Southward shift of the Intertropical Convergence Zone due to Northern Hemisphere cooling at the Oligocene-Miocene boundary
Kiseong Hyeong et al. (Boo-Keun Khim [corresponding]), Korea Institute of Ocean Science and Technology, 878 Haean-ro, Ansan 426-744, Republic of Korea (Khim: Dept. of Oceanography, Pusan National University, Busan 609-735, Republic of Korea). Published online 9 June 2014; http://dx.doi.org/10.1130/G35664.1.
The Mi-1 glaciation (approx. 23 million years ago), which marks the OligoceneMiocene boundary, was an aberrant cooling event that led to a build-up of Antarctic ice sheet reaching the near-modern volume or larger from its ephemeral or partial existence. In contrast, Northern Hemisphere (NH) glaciation has not been considered as a consequence of the event due to lack of definitive evidence. Here, we investigated the inter-hemispheric temperature contrast during Mi-1, by tracing the movement of the tropical maximum rainfall belt (TMRB) at a site (1031'N) in the East Pacific (IODP Site U1333), to understand NH cooling and possibility of NH glaciation. Our dust data indicate the southward displacement of the TMRB over Site U1333 during Mi-1 (~4N at the Oligocene-Miocene boundary). The TMRB shifts toward the warmer hemisphere.
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Geological Society of America