2003 Seattle Annual Meeting (November 25, 2003)
Paper No. 110-3
Presentation Time: 2:05 PM-2:20 PM

AFRICA WITHIN RODINIA SUPERCONTINENT: EVIDENCE FROM THE KIBARAN OROGENIC SYSTEM

KAMPUNZU, A.B.1, MILESI, J.P.2, and DESCHAMPS, Y.2, (1) Department of Geology, Univ of Botswana, Botswana, Botswana, Kampunzu@mopipi.ub.bw, (2) B.R.G.M., BP 6009, 45060 Orleans Cedex 2

The Mesoproterozoic Kibaran orogenic system of Africa has been ignored in most Rodinia reconstruction scenarios. This orogenic belt extends for >3000 km and is >400 km wide in Africa. It is the result of the convergence of Paleoproterozoic/Archaean cratonic blocks forming the Congo craton to the north and a mosaic including the Kalahari, Bangweulu, Tanzania and West-Nilian cratons (hereafter Kalahari craton) to the south. The orogenic system includes several segments with local names (from north to south): Karagwe-Ankolean, Burundian, Kibarides, Irumides, Choma-Kalomo, Ngamiland, Namaqua-Natal and Lurio belts. These segments define two major groups: (1) provinces affected by a long-lived Mesoproterozic plate convergence between ~1.4-1.0Ga. They host sedimentary basins affected by contractional deformation for the first time during the Mesoproterozoic. The supracrustal sedimentary units are intruded by large batholiths with peak magmatism/deformation at ca. 1.39-1.35 Ga (subduction) and 1.1-1 Ga (continental collision). Geochemical characteristics of 1.39-1.35 Ga mafic rocks suggest an active continental margin, although an ophiolitic complex formed in an oceanic arc has been documented. Strongly peraluminous Sn-Nb-W-REE bearing collisional granites were emplaced at ca. 1-0.96 Ga. (2) Archaean to Paleoproterozoic provinces representing older crust of the converging plates strongly reworked during the 1.1-1 Ga continental collision. Thin-skinned folds-thrusts define the main physiography of this orogen in central-eastern Africa and control the NE-SW structural grain of the belt.

The above new geological and geochronological data and interpretations suggest the convergence between the Kalahari craton and a composite Congo-Laurentia craton during the assembly of Rodinia, generating the Kibaran-Grenvillian-Llano belts. IGCP 440 geological and paleomagnetic data will be used to further constrain this interpretation.

2003 Seattle Annual Meeting (November 25, 2003)
Session No. 110
Testing Rodinia Using New Maps Compiled for Each Craton through IGCP 440
Washington State Convention and Trade Center: 615/616/617
1:30 PM-5:30 PM, Monday, November 3, 2003

Geological Society of America Abstracts with Programs, Vol. 35, No. 6, September 2003, p. 301

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