Title: Petrology and Chemistry of Lavas from Seamounts Flanking the East Pacific Rise Axis, 21°N°: Implications Concerning the Mantle Source Composition for Both Seamount and Adjacent EPR Lavas
Abstract: Petrology and Chemistry of Lavas from Seamounts Flanking the East Pacific Rise Axis, 21°N°: Implications Concerning the Mantle Source Composition for Both Seamount and Adjacent EPR Lavas James F. Allan, James F. Allan Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201Search for more papers by this authorRodey Batiza, Rodey Batiza Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201Search for more papers by this authorPeter Lonsdale, Peter Lonsdale Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, California 92093Search for more papers by this author James F. Allan, James F. Allan Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201Search for more papers by this authorRodey Batiza, Rodey Batiza Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201Search for more papers by this authorPeter Lonsdale, Peter Lonsdale Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, California 92093Search for more papers by this author Book Editor(s):Barbara H. Keating, Barbara H. KeatingSearch for more papers by this authorPatricia Fryer, Patricia FryerSearch for more papers by this authorRodey Batiza, Rodey BatizaSearch for more papers by this authorGeorge W. Boehlert, George W. BoehlertSearch for more papers by this author First published: 01 January 1987 https://doi.org/10.1029/GM043p0255Citations: 16Book Series:Geophysical Monograph Series AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary The 1982 PLUTO expedition collected lava samples from 3 seamounts and two small pillow cones that flank the East Pacific Rise near 21°N on crust 2.5–8×105 years old. The lavas are typically aphyric to porphyritic N-type and T-type MORBs, with a range in Mg# of 0.68–0.46, 1.1–2.1% TiO2, 13.8–17.7% Al2O3, 9.9–12.6% CaO, 2.5–4.0% Na2O, 10–190 ppm Ni, 1.8–8.1 ppm La, and (La/Sm)N of 0.36–1.22. Phenocrysts assemblages are pl+ol, pi, or ol+pl, with groundmass clinopyroxene and ground mass titanomagnetite as common phases. Cr-spinel may occur as inclusions in olivine or plagioclase or as loose crystals in the groundmass. The lavas from two of the seamounts, Green and Red, define distinct fractionation trends in CaO/Al2O3 vs Mg# and Na2O/(Na2O+CaO) vs Mg#. These trends are not correlated with (La/Sm)N, effectively precluding the derivation of lavas from these seamounts from a single bulk source. Lavas from individual volcanoes and from the entire data set define binary mixing lines when considering the REE, LILE, and HIFS, consistent with a mixed source of enriched and depleted material. Variable (La/Sm)N and sparse 87Sr/86Sr and 143Nd/144Nd data are consistent with source trace element heterogeneity for individual seamounts; the differing fractionation trends and the differing parental lavas that they require within individual seamounts may be related to either or both major element and mineralogical (i.e., spinel Iherzolite vs plagioclase Iherzolite) source heterogeneity. Comparable trace element data show that the seamount lavas are more diverse than the 21°N EPR lavas (seamount Ti/Zr is 65–215, EPR Ti/Zr is 84–107). The youthfulness of the seamount lavas (Late Pleistocene) and the proximity of the seamounts to the EPR imply that the seamount and adjacent EPR lavas share a common source, one that has compositional heterogeneities volumetrically large enough to be preserved in the seamount lavas. Citing Literature Seamounts, Islands, and Atolls, Volume 43 RelatedInformation
Publication Year: 2013
Publication Date: 2013-03-18
Language: en
Type: book-chapter
Indexed In: ['crossref']
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Cited By Count: 32
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