Trace element variations in coeval holocene speleothems from GB cave, southwest England

We report trace element (Mg, Sr and Ba) records based on laser ablation ind uctively coupled plasma mass spectrometry (LA-ICP-MS) from three coeval Hol ocene speleothems from Great Chamber in GB Cave, southwest England. The tra ce element records are placed on a common timescale on the basis of a suite of TIMS Th-230-U-234 ages. This permits assessment of the reproducibility of the trace element record in coeval speleothems. The tract element record s are not coherent, raising debuts over the reliability of individual trace element records as potential archives of palaeoenvironmental information. Mg/Sr in speleothem calcite has been proposed as a potential palaeothermome ter as Mg partitioning into calcite from water is temperature-dependent. wh ile Sr partitioning into calcite is temperature-independent. However, we pr esent the results of calculations which demonstrate that the observed Mg/Sr values in the three stalagmites cannot have been produced by Holocene temp erature changes alone and that other processes must play a dominant role. W e present a model which suggests that the observed trace element variations in the three speleothems reflect hydrological mixing of waters in the epik arstic zone above the cave which have interacted with two geochemically dis tinct source rocks (calcite and dolomite).