Manganese and color cycles in Arctic Ocean sediments constrain Pleistocenechronology

Sequential variations in manganese (Mn) content and color of deepsea sedime nts retrieved from the Lomonosov Ridge (87 degrees N) in the central Arctic Ocean apparently mimic low-latitude delta(18)O glacial-interglacial cyclic ity, thereby providing stratigraphic information that together with biostra tigraphic data permit the construction of a detailed chronological model. C orrelation of this Mn and color chronology to established apparent Brunhes- age estimates of geomagnetic excursions reveals a remarkable fit between th ese two independently derived time scales. The Mn and color cycles probably provide paleoenvironmental information about material fluxes in the Arctic Ocean over the past 1 m.y. We suggest that the primary source for the obse rved manganese variations in our sediment core is northern Siberia, which h as extensive peat bogs and boreal forests. These Siberian source areas coul d operate in an off and on mode tuned to Pleistocene glacial and interglaci al periods. Contrasts in ventilation of Arctic Ocean waters during intergla cial-glacial cycles probably could also enhance the observed Mn and color v ariability.