1 MA EAST PACIFIC RISE OCEANIC-CRUST AND UPPERMOST MANTLE EXPOSED BY RIFTING IN HESS DEEP (EQUATORIAL PACIFIC-OCEAN)
1 MA EAST PACIFIC RISE OCEANIC-CRUST AND UPPERMOST MANTLE EXPOSED BY RIFTING IN HESS DEEP (EQUATORIAL PACIFIC-OCEAN)
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DOI：
10.1016/0012-821x(90)90160-y
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发表时间：
1990-12-01
影响因子：
5.3
通讯作者：
BLUM, N
中科院分区：
文献类型：
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作者：
FRANCHETEAU, J;ARMIJO, R;BLUM, N
法国潜水器Nautile在Cocos-Nazca传播器尖端的加拉帕戈斯三重连接点区域进行了一系列潜水。 大多数潜水都是为了研究赫斯深海，这是一个由快速扩张的东太平洋隆起轴线上的海洋地壳断裂而形成的裂谷。 这些潜水使结构和岩性能够得到评估，并证实了早期的疏浚证据，即位于赫斯深渊轴线以北的裂谷内脊上有丰富的基底地壳和地幔岩。 这表明，这种情况并不是缓慢扩张海脊所特有的。 一个几乎完整的和独特的日志年轻（1马）地壳和上地幔代表非常快速的增生，可以重建，即使该部分是不连续的，高度肢解。 我们提出了两个模型，可以解释暴露在洋底的深基础的海洋地壳。 一种模式强调对称性和垂直构造通过蛇纹化地幔的等倾/底辟作用。 另一种模式需要更大的伸展量，并强调通过低角度拆离断层作用对上地壳剥蚀的不对称性。 在这两种模式中，其主要区别在于在深度上的结构，东太平洋隆起地壳的Cocos-Nazca传播端的岩浆伸展导致下地壳和上地幔的隆起和剥蚀。
A series of dives with the French submersible Nautile has been conducted in the region of the Galapagos triple junction, at the tip of the Cocos-Nazca propagator. Most of the dives were devoted to the study of Hess Deep, a rift valley produced by rifting of oceanic crust created at the axis of the very fast-spreading East Pacific Rise. The dives have enabled the structures and lithologies to be assessed and confirmed earlier dredging evidence for abundant basal crust and mantle rocks on an intra-rift ridge located to the north of the axis of Hess Deep. This shows that this situation is not specific of slow-spreading ridges. A nearly complete and unique log of young (1 Ma) crust and uppermost mantle representative of very fast accretion can be reconstructed even though the section is discontinuous and highly dismembered. We propose two models that can explain the exposure on the ocean floor of the deep foundation of the oceanic crust. One model stresses symmetry and vertical tectonics through isostasy/diapirism of serpentinized mantle. Another model requires a larger amount of extension and emphasizes asymmetry with denudation of the upper crust through low-angle detachment faulting. In both models, which differ mainly in the structure at depth, amagmatic extension of East Pacific Rise crust by the Cocos-Nazca propagator tip results in uplift and denudation of lower crust and upper mantle.