Petrology, geochronology and emplacement model of the giant 1.37Ga arcuate Lake Victoria Dyke Swarm on the margin of a large igneous province in eastern Africa

Geophysical Identification and Characterization of Mafic-Ultramafic Intrusions in Plume Centre Regions

“…Arcuate lineaments were first recognized by Baterham et al (1983) and Chavez Gomez (2000); however it was not until recently that the full extent of the swarm became apparent from extensive aeromagnetic surveys. A continuation of the swarm is identified from aeromagnetic data on the southern edge of Lake Victoria, hosted in the Archean Tanzania Craton, and correlated across the lake where aeromagnetic surveys are lacking, forming a nearly 180⁰ semi-circular dyke swarm with an outer radius of roughly 500 km (Figure 34b; Mäkitie et al, 2014). Together, these dykes form the (Tack et al, 2008) with which the LVDS is similarly coeval (e.g.…”

“…Together, these dykes form the (Tack et al, 2008) with which the LVDS is similarly coeval (e.g. Maier et al, 2010;Mäkitie et al, 2014). Together, these form the c. 1380 Ma magmatism in the Lake Victoria region, which is part of the broader Kunene-Kibaran LIP (Figure 33), (Tack et al, 2008).…”

“…In the Lake Victoria region, there is a 100 km wide semi-circular mafic dyke swarm which is hosted within the Paleoproterozoic Rwenzori Fold Belt (RFB), and that circumscribes coeval maficultramafic and granitic intrusions hosted in the KAB (Figure 34a, Mäkitie et al, 2014). Arcuate lineaments were first recognized by Baterham et al (1983) and Chavez Gomez (2000); however it was not until recently that the full extent of the swarm became apparent from extensive aeromagnetic surveys.…”

“…There are three leading proposals in which the LVDS and coeval intrusions could be linked with a mantle plume, which are summarized in full in Mäkitie et al (2014). In short, these are: 1) a plume centre at Lake Victoria, with the LVDS representing two failed rift arms, while a third minor branch may be hidden beneath Lake Victoria (Figure 46a), 2) a plume the northern end of the LVDS (Figure 46b), and 3) a plume located at the centre of the LVDS (Figure 46c).…”

“…6.3 Kunene-Kibaran LIP (c. 1380 Ma), East Africa 6.3.1 Geology of the Lake Victoria Region The c. 1380 Ma Kunene-Kibaran LIP(Figure 33)is a major magmatic event in central Africa related to the breakup of the Columbia/Nuna supercontinent (e.g Meert, 2012;Evans, 2013; . Pisarevksy et al 2014), with components distributed across the Greater Congo Craton (GCC)Tack et al, 2010;Mäkitie et al, 2014). Fragments of the LIP are currently recognized in three regions of the GCC(Figure 33): 1) the mafic-ultramafic intrusions of the Kabanga-Musongati lineament, and associated gabbro-norite sills and S-type granites hosted within the Karagwe-Ankole Belt (KAB) in the northeast GCC, 2) the mafic-intermediate Kibara Belt (KIB) in the southeast GCC, and 3) the Kunene layered complex with its associated granites and dykes in the southwest GCC.…”