Neoproterozoic basin evolution of the northern Tarim craton from back-arc rift to passive continental margin: Implications for the opening of the South Tianshan Ocean

Abstract

The Neoproterozoic strata in the northern Tarim craton holds valuable tectono-sedimentary insights regarding the opening time and mechanisms of the South Tianshan Ocean, as well as the tectonic reconstruction of the Tarim craton during the breakup of Rodinia. However, debates remain around the Cryogenian–Ediacaran proto-basin type and evolution, as well as the lack of regional geological correlation at a basin scale. In this study, we employed seismic, drilling and outcrop data to conduct a combined tectono-stratigraphic and sedimentary filling analysis of the Cryogenian–Ediacaran strata in the northern Tarim craton, aiming to decipher the Neoproterozoic basin evolution. Our findings show that the deposition of the Cryogenian strata was controlled by normal faults, representing a rift basin receiving sedimentary materials from both the northern Tarim craton and the Central Tianshan block. In contrast, the Ediacaran developed as a depression basin featured by a wedge-shaped deposition with frequent sea-level fluctuations and simple detrital input from the northern Tarim craton, indicative of a passive margin basin. Such a Neoproterozoic basin evolution of the northern Tarim craton, from the Cryogenian rift to the Ediacaran passive margin, likely resulted from a back-arc extension due to the separation of the Central Tianshan arc from the Tarim craton. These results provide new constraints on the initial opening time of the South Tianshan Ocean at ca. 633 Ma and reveal the Neoproterozoic tectonic affinity of the Central Tianshan block and the northern Tarim craton. Our work also implies that the Tarim craton was located on the periphery of Rodinia, and the South Tianshan Ocean may not be a primary ocean basin of the Paleo-Asian Ocean.