Southern Hemisphere Miocene bottom-water circulation; a palaeobathymetric analysis

Author(s): Sykes, T. J. S.; Ramsay, A. T. S.; Kidd, Robert Benjamin
Author Affiliation(s): Primary:
University of Wales, Department of Earth Sciences, Cardiff, United Kingdom
Other:
University of London, United Kingdom
Volume Title: Geological evolution of ocean basins; results from the Ocean Drilling Program
Volume Author(s): Cramp, A., editor; MacLeod, C. J.; Lee, S. V.; Jones, E. J. W.
Source: Geological evolution of ocean basins; results from the Ocean Drilling Program, edited by A. Cramp, C. J. MacLeod, S. V. Lee and E. J. W. Jones. Geological Society Special Publications, Vol.131, p.43-54. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0305-8719. ISBN: 1-86239-003-7
Note: In English. 45 refs.; illus., incl. sketch maps
Summary: Palaeobathymetric reconstructions of the southern hemisphere are used to assess the potential flow paths and extent of proto-Antarctic Bottom Water (proto-AABW) for three time slices during the Miocene: 20 Ma (early), 15 Ma (middle) and 10 Ma (late). The depth ranges of fluctuations in this water mass were derived from its waxing/waning curve, based on an analysis of hiatuses within drill sites from the Indian Ocean. Proto-AABW was likely to be expressed at depths below -4400 m, -5500 m and -4700 m at 20 Ma and 10 Ma respectively. These depth ranges were extended into the South Atlantic and South Pacific Oceans to allow a first approximation of potential proto-AABW flow paths. An understanding of modern oceanography and the distribution of suspended sediment particle concentrations within the nepheloid layer and sediment drifts were used to constrain flow paths. This interpretation was made on the basis that proto-Antarctic Bottom Water was an analogue of its modern equivalent and was likely to have followed similar flow paths. The palaeobathymetric analysis reveals that at 20 Ma (early Miocene) the deep basins of the southern hemisphere were well connected and proto-AABW flow paths were likely to have been widespread. By 15 Ma (middle Miocene), however, the waning of proto - AABW led to the disconnection of the deep ocean basins and this water mass was probably restricted to the Antarctic Basin. Waxing of proto-AABW during the late Miocene allowed the reconnection of the deep basins but not to the same extent as at 20 Ma (early Miocene).
Year of Publication: 1998
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Antarctic Bottom Water; Antarctic Ocean; Atlantic Ocean; Cenozoic; Miocene; Modern analogs; Neogene; Ocean Drilling Program; Ocean circulation; Pacific Ocean; Paleo-oceanography; Paleobathymetry; Particles; Reconstruction; Ross Sea; South Atlantic; South Pacific; Southern Hemisphere; Southern Ocean; Suspended materials; Tertiary; Unconformities; Weddell Sea
Record ID: 1998075056
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute.

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