Whole Rock and Mineral Chemistry of Ultramafic-mafic Cumulates from the Orhaneli (Bursa) Ophiolite, NW Anatolia

Authors : ENDER SARIFAKIOĞLU, HAYRETTİN ÖZEN & JOHN A. WINCHESTER

Pages : 55-83

View : 15 | Download : 4

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The Orhaneli ophiolite, situated in the western part of the İzmir-Ankara-Erzincan Suture Zone insert ignore into journalissuearticles values(İAESZ); and south of Bursa, exposes cumulates belonging to the mantle-crust transition zone. The Orhaneli ophiolite consists mainly of ultramafic cumulates and subordinate mafic cumulates. The basal cumulate sequence comprises dunites locally interlayered with chromitite levels. Above, dunitic cumulates, commonly interbanded with cumulate wehrlites, grade up into two pyroxene peridotites insert ignore into journalissuearticles values(cumulate lherzolites showing some transition to cumulate harzburgites in places);. The observation of cumulate gabbroic thin layers intercalated with ultramafic cumulates at least three times suggests that the magma chamber was periodically replenished by basaltic liquids. Petrographic studies show that the crystallization orders in the mafic-ultramafic cumulates follow two lines: insert ignore into journalissuearticles values(1); sp-ol-cpx-plag insert ignore into journalissuearticles values(chromitite, dunite, wehrlite, pyroxenite, gabbro);, insert ignore into journalissuearticles values(2); sp-ol-cpx-opx-plag insert ignore into journalissuearticles values(chromitite, dunite, wehrlite, lherzolite, harzburgite, pyroxenite, gabbro);. Geochemical analysis has shown that Th enrichment within the LILE insert ignore into journalissuearticles values(K, Sr, Rb, Ba); group and the depletion of HFSE insert ignore into journalissuearticles values(Ti, Nb, Zr, Y); relative to MORB indicate a suprasubduction zone tectonic setting for the formation of the Orhaneli ophiolite. The cumulate gabbroic rocks show low Ti insert ignore into journalissuearticles values(
Keywords : Mantle crust transition zone, mafic ultramafic cumulates, magmatic recycling, magma chamber, crystallization order, SSZ type ophiolite, Turkey