A Wide-Angle Reflection/Refraction Piggyback of the EDGE Chesapeake Bay Transect

EDGE计划(由地球和海洋科学联合资助)计划于1990年9月在切萨皮克湾海边采集大陆边缘的第二个横断面。霍尔布鲁克博士和珀迪博士将同时收集和处理来自第二艘船的广角海底折射数据，这是一项“背负式”实验。他们的计划是补充垂直入射的MCS数据并以迭代的方式进行工作，以便：1)获得整个边缘的准确2D速度；2)记录下地壳和莫霍面的到达；以及3)在沉积剖面深处发生的碳酸盐堆积。这些数据将使Holbrook和Purdy能够：1)确定莫霍面几何形状；2)确定裂谷阶段地壳的性质；3)提高对大陆和洋壳边界性质的理解；4)接近东海岸磁异常的来源；以及5)测量结晶基底的深度。通过基于该地区现有知识的射线追踪建模，这些研究人员开发了一种优化设计，他们计划沿跨越已知裂谷阶段盆地的2条预定倾斜线部署9个OBH(5个数字-1天记录长度，范围为120分贝；4个模拟，10天，80分贝)。

The EDGE program (supported by joint Earth and Ocean Sciences funding) is scheduled to collect its second transect of a continental margin in September, 1990 seaward of Chesapeake Bay. Drs. Holbrook and Purdy will simultaneously collect and process wide-angle ocean-bottom refraction data from a second vessel in a "piggy-back" experiment. Their plan is to complement and work in an iterative fashion with the vertical-incidence MCS data in order to: 1) derive accurate 2D velocities across the margin; 2) record lower crust and Moho arrivals; and 3) undershoot a carbonate buildup known to occur deep in the sedimentary section. These data will allow Holbrook and Purdy to: 1) determine Moho geometry; 2) determine the nature of rift-stage crust; 3) improve understanding of the nature of bounding continental and oceanic crust; 4) approach an understanding of the source of the East Coast Magnetic Anomaly; and 5) measure the depth to crystalline basement. Through ray-trace modeling based on existing knowledge of the region, these researchers have developed an optimal design of in which they plan to deploy 9 OBHs (5 digital - 1 day recording length with 120 db range; 4 analog, 10 days, 80 db) along 2 scheduled dip lines that cross known rift-stage basins.