Early Paleogene continental temperature patterns and gradients over eastern Eurasia

Abstract

Early Paleogene latitudinal continental temperature gradients along the Pacific coast of Eurasia are studied in time and space using the Coexistence Approach, for the first time applied on an extensive regional palaeobotanical record. The palaeobotanical data used in this reconstruction are compiled from literature resources on a total of 110 reasonably well-dated floras, including 79 palynofloras, 30 leaf floras and one carpoflora covering the early Paleocene (Danian) to early Eocene (Ypresian), i.e., a time-span of ca. 25 myr, in total. The palaeobotanical records originate from terrestrial deposits of 73 localities situated along the Pacific coast of Eurasia, including the Far East of Russia, Eastern Siberia, China, and Japan. Our results reveal very weak latitudinal temperature gradients during the early Paleogene. Nevertheless, based on mean values of mean annual temperature and cold month mean temperature, two different regional climatic zones can be distinguished in the Paleocene representing in each case the cooler and warmer (subtropical) part of warm temperate climate of the Koeppen-Geiger system. In the early Eocene, the gradient became more clearly pronounced and in addition, a cool temperate zone can be distinguished. The presence of mangroves in our early Eocene records, already known from previous studies, is largely in line with our climate reconstruction and possible can be related to hyperthermal events such as the PETM and ETM.