Abstract
Miocene lacustrine rocks exposed in the White Basin, north of Lake Mead, comprise limestones, marls, evaporites, tuffs, and siliciclastic facies of the Lovell Wash Member of the Horse Spring Formation. Evaporitic facies have been the source of borate minerals here since at least the early 20th century and lithium enrichment in the Lovell Wash Member has been noted since the USGS studied the area in the 1970's. With moves toward sustainable energy sources and needs for battery storage, this area could become an important U.S. source of lithium. Indeed, over the past year, numerous claims have been made in the White Basin, new roads (dirt tracks) have been constructed, and exploratory drilling has begun in at least two locations. This activity is occurring on lands managed by the Bureau of Land Management just east of the Muddy Mountains Wilderness Area. For more than 20 years, our team has conducted considerable primary geological research in this area, including studies on the textural and geochemical signatures of microbialites, limestones and other rocks that form under the influence of microbial metabolic processes. Microbialites are currently the target of the Mars Curiosity Rover, as well as future Mars missions to recover rock samples from the Red Planet. Our understanding of the Martian rocks, if found, will be greatly-enhanced by our understanding of similar rocks on Earth, like those in the White Basin. One stratum within the Lovell Wash Member contains one of the most diverse and laterally continuous examples of microbially-influenced sedimentation anywhere in the world. This 1-5 meter-thick interval can be traced for over 6 km (3.7 miles) laterally, making it a truly rare feature. One 0.12 ha (0.6 acres) locality, in particular, contains evidence of ancient spring activity and the microbialite diversity associated with these springs. Current mining activities are occurring within 150 m of this important locality and we have already discerned negative impacts on other microbialite units nearby, although we cannot determine if mining or other (tourist, ATV, etc.) activities damaged these features. We fully support lithium extraction in this area, but we would like to encourage the BLM to be aware of these important trace fossil localities and to assist in their protection as mining activities move forward.