TESTING THE DEVELOPMENT OF δ13C GRADIENTS ACROSS A PROXIMAL TO DISTAL TRANSECT OF AN ORDOVICIAN-SILURIAN CARBONATE SHELF IN CENTRAL NEVADA
During the Early Silurian, normal faulting or large-scale slope failure resulted in the transformation of the carbonate shelf geometry from a shallow ramp to a rimmed platform. This transition may have resulted in a shift from open ocean circulation on the shelf to a more restricted ocean circulation system. In many modern carbonate platforms isotopic gradients of dissolved inorganic carbon (DIC) develop as local carbon cycling occurs in restricted near shore settings, altering the δ13C compared to open ocean settings. In an attempt to examine whether similar processes were recorded in the geochemistry of Paleozoic carbonate strata, we tested the development of δ13C gradients across a paleogeographic transect of an Ordovician-Silurian carbonate shelf in response to the change in basin geometry. The evolution of the carbonate shelf during the Early Silurian helps identify the effects of restricted ocean circulation on a Paleozoic inorganic carbon isotope record.