GEOCHEMISTRY AND MINERALOGY OF THE UBEHEBE VOLCANIC FIELD, DEATH VALLEY

The Ubehebe Volcanic Field is located in northern Death Valley occupying an area of about 3 km². The area contains at least twelve recognizable volcanic craters that formed through phreatomagmatic eruptions, some of which dissect previously formed cinder and spatter cones. Eruption of the youngest, largest crater (Ubehebe; 700-800 m wide, 235 m deep) blanketed the crater rim and surrounding area (15 km²) with at least 50 layers of basaltic scoria and ash. Recent research has put the timing of the eruptions between 0.8 and 5.1ka and relates them to the local groundwater table. However, while they have been classified as basalts, there has been very little work focused on the geochemical variation of the rocks that make up the volcanic field.

Samples were collected from three craters in the southern cluster. Among our findings are mineralogical and textural differences from crater to crater, including disequilibrium features in orthopyroxene phenocrysts and quartz xenocrysts. Major and trace element analysis of 22 basalt samples is currently underway to determine the complete compositional range, and whether compositional differences exist among these three craters with the goal of understanding the nature of the magma and the geologic processes that operated when this volcanic field was produced.