EVOLUTION OF THE PRIMARY PRODUCTIVITY ACROSS DEEP WATER PTB IN SOUTH CHINA

The Permian-Triassic crisis was a major turning point in geological history. Most records of the collapse are not from the pelagic sediments, but from shallow-marine and terrestrial sediments. Although several pelagic sections that across the Permian-Triassic Boundary have been found in Japan. These sections are often discontinuous because of small faults. Fortunately we found a continuous well-preserved faunas (radiolarian, ammonite) section Dongpan section in south China. Integration of algae, geochemical, radiolarian fauna, and mineral data provides new insights regarding the change of paleo-productivity, across the Permian-Triassic Boundary in south China.

Both the Sixs and Baxs can indicate the productivity in the ocean surface. The profiles of biotic Ba and Si show the same trend at bed 2-6 and bed 9-14, but the Baxs is increase from bed 7 to 8, Sixs decrease during the stratum. From the bed 7 to 9 (about 1 meter, equal bed 24 e in Meishan Section about a few centimeters.) the Baxs and algae are high but the Sixs and radiolarian are low, it imply that the evolution of ocean surface ecology is very different; for the silica biology are extinct. However the algae biology (proxies by Baxs and algae) are increase.

The primary productivity of the deep water section in South China is very different from the Meishan Section. The event bed (equal the Bed 24e in Meishan Section) is very thick (about 1 meter). During this stratum the biotic Si is decrease. However, the Baxs and algae are increase. The 2-MHP index is the minima at 24e in Meishan Section imply the minima cyanbacterial. Our study indicates that across the PTB the extinction of the phytoplankton communities is partly. Not all kind of producers are extinct. Across the first episode of extinction the cyanbacterial and fauna like radiolarian, condont, foraminifer and ostracods, are vanish first and algae are affected little by the change environment.