Calibration of the speleothem delta function: an absolute temperature record for the Holocene in northern Norway

The speleothem delta function (SDF) provides a new transfer function between the d 18 O signal of speleothem calcite and surface ground temperature. The function is based on physical principles, relating d 18 O of the calcite to thermodynamic fractionation, and to the dripwater function, which in turn relates d 18 O of dripwaters to that of the local precipitation and thus to the modification of source water in relationship to the geographical position of the site. The SDF must be calibrated against at least two reliable and well-dated palaeotemperature points. The end product is a reconstruction of absolute cave and surface temperatures. The technique is tested using a Holocene speleothem from north Norway, SG93, dated by 12 TIMS U-Th dates. The reconstructed temperature curve is presented and compared with the GISP2 ice-core record and with the historic record. In both cases the correlation with SG93 is impressive, indicating the validity of the technique.