The study of alteration and Zn-Pb skarn mineralization in Namar deposit, Central Alborz

Category Economic geology & mineral exploration
Group GSI.IR
Location The 24 Symposium of Geosciences
Holding Date 15 August 2007

Abstract

Skarn type Zn-Pb mineralization in Namar deposit, Central Alborz, has occurred as vein form, karstic cavities filling and disseminated within Lar Formation impure limestones. Contact metamorphism has happened and the lower parts of area subsequent to emplacement of trachytic body in the low depths and advanced to garnet and pyroxene formation. With the beginning of magma crystallization and release of hydrothermal fluids, complex metasomatic reactions have occurred that its result, the presence of mineral assemblage such as zoned garnet, magnesiohornblende, Na-bearing amphibole (pargasite), orthoclase, epidote, actinolite, clinochlore and sphene. Alkali metasomatism alteration of trachytic body has occurred  contemporaneously with metasomatic processes and its result orthoclase formation in the exoskarn zone. Sericitic alteration of igneous body is contemporaneously with precipitation of ore minerals. Mineralization within the limestone and achieved in two oxidized and reduced stages. Oxidized stages distinguished with the presence of magnetite. With evolution of hydrothermal fluids and to rise of sulfur fugacity, sulfide minerals precipitation in turn. Geochemichal evidence like the absence of Ce anomaly, presence of positive Eu anomaly and high (La/Yb)cn ratios in the skarn samples explain the role of magmatic hydrothermal fluids in the skarn formation

tags: QAZVIN