Tectonic Erratics - remarkable exotic blocks emplaced by the Henderson thrust, Eureka County, Nevada: a new petroleum exploration target in north-central Nevada

Abstract

Throughout north-central Nevada, Cambrian-Devonian, largely siliciclastic strata of the Roberts Mountains allochthon (RMA) overlie an autochthon of coeval largely carbonate strata. In Eureka County, masses of the carbonate strata also form topographic highs above the RMA, and on the east side of the Roberts Mountains they occur along a post-Antler thrust fault that duplicates the RMA. We propose that the Henderson thrust initially developed along the Roberts Mountains thrust and then ramped upwards and eastwards duplicating the RMA. In the process, carbonate blocks were plucked from the lower plate of the Roberts Mountains thrust and incorporated and transported in the upper plate of the Henderson thrust. Over large areas, the siliciclastic strata of the RMA in the upper plate of the Henderson thrust has been removed by erosion, but the carbonate blocks carried in the upper plate remain as topographic highs structurally overlying the siliciclastic strata of the RMA in the lower plate of the Henderson thrust. Those forming Lone Mountain and Devils Gate are several kilometers long and up to 300 m thick. They bear an analogy to glacial erratics and are termed tectonic erratics. Along a north-south trending belt in Eureka County, both upper and lower plates of the Henderson thrust dip to the east, and the tectonic erratics occur in the base of the upper plate. We propose that these erratics in the subsurface are potential reservoir rocks for oil fields such as the one at Blackburn, Eureka County.

AAPG Datapages/Search and Discovery Article #90193 © 2014 Rocky Mountain Section AAPG Annual Meeting, Denver, Colorado, July 20-22, 2014