New age constraints for orogenic collapse and voluminous late-tectonic magmatism in the southern part of the East African-Antarctic Orogen

• Main Authors: Jacobs, J., Thomas, Robert James, Bauer, W., Engvik, A., Laufer, A., Wingate, M.
• Format: Conference Object
• Language: English
• Published: National Academies Press 2008
• Subjects: Earth Sciences; Antarctic; Dronning Maud Land; Antarc*
• Online Access: http://nora.nerc.ac.uk/id/eprint/5600/; https://nora.nerc.ac.uk/id/eprint/5600/1/Jacobs_et_al_2007.pdf; http://isaes2007.geol.ucsb.edu/

The southern third of the more than 8000 km long, Late Neoproterozoic/Early Paleozoic East African- Antarctic Orogen in Dronning Maud Land and northern Mozambique is characterised by lateral extrusion, late tectonic extensional shearing and large volumes of late tectonic igneous rocks. We provide new SHRIMP data for extensional shearing and the timing of late-tectonic igneous activity. The new geochronological ages for the late tectonic granitoid intrusions range between 508-500 Ma, whilst metamorphism along a significant extensional shear zone was dated at c. 510 Ma. The granitoids are part of a > 15,000 km2 large igneous province that can be traced to the Lurio Belt in northern Mozambique. The granitoids have A2-type geochemistry and are thought to represent lower crustal partial melting, that probably resulted from asthenosphere influx after part of the orogen root had delaminated. The northern margin of this large igneous province appears as a tectonic boundary, the Lurio Belt.