Multiple, closely spaced transform faults in fast-slipping fracture zones
Multiple, closely spaced transform faults in fast-slipping fracture zones
复制标题
快速滑移断裂带中存在多个密集的转换断层
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
R. Searle
中科院分区：
文献类型：
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作者：
R. Searle
用远程侧扫声纳GLORIA测量了东太平洋隆起扩张轴在奎布拉达断裂带(S断裂带)和戈法尔断裂带(S断裂带)之间400公里长的偏移量。错动是在三个不同的断裂带中完成的，每个断裂带都包含多达四个由短扩展中心隔开的活动滑动转换断层。变换间隔从5公里到16公里不等。每一次转换都与它自己的横向山谷相关联，但在Quebrada断裂带，以及在其他两个地区，这些山谷在某种程度上合并为一个大的、略有倾斜的断裂带山谷。因此，断裂带山谷的形态趋势不一定能可靠地估计相对板块运动的方向。在快速蔓延的东太平洋隆起上，多重转换断裂带似乎比在缓慢扩张的海脊上常见得多。“构造伸展组构”包括在扩张轴附近形成的近距离的正断层，并与它们近平行地走向，在近距离的变换之间被修改为S形模式。即使在两次变形的中间，这些断层仍与扩散方向成斜角。倾斜的程度随着变换间隔的减小而增加，随着变换的接近，显示出应力椭圆的渐进旋转。
The 400-km-long offset of the East Pacific Rise spreading axis between the Quebrada Fracture Zone (lat 3.5° S) and the Gofar Fracture Zone (lat 4.6° S) has been surveyed using the long-range sidescan sonar GLORIA. The offset is accomplished in three distinct fracture zones, each of which contains up to four actively slipping transform faults separated by short spreading centers. Transform spacings range from 5 to 16 km. Each transform is associated with its own transverse valley, but at Quebrada Fracture Zone, and to some extent at the other two, these valleys merge into one large, slightly oblique, fracture-zone valley. The morphological trends of fracture-zone valleys are therefore not necessarily reliable for estimating directions of relative plate movement. Multitransform fracture zones appear to be much commoner on the fast-spreading East Pacific Rise than on slower spreading ridges. The “tectonic spreading fabric,” which comprises closely spaced normal faults formed near the spreading axes and striking subparallel to them, is modified to a sigmoidal pattern between the closely spaced transforms. Even midway between transforms, these faults remain oblique to the spreading direction. The degree of obliquity increases as the transform separation decreases, showing progressive rotation of the stress ellipse as transforms are approached.