There is evidence for an enormous elliptical Impact Crater with the dimensions of 1270x950 km on the ocean floor of the Arctic Ocean. This elliptical impact crater and the dynamic effects of the ejected material have formed the deep sea basin area below -3000 m in the Arctic Ocean and triggered an expansion tectonics process. This impact crater seems to be responsible for the Permian-Triassic boundary ~253 million years ago, which has caused the biggest mass extinction in Earth’s history. The Permian-Triassic (PT)-Impact Crater was formed by an oblique impact. This means that the impactor, an asteroid or comet in the diameter range of probably 60 to 200 km, collided with our planet at a very shallow angle, of probably less than 8°, with a relative low impact velocity of around 8 km/s and a resulting impact pressure of probably <5 GPa for most (> 90%) of the excavated and ejected material, which makes it difficult to provide mineralogical evidence (shock metamorphism) to proof this global impact scenario. A computer simulation shows a close correlation between the topography of the assumed P/T-Impact Crater and the topography of a simulated elliptical impact crater that was created under similar conditions. The PT-Impact Event caused a gigantic butter-fly-shaped ejecta blanket which covered the majority of the northern- and southern hemisphere. Within the boundaries of this ejecta blanket many large secondary impact craters were formed by the ejecta, with crater diameters of up to 450 km. Please also read Part 2 & 3 of my hypothesis, where I describe many of the secondary impact-craters and -structures in more detail, which were caused by the PT-Impact Event. I have found mineralogical proof for six real PT-secondary-craters. In Europe up to 20 large secondary craters were caused. In India a secondary impactor produced a 450x380km elliptical crater which formed the Bay of Bengal. Similar large secondary craters were caused along the NE-coast and on the NW-coast of Australia and in South-America. And in Africa four extensive impact crater chains were caused. The impulse of the PT-impact and the impulses of the PT-ejecta and -secondary-crater-impacts, caused a global fracture pattern on Earth’s crust that was the trigger for a global expansion-tectonic-process which is still going on today. The ocean-floor age map and the ocean-floor topographic map provide evidence for this expansion tectonic process.