ISOTOPE REFERENCE POINTS (FOR ISOTOPE CHRONOSTRATIGRAPHY) IN PALEOZOIC SECTIONS OF THE URALS

Abstract

The isotopic makeup of carbon in marine carbonates exhibits quasiperiodic variations in time. Since these changes were controlled by the global balance of organic and carbonate carbon in the oceans, reliably dated isotope shifts could serve as reference points for high-resolution stratigraphic correlation. Our investigations have demonstrated that a temporal correlation of the δ13C curve with fluctuations in sea level can be identified not only by statistical analysis of a large body of samples, but also in 'pure form,' i.e., in a single, lithologically uniform sequence that is known to contain reliably dateable levels marked by eustatic changes. Further regional investigations aimed at finding isotope markers in reference Paleozoic sections may identify many important paleoceanologic events and thus promote a radical improvement of high-resolution stratigraphic correlation.