Orbital tuning of paleoclimate geothermal reconstructions
A new method is presented to increase the dating accuracy of geothermal paleoclimate reconstructions. The method is based on a simultaneous inversion of surface paleotemperatures and changes of ground surface heat flux, and on a comparison of the latter with external radiative forcing variations on long time scales. The developed algorithm is similar to the method of orbital tuning used for isotope temperature chronologies, but has a substantial advantage: for the revision of reconstructed paleoclimate chronologies, two energy characteristics are compared. It promotes adequate accounting the delay of the temperature reaction to changes in external radiative forcing. The presented method works best for the long-period paleoclimate reconstructions (some tens of thousands of years long). The algorithm should be used carefully for the former glaciation regions. The method was tested using ground surface temperature history reconstructed in the Urals for the past 35 kyr. The applying of the orbital tuning of geothermal paleoclimate reconstructions made it possible to achieve the 99% correlation between the ground surface heat flux and insolation changes in time interval of 35-6 kyr BP staying within the natural variability of the thermophysical properties of the rocks.