Evidence for enhanced convection of North Pacific Intermediate Water to the low-latitude Pacific under glacial conditions

• Published in: Paleoceanography
• Main Authors: Max, L., Rippert, N., Lembke-jene, L., Mackensen, A., Nürnberg, D., Tiedemann, R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Geophysical Union 2017
• Subjects: Bering Sea; Pacific; Planktonic foraminifera; Subarctic
• Online Access: https://archimer.ifremer.fr/doc/00420/53196/54997.pdf; https://archimer.ifremer.fr/doc/00420/53196/54998.xls; https://archimer.ifremer.fr/doc/00420/53196/54999.xls; https://doi.org/10.1002/2016PA002994; https://archimer.ifremer.fr/doc/00420/53196/

We provide high-resolution foraminiferal stable carbon isotope (delta C-13) records from the subarctic Pacific and Eastern Equatorial Pacific (EEP) to investigate circulation dynamics between the extratropical and tropical North Pacific during the past 60 kyr. We measured the delta C-13 composition of the epibenthic foraminiferal species Cibicides lobatulus from a shallow sediment core recovered from the western Bering Sea (SO201-2-101KL; 58 degrees 52.52' N, 170 degrees 41.45' E; 630 m water depth) to reconstruct past ventilation changes close to the source region of Glacial North Pacific Intermediate Water (GNPIW). Information regarding glacial changes in the delta C-13 of subthermocline water masses in the EEP is derived from the deep-dwelling planktonic foraminifera Globorotaloides hexagonus at ODP Site 1240 (00 degrees 01.31' N, 82 degrees 27.76' W; 2921m water depth). Apparent similarities in the long-term evolution of delta C-13 between GNPIW, intermediate waters in the eastern tropical North Pacific and subthermocline water masses in the EEP suggest the expansion of relatively delta C-13-depleted, nutrient-enriched, and northern sourced intermediate waters to the equatorial Pacific under glacial conditions. Further, it appears that additional influence of GNPIW to the tropical Pacific is consistent with changes in nutrient distribution and biological productivity in surface waters of the glacial EEP. Our findings highlight potential links between North Pacific mid-depth circulation changes, nutrient cycling, and biological productivity in the equatorial Pacific under glacial boundary conditions.