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

该项目旨在获取安第斯山脉中部一系列湖泊的高分辨率古气候记录，这些湖泊横跨南纬11度至20度，并将记录该区域湖泊以尽可能高的时间分辨率(根据以前的工作为5至20年)进行的气候变化。由此产生的时空数据集将提供该地区干旱频率、强度和空间变异性的信息，该地区数百万人生活在生计水平上，水资源有限，冰川迅速消退，目前冰川是冬季干旱季节的重要水源。从每个湖泊的沉积中心恢复的沉积岩芯将被用来通过测量介形类贝壳或自生碳酸盐(如果有)或沉积物纤维素上的氧和碳同位素比率来记录水文状态随时间的变化，在基岩地质不允许保存沉积物中自生碳酸钙的情况下。这些分析将通过从浅水到深水的岩心横断面研究来加强，以确定湖泊水位的大范围变化并确定其日期。结果将通过对稳定同位素质量平衡和水文状况的模拟研究来量化。这项工作的结果将与来自环太平洋的其他古记录一起研究，以确定导致所观察到的变化的可能的气候机制(S)。特别是，结果将与厄尔尼诺/南方涛动(ENSO)和太平洋年代际涛动(PDO)的长期记录进行比较。预计这些信息将有助于预测、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.