Title Early Palaeozoic orogenic collapse and voluminous late-tectonic magmatism in Dronning Maud Land and Mozambique; insights into the partially delaminated orogenic root of the East African-Antarctic Orogen?
Author Jacobs, J.; Bingen, B.; Thomas, R.J.; Bauer, W.; Wingate, M.T.D.; Feitio, P.
Author Affil Jacobs, J., University of Bergen, Department of Earth Science, Bergen, Norway. Other: National Institute of Polar Research, Japan; Kyushu University, Japan; Chiba University, Japan; Geological Survey of Norway, Norway; British Geological Survey, United Kingdom; Geological Survey of Western Australia, Australia; Direcao Nacional Geologia, Mozambique
Source Geodynamic evolution of East Antarctica; a key to the east-west Gondwana connection, edited by M. Satish-Kumar, Y. Motoyoshi, Y. Osanai, Y. Hiroi and K. Shiraishi. Geological Society Special Publications, Vol.308, p.69-90, . Publisher: Geological Society of London, London, United Kingdom. ISSN: 0305-8719. ISBN: 978-1-86239- 268-7
Publication Date 2008
Notes In English. 59 refs. Ant. Acc. No: 85814
Index Terms Antarctica--East Antarctica; Mozambique; Antarctica--Queen Maud Land; absolute age; Africa; Antarctica; crust; dates; delamination; East Africa; East Antarctica; Gondwana; igneous rocks; International Polar Year 2007-08; IPY 2007-08 Research Publications; lower Paleozoic; magmatism; metamorphic rocks; metamorphism; models; Nampula Province; Neoproterozoic; nesosilicates; orogeny; orthosilicates; paleogeography; Paleozoic; plate collision; plate tectonics; plutonic rocks; Precambrian; Proterozoic; Queen Maud Land; roots; silicates; tectonics; terranes; titanite; titanite group; U/Pb; upper Precambrian; zircon; zircon group
Abstract The late tectonic history of the southern part of the Late Neoproterozoic- Early Palaeozoic East African-Antarctic Orogen (EAAO) is characterized by lateral extrusion, extensional collapse and large volumes of high-temperature A2-type granitoids. This late-tectonic igneous province covers an area more than 15 000 km2 of the EAAO in Dronning Maud Land (East Antarctica) and its northerly continuation as the Nampula Complex of NE Mozambique. The magmatic province is bounded in the north by the Lurio Belt. New secondary ionization mass spectrometry (SIMS) U-Pb analyses of zircons from two major late-tectonic granitoid intrusions from Dronning Maud Land indicate crystallization ages of 5017 and 4994 Ma, whereas a major extensional shear zone was dated at 5079 Ma. New SIMS zircon U-Pb analyses of late-tectonic granitoid sheets and plutons from the Nampula Province indicate ages of 5124, 5084, 5082 and 5073 Ma. Consequently, the late-tectonic magmatism can be bracketed between c. 530 and 485 Ma. It started with small gabbro bodies emplaced at c. 530-520 Ma, culminated with the intrusion of major granite-charnockite plutons at c. 510-500 Ma and terminated with the introduction of small volumes of sheet- like granite at c. 485 Ma. The new dates demonstrate that extensional shearing and granitoid intrusion are synchronous, and that orogenic collapse and the magmatism are related. We ascribe the distribution, structural style, geochemical composition and age of the late magmatic province to a process of partial delamination of the orogenic root in the southern third of the EAAO. It remains to be tested whether there is a relationship between orogenic collapse- granitoid magmatism and south-directed escape tectonics in the southernmost EAAO.
URL http://hdl.handle.net/10.1144/SP308.3
Publication Type journal article
Record ID 290793