Paper No. 6
Presentation Time: 11:55 AM
COMPARATIVE SEQUENCE AND EVENT STRATIGRAPHY OF LOWER SILURIAN STRATA OF THE APPALACHIAN BASIN AND GOTLAND, SWEDEN: TEMPLATE FOR HIGH-RESOLUTION GLOBAL CORRELATION
Preliminary analysis suggests that isochronous Lower Silurian (lower Wenlock) strata deposited during the Ireviken Isotope Excursion in Gotland, Sweden and the Niagara region of New York and Ontario contain strikingly similar stratigraphic architectures. Both stratigraphic intervals are dominated by a cyclic alternation between clean carbonates and more argillaceous carbonates interbedded with shales, but the similarities go beyond lithology. The sections also contain faunal event beds (epiboles), an abundance of patch reefs, and biofacies changes that appear to be coordinated. Centimeter-scale comparison of these heterolithic stratigraphic intervals has the possibility to generate one of the most high-resolution intercontinental correlations yet suggested in the geologic literature, with implications for answering one of the most long- lived debates in sedimentary geology: are sedimentary cycles within foreland basins the signature of global or regional phenomena? Lower Silurian strata of the Niagara region and Gotland were deposited at different paleolatitudes and under different tectonic regimes. These two areas may have been separated by as much as 4000 kilometers, spanning 10 to 15 degrees latitude, during the early Silurian. The varying tectonic stress fields of these two basins make it all the more astonishing that they contain such remarkable similarities. Thus, a strong extrabasinal influence such as eustasy is the favored interpretation for cycle genesis.