High productivity along the central Pacific equator has left thick
deposits of calcareous and siliceous ooze. West of 102 deg 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.
Mitchell, N. C., Modeling Cenozoic sedimentation in the central equatorial Pacific and
implications for true polar wander,
J. Geophys. Res., 103, 17749-17766, 1998.