COLLABORATIVE: EAGER: Seismic Survey of Lake Junin, Peru in Preparation for Deep Drilling

这笔赠款将为计划中的朱宁湖(秘鲁)深井钻探提供关键的现场勘测信息。该团队将对朱宁湖进行气枪地震调查，以估计沉积物厚度，并提供选择最佳深井钻探地点所需的空间分辨率。这项工作将在很短的野外季节(~两周)内完成，结果将提供给国际大陆钻探计划(ICDP)钻探工作室。朱宁湖包含一个可能跨越多个冰川周期的沉积物记录--可能跨越数十万年，它包含的碳酸盐可以提供湖泊水文和区域气候的同位素记录，分辨率达到十年以下。跨越40年的众多教职员工和学生为关于该湖及其分水岭的广泛数据库做出了贡献。然而，朱宁湖从未在沉积最深的地区进行岩心取心，也从未配备过能够穿透湖中央厚厚沉积层序的机械取心器。ICDP科学顾问组同意朱宁湖确实值得进行深度钻探，并已出资高达4万美元举办了一次国内研讨会，为深度钻探项目发展科学团队。这次研讨会将在秘鲁举行，来自美国、加拿大、德国和其他ICDP国家的大约20多名科学家将聚集在一起。尽管ICDP科学顾问组表达了他们对朱宁湖潜在深部钻探的热情，但他们也指出，改善朱宁湖盆地的地震成像是批准ICDP钻探的先决条件。预期的结果包括对朱宁盆地湖相沉积物和夹层冰川沉积物的厚度和分布有更全面的了解，这将为选择合适的取心设备和钻探地点提供必要的指导，并将能够估计未来任何深部钻探项目需要处理的沉积物岩心长度。拟议工作的智力价值基于这样一个事实，即改进的朱宁湖地震调查是进行深部钻探的先决条件。这反过来将产生沉积岩芯，可以解决与第四纪晚期热带气候变化有关的几个基本问题。这些问题包括：1)热带地区最近几次冰川循环与两个半球高纬度地区冰川循环的同步度，2)间冰期和间冰期的水文气候稳定程度，3)间冰期期间ENSO的长期演变，4)温度和降水在控制热带安第斯山脉多个冰川、去冰期和间冰期冰川物质平衡中的相对作用。拟议的研究的更广泛意义将取决于朱宁湖深井钻探项目的成功开发。这样的项目将为培训众多本科生和研究生以及促进我们的秘鲁同事开展气候变化研究提供一个理想的平台。

This grant will generate critical site survey information for planned deep drilling of Lake Junin (Peru). The team will carry out an airgun seismic survey of Lake Junin in order to estimate the sediment thickness, and to provide the spatial resolution needed for selection of the best deep drilling sites. The work would be completed in a short (~two week) field season, with results made available for an International Continental Drilling Program (ICDP) drilling workshop.Lake Junin contains a sediment record that likely spans multiple glacial cycles?perhaps covering many hundreds of thousands of years, and it contains carbonates that can provide isotopic records of lake hydrology and regional climate with sub-decadal resolution. Numerous faculty and students spanning four decades have contributed to an extensive database on the lake and its watershed. However, Lake Junin has never been cored in its most deep sedimented areas, and has never been cored with a mechanical corer capable of penetrating the thick sedimentary sequences that lie under the center of the lake.The Scientific Advisory Group of the ICDP has agreed that Lake Junin is indeed worthy of a deep drilling effort, and has funded up to US $40,000 for an in-country workshop to develop a science team for a deep drilling project. This workshop, which will be held in Peru, will bring together about two dozen scientists from the U.S., Canada, Germany and other ICDP countries. Although the Scientific Advisory Group of ICDP has expressed their enthusiasm for potential deep drilling of Lake Junin, they have also noted that improved seismic imaging of the Lake Junin basin is a prerequisite for ICDP drilling approval.Expected results include a more complete understanding of the thickness and distribution of lacustrine sediment and intercalated glaciogenic sediment in the Junin basin, which will provide essential guidance for selection of appropriate coring equipment and drilling sites, and will enable estimates to be made of the length of sediment core that will need to be processed for any future deep drilling project.The intellectual merit of the proposed work is grounded in the fact that an improved seismic survey of Lake Junin is a prerequisite for deep drilling, which, in turn, will yield sediment cores that can address several fundamental issues regarding tropical climate change during the late Quaternary. These include: 1) the degree of synchrony between the last several glacial cycles in the tropics and those in higher latitude regions of both hemispheres, 2) the degree of hydroclimatic stability that prevailed during interglacial and interstadial intervals, 3) the long-term evolution of ENSO during interglacial intervals, and 4) the relative roles of temperature and precipitation in governing glacier mass balances in the tropical Andes over multiple glacial, deglacial, and interglacial intervals.The broader significance of the proposed research will depend on the successful development of a deep drilling project on Lake Junin. Such a project would provide an ideal platform for training numerous undergraduate and graduate students, and for promoting climate change research by our Peruvian colleagues.