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The geochemistry and isotopic composition of the mafic and intermediate igneous components of the Cape Granite Suite, South Africa

dc.contributor.authorJordaan L.J.
dc.contributor.authorScheepers R.
dc.contributor.authorBarton E.S.
dc.date.accessioned2011-05-15T15:59:21Z
dc.date.available2011-05-15T15:59:21Z
dc.date.issued1995
dc.identifier.citationJournal of African Earth Sciences
dc.identifier.citation21
dc.identifier.citation1
dc.identifier.issn8995362
dc.identifier.urihttp://hdl.handle.net/10019.1/11131
dc.description.abstractA number of small outcrops of igneous rocks, gabbroic to granodioritic in composition, occur scattered throughout the western Cape in South Africa. These outcrops, which are mostly intrusive into the Malmesbury metasedimentary sequence, define a small number of medium-sized plutons. A characteristic feature of the larger plutons is their composite nature. Each pluton consists of multiple intrusive phases; a few show extensive hydrothermal alteration. Plutons from Yzerfontein and Mud River, which occur in the Tygerberg terrane, are high-K calcalkaline (K-trans-alkaline) while all plutons from Malmesbury, which occurs in the Swartland terrane, are tholeiitic. The high-K suite correspond to other I-type Cape granites, whereas the tholeiitic Malmesbury plutons may be a precursor of A-type Cape granites in both the Tygerberg and Swartland terranes. Monzonite from the Yzerfontein pluton yielded a UPb age of 519±7 Ma on zircon mineral separates. Rb-Sr isotope data did not yield reliable ages, possibly due to alteration, but yielded distinct initial isotope ratios for the high-K calc-alkaline and the tholeiitic plutons. The δ34S isotope ratios of pyrite range from 1 to 2.7% for Yzerfontein and from 3.6 to 4.6% for Mud River, suggesting a magmatic source for the pyrite. PbPb data on whole rock and pyrite samples imply crustal input into all the original magmas. © 1995.
dc.subjectCape Granite Suite
dc.subjectgranite
dc.subjectigneous geochemistry
dc.subjectintermediate rock
dc.subjectisotopic analysis
dc.subjectmafic rock
dc.subjectSouth Africa, Cape Province
dc.titleThe geochemistry and isotopic composition of the mafic and intermediate igneous components of the Cape Granite Suite, South Africa
dc.typeArticle
dc.description.versionArticle


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