Evidence from en-echelon cross-grain ridges for tensional cracks in the Pacific plate
Evidence from en-echelon cross-grain ridges for tensional cracks in the Pacific plate
复制标题
来自太平洋板块张拉裂缝的阶梯状横纹脊的证据
作者：
E. Winterer;D. Sandwell
太平洋的海底地形主要与原始的扩张方向1对齐，但被板块中部过程产生的对齐所叠加。扩张产生了深海丘陵和断裂带，而板块中部的火山作用产生了孤立的或链状的海山。在Seasat雷达高度计2收集的大地水准面高度数据中发现的另一类地形--“交叉谷粒”，由相距200公里的线形凹槽和隆起组成，与断裂带和深海丘陵倾斜，但与夏威夷链平行。已经提出了三种交叉颗粒模型：小尺度对流，被太平洋板块的剪切组织成纵向卷曲2；压缩屈曲3；以及由板块范围的张应力产生的岩石圈环流4，5。以前获得的数据都没有排除这些模型中的任何一种。在这里，我们报告了多波束测深数据，揭示了沿着横纹的又长又窄的梯形隆起，这被解释为太平洋板块拉张裂缝的证据。
Sea-floor topography in the Pacific is mainly aligned with original spreading directions1, but is overprinted by alignments created by mid-plate processes. Spreading produces abyssal hills and fracture zones, and mid-plate volcanism generates seamounts, isolated or in chains. A different category of topography, the 'Cross-grain', discovered in geoid-height data collected by the Seasat radar altimeter2, comprises linear troughs and swells spaced ∼200 km apart, oblique to fracture zones and abyssal hills but parallel to the Hawaiian chain. Three models have been proposed for the Cross-grain: small-scale convection, organized into longitudinal rolls by the shear of the Pacific Plate2; compressive buckling3; and lithospheric boudinage resulting from plate-wide tensile stresses4,5. None of the previously available data ruled out any of these models. Here we report multi-beam bathymetric data revealing long, narrow en-echelon ridges along the Cross-grain, interpreted as evidence of tension cracks in the Pacific plate.