多十年际尺度下系统建立140ka以来关键事件的石笋新精准时标

石笋古气候记录研究得以快速发展，一个重要原因是其拥有高精准的年龄。随着激光共聚焦显微镜和10^13Ω高阻放大器的应用，其相对和绝对年龄精度将被进一步地提高，石笋古气候研究也迎来了新的机遇。本项目拟将石笋的新铀系绝对时标与年层相对时标校准统一，结合川东北特定季风区的蕴含气候变化细节的大变幅氧同位素序列，标定出140ka以来关键气候事件的突变或转换过程的精准时标。以典型的Heinrich事件（如H4）、Dansgaard-Oeschger事件（如D-O15和D-O18）和Termination事件（T-I和T-II）等为核心，进一步校准格陵兰冰芯时标，系统地探索高、低纬关键气候事件的精准相位关系及动力学机制。在多十年际（绝对年龄）-年际（相对年龄）尺度下系统地构建起140ka以来以中国石笋记录为基础的古气候变化过程的新精准年代学框架，为全球古气候学研究提供新的关键数据。

Paleoclimate studies of speleothem records have advanced dramatically, largely because speleothem records can be precisely dated by U-Th technique. The recent developments at technical frontiers of laser scanning confocal microscopes and 10^13 Ohm high gain amplifier have made it practical to further improve speleothem relative chronology through the annual band counting and absolute chronology through new generation U-Th dating techniques. On the basis of combinations of aforementioned new techniques and a set of unique speleothem samples with high U content, annual band and large amplitude oxygen isotope variation from NE Sichuan province, China, this project aims to characterize timings and structures of a set of key climate events in the last 140 ka BP at multidecadal-annual precision level, including Heinrich events (e.g., H4), Dansgaard-Oeschger cycles (e.g., D-O15 and D-O18) and Terminations (T-I and T-II). The new data from this project will be critical not only for systematically calibrating the Greenland ice core chronology to an unprecedent precision level, but also for further exploring timings/phase-relations and the response/feedback dynamics between climate events occurred in various climate systems on multi-decadal (U-Th dating) to annual (lamina-counting) timescales.