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Geochemical consequences of flow differentiation in a multiple injection dike (Trinity ophiolite, N. California)

LITHOS

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DOI: 10.1016/0024-4937(91)90031-F

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Abstract

A clinopyroxene-rich dike of the Trinity ophiolite sheeted-dike complex shows three different magmatic pulses, probably injected in a short period of time (no well developed chilled margin) and important variations of the clinopyroxene and plagioclase percentages between its core (highly porphyritic) and margins (aphyric). This variation, interpreted as related to a flow differentiation phenomenon (mechanical phenocryst redistribution), has important geochemical consequences. It produces increases in the FeO, MgO, CaO, Cr and Ni contents from the margin to the core, together with increases in the clinopyroxene percentage, and decreases in the SiO2, Zr, Y, Nb and REE contents together with a decrease in the percentage of the fine-grained groundmass toward the core of the dike. This mineralogical redistribution, which also affects the incompatible trace element ratios because of the difference in plagioclase and clinopyroxene mineral/liquid partition coefficients, illustrate the importance of fractionation processes outside of a magma chamber. ?? 1991.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Geochemical consequences of flow differentiation in a multiple injection dike (Trinity ophiolite, N. California)
Series title:
LITHOS
DOI:
10.1016/0024-4937(91)90031-F
Volume
26
Issue:
3-4
Year Published:
1991
Language:
English
Publisher:
Elsevier
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
245
Last page:
252
Number of Pages:
8