One and a half million yearlong aridity during the middle Eocene in north-west China linked to a global cooling episode

Here we present new paleoclimate data from the Eocene red clay sequence deposited between 40 and 50 Ma in Altun Shan at the northeastern edge of the Tibetan Plateau. After building an age model using a compilation of magnetostratigraphy and cyclostratigraphy, we demonstrate that our record of magnetic susceptibility in the Altun Shan red clay exhibits variations linked to eccentricity cycles. Our age model allows us to estimate the age of eight short geomagnetic events, cryprochrons, in Altun Shan. Further we show that the aridification interval in Altun Shan coincides with (i) a cooling event recorded in the global oxygen isotope record, (ii) a sea surface temperature record on the east Tasmanian plateau, and (iii) an aridity record in the surrounding sedimentary basins of Central Asia. The middle Eocene aridity and cooling reached its maximum 45.5-44 Ma.