Paleobiogeographic Analysis of the Assemblages of Late Vendian Macrofossils

Resumo

Similarity analysis of the taxonomic composition of the 13 major localities for Vendian macrofossils worldwide is performed using the Ochiai coefficient. There are two distinct subgroups among shallow-marine localities. The first subgroup includes Australia, the southeastern White Sea area, Podolia, India, and the Urals (degree of similarity 0.16–0.38). The second subgroup includes localities of Siberia, Northwest Canada, South China, South America, Southern Namibia, and the United States (degree of similarity up to 0.58). Such a division of the shallow-marine localities corresponds to the distribution of carbonate sediments and of the tubular problematic species Cloudina. This division is probably climate-related; i.e., localities of the second subgroup are associated with warm-water conditions (precipitation of carbonates, distribution of problematic remains with a carbonate skeleton), while the localities of the first subgroup are associated with cold-water conditions. Thus, the analysis performed indicates the location of the Australia, Baltica, and India cratons at high latitudes (which differs from the results demonstrated in some paleotectonic reconstructions based on paleomagnetic studies) and confirms the hypothesis that the Siberian Platform was located at tropical and subtropical latitudes. Accordingly, two paleobiogeographic realms are identified for the Late Vendian: the Subpolar Realm (Australia, Baltica, and India) and the Equatorial Realm (Siberia, Laurentia, Kalahari, South China, and Rio de la Plata).