VSP and Seismic Reflection Investigation of Fluid Flow and Structural Evolution at the Oregon Margin Accretionary Prism

会聚边缘增生棱柱是构造复杂的地质特征。这是一项在俄勒冈边缘OM-3站点进行步行垂直地震剖面实验的建议，以成像井眼3公里内垂直和平行于构造走向的结构特征。这将有助于更好地定义锋面逆冲及其相关的幅度异常，以及部分原逆冲带。由于VSP是通过地面震源在钻孔中获取的，因此它们应该能更好地与地面地震数据联系起来。走开式VSP照亮井眼检波器下方的区域，从而对井眼下方和远离井眼的横向结构进行成像。这种横向覆盖将产生振幅与偏移量的信息，这将用于推断锋面逆冲和其他表现出异常振幅的层的流体含量。该合同将支持Moore博士在俄勒冈边缘钻探点3 （OM-3）获得垂直地震剖面（VSP），该钻探点将在ODP Leg 146上钻探。这个实验将提供一个更全面的三维图像，在钻孔半径3公里内的一个吸积棱镜的复杂结构特征。这将有助于更好地理解棱镜内的耦合构造和水文地质系统。VSP还可以将地震信息与取心材料和井眼测井数据进行直接比较。

Convergent margin accretionary prisms are structurally complex geological features. This is a proposal to conduct a walkaway Vertical Seismic Profile experiment at Oregon Margin site OM-3 to image the structural features within 3km of the borehole both perpendicular and parallel to structural strike. This should result in better definition of the frontal thrust and its associ- ated amplitude anomalies as well as part of the protothrust zone. Because the VSP's will be acquired in the drill hole using surface seismic sources, they should provide a better tie to surface seismic data. The walkaway VSP illumunates the zone below the borehole geophone, thereby imaging the structure below and laterally away from the drill hole. This lateral coverage will yield amplitude vs offset information, which will be used for inferring fluid contents of the frontal thrust and other layers that exhibit anomalous amplitudes. This award will support Dr. Moore's efforts to obtain Vertical Seismic Profiles (VSP) at the Oregon Margin drill site 3 (OM-3), which will be drilled on ODP Leg 146. This experiment will provide a more comprehensive three dimensional picture of the complex structural features of an accretionary prism within a three kilometer radius of the borehole. This will lead to a better understanding of the coupled structural and hydrogeologic system within the prism. VSP's will also allow direct comparison of seismic information to cored material and borehole logging data.