HOWLEY, ROBYN A., University of Nevada Las Vegas, Dept. of Geoscience, Las Vegas, NV

ABSTRACT: Cyclic Carbonate Sedimentation in the Middle to Early Late Cambrian, Highland Peak Formation, Southern Nevada: Implications for Interpreting Eustasy

Relative changes in sea level are caused by global events such as changes in ice volume, crustal movement and in rates of sea floor spreading, as well as by local tectonic andor autocyclic events. These relative changes in sea level appear in the stratigraphic record as a hierarchy of cycles with varying stacking patterns. The accuracy with which cyclic carbonate strata record global sea level fluctuations and the methods for resolving depositional causal mechanisms have been questioned.

Proposed is a detailed study and multi-method analysis of Middle to early Late Cambrian peritidal cycles in the 1400-m-thick Highland Peak Formation, Panaca, Nevada. Cycle stratigraphy will be used to (1) resolve causal mechanisms of cyclic carbonates on a broad shallow-water platform, (2) refine the Middle to early Late Cambrian sea level record, and (3) determine the relative position of the Panaca succession on the carbonate platform. Analysis of cyclic strata will combine five methods that previously were used independently or in limited combinations: (1) lithofacies, (2) cycle-architecture, (3) cycle stacking, (4) fischer plots, and (5) spectral analysis. ¹³C and ⁸⁷Sr/⁸⁶Sr secular curves will be established for the Highland Peak Formation and will provide a high-resolution chronostratigraphy for correlation with other Middle Cambrian successions.

The research conducted in this study can be used as a predictive model of carbonate platform deposition and response to low amplitude sea-level events andor tectonism during greenhouse times and will advance our understanding of high-resolution sedimentary processes on shallow-water platforms.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid