1.2-million-year band of Earth--Mars obliquity modulation on the
evolution of cold late Miocene to warm early Pliocene climate
Abstract
The climatic transitions during the Miocene–Pliocene epochs had
significant impacts on the worldwide biological diversity and were
associated with large turnovers of continental vegetation and fauna.
Previous studies have shown that late Miocene cooling and continental
aridification which was initiated 7 Ma reversed to warm conditions
across the Miocene–Pliocene Boundary ~ 5.3 Ma. Here we
present detailed orbital pacing of Asian monsoon deposits to constrain
further the global climate change during this period. We produce
high-resolution magnetic susceptibility records which reveal that the
1.2 Myr obliquity modulation would have been the main driving factor of
the cooling and warming that occurred ~ 7 Ma and 5.3 Ma,
respectively. The Tibetan rise and closures of the Panama and Indonesian
seaways enhanced the impact of the 405 kyr eccentricity cycles to an
oscillatory climatic state while the Northern Hemisphere glaciations
were increasing from 4 to 2.5 Ma.