U–Pb and Hf-isotope analyses of zircon from the Kundelungu Kimberlites, D.R. Congo: Implications for crustal evolution

Abstract

The Gungwania and Talala kimberlitic pipes on the Kundelungu Plateau (Katanga, SE Congo) have been used as drillholes, to obtain crustal zircons for a study of crustal evolution in the region and to constrain the age of the basement and the sedimentary provenance of the Katangan Supergroup. Two hundred and twenty-nine zircon grains were analysed for U-Pb ages and Hf-isotope compositions. Juvenile Mesoarchean (∼3.4-3.3 Ga) crust in the region underwent recycling during Neoarchean and Paleoproterozoic time. The Paleoproterozoic event involved little production of juvenile crust, and this Paleoproterozoic crust was recycled during Mesoproterozoic and Neoproterozoic time. Both the Mesoproterozoic and Neoproterozoic were characterised by bimodal magmatism reflecting extension, linked with the break up of Rodinia and the opening of the Katangan basin, and the development of juvenile crust. Detailed studies of the external morphology of the zircons in different age groups suggest that the basement beneath the Kundelungu region is predominantly Paleoproterozoic in age; other zircon populations may be derived from the Katangan sediments. The absence of any zircons younger than 560 Ma supports deposition of the Biano Subgroup, which hosts the kimberlites, during the Pan-African Lufilian orogeny. The Archean Congo and Zimbabwe cratons, the Paleoproterozoic Ubendian Belt (Bangweulu Block), the Paleo-to-Mesoproterozoic Irumide Belt, the Mesoproterozoic Kibaran Belt and the Choma Kalomo Block may all have contributed material to the sediments of the Katangan Supergroup.

U–Pb SHRIMP geochronology of zircon from the Catoca kimberlite, Angola: Implications for diamond exploration

“…Catoca kimberlite was expected to be younger than the carbonatites and alkaline rocks found in the Lucapa structure. These rocks yielded K-Ar and Rb-Sr ages between 138 and 130 Ma Cretaceous kimberlitic events of similar age have also been reported in the São Francisco craton (Brazil), the Kaapvaal craton (South Africa and Botswana), and the Congo-Kasai craton (the Democratic Republic of Congo), which were all part of Gondwanaland (e.g., Batumike et al, 2007;Jelsma et al, 2009). Systems of deep faults present in these cratons probably were the focus of thermal perturbations and injection of melt.…”

Unravelling a Proterozoic basin history through detrital zircon geochronology: The case of the Espinhaço Supergroup, Minas Gerais, Brazil

“…Mesoproterozoic Kibaran Orogenic System of central Africa developed between 1.4 and 0.95 Ga (from rifting to post collisional stage) situated in eastern part of the Congo Craton, with continental collision between 1250 and 1000 Ma (Kokonyangi et al, 2006;Batumike et al, 2007), could thus contribute to the increase of sedimentary rate in the Upper Espinhaço Intracratonic Basin, similar as described for the intracratonic basins in the Gondwana during the Permian and Carboniferous periods (e.g. Shaw et al, 1991;Milani and Ramos, 1998).…”

The time scales of continental rifting: Implications for global processes

“…3). During this same period, kimberlites were emplaced in Archean lithosphere between the Western and Eastern rift (Harrison et al, 2001), and fl anking the Southwestern rift (Batumike et al, 2007). Their widespread distribution suggests that heating and local metasomatism preceded any surface expression of rifting across the broad, uplifted plateaus.…”