9419141 Myrow The relationship between intervals of faunal turnover, including major extinctions, and various depositional and tectonic processes which may ultimately govern these events, is critical to the holistic understanding of the stratigraphic record. Integration of sedimentological, paleontological, and stratigraphic data from all regions in an onshore-offshore profile are required for a complete analysis of system dynamics. The Cambro-Ordovician boundary interval, which records several faunal turnover events including a major extinction at the base of the Cordylodus proavis conodont zone, is generally unrecognized or not preserved in inner detrital belt deposits in North America because of poor biostratigraphic resolution. Sedimentological and biostratigraphic data from well-documented Cambro-Ordovician platform and offshore areas of the Great Basin and elsewhere have been used to propose processes-response models for faunal extinctions, which in many cases include puported ecstatic "events". Unfortunately, little or no information exists from coeval proximal carnal deposits concerning the relationship of intervals of faunal turnover with depositional and tectonic events, which can be used as a test of the cause of extinctions or the global correlation of proposed ecstatic events. Well-exposed and thick Cambro-Ordovician siliciclastic and carbonate carnal rocks in central and western Colorado provide an excellent opportunity to assess spatial and temporal changes in depositional systems during and between faunal turnover events for this poorly understood and biostratigraphically unconstrained paleogeographic region in the Cambro-Ordovician of ancient North America. A two-year project is proposed for a sedimentological and stratigraphic study in which the recognition of unconformitites using conodont biostratigraphy and sedimentological criteria will for the first time enable construction of a detailed sequence-stratigraphic framework for the Cambro-Ordovician of Colorado. Co mparison of systems dynamics for these deposits with well-documented outboard successions will contribute to a more complete understanding of the interplay between the evolution of faunal communities and depositional systems.
