Solar influence and hydrological variability during the Holocene from a speleothem annual record (Molinos Cave, NE Spain)

We present a multi-proxy approach to reconstructing Holocene climate conditions in northeastern Spain based on an excellent correlation among the lamina thickness, colour parameters and isotope (O-18 and C-13) variations recorded in a speleothem. An age model constructed from five U/Th dates and annual lamina counting suggests that the uppermost 14.7cm of the MO-7 stalagmite grew between 7.2 and 2.5ka before present but experienced a growth hiatus from 4.9 to 4.3ka. Three spectral analysis methods were applied to 11 time series. The results reveal common solar periodicities on decennial (Gleissberg cycle) and centennial (De Vries-Suess cycle) scales. The onset of Holocene carbonate precipitation in the MO-7 stalagmite appears to be associated with a cold, wet period, whereas the hiatus and the end of growth are related to warm, dry periods. This environmental trend fits well within the regional Holocene climate.