Study of volcanic and glacial events and the tectonic system in the context of tectonic regime transition during the Nanhua-Sinian Period in the Tarim block

The Nanhua-Sinian Period represents a critical stage in the tectonic evolution of the Tarim block. The peripheral regions of the basin preserve a record of events such as the breakup of the Rodinia supercontinent, the southward drift of the Tarim block, and the development of rift-depression systems. Research indicates that the dual-layer vertical configuration of the Nanhua rift and Sinian depression is controlled by mechanisms such as the Rodinia mantle plume or subduction of the Paleo-Asian Ocean. However, due to limitations including unclear seismic reflection profiles and a scarcity of wells penetrating the Nanhua-Sinian strata, the deep structure remains poorly understood, and the formation mechanisms of the rift and depression require further discussion. This study employs an integrated multidisciplinary approach to elucidate the characteristics and genetic mechanisms of the dual-layer rift-depression structure in the Tarim block during the Nanhua-Sinian Period. By correlating volcanic-glacial events along the basin periphery, the sequence of tectonic events is clarified, providing essential constraints for understanding tectonic evolution mechanisms. Through paleomagnetic data, the precise positions of the Tarim and adjacent paleoplates from the Early Nanhua to the Early Cambrian are reconstructed, delineating the drift trajectory of the Tarim block following the breakup of Rodinia. Correlation of Nanhua-Sinian strata from wells and field outcrops reveals regional characteristics, offering insights into subsidence and uplift patterns. Based on 2D and 3D seismic data, the tectonic style of the "lower fault and upper depression" in the Manjiaer aulacogen during the Nanhua-Sinian Period is characterized. The results demonstrate that under the extensional stress associated with the Rodinia breakup during the Nanhua Period, the Tarim block experienced intense rifting, with multiple normal faults dipping toward the rift developed along its margins. Combined mantle plume activity in the south and retreating subduction in the north contributed to vigorous thermal activity and a complex rift system during the Nanhua Period. In the Sinian Period, basin evolution was dominated by lithospheric thermal subsidence, with lithospheric cooling and contraction leading to the formation of a depression basin.