A summary of Deep Sea Drilling Project Leg 67 shipboard results from the Mid-America Trench transect off Guatemala
A summary of Deep Sea Drilling Project Leg 67 shipboard results from the Mid-America Trench transect off Guatemala
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危地马拉附近的中美海沟横断面深海钻探项目第 67 段船上结果摘要
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
Jean Westberg
中科院分区：
文献类型：
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作者：
R. von Huene;J. Aubouin;J. Azéma;G. Blackinton;J. Carter;W. T. Coulbourn;D. Cowan;J. Curiale;C. Dengo;R. Faas;W. Harrison;R. Hesse;D. Hussong;J. Ladd;N. Muzylov;T. Shiki;P. Thompson;Jean Westberg
危地马拉外海的中美洲海沟通过24通道地震反射勘测、地震折射勘测和Glomar Challenger钻井进行了横切。钻探在海洋科科斯板块的三个地点和加勒比板块的四个地点进行。这些板块在约10 cm yr−1处会聚。在所有钻探地点，上中新世至第四纪的沉积物几乎全部为半远洋泥，夹有薄火山灰，但海沟中的泥和细砂浊积岩年龄小于40万年。然而，下面的岩石是非常不同的。在大洋科科斯板块上，中新世早期和中期的底部白垩层序被一薄层深海粘土覆盖。在距离海沟轴向陆地方向仅3 km的位置，钻探穿透了斜坡沉积物，我们恢复了白垩纪至中新世早期的粘土岩序列，该序列位于含有大陆亲缘火成岩的部分上。在目前（中新世-第四纪）的俯冲阶段，沉积物沿着海洋地壳发生了大规模的净俯冲，也许部分大陆框架也已被俯冲。然而，目前还没有一个模型能令人满意地解释海沟斜坡底部令人惊讶的中新世粘土岩的出现。
Summary The Middle America Trench off Guatemala was transected by 24-channel seismic reflection surveys, seismic-refraction surveys, and drilling with the Glomar Challenger. The drilling was done at three sites on the oceanic Cocos plate and four sites on the Caribbean plate. These plates converge at about 10 cm yr−1. At all drill sites sediment of upper Miocene to Quaternary age is almost entirely hemipelagic mud with interbedded thin volcanic ash, except in the trench where mud and fine sand turbidites less than 400 000 yr old are ponded. However, the underlying rocks are very different. On the oceanic Cocos plate a basal chalk sequence of lower and middle Miocene age is overlain by a thin section of abyssal clay. At a site only 3 km landward of the trench axis where drilling penetrated the slope deposits we recovered a Cretaceous to lower Miocene claystone sequence resting on a section containing igneous rock of continental affinity. A large net subduction of sediment along with ocean crust has occurred during the present (Miocene-Quaternary) episode of subduction and perhaps parts of the continental framework have been subducted as well. However, no current model satisfactorily explains the surprising occurrence of Cretaceous-Miocene claystone at the foot of the trench slope.