Lower Cambrian bioherms in central Nevada and eastern California

Xiaoping Zhou, University of Nevada, Las Vegas


A comparative sedimentological and paleontological study was made of two approximately coeval Lower Cambrian bioherm complexes, one in the Ravenswood area of Lander County in central Nevada, and the other in the Montenegro Member of the Campito Formation in the White-Inyo Range of eastern California. Although both bioherm complexes were constructed by archaeocyaths and calcareous microbial organisms, there are significant differences in the structure and fabric of the biohermal limestones, in the taxa and diversity of archaeocyaths, and in the diversity of the bioherm community in general. The Ravenswood bioherms developed as framework reefs in a high-energy, normal marine setting and display a relatively high diversity of archaeocyaths and associated organisms, as well as distinct core and flank facies. The Montenegro bioherm complex developed in a restricted, low-energy setting as a mud mound composed of lenticular units (kalyptrae); it contains a lower diversity archaeocyathan fauna and a depauperate fauna of other organisms.