(GRGC) Collaborative Research: High Resolution Glacial Geologic & Palynologic Records of the Last Deglaciation in the Tropical Andes

9422424塞尔策拟议项目的主要目标是从热带安第斯山脉的四个地区的湖泊沉积岩芯中获得连续的、高分辨率的14C可测定的冰川和植被变化的替代记录，这些岩芯跨越了最后一次冰川消退和全新世，在这些地区已经有证据表明在最后一次冰川向间冰期转变期间气候突然逆转。PIS不仅试图改进热带安第斯山脉晚冰期气候振荡的年代学，而且还寻求改善解释沉积学和孢粉学记录的基础。具体地说，PIS建议：i)将冰川地质学和冰湖沉积学结合起来，以估计上一次冰川消融期间冰川平衡线高度变化的时间、速度和幅度；ii)将现代植被研究与亚马逊盆地西部沉积物岩心的孢粉学分析结合起来，以估计该地区最后一次冰川向间冰期转变标志着植被突然变化的时间和古气候因素，三)与厄瓜多尔地质学家合作，确定在最后一次冰川消融期间沉积的地球化学显眼的冰盖单元的年代和特征，以便这些重要的等时线可用于在热带安第斯山脉不同地点的沉积物和冰芯中保存的古气候替代记录之间精确关联，以及四)根据初步和公布的放射性碳年龄，对特定冰雹提供更严格的年龄限制，这些冰雹大约与YD事件和H1事件同时沉积。

9422424 Seltzer The primary objective of the proposed project is to obtain continuous, high-resolution, AMS 14C datable proxy records of glaciation and vegetation change from lacustrine sediment cores that span the last deglaciation and Holocene from four regions in the tropical Andes where evidence for abrupt climatic reversals during the last glacial-to-interglacial transition have already been documented. The PIs seek to improve not only the chronology of late-glacial climatic oscillations in the tropical Andes but also to improve the basis for interpreting the sedimentologic and palynologic records. Specifically, the PIs propose: i) to couple glacial geology and glacial-lacustrine sedimentology to provide estimates for the timing , rate, and magnitude of changes in glacier equilibrium -line altitudes during the last deglaciation, ii) to couple modern vegetation studies with palynological analyses of sediment cores from the western Amazon Basin to estimate the timing of and paleoclimatic factors responsible for the abrupt changes in vegetation that marked the last glacial-to-interglacial transition in this region, iii) to collaborate with Ecuadorian geologists to date and characterize geochemically conspicuous tephra units that were deposited during the last deglaciation so that these important isochrons may be used to correlate precisely among proxy records of paleoclimate preserved in sediment and ice cores from different sites in the tropical Andes, and iv) to provide closer age constraints for specific moraines, which, based on both preliminary and published radiocarbon ages, were deposited at about the same time as the YD and H1 Events.