SGER: Late Cenozoic Rift Sedimentation, Volcanism and Tectonism in the Northern Afar: Geological Setting of the Danakil Region of Eritrea

SGER：北远地区晚新生代裂谷沉积、火山活动和构造作用：厄立特里亚达纳基尔地区的地质背景

• 批准号: 9700870
• 负责人: Robert Walter
• 金额: $ 1.62万
• 依托单位: Institute of Human Origins
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-15 至 1998-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9700870&HistoricalAwards=false
• 关键词: SGER; Late; Cenozoic; Rift; Sedimentation

9700870 Walter In 1992, Eritrea emerged as an independence nation after a thirty year war. In June 1993, we contacted colleagues at the Earth Science Unit, University of Asmara concerning the feasibility of beginning geological and paleontological research in Eritrea. At their invitation, Walter visited Eritrea in July 1994 and met with the University of Asmara, the Geological Survey, the Ministry of Mines and Energy, the National Museum, and the Ministry of Culture. This paved the way for a reconnaissance field survey in the summer of 1995. A field permit was granted in March, 1996 (Attachment 1). We propose to investigate the Danakil Depression of Eritrea, which is the northernmost segment of the Afar Rift system, itself a major branch of the East African Rift. Specifically, we will investigate the northern Danakil Depression, the escarpments adjacent to the Depression, and the sedimentary basins along the Red Sea coast north of the Danakil (Fig. 1). Our primary objective is to study the origin and evolution of tectonism, vol.canism, and sedimentation in an area where oceanic and continental rift processes merge. We are specifically interested in the interplay between voicanism and tectonism as they relate to sedimentary basin formation, and the correlation between terrestrial and marine sequences. A secondary objective is to survley the rift basins for hominid-paleontological and archaeological occurrences. Results and observations from this study will provide insights into early hominid evolution in Eritrea. In a broad sense the project concerns the first systematic survey of late Cenozoic sedimentary basins in Eritrea for their integrated geological, paleontological and archaeological content. This proposal seeks funds to partially support an exploratory field project to begin January, 1997. Investigators in this preliminary phase are: (1) Richard Buffler (University of Texas, Austin; sediment basin analysis, regional tectonics); (2) Seife Behre (Eritrean citizen, in priva te consulting in Eritrea; remote sensing, regional tectonics); (3) Tesfaye Yemane (Eritrean citizen, Ph.D. candidate, Iowa State University; sedimentology and stratigraphy); (4) Twiede Medhin Tecle (Eritrean citizen; Eritrean Ministry of Mines and Energy; regional geology); (5) Semere Solomon (Eritrean citizen; University of Asmara; structural geology; (6) Carl Vondra (Iowa State University; stratigraphy, sedimentology, rift basin analysis) and (7) Robert Walter (Institute of Human Origins, geochronotogy, volcanology, regional tectonics). Partial support is provided by a grant from Anadarko Petroleum Corporation (Budget). This is a preliminary project in an area that has only recently been opened to scientific investigations. One of our goals is to test a sequence stratigraphic approach to terrestrial basin analysis. Stratigraphic sections will be subdivided into a regional framework using laterally extensive chronostratigraphic markers, including unconformities (base level falls, down cutting), flooding events (base level rises, aggradation), and interbedded volcanic units (flows and tephra beds) that witl be radiometrically dated. Several unconformities and numerous volcanic units were observed during a reconnaissance survey to this area in 1995. An attempt will be made to identify sedimentary cycles within adjacent marine and nonmarine sections, and to relate them to sea level and climatic base-level cycles, and to use them as correlation tools. We will use this information to test models of rift evolution. Our secondary objective, to identify potential hominid-bearing paleontological sites, is also a testable hypothesis. The prospect of early hominid fossils in the Dana.U was initially theoretical, based on the hypothesis that the sedimentary basins of northern Afar formed under similar tectonic, geological, and paleoenvirom-nental conditions as hominid-bearing deposits of the central Afar, where several geological and anthropological research groups (including IHO's Hadar Research Project) have been working for nearly twenty years. However, in December 1995 a hominid skull (species uncertain) was found by an Italian geological research team (led by E. Abbate of the University of Florence) in Plio-Pleistocene sediments near Buia along the flanks of the Danakil Depression. Their discovery is significant for it shows that early hominids are indeed present in the late Cenozoic sediments of the Danakil basin, and that this secondary objective has a high probability of success. The project merits consideration as a Small Grant for Exploratory Research because it is preliminary work on untested and novel ideas (e.g., terrestrial sequence stratigraphy and early hominid exploration). There is also an urgency to conduct field work, since the Eritrean government may not hold the permit indefinitely. Preliminary 4OAr/ 39Ar dating of volcanic rocks collected during this study will be done at the University of Toronto by RCW in the laboratory of Prof. Derek York.

