Tectonic processes along the Middle America Trench inner slope
Tectonic processes along the Middle America Trench inner slope
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中美洲海沟内坡的构造过程
DOI：
10.1144/gsl.sp.1982.010.01.06
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
J. Watkins
中科院分区：
文献类型：
--
作者：
T. Shipley;J. Ladd;R. Buffler;J. Watkins
地球物理资料中观测到的沉积与构造变化的关系，为了解中美洲海沟边缘的构造过程提供了新的思路。我们观察到，一些半深海和远洋海洋沉积物似乎在最底坡下继续相对不变。局限于海底峡谷附近水塘的海沟沉积体通过褶皱和逆冲断裂作用被并入下斜坡。中美洲海沟斜坡底部的这种刮蚀（浅层增生）似乎至少部分取决于海沟填充物的存在。所谓的吸积带的内部结构，其顶部通常在地震反射剖面上通过一个突出的衍射带来识别，在地震反射资料中很少得到解决。由于地震反射和钻探资料均观察到褶皱和其他变形的下坡增加，沿大部分边缘的增生带浅部可能由变形斜坡沉积物组成。在未变形和变形的斜坡沉积物下，如果古沟中存在沟填，则可能发生离刮沟填。代表大部分体积的增生带的较深部分在反射数据中没有得到解决，但可能由其他沉积物或地壳岩石组成，这些沉积物或地壳岩石是在较深的构造水平上由底板作用添加的。
Summary The relationship between sedimentation and structural variations observed in geophysical data provides insight into tectonic processes on the convergent Middle America Trench margin. We observe that some of the hemipelagic and pelagic oceanic sediments seem to continue relatively undeformed beneath the lowermost slope. Trench sediment bodies restricted to ponds in the vicinity of submarine canyons are incorporated into the lower slope by folding and thrust faulting. This offscraping (shallow accretion) at the base of the Middle America Trench slope appears at least partly dependent on the presence of trench fill. The internal structure of the so-called accretionary zone, the top of which is usually identified on seismic reflection profiles by a prominent zone of diffractions, is rarely resolved in the seismic reflection data. The shallow part of the accretionary zone along much of the margin may consist of deformed slope sediments since down-section increase in both folding and other deformation are observed in the seismic reflection and drill data. Beneath the undeformed and deformed slope sediments, offscraped trench fill may occur if trench fill was present in the ancient trench. The deeper part of the accretionary zone representing the bulk of the volume is not resolved in the reflection data but may consist of other sediments or crustal rocks added by an underplating process at deeper structural levels.