Anatomy of a Passive Continental Margin: Deep Structure of Transitional Crust and the Source of the East Coast MagneticAnomaly

许多MCS，磁力和重力测量集中在 确定美国东部的基本结构特征 海岸大陆边缘。 不幸的是， 裂陷、构造沉降、减薄和早期 火山活动都受到成像困难的阻碍 最深的“裂谷阶段”地壳下面的几个边缘- 平行盆地 最近的一个MCS计划描绘了卡罗莱纳号 沿沿着两条边缘垂直线部署8个OBH 线霍尔布鲁克医生和珀迪医生已经开始处理这些 数据 目前的奖励将允许他们继续充分 波场成像和2D射线跟踪建模， 垂直入射MCS的速度结构和成像 数据区. 此外，还提供支助， 沿着类似的边界部署一系列附加的OBH 在切萨皮克湾近海进行横断面调查。 这是暂时的 计划在1990年的春季或夏季举行 的具体目标 这两个实验都是为了确定莫霍面几何形状、基底 深度，以及中间裂谷阶段的各种特征 地壳。 后者的例子包括沿走向变化 裂谷期地壳的厚度、宽度和速度 作为内部结构，反射性质，和性质的 与“正常”大陆和海洋地壳的横向边界。

Numerous MCS, magnetic and gravity surveys have concentrated on determining fundamental structural features of the US East Coast continental margin. Unfortunately, firm constraints on the nature of rifting, tectonic subsidence, thinning and early volcanism have all been hampered by the difficulty of imaging the deepest "rift-stage" crust that underlies several margin- parallel basins. A recent MCS program profiled the Carolina Trough, and 8 OBHs were deployed along two margin-perpendicular lines. Drs. Holbrook and Purdy have begun processing these data. The present award will allow them to continue full wavefield imaging and 2D ray trace modeling that will improve velocity structure and imaging of the vertical-incidence MCS profiles. In addition, support is provided to prepare for an additional series of OBH deployments along a similar margin transect offshore Chesapeake Bay. This is tentatively scheduled for the Spring or Summer of 1990. Specific goals of both experiments are to determine Moho geometry, basement depths, and various features of the intervening rift-stage crust. Examples of the latter include along-strike variations in thickness, width, and velocity of rift-stage crust, as well as internal structure, reflection character, and nature of the lateral boundaries with "normal" continental and oceanic crust.