(ESH) Collaborative Research: Lake Quaternary Climatic and Glacial History of Africa from Cosmogenic Dating of Glacial and Lake Deposits

(ESH) 合作研究：根据冰川和湖泊沉积物的宇宙成因测年研究非洲第四纪湖泊气候和冰川历史

• 批准号: 9632277
• 负责人: Marek Zreda
• 金额: $ 22.56万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-01 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9632277&HistoricalAwards=false
• 关键词: ESH; Collaborative; Research; Lake; Quaternary

9632277 Zreda Reconstruction of the timing and extent of past glaciers and closed-basin lakes is critical for understanding regional and global climatic changes during the Quaternary. Such data are critically needed in the tropics, and equatorial Africa in particular, because of considerable discrepancy between paleoclimates deduced from terrestrial records and those calculated using general circulation models. Development of high quality terrestrial paleoclimatic data bases is one of the primary research needs in paleoclimatology. The proposed research contributes to fulfilling these needs by providing accurately dated, quantitative climatic proxy data for climatically sensitive locations in the equatorial and subequatorial Africa. Glacial deposits have been recognized and mapped in alpine regions of subtropical northwestern (the High Atlas) and tropical east-central Africa (Kenya and Kilimanjaro, among others). At these locations, multiple moraine systems record past glacier extent and provide an important proxy of previous climatic fluctuations. Very few of these landforms have been numerically dated because of lack of datable material associated with glacial deposits. Consequently, local chronologies have been based mainly on stratigraphic relationships between landforms and comparative relative weathering studies. We propose to use cosmogenic isotope dating methods (36Cl,10Be, 26Al,14C, 21Ne and 3He) to establish chronology of glaciations in Africa for the past 100,000 years or more. We also plan to use cosmogenic nuclides to date paleolake shorelines from accessible locations where strand lines are well preserved and have appropriate surfaces to date. High resolution glacial and lake-level chronologies from these sensitive locations should provide important data relevant to understanding the factors controlling late Quaternary climates in equatorial and subtropical regions of Africa. The final goal of the proposed project is to synthesize the geochronological inf ormation obtained from the above sources into a coherent paleoclimatic record and to place this regional reconstruction in the context of global climate change in the late Quaternary. Our geological and paleoclimatic data collected in Africa will contribute to the construction of the global database of Pleistocene glaciations based on cosmogenic dating terrestrial deposits. The results will be valuable for researchers in the areas of Quaternary geology, geomorphology, glaciology, geochemistry, paleoclimatology, atmospheric sciences and hydrology. ??

小行星9632277 重建过去冰川和闭盆湖泊的时间和范围对于了解第四纪区域和全球气候变化至关重要。 热带地区，特别是赤道非洲地区，迫切需要这些数据，因为从陆地记录推断的古气候与使用大气环流模型计算的古气候之间存在相当大的差异。 建立高质量的陆地古气候数据库是古气候学研究的主要需求之一。 拟议的研究有助于满足这些需要，提供准确的日期，定量气候代用数据的气候敏感的地点在赤道和亚赤道非洲。 在西北亚热带高山地区（高阿特拉斯）和非洲中东部热带地区（肯尼亚和基利曼哈罗等），冰川沉积物已得到确认并绘制成图。 在这些位置，多个冰碛系统记录过去的冰川范围，并提供了以前的气候波动的重要代理。 由于缺乏与冰川沉积物相关的可测年材料，这些地貌中很少有被数字测年的。 因此，地方年表主要是基于地形之间的地层关系和相对风化的比较研究。 我们建议使用宇宙成因同位素测年方法（36Cl，10Be， 26Al，14C，21Ne和3He），以建立过去10万年或更长时间的非洲冰川年表。 我们还计划使用宇宙成因的核素，以日期古湖岸线从可访问的位置，在那里链线保存完好，并有适当的表面日期。 高分辨率的冰川和湖泊级年表，从这些敏感的位置应提供重要的数据，了解非洲赤道和亚热带地区的晚第四纪气候的控制因素。 该项目的最终目标是将从上述来源获得的地质年代学信息综合成一个连贯的古气候记录，并将这一区域重建置于晚第四纪全球气候变化的背景下。 我们在非洲收集的地质和古气候数据将有助于建立基于地球成因定年的更新世冰川全球数据库。 研究结果对第四纪地质学、地貌学、冰川学、地球化学、古气候学、大气科学和水文学等领域的研究人员具有重要的参考价值。 ??