Document Type : Research Paper
Author
Abstract
The Anarg Polymetallic skarn deposit ( Cu, Zn, Fe, Ag, Au) is located on the15 km west of the Posht-e- Badam village in the northeastern part of the Yazd province in central part of Iran. This area is situated in geological domain of the central Iran within the Anarak - Sarcheshmeh - Kharestan copper belt]. The Anarg's granitoid intruded within the center of north - south trending zone . The K/Ar radioisotope age of this granitoid body is middle Eocene, respectively. Lithologically of this granitoid body is composed of I- type granite, granodiorite, quartzmonzonite and less of tonalite and quartzdiorite. There is one calcic type skarn around this intrusion. The most
تاریخ دریافت مقاله: 6/12/1380 تاریخ پذیرش مقاله: 2/5/1381 email:skamalisadr@aeoi.org.ir *
important country rock is calcic marble, related to the Posht -e- Badam complex. The exoskarn mainly consists of garnet ( andradite- grossularite), clino - pyroxen (diopside - hedenbergite ), amphibole ( tremolite - actinolite), epidote, chlorite, calcite, quartz, magnetite, chalcopyrite, galena and sphalerite, where its high grade metamorphic facies is attained to the primer pyroxen - hornfels facies. The endoskarn minerals assemblage is composed of grassularite, andradite, epidote, chlorite, calcite, tremolite, actinolite, which its thickness is varied between 1-3 meters. The ore minerals occurred in three different localities (anomalies) namely A,B and C. The major part of economic ores are located within the exoskarn zone. This paragenesis not only is related to the composition of hosting, but also reflects the evolutionary processes of intrusion emplacement. The magmatic derived solutions resulted from fractional - crystalization of igneous melt, as well as their interaction with surrounding rock units participates to from the aforesaid polymetallic skarn - type deposit, by metasomatic processes. Skarnification in the Anarg ore field has been occurred in three stages namely:I) , Prograde, II). Retrograde - Metasomatic and III) Hydrothermal stages. The major ore mineralization has occurred during 2 nd stage. This deposit is a lenticular form body, accompanied by irregular massives and less amount of vein and veinlets. Their ores show massive, inclusion, disseminated and less amount replacement type textures. By considering the mineralogical peculiarities and their correlation with phase diagrams, it is concluded that the temprature of the mineral zone formations are as follows:
- Pyroxen zone , 450 -600 0C
- Garