DO MARINE SEDIMENTS FROM THE CASCADIA MARGIN RECORD THE GEOMAGNETIC FIELD? A STUDY OF PISTON CORES COLLECTED DURING OC2006A FROM THE UPPER SLOPE ADJACENT TO GRAYS HARBOR CANYON, WA

Magnetic minerals within marine sediments can record paleomagnetic secular variation, or past changes in Earth’s self-generating magnetic field. On the Cascadia Margin, prior work has shown that high levels of marine productivity led to magnetic mineral diagenesis that is thought to obscure and potentially obliterate the paleomagnetic record, thus limiting paleomagnetic and environmental magnetic studies in this region. However, careful evaluation of prior studies and new work as part of the Cascadia H.O.P.S. program suggests PSV signals may still be preserved in the specific depositional environment on the margin, including sites adjacent to Grays Harbor Canyon. We present the first paleomagnetic results from the upper continental slope of Sites OC2006A 16JC and 18JC (including accompanying trigger cores), which will be evaluated against established paleomagnetic criteria to discern the context of the sediment and sedimentation processes associated with that record. The sediments’ physical and magnetic properties are used to evaluate the paleomagnetic record, using shipboard multi-sensor track data, CT scan, and XRF data along with alternating field demagnetization from natural remanent magnetization, anhysteretic remanent magnetization, and magnetic susceptibility from u-channels. Common paleomagnetic features observed in coeval intervals of Sites 16JC and 18JC are considered likely to be geomagnetic in origin, which will be compared to established paleomagnetic secular variation records from regional stacks (NEPSIAS), lakes (Fish Lake, OR), and volcanic data to explore and evaluate the magnetostratigraphic potential of Cascadia Margin sediments.