9700870沃尔特（Walter）在1992年，厄立特里亚（Eritrea）在三十年之后成为一个独立国家。 1993年6月，我们与阿斯马拉大学（University of Asmara）的地球科学部门的同事有关开始厄立特里亚（Eritrea）的地质和古生物学研究的可行性。 应他们的邀请，沃尔特（Walter）于1994年7月访问了厄立特里亚（Eritrea），并会见了阿斯马拉大学（University of Asmara），地质调查局，矿业和能源部，国家博物馆和文化部。 这为1995年夏天的侦察现场调查铺平了道路。1996年3月（附件1）授予了现场许可证。 我们建议调查厄立特里亚的达纳基尔萧条，这是远处裂谷系统的最北端，本身就是东非裂谷的主要分支。 具体来说，我们将调查达纳基尔北部的抑郁症，与抑郁症相邻的悬崖以及达纳基尔以北的红海沿岸的沉积盆地（图1）。 我们的主要目标是研究海洋和大陆裂谷过程合并的地区构造，vol.Canism和沉积的起源和演变。 我们对与沉积盆地形成有关的语音主义和构造主义之间的相互作用特别感兴趣，以及陆地和海洋序列之间的相关性。 次要目标是将裂谷盆地归因于人类的生物学和考古事件。 这项研究的结果和观察结果将为厄立特里亚的早期人类发展提供见解。 从广义上讲，该项目涉及对厄立特里亚的新生代沉积盆地的首次系统调查，以构成其整合的地质，古生物学和考古含量。 该提案寻求资金部分支持1997年1月开始的探索性现场项目。该初步阶段的调查人员是：（1）理查德·巴夫勒（Richard Buffler）（德克萨斯大学奥斯汀大学； Sediment Basin分析，区域构造）； （2）Seife Behre（厄立特里亚公民，在厄立特里亚的私人咨询中；遥感，区域构造）； （3）Tesfaye Yemane（厄立特里亚公民，爱荷华州立大学候选人；沉积学和地层学）； （4）Twiede Medhin Tecle（厄立特里亚公民；厄立特里亚矿山和能源部；区域地质）； （5）半所罗门（厄立特里亚公民；阿斯马拉大学；结构地质学；（6）卡尔·范德拉（爱荷华州立大学；地层，沉积物学，裂谷盆地分析）和（7）罗伯特·沃尔特（Robert Walter）直到最近才对科学研究开放的领域的初步项目。在1995年对该地区的侦察调查中，观察到几个不整合的单位（流量和tephra床）。 我们将使用此信息来测试裂谷进化的模型。 我们的次要目标是识别潜在的人性化古生物学地点，也是一个可检验的假设。 基于以下假设：北部北部的沉积盆地在类似的构造，地质和古envirom nental条件下形成，如中央大街的人性化沉积物，在其中的几个地质学研究小组（包括IHO研究小组）（包括IHO HASTAR研究的项目）（包括几乎是在此工作）。 然而，1995年12月，意大利地质研究小组（由佛罗伦萨大学的E. Abbate领导）在北北抑郁症的侧面发现了一个人类的头骨（物种不确定）。 他们的发现很重要，因为它表明，早期的人类确实存在于达纳基尔盆地的晚期库综合沉积物中，并且这个次要目标具有很高的成功可能性。 该项目值得考虑探索性研究的小赠款，因为它是关于未经测试和新颖思想的初步工作（例如，陆地序列地层学和早期人类探索）。 由于厄立特里亚政府可能不会无限期持有许可证，因此也有迫切需要进行现场工作。 在本研究期间收集的火山岩的初步4OAR/ 39AR年代将由RCW在多伦多大学在Derek York教授的实验室中进行。