Paleogene climate dynamics in the Primorye Region, Far East of Russia, based on a Coexistence Approach analysis of palaeobotanical data

Abstract

The Paleogene climate dynamics in Primorye (Far East of Russia) are studied using the Coexistence Approach, based on palaeobotanical records. Palaeobotanical data for the reconstruction comprises 54 palaeofloras covering the early Paleocene to late Oligocene, a time span of ca. 42 myr. The climate inferences obtained are consistent with independently derived global trends, demonstrating general climate cooling through the Paleogene. Cooling is most striking regarding the cold month mean temperature, while the decline of mean annual temperature was less marked. Our data indicate that the Paleogene climate of Primorye was significantly warmer than present, in general, with the warmest conditions prevailing throughout the Eocene and in the southeast of the study area. Negligible Paleogene temperature gradients over Primorye are related to the global pattern and specific regional aspects. The precipitation reconstruction points to conditions considerably wetter than at present. A distinct increase in mean annual precipitation is observed for the early Eocene and persisted throughout the Eocene and Oligocene. The regional rainfall pattern fundamentally differed from modern conditions, and this holds for all studied variables. The inland region and the south of Primorye were significantly more humid than today. The Paleogene pattern was possibly related to a monsoon-type circulation and enhanced landward flow of humid air masses, due to an overall flatter geomorphology of the East Asian coastal areas.