Northeastern Kalimantan hydroclimate of Core SO217-18522 over 50 kyrs@en

Changes in convective activity and hydroclimate over Northeastern Kalimantan are key features to understand glacial to interglacial climate evolution in the center of the West Pacific Warm Pool during the Late Pleistocene to Holocene. We use high-resolution X-ray fluorescence (XRF)-scanner derived elemental ratios in sediment Core SO217-18522 (1º 24.106' N, 119º 4.701'E, 975 m water depth) recovered from the northern Makassar Strait to reconstruct changes in precipitation-related weathering and erosion over Northeastern Kalimantan over the last 50 kyr. Enhanced seasonality of rainfall and an extended dry season during Heinrich Stadials (HS4 to HS1) and the Younger Dryas (YD) suggest weakening of the tropical convection associated with a southward shift of the tropical rain belt and the annual mean position of the Intertropical Tropical Convection Zone. Increasing sediment discharge and intensification of convective activity occurred during the early to mid-Holocene during an interval of high Northern Hemisphere insolation, elevated atmospheric pCO2 levels and global warming. Our reconstructions in comparison with regional terrestrial and marine records highlight the high spatial variability of Kalimantan hydroclimate on millennial to glacial-interglacial timescales.加里曼丹东北部对流活动与水文气候的变化，是解析晚更新世至全新世时期西太平洋暖池核心区冰期-间冰期气候演化过程的关键特征。本研究利用从望加锡海峡北部获取的沉积物岩芯SO217-18522（北纬1°24.106′，东经119°4.701′，水深975米）中，经高分辨率X射线荧光（X-ray fluorescence, XRF）扫描提取的元素比值，重建过去5万年以来加里曼丹东北部与降水相关的风化与侵蚀过程变化。在海因里希冷期（HS4至HS1）与新仙女木事件（Younger Dryas, YD）期间，降雨季节性增强且旱季延长，这表明热带对流活动减弱，对应热带雨带与热带辐合带年均位置向南偏移。在早全新世至中全新世时期，伴随北半球日照量升高、大气二氧化碳分压（pCO2）上升与全球变暖，沉积物通量增加且对流活动增强。本研究重建结果与区域陆地及海洋记录对比后表明，在千年尺度至冰期-间冰期尺度上，加里曼丹岛水文气候具有显著的空间异质性。