Modeling Cenozoic sedimentation in the central equatorial Pacific and implications for true polar wander

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    Abstract

    High productivity along the central Pacific equator has left thick deposits of calcareous and siliceous ooze. West of 102°W, these have deposited on the Pacific plate which has been drifting northwards and therefore the thickest deposits are displaced north of the equator. This study attempts to simulate the sediment distribution using information from Deep Sea Drilling Project (DSDP) cores and models for Pacific plate motion. The DSDP core data are used to account for accumulation rate variations with time, paleolatitude and paleodepth, accounting for variable carbonate dissolution. The model predicts the distribution on 35-50 Ma seafloor relatively well and demonstrates that the sedimentary bulge is distorted by variable dissolution over a regional bathymetry gradient due to the northern edge of the South Pacific Superswell. A westerly deepening of the carbonate compensation depth and sedimentary lysocline evolution are proposed, which improve the model for seafloor 30 Ma and older. The degree of match between model and data provides a test of the amount of northward drift of the Pacific plate and, assuming a model for Pacific hotspots motion, of true polar wander (TPW, motion of the hotspot frame relative to the Earth's spin axis). Assuming the Duncan and Clague [1985] model for Pacific hotspots motion, the sedimentary modeling favors TPW models which have little or no effect on the central Pacific paleoequator over the past 30 Ma. We also explore implications of interhotspot motion and the suggestion that the bend in the Hawaiian volcanic chain represents an abrupt change in Pacific hotspot motion within the last 5 Ma.
    Original languageEnglish
    Pages (from-to)17749-17766
    Number of pages17
    JournalJournal of Geophysical Research
    Volume103
    Issue number8
    DOIs
    Publication statusPublished - 10 Aug 1998

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