QE391 : Mineralogy, Geochemistry and genesis of the Hafthar Zn-Pb ore deposit, south west of Aqda
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2018
Authors:
Vahid Koohjani Goji [Author], Fardin Mousivand[Supervisor], Abdorrahman Rajabi [Advisor]
Abstarct: The Hafthar Zinc-Lead ore deposit is located in the 32 km southwest of Aghda and 1.8 km west of Hafthar village in the sedimentary sequence of the lower- middle Cambrian occurred in central Iran. The host rock ore is black shale and sandstone. Mineralization in the host sequence has occurred in the form of mass, laminated and vein- veinlets. baxsed on the nature of primary mineralogy and mineral fabrication, it is possible to distinguish between three ore-bearing facies, which are baxsed on their location relative to the outlet of irrigation fluid from below-up are as follows: A) Vein- veinlets less ore facies located below the massive deposits of the ore and Include silicification and calcite veins with a small amount of chalcopyrite, galena, sphalerite and pyrite. In parts of this facies, barite crystals have also been observed. The vein-veinlets of this facies have interrupted the laxyering of the host rock and the shear effects of this facies are also observed. Disseminated mineralization is also seen. B) Vent- complex ore facies (massive ore) that forms the major part of the deposit and Includes massive sulfide mineralization and slope with sedimentation. The main feature of this facies is a large replacement of the host rock by pyrite, galena and sphalerite. The dominant minerals of this facies include first-generation pyrites, replaced by second generation galena and sphalerite. The dominant process in this facies is the reaction between ore forming fluid and first generation of pyrite and the result is the formation of vein-veinlets, massive and replacement and C) Bedded ore facies which has less thickness than massive ore facies And includes alternating laminates of siltstone of host rock and sulfide ore that is also consistent with the laxyering process and syndepositional (stratiform) is formed. Also sulfide deposition dispersed may form pyrite rich laminates (Py1) and organic materials, as well as pyrite (Py), galena (Gn) and sphalerite (Sph) rich in laminates (so that the composition of the host's rock is not recognizable). Pyrite is the main mineral of this facies. The main textures of this facies including laminated, disseminated and banded and the processes of mextamorphism and deformation have led to the folding of this facies. The main alteration associated with mineralization, silicification, carbonate, chlorite and minor sericitization. Geochemical studies in the Hafthar area indicate that the origin of the host rock of mineralization is the granodiorite and the tectonic environment forms the continental active margin. Ba, Ag, Cu and Sr elements in massive ore facies and Sb, As and Cd in bedded ore facies are enriched. In order to change from massive ore facies to the bedded ore facies of enrichment, the elements As, Cd, Zn and Sb are visible. Sulfur isotopic studies conducted over the sulfide minerals of galena and pyrite represents δ ^ 34 S ranges between 16/6 to 18/6 ‰. According to the available evidence, it can be attributed to the source of ore-contaminated sulfur to bacterial reduction of seawater sulfate (BSR). According to the basic characteristics of mineralization in the Hafhar ore deposit, including tectonic setting, host rock, ore facies, geometric shape of mineral, mineralogy, mextallic content, mextal zonation and mineralogy in ore deposit, geochemical and isotopic characteristics, alteration and comparison with basic properties with sulfur deposit reservoirs with sedimentary host, Hafthar deposit can be classified in the category of SEDEX Selwyn- type.
Keywords:
#Zinc- lead #Sulfur isotope #Lower- middle Cambrian #Hafthar #Yazd block #sedimentary- exhalative. Link
Keeping place: Central Library of Shahrood University
Visitor: