The age and chemistry of granitic gneisses from the western H.U. Sverdrupfjella, Maud Terrane, western Dronning Maud Land, Antarctica

Abstract

Mesoproterozoic magmatism has contributed extensively to the concept of a Rodinian Supercontinent with Sverdrupfjella, Dronning Maud Land, East Antarctica occupying a central position in a magmatic belt extending from Sri Lanka in the east to Namaqualand in the west. Age constraints based on UPb zircon data, combined with Sr, Nd and Hf data, from western Sverdrupfjella, are sparse with a new Mesoproterozoic dataset presented here. The Jutulrøra and Roerkulten granites in the Maud Terrane, have ages of ca. 1085 Ma, ca. 55 Myr younger than the ca. 1140 Ma arc-related tonalitic Jutulrøra Gneiss they intrude. Unlike the Jutulrøra Gneiss, which has Paleoproterozoic-Archaean Nd TDM ages, the Jutulrøra and Roerkulten granites have relatively juvenile Nd TDM ages, Hf TDM ages and εNd 1080Ma and Sri 1080Ma characteristics comparable to the on-craton ca. 1108 Ma dolerite sills of the Borgmassivet Suite, correlated with the Umkondo LIP of southern Africa. The Brekkerista Granite, located ca. 100 km E of the Grunehogna Craton in the Maud Terrane, has an Archaean age of ca. 2850 Ma and has Archaean Nd TDm and Hf 2 stage TDm zircon ages of ca. 3.2 and 3.4 Ga respectively.The ages and chemistry of the three granites, previously assumed to be Mesoproterozoic in age and related to the continental arc setting of the Maud Belt, confirm Archaean crust underlying the Maud Belt in Sverdrupfjella and also suggest the 1085 Ma granite magmatism in the Maud Belt may be either be related to the intracratonic ca. 1108 Ma Umkondo LIP, or marginally younger ca. 1090 Ma A-type magmatism, rather than the older ca. 1140 Ma arc orogenic accretionary setting previously inferred. The data are discussed with reference recent correlations between the timing and proximity of Laurentia to the Kalahari Craton.In paleogeographic reconstructions, the ca. 2850 Ma Brekkerista Granite is similar to basement gneiss from Pietersburg province, northern Kaapvaal Craton, southern Africa. In contrast the ca. 3100 Ma Annandagstoppane Granite, ca. 200 km WSW of Sverdrupfjella. underlying the Grunehogna Craton, is comparable to Barberton province granites, southeastern Kaapvaal Craton.