GEOCHEMISTRY INTERNATIONAL, vol.48, no.10, pp.1014-1027, 2010 (SCI-Expanded)
The study area comprises Cayirli, HarapaC illari and Ortabel (CHO) districts in the Haymana town 25 km SW of the Ankara city. In this study, geologic setting, mineralogical and geochemical characteristics of manganese mineralizations are examined and their origin is discussed. Data were obtained from field observations, various polished and thin section determinations and chemical analyses of 25 ore samples. Major and trace element analyses were conducted with ICP-ES and ICP-MS methods at ACME Laboratories (Canada). CHO manganese ores are found in reddish radiolarites and partly interbedded marls of the Ankara ophiolitic melange of lower Cretaceous-upper Senonian age. In these extremely folded rocks, manganese is observed as band and lenses. All samples are composed of pyrolusite and quartz. Circular pyrolusites around the gangue form a ring texture and radiolarite ores yield spherical sections. In addition, breccia-like texture is observed between pyrolusite and quartz. Geologic setting, mineralogical and textural data indicate an exogene environment. Major and trace element abundances and correlation among them imply that CHO mineralizations are of hydrothermal origin and linked to the same source. Evaluation of all these data shows that CHO manganese mineralizations are of hydrothermal type sedimentary mineralization and they were deposited in distal part of the source.