Geochronology and tectonic setting of voluminous granitoids and related rocks and associated extensional structures in Dronning Maud Land (East Antarctica)

Abstract

The history of the tectonic evolution in central Dronning Maud Land (cDML), East Antarctica can be inferred from various zircon grains for U-Pb zircon age determination with the Laser-Ablation Inductively-Coupled-Plasma Mass Spectrometry (LA-ICP-MS) technique. The zircons grain of the different rocks collected from different geographic location in cDML include the Shcherbakova area, the Holtedahlfjella and Zwiesel area. New zircon U-Pb ages have been used to establish relationships between ancient rocks, to obtain new insights into the Early Paleozoic orogenic collapse and contemporaneous voluminous late-tectonic intrusions in central Dronning Maud Land. Most of these results agree reasonably well with the supercontinent assemblage chronology of Gondwana within the cDML. The oldest ages of 1100 Ma to 910 Ma correspond to the final construction of the Rodinia. The ages of 900 Ma to 620 Ma are likely to represent a number of rifting events that are associated with the destruction of Rodinia. The U-Pb zircon ages of 610 Ma to 535 Ma corresponds with the re-assemblage of parts of E and W- Gondwana during the East-African orogeny. The youngest ages of 530 Ma to 458 Ma correspond to the Pan-African orogeny and thus the final amalgamation of Gondwana. Grenville-age rocks of ~ 1100Ma represent the oldest basement yet found in cDML that was during large-scale delamination intruded by the late-tectonic granitoids. A detrital zircon age of 950-680 Ma found in one sample of the cDML is reported from this area outside of the Schirmacher Oasis for the first time in this study.