NOAA/WDS Paleoclimatology - Chiflonkhakha Cave, Umajalanta Cave Geochemical Data from 1300 to 78 Cal Yr BP

Here we present high-resolution δ18O records obtained from speleothems collected in the eastern Bolivian Andes. The stable isotope records are related to the regional- to large-scale atmospheric circulation over South America and allow interpreting changes in δ18O during the last 1400 yr as a function of changes in precipitation regimes over the southern tropical Andes. Two distinct phases with more negative δ18O values, interpreted as periods of increased convective activity over the eastern Andean Cordillera in Bolivia are observed concomitantly with periods of global climate anomalies during the last millennium, such as the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) respectively. Changes in the Bolivian δ18O record during the LIA are apparently related to a southward displacement of the Intertropical Convergence Zone (ITCZ), which acts as a main moisture driver to intensify convection over the tropical continent. During the MCA, however, the increased convective activity observed in the Bolivian record is likely the result of a different mechanism, which implies moisture sourced mainly from the southern tropical Atlantic. This interpretation is consistent with paleoclimate records further to the north in the tropical Andes that show progressively drier conditions during this time period, indicating a more northerly position of the ITCZ. The transition period between the MCA and the LIA shows a slight tendency toward increased δ18O values, indicating weakened convective activity. Our results also reveal a non-stationary anti-phased behavior between the δ18O reconstructions from Bolivia and northeastern Brazil that confirms a continental-scale east–west teleconnection across South America during the LIA.

本存档的古气候学研究数据集可由美国国家海洋和大气管理局（NOAA）国家环境信息中心（NCEI）通过古气候学世界数据服务（WDS）获取。该数据集关联的NCEI研究分类为洞穴（Cave）。本次数据集涵盖玻利维亚境内的洞穴沉积物（speleothems）相关参数。时间覆盖范围为距今1329至86个日历年（BP）。有关参数与研究地点的详细信息，请参阅元数据（metadata）说明。使用本数据集时，请引用该研究。