Late Cenozoic sedimentation and metal deposition in the North Pacific |
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| Authors: | David Kadko |
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| Institution: | College of Oceanography, Oregon State University, Corvallis, Oregon 97331, U.S.A. |
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| Abstract: | Similar major chemical variations in cores from three sites across a wide area of the North Pacific are modeled by coupling the vertical and horizontal motions of the Pacific plate with a constant authigenic flux of elements into the sediments. Superimposed over this flux is an input of detrital material of relatively constant chemical composition. The major features of sediment chemistry of cores from the North Pacific apparently vary in a fairly uniform and systematic manner, and these variations are consistent with Cenozoic plate movement. Elements with a significant authigenic component (e.g., Mn, Co, Cu, Ni) display high concentrations at depth in cores that correspond to the period when the seafloor, while under the low-productivity, subtropical gyre of the N. Pacific, accumulated sediment at an extremely slow rate (~1 mm/kyr). These concentrations were diluted when the sites experienced an increase in the eolian mass accumulation rate first brought about by migration into the influence of the westerlies and then, dominantly, by the huge input of wind-blown detritus which corresponded to the onset of Northern Hemisphere glaciation. A comparison of 10Be profiles to the profiles of metal concentrations is used to reveal the occurrence of haituses in the sediment column over the past 8 m.y. |
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