Oscillations of a fluvial?lacustrine system and its ecological response prior to the <scp>end?Triassic</scp> : Evidence from the eastern Tethys region

The end-Triassic mass extinction is considered one of the “Big Five” events in Phanerozoic. However, whether terrestrial ecosystem began to deteriorate or even collapse prior Triassic–Jurassic (Tr-J) transition remains controversial. Compared with documented data from western Tethyan region, evidence eastern realm limited. We undertake a fitting analysis sedimentary system, floral community successions and major geological Xujiahe Formation as reflected by Qilixia Section, Xuanhan area, northeast Sichuan Basin, China. Our results reveal an oscillating fluvial-lacustrine depositional system during Late Triassic, dominant processes mainly controlled Indosinian Movement. Beside influence on Flora, climate changes played more important role. Fluctuating conditions cooler dryer climates at this time promoted diversification gymnosperms under overall warm humid setting Triassic area. Superimposed long-term state, destabilization occurred over 1 million years Tr–J interval study possibly response intensified storm wildfire activity following environmental changes. Although Flora always recovered interruption tectonic movement, it ultimately collapsed extreme climatic ecological pressures induced Central Atlantic Magmatic Province event.