TY - JOUR
T1 - Northwest Pacific ice-rafted debris at 38 degrees N reveals episodic ice-sheet change in late Quaternary Northeast Siberia
AU - McCarron, A.P.
AU - Bigg, G.R.
AU - Brooks, H.
AU - Leng, M.J.
AU - Marshall, J.D.
AU - Ponomareva, V.
AU - Portnyagin, M.
AU - Reimer, P.J.
AU - Rogerson, M.
N1 - Funding information: This work was largely funded by a studentship for APM from the Natural Environment Research Council Adapting to the Challenges of a Changing Environment (NERC-ACCE) Doctoral Training Partnership (NE/L002450/1). The stable isotope analysis was funded by a NERC Isotope Geoscience Facilities Steering Committee (NIGFSC) award. Our foraminifera counts were funded by the Sheffield Undergraduate Research Experience (SURE) Scheme. Samples were provided by the Integrated Ocean Drilling Program (IODP). We thank L. Ma at the Sorby Centre for Electron Microscopy at the University of Sheffield for support with SEM imaging and EDS analysis. We also thank R. Ashurst, A. Smalley, D. Finlayson and J. Hufton at the Physical Geography Laboratory, Department of Geography, University of Sheffield for providing resources and technical support. Research by MP and VP including acquisition of geochemical data and work on the paper was supported by the Russian Science Foundation grant #16-17-10035. We thank the reviewer for encouraging us to re-structure parts of this manuscript, which made for a more coherent argument.
PY - 2020/11/18
Y1 - 2020/11/18
N2 - The ice-rafted-debris (IRD) record of the open Northwest Pacific points towards the existence of substantial glacial ice on the Northeast Siberian coast during the late Quaternary. However, the scale and timing of glaciation and de-glaciation remains controversial due to the dearth of both onshore and offshore records. Existing IRD data suggests at least one event of dynamic and abrupt change during mid-late Marine Isotope Stage (MIS 3) which mimics the massive collapse of the Laurentide ice sheet during Heinrich Events. It is uncertain whether other events of this magnitude occurred during the late Quaternary. Here we present a ∼160,000 yr IRD series, planktic foraminiferal counts and an age model, derived from a benthic δ18O curve, radiocarbon dates and tephrochronology, from core ODP 1207A (37.79°N, 162.75°E), revealing the presence of low but episodic flux of IRD. We conclude that glacial Northwest Pacific icebergs spread further south than previously thought, with icebergs emanating from Northeast Siberia being transported to the transition region between the subpolar and subtropical waters, south of the subarctic front during at least the Quaternary's last two glacial periods. The episodic nature of the 1207A IRD record during the last glacial, combined with coupled climate-iceberg modelling, suggests occasional times of much enhanced ice flux from the Kamchatka-Koryak coast, with other potential sources on the Sea of Okhotsk coast. These findings support the hypothesis of a variable but extensive ice mass during the last glacial over Northeast Siberia, particularly early in the last glacial period, behaving independently of North American and Eurasian ice masses. In strong contrast, IRD was absent during much of the penultimate glacial Marine Isotope Stage (MIS) 6 suggesting the possibility of very different Northeast Siberian ice coverage between the last two glacial periods.
AB - The ice-rafted-debris (IRD) record of the open Northwest Pacific points towards the existence of substantial glacial ice on the Northeast Siberian coast during the late Quaternary. However, the scale and timing of glaciation and de-glaciation remains controversial due to the dearth of both onshore and offshore records. Existing IRD data suggests at least one event of dynamic and abrupt change during mid-late Marine Isotope Stage (MIS 3) which mimics the massive collapse of the Laurentide ice sheet during Heinrich Events. It is uncertain whether other events of this magnitude occurred during the late Quaternary. Here we present a ∼160,000 yr IRD series, planktic foraminiferal counts and an age model, derived from a benthic δ18O curve, radiocarbon dates and tephrochronology, from core ODP 1207A (37.79°N, 162.75°E), revealing the presence of low but episodic flux of IRD. We conclude that glacial Northwest Pacific icebergs spread further south than previously thought, with icebergs emanating from Northeast Siberia being transported to the transition region between the subpolar and subtropical waters, south of the subarctic front during at least the Quaternary's last two glacial periods. The episodic nature of the 1207A IRD record during the last glacial, combined with coupled climate-iceberg modelling, suggests occasional times of much enhanced ice flux from the Kamchatka-Koryak coast, with other potential sources on the Sea of Okhotsk coast. These findings support the hypothesis of a variable but extensive ice mass during the last glacial over Northeast Siberia, particularly early in the last glacial period, behaving independently of North American and Eurasian ice masses. In strong contrast, IRD was absent during much of the penultimate glacial Marine Isotope Stage (MIS) 6 suggesting the possibility of very different Northeast Siberian ice coverage between the last two glacial periods.
KW - Northwest Pacific
KW - ODP site 1207A
KW - ice-rafted debris
KW - ice-sheet
UR - http://www.scopus.com/inward/record.url?scp=85096394337&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2020.116650
DO - 10.1016/j.epsl.2020.116650
M3 - Article
SN - 0012-821X
VL - 553
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
M1 - 116650
ER -