Stratigraphy and structural geology of the Roberts Mountains allochthon, Dee and Rossi properties, northern Carlin trend, Nevada.

摘要

Detailed biostratigraphy of the Roberts Mountains allochthon in the northern Carlin trend is used to produce a new geologic model for the area. Stratigraphy was reconstructed and geologic maps were revised. Radiolarians and graptolites provided age control allowing for the reconstruction of a new composite stratigraphic column. Identified strata include the upper Vinini Formation, the Cherry Spring chert, the Elder Sandstone and the Slaven Chert. Application of the reconstructed stratigraphic column to map revisions revealed a structural fabric dominated by contraction-related strain. Intra-plate stratigraphy and structural style define three major thrust sheets in the Dee-Rossi area and confirm the presence of major bounding structures. These thrust sheets are shown to extend outside the Dee-Rossi area and are laterally continuous for at least 16 kilometers. Four distinct episodes of deformation are differentiated; one based on the presence of syn-orogenic strata and three based on fold style and geometry.