Deformation and Alteration Associated With Oceanic and Continental Detachment Fault Systems: Are They Similar?
Deformation and Alteration Associated With Oceanic and Continental Detachment Fault Systems: Are They Similar?
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DOI：
10.1029/2008gm000772
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发表时间：
2010-01-01
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影响因子：
--
通讯作者：
Cheadle, Michael J.
中科院分区：
文献类型：
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作者：
John, Barbara E.;Cheadle, Michael J.
拆离断层及其相关的核杂岩发生在大陆裂谷和洋中脊，代表了地壳伸展的基本模式。大陆和海洋拆离断层的特征是波纹状的穹隆地形;断层表面的暴露在下倾方向上延伸数十公里，倾角厚200米，在变形中表现出渐进的温度连续体。两者都在类似于10（-12）-10（-14）s（-1）的应变速率下形成，并适应不对称延伸。尽管有这些相似之处，这两个系统表现出显着的差异，其形成的环境控制。洋核杂岩形成于较薄的岩石圈中，具有较高的地热梯度，以橄榄石和长石流变为主。相反，大陆的变形受石英和长石的控制。糜棱岩在洋核杂岩中较为少见，在陆核杂岩中较为常见。大洋拆离断层与岩浆加积有着更为密切的联系。在大洋拆离断层中，热液循环和由此产生的蚀变作用更为明显，并控制着低温断层的演化。大洋拆离断层为滚动枢纽型正断层。相反，一些大陆拆离断层以低角度（倾角）开始
Detachment faults and their associated core complexes occur both in continental rifts and at mid-oceanic ridges, and represent a fundamental mode of crustal extension. Both continental and oceanic detachment faults are characterized by corrugated, domal topography; exposures of the fault surface extend tens of kilometers in the downdip direction, with dips 200 m thick, exhibiting a progressive down-temperature continuum in deformation. Both form at strain rates similar to 10(-12)-10(-14) s(-1) and accommodate asymmetric extension. Despite these similarities, the two systems exhibit significant differences, controlled by their environments of formation. Oceanic core complexes form in thinner lithosphere, with higher geothermal gradients, dominated by olivine and feldspar rheology. In contrast, deformation in the continents is controlled by quartz and feldspar. Mylonitic rocks are predicted to be rare in oceanic core complexes and relatively common in continental core complexes. Oceanic detachment faults have a more intimate association with magmatic accretion. Hydrothermal circulation and the consequent alteration are more pronounced in oceanic detachment faults, and dominate the low-temperature fault evolution. Oceanic detachment faults are rolling-hinge-type normal faults. In contrast, some continental detachment faults initiated at a low angle (dips