Isotope geochemistry and petrology of granitoid suites from Granite Harbour Intrusives of the Wilson Terrane, North Victoria Land, Antarctica
Armienti, Pietro; Ghezzo, Claudio; Innocenti, Fabrizio; Manetti, Piero; Rocchi, Sergio; Tonarini, Sonia
European Journal of Mineralogy Volume 2 Number 1 (1990), p. 103 - 124
published: Mar 8, 1990
manuscript accepted: Oct 26, 1989
manuscript received: Jul 18, 1989
ArtNo. ESP147050201012, Price: 29.00 €
Abstract The Granite Harbour Intrusives (GHI) are an orogenic association, with a petrogenetic affinity varying from high-K calc-alkaline to shoshonitic, that invaded the Wilson Terrane during Cambro-Ordovician times. Between David and Campbell Glaciers, they constitute three distinct intrusives complexes ; from South to North: the South Victoria Land Intrusives (SVLI), the Mt Abbott Intrusives (MAI) and the Deep Freeze Range Intrusives (DFRI). Fractionation processes in a closed system adequately model mineralogical, isotopic and major and trace element variations for SVLI and MAI, with the most evolved magmas representing 20-30 % of an initial dioritic melt. For the DFRI, the highly variable Sr and Nd initial (510 Ma) isotopic ratios (0.70649÷0.71130 and 0.51151÷0.51174 respectively), as well as the scattered major and trace element and REE patterns, suggests that this batholith was generated by geochemically distinct magma pulses that evolved locally by fractional crystallization. eSr and eNd indicate that GHI were derived by the interaction of a mantle and a crustal component, whose proportion varies between 40 and 70 %. The lower crust of this sector of North Victoria Land can be considered of early Proterozoic to Archean age on account of the Nd model ages of outcropping undepleted granulites (TDM = 1.9 ÷ 2.0 Ga) and of granitoid rocks, mainly in the range 1.7 ÷ 2.1 Ga.