Structure of the Outer Izu-Bonin Forearc from Seismic-Reflection Profiling and Gravity Modeling
Structure of the Outer Izu-Bonin Forearc from Seismic-Reflection Profiling and Gravity Modeling
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根据地震反射剖面和重力模拟研究伊豆-小笠原外弧前弧的结构
DOI：
10.2973/odp.proc.ir.125.105.1990
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
B. Taylor
中科院分区：
文献类型：
--
作者：
R. Horine;G. Moore;B. Taylor
对伊豆-小笠原岛弧海沟和海沟下斜坡进行的地球物理调查提供了关于该区域若干海山形成时间和模式的新资料。多道地震数据显示，这些海山有一个没有内反射的浅盖（厚度不到1公里），挖掘和取芯结果表明，这是由蛇纹岩构成的。这一盖层下面是地震反射区，可能是蛇纹岩突出的原始基底。海山两侧的沉积序列已被抬升。重力数据表明，海山附近的前弧由低密度物质组成，其深度与滑脱层相同。这些海山经历了几个时期的变形，位于北纬3055 '、东经141° 47'的海山最近甚至可能是目前正在隆起。建议分两个阶段形成这些海山。第一阶段包括小型蛇纹岩底辟突破地表形成蛇纹岩火山。在第二阶段，蛇纹岩侵入火山和在补给管道周围扩大蛇纹化带将导致海山隆起。
Geophysical surveys conducted over the trench and lower trench slope of the Izu-Bonin arc have provided new information on the timing and mode of formation of several seamounts in this region. Multichannel seismic data reveal that these seamounts contain a shallow cap (less than 1 km thick) without internal reflections, which dredging and coring results indicate is made of serpentinite. This cap is underlain by a seismically reflective region that may be the original substrate onto which the serpentinite protruded. Sedimentary sequences flanking the seamounts have been uplifted. Gravity data indicate that the forearc near the seamounts is composed of low-density material that extends as deep as the décollement. These seamounts have experienced several periods of deformation, with the seamount at 3055'N, 141°47'E having undergone very recent, perhaps even current, uplift. A two-stage process is proposed for the formation of these seamounts. The first stage would consist of small serpentinite diapirs breaching the surface to form serpentinite volcanoes. In the second stage, uplift of the seamounts would result from serpentinite intrusions into the volcanoes and a widening zone of serpentinization around the feeder conduits.