Early Paleozoic Tarim Orocline: Insights from paleogeography and tectonic evolution in the Tarim Basin

摘要

The Tarim Basin, situated between the Paleo-Asian tectonic domain and the Proto-Tethys tectonic domain, has undergone a complex tectonic evolutionary process under various geodynamic conditions and has provided abundant information about the dynamic evolution of the peripheral orogens. From the Sinian to Early Ordovician, the Tarim-Qaidam Block was under a regional extensional setting. A carbonate platform developed widely in the basin, flanked by a passive continental margin setting. As the extension enhanced, the spreading of the Proto-Tethys Ocean was accompanied by subduction and collision, which resulted in a nearly linear subduction zone. Since the Late Cambrian, a continuous oblique subduction and induced sinistral shearing produced an initial bending of the Proto-Tethys subduction zone, leading to rotation and bend of the original Tarim-Qaidam Block and internal long striped subaqueous paleo-uplift. During the Middle and Late Ordovician, the Altyn-Qilian Orogen underwent continent-continent collision and continental crust deep subduction. The buckling of the subduction system enhanced under the sinistral transpressional field, resulted in the bending of the Altyn-Qilian Orogen to an S-shape. The subaqueous uplift areas in the basin were further elevated, rotated, and eroded to show an S-shape distribution and an unconformity developed between the Silurian sediments and underlying strata. The extent of the carbonate platform decreased, around which developed a high-energy facies in a platform margin and formed important oil-gas reservoirs. In the Silurian to Middle Devonian, the Tarim Basin evolved into a two uplifts with a depression framework under the dual-directional compressional field. Near the end of the Late Devonian, the S-shape distribution pattern of paleo-uplifts was covered by the Upper Devonian and Carboniferous sequence in an angular unconformity. Moreover, the planar distribution of thrust faults with strike-slip property around the paleo-upli