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Gijs Straathof, University of Edinburgh (United Kingdom)
Jenny Tait, University of Edinburgh (United Kingdom)
Emmanuel Cibambula, Université de Kinshasa (Congo, the Democratic Republic of the)
Valentin Kanda Nkula, Université de Kinshasa (Congo, the Democratic Republic of the)
Udo Zimmermann, University of Stavanger (Norway)
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In order to better understand and constrain the Neoproterozoic periods of apparent extreme climate conditions we studied the West Congolian Group using a multidisciplinary approach. This succession is part of the West Congo belt, which extends subparallel to the Atlantic coast from Angola to Gabon. The West Congolian Group (ca 910-566 Ma) encloses the Lower and the Upper Mixtite Formations, which are previously associated with the Sturtian and the Marinoan events respectively. Siliclastic and carbonate rocks, together with a basaltic unit are found around these horizons of diamictite. The whole succession shows a Greenschist facies metamorphic overprint in the west, which is decreasing towards the east. This metamorphic event is associated with the Pan-African orogeny and is the dominant process in giving the group's current structure.
In the Bas-Congo province in the Democratic Republic of Congo, the Upper Mixtite Formation varies in thickness from ca 1 - 20 m and is found with a pink dolomitised carbonate cover. Chemostratigraphy identifies isotopic values similar to those found across the Congo craton and other cratons around the world. Palaeomagnetic sampling was carried out for both sedimentary and volcanic rocks, associated with the diamictites. Analyses of these data will reveal latitudonal constraints on the position of the Congo craton during the Neoproterozoic with implications for the Snowball Earth scenario. Whole rock geochemical analysis tries to decipher the tectonic setting for the volcano-sedimentary succession and detrital zircon age dating is used to constrain a maximum sedimentation age.
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