Targeted 3‐D prestack depth imaging at Legs 190‐196 ODP drill sites (Nankai Trough, Japan)
Targeted 3‐D prestack depth imaging at Legs 190‐196 ODP drill sites (Nankai Trough, Japan)
复制标题
第 190-196 段 ODP 钻探地点（日本南海海槽）的目标 3D 叠前深度成像
DOI：
10.1029/2005gl024191
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发表时间：
2005
影响因子：
5.2
通讯作者：
G. Moore
中科院分区：
文献类型：
--
作者：
Patrizia Costa Pisani;M. Reshef;G. Moore
面向目标的三维叠前深度偏移（PSDM）与南开海槽三个ODP钻井点的关键反射波的已知深度相关，提供了钻孔周围地下深度和P波速度的改进表示。由此产生的速度体积代表“原位”速度，并允许我们将一维测井和岩心速度数据从钻井现场扩展到整个地震断面。PSDM速度梯度与钻井现场的速度梯度非常匹配，尽管速度曲线的绝对值有些不同。在滑脱层上方的PSDM平均垂直速度梯度从海沟轴向海方向的0.99 s−1减小到原冲断层和前缘冲断层带向陆方向的0.87 s−1，在滑脱层处的速度反演约为50-150 m/s。在滑脱构造之下，俯冲段的垂直梯度从盆地中的0.97 s-1减小到前缘逆冲断层之下的0.72 s-1。在盆地和变形前缘之间的俯冲段，横向速度梯度为0.02 s-1，相当于俯冲方向减薄了10%。
Target‐oriented 3‐D prestack depth migration (PSDM), tied to known depths of key reflections at three ODP drill sites in the Nankai Trough, provides an improved representation of the subsurface depths and P‐wave velocities around the drill holes. The resulting velocity volume is representative of the “in situ” velocities and allows us to extend the 1‐D logging and core velocity data from the drill sites to the entire seismic transect. The PSDM velocity gradients closely match those at the drill sites, although the absolute values of the velocity curves are somewhat different. The average PSDM vertical velocity gradient above the décollement decreases from 0.99 s−1 seaward of the trench axis to 0.87 s−1 landward in the proto‐thrust and frontal thrust zone, with a velocity inversion of about 50–150 m/s at the décollement. Below the décollement, the vertical gradient in the underthrusting section decreases from 0.97 s−1 in the basin to 0.72 s−1 beneath the frontal thrust. The lateral velocity gradient in the underthrusting section between the basin and the deformation front is 0.02 s−1, corresponding to ∼10% thinning in the direction of subduction.