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Geochemical portray of the Pacific Ridge: New isotopic data and statistical techniques

Hamelin, Cédric and Dosso, Laure and Hanan, Barry B. and Moreira, Manuel and Kositsky, Andrew P. and Thomas, Marion Y. (2011) Geochemical portray of the Pacific Ridge: New isotopic data and statistical techniques. Earth and Planetary Science Letters, 302 (1-2). pp. 154-162. ISSN 0012-821X. https://resolver.caltech.edu/CaltechAUTHORS:20110317-130410278

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Abstract

Samples collected during the PACANTARCTIC 2 cruise fill a sampling gap from 53° to 41° S along the Pacific Antarctic Ridge (PAR). Analysis of Sr, Nd, Pb, Hf, and He isotope compositions of these new samples is shown together with published data from 66°S to 53°S and from the EPR. The recent advance in analytical mass spectrometry techniques generates a spectacular increase in the number ofmultidimensional isotopic data for oceanic basalts. Working with such multidimensional datasets generates a new approach for the data interpretation, preferably based on statistical analysis techniques. Principal Component Analysis (PCA) is a powerful mathematical tool to study this type of datasets. The purpose of PCA is to reduce the number of dimensions by keeping only those characteristics that contribute most to its variance. Using this technique, it becomes possible to have a statistical picture of the geochemical variations along the entire Pacific Ridge from 70°S to 10°S. The incomplete sampling of the ridge led previously to the identification of a large-scale division of the south Pacific mantle at the latitude of Easter Island. The PCA method applied here to the completed dataset reveals a different geochemical profile. Along the Pacific Ridge, a large-scale bell-shaped variation with an extremum at about 38°S of latitude is interpreted as a progressive change in the geochemical characteristics of the depleted matrix of the mantle. This Pacific Isotopic Bump (PIB) is also noticeable in the He isotopic ratio along-axis variation. The linear correlation observed between He and heavy radiogenic isotopes, together with the result of the PCA calculation, suggests that the large-scale variation is unrelated to the plume–ridge interactions in the area and should rather be attributed to the partial melting of a marble-cake assemblage.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.epsl.2010.12.007DOIArticle
ORCID:
AuthorORCID
Thomas, Marion Y.0000-0002-4335-8841
Additional Information:© 2010 Elsevier B.V. Received 21 July 2010; revised 21 November 2010; accepted 1 December 2010. Editor: R.W. Carlson. Available online 31 December 2010. The Pb isotope work was funded by CNRS/INSU. The Hf isotope work was supported by NSF grants to B.B. Hanan. We thank Joan Miller for technical assistance at SDSU. We acknowledge Rick Carlson for the editorial handling, Francis Albarède and an anonymous reviewer for constructive comments. Cedric Hamelin thanks the Caltech Tectonic Observatory for its hospitality during his stay in Pasadena. We gratefully acknowledge Neus Sabater for her valuable comments.
Funders:
Funding AgencyGrant Number
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
NSFUNSPECIFIED
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Subject Keywords:oceanic basalts; Pacific-Antarctic Ridge; mantle heterogeneity; Principal Component Analysis; Sr Nd Pb Hf isotopes
Issue or Number:1-2
Record Number:CaltechAUTHORS:20110317-130410278
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20110317-130410278
Official Citation:Cedric Hamelin, Laure Dosso, Barry B. Hanan, Manuel Moreira, Andrew P. Kositsky, Marion Y. Thomas, Geochemical portray of the Pacific Ridge: New isotopic data and statistical techniques, Earth and Planetary Science Letters, Volume 302, Issues 1-2, 1 February 2011, Pages 154-162, ISSN 0012-821X, DOI: 10.1016/j.epsl.2010.12.007.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22959
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:18 Mar 2011 14:43
Last Modified:03 Oct 2019 02:42

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