Paleoclimate, paleoventilation, and paleomagnetism as recorded in a 17kyr marine sediment record from the SE Alaska margin

• Main Author: Davies, Maureen Helen
• Other Authors: Mix, Alan C., Stoner, Joseph S., Brook, Edward, Pisias, Nicklas G., Schmittner, Andreas, Lancaster, Stephen, College of Oceanic and Atmospheric Sciences, Oregon State University. Graduate School
• Format: Doctoral or Postdoctoral Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Bering Strait; Foraminifera*; Greenland; Greenland ice core; ice core; NGRIP; Alaska; Beringia
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/tx31qm374

The deglacial behavior of the sub-Arctic North Pacific is poorly constrained, with many published records suffering from limited age control due to extensive post- depositional biogenic carbonate dissolution. Potential alternative dating methods could include the correlation of stable-isotopic and/or paleomagnetic secular variation records to an independently-dated regional template, however no such template currently exists. Cores EW0408-85JC (59°33.32'N, 144°9.21'W, 682 m water depth) and EW0408-79JC (59°33.32'N, 144°9.21'W, 682 m water depth) are located above the carbonate compensation depth on the Gulf of Alaska margin, affording an opportunity to inter- compare stable-isotopic and paleomagnetic variability from a single location, as well as to place observations of Northeast Pacific paleoclimate and paleomagnetic secular variation in a global context via an independent radiocarbon-based chronology. We evaluate three possible age models for core EW0408-85JC and their implications for North Pacific stable isotopic and paleoventilation behavior. These include calibrated planktonic and benthic foraminiferal radiocarbon dates, assuming constant reservoir ages, as well as a correlation of planktonic δ¹⁸O in foraminifera to δ¹⁸O in a layer-counted Greenland ice core (NGRIP). We conclude that the calibrated planktonic dates provide the most accurate chronology. Benthic foraminiferal radiocarbon dates evaluated on this age model indicate that intermediate-depth ventilation ages at the site increased to >2,670 ± 180 during Termination 1, implying reduced ventilation relative to the Holocene average of 1,740 ± 210 yr. The shift to lower ventilation ages occurs at ~10,500 cal ybp, coeval with the flooding of Beringia and the opening of the Bering Strait, suggesting that flooded shelves and net export of low- salinity surface waters enhanced ventilation of the North Pacific. Oxygen isotope data from planktonic and benthic foraminifera, interpreted on this age model, document surface freshening by 16,650 ± 170 cal ...