Petrography and environmental significance of travertine mounds in Keane Wonder Mine, Death Valley National Park

Abstract

Spring-associated carbonate deposits that outcrop across much of the Great Basin are relicts of the region's wetter past and geomicrobiological archives of once-thriving aquatic ecosystems. Ancient travertine deposits from Keane Wonder Spring (KWST) in Death Valley National Park (DVNP) were analyzed for petrological indicators of past changes in surface water flow throughout the groundwater system. Lithofacies analyses of proximal, intermediate, and distal sections along the travertine complex were generated. The surface-exposed proximal site is dominated by aquatic plant calcification including evidence for silicification. The intermediate site represents valuable stratigraphic facies but the channel exposure resulted in extensive post-depositional alteration. Core analyses of the distal site reveal the most promising preservation potential including well-laminated textures for future geochemical analyses. Infrared Stimulated Luminesce (IRSL) dating analyses indicate a preliminary age of KWST to be ~140 ka, consistent with deposition during marine isotope stage 6 (MIS 6). Despite evidence of diagenesis at sites 1 and 2, coupled SEM-EDS and petrographic analyses reveal mineralogic controls on the preservation potential of distinct microfacies and similar work should be considered in future travertine investigations to resolve their potential as paleoenvironmental indicators.