FRONTIERS IN CHRONOSTRATIGRAPHY: A PROGRESS REPORT FROM THE EARLY PALEOZOIC

Deciphering Earth history requires a properly ordered chronology. While regional correlation of time-specific features (e.g., discontinuity surfaces) may be relatively straightforward along depositional strike, traversing depositional dip remains fraught with difficulties that often prevent resolution of competing correlation hypotheses. Yet, these steep lateral facies gradients contribute many paleoenvironmental parameters that are central to paleontological, oceanographic and climatic models. Miscorrelation, therefore, can have a multiplicative effect, significantly skewing our understanding of Earth history and natural resources.

Today, an array of tools is available to researchers for use in chronostratigraphic studies, but their applicability and interpretation remains uncertain. Early Paleozoic strata of the midcontinent provide a natural laboratory to test the utility of these new correlation tools. We've tested the reproducibility and diagenetic alteration of C-isotopes at local to intercontinental scales in rocks ranging from pristine limestones to dolostones and low-carbonate siliciclastics. This ongoing work demonstrates that C-isotope stratigraphy is one of the most robust and informative of chronostratigraphic tools, and its accuracy and utility is greatly enhanced when coupled with facies analysis (e.g., mapping of unconformity surfaces), biostratigraphy, and tephrochronology integrated within a sequence stratigraphic framework.

While the quest for high-confidence chronostratigraphic correlation may at first glance appear esoteric, application of these new tools in basin analysis and global stratigraphic correlations is already yeilding exciting new paradigms. It is our view, that careful integrative compilation, utilizing C-isotope stratigraphy as a chronostratigraphic foundation, provides enormous gains toward accurately reassembling the scattered, but not lost, pages of Earth history.