RUI: Deep Crustal Structure of the Ivory Coast Basin: an Ocean-Bottom Seismograph Study

RUI：科特迪瓦盆地的深层地壳结构：海底地震仪研究

• 批准号: 9203474
• 负责人: William O'Brien
• 金额: $ 4万
• 依托单位: Southwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-05-01 至 1994-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9203474&HistoricalAwards=false
• 关键词: RUI; Deep; Crustal; Structure; Ivory

This research involves the analysis and interpretation of a large- airgun OBS seismic refraction data set collected in the Gulf of Guinea, offshore West Africa. This data set is a subset of a larger one collected by French scientists in 1990. This part of the African margin is known as the Ivory Coast-Ghana Margin, and is an example of a passive margin formed through transform rifting. The crustal structures developed during transform rifting are relatively poorly understood. Seismic refraction data offer one of the best means of determining crustal thicknesses and structures resulting from this process. Information derived from the seismic refraction data analysis will also be used as part of a site survey for upcoming ODP activities in the area. %%% When continents rift apart, they may do so through divergent (major direction of motion perpendicular to continent-continent boundary line) or transform (major direction of motion parallel to continent-continent boundary line) processes. The latter process has not been studied in as much detail as the former, and is relatively poorly understood. The rifting record is contained in now-buried and submerged structures within passive margins, or trailing edges of continents. These structures can perhaps be best determined through deep seismic sounding techniques. Within the area offshore West Africa known as the Ivory Coast-Ghana Margin, lie submerged features that record the transform rifting that occurred between West Africa and Brazil in the Cretaceous. Ocean Bottom Seismometer seismic refraction data collected in 1990 will be analyzed and interpreted, resulting in a picture of subsurface structures in this region. In addition to answering fundamental questions concerning the nature of structures contained within transform passive margins, the seismic data will be used as background information for upcoming Ocean Drilling Project activities in the area.

这项研究涉及对在西非近海几内亚湾收集的大型气枪OBS地震折射数据集的分析和解释。这个数据集是法国科学家在1990年收集的一个更大的数据集的子集。非洲边缘的这一部分被称为象牙海岸-加纳边缘，是通过转换裂谷形成的被动边缘的一个例子。对转换裂谷过程中形成的地壳结构的了解相对较少。地震折射数据提供了确定这一过程产生的地壳厚度和结构的最佳手段之一。来自地震折射数据分析的信息也将被用来作为即将在该地区进行的ODP型活动的现场调查的一部分。当大陆裂谷分离时，它们可能通过发散(主要运动方向垂直于大陆边界线)或转换(主要运动方向平行于大陆边界线)过程进行。后一种过程没有像前一种过程那样被详细研究，而且对它的了解相对较少。裂谷记录包含在被动边缘或大陆后缘的现已埋藏和被淹没的结构中。这些构造或许最好通过深层地震探测技术来确定。在被称为象牙海岸-加纳边缘的西非近海区域内，埋藏着记录了白垩纪西非和巴西之间发生的改造裂谷的水下地物。将对1990年收集的海底地震仪地震折射数据进行分析和解释，从而形成该地区地下结构的图景。除了回答与转换被动边缘所含构造性质有关的基本问题外，地震数据还将用作即将在该地区开展的大洋钻探项目活动的背景资料。