Stratigraphy, Sedimentology, and Tidal Processes of the Late Miocene to Early Pliocene Southern Bouse Formation, Southeast Palo Verde Mountains, California

Abstract

Contrasting hypotheses for the depositional paleoenvironments of the late Miocene to early Pliocene southern Bouse Formation currently hinder progress toward a consensus on tectonic and paleogeographic reconstructions for the lower Colorado River region. The basal carbonate member of the southern Bouse Formation has been interpreted to record deposition in either (i) a large inland lake isolated from the ocean, or (ii) a transgressive intertidal to subtidal marine seaway. In this study, we analyze sedimentary lithofacies, facies associations, paleocurrents, and architecture of large-scale compound bedforms to develop a comprehensive depositional model. Our paleocurrent data and analyses of bedform architecture and facies association support a tidal origin for the southern Bouse Formation. Our paleogeographic reconstruction constrains the location of marine connection required by paleontological and sedimentary data. Our interpretation provides strong evidence in favor of a tidal origin and requires post-Miocene regional uplift.