A well-justified stratigraphical correlation of continental successions and new palaeogeographic reconstruction of Pangaea reveal new insights into the northern Pangaean climate development influenced by palaeogeography, palaeotopography, glacio-eustatic sealevel changes and ocean currents. The overall Permo-Carboniferous aridization trend was interrupted by five wet phases. These are linked to the Gondwana icecap. The aridization and weakening of wet phases over time were not only caused by the drift of northern Pangaea to the arid climatic belt, but also by the successive closure of the Rheic Ocean, which caused the expansion of arid/semi-arid environments in the Lower/Middle Permian. The end of the Gondwana glaciation rearranged ocean circulation, leading to a cold, coast-parallel ocean current west of northern Pangaea, blocking moisture coming with westerly winds. The maximum of aridity was reached during the Roadian/Wordian. The Trans-Pangaean Mountain Belt was non-existent. Its single diachronous parts never exceeded an average elevation of 2000 m. The maximum elevation shifted during time from east to west. The Hercynian orogen never acted as an orographic east-west barrier, and the Inter-Tropical Convergence Zone was widely displaced, causing four seasons (dry summer/winter, wet spring/autumn) at the equator and a strong monsoon system.

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Environmental context. What caused the biggest known mass extinction on Earth ~252 million years ago? A possible killer mechanism was the release of specific gases into the atmosphere, which eventually led to destruction of the ozone layer. This is now supported by new laboratory experiments in which ozone-destructing gases were generated when heating rocks from East Siberia (Russia) – reconstructing what happened naturally in Siberia during explosive gas eruptions 252 million years ago. Abstract. What triggered the largest know mass extinction at the Permian–Triassic boundary 252 million years ago, when 95% of the species in the oceans disappeared? New geological data suggest that eruptions of carbon (CH4, CO2) and halocarbon (CH3Cl and CH3Br) gases from the vast sedimentary basins of east Siberia could have triggered a period with global warming (5°–10°C) and terrestrial mass extinction. The gases were generated during contact metamorphism of sedimentary rocks around 1200°C hot igneous intrusions. One of the suggested end-Permian extinction mechanisms is the extreme ultraviolet radiation (UV-B) caused by a prolonged destruction of stratospheric ozone induced by the emitted halocarbons. This hypothesis is supported by a new set of experiments, where natural rock salt samples from Siberia were heated to 275°C. Among the gases generated during heating are methyl chloride (CH3Cl) and methyl bromide (CH3Br). These findings open up new possibilities for investigating ancient environmental crises.

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Three supercontinents have been suggested to have existed in the last 1 Gyr. The supercontinent status of Pangaea and Rodinia is undisputed. In contrast, there is ongoing controversy on whether Pannotia existed at all. Here, we test the hypothesis of a Pannotian supercontinent. Using first-order tectonic constraints, we reconstruct the Paleozoic kinematics of major continents relative to the East European Craton. Back-rotation from Pangaea results in a supercontinent constellation in the early Paleozoic corroborating the existence of Pannotia. The presented model explains first-order constraints for both the break-up of Pannotia and the subsequent assembly of Pangaea. The break-up of Pannotia comprises (1) the early Paleozoic opening of Iapetus II and in turn the Rheic Ocean, concomitant with the subduction of the Neoproterozoic Iapetus I Ocean and (2) the coeval opening of the Palaeo-Arctic Ocean, which separated Siberia from the North American Craton. The subsequent convergence of the North American Craton, Avalonia, Gondwana and Siberia with the East European Craton resulted in Paleozoic collisional orogenies at different plate boundary zones. The existence of Rodinia, Pannotia and Pangaea as pari passu supercontinents implicates two complete supercontinent cycles from Rodinia to Pannotia and from Pannotia to Pangaea in the Neoproterozoic and the Paleozoic, respectively.

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