Evolution of magma-poor continental margins from rifting to seafloor spreading
Evolution of magma-poor continental margins from rifting to seafloor spreading
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DOI：
10.1038/35093085
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发表时间：
2001-09
期刊：
影响因子：
64.8
通讯作者：
R. Whitmarsh;G. Manatschal;T. Minshull
中科院分区：
文献类型：
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作者：
R. Whitmarsh;G. Manatschal;T. Minshull
大陆的裂谷作用涉及断裂（构造作用）和岩浆作用，反映了地球内部固态变形和减压融化的应变速率和温度依赖过程。这种裂谷作用的大多数模型分别处理构造作用和岩浆作用，很少有数值模拟试图包括大陆分裂和融化，更不用说描述大陆裂谷作用如何演变成海底扩张了。这种演化模式通常将大陆地壳和海洋地壳并列。在这里，我们提出的观测结果支持在大陆边缘的海洋和大陆地壳之间存在一个被挖出的大陆地幔带，宽数十公里，在那里发生了岩浆匮乏的裂谷作用。我们介绍了西伊比利亚边缘的地球物理和地质观测，，，，，以及现在暴露在阿尔卑斯山的前特提斯海洋边缘的地质填图，，，，，。我们利用这些互补的发现提出了一个概念模型，该模型侧重于大陆伸展和分裂的最后阶段，以及大陆地幔被挖掘的区域的形成，该区域向海洋演化为海底扩张。我们认为，演化的应力场和热场受到软流圈地幔脊上升和变窄的约束，岩浆活动和向海洋扩展的速率系统地增加。
The rifting of continents involves faulting (tectonism) and magmatism, which reflect the strain-rate and temperature dependent processes of solid–state deformation and decompression melting within the Earth,. Most models of this rifting have treated tectonism and magmatism separately, and few numerical simulations have attempted to include continental break-up and melting, let alone describe how continental rifting evolves into seafloor spreading. Models of this evolution conventionally juxtapose continental and oceanic crust. Here we present observations that support the existence of a zone of exhumed continental mantle, several tens of kilometres wide, between oceanic and continental crust on continental margins where magma-poor rifting has taken place. We present geophysical and geological observations from the west Iberia margin,,,,, and geological mapping of margins of the former Tethys ocean now exposed in the Alps,,,,,. We use these complementary findings to propose a conceptual model that focuses on the final stage of continental extension and break-up, and the creation of a zone of exhumed continental mantle that evolves oceanward into seafloor spreading. We conclude that the evolving stress and thermal fields are constrained by a rising and narrowing ridge of asthenospheric mantle, and that magmatism and rates of extension systematically increase oceanward.