Orbital scale variations and timescales from the Arctic Ocean

Abstract

We investigate geochemical measurements from the Arctic Coring Expedition to derive sedimentation rates for selected intervals in the early and middle Eocene. This analysis is performed by quantifying cyclical variations in physical property data and elemental concentrations derived with an X-ray fluorescence (XRF) core scanner. Our results show that physical properties and XRF-derived elemental concentrations are coherent and correlated to each other. Changes in elemental concentrations occur on depth scales from decimeters to meters and correspond to varying contributions of detrital minerals and biogenic silica. We confirm and refine sedimentation rates of the order of 10 to 25 m Ma-1. These rates were obtained independently through biostratigraphic and magnetostratigraphic methods. We observe a strong imprint of astronomically sourced cycles, particularly through climatic precession. This observation allows us to test recently proposed theoretical calculations of insolation. Copyright 2008 by the American Geophysical Union.