Writers : Monazami Bagherzade, R.; Mirnejad, H.; Ashbak, P.
Refference : 1st Symposium of Iranian Society of Economic Geology
Publishing Year : 1389

Abstract :

The spreading of listwaenite is worthy of in some of the points of world and in east coloured mélange complex especially in Iran, the spearding listwaenite show off with high concentration. In the coloured mélange complex, the spreading of listwaenitic outcrops is observed in the Hangaran area located in the south of Mokhtaran. On the whole, listwaenites in the study area can divide to main three class with a view to petrology: 1)carbonatic,
2)carbonatic-silicic, 3)breccias silicic + sulfide minerals ± Fe- oxide – hydroxides. The amount of gold in listwaenite rocks is low, and the most its show in breccias silicic + sulfide minerals ± Fe-oxide – hydroxides type. Gold in listwaenite is small grain and its maximum size become 80 micron and mostly accompanied to pyrite.
The results of point analysis data (electron microprobe) show that mostly sulfides in the Hangaran listwaenites are formed from pyrite, marcasite, bravoite and chalcopyrite, and main of pyrite has returned to marcasite. The majority of carbonate are dolomite and magnesite, and the formed oldest minerals at the carbonatic and carbonatic-silicic listwaenites in the area is carbonates (majority dolomite and magnesite) and sulfides (mainly pyrite). Quartz has mainly shown as silicic veinlets and secondary minerals result of alteration of carbonates and sulfides that they have accounted as party (latest) of delay phases.Existence of the index mineral of bravoite with evident zoning has formed because of the nickel alternate varies so that in the Hangaran listwaenites is showing of alternation physico-chemical varies in the thermal fluid. Study of stable isotopes (Carbon and oxygen) in listwaenites show that primitive carbonates have deep oceanic origin which have placed on continent surface after area tectonism. These carbonates have affected by hydrothermal fluids and finally have substitude in serpentine and listwaenites. On the basis of, witnesses of sulfur isotope study on sulfide minerals in the
listwaenites such appear as that young intrusive rocks in this area are setting of precious and base metals for example Au,Ag,Cu,Hg,As. Then, we can generally statement that the source of Au is granite rocks in the south of study area, and the main of gold has transported by H2Scomplex at the reduce environment in thermal fluid. The study΄s results of fluid inclusion in the Hangaran listwaenites show that the environment of effective thermal fluid on the host rock have been mainly alkaline to low salinity and with varity Ph, and it has shown that temperature of fluid was maximum 140°c.

Subject List : Listwaenite