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Does sea level influence mid-ocean ridge magmatism on Milankovitch timescales?

Lund, David C. and Asimow, Paul D. (2011) Does sea level influence mid-ocean ridge magmatism on Milankovitch timescales? Geochemistry Geophysics Geosystems, 12 . Art. No. Q12009. ISSN 1525‐2027.

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Magma production at mid-ocean ridges is driven by seafloor spreading and decompression melting of the upper mantle. In the special case of Iceland, mantle melting may have been amplified by ice sheet retreat during the last deglaciation, yielding anomalously high rates of subaerial volcanism. For the remainder of the global mid-ocean ridge system, the ocean may play an analogous role, with lowering of sea level during glacial maxima producing greater magma flux to ridge crests. Here we show that the mantle decompression rate associated with changes in sea level is a substantial fraction of that from plate spreading. Modeled peaks in magma flux occur after sea level drops rapidly, including the Marine Isotope Stage (MIS) 5/4 and 3/2 transitions. The minimum in simulated flux occurs during the mid-Holocene, due to the rapid sea level rise at the MIS 2/1 boundary. The model results are highly sensitive to melt migration rate; rates of ~1 m/yr produce small signals, while those >5 m/yr yield substantial anomalies. In the latter case, sea level-driven magma flux varies by 15–100% relative to the long-term average, with the largest effect occurring at slow-spreading ridges. We suggest that sedimentary time series of hydrothermal particle flux, oceanic Os isotopic ratio, and oceanic radiocarbon may serve as proxies for magma-flux variations at mid-ocean ridges. Although well-dated records are rare, preliminary data from the Pacific and Atlantic suggest hydrothermal metal flux was elevated during MIS 2 and 4, broadly consistent with our modeling results.

Item Type:Article
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Lund, David C.0000-0002-4847-2889
Asimow, Paul D.0000-0001-6025-8925
Additional Information:© 2011 by the American Geophysical Union. Received 10 May 2011; Revised 12 October 2011; Accepted 13 October 2011; Published 13 December 2011. We thank John Maclennan, Donna Blackman, and three anonymous reviewers for their constructive criticism. We would also like to thank Peter Huybers, Marc Spiegelman, and John Southon for comments and suggestions. Funding for this project was in part provided by the University of Michigan (D. Lund).
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University of MichiganUNSPECIFIED
Subject Keywords:Milankovitch; magmatism; sea level
Record Number:CaltechAUTHORS:20120123-123856074
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Official Citation:Lund, D. C., and P. D. Asimow (2011), Does sea level influence mid-ocean ridge magmatism on Milankovitch timescales?, Geochem. Geophys. Geosyst., 12, Q12009, doi:10.1029/2011GC003693
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28920
Deposited By: Tony Diaz
Deposited On:27 Jan 2012 22:46
Last Modified:09 Mar 2020 13:19

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