DEFORMATION OF THE MINERAL HILL ERRATIC ALONG THE HENDERSON THRUST, EUREKA COUNTY, NEVADA

In the mountain ranges of north-central Nevada, there are two widespread but very different packages of coeval rocks structurally juxtaposed by the extensive low-angle Roberts Mountains thrust. The lower plate is composed of several thousand meters of relatively undeformed autochthonous, largely carbonate strata, deposited in the epicontinental sea that flooded western North America from Cambrian to Devonian time. The upper plate, the Roberts Mountains allochthon (RMA), is an equally thick package but is severely deformed and is largely siliciclastic. It was deposited from Cambrian to Devonian time on the continental rise and ocean floor adjacent to the western continental margin. During the Late Devonian – Early Mississippian Antler Orogeny, the deep water siliciclastic strata was emplaced upon the autochthonous carbonate succession.

Surprisingly, in the Roberts Mountains region, there are many large masses of the autochthonous carbonate succesion that form topographic highs above great thicknesses of the siliciclastic strata of the RMA. A recent model proposes a previously unrecognized post-Antler thrust, the Henderson thrust, plucked carbonate blocks from the lower autochthon and transported them on top of great thicknesses of the RMA (Finney et al., 2015). Aside from being mapped throughout the Roberts Mountains region, the Henderson thrust extends in a north-south trend to the east. Mineral Hill, located 35 km northeast of the Roberts Mountains, is located along the Henderson thrust. The research herein tests the Henderson thrust model by mapping carbonate masses in Mineral Hill in search for kinematic indicators of thrusting like those previously mapped throughout the Roberts Mountains region. Discovering these carbonate masses holds significant implications for geologic mapping of north-central Nevada and economic exploration in the region.