Rapid transition from continental breakup to igneous oceanic crust in the South China Sea
Rapid transition from continental breakup to igneous oceanic crust in the South China Sea
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DOI：
10.1038/s41561-018-0198-1
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发表时间：
2018-10-01
影响因子：
18.3
通讯作者：
Zhong, L.
中科院分区：
文献类型：
--
作者：
Larsen, H. C.;Mohn, G.;Zhong, L.
大陆裂解代表了大陆岩石圈成功的裂陷减薄过程，导致板块破裂和洋壳形成的开始。裂解过程中的岩浆活动似乎遵循过度的、短暂的岩浆活动（富含岩浆的边缘）或火成饥饿（缺乏岩浆的边缘）的路径。后一种类型的特征是在火成洋壳形成之前发生极端的大陆岩石圈伸展和地幔折返。贫岩浆边缘的发现提出了关于洋底型岩浆作用开始的基本问题，并指导了对许多裂谷边缘（包括高度延伸的南海北方边缘）地震数据的解释。在这里，我们报告国际海洋发现计划钻探数据从北方南中国海边缘，测试岩浆贫边缘模型以外的北大西洋。与预期相反，结果表明，洋中脊玄武岩型岩浆活动的开始在解体，与一个狭窄的和快速的过渡到火成洋壳。取心和地震资料表明，没有地幔折返的岩石圈快速伸展在两个端元之间产生了边缘结构。软流圈上涌产生大洋中脊玄武岩型岩浆活动从常温地幔在最终解体的解释，反映快速裂谷内薄的前裂谷岩石圈。
Continental breakup represents the successful process of rifting and thinning of the continental lithosphere, leading to plate rupture and initiation of oceanic crust formation. Magmatism during breakup seems to follow a path of either excessive, transient magmatism (magma-rich margins) or of igneous starvation (magma-poor margins). The latter type is characterized by extreme continental lithospheric extension and mantle exhumation prior to igneous oceanic crust formation. Discovery of magma-poor margins has raised fundamental questions about the onset of ocean-floor type magmatism, and has guided interpretation of seismic data across many rifted margins, including the highly extended northern South China Sea margin. Here we report International Ocean Discovery Program drilling data from the northern South China Sea margin, testing the magma-poor margin model outside the North Atlantic. Contrary to expectations, results show initiation of Mid-Ocean Ridge basalt type magmatism during breakup, with a narrow and rapid transition into igneous oceanic crust. Coring and seismic data suggest that fast lithospheric extension without mantle exhumation generated a margin structure between the two endmembers. Asthenospheric upwelling yielding Mid-Ocean Ridge basalt-type magmatism from normal-temperature mantle during final breakup is interpreted to reflect rapid rifting within thin pre-rift lithosphere.