The middle Miocene climatic transition; East Antarctic ice sheet development, deep ocean circulation and global carbon cycling

Author(s): Flower, Benjamin P.; Kennett, James P.
Author Affiliation(s): Primary:
University of California, Santa Barbara, CA, United States
University of Tsukuba, Japan
Volume Title: Cenozoic climate and paleogeographic changes in the Pacific region
Volume Author(s): Cronin, T. M., editor; Ogasawara, K.; Wolfe, J. A.
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, 108(3-4), p.537-555; 29th international geological congress on Cenozoic climate and paleogeographic changes in the Pacific region, Kyoto, Japan, Aug.24-Sept.3, 1992, edited by T. M. Cronin, K. Ogasawara and J. A. Wolfe. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. 148 refs.; illus.
Summary: The middle Miocene represents a major change in state in Cenozoic climatic evolution, following the climax of Neogene warmth in the late early Miocene at ∼16 Ma. The early stage of this climatic transition from ∼16 to 14.8 Ma was marked by major short term variations in global climates, East Antarctic Ice Sheet (EAIS) volume, sea level, and deep ocean circulation. In the later stage from ∼14.8 to 12.9 Ma, climatic developments included major growth of the EAIS and associated Antarctic cooling, a distinct increase in the meridional temperature gradient, large fluctuations in sea level followed by a global sea level fall, and important changes in deep water circulation, including increased production of Southern Component Water. East Antarctic ice sheet growth and polar cooling also had large effects on global carbon cycling and on the terrestrial biosphere, including aridification of mid-latitude continental regions. Increased stability of the EAIS after 14.8 Ma represents a crucial step in the establishment of late Neogene global climate systems. What controlled these changes in polar climates and the East Antarctic ice sheet? Deep ocean circulation changes probably played a major role in the evolution and variation in polar climates, as they have throughout the Cenozoic. Oxygen and carbon isotopic evidence for warm, saline deep water production in the eastern Tethyan/northern Indian Ocean indicates that meridional heat transport to the Antarctic inhibited Cenozoic polar cooling and EAIS growth during the early middle Miocene from ∼16 to ∼14.8 Ma. Inferred competition between warm low-latitude sources (derived from the eastern Tethyan-northern Indian Ocean) and a cold high-latitude source (Southern Component Water) from ∼16 to 14.8 Ma may have been associated with instability in the Antarctic climate and cryosphere. Reduction of warm, saline deep water flow to the Southern Ocean at ∼14.8 Ma may have decreased meridional heat transport to the Antarctic, cooling the region and leading to increased production of Southern Component Water. These middle Miocene climatic and cryospheric changes in the Antarctic had profound effects on marine and terrestrial climates. As the meridional surface temperature gradient increased, boundaries between climatic zones strengthened, leading to increased aridification of mid-latitude continental regions in Australia, Africa and North and South America, enhancing the development of grasslands and stimulating the evolution of grazing mammals.
Year of Publication: 1994
Research Program: DSDP Deep Sea Drilling Project
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Antarctic ice sheet; Antarctica; Assemblages; C-13/C-12; Carbon; Cenozoic; Changes; Deposition; East Antarctic ice sheet; Foraminifera; Geochemical cycle; Glacial geology; Ice sheets; Interpretation; Invertebrata; Isotope ratios; Isotopes; Microfossils; Middle Miocene; Miocene; Neogene; O-18/O-16; Ocean circulation; Oxygen; Paleo-oceanography; Paleoclimatology; Patterns; Protista; Stable isotopes; Tertiary
Record ID: 1994037752
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands

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