Tectonostratigraphic evolution coupled with climate changes of the pre-Sturtian Fungurume-Mwashya platform in the Tenke-Fungurume Mining District, Democratic Republic of the Congo

Pascal Mambwe, Franck Delpomdor, Sébastien Lavoie, Philippe Mukonki, Jacques Batumike, Philippe Muchez

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A tectonostratigraphic model is here proposed for the Fungurume-Mwashya platform succession at Tenke Fungurume Mining District (TFMD), south-east Democratic Republic of Congo. TFMD in the Katanga Copperbelt hosts the stratiform to stratabound Cu-Co mineralization. Sedimentary slumping and the generation of mass flows were principally controlled by tectonic activity during the initial rifting of the intracratonic Nguba Rift-Basin, around ~760-740 Ma. At least three tectonostratigraphic sequences recorded the tectonic reorganization between the Congo Craton and the Tanzanian block. One of them, which has been recognized at the base of the Mwashya Subgroup, has recently been coupled with the ~760-740 Kaigas glacial event. It is characterizedby a backstepping to shallowing-upward sequence capped by an erosion surface at the top of the Kansuki Formation. This sequence begins by deposition of the periglacial polygenetic conglomerate, the lateral stratigraphic equivalent of the Mwashya Conglomerate, and the post-glacial cap carbonate sequence of the Kamoya Formation (Fig.1). The Fungurume-Mwashya succession was deposited in a protected coastal lagoon adjacent to a tidal flat environment which was protected from the open sea by a barrier shoal (Cailteux et al., 2007; Mambwe et al., 2019). The platform was then flooded by fluvio-deltaic siliciclastics in the aftermath of the Sturtian glacial event. This is evidenced by the diamictitic facies of the Mwale Formation. Large amount of hematite within the matrix of the polygenic conglomerate recorded a remobilization of ferrous iron in bottom waters from the ~765-745 volcanic activity, which was oxidized by the mixing of layers of the stratified seawater at the onset of the Kaigas deglaciation. This bottom-water mixing was probably controlled by local fault-controlled uplift that generated subaqueous mass movements. The overlying cap carbonate sequence successively comprises an ~100 m-thick deepening-upward transgressive to shallowing-upward carbonate succession that was marked by deposition of oolites on the barrier platform top. It was followed by the development of lagoonal and tidal flat sediments during a sea-level highstand. This study concludes that the cycles of deposition in the Fungurume-Mwashya platform succession were driven by regional tectonics, superimposed upon the ~750-720 Ma Kaigas and ~717–660 Ma Sturtian glacial intervals (Mambwe et al., 2020).
Original languageEnglish (US)
Title of host publicationAbstract Book - Geologica Belgica Meeting 2021
StatePublished - 2021

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