The age and origin of younger granitic plutons of the Shaw Batholith in the Archaean Pilbara Block, Western Australia

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Authors:Bickle, M. J.; Bettenay, L. F.; Chapman, H. J.; Groves, D. I.; McNaughton, N. J.; Campbell, I. H.; De Laeter, J. R.
Author Affiliations:Primary:
Univ. Cambridge, Dep. Earth Sci., GB-Cambridge CB2 3EQ, United Kingdom
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 101(3), p.361-376. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1989
Note:In English. 37 refs.; illus. incl. 11 tables, geol. sketch maps
Summary:The whole-rock Pb-Pb method was used to date four of the younger, mainly adamellite, late-tectonic plutonic phases within the 3500 m.y. Shaw batholith. Three suites give ages within error of 2966 m.y. (porphyritic granites at 2948 +- m.y., leuco-adamellites at 2943 +- 46 m.y., and Garden Creek adamellite 3007 +- 48 m.y.). The post-tectonic Cooglegong adamellite gives an age of 2847 +- 34 m.y. The Sm-Nd model systematics of all four suites indicate derivation from crust ranging in age between approx 3200 and 3600 m.y. The sources for these four younger plutonic phases were heterogeneous and, although exhibiting some isotopic characteristics of the older (3005-3003 m.y.) calc-alkali plutonic suites, were more depleted in LIL elements Rb, U and Th. In addition, the Garden Creek adamellite and the Cooglegong adamellite lack the very fractionated and HREE-depleted REE patterns characteristic of both the older calc-alkali plutonic rocks and the porphyritic granites and leuco-adamellites. The crust underlying the Shaw Batholith at approx 2950 m.y. must have been both markedly heterogeneous and variably depleted, a conclusion consistent with the complex tectonic and plutonic evolution of this region. [P.Br.]
Subjects:Absolute age; Adamellite; Batholiths; Chemical composition; Dates; Genesis; Granites; Igneous rocks; Intrusions; Isochrons; Pb/Pb; Petrology; Plutonic rocks; Porphyry; Rb/Sr; Australasia; Australia; Pilbara Craton; Western Australia; Shaw Batholith
Abstract Numbers:89M/4610
Record ID:1989067696
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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