Ideal Seismic Reflection Site Survey of Lake Edward, Uganda and Zaire, East African Rift

乌干达爱德华湖和东非裂谷扎伊尔理想地震反射现场勘察

• 批准号: 9710146
• 负责人: Christopher Scholz
• 金额: $ 33万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 1999-07-13
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9710146&HistoricalAwards=false
• 关键词: Ideal; Seismic; Reflection; Site; Survey

9710146 Scholz This program is a core project of IDEAL, the International Decade for the East African Lakes. The project will conduct an intermediate-resolution seismic reflection site survey of Lake Edward, in the northern part of the western branch of the East African Rift, in anticipation of subsequent drilling. The primary goal of the drilling program is to chronicle a quantitative high- resolution paleoclimate and paleolimnological history of the basin and surrounding region at 0o-1o S latitude on the East African plateau, extending back through at least two glacial-interglacial cycles. Ancillary goals include answering fundamental questions in the ares of extensional tectonics, and evolutionary biology and macroecology in continental rifts. The principal objectives of this seismic-reflection pre- drilling site survey are to 1) develop a robust sequence- and chron-stratigraphic framework for the upper 1000, of sedimentary section in this half-graben basin, 2) acquire a grid of high- quality, intermediate-resolution multichannel and single-channel seismic reflection data for siting one or more drill holes in the basin, 3) characterize the deformational fabric of the uppermost crust, and 4) determine the total sediment thickness and depth to syn-rift basement in the basin. Important issues to be considered through interpretation of the seismic data set include developing a relative lake level curve for the basin; determining which areas of the lake are likely to contain continuous stratigraphic records; and assessing the intrabasinal deformational fabric for helping determine extension direction in the East African Rift. Integrating the seismic data with the drill hole data sets will permit the development of quantitative, high-resolution models of lacustrine rift basin evolution. Since the primary drilling objectives are focused toward paleoclimate studies and limited to 100-500 m, and a vessel must be transported to the lake for the survey, an intermediate-resolution survey will be carried out using a small air gun seismic source and a short (300-600 m) seismic streamer, to acquire ~ 1500 km of data and image to a depth of ~ 1000 m. ***

小行星9710146 该方案是东非湖泊国际十年的核心项目。 该项目将对东非大裂谷西部分支北方的爱德华湖进行一次中等分辨率地震反射现场勘测，以备以后进行钻探。 钻探计划的主要目标是记录东非高原南纬0 - 1 °盆地及周边地区的定量高分辨率古气候和古湖泊历史，至少可追溯到两个冰期-间冰期旋回。 辅助目标包括回答伸展构造、大陆裂谷演化生物学和宏观生态学战神的基本问题。 本次地震反射钻前现场勘测的主要目标是：1）为该半地堑盆地中的上1000个沉积剖面建立一个可靠的层序和年代地层框架，2）获取一个高质量、中等分辨率的多通道和单通道地震反射数据网格，用于在盆地中定位一个或多个钻孔，（3）确定了盆地最上层地壳的变形组构特征;（4）确定了盆地内沉积物的总厚度和到同裂谷基底的深度。 通过对地震数据集的解释需要考虑的重要问题包括：绘制盆地的相对湖平面曲线;确定湖的哪些区域可能含有连续的地层记录;评估盆地内的变形结构，以帮助确定东非裂谷的延伸方向。 将地震数据与钻孔数据集结合起来，将有助于建立定量的、高分辨率的湖裂盆地演化模型。 由于主要钻探目标集中于古气候研究，并限于100-500米范围内，必须将船只运到湖上进行调查，因此将使用小型气枪震源和短距离震源进行中分辨率调查。（300-600米）地震拖缆，以获取~ 1500公里的数据和~ 1000米深度的图像。 ***