Southward shift of the Intertropical Convergence Zone due to Northern Hemisphere cooling at the Oligocene-Miocene boundary

Research Article| August 01, 2014 Southward shift of the Intertropical Convergence Zone due to Northern Hemisphere cooling at the Oligocene-Miocene boundary Kiseong Hyeong; Kiseong Hyeong 1Korea Institute of Ocean Science and Technology, 787 Haean-ro, Ansan 426-744, Republic of Korea Search for other works by this author on: GSW Google Scholar Jongmin Lee; Jongmin Lee 2Department of Oceanography, Pusan National University, Busan 609-735, Republic of Korea Search for other works by this author on: GSW Google Scholar Inah Seo; Inah Seo 1Korea Institute of Ocean Science and Technology, 787 Haean-ro, Ansan 426-744, Republic of Korea3School of Earth and Environmental Sciences, Seoul National University, Seoul 151-747, Republic of Korea Search for other works by this author on: GSW Google Scholar Mi Jung Lee; Mi Jung Lee 4Korea Polar Research Institute, 26 Songdomirae-ro, Incheon 406-840, Republic of Korea Search for other works by this author on: GSW Google Scholar Chan Min Yoo; Chan Min Yoo 1Korea Institute of Ocean Science and Technology, 787 Haean-ro, Ansan 426-744, Republic of Korea Search for other works by this author on: GSW Google Scholar Boo-Keun Khim Boo-Keun Khim * 2Department of Oceanography, Pusan National University, Busan 609-735, Republic of Korea *E-mail: bkkhim@pusan.ac.kr. Search for other works by this author on: GSW Google Scholar Geology (2014) 42 (8): 667–670. https://doi.org/10.1130/G35664.1 Article history received: 11 Mar 2014 rev-recd: 16 May 2014 accepted: 17 May 2014 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Kiseong Hyeong, Jongmin Lee, Inah Seo, Mi Jung Lee, Chan Min Yoo, Boo-Keun Khim; Southward shift of the Intertropical Convergence Zone due to Northern Hemisphere cooling at the Oligocene-Miocene boundary. Geology 2014;; 42 (8): 667–670. doi: https://doi.org/10.1130/G35664.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The Mi-1 glaciation (ca. 23 Ma), which marks the Oligocene-Miocene boundary, was an aberrant cooling event that led to a build-up of the Antarctic ice sheet, which reached the near-modern volume (or greater) from its ephemeral or partial existence. An increase of ∼1‰ in the δ18O of benthic foraminifera during this interval has been attributed to the development of Antarctic ice sheets and deep-water cooling. Without definitive evidence, Northern Hemisphere (NH) glaciation has not been a material consideration for the δ18O increase. Here we investigate the interhemispheric temperature contrast during Mi-1, with the movement of the Intertropical Convergence Zone (ITCZ) at a site (10°31′N) in the East Pacific (Integrated Ocean Drilling Program Site U1333), to understand NH cooling and the possibility of NH glaciation. The measured 143Nd/144Nd, 87Sr/86Sr, and clay mineral compositions of eolian dust fractions indicate unequivocally the deposition of Asian dust during Mi-1, and of Central American and South American dust before and after Mi-1. This is attributed to the southward displacement of the ITCZ over Site U1333 during Mi-1. The ITCZ shifts toward the warmer hemisphere. Thus our results suggest that the cooling during Mi-1 was more significant in the NH than in the Southern Hemisphere, which underwent a sudden expansion of continental ice sheets. Our data call for a forcing mechanism to drive significant NH cooling during this episode. Based on the available data, we propose that the widespread growth of NH ice sheets and/or changes in the production of North Atlantic–origin deep water could be possible causes of the NH cooling at that time. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.