Table2_Mesozoic Tectono-Thermal Event of the Qinshui Basin, Central North China Craton: Insights From Illite Crystallinity and Vitrinite Reflectance.XLSX

The Qinshui Basin is in the Central Orogenic Belt of the North China Craton (NCC), and the production of coalbed methane accounts for 70% of China’s total coalbed methane output. Aiming at the unclear dynamic causes of large-scale coalbed methane accumulation in the basin and the unclear response relationship with the destruction of the NCC, we present joint illite crystallinity and vitrinite reflectance study across the Zijin Mountain and Qincan 1 wells of the Qinshui Basin, respectively. Inverse modeling suggested that tectono-thermal events occurred during the Early Cretaceous, associated with the maximum burial depth and heat flow. The maximum paleo-geothermal temperature and gradient reconstruction results recorded at the Carboniferous strata are 180–190°C and 6.5°C/100 m. The denudation thicknesses recorded by illite crystallinity of Zijinshan and the vitrinite reflectance of the Qincan 1 Well are 3,180.63 m and 3,269.32 m, respectively. We propose that the Qinshui Basin was affected by the extensional environment of the NCC, which caused deep lithospheric thinning and magma upwelling, and a tectono-thermal event occurred during the Early Cretaceous in Qinshui Basin. In addition, the accumulation of coalbed methane, triggered by a tectono-thermal event during the Early Cretaceous, is consistent with the early Cretaceous accumulation and mineralization events in the NCC. Overall, our results reflect the subduction event influence of the western Pacific plate into the East Asian continental plate on the tectono-thermal history of the Central Orogenic Belt of the NCC, which is theoretically significant for clarifying the thermal lithospheric thickness and rheological structure of the basin, as well as the evolutionary history of coalbed methane, and the basin response relationship to the destruction of the NCC.

沁水盆地位于华北克拉通（North China Craton, NCC）中央造山带，其煤层气产量占全国煤层气总产量的70%。针对该盆地大规模煤层气富集的动力学成因不明，以及其与华北克拉通破坏的响应关系不清的问题，我们分别在沁水盆地紫金山与沁参1井开展了伊利石结晶度（illite crystallinity）与镜质体反射率（vitrinite reflectance）的联合研究。反演模拟结果表明，早白垩世发生了构造热事件（tectono-thermal events），该事件与最大埋藏深度及热流密切关联。石炭系地层记录的最大古地温（paleo-geothermal temperature）与古地温梯度重建结果分别为180–190°C和6.5°C/100 m。紫金山地区伊利石结晶度与沁参1井镜质体反射率分别记录的剥蚀厚度（denudation thickness）为3180.63 m与3269.32 m。我们认为，沁水盆地受华北克拉通伸展环境作用，引发了岩石圈（lithospheric）深部减薄与岩浆上涌，且早白垩世该盆地发生了构造热事件。此外，早白垩世构造热事件触发的煤层气富集过程，与华北克拉通早白垩世的成藏成矿事件相一致。综上，本研究结果揭示了西太平洋板块（western Pacific plate）向东亚大陆板块（East Asian continental plate）的俯冲事件对华北克拉通中央造山带构造热历史的影响，这对于明确盆地的热岩石圈厚度与流变结构、煤层气演化历史，以及该盆地与华北克拉通破坏的响应关系均具有重要的理论意义。