the Muratdagi Melange in this area. The Muratdagi Melange consists of mafic and ultramafic rocks, metadetrital rocks, recrystallized limestones and marbles.
MINERALIUM DEPOSITA
Mineral Deposit Letters
9 Springer-Verlag 1994 Mineral. Deposita 29, 361-365 (1994)
Stable isotope study of antimony deposits in the Muratdagi region, western Turkey A. Gok~e 1 and B. Spiro z Department of Geological Engineering, Cumhurriyet University, Sivas, Turkey 2 N E R C Isotope Geosciences Laboratory, Keyworth, Nottingham NG12 5GG, U K Received: 23 January 1992/Accepted: 8 December 1993
Abstract. The Muratdagi region is rich in antimony deposits having the following common characteristics: post Miocene age, location on the down-thrown blocks next to normal faults, in the vicinity of active or fossil thermal springs, and in contact with carbonate rocks. The isotopic composition of - 7%o. S M O W of the mineralizing fluid calculated from the measured 6 t s o of quartz and the fluid inclusion microthermometry, is indicative of meteoric water origin. The 613C of the inclusion CO 2 of - 19.1 to - 25.4%0 PDB is indicative of interaction with organic material-graphite. The 634S of stibnite - 3.6 to - 0.7%0 is, in view of the mineral assemblage, indicative of magmatic origin of the sulphur. A tightly confined set of structural, lithological, hydrological and geochemical features define a sequence of geochemical processes; formation of acid and reducing fluid, leaching and transport of antimony complexes and precipitation of stibnite within defined lithological units. The set of processes seems to have taken place within a space of 5000 m lateral and 1000 m vertical extension.
The Muratdagi Region is one of the important antimony producing areas in Western Turkey (Fig. 1). More than 10 antimony deposits have been mined periodically and two of them, Cebrail and Surtmece, are still being mined. A comprehensive investigation of the antimony mineralization phenomena in the area was carried out by the senior author (Gok~e 1986, 1987) using field, microscopic and geochemical methods including a literature summary of previous economical, and mineralogical investigations dating back as far as 1856. On this basis Gokqe (1987) suggested that the deposits were formed by hydrothermal solutions ascending along faults to zones very close to the present day topographic surface. Precipitation of their antimony, silica and carbonate content took place at the contact with carbonate-bearing lithologies. The components of the ore minerals are assumed to be derived from the surrounding metadetrital and metavolcanic rocks through leaching by deep circulating fluids. The fluids are assumed to be of surficial rather than magmatic origin. A study of mineralization in the northern part of the Muratdagi region, including fluid inclusions is reported by Aral (1989). The present study concentrates on the isotopic composition of sulphur in the stibnite crystals from several deposits in the region and the oxygen isotope composition of quartz from Surtmece where suitable material was found. This study attempts to clarify the geochemical relationship between the deposits and in particular identify the source of sulphur and its geochemical pathway.
Geological features The main regional geological features, namely, lithological units, structural features and location of mineralization phenomena are shown in the geological map (Fig. 1) (after Gokqe, 1987). The nomenclature of the lithological units were mostly taken from Bingol (1977).
Stratigraphy The oldest unit reported in the area is the Asagibelova Formation of Middle-Upper Jurassic age. It consists of metadetrital rocks (Yargediktepe Metamorphics) and dolomitic limestones (Ciceklikaya Member). The metadetrital rocks of the unit consist primarily of metasiltstones and metasandstones with quartz and sericite as major components with small amounts of albite, chlorite, epidote and calcite and some graphite in discerete horizons. The metamorphic mineral assemblage is indicative of low grade as defined by Winkler (1974). Bingol (1977) suggested an Upper Jurassic-Lower Cretaceous age of deformation and an age of metamorphism of 126.5 ___ 11 Ma based on Rb/Sr data. The Asagibelova Formation is overthrusted by the Muratdagi Melange in this area. The Muratdagi Melange consists of mafic and ultramafic rocks, metadetrital rocks, recrystallized limestones and marbles. The mafic and ultramafic part of the unit contains extensively serpentinized and mylonitized Iherzolite-harzburgite, gabbro, spilitic basalt, diabase and basic tufts, some metamorphic minerals such as chlorite epidote, glaucophane and cordierite are seen in some mylonitized areas in addition to the serpentine minerals. Metadetrital rocks of the unit contain quartz and muscovite (partly sericitic) and small amounts of chlorite staurolite and biotite with graphitic horizons. These metadetrital rocks were metamorphosed under the conditions of the lower temperature division of medium grade metamorphism defined by Winkler (1974). The metadetrital rocks of the Muratdagi Melange must have been metamorphosed under different conditions and in a different locality than the Yargediktepe Metamorphics. A Rb/Sr radiometric age of 70.4 + 3.0 Ma was interpreted as the age of tectonic emplacement of the melange into the area (Bingol 1977) The recrystallized limestones and marbles occur as separate blocks of different sizes and dispersed among the other components of the melange. The Baklan Granite with Rb/Sr age of 52 + 7 Ma (Paleocene) (Bingol 1977) was intruded into both the Asagibelova Formation and the Muratdagi Melange and thermally affected them. It is predominantly of biotite-hornblende granite composition. The Gokler sediments of Miocene age overly discordantly the Muratdagi Melange. They consist of conglomerate at the base, overlain by sandstones and siltstones and contain lignite beds.
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