Tectonic-sedimentary responses of the Tarim Basin, Xinjiang during the late Early Palaeozoic

The Tarim Basin recorded a large-scale spreading-compression-uplifting cycle during the Early Palaeozoic. During the early Early Palaeozoic (Sinian-Middle Ordovician), the basin was in the extensional setting and displayed a palaeogeographic framework composed of a platform (carbonate platform) in the west and a basin (Manjiar-Kuruktag deep-water basin) in the east. There deposited the thick shallow-water platform carbonate rocks represented by the Middle-Upper Cambrian Lower Qiulitag Group and Lower-Middle Ordovician Upper Qiulitag Group in the west-central part, while the pelagic siliceous and limy mudstones in the Manjiar-Kuruktag deep-water basin in the east. The great changes of tectonic background and sedimentary facies and palaeogeography of the basin took place during the middle-late Middle Ordovician. The nearly NS-trending (uplift)-(depression) framework of the basin is well represented by the Central and Northern Tarim uplifts, Tangguzibasi and (Awat)-(Manjiar) depressions. The sedimentary responses are manifested in the disappearance of the carbonate (platforms), influx of the terrigenous clastics and coarsening upwards, appearance of volcanic activity and volcanic clastics, and infilling of thick sandy and muddy turbidites in eastern Tarim Basin. It can be seen that the (Middle)-(Late) Ordovician and Middle Devonian times are believed to be significant for the collapse of the sea area, (uplifting) of the basin, and falling of the relative sea level.