Origin and History of Abyssal Hills in the Northeast Pacific Ocean
Origin and History of Abyssal Hills in the Northeast Pacific Ocean
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东北太平洋深渊山的起源和历史
DOI：
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发表时间：
1970
期刊：
影响因子：
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通讯作者：
B. Luyendyk
中科院分区：
文献类型：
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作者：
B. Luyendyk
利用精确导航的（± 15 m）近海底地球物理仪器包，对东北太平洋（32° 25′N，125° 45′W附近）两个南北走向的深海丘陵进行了详细的区域调查，探讨了深海丘陵的形成方式和位置问题。西山是一个细长的盾状火山，东山是一个块断层（地垒）结构。这两座山都是大约40公里乘10公里，有几百米的浮雕。西山是由火山作用形成的，大约3000万年。在东太平洋隆起的顶峰几十米深海沉积物堆积后，断层活动开始，使中央谷下降，形成地垒。与此同时，熔岩流覆盖了沉积物表面的大面积区域。热流测量表明，该地区可能是火山活跃。西部火山山和其他在快速扩张的隆起顶部形成的山丘的形成模式是熔岩流和小的圆锥形火山球的积累。这些旋钮直径不到一公里，高数十米。在东北太平洋其他地区形成的深海丘陵，如地垒，可能是由于海底扩张方向改变时洋壳变形而造成的。由于一个紧密间隔的，二维的结构颗粒的弱点，是冻结在洋壳中的上升波峰，无论是新的和旧的地形有相同的走向。
The questions of how and where abyssal hills are formed were investigated by means of a detailed areal survey of two north-south trending abyssal hills in the northeast Pacific (vicinity 32° 25′N, 125° 45′W) using an accurately navigated, (±15m) near-bottom geophysical instrument package. The western hill is an elongate shield volcano, and the eastern hill is a block fault (horst) structure. Both hills are approximately 40 km by 10 km and have several hundred meters of relief. The western hill was formed by volcanic processes about 30 m.y. ago at the crest of the East Pacific Rise. Episodes of faulting initiated after accumulation of tens of meters of pelagic sediments, downdropped the central valley and created the horst. At the same time lava flows covered wide areas of the sediment surface. Heat-flow measurements show that the area may be volcanically active. The proposed mode of formation of the western volcanic hill, and other hills formed at the crest of a fast spreading rise, is by accumulation of lava flows and small, conical volcanic knobs. These knobs are less than a kilometer in diameter and tens of meters high. Abyssal hills, like the horst, that formed in other areas of the northeast Pacific may have been caused by faulting of the oceanic crust as it was deformed during a change in sea-floor spreading direction. Because of a closely spaced, two-dimensional structural grain of weakness that is frozen in the oceanic crust at a rise crest, both the younger and older topography have the same strike.