Planning: CDP: High-Resolution Seismic Reflection Site Survey Supporting Lake Victoria Scientific Drilling

2231128奖学金该奖项将支持从东非维多利亚湖获取高分辨率地震反射数据。为了对盆地湖泊沉积的地下结构和地层格架进行成像，在两年内提出了几条地震线(2000公里)。其目的是确定该湖的最佳钻探区域，作为未来计划的一部分，该建议旨在钻探湖泊沉积物并恢复长期和连续的沉积记录，以促进对该地区和湖泊生物的区域更新世/全新世古气候学、古环境和生物史的研究。一台啁啾地震反射仪将由一艘承包的船只拖曳。收集的数据将被处理、分析和解释，使用旧技术在1980年代和90年代收集的遗留地震反射数据将被重新处理，数据集被整合并最终存档在Lamont Doherty地球观测站的海洋地球科学数据系统(MGDS)中。规划活动和拟议的地震调查需要制定未来的竞争性提案，以便在维多利亚湖上开展科学的湖泊钻探活动。这些PI是一个国际科学家团队的一部分，该团队已经得到了国际大陆科学钻探计划的支持，将于2022年夏天在坦桑尼亚主办一个规划研讨会。拟议的工作将成为锡拉丘兹大学一名坦桑尼亚国民研究生论文工作的基础，这项工作将与坦桑尼亚机构合作进行，包括渔业部、地质调查局和达累斯萨拉姆大学。维多利亚湖是非洲最大的湖泊，是白尼罗河的源头，是数百种特有生物的家园，支持着地球上最大的湖泊渔业，包含着热带大陆第四纪气候变化的重要记录。由于其浅水、宽广的形态和较大的表面积与集水比，该湖对水气候的变化极其敏感。该湖水位的波动是该湖动植物范围扩大、收缩、碎片化、适应和多样化的重要驱动因素，以及更广泛的分水岭，并促进了早期智人种群在非洲各地的扩散。先前对湖泊沉积岩心和地震反射数据的研究记录了该湖在更新世末期几乎完全干燥，该湖分水岭内的陆地露头和来自湖内的地震数据表明，该湖在其大约40万年(约400 Kyr)的历史中可能经历了多次干燥和再灌水。未来的钻探计划将支持对一系列专题的研究，包括1)湖盆的形成和发展，2)热带气候和多个冰川-间冰期周期的环境变化，3)与湖泊干旱事件的气候联系，4)水生动物对湖泊动态和气候变化的响应，5)与湖泊范围相关的气候和环境压力，以及6)稀树草原生态系统变化及其生物地理影响。然而，从湖中获得的传统地震反射数据并不适合从盆地中选择科学钻探岩心，这项提议将获得现代的、高分辨率的海洋类型的啁啾地震反射数据，这些数据将通过整个盆地存在的有据可查的晚更新世不整合来成像。这一奖励反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

2231128ScholzThis award will support acquisition of high-resolution seismic reflection data from Lake Victoria in East Africa. Several seismic lines are proposed (2000 km) over a two-year period in order to image the subsurface structure and stratigraphic framework of basinal lake sediments. The intent is to determine the best areas of the lake to drill as part of a future planned proposal to drill into lake sediment and recover long and continuous sedimentary records to facilitate studies of regional Pleistocene/Holocene paleoclimatology, paleoenvironments, and biologic history of the region and lake organisms. A CHIRP seismic reflection instrument would be towed by a contracted vessel. The data collected would be processed, analyzed, and interpreted and legacy seismic reflection data collected in the 1980 and 90s using older technology would be reprocessed, the data sets integrated and ultimately archived within the Marine Geoscience Data System (MGDS) at Lamont Doherty Earth Observatory. Planning activities and proposed seismic surveys are required to develop a future competitive proposal to conduct a scientific lake drilling campaign on Lake Victoria. The PIs are part of an international team of scientists who have already been supported by the International Continental Scientific Drilling Program to host a planning workshop in Tanzania in summer 2022. The proposed work would form the basis for the thesis work of an incoming Syracuse University graduate student who is a Tanzanian national and the work would be conducted in collaboration with Tanzanian institutions, including the Department of Fisheries, the Geological Survey Department, and the University of Dar es Salaam. Lake Victoria is the largest lake in Africa, is the source of the White Nile, is home to hundreds of endemic organisms, supports the largest lake fishery on Earth and contains important records of Quaternary climate variability in the continental tropics. Given its shallow, broad morphometry and large surface area- to- catchment ratio, the lake is extremely sensitive to changes in hydroclimate. Fluctuations in the water levels of the lake are important drivers for range expansion, contraction, fragmentation, adaptation, and diversification for flora and fauna in the lake (e.g., cichlid fish), as well as the broader watershed, and have contributed to the dispersal of early populations of Homo sapiens across Africa. Prior studies of lake sediment cores and seismic reflection data document the virtually complete desiccation of the lake at the terminal Pleistocene, and terrestrial outcrops within the lake’s watershed and seismic data from within the lake suggest the lake has likely desiccated and refilled multiple times in its approximately 400,000- year (~400 kyr) history. A future drilling program would support research on an array of topics, including 1) lacustrine basin formation and development, 2) tropical climate and environmental change over multiple glacial-interglacial cycles, 3) climate linkages to lake desiccation events, 4) diversification and evolution of aquatic fauna responding to lake dynamics and climate change, 5) climate and environmental pressures associated with lake extent driving dispersal of early human populations, and 6) savanna ecosystem changes and their biogeographic implications. The legacy seismic reflection data available from the lake are not suitable however for siting scientific drill cores from the basin, and this proposal will acquire modern, high- resolution ‘marine-type’ CHIRP seismic reflection data, which will image through the well-documented late Pleistocene unconformity present across the basin.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.