Timing of Grenville-age vs. Pan-African medium- to high grade metamorphism in western Dronning Maud Land (East Antarctica) and significance for correlations in Rodinia and Gondwana
Date
2003
Authors
Jacobs, Jeffrey Bruce
Fanning, Christopher
Bauer, Wolfgang
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Heimefrontfjella in western Dronning Maud Land, East Antarctica, is part of the c. 1.1 Ga Namaqua-Natal-Maud Belt. It is situated at an important location, both for Rodinia reconstructions and at the western orogenic front of the Late Neoproterozoic/Early Palaeozoic East African/Antarctic Orogen. Six basement samples help to precisely date the Grenville-age metamorphism between c. 1090 and 1060 Ma. These dates indicate that palaeomagnetic data from the Coats Land Block to the south of the Maud Belt cannot be taken to support the contiguity of the Coats Land/Maud/Grunehogna continental fragment and Kalahari during Late Mesoproterozoic times. A comparison of aeromagnetic data and crustal provinces indicates that the Coats Land basement is likely to be composed of pre-Mesoproterozoic basement that was differentially reworked at c. 500 Ma within the East African/Antarctic Orogen. The western orogenic front of the East African/Antarctic Orogen is exposed as the Heimefront Shear Zone. Zircons from this shear zone show a thin, low-U, reaction zone that probably resulted from mylonitisation at amphibolite facies conditions. The rims were too thin to be analysed. However, only a few kilometres to the E of the shear zone, c. 500 Ma Pan-African zircon overgrowth is present, clearly indicating intense Late Neoproterozoic/Early Palaeozoic reworking of the Grenville-age basement and allowing the direct dating of this younger overprint. High grade reworking must have been followed by rapid cooling, as shown by a number of c. 500 Ma K-Ar and Ar-Ar hornblende and mica ages. Whereas the western orogenic front of the East African/Antarctic Orogen is exposed as the Heimefront Shear Zone, the eastern orogenic front might be represented by the Otter Highland Thrust in the Shackleton Range, with variably reworked crust up to granulite facies in between these two structural discontinuities.
Description
Keywords
Keywords: geochronology; Gondwana; Grenvillian orogeny; paleomagnetism; Proterozoic; reworking; Rodinia; article; comparative study; island biogeography; sample; Antarctica Grenville; Kalahari; Mesoproterozoic; Orogeny; U-Pb SHRIMP; Zircon
Citation
Collections
Source
Precambrian Research
Type
Journal article
Book Title
Entity type
Access Statement
License Rights
Restricted until
2037-12-31
Downloads
File
Description