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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The density structure associated with oceanic crustal rifting at the Hess Deep: a seafloor and sea-surface gravity study
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The density structure associated with oceanic crustal rifting at the Hess Deep: a seafloor and sea-surface gravity study

机译：赫斯深处与海洋地壳裂谷有关的密度结构：海底和海面重力研究

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摘要

Seafloor and sea-surface gravity measurements provide new constraints on the lithospheric structure of the Hess Deep at the triple junction between the Pacific, Cocos and Nazca plates. As the Cocos-Nazca ridge propagates westward, breaking into young oceanic crust created at the East Pacific Rise, rocks attributed to the base of the crust or to the upper mantle are exposed on the seafloor at Hess Deep, the tip of the propagator. Seafloor gravity data were collected along two north-south profiles: the western profile runs through the deepest part of the Hess Deep valley, and the eastern profile runs over the tip of the Cocos-Nazca neovolcanic ridge. Shipboard gravity track lines provide coverage of the rift valley from the northern to the southern rim. Bouguer gravity anomalies are negative over the deepest part of the basin and positive north of it at the intra-rift ridge where gabbros and hartzburgites have been drilled. Seafloor and sea-surface gravity data are modeled together in a 2D stochastic inversion and a 3D ideal body inversion. When interpreted in the light of geologic data, gravity results favor an asymmetric emplacement mode for the deep-origin rocks, the alteration of the mantle material playing a key role in the gravity signal. In addition, new magma is emplaced from the east forming a neovolcanic ridge over strongly serpentinized peridotite; the density distribution shows that positive buoyancy cannot be the driving force for magma ascent through the upper crust.
机译：海底和海面重力测量对太平洋，科科斯和纳斯卡板块之间的三重交界处的海斯深层岩石圈结构提供了新的限制。随着Cocos-Nazca山脊向西传播，分解成东太平洋上升带形成的年轻洋壳，归因于地壳底部或上地幔的岩石暴露在海底深处海斯深处，即传播者的尖端。海底重力数据是沿两个南北剖面收集的：西部剖面贯穿赫斯深谷的最深部分，东部剖面遍及科科斯－纳斯卡新火山脊的尖端。船上重力跟踪线覆盖了从北部到南部边缘的裂谷。布格重力异常在盆地最深处为负值，在盆地北部为正向，在裂谷内脊上钻有长辉石和哈茨伯格岩。海底和海面重力数据在2D随机反演和3D理想物体反演中一起建模。当根据地质数据进行解释时，重力结果有利于深部岩石的非对称位移模式，地幔物质的变化在重力信号中起关键作用。另外，新的岩浆从东部进入，在强烈蛇纹石化的橄榄岩上形成了新火山脊。密度分布表明，正浮力不能成为岩浆通过上地壳上升的驱动力。

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