CENOZOIC SEDIMENTATION HISTORY OF THE CENTRAL NORTH PACIFIC - INFERENCES FROM THE ELEMENTAL GEOCHEMISTRY OF CORE LL44-GPC3

The concentrations of thirty-nine elements in 324 samples show large v ariations in sediments down the 24.3 m length of LL44-GPC3, a piston c ore of pelagic clay from the central North Pacific (30-degrees 19'N, 1 57-degrees 49.9'W) that contains a relatively continuous record of sed imentation since the late Cretaceous. Strong interelement correlations identify five groups of elements whose variance is related and which we interpret to represent porewater salts, silicates, biogenic phospha tes, and hydrothermal and hydrogenous oxyhydroxide precipitates. Inter element ratios, when combined with mineralogical, sedimentological, an d site-backtrack data, indicate that at least five distinct sources co ntributed to the aluminosilicate fraction of the sediments in the core . Eight endmember sediment source components (two eolian, two volcanic , two biogenous, one hydrothermal, and one hydrogenous) are modeled an d quantified by total inversion. Accumulation rates of these component s and of thirty-nine elements vary dramatically for stratigraphically defined intervals within the Cenozoic. Continuous accumulation-rate pr ofiles based on a model combining stratigraphic data and an assumed co nstant flux of hydrogenous Co yield a general sedimentation model that reflects variations in the sedimentary environment as the LL44-GPC3 s ite migrated from near the equator in the late Cretaceous to its prese nt location north of Hawaii.