A geologic investigation of Death Valley California

Abstract

Death Valley, California has a rich geologic history and a landscape shaped by diverse tectonic and volcanic activities. Modern-day Death Valley is the product of extensional tectonism, rhyolitic volcanism, and basin development during Miocene basin and range extension. Fault scarps, turtleback faults, alluvial fans, eolian processes, and weathering can be observed in an environment which lacks vegetation making this an ideal locale to study geologic relationships. The most reent Miocene extensional basin and range tectonics have produced a series of normal faults which shaped the horst and graben features observed on the floor of Death Valley.Extensive Miocene volcanism produced widespread pyroclastic sheets which dominate most of Death Valley. To gain insight on magmatic partitioning a detailed geochemical investigation was conducted on a compound cooling unit of the Miocene (ca. 9 Ma) Resting Springs Tuff, east of Shoshone, California. The sequence included a basal vitrophyre, slightly welded rhyolitic tuff, strongly welded rhyolitic tuff, rhyolitic tuff, and welded rhyolitic tuff. Major and trace element geochemical stratigraphy analyses were conducted using X-ray fluorescence to assess elemental partitioning during pyroclastic transport.