Late Cretaceous-Cenozoic intraplate extension and tectonic transitions in eastern China: Implications for intraplate geodynamic origin
Late Cretaceous-Cenozoic intraplate extension and tectonic transitions in eastern China: Implications for intraplate geodynamic origin
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中国东部晚白垩世-新生代板内伸展与构造转换：板内动力学成因的意义
DOI：
10.1016/j.marpetgeo.2020.104379
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发表时间：
2020-07
影响因子：
4.2
通讯作者：
Lulu Wu;L. Mei;D. Paton;Yunsheng Liu;P. Guo;Chuanbo Shen;Zhaoqian Liu;Jin Luo;Caizheng Min-Caizhe
中科院分区：
文献类型：
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作者：
Lulu Wu;L. Mei;D. Paton;Yunsheng Liu;P. Guo;Chuanbo Shen;Zhaoqian Liu;Jin Luo;Caizheng Min-Caizhe
板内伸展的地球动力学起源仍然知之甚少。对于中国东部晚白垩世-新生代板内伸展作用，由于缺乏对重大构造转型的全面认识，其驱动机制仍存在很大争议。本研究以白垩纪构造演化为背景，综合江汉盆地、渤海湾盆地和浙江地区多学科资料，首次建立了晚白垩世-新生代地球动力学成因的综合观点。晚白垩世，江汉盆地内存在裂谷作用，沉积中心位于渤海湾盆地中部。在新生代，裂谷和沉积中心最初集中在西部盆地，然后逐步向东迁移，而不是继续向东迁移。新生代中期（50-23 Ma）裂谷作用和火山作用显著增强，中国东部裂谷盆地在新生代中期（~26-23 Ma）末全部废弃。晚新生代（23-0 Ma）浙江地区火山活动明显增强。从晚白垩世（100-65 Ma）到早新生代（65-50 Ma），两个裂谷盆地下的软流圈地幔源区同位素更贫化，熔融程度增加;然而，从早新生代到中新生代，软流圈地幔源区同位素更富集，不均匀，熔融程度降低（挥发分含量显著降低）。新生代晚期浙江地区的地幔源比新生代中期更加亏损和不均匀，熔融程度也有所增加。这三个阶段的构造转换和构造相关性直接制约了中国东部板内伸展与相邻板块运动之间的因果关系。中国东部晚白垩世-新生代的板内伸展和构造转换依次受到晚白垩世古太平洋板块回滚、早-中新生代印度-亚洲碰撞和晚新生代太平洋板块俯冲与印度-亚洲碰撞的共同驱动。我们的研究为揭示板内伸展的地球动力学起源提供了一个综合的视角。
The geodynamic origin of intraplate extension remains poorly understood. For the case of the Late Cretaceous-Cenozoic intraplate extension in eastern China, its driving mechanism remains highly controversial due to the absence of a comprehensive understanding of significant tectonic transitions. This study uses the well-documented Cretaceous tectonic evolution as a background and integrates extensive multidisciplinary data in the Jianghan Basin, Bohai Bay Basin and Zhejiang area, to develop an integrated view of the Late Cretaceous-Cenozoic geodynamic origin for the first time. During the Late Cretaceous, rifting and depocentres were distributed in the Jianghan Basin and were located in the central Bohai Bay Basin. During the Cenozoic, rifting and depocentres were initially focused in the western basins and then progressively migrated eastward, rather than continuing migrating eastward. The rifting and volcanism during the Middle Cenozoic (50-23 Ma) significantly increased, and all rift basins in eastern China were abandoned at the end of the Middle Cenozoic (~26-23 Ma). The volcanism in the Zhejiang area was markedly enhanced during the Late Cenozoic (23-0 Ma). The asthenospheric mantle sources beneath the two rift basins were isotopically more depleted with an increased extent of melting from the Late Cretaceous (100-65 Ma) to Early Cenozoic (65-50 Ma); however, they became isotopically more enriched and heterogenous with a decreased melting extent (significantly reduced volatile content) from the Early Cenozoic to Middle Cenozoic. The mantle source beneath the Zhejiang area during the Late Cenozoic was isotopically more depleted and heterogeneous than during the Middle Cenozoic, with an increased extent of melting. These three-phase tectonic transitions together with tectonic correlations directly constrain the causal relationships between the intraplate extension in eastern China and the motions of the adjacent plates. Consequently, we propose that the Late Cretaceous-Cenozoic intraplate extension and tectonic transitions in eastern China were successively driven by the Paleo-Pacific slab rollback during the Late Cretaceous, the India-Asia collision during the Early-Middle Cenozoic and by the combination of the subduction of the Pacific Plate and India-Asia collision during the Late Cenozoic. Our study provides an integrated perspective for unraveling the geodynamic origin of intraplate extension.