Research Information System
JOURNAL OF ASIAN EARTH SCIENCES, vol.185, 2019 (SCI-Expanded)
The Akcaabat gold deposit is mainly composed of massive arsenopyrite veins in strongly foliated augen gneisses of the tine Sub-massif in western Turkey. K-bearing minerals from orogenic gold veins were dated by the in situ Rb-Sr method in order to determine the formation age of the Akcaabat gold deposit. Textural relationships between the vein minerals suggest that arsenopyrite, K-feldspar, quartz, and muscovite formed in one paragenetic stage. Native gold, native bismuth, scorodite, and galena were introduced in a later paragenetic stage. The isochron derived from K-feldspar and muscovite occurring in the veins yielded 31.3 +/- 4.7 Ma. In situ Rb-Sr dating of the same assemblage (K-feldspar and muscovite) in the host rock gave an isochron age of 40.8 +/- 3.8 Ma, 10 Ma older than the vein ages, and corresponding to peak metamorphism of the regional main Menderes metamorphism during the Alpine-Himalayan orogenic event. Biotite from the host rock gave an isochron age of 28.1 +/- 2.2 Ma and probably reflects the cooling age. Homogenization temperatures from fluid inclusions in quartz show that quartz formed at 280-390 degrees C but has a dominant mode in the 350-360 degrees C temperature interval. The age of vein formation was successfully distinguished from the age of the Alpine-Himalayan orogenic event associated with main Menderes metamorphism. This study demonstrates that in situ Rb-Sr isotopic study can be applied to resolve absolute dating of orogenic deposits in metamorphic complexes.