Structural geology and 40Ar-39Ar geochronology of the Goldstone-Lane Mountain area, Mojave Desert, California

摘要

Metasedimentary rocks near Goldstone, California, consist in ascending structural order of (1) a calc-silicate hornfels unit; (2) a quartzite, schist, and radiolarian chert unit; and (3) a calcareous and pelitic sequence of rocks that contains minor basaltic or andesitic composition dikes, sills, and flows(?). Unit 1 is of unknown, but probably pre-Mesozoic age; unit 2 is lower Paleozoic, in part Ordovician, and is correlative to lower Paleozoic eugeoclinal rocks in the El Paso Mountains north of the Garlock fau unit 3 is probably correlative to upper Paleozoic (Permian) basinal sequences in the El Paso Mountains. These rocks were strongly deformed during a progressive deformational event that caused isoclinal to tight folding about northwest-southeast–trending fold axes and northeast-dipping axial planes. Tectonic transport during this deformation was in a southwesterly direction. Similarity of structural trends to those in the El Paso Mountains suggests that the deformation in these two areas is the same age and predates intrusion of Permo-Triassic plutons in the El Paso Mountains.