Heather M. Stoll1, Ana Moreno2, Ana Mendez-Vicente1, Saul Gonzalez-Lemos1, Montserrat Jimenez-Sanchez1, Maria Jose Dominguez-Cuesta1, R. Lawrence Edwards3, Hai Cheng3,4, Xianfeng Wang3
1Department of Geology, University of Oviedo, Oviedo 33005, Spain
2Instituto Pirenaico de Ecología (IPE)-CSIC, Avda. Montañana 1005, 50059 Zaragoza, Spain
3Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455, USA
4Institute of Global Environmental Change, Xian Jiaotong University, Xian 710049, China
Tóm tắt
Speleothem growth requires humid climates sufficiently warm to stimulate soil CO2 production by plants. We compile 283 U/Th dates on 21 stalagmites from six cave systems in the NW coast of Spain to evaluate if there are patterns in stalagmite growth that are evidence of climatic forcing. In the oldest stalagmites, from marine oxygen isotope stage (MIS) 7–5, growth persists through the glacial period. Hiatuses and major reductions in growth rate occur during extreme minima in summer insolation. Stalagmites active during the last interglaciation cease growth at the MIS 5–4 boundary (74 ka), when regional sea-surface temperature cooled significantly. During MIS 3, only two stalagmites grew; rates were highest between 50 and 60 ka during the maximum in summer insolation. One stalagmite grew briefly at 41 ka, 36.5 and 28.6 ka, all during warm phases of the Dansgaard–Oeschger cycles. A pronounced Holocene optimum in stalagmite growth occurs from 9 to 6 ka. The cessation of most growth by 4.1 ka, coincident with broad increases in aridity over the Mediterranean and areas influenced by the North African Monsoon, suggest that regions such as NW Spain, with dominant Atlantic moisture sources, also experienced increased aridity at this time.
