Mineral composition of mid-ocean-ridge basalts from ODP Leg 187 sites

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Autor principal: Sato, Hiroshi
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Lenguaje:en
Publicado: PANGAEA 2004
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author Sato, Hiroshi
author_facet Sato, Hiroshi
collection Datos científicos de ciencias marinas y ambientales
contents The chemical compositions of olivine, plagioclase, pyroxene, and spinel in lavas collected during Ocean Drilling Program Leg 187 in the Australian Antarctic Discordance, Southeast Indian Ridge (41°-46°S, 126°-135°E) were analyzed, and modeling of the theoretical equilibrium petrogenetic conditions between olivine and melt was conducted. The cores of larger olivine phenocrysts, particularly in the isotopic Indian-type mid-ocean-ridge basalt (MORB), are not equilibrated with melt compositions and are considered to be xenocrystic. Larger plagioclase phenocrysts with compositionally reversed zonation are also xenocrystic. The compositions of primary magma were calculated using a "maximum olivine fractionation" model for primitive MORB that should fractionate only olivine. Olivine compositions equilibrated with calculated primary magma and compositions of calculated primary magma suggest that (1) isotopic Pacific-type MORB is more fractionated than Indian-type MORB, (2) Pacific-type MORB was produced by higher degrees of partial melting than Indian-type MORB, and (3) primary magma for Indian-type MORB was segregated from mantle at 10 kbar (~30 km depth), whereas that for Pacific-type MORB was segregated at 15 kbar (~45 km depth).
format Dataset Open Access
id pangaea_https___doi_org_10_1594_PANGAEA_780714
institution PANGAEA
language en
publishDate 2004
publisher PANGAEA
record_format pangaea
spellingShingle Mineral composition of mid-ocean-ridge basalts from ODP Leg 187 sites
Sato, Hiroshi
187-1153A; 187-1154A; 187-1155A; 187-1155B; 187-1156A; 187-1156B; 187-1157A; 187-1157B; 187-1158B; 187-1158C; 187-1160B; 187-1161A; 187-1161B; 187-1162A; 187-1164A; 187-1164B; DRILL; Drilling/drill rig; Indian Ocean; Joides Resolution; Leg187; Ocean Drilling Program; ODP
The chemical compositions of olivine, plagioclase, pyroxene, and spinel in lavas collected during Ocean Drilling Program Leg 187 in the Australian Antarctic Discordance, Southeast Indian Ridge (41°-46°S, 126°-135°E) were analyzed, and modeling of the theoretical equilibrium petrogenetic conditions between olivine and melt was conducted. The cores of larger olivine phenocrysts, particularly in the isotopic Indian-type mid-ocean-ridge basalt (MORB), are not equilibrated with melt compositions and are considered to be xenocrystic. Larger plagioclase phenocrysts with compositionally reversed zonation are also xenocrystic. The compositions of primary magma were calculated using a "maximum olivine fractionation" model for primitive MORB that should fractionate only olivine. Olivine compositions equilibrated with calculated primary magma and compositions of calculated primary magma suggest that (1) isotopic Pacific-type MORB is more fractionated than Indian-type MORB, (2) Pacific-type MORB was produced by higher degrees of partial melting than Indian-type MORB, and (3) primary magma for Indian-type MORB was segregated from mantle at 10 kbar (~30 km depth), whereas that for Pacific-type MORB was segregated at 15 kbar (~45 km depth).
title Mineral composition of mid-ocean-ridge basalts from ODP Leg 187 sites
topic 187-1153A; 187-1154A; 187-1155A; 187-1155B; 187-1156A; 187-1156B; 187-1157A; 187-1157B; 187-1158B; 187-1158C; 187-1160B; 187-1161A; 187-1161B; 187-1162A; 187-1164A; 187-1164B; DRILL; Drilling/drill rig; Indian Ocean; Joides Resolution; Leg187; Ocean Drilling Program; ODP
url https://doi.org/10.1594/PANGAEA.780714