1. Mass extinction and Ecological turnovers at the Permian-Triassic boundary (PTB): causes and effects. Barash M.S. (P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences) On the Paleozoic-Mesozoic boundary (Permian-Triassic - PTB), 251.0±0.4 Ma, there was the largest mass extinction of organisms: 96% of marine species have died out. The biodiversity was reduced from ~250 000 species to less than 10 000. Mass extinction at PTB boundary Integration of continental plates to the Pangea Anoxia Increased contents of CO 2 Poisoning by H 2 S Global collapse of bioproductivity Fluctuations of a sea level Volcanism Warming as a result вулканизма Warming owing to metane release Short coolings Impact-eventsEtc. Combination of many of these mechanisms All these factors which reduced the biodiversity are substantiated by paleontological, geological, geochemical, isotopic, and other data. Some factors yield visible relations but other relations are absent or unknown. What were the causes of this catastrophe? Formation of the Pangea Anoxia Sea level and stable isotopes at PTB О 18 - warming 13 С – degradation of bioproductivity 87 Sr/ 86 Sr – change of weathering mode at land aridization 34 S – sulfur discharge from the mantle Influence of a climate Warmings: Thawing of continental ices and rise of a sea level and rise of a sea level Increase of ocean circulation – development of an anoxia development of an anoxia Disappearance of upwellings – reduction of productivity reduction of productivityCoolings: Organism habitats disappear, reduce, and move and move Strengthening of circulation – enrichment of water by enrichment of water by oxygen oxygen Increase of productivity These factors can render positive and negative influence on biota development Sea surface temperature at PTB Influence of Volcanism Siberian Trap Province at PTB is effect of the greatest eruption in the Phanerozoic The trap province covers 2 million sq. km. The initial area is ~7 million sq. km, Lava volume – 1-4 million cub. km. Volcanism continued ~1 million years The main conclusions The presence in intervals of sharp changes in biota's development of several abiotic events, the cause-effect relation between which is unknown or expressly absent, gives us grounds to believe that large-scale changes are affected by more general cosmic factors that are outside the limits of the solar system. All the terrestrial processes, the biospheric included, develop in close and continuous relation with the extraterrestrial processes that occur beyond the solar system in the space to which our planet belongs. Influence of methane disintegration Relation between abiotic factors and mass extinction of organisms at the Permian–Triassic boundary *Global darkness because of emission in an atmosphere of a dust and fine detritus, *cooling, * acid rains, *increase in concentration of rare elements, *decrease of photosynthesis, and primary production *disturbance of food chains, *huge tsunami, *gigantic asteroid can cause volcanic eruption. Impact Events Recent Position of the PTB craters and Siberian Trap Province (STP) Crater was created by 55 kilometers wide asteroid Araguainha crater, D~40 km, impactor ~ 2-3 km Crater Bedout, D~180 km, impactor ~10 km Wilkes Land crater