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Provenance of plumes in global convection models

Hassan, Rakib and Flament, Nicolas and Gurnis, Michael and Bower, Dan J. and Müller, Dietmar (2015) Provenance of plumes in global convection models. Geochemistry, Geophysics, Geosystems, 16 (5). pp. 1465-1489. ISSN 1525-2027. http://resolver.caltech.edu/CaltechAUTHORS:20150710-133556115

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Abstract

In global convection models constrained by plume motions and subduction history over the last 230 Myr, plumes emerge preferentially from the edges of thermochemical structures that resemble present-day large low shear velocity provinces (LLSVPs) beneath Africa and the Pacific Ocean. It has been argued that large igneous provinces (LIPs) erupting since 200 Ma may originate from plumes that emerged from the edges of the LLSVPs and numerical models have been devised to validate this hypothesis. Although qualitative assessments that are broadly in agreement with this hypothesis have been derived from numerical models, a quantitative assessment has been lacking. We present a novel plume detection scheme and derive Monte Carlo-based statistical correlations of model plume eruption sites and reconstructed LIP eruption sites. We show that models with a chemically anomalous lower mantle are highly correlated to reconstructed LIP eruption sites, whereas the confidence level obtained for a model with purely thermal plumes falls just short of 95%. A network of embayments separated by steep ridges form in the deep lower mantle in models with a chemically anomalous lower mantle. Plumes become anchored to the peaks of the chemical ridges and the network of ridges acts as a floating anchor, adjusting to slab push forces through time. The network of ridges imposes a characteristic separation between conduits that can extend into the interior of the thermochemical structures. This may explain the observed clustering of reconstructed LIP eruption sites that mostly but not exclusively occur around the present-day LLSVPs.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1002/2015GC005751DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2015GC005751/abstractPublisherArticle
Additional Information:© 2015 American Geophysical Union. Received 27 January 2015; Accepted 17 April 2015; Accepted article online 24 April 2015; Published online 26 May 2015. We obtained CitcomS (version 3.2) from the Computational Infrastructure for Geodynamics (http://geodynamics.org/). GPlates (http://www.gplates.org/) is developed at the University of Sydney, the California Institute of Technology, and the Geological Survey of Norway. All figures in this paper have been made with Matplotlib [Hunter, 2007], except Figure 8b, made using ParaView [Squillacote and Ahrens, 2007]. We thank Rhodri Davies and Allen McNamara for comprehensive and insightful reviews. R.H. and N.F. were supported by Statoil ASA. D.M., N.F., and R.H. were also supported by ARC grant IH130200012. M.G. and D.J.B. were partially supported by Statoil ASA and the NSF (through EAR-1161046 and EAR-1247022). This research was undertaken with the assistance of resources from the National Computational Infrastructure (NCI), which is supported by the Australian Government.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Statoil ASAUNSPECIFIED
Australian Research Council (ARC)IH130200012
NSFEAR-1161046
NSFEAR-1247022
Subject Keywords:mantle plumes; LLSVP; core-mantle boundary; thermochemical convection; statistical correlation
Record Number:CaltechAUTHORS:20150710-133556115
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150710-133556115
Official Citation:Hassan, R., N. Flament, M. Gurnis, D. J. Bower, and D. Müller (2015), Provenance of plumes in global convection models, Geochem. Geophys. Geosyst., 16, 1465–1489, doi:10.1002/2015GC005751.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58850
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:10 Jul 2015 22:52
Last Modified:02 Nov 2015 19:48

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