Southern Hemisphere palaeobathymetry

Author(s): Sykes, T. J. S.; Royer, J. Y.; 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
Laboratoire de Geodynamique sous Marine, France
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.3-42. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0305-8719. ISBN: 1-86239-003-7
Note: In English. 86 refs.; illus., incl. 1 table, sketch maps
Summary: Digital grids, with a spatial resolution of .5°, were compiled using bathymetry, sediment thickness, and oceanic crustal ages for the southern hemisphere to calculate sediment-free palaeobathymetric charts for late Cretaceous (110 Ma) to the present. These reconstructions allow the definition and quantification of the bathymetric evolution of the seaways and gateways within this region. Pre-60 Ma the palaeobathymetry and the interconnection of the deeper ocean basin was dominated by the formation of hotspot-related ridges and plateaux. Between 40 Ma and the present the palaeobathymetry is characterized by the opening of numerous gateways as the Tasman Rise separated from Antarctica, the Mascarene Plateau split from the Chagos-Laccadive Ridge, Broken Ridge rifted from the northern Kerguelen Plateau, the Crozet Plateau separated from the Madagascar Ridge, and the Scotia Sea opened. The validity of thse palaeobathymetric reconstructions is demonstrated by comparing the digital gridded data sets, from which they were calculated, with data derived from 39 Deep Sea Drilling Project and Ocean Drilling Program drill sites. Comparison of drill site data with the gridded data revealed positive correlations between crustal ages and bathymetry, whereas the sediment thickness data showed no correlation. The lack of any correlation for the sediment thickness data, however, did not preclude a positive correlation between sediment-free bathymetries. The difference between expected 'true' palaeobathymetry, that is with sediments older than the time of reconstruction decompacted and reloaded back onto oceanic crust, and the sediment-free palaeobathymetry was shown to be less than 600 m for 87.5% of the data. The greatest differences occur where sediment thicknesses are greatest, i.e. within the deep ocean basins which are in close proximity to the continental margin.
Year of Publication: 1998
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Antarctica; Bathymetry; Broken Ridge; Cenozoic; Chagos-Laccadive Plateau; Cretaceous; Crozet Plateau; Crust; Deep Sea Drilling Project; Digital data; Gondwana; Hot spots; Kerguelen Plateau; Madagascar Ridge; Mascarene Plateau; Mesozoic; Ocean Drilling Program; Ocean floors; Oceanic crust; Paleobathymetry; Paleolatitude; Paleomagnetism; Plate tectonics; Reconstruction; Scotia Sea; Southern Hemisphere; Tasman Rise; Thickness
Record ID: 1998075055
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute.

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