Browsing by Author "Getahun, Abera"

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    The Geology and Geochemistry of the Banded Iron Formation in Chago-werekalu, Wellega Province
    (Addis Ababa University, 1985-10) Getahun, Abera; Valera, Roberto (Prof.)
    The r ocks of the stulied area form nart of the ~ o llepa Birbir proup of the uppe r c08plex and consist of a series of me t ased i me ntary and plutonic proterozoic rocks. The winiera lo~ical assembl age indicate tha t t he metamorphism is of the r r eenshist facies. The variation diagram cons tructed for the va rious plut onic re e ks stronpl y supvest coma pmatic oripin by crysta l f rac ti ona ti on . Major and trace element ana lyses of re ore sentative samples of the Chago iron formation ? t he plutonic ann. YOllnp:er e f f us i ve rocks are presented . The Chago iron f ormation can be c las s i f i ed as nre cambrian banded iron for mation and is in J11any r espects siJrii l ar to the oxide fa cies iron format i on of Lake Superior t ype. The Cha go iron fo r mation consis t s only of Iron oxides and mi nor amoun t of sil i ca with total absence of iron silica t e, s ulfide and carbonate minerals. Trace element pe ochemis try sUPRests that t he iron f orma ti on was chemic ally prec i pitated as ox ida t e s ediments in which the principal i ron mineral, ma gne tite 1 was formed at low te mpera ture in a s ~lallow nea r shore environment .