| Paper No. 63-0 | ||
| UMKONDO IGNEOUS PROVINCE AND MESOPROTEROZOIC UMKONDO BASIN IN EASTERN ZIMBABWE: POSSIBLE RELEVANCE TO RODINIA | ||
|
MUKWAKWAMI, Joshua1, BLENKINSOP, Tom G.1, HANSON, Richard2, and MUNYANYIWA, Hubbert1, (1) Department of Geology, Univ of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe, joshua@science.uz.ac.zw, (2) Geology, Texas Christian Univ, Box 298830, Fort Worth, TX TX 76129 The Umkondo igneous province in southern Africa may record impact of a mantle plume on the Kalahari craton during Rodinia assembly at 1.1 Ga, coinciding with widespread intraplate magmatism in Laurentia. In the Umkondo type area, eastern Zimbabwe, dolerite dykes and extensive sills (>=100 m thick) intrude metasedimentary rocks of the Umkondo Group, which forms a sequence up to 800 m thick of basal arkoses, stromatolitic limestones, cherts, mudrocks and quartzose sandstones. The metasedimentary rocks are locally folded about N-S axes and thrust towards the west, and have been metamorphosed with the dolerites at low grade. This tectonism probably occurred during Pan-African orogenesis. The age and tectonic setting of the Umkondo basin are not well established, but it may have linked with a Mesoproterozoic continental margin to the east. The Umkondo strata rest non-conformably on the Archean basement. Dolerite sills are continuous from the basement into the Umkondo Group; some sills were intruded along the nonconformity. Probable felsic tuffs and mafic lapilli tuffs occur in the middle Umkondo Group, which is conformably overlain by basalt lavas geochemically similar to the dolerites. Together with the presence of peperite along one sill margin, these observations suggest that deposition of the Umkondo Group directly preceded widespread Umkondo mafic magmatism. The Umkondo Group appears to have been deposited in fluvial to shallow-water environments with episodic input of distal bimodal pyroclastic debris. Lateral continuity of the main stratigraphic units suggests a single depositional basin with a N-S dimension >=390 km. These preliminary observations may have paleogeographic implications for Rodinia reconstructions. | ||
|
GSA Annual Meeting, November 5-8, 2001
General Information for this Meeting | ||
| Session No. 63 Focus on IGCP: Modern and Ancient Plate Boundaries and Orogens I: In Memory of Chris McA. Powell Hynes Convention Center: 100 8:00 AM-12:00 PM, Tuesday, November 6, 2001 | ||
© Copyright 2001 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions. | ||