What is it about?
Intrusive and metavolcanic rocks within the Zambezi supracrustal sequence of southern Zambia were dated using SHRIMP analysis of zircons. The deposition of the supracrustal sequence occurred between 880 million years (age of basal rhyolite volcanics) and 820 million years (age of intrusion of the Lusaka granite). The sedimentary rock sequence and chemistry of the volcanics suggests extension and rifting commenced at 880 Ma at the southern margin of the Congo craton.
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Why is it important?
If the Congo craton was once part of the Mesoproterozoic Rodinia supercontinent, the rifting at its southern margin at 880 Ma might represent one of the earliest dates for commencement of supercontinent breakup in the Neoproterozoic era.
Perspectives
The work demonstrates that the Zambezi supracrustal volcanosedimentary sequence is broadly coeval with the Roan Group at the base of the Katanga Supergroup.
Dr David M Evans
Natural History Museum, London
Read the Original
This page is a summary of: Geochronology of the Zambezi Supracrustal Sequence, Southern Zambia: A Record of Neoproterozoic Divergent Processes along the Southern Margin of the Congo Craton, The Journal of Geology, May 2007, University of Chicago Press,
DOI: 10.1086/512757.
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