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Rare earth and trace element geochemistry of a fragment of Jurassic seafloor, Point Sal, CaliforniaRocks from an ophiolite suite once on the seafloor were analyzed for rare earth elements (REE), Sc, Co, Na2O, Cr, Zn and FeO. Strontium isotope exchange noted in some of the lavas is attributed to basalt-seawater interaction; the Ce abundance in smectite- and zeolite-bearing lavas may also be due to prolonged exposure to seawater. The higher grades of metamorphic rock, however, show no variation from the usual flat or slightly light REE depleted profiles. Plutonic igneous rock, all light REE depleted, have total REE abundances varying by a factor of 100 between the dunites and diorites. In order of decreasing REE abundance are hornblende, clinopyroxene, plagioclase, orthopyroxene and olivine. Calculations of REE contents of liquids in equilibrium with early cumulative clinopyroxenes suggest that the parent to the stratiform sequence was more depleted in light REE than the parent to the lava pile.
Document ID
19780026537
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Menzies, M.
(California, University Davis, Calif., United States)
Blanchard, D.
(NASA Johnson Space Center Houston, Tex., United States)
Brannon, J.
(Lockheed Electronics Co., Inc. Houston, Tex., United States)
Korotev, R.
(Wisconsin, University Madison, Wis., United States)
Date Acquired
August 9, 2013
Publication Date
October 1, 1977
Publication Information
Publication: Geochimica et Cosmochimica Acta
Volume: 41
Subject Category
Geophysics
Accession Number
78A10446
Distribution Limits
Public
Copyright
Other

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