Sediments of the Lomonosov Ridge and Makarov Basin: A Pleistocene stratigraphy for the North Pole

Abstract

Sediments of 16 short cores taken as part of the Lomonosov Ridge Experiment (LOREX) can be organized into the first Pleistocene stratigraphy for the North Polar region. This stratigraphy can be correlated with stratigraphic units described from the Alpha-Chukchi areas, ∼300 km distant. The LOREX cores include at least 12 sedimentary subunits differentiated by texture, color, and carbonate content. The units are silty and arenaceous lutites and are principally glacial-marine. Benthic and planktonic foraminifera, degree of bioturbation, and Fe-Mn micro-nodule abundance generally are positively correlated. Foraminifera in core B-8, from 3,956 m in the Makarov Basin, may have been affected by CCD fluctuations that did not affect fossils in core B-24, from 1,600 m on the crest of the Lomonosov Ridge. The 12 stratigraphic units were deposited during the late Pleistocene and represent the same major sedimentary events as those of stratigraphic units K, L, and M of the Amerasian Basin. This correlation is excellent evidence for the remarkable and widespread uniform depositional style of glacial-marine sediment. Times of major glacial ice transport reflect deglaciation events in the central Arctic Ocean. Surface currents during deglaciation transport glacial ice in a more or less uniform pattern over at least 50% of the Arctic Ocean. Even thin sedimentary units deposited during relatively long time intervals are correlated over >500,000 km 2 .