Cenozoic sill intrusion in the central and southern East China Sea Shelf Basin
Cenozoic sill intrusion in the central and southern East China Sea Shelf Basin
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东海陆架盆地中南部新生代岩床侵入
DOI：
10.1016/j.marpetgeo.2020.104465
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发表时间：
2020
影响因子：
4.2
通讯作者：
Zhao Tianliang
中科院分区：
文献类型：
--
作者：
Yao Zewei;Li Chun-Feng;He Guangyu;Tao Tiansheng;Zheng Xiaoli;Zhang Tao;Tang Xianjun;Zhao Tianliang
以玄武岩为主的新生代火成岩零星出露于中国东部陆上，为研究该区新生代演化提供了重要信息。重要的是，在200至600公里宽的近海大陆架区域，它们的几何形状和分布仍然没有得到很好的限制。利用地震剖面资料，研究了东海陆架盆地中南部广泛分布的133个火成岩岩床的几何特征。在多条地震剖面上，高振幅、连续地震反射中的岩床多出现在1.1- 3.3s的时间间隔内，对应的深度范围为1.1- 4.8km。它们可分为五种类型：碟形岩床、层整合岩床、岩盖岩、斜席和混合岩床。其中，碟形窗台占主导地位。与这些火成岩岩床有关的地层变形表明，自中新世以来岩床侵入已变得强烈，并可能影响ECSSB的石油系统。由岩床诱导形成的强制褶皱是有潜力的油气圈闭。我们推断，岩床侵入在ECSSB是由于岩浆上涌造成的脱水和/或小规模的对流在一个大的地幔楔以上的停滞太平洋板块。早中新世以来，菲律宾海板块的俯冲导致了东中国海板块的构造反转和冲绳海槽的伸展，在构造减薄的东中国海板块中引发了更多的岩浆活动。在ECSSB薄地壳上的厚沉积地层可能引起了更多的侵入比喷出新生代岩浆活动。
Cenozoic igneous rocks dominated by basalts are exposed sporadically onshore East China, and they provide important information about the Cenozoic evolution of the region. Importantly, their geometries and distribution are still not well constrained in the 200–600 km wide offshore continental shelf region. Based on seismic profiles, this study presents the geometric characteristics of 133 igneous sills that are widely distributed in the central and southern regions of the East China Sea Shelf Basin (ECSSB). Sills in high-amplitude, continuous seismic reflections mostly occur in a time interval of 1.1–3.3 s in multiple seismic profiles, corresponding to a depth range of 1.1–4.8 km. They can be classified into five types: saucer-shaped sills, strata-concordant sills, laccoliths, inclined sheets, and hybrid sills. Of these, the saucer-shaped sills predominate. Strata deformation associated with these igneous sills indicate that sill intrusion has become intense since the Miocene, and it potentially affected petroleum systems in the ECSSB. Forced folds induced by the sills are prospective petroleum traps. We infer that sill intrusion in the ECSSB was due to magma upwelling caused by dehydration and/or small-scale convection in a large mantle wedge above the stagnant Pacific slab. The subduction of the Philippine Sea plate resulted in tectonic inversion in the ECSSB and extension in the Okinawa Trough since the Early Miocene triggered more magmatism in the tectonically thinned ECSSB. Thick sedimentary strata over a thin crust in the ECSSB may have induced more intrusive than extrusive Cenozoic magmatism.