CARBONATE FACIES CHANGES FROM THE LATE PERMIAN TO THE EARLY TRIASSIC FOR THREE NEW LOCALITIES IN THE NANPANJIANG BASIN, SOUTH CHINA

The Permian-Triassic mass extinction is considered to be the largest extinction event in Earth’s history with 95% of marine species and 70% of terrestrial vertebrates becoming extinct as a result. The cause for this extinction is heavily debated with hypotheses ranging from increased volcanism resulting in ocean acidification to a meteor impact event. The Nanpanjiang Basin in southern China provides a stratigraphically conformable record of the P-T boundary from which we can study changes in the fossil record as well as changing oceanic conditions.

Here we present data from the Heshan and Bana formations from the Tian’e platform in the Nanpanjiang Basin. These sections span the Permian carbonates, the altered zone as well as the Triassic microbialites. Microscopic and macroscopic analysis of: 1) fossil diversity, 2) species richness, 3) diagenetic structures, as well as 4) isotope signatures will contribute to the understanding of the environmental changes during the Late Permian to the Early Triassic. Data collected thus far show a trend from species rich packstone to mudstone, to microbial framestone from the Permian to the Triassic. There is a high diversity of fossils in the packstone including foraminifera, ostracodes, crinoids, gastropods, bryozoan, fusilinids and algal remains, while the mudstone contains only a small number of foraminifera, algal remains, and peloids, the microbialite also had gastropods, fusilinids and forminifera fossils in the upper part of the section. A comparison of these microbialites directly above the extinction boundary from three localities on drowned platforms in the Nanpanjiang Basin will shed light on the environmental conditions of the early Triassic post extinction environment.