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Geochemistry and Geochronology of the Bimodal Volcanic Rocks of the Suguti Area in the Southern Part of the Musoma-Mara Greenstone Belt, Northern Tanzania

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dc.creator Mtoro, Mwache
dc.creator Maboko, Makenya A. H.
dc.creator Manya, Shukrani
dc.date 2016-03-02T09:45:14Z
dc.date 2016-03-02T09:45:14Z
dc.date 2009-11-30
dc.date.accessioned 2018-04-18T11:49:53Z
dc.date.available 2018-04-18T11:49:53Z
dc.identifier Mtoro, M., Maboko, M.A. and Manya, S., 2009. Geochemistry and geochronology of the bimodal volcanic rocks of the Suguti area in the southern part of the Musoma-Mara Greenstone Belt, Northern Tanzania. Precambrian Research, 174(3), pp.241-257.
dc.identifier 10.1016/j.precamres.2009.07.006
dc.identifier http://hdl.handle.net/123456789/551
dc.identifier.uri http://hdl.handle.net/123456789/10250
dc.description The Suguti volcanic rocks of the southern Musoma-Mara greenstone belt in northern Tanzania comprise mainly of a bimodal suite of tholeiitic basalts-basaltic andesites and calc-alkaline rhyolites with a subordinate amount of intermediate rocks. Zircon U–Pb and whole rock Sm–Nd geochronology suggests that the two suites are cogenetic and were emplaced at 2755 ± 1 Ma with a common initial ɛNd value of 2.1. The tholeiitic basalts are characterised by relatively flat chondrite-normalised REE patterns with La/YbCN ratios of 0.8–1.6 (mean = 1.0). The basalts also exhibit negative Ti and Nb anomalies in primitive mantle-normalised multi-element diagrams. The flat REE patterns, the presence of prominent negative Nb anomalies and the positive initial ɛNd value of 2.1 suggest that the basalts were formed by low pressure melting of a mantle wedge in an active continental margin setting. Compared to the tholeiitic basalts, the calc-alkaline rhyolites are characterised by low abundances of the transition elements (Cr < 20 ppm, Ni < 20 ppm) and moderately high HFSE (e.g. Zr = 111–250 ppm) abundances. The rhyolites display strongly fractionated, slightly concave upward chondrite normalised REE patterns that are characterised by a slight depletion of the MREE relative to the HREE and minor to large negative Eu anomalies (Eu/Eu* = 0.3–0.9) and their epsilon Nd values range from +2.05 to +2.33. The depletion of the MREE relative to the HREE is an indication of fractionation of clinopyroxene and hornblende during petrogenesis whereas the negative Eu anomalies indicate plagioclase fractionation. The rhyolites are interpreted to have formed from the parental magma of the basalts by fractional crystallization and/or partial melting of a relatively young basaltic crust.
dc.language en
dc.publisher Elsevier
dc.subject Musoma-Mara greenstone belt
dc.subject Geochemistry
dc.subject Sm–Nd isotope
dc.subject U–Pb zircon geochronology
dc.title Geochemistry and Geochronology of the Bimodal Volcanic Rocks of the Suguti Area in the Southern Part of the Musoma-Mara Greenstone Belt, Northern Tanzania
dc.type Journal Article


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