Petrogenesis of picrites from the Caribbean Plateau and the North Atlantic magmatic province

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doi: 10.1016/S0024-4937(99)00038-9
Author(s): Révillon, S.; Arndt, N. T.; Hallot, E.; Kerr, A. C.; Tarney, J.
Author Affiliation(s): Primary:
CNRS Géosciences Rennes, Rennes, France
Other:
University of Leicester, Leicester, United Kingdom
Volume Title: Lithos (Oslo)
Source: Lithos (Oslo), 49(1-4), p.1-21. Publisher: Elsevier, Amsterdam, International. ISSN: 0024-4937 CODEN: LITHAN
Note: In English. 38 refs.; illus., incl. 5 tables, geol. sketch maps
Summary: We studied the petrography, mineralogy and geochemistry of picrites from three different regions: the island of Curacao which forms part of a Cretaceous oceanic plateau; Iceland, an active hot spot on the mid-Atlantic ridge; and the early Tertiary volcanic margin off the coast of Greenland, which formed during the rifting that created the Atlantic ocean. Using the compositions of olivine phenocrysts and relations between MgO and FeO, Al2O3 and Ni, we estimated compositions of parental liquids and the proportion of accumulated olivine in each rock. Picrites from Curacao formed mainly from a liquid with 12 wt.% MgO and they contain up to 55 wt.% excess olivine in the form of phenocrysts. A small proportion of more forsterite-rich olivine grains are xenocrysts from a more magnesian source. Picrites from Iceland formed from a slightly less magnesian liquid but one with also about 12 wt.% MgO and they contain both olivine and plagioclase in the accumulated assemblage. Picrites from the Greenland volcanic margin formed from a liquid that was distinctly more magnesian, with up to 20 wt.% MgO. In some of these rocks the proportion of accumulated olivine was minimal and in these the whole-rock composition is roughly equivalent to the liquid composition. The picrites from the three areas formed under different conditions and through contrasting melting processes. The Curacao picrites derive from pooled liquids formed through moderate degrees of melting at moderate depths beneath a relatively old and thick oceanic lithosphere. Iceland picrites, on the other hand, formed through advanced fractional melting of mantle that ascended almost to the base of the crust at the mid-ocean spreading center. An unusual combination of relatively high concentrations of incompatible trace elements and high MgO indicates that the Greenland picrites formed by relatively low degrees of melting at greater depths in the mantle. Abstract Copyright (1999) Elsevier, B.V.
Year of Publication: 1999
Research Program: ODP Ocean Drilling Program
Key Words: 05 Petrology, Igneous and Metamorphic; Antilles; Arctic region; Basalts; Caribbean Plateau; Caribbean region; Cenozoic; Chemical composition; Cretaceous; Curacao; Depth; Europe; Genesis; Greenland; Iceland; Igneous rocks; Leg 152; Lesser Antilles; Magmas; Magmatism; Mantle; Mass spectra; Melting; Mesozoic; Mineral composition; Netherlands Antilles; Ocean Drilling Program; Petrography; Picrite; Spectra; Tertiary; Trace elements; Ultramafic composition; Volcanic rocks; West Indies; Western Europe; X-ray fluorescence spectra
Coordinates: N624012 N632930 W0372737 W0394939
Record ID: 1999071090
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands