Crustal structure of the Mariana Trough
Crustal structure of the Mariana Trough
复制标题
马里亚纳海槽的地壳结构
DOI：
10.1029/jb087ib05p04003
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
D. Hussong
中科院分区：
文献类型：
--
作者：
E. Ambos;D. Hussong
在拟定的轴向裂谷扩展中心附近的马里亚纳海槽中拍摄了三个地震折射剖面。一条长的东西走向线穿过轴向高地区域，即与裂谷带相关的槽的升高部分。另外两条线是在大致的南北方向上拍摄的，与轴向裂谷的趋势大致平行，位于地壳 1 和 5--6 m.y 上。老的。对比这两个剖面的射线追踪分析结果表明，随着地壳年龄的增加，2A层（速度为3.3 km/s）变薄，2B层（速度为5.3 km/s）发育，并且2B层（速度为5.3 km/s）和3A层（速度为6.7 km/s）发育，这意味着地壳演化过程。此外，在几个实例中都发现了大规模地壳断层的存在，这三个线的上地幔地震速度一致，但与先前在年轻洋地壳的其他区域观察到的特征相关，与大西洋中脊和东太平洋海隆等主要活动扩张中心相比，马里亚纳海槽在大多数方面都与前者相似。海槽扩张缓慢（半速率为 1-2 厘米/年），其特点是地形崎岖、轴向裂谷和厚层/sup 2/ 与大西洋中脊一样，马里亚纳海槽地壳中也没有低速区，可以将其解释为扩张中心的岩浆房。
Three seismic refraction profiles were shot in the Mariana Trough in the vicinity of the proposed axial rift spreading center. One long east-west trending line was shot across the axial high region, the elevated portion of the trough associated with the rift zone. The two other lines were shot in a rough north-south orientation subparallel to the trend of the axial rift, on crusts 1 and 5--6 m.y. old. Comparison of the results of the ray-tracing analysis for these two profiles indicated that thinning of layer 2A (velocity of 3.3 km/s) and development of a distinct layer 2B (velocity of 5.3 km/s and development of a distinct layer 2B (velocity of 5.3 km/s) and layer 3A (velocity of 6.7 km/s) takes place with increasing crustal age, implying a process of crustal evolution. The presence of large-scale crustal faults was noted in several instances. In addition, a consistent but low upper mantle seismic velocity of 7.7 km/s was measured for all three lines. These characteristics correlate with those previously observed for other areas of young oceanic crust. When compared with major active spreading centers such as the Mid-Atlantic Ridge and East Pacific Rise, the Mariana Trough appears similar to the formermore » in most respects. Both the Mid-Atlantic Ridge and Mariana Trough are slow spreading (1-2 cm/yr half rate) and are characterized by rough topography, an axial rift, and a thick layer/sup 2/. Like the Mid-Atlantic Ridge, the Mariana Trough also has no low-velocity zone in the crust that could be interpreted as a magma chamber at the spreading center.« less