the production from brines that dominates international supply. The U.S. has one mine in Nevada that produces lithium from a brine but the output is small in comparison to other, non-U.S. brine resources. With the project demand for lithium and improvements in the extraction technology, lithium-bearing clays could become a larger portion of the U.S. lithium resource portfolio.  The discovery of new resources requires expert knowledge of where lithium resides in the Earth's surface and how it is concentrated.

The Great Basin and surrounding regions contain lithium in rhyolites and ignimbrites, brines, geothermal waters, and surface and deep clays in closed basins. The ignimbrites are "part of a larger ignimbrite province that extends from Idaho thru the Sierra Madre Occidental of western Mexico" (Henry and John, 2013). Lithium brine in Clayton Valley NV has been mined for lithium since 1966 and the lithium clay deposit at the McDermitt caldera on the NV-OR border is the largest single lithium resource in the U.S. (~2 Mt). These lithium-bearing resources are components of our larger, "working" model for the genesis and evolution of lithium brine and clay resources in the western U.S.

Sources/Usage: Public Domain.

Methodology to Address Issue

We will evaluate the Great Basin and surrounding regions for the components of the lithium brine and clay model by tracing the lithium pathway from source to sink, then use this information to improve our estimates of known lithium resources in brines and clays.  Products will be produced in preparation for a future mineral resource assessment for undiscovered lithium resources.

Project tasks will evaluate the following:

• lithium source rocks,
• past drainage basin evolution and climatic conditions over Eocene to Holocene time,
• present surface and groundwater flow,
• geothermal waters and other closed basin brines,
• lithium clays in playa surfaces and basin sediments.

Sources/Usage: Public Domain.

Two additional project tasks will utilize the findings from the other project tasks:

• Test the lithium pathway conceptual model in the Searles Lake System - attempt to construct a mass budget for lithium and tungsten in the Owens River system. The system is appropriate for mass budget calculations because the source of lithium and tungsten is known to be the Long Valley Caldera, and the drainage is constrained to the Owens River system, including the four lakes.
• Development and testing of assessment criteria - organize creation of datasets containing information on lithium content in rocks, sediments, and water in the Great Basin, and the spatial locations and relationships among these reservoirs in preparation for a mineral resource assessment.

Specific study areas include:

• McDermitt Caldera
• Clayton Valley and surrounding basins, including the South Borate Hills, a boron (B) and lithium resource
• Owens River drainage basin including Searles Lake, known to have a lithium-bearing brine
• Lithium and boron deposits in the Mojave Desert
• Salton Sea with lithium-bearing geothermal brines

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