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Early Triassic initial collision between the North China and South China blocks in the eastern Qinling Orogenic Belt
Tectonophysics ( IF 2.9 ) Pub Date : 2021-06-12 , DOI: 10.1016/j.tecto.2021.228965
Qianli Ma , Jianghai Yang , Yuansheng Du , Xianduo Dai , Rong Chai , Hua Guo , Yajun Xu

The closure of Mianlue Ocean lead to the collisional assembly between the North China Block (NCB) and the South China Block (SCB). But the timing of initial continental collision remains unclear, with the proposed ages ranging from the Late Permian to the Late Triassic. This study presents stratigraphic, sedimentological, tectonic subsidence, and provenance data from the Triassic strata in the Zigui and Dangyang basins lying along the eastern Qinling Orogenic Belt. These data document a tectonic transition in the central northern-SCB, and locally provide constraints on the timing of initial SCB–NCB collision. The Lower Triassic Daye Formation was deposited in a marginal basin to slope environment, and consists of mudrocks containing detrital zircons with major age peaks at ca. 1900 and 850 Ma. The overlying Lower Triassic Jialingjiang Formation comprises a shallowing carbonate sequence, with intercalated evaporites at the top of the formation. It contains mudrocks that are rich in detrital zircons with of ca. 270‐–245 Ma. The mixed carbonate and siliciclastic sequences of the Middle–Upper Triassic Badong Formation records tectonic uplift at its base, and contains detrital zircons with Usingle bondPb age peaks at ca. 2500, 1850, 920–800, 450 and 350–220 Ma. Combined with petrographical observations and tectonic subsidence calculation, these detrital zircon Usingle bondPb ages record a significant provenance change from recycled material derived from the SCB to newly generated detrital material from the NCB. This provenance change records the initial SCB–NCB collision in the eastern Qinling Orogenic Belt during the Early Triassic.



中文翻译:

东秦岭造山带华北与华南地块早三叠世初始碰撞

绵略海的闭合导致华北地块(NCB)和华南地块(SCB)碰撞组装。但最初大陆碰撞的时间尚不清楚,建议的年龄从晚二叠世到晚三叠世。本研究提供了位于秦岭造山带东部的秭归和当阳盆地三叠纪地层的地层、沉积学、构造沉降和物源数据。这些数据记录了中北部-SCB 的构造转变,并在局部提供了对 SCB-NCB 初始碰撞时间的限制。下三叠统大冶组沉积在边缘盆地到斜坡环境中,由含有碎屑锆石的泥岩组成,主要年龄峰位于约 1900 和 850 马。上覆下三叠统嘉陵江组由浅层碳酸盐层序组成,地层顶部夹有蒸发岩。它包含富含碎屑锆石的泥岩。270--245 毫安。中上三叠统巴东组碳酸盐岩和硅质碎屑岩混合层序记录了其基部的构造抬升,含有U单键Pb 年龄峰值约为。2500、1850、920–800、450 和 350–220 Ma。结合岩相观察和构造沉降计算,这些碎屑锆石 U 单键Pb 年龄记录了从 SCB 回收材料到 NCB 新生成碎屑材料的显着物源变化。这种物源变化记录了早三叠世秦岭造山带东部最初的SCB-NCB碰撞。

更新日期:2021-06-17
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