DETAILED GEOLOGIC MAPS OF THE LANE MOUNTAIN AREA, NORTH CENTRAL MOJAVE DESERT, CALIFORNIA, PART 2: STRATIGRAPHY AND STRUCTURE

Detailed mapping of the Lane Mountain area (1:6000 scale) north of Barstow CA, allows resolution of complex stratigraphy and structure of enigmatic metasedimentary rocks. Paleozoic and Mesozoic (?) strata comprise five blocks that can be correlated. Most contacts are west verging bedding plane faults. The SW and SE blocks expose >30,000 feet (tectonic thickness) of east dipping tectonically juxtaposed Paleozoic strata. Structurally lowest meta-andesite, is overlain by quartzite and argillite of basinal affinity, overlain by mixed siliciclastic and carbonate off shore deposits, and shallow water miogeoclinal carbonate strata of late Paleozoic age, tectonically overlain by meta-andesite, turbidites (quartzite, metasiltstone), other deepwater sediments (metachert, argillite), overlain by off shore deposits of mixed siliclastic, calc silicate and impure carbonate strata.

The same strata are exposed in other blocks, but are more deformed, folded, attenuated and or with thousands of feet of strata missing. Correlation with the Central and NE blocks demonstrates up to 15,000 feet of strata are missing. Rocks in the Central block are highly folded and metamorphosed. Paleozoic rocks in the NE and NW blocks include the same tectonically juxtaposed strata, but are more tightly folded and attenuated than exposures to the south. Allochthonous rocks resembling miogeoclinal Paleozoic carbonates of the Cambrian Bonanza King Formation, Mississippian Monte Cristo Limestone, and Pennsylvanian Bird Spring Formation, may have been emplaced as backslides onto the tectonically juxtaposed deeper water strata are present in the Central and SW blocks. Black chert conglomerate/breccia may be Mississippian overlap sequence, or emplaced as submarine slide onto older deeper water sediments in the SW block. Exposed in the Central block, distinctive conglomerate and calc silicate hornfels strongly resembles Jurassic Fairview Valley Formation. McCulloh (1960) recovered a Mesozoic age fossil from these rocks. The new mapping indicates Paleozoic rocks in the Lane Mountain area can be correlated with Paleozoic rocks in the Northwest Mojave Terrane within the context of the prevailing regional tectonostratigraphic framework.