Noritic dykes of southern West Greenland: early Proterozoic boninitic magmatism

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Authors:Hall, R. P.; Hughes, D. J.
Author Affiliations:Primary:
Portsmouth Polytech., Dep. Geol., GB-Portsmouth, PO1 3QL, United Kingdom
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 97(2), p.169-182. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1987
Note:In English. 102 refs.; illus. incl. 52 anal., 5 tables, geol. sketch map, charts
Summary:Two major swarms of early Proterozoic (approx 2100 m.y.) basic dykes occur within the Archaean craton in this area. One swarm comprises ophitic and sub-ophitic tholeiitic dolerites, while the other (the BN dyke swarm) consists mainly of norites in which pyroxenes and olivine are enclosed by plagioclase. The BN dykes are geochemically distinctive, most having high MgO (approx 16%), Cr and Ni, with relatively high SiO2, LREE and LIL element concentrations. The texture, mineral chemistry and petrochemistry in a quenched norite dyke all bear strong resemblances to those features in modern boninitic lavas. The BN dykes also correspond with proposed parental liquids of the Bushveld complex and other major layered basic igneous intrusions. The tholeiitic dykes were derived from a relatively undepleted, primordial mantle while the noritic dykes originated from a metasomatized harzburgite source. The widespread distribution of similar Proterozoic intrusions suggests crustal underplating by harzburgite mantle on a world- wide scale at this time. [R.A.H.]
Subjects:Andesites; Augite; Boninite; Chain silicates; Chemical composition; Chromite; Clinopyroxene; Diabase; Dike swarms; Dikes; Gabbros; Genesis; Geochemistry; Igneous rocks; Intrusions; Major elements; Nesosilicates; Norite; Olivine; Olivine group; Orthosilicates; Oxides; Petrology; Pigeonite; Plutonic rocks; Precambrian; Proterozoic; Pyroxene group; Silicates; Upper Precambrian; Volcanic rocks; Arctic region; Greenland; West Greenland; Igneous activity
Abstract Numbers:88M/5623
Record ID:1988041495
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe
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