The Mesozoic to Cenozoic Exhumation History of the White Mountains, California, USA

Abstract

Development of the North American Cordillera is largely characterized by periods of arc magmatism and deformation associated with subduction of the Farallon slab. The Sierra Nevada batholith is the type-locality of the magmatic arc exposed in southern California. However, it remains unclear how deformation caused by subduction processes impacted the magmatic arc. To understand the influence of slab traction on arc plutons we applied geo- and thermochronology to Inyo Pluton, White Mountains, California in order to establish constraints on crystallization, deformation, and exhumation. The White Mountains are an eastern constituent of the Sierra Nevada batholith from which we collected 7 samples for titanite triple-dating. The elevation profile consisted of six samples from the White Mountain Shear Zone (WMSZ) and one from the Inyo Pluton. Concordant titanite U-Pb data suggests a Late Jurassic emplacement age associated with delamination of the continental lithosphere. Titanite U-Pb discordia arrays from the WMSZ data and one titanite-fission track age yield Late Cretaceous ages of ~90 Ma which we interpret to represent shear zone deformation associated with initial flattening of the Farallon slab. Titanite fission-track and titanite (U-Th)/He yielded Late Cretaceous – Oligocene ages, suggesting a second period of exhumation which temporally overlaps with the main phase of thick-skinned deformation in the Laramide. The titanite fission-track ages reveal an inverse age-elevation trend which we interpret to represent varying levels of erosion below the detachment fault. Based on these data we suggest that magmatic arcs are impacted by deformation associated with slab dynamics.