SEQUENCE STRATIGRAPHY AND PALEOKARST EVOLUTION OF THE ORDOVICIAN ANTELOPE VALLEY LIMESTONE NEAR BEATTY, NV

The mid-Ordovician Antelope Valley Limestone of southwestern Nevada contains an abundance of peculiar dolostone breccias that have been interpreted throughout southern Nevada and east-central California as the result of paleokarstification (Cooper and Keller, 2001). The breccias appear within conduit-like cavities ranging in width from centimeters to meters and are centimeters to tens of meters high. Repeated vertical facies successions, each capped by paleokarst, are indicative of transgressive-regressive eustatic cycles. The breccias of the Ordovician Antelope Valley Limestone will be closely examined in the field and in thin section in order to (1) test the hypothesis that the breccias are of paleokarst origin; (2) determine the evolution of paleokarst development found within parasequences; (3) create a sequence-stratigraphic framework for the study area that will enhance the resolution of the relative sea-level history of the Cordilleran margin of Laurentia; and (4) further refine the paleogeographic/paleotectonic model for the Cordilleran margin of Laurentia during the Lower to Middle Ordovician of Cooper and Keller (2001). Collectively, these paleokarst breccias testify to the complex history of the early Paleozoic Cordilleran margin of Laurentia.