Oceanic core complexes and crustal accretion at slow-spreading ridges
Oceanic core complexes and crustal accretion at slow-spreading ridges
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DOI：
10.1130/g23531a.1
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发表时间：
2007-07-01
期刊：
影响因子：
5.8
通讯作者：
MacLeod, C. J.
中科院分区：
文献类型：
--
作者：
Ildefonse, B.;Blackman, D. K.;MacLeod, C. J.
洋核杂岩通过滑脱断裂暴露海底的辉长岩，常伴有蛇纹岩化橄榄岩。这些蛇纹岩单位的厚度是未知的。假设这些核心复合体周围的陡峭斜坡提供了一个贯穿结构的横截面，可以推断蛇纹岩构成了至少几百米深处的大部分剖面。然而，深海岩心复合体的深钻已经恢复了辉长岩序列，几乎没有蛇纹岩化的橄榄岩。考虑到辉长岩和蛇纹橄榄岩之间的流变学差异，我们提出了一种修正的海洋岩心杂岩发育模型：大型侵入辉长岩体侵入以橄榄岩为主的储集体，随后在岩体边缘处的应变局部化，最终导致一个凸起的辉长岩心被变形的蛇纹岩包围。因此，海洋岩心复合体可能反映了在缓慢和超缓慢扩张脊的整体岩浆贫乏区域内相对增强的基性侵入期的过程。
Oceanic core complexes expose gabbroic rocks on the sealloor via detachment faulting, often associated with serpentinized peridotite. The thickness of these serpentinite units is unknown. Assuming that the steep slopes that typically surround these core complexes provide a cross section through the structure, it has been inferred that serpentinites compose much of the section to depths of at least several hundred meters. However, deep drilling at oceanic core complexes has recovered gabbroic sequences with virtually no serpentinized peridotite. We propose a revised model for oceanic core complex development based on consideration of the rheological differences between gabbro and serpentinized peridotite: emplacement of a large intrusive gabbro body into a predominantly peridotite host is followed by localization of strain around the margins of the pluton, eventually resulting in an uplifted gabbroic core surrounded by deformed serpentinite. Oceanic core complexes may therefore reflect processes associated with relatively enhanced periods of mafic intrusion within overall magma-poor regions of slow- and ultra-slow-spreading ridges.