Paleoclimate Variability Recorded in Varved Sediments of Lake Malawi, Tropical Africa

题目：热带非洲马拉维湖沉积沉积物的古气候变化记录该奖项支持从马拉维湖北部四个地点收集沉积物岩心，以建立跨越整个全新世的过去气候变化的可靠、高分辨率记录。岩心将通过Pb-210、AMS C-14和阀门计数来确定年代。将分析沉积物的重量百分比生物二氧化硅和阀门的浅色和深色层厚度。生物成因硅丰度反映了初级生产力，这是上升流强度的函数，与风力强度和季节冷却有关。对联的轻层是硅藻泥，也反映了干风季节（6 - 8月）的初级生产力。深色层由陆源粉砂和粘土与硅藻混合物组成。这反映了南方夏季雨季（12月- 3月）河流径流的强度。薄片厚度记录（光层组合）将进行演化光谱分析，特别关注全新世enso尺度的变化。对沉积物的初步研究将包括氧化还原敏感元素分析、有机质同位素组成和硅藻组合组成。这项研究将与世界银行资助的马拉维全球环境基金（GEF）项目合作，该项目将提供船舶时间、在该国的后勤支持以及沉积物的Pb-210分析。这将是一项与马拉维、加拿大和挪威科学家的合作。对马拉维湖的古气候学调查将作为东非湖泊国际十年（IDEAL）的一部分进行。IDEAL是一个多学科、多国的研究和培训项目，主要研究东非的大型湖泊。

Abstract ATM-9709291 University of Minnesota Johnson, Thomas C. Title: Paleoclimate Variability Recorded in Varved Sediments of Lake Malawi, Tropical Africa The award supports the collection of sediment cores from four sites in northern Lake Malawi, to establish a robust, high-solution record of past climate change that spans the entire Holocene. The cores will be dated by Pb-210, AMS C-14, and varve counts. The sediments will be analyzed for weight per cent biogenic silica and for light and dark layer thickness of the varves. Biogenic silica abundance is believed to reflect primary productivity, which is a function of upwelling intensity, related to wind strength and seasonal cooling. The light layers in the varve couplets are diatom ooze, also reflecting primary productivity during the dry windy season (June - August). The dark layers consist of terrigenous silts and clays with admixtures of diatoms. These reflect the intensity of river runoff during the rainy season in the austral summer (Dec. - March). The varve thickness records (light layer, combined) will be subjected to evolutionary spectral analysis, paying particular attention to ENSO-scale variability through the Holocene. Pilot studies on the sediments will include redox-sensitive elemental analysis, organic matter isotopic composition, and diatom assemblage composition. This research will be in collaboration with the Malawi Global Environment Facility (GEF) program funded by the World Bank, which will provide ship time, logistical support in the country, and Pb-210 analyses of the sediments. This will be a collaborative effort with scientists from Malawi, Canada and Norway. This paleoclimatological investigation on Lake Malawi will be conducted as part of the International Decade for the East African Lakes (IDEAL). IDEAL is a multi-disciplinary, multinational program of research and training on the large lakes of East Africa.