The Chew Bahir Drilling Project - Deconvolving climatic versus tectonic forcing in the source-to-sink sediment system of extensional provinces: New insights from the Chew Bahir Basin, South Ethiopia

Chew Bahir 钻探项目 - 对伸展省源-汇沉积系统中的气候与构造强迫进行反卷积：来自埃塞俄比亚南部 Chew Bahir 盆地的新见解

• 批准号: 252193660
• 负责人: Professor Dr. Daniel Melnick
• 金额: --
• 依托单位: Instituto de Ciencias de la Tierra
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/252193660?language=en
• 关键词: Chew; Bahir; Drilling; Project; Deconvolving

The complex kinematic evolution of continental rifts and the conspiring effects of climate and tectonics on the surface-process system requires a holistic approach in deciphering paleoenvironmental changes reflected in drill cores. Such an approach must entail the reconstruction of the tectono-geomorphic characteristics of the sediment source-routing-sink system, because erosion and sediment transport are mainly a function of topography, climate, and lithology. Here, we propose such a study of the Chew Bahir catchment in southern Ethiopia, aimed at linking the tectonogeomorphic evolution of the basin with the sediment-routing system, and ultimately the depositional record of the Chew Bahir drilling site, to be obtained under the auspices of the International Continental Drilling Program (ICDP). The recovered drill core is expected to corresponding to an interval spanning at least the ultimate 800-1,200 kyr, targeted to provide data on environmental change to better assess hominin evolution and migration. By integrating our catchment-wide study with the drilling record we aim at deconvolving climatic and tectonic forcing impacting sediment routing and deposition in the Chew Bahir basin. Our results will improve the understanding of three important aspects of the sedimentary records of extensional systems and their relationship with major hominin migration corridors. These include: 1) the forcing mechanisms impacting landscape development; 2) sediment production and deposition; and 3) the paleo-environmental significance of sedimentary deposits in a crucial sector of the East African Rift. In order to achieve these goals, we will follow a four-tiered approach: I) determine the spatiotemporal variations in sediment sources and routing by provenance analysis and dating of fluvial terraces; II) quantify modern and past erosion rates using cosmogenic nuclides and sediment volumes estimated from seismic reflection profiles; III) establish the timing of fluvial captures and drainage reversals in the catchment; and IV) link the tectono-geomorphic evolution with the sedimentary record of the ICDP drillhole. We will use sedimentological techniques in provenance analysis and constrain the age of terrace deposits using cosmogenic nuclides and 14C, to cover a broad age spectrum. Our geomorphic analysis will be aided by 12-m digital elevation models obtained from TanDEM-X data. Together, the tectono-geomorphic analysis, the provenance study, and new geochronology of sedimentary deposits will provide an unprecedented data set that will be ultimately linked to the depositional record of the drillhole in the basin center, thus contributing to our understanding of the link between environmental change and hominin evolution in light of active tectonics and repeated climate change.

大陆裂谷复杂的运动演化以及气候和构造对地表过程系统的共同影响需要采用整体方法来破译钻芯中反映的古环境变化。这种方法必须重建沉积物源-路由-汇系统的构造地貌特征，因为侵蚀和沉积物输送主要是地形、气候和岩性的函数。在这里，我们提出对埃塞俄比亚南部的 Chew Bahir 流域进行这样的研究，旨在将盆地的构造地貌演化与沉积物路径系统联系起来，并最终在赞助下获得 Chew Bahir 钻探地点的沉积记录。国际大陆钻探计划（ICDP）的成员。回收的钻芯预计对应至少跨越最终 800-1,200 kyr 的区间，旨在提供环境变化数据，以更好地评估古人类的进化和迁徙。通过将我们的流域范围研究与钻探记录相结合，我们的目标是对影响周巴赫盆地沉积物路径和沉积的气候和构造强迫进行反卷积。我们的研究结果将增进对伸展系统沉积记录的三个重要方面及其与主要人类迁徙走廊的关系的理解。其中包括：1）影响景观发展的强迫机制； 2）泥沙的产生和沉积； 3）东非裂谷关键区域沉积物的古环境意义。为了实现这些目标，我们将遵循四层方法： I）通过溯源分析和河流阶地年代测定来确定沉积物来源和路线的时空变化； II) 使用从地震反射剖面估计的宇宙成因核素和沉积物体积来量化现代和过去的侵蚀率； III) 确定流域内河流截获和排水逆转的时间； IV) 将构造地貌演化与 ICDP 钻孔的沉积记录联系起来。我们将在物源分析中使用沉积学技术，并使用宇宙成因核素和 14C 来限制阶地沉积物的年龄，以覆盖广泛的年龄范围。我们的地貌分析将借助从 TanDEM-X 数据获得的 12 米数字高程模型。构造地貌分析、物源研究和沉积沉积物的新地质年代学将共同提供前所未有的数据集，最终将与盆地中心钻孔的沉积记录联系起来，从而有助于我们了解沉积物之间的联系。鉴于活跃的构造和反复的气候变化，环境变化和人类进化。

项目成果

Continental rifting at magmatic centres: structural implications from the Late Quaternary Menengai Caldera, central Kenya Rift

岩浆中心的大陆裂谷：肯尼亚中部裂谷晚期第四纪 Menengai 火山口的结构影响

• DOI: 10.1144/jgs2019-021
• 发表时间: 2019
• 期刊: Journal of the Geological Society
• 影响因子: 2.7
• 作者: Riedl; S.; Melnick; D.; Mibei; G.; Njue; L.; Strecker; M.R.
• 通讯作者: M.R.