Home – Home – Jornals – Russian Geology and Geophysics 2006 number 1

The Earth has lived through three major climate periods: the Archean period when no glaciation appeared on the hot Earth, the Late Archean-Middle Riphean period of occasional glacial spells, and the period of rhythmic glacials from the Late Riphean to Present. The general climate trend was controlled by gradual cooling of the Earth's surface, and alternation of cold and warm cycles was influenced by volcanism. Eruptions along convergence plate boundaries provoked glacial events while pulses of within-plate magmatism corresponded to warm times. More control, especially during cold cycles, came from the position of continents and the presence of large continental mountain systems which governed the circulation of air and oceanic currents and the scale of chemical weathering. Finally, the most regular climate periodicity has been due to orbital forcing (Milankovitch cycles).
The Late Cenozoic climate events in Asia were mostly related to mountain growth in the zone of the India/Eurasia collision. The earliest strong cooling in the Northern Hemisphere at 2.8-2.5 Ma fits the time when the Tibetan Plateau shaped up in its present form and numerous ridges rose in Central Asia. The Late Cenozoic mountain building in South and Central Asia covered a total area exceeding 9 · 10⁶ km².
The Central Asian climate for the past 3 Myr was controlled by orbital forcing and changed in Milankovitch cycles (glacials and interglacials). The climate events in the Baikal record match the glacials and interglacials corresponding to pulses of flood-basalt magmatism in the mountains around Lake Baikal. Volcanics coeval to cold periods bear signature of eruption upon glaciers, i.e., all cold events recorded in the Baikal climate archive for the past 1.8 Myr were accompanied by mountain glaciation. The Brunhes chron included at least eight such glacials.