Tectonic and paleogeographic evolution during closure of the Paleo-Asian Ocean and their effects on biosphere

The tectono-paleogeographic processes that operated during the closing of the Paleo-Asian Ocean had a significant influence on the biosphere but poorly understood.The Zhesi Formation, which formed during the middle Permian, consists of marine facies strata, whereas the Linxi Formation, which accumulated in the late Permian, comprises terrestrial facies sediments, indicating a coeval marine-to-terrestrial transition. The biosphere evolution was strongly affected by this tectonics process. During the middle Permian, the movement of the Xilinhot Block from the southern Paleo-Tethys Ocean to the northern Paleo-Asian Ocean broke up the magmatic arcs that existed in the region between the two systems. This enabled the flow of a warm current from the Paleo-Tethys Ocean into the Paleo-Asian Ocean, causing an increase in the sea water temperature and the extinction of cold-water-acclimatized brachiopod fauna at middle Permian. During the late Permian, the amalgamation of the Central Asian Orogenic Belt and North China Craton led to the mixing of the Angara and Cathaysia realms, which previously isolated by Paleo-Asian Ocean to the north and south, respectively. Successfully mixing of the two species motivated by tectonic processes of i) The continuously southward accretion of the Central Asian Orogenic Belt during Paleozoic has significantly extended the habitat of the Angara flora from a high-latitude cold region to a mid-latitude warm region; ii) the northward movement of the North China Craton from tropics and subtropics regions near equator to a mid-latitude warm region has adapted the Cathaysia flora to gradually colder conditions; These two tectonic processes together forced originally distinct temperature acclimatized species evolved convergently through time. Finally, the amalgamation of the Central Asian Orogenic Belt and North China Craton was following a “soft collision” model that did not produce large mountains and Palaeogeographic barriers, which enabled the mixing of the Angara and Cathaysia floras.