Effects of productivity, glaciation, and ventilation on late Quaternary sedimentary redox and trace element accumulation on the Vancouver Island margin, western Canada

• Published in: Paleoceanography
• Main Authors: Chang, Alice S., Pedersen, Thomas F., Hendy, Ingrid L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Scandinavian University Press 2014
• Subjects: Northeast Pacific Ocean; Sedimentary Redox; Trace Elements; Productivity; Cordilleran Glaciation; Atmospheric and Oceanic Sciences; Science; Canada; Greenland; Pacific; Greenland ice core; ice core; Ice Sheet; North Atlantic
• Online Access: https://hdl.handle.net/2027.42/108369; https://doi.org/10.1002/2013PA002581

Variations in chalcophile and redox‐sensitive trace elements are examined at high‐resolution intervals from a ~50 kyr long sediment core (MD02‐2496) from the Vancouver Island margin. Enrichments of Ag, Cd, Re, U, and Mo above lithogenous levels, signifying sedimentary suboxia and anoxia, occurred during the early Holocene and Bølling/Allerød, and during warm interstadial events of Marine Isotope Stage (MIS) 3. Down‐core trace element profiles co‐vary with productivity proxy records (opal, CaCO 3 , and marine organic carbon), and with sedimentary nitrogen isotope ratios, which reflect variably enriched nitrate upwelled from intermediate waters that were transported northward from the Eastern Tropical North Pacific. The similarity of the MD02‐2496 record with records from the southern portion of the California Current System (CCS), and to the Greenland ice core oxygen isotope record during warm climate intervals, suggests that sedimentary redox conditions along the California Current responded to local productivity, to North Atlantic climate change and to tropical Pacific surface water processes via long‐distance teleconnections. Concentrations of trace elements and productivity proxies were relatively depleted during the Younger Dryas, cool stadial events of MIS 3, and in two episodes of glaciomarine sedimentation from ~14.7 to 30.5 kyr BP (last glacial maximum, LGM), and from 44 to 50.4 kyr BP. Cordilleran Ice Sheet advancement onto the Vancouver Island continental shelf during the LGM led to intervals of increased terrigenous sedimentation and greatly reduced productivity not seen in the southern portion of the CCS, and along with ventilation of North Pacific Intermediate Waters, resulted in brief sedimentary oxic conditions. Key Points Trace elements co‐vary with marine productivity proxies during warm climates Productivity controls pore water oxygen and sedimentary redox conditions Cordilleran ice sheet directly affected productivity and sedimentary redox Peer Reviewed ...