The Jurassic period represents a pivotal phase in the Mesozoic tectonic evolution of the North China Block (NCB), marked by the closure of the Mongol-Okhotsk Ocean and the initiation of Paleo-Pacific subduction. The Jurassic clastic successions of the Liaodong Peninsula (LP), situated in the northeastern NCB at a critical tectonic junction, serve as a key archive for deciphering the complex geodynamic processes that shaped the northern margin of the NCB (NMNCB). Based on an integrated provenance analysis of the Jurassic Tianshifu section in the LP, utilizing detrital zircon U-Pb dating, Hf isotopes, zircon trace elements, sandstone framework composition, and heavy mineral assemblages, this study reveals a clear provenance evolution. The Early-Middle Jurassic sediments were consistently sourced from a mixed provenance involving the NMNCB and the Xing-Meng Orogenic Belt (XMOB). A significant shift occurred in the Late Jurassic, marked by an increased contribution from the NMNCB, a decrease from the XMOB, and a minor input of local material. Regional comparison of sedimentary-provenance systems reveals that the central-western segment of the NMNCB (west of the Tan-Lu fault) had lost its detrital connection with the XMOB by the Late Jurassic, due to the development of intracontinental uplift along the northern margin. In contrast, in the eastern segment of the NMNCB (e.g., the LP), XMOB-derived detritus remained a significant component during the Late Jurassic, indicating that the marginal uplift did not form a complete barrier there. Based on these spatiotemporal patterns of differential uplift, we propose that the geodynamic mechanism governing the NMNCB was primarily associated with the west-to-east scissor-like closure of the Mongol-Okhotsk Ocean.
Xu et al. (Wed,) studied this question.
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