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FORMATION OF ERENKOY MAGNESITE DEPOSITS, ESKISEHIR, WESTERN TURKEY: AN INITIAL STUDY

AUTHOR/S: T. A. KEPEKLI, M. MARAL, F. SUNER
Sunday 1 August 2010 by Libadmin2010

10th International Multidisciplinary Scientific GeoConference - SGEM2010, www.sgem.org, SGEM2010 Conference Proceedings/ ISBN 10: 954-91818-1-2, June 20-26, 2010, Vol. 1, 445-450 pp

ABSTRACT

Erenkoy magnesite deposits reside in Eskisehir and Bilecik provinces of northwestern
Turkey. Local geology consists of metamorphites of blueschist facies in the base;
ophiolitic rocks with mainly serpentinites, peridotites; ophiolitic melanges with a
varying range of lithology: cherts, calcschists, blueschist rocks, limestone and on top of
all these there are neogene sedimentary units that are mainly consisted of sandstone and
clay formations. Magnesite deposits in the area are associated with ultramafic rocks:
serpentinites and peridotites. The deposits are shaped as veins and veinlettes,
stockworks and lenses primarily however most of them have lost their primary shape
due to intense tectonic activity and resulting deformation, therefore sometimes showing
irregular masses. The formations of magnesite usually strictly follow discontinuities like
fault and crack zones. The magnesites are white colored, cryptocrystalline and mostly
have either massive habit, showing conchoidal fractures and dehydration cracks or
botryoidal (cauliflower) habit. They show microscopic pinolite textures. Magnesites in
the deposits are usually accompanied with dolomites, sepiolites, serpentines, talc,
quartz, opal, chalcedony (formed in vugs), iron oxides. Magnesite is also present along
with serpentintes, iron oxides, dolomites and silica formations on the surface in
extensive weathered and altered parts of the host rocks. Initial geochemical analyses
show high SiO2 content in magnesites, Fe2O3 content is also elevated in some samples
taken from surface. These indicate to silica and iron oxide formations associated with
magnesite deposits. Also elevated CaO content in some samples can be explained by
dolomite formations in Magnesite deposits.

Keywords: Magnesite, Carbonates, Weathering, Alteration, Ophiolites