From Source to Sink: Petrogenesis of Cretaceous Anatectic Granites from the Fosdick Migmatite-Granite Complex, West Antarctica

• Published in: Journal of Petrology
• Main Authors: Brown, Caitlin R, Yakymchuk, Chris, Brown, Michael, Fanning, Christopher Mark, Korhonen, Fawna J., Piccoli, Philip M., Siddoway, Christine S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press 2016
• Subjects: cumulate granite; Hf and O isotope geochemistry; migmatite; Nd-Sr isotope geochemistry; zircon; West Antarctica; Fanning; Korhonen; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10012/13369; https://doi.org/10.1093/petrology/egw039

This is a pre-copyedited, author-produced version of an article accepted for publication in Journal of Petrology following peer review. The version of record Brown, C. R., Yakymchuk, C., Brown, M., Fanning, C. M., Korhonen, F. J., Piccoli, P. M., & Siddoway, C. S. (2016). From Source to Sink: Petrogenesis of Cretaceous Anatectic Granites from the Fosdick Migmatite–Granite Complex, West Antarctica. Journal of Petrology, 57(7), 1241–1278 is available online at: https://doi.org/10.1093/petrology/egw039 Anatectic granites from the Fosdick migmatite-granite complex yield U-Pb zircon crystallization ages that range from 115 to 100Ma, with a dominant grouping at 107-100 Ma, which corresponds to the timing of dome formation during the regional oblique extension that facilitated exhumation of the complex. The occurrence of leucosome-bearing normal-sense shear zones inmigmatitic gneisses indicates that suprasolidus conditions in the crust continued into the early stages of doming and exhumation of the complex. The structure allows access to variably oriented granites in networks of dykes at deeper structural levels and subhorizontal sheeted granites at shallower structural levels within the complex. This feature allows an evaluation of the mechanisms that modify the composition of granite melts in their source and of granite magmas during their ascent and emplacement using whole-rock major, trace element and Sr and Nd isotope compositions, zircon Hf and O isotope compositions, and phase equilibria modelling of potential source rocks. Geochemical variability within the granites is attributed to source heterogeneity and blending of melts, which themselves are consistent with derivation from regional metasedimentary and metaplutonic source materials. The granites typically contain coarse blocky K-feldspar and/or plagioclase grains within interstitial quartz, and have low Rb/Sr ratios and large positive Eu anomalies. These features are inconsistent with the composition of primary crustal melts derived from ...