Collaborative Research: RUI--Late Holocene Climate of the Central Andes Identified from Sedimentary, Stable Isotopic, Geochemical and Biological Proxies

该项目旨在从安第斯山脉中部南纬11度至20度的一系列湖泊中获取高分辨率的古气候记录，并将以尽可能高的时间分辨率（根据以前的工作，为5至20年）记录该区域湖泊的气候变化。由此产生的空间-时间数据集将提供有关整个区域干旱频率、强度和空间变异性的信息，该区域有数百万人生活在仅能维持生计的水平上，水资源有限，在冬季干旱季节，冰川和快速消退的冰川是重要的水源。从每个湖泊的沉积中心采集的沉积物芯将用于记录水文状况的变化通过测量介形虫壳或自生碳酸盐（如果有的话）或沉积物纤维素（基岩地质学不允许沉积物中自生碳酸钙的保存）的氧和碳同位素比率，可以确定沉积物中碳酸钙的含量。这些分析将得到从浅水到深水的岩心样带研究的补充，以确定湖泊水位的大规模变化并确定其日期。将使用稳定同位素质量平衡和水文状态的建模研究来量化结果。这项工作的结果将与环太平洋地区的其他古记录一起进行研究，以确定造成所观察到的变化的可能气候机制。特别是，将把结果与厄尔尼诺/南方涛动（ENSO）和太平洋十年期涛动（PDO）的长期记录进行比较。预计这一信息将有助于预测、准备和规划未来的干旱。

This project is designed to obtain high-resolution paleoclimate records from a series of lakes in the central Andes spanning latitudes 11 degrees south to 20 degrees south, and will document climatic variability at the highest possible temporal-resolution (5 to 20 years based on previous work) from lakes in this region. The resulting spatial-temporal dataset will provide information regarding drought frequency, intensity and spatial variability across a region where millions of people live at a subsistence level, limited water-resources, and rapidly retreating glaciers that currently supply an important source of water during the winter dry season.Sediment cores recovered from the center of deposition in of each lake will be used to document changes in the hydrologic status through time by measuring oxygen and carbon isotopic ratios on either ostracod shells or authigenic carbonate (where available), or sediment cellulose where the bedrock geology does not allow for the preservation of authigenic calcium carbonate in the sediments. These analyses will be augmented with core transect studies from shallow to deep water to identify and date large-scale variations in lake level. Results will be quantified using modeling studies of stable isotope mass balance and hydrologic status. The results arising from this work will be studied alongside other paleorecords from the Pacific Rim to identify the likely climatic mechanism(s) responsible for the observed changes. In particular, results will be compared with long records of the El Nino/Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). This information is expected to be helpful for forecasting, preparing and planning for future droughts.