The Meiji Drift, NW Pacific

A large sediment deposit known as the Meiji Drift lies just outside of the Bering Sea in the northwestern Pacific Ocean. It is thought that the deposit is related to deep-water circulation in (and out of) the Bering Sea (Dave Scholl et al.), although no notable deep water forms there presently. We have applied bulk sediment 40Ar-39Ar dating and Nd isotopic analyses to the silt-sized fraction from Ocean Drilling Project core site 884 (51°27' N, 168°20' E). Measurements are made over the last 130,000 years to document sediment source(s) to the Meiji Drift and to determine whether provenance changes through time.

Some Results

There is an order-of-magnitude range in bulk sediment 40Ar-39Ar ages and around ten εNd units of change, both varying on glacial-interglacial cycles. During glacials, bulk sediment 40Ar-39Ar plateau ages range between 40-80 Ma while Nd isotopic values range from εNd = -1 to εNd = +2. During interglacials, the downcore samples become considerably younger and more radiogenic, with bulk sediment plateau ages falling between 2-15 Ma and Nd isotopic values ranging between εNd = +5 to εNd = +9. The Ar-Nd data illustrate that the Kamchatkan and Aleutian Volcanic Arcs straddling the Meiji Drift contribute the majority of sediment during interglacials. Conversely, older source rocks such as those drained by the Yukon River are the dominant origin of sediments during glacials.