The source of A-type magmas in two contrasting settings: U-Pb, Lu-Hf and Re-Os isotopic constraints

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dc.contributor.authorPankhurst, M.J.
dc.contributor.authorSchaefer, B.F.
dc.contributor.authorTurner, S.P.
dc.contributor.authorArgles, T.
dc.contributor.authorWade, C.E.
dc.date.issued2013
dc.description.abstractThe sources of post-orogenic A-type magmas from two distinct geodynamic settings are compared. The end of the ca. 514–480 Ma Delamerian Orogeny, southeastern South Australia, was marked by ~ 10 Myr of bimodal A-type magmatism, driven by convective removal of thickened lithosphere. Initial Os and Hf isotope ratios record a heterogeneous lithospheric mantle source, with some input from aesthenospheric mantle. Mafic parental melts fractionated to produce the granites. In contrast, initial Os isotope ratios of the A-type magmas that comprise the ca. 1598–1583 Ma Mesoproterozoic Gawler Felsic Large Igneous Province, central South Australia, record a dominant evolved lower crust component. However, initial Hf isotope ratios from these samples are depleted, indicating a mantle source for lithophile elements. This voluminous, bimodal magmatism lasted for ~ 15 Myr, and ended the Wartakan Orogeny. In both cases the homogenisation of chemical (rheological) heterogeneities, inherited from terrain amalgamation and orogenic thickening, strengthened the lithosphere. The contemporaneous fusion of heterogeneous mantle ± crust may represent a common, stabilising influence on the lithospheric column regardless of tectono-magmatic setting.
dc.description.statementofresponsibilityM.J. Pankhurst, B.F. Schaefer, S.P. Turner, T. Argles, C.E. Wade
dc.identifier.citationChemical Geology, 2013; 351:175-194
dc.identifier.doi10.1016/j.chemgeo.2013.05.010
dc.identifier.issn0009-2541
dc.identifier.issn1872-6836
dc.identifier.orcidWade, C.E. [0000-0003-2569-2771]
dc.identifier.urihttp://hdl.handle.net/2440/117659
dc.language.isoen
dc.publisherElsevier
dc.rights© 2013 Elsevier B.V. All rights reserved.
dc.source.urihttps://doi.org/10.1016/j.chemgeo.2013.05.010
dc.subjectRe-Os isotopes; A-type; Lu-Hf isotopes; post-orogenic; geodynamics; lithospheric stabilisation
dc.titleThe source of A-type magmas in two contrasting settings: U-Pb, Lu-Hf and Re-Os isotopic constraints
dc.typeJournal article
pubs.publication-statusPublished

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