Geochemical Constraints on Lithium Transport in Fault and Fracture Systems

Session: Faults, Fractures, and Geomechanics for the Energy Transition

Presenting Author:

Adam Cawood

Authors:

Cawood, Adam J.¹, Ferrill, David A.², Rangel-Landeros, Isaac³, Butler, Kristina L.⁴, Sickmann, Zachary T.⁵, Blake, Madigan⁶, Ibarra, Daniel E.⁷, Swanson, Brandon⁸, Munk, Lee Ann⁹, Boutt, David F.¹⁰, Stockli, Lisa D.¹¹, Stockli, Daniel F.¹², Gagnon, Catherine A.¹³

(1) Southwest Research Institute, San Antonio, TX, USA, (2) Southwest Research Institute, San Antonio, TX, USA, (3) The University of Texas at Dallas, Dallas, TX, USA, (4) University of Texas at Dallas, Dallas, TX, USA, (5) The University of Texas at Dallas, Dallas, TX, USA, (6) The University of Texas at Dallas, Dallas, TX, USA, (7) Brown University, Providence, RI, USA, (8) Albemarle, Silver Peak, NV, USA, (9) University of Alaska Fairbanks, Fairbanks, AK, USA, (10) University of Massachusetts Amherst, Amherst, MA, USA, (11) University of Texas at Austin - Jackson School of Geosciences, Austin, TX, USA, (12) Dept. of Earth and Planetary Sciences, University of Texas at Austin, Austin, TX, USA, (13) Brown University, Providence, RI, USA,

Abstract:

The role of structurally controlled fluid flow pathways is potentially an under-recognized mechanism for lithium sourcing in closed-basin systems. Extensional deformation is known to influence basin formation, sedimentation, and hydrothermal circulation, but its role in lithium transport and mineralization is poorly understood. We present new results from a targeted study of calcite veins and spring deposits in and around Clayton Valley, Nevada, aimed at evaluating the role of faults and fractures in subsurface lithium delivery. We integrate field-based structural analysis with calcite U–Pb geochronology, trace element geochemistry, and stable and clumped isotope analyses to characterize timing, sources, and temperatures of lithium-bearing fluids. Samples include calcite-mineralized normal faults and opening-mode fractures in Precambrian to lower Paleozoic basement rocks and Miocene to Pleistocene volcano-sedimentary basin fill, along with modern travertines and spring deposits.

Lithium concentrations from bulk rock dissolution in calcite veins and travertines range from <2 to 460 ppm, with elevated values interpreted to reflect lithium-rich fluid inclusions. U–Pb calcite ages span ~241–4 Ma, recording a protracted faulting history, with younger mineralization associated with Basin and Range extension and modern basin formation. Clumped isotope temperatures range from ~25°C to 140°C, with normal faults in lower Paleozoic units (including basin-bounding faults) exhibiting the highest temperatures.  Stable isotope data show that vein calcite samples have δ¹⁸O (VPDB) signatures depleted relative to previously analyzed bulk volcano-sedimentary rocks of the Esmeralda Formation, but similar to modern travertine carbonates from Clayton Valley. Vein calcites are depleted in δ¹³C (VPDB) compared to spring deposits and travertines, potentially suggesting a fluid composition for vein calcite closer to a mantle-like end-member. A positive correlation is observed between the reconstructed δ¹⁸O_water (‰ VSMOW) and clumped isotope temperatures,  consistent with mixing between meteoric waters and deeper, rock-buffered fluids. U–Pb calcite ages show a positive correlation with temperature, with older mineralization associated with hotter fluids. This pattern may reflect progressive cooling of the crust during ongoing extension and exhumation.

Our results suggest that long-lived, fault-controlled fluid flow may have played a key role in lithium transport and enrichment in Clayton Valley, potentially including subsurface fluid transport from adjacent areas and basins that contributed additional lithium to the system. Recognizing similar structural controls could improve lithium exploration strategies in other tectonically complex, closed-basin settings.