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Anomalous Pacific‐Antarctic Ridge volcanism precedes glacial Termination 2

Lund, David C. and Seeley, Emily I. and Asimow, Paul D. and Lewis, Madeline and McCart, Sarah and Mudahy, Anna (2018) Anomalous Pacific‐Antarctic Ridge volcanism precedes glacial Termination 2. Geochemistry, Geophysics, Geosystems, 19 (8). pp. 2478-2491. ISSN 1525-2027. doi:10.1029/2017GC007341.

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We present results from a well‐dated sediment core on the Pacific‐Antarctic Ridge (PAR) that document a ∼15 cm thick layer of basaltic ash shards that precedes the penultimate deglaciation (Termination 2). The glasses have MORB composition consistent with an axial source and their morphologies are typical of pyroclastic deposits created by submarine volcanism. The ash layer was deposited ∼7 km from the PAR axis, a distance that implies buoyant plumes lofted debris high into the water column with subsequent fallout to the core location. We infer plume rise height using grain settling velocities, the water depth at the core site, and deep ocean current speeds from ARGO floats. Rise heights of 1.5 km or less require unrealistically large current speeds to transport grains to the core site. Instead, the data are consistent with a plume rise height of at least 2 km, implying that T2 was an interval of anomalous volcanism along this segment of the PAR. The timing and duration of the ash deposit is consistent with glacial‐interglacial modulation of ridge magmatism. Volcaniclastic records from additional locations will be necessary to assess whether the PAR record is a rare find or it is representative of mid‐ocean ridge volcanism during glacial terminations.

Item Type:Article
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Lund, David C.0000-0002-4847-2889
Asimow, Paul D.0000-0001-6025-8925
Additional Information:© 2018 American Geophysical Union. Received 14 NOV 2017; Accepted 18 APR 2018; Accepted article online 7 MAY 2018; Published online 16 AUG 2018. DCL and EIS were supported by NSF award OCE‐1558641 and the University of Connecticut. We are grateful to David Cady at UCONN for assistance with ICP‐MS analyses and Lora Wingate at the University of Michigan and Jean Lynch‐Stieglitz at Georgia Tech for assistance with stable isotope analyses. We are also indebted to the Oregon State University Core Repository for the curation of core OC170‐26‐159. The OSU Repository is supported by NSF award OCE‐1558679. MJL and PDA were supported by NSF awards OCE‐1558372 and EAR‐1551433. Thanks to Nathan Dalleska at Caltech for assistance with LA‐ICP‐MS analyses and to George Rossman for use of the FTIR lab. Electron probe work was carried out in the Caltech GPS Division analytical facility, which is supported in part by NSF Grants EAR‐0318518 and DMR‐0080065. Data presented in the manuscript will be available on the NOAA NGDC Paleoclimate Database and through IEDA PetDB.
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University of ConnecticutUNSPECIFIED
Subject Keywords:volcanism; glacial; interglacial; Pacific Antarctic Ridge; Termination 2
Issue or Number:8
Record Number:CaltechAUTHORS:20180507-102834094
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Official Citation:Lund, D. C., Seeley, E. I., Asimow, P. D., Lewis, M. J., McCart, S. E., & Mudahy, A. A. (2018). Anomalous Pacific‐Antarctic ridge volcanism precedes Glacial Termination 2. Geochemistry, Geophysics, Geosystems, 19, 2478–2491.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86243
Deposited By: Tony Diaz
Deposited On:07 May 2018 18:04
Last Modified:15 Nov 2021 20:36

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