NOAA/WDS Paleoclimatology - Holzkaemper et al. 2009 Wolkberg Cave Stable Isotope Data

Little is known about the sequence of climate and environmental change in southern Africa during the last glacial period, in spite of the intimations from records, such as Antarctic ice cores and archaeological sites, that very marked changes took place which would have had profound effects on vegetation and animal distributions across the sub-continent. High-resolution, (semi-) continuous climate and environmental records can be extracted from suitable cave speleothems. Speleothems are reasonably abundant in southern Africa, but their occurrence is patchy in time and space and the records can be difficult to interpret. Here we report our assessment of the stalagmite W5 from Wolkberg Cave in the northeastern part of South Africa, as an archive for glacial-period climatic and environmental shifts. The cave is located at 1450 m asl, in the dolomitic limestones of the Transvaal System in an area currently dominated by C4 grass vegetation. Nine U/Th dates show growth from 58 to 46 ka, and a second brief phase ca. 40 ka, indicating that the availablemoisture was sufficient to allow speleothems to form. The d18O and d13C values along the growth axis show variability in the order of 2 per mil for the former, while variability in the latter is characterized by a shift from values near -2 per mil in the older section to +2 per mil or more in the younger part. These high d13C values are probably the combined result of CO2 degassing of the percolating soil water prior to the carbonate precipitation in the cave chamber, the increasing dominance of C4 over C3 vegetation, and the high percentage of aragonite towards the stalagmite's top. The retrieved data point towards increasingly drier and colder conditions during the growth period of the stalagmite. Furthermore, the high-frequency variations of d18O values indicate the presence of short term climate oscillations that are probably linked to shifts of the Intertropical Convergence Zone.

本存档的古气候学（Paleoclimatology）研究数据集，可通过美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）下属的国家环境信息中心（National Centers for Environmental Information, NCEI）的古气候学世界数据服务（World Data Service for Paleoclimatology, WDS）获取。该研究对应的NCEI研究类型为洞穴类（Cave）。数据集包含洞穴碳酸盐沉积（speleothems）的相关参数，其地理位置位于非洲南部的南非地区，时间覆盖范围为57880至39750个距今日历年份（Before Present, BP）。如需了解参数与研究地点的详细信息，请查阅元数据（metadata）。使用本数据集时，请引用该项研究。