DUNITE BLOCKS IN MAFIC-ULTRAMAFIC SEQUENCE: EVIDENCE FOR MAGMA CHAMBER

The study area is located Eastern Taurus Belt. The ophiolitic units is one of remnant of oceanic lithosphere in Neotethyan ocean.

Mafic-Ultramafic section in the Guleman ophiolite are consist of dunite containing disseminated chromites, wehrlite, gabbros (layered gabbro and layered gabbro) and clinopyroxenite. Dunite blocks above the harzburgite massif are very interesting. These blocks have irregular contacts with the enclosing peridotites. Dunite blocks are generally around a few of meters. Dunite blocks consists of gabbro and pyroxenite patches.

The origin of dunite blocks which are belong to the transition zone of harzburgitic ophiolites is located at the base of the mafic layered section. Their are entirely or largely magmatic formed by olivine and chromite ponds at the base of the crustal magma chamber.

Magmatic origin of these dunite blocks is supported by geochemical evidence. One of this evidence Ni value are 3131 ppm in harzburgites and 2027-2036 ppm in dunites and others evidence forsterite (Fo) value of olivine in dunites is coommonly equal to harzburgites. This results are shown in values that dunites represents from harzburgite not produced by interaction with a melt otherwise dunite represents a higher fo contents harzburgites.

These geological, geochemical and petrological characteristic suggest that these dunite block are considered to be the the product of melt-peridotite interaction and is produced blocks fault above small magma chamber.

⁴⁰Ar-³⁹Ar isotope age in plagioclase within gabbros of the Guleman ophiolite are determined as a 72.4 million age. This is equal to Santonien.