The Galapagos Spreading Centre: A Near-Bottom Geophysical Survey
The Galapagos Spreading Centre: A Near-Bottom Geophysical Survey
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加拉帕戈斯扩张中心：近海底地球物理调查
DOI：
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发表时间：
1974
期刊：
影响因子：
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通讯作者：
J. Mudie
中科院分区：
文献类型：
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作者：
K. Klitgord;J. Mudie
摘要对西经86“的加拉帕戈斯扩张中心进行的近底部地球物理调查表明，在快速扩张的海脊上形成的洋壳具有高度划线的性质。水深起伏以小地块为主，这些地块稍微偏离扩张中心，并被向内的陡峭所包围。这种起伏与在缓慢扩张的山脊上发现的相似，但规模较小，当被一层薄薄的沉积物覆盖时，它看起来像典型的深海丘陵地形。利用磁化强度分布、沉积模式和细尺度测深结构确定扩张中心和形成地壳上部的区域。最近的火山活动主要发生在中心2公里以内，这是一个几乎没有沉积物的地区，并且有一个高度磁化的山脊。在以35毫米/年的半速率展开的山脊上，这些观测结果限制了山脊力学的可能模型。似乎有一个宽度为16公里、深度为150米的小型中谷。当坚硬的块体最初在距离中心约2至4公里的中央地壳产生区之外发生断层时，大多数近地表火山活动似乎停止了。中央地块相当平坦，浮雕似乎是由构造火山作用形成的，而中央地块两侧的刚性地块已经略微向外倾斜，并被向内的陡峭所包围。
Summary A near-bottom geophysical survey of the Galapagos spreading centre at 86"W shows the highly lineated nature of oceanic crust generated at a fastspreading ridge. The bathymetric relief is dominated by small blocks which tilt slightly away from the spreading centre and which are bounded by inward-facing scarps. This relief is similar to that found on slow-spreading ridges, but on a smaller scale, and when covered with a thin layer of sediments, it looks like typical abyssal hill terrain. The magnetization distribution, sediment pattern and the fine-scale bathymetric structure are used to locate the centre of spreading and the region in which the upper portion of the crust is being formed. Recent volcanic activity is primarily occurring within 2 km of the centre, a region which is nearly sediment-free and which contains a highly magnetized ridge. Possible models of ridge crest mechanics are constrained by these observations over a ridge spreading with a half-rate of 35 mm/yr. There appears to be a small median valley which has a width of 16 km and a depth of 150 m. Most of the near-surface volcanism appears to cease when the rigid blocks are initially faulted apart from the central crustal generation zone at about 2 to 4 km from the centre. The central block is fairly level with a relief which appears to have been formed by constructional volcanism while the rigid blocks on either side of this central one already are tilted slightly outwards and are bounded by inward facing scarps.