The non-sulfide ore Formation conditions of Ravar-Bafgha rea, findings of carbon and oxygen stable isotopes

Document Type: Original Article

Authors

1 Department of Geology, Faculty of Basic Science, Islamic Azad University - Zarand Branch, Zarand, Iran

2 Department of Geology, Faculty of Earth Science, Shahid Beheshti University, Tehran, Iran

Abstract

The carbonate-hosted zinc-lead deposits of Ravar-Bafgh area mainly contain non-sulfide ore. In this article, we have studied the variations of carbon and oxygen isotopic ratios from separated non-sulfide minerals. The range of δ13CPDB in the smithsonite varies from -1.456 to -7.248‰ and shows a good congruency with meteoric CO2. In the hemimorphite, 13CPDB values vary from -17.871 to -23.554‰ and show high enrichment of light carbon isotope. Vein-type aragonite associated with non-sulfide ore is formed under the same conditions as the smithsonite, but the calcite mineral associated with sulfide ore is formed under the same conditions as the limestone. The range of 18OSMOW and 18OPDB isotopic ratios is studied in the mentioned minerals. In the smithsonite, the δ18OSMOW values vary from +21.821 to +26.445‰, the values of δ18OPDB vary from -6.882 to -8.768‰, the values in the hemimorphite vary from +16.263 to +19.580‰ and from -10.876 to -14.160‰ for 18OSMOWand 18OPDB respectively. These values show that the non-sulfide minerals of these deposits are formed during the weathering of exposed sulfide ore and the fluids responsible for these processes are descending meteoric waters with minor amount of pore waters entrapped in the porosity of the carbonate host rocks.

Keywords