Paleocene and Eocene floristic and climatic change in Russia and Northern Kazakhstan

 

Authors: Akhmetiev MA

Published in: Bulletin of Geosciences, volume 85, issue 1; pages: 77 - 94; Received 6 May 2009; Accepted in revised form 5 October 2009; Online 8 January 2010

Keywords: flora, palaeoclimate, Paleocene, Eocene, Russia,

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Abstract

Paleocene and Eocene floras of Russia and adjacent regions are reviewed with an interpretation of climatic conditions under which they developed. Floristic and climatic changes in western and central regions of Russia in the Paleocene and in the first part of the Eocene were caused by the dynamics and rearrangement of the systems of marine seaways: a longitudinal seaway, which connected the Arctic basin with the marginal seas of Northern Peri-Tethys (Turanian, South Russian and others), and a latitudinal seaway, which connected the marginal seas of Northern Peri-Tethys with the Atlantic Ocean. As these systems were progressively reduced, the climate in the middle latitudes changed from paratropical (like in West and Central Europe) to a subtropical monsoon climate with wet summers (Late Ypresian to Lutetian), and later to a climate with wet winters (Late Lutetian to the first part of the Priabonian). Floristic changes reflect these climatic trends. In the Paleogene, cold currents constantly influenced the climate of regions of the northwestern Pacific and facilitated development of a warm-temperate mesophilic flora. A warmer episode took place in the Early Eocene. At this time thermophilic plants (Sabal, Myrtaceae and Lauraceae) reached Koryakia, North Western Kamchatka, probably as a result of northward migration. Some subtropical plants existed near the Recent Polar circle. The subtropicalRaichikha-type Flora lost temperate elements and, by ecological and climatic types, it is more similar to the Recent flora of South-West and South China.