Paleozoic Cratonal/Miogeoclinal Stratigraphy in the Western Mojave Desert

MARTIN, MARK W., and J. D. WALKER, University of Kansas, Lawrence, KS

Detailed mapping of metasedimentary rocks by many workers in the western Mojave Desert, California, has revealed Paleozoic lithologies of cratonal/miogeoclinal affinity. These exposures are metamorphosed, highly strained, and dismembered, and sit as roof pendants to Mesozoic and Tertiary intrusive rocks. In most outcrops no diagnostic fossils are preserved. Age correlation of these units is based, therefore, solely on similarities to lithologic packages outside the region. Despite the complex tectonic history this area has suffered since the late Paleozoic, the exposures in the western Mojave Desert indicate that Paleozoic paleogeographic elements trend southwest into the region from where they are last clearly defined near the California-Nevada border.

Dolomitic and calcitic marbles, quartzites, and biotite schists make up a major part of the stratigraphy in many areas. The stratigraphy and lithology of these units strongly suggest that they are correlative with late Precambrian-Cambrian units in the Death Valley region. Possible Ordovician and Devonian marbles also are present within some sections; at least one locality contains stromatoporoids of probable Devonian age. Calcite marbles tentatively correlated with lithologically similar Permian units in the Death Valley area are also represented and appear to be depositionally overlain by Mesozoic(?) shallow-marine and arc-derived clastic rocks.

Although the western Mojave Desert region has experienced compressional, transcurrent, and extensional deformation since late Paleozoic, our current understanding and restoration of this deformation history does not significantly alter the general southwest Paleozoic paleogeographic trends known to exist farther east.

AAPG Search and Discovery Article #91009©1991 AAPG-SEPM-SEG-SPWLA Pacific Section Annual Meeting, Bakersfield, California, March 6-8, 1991 (2009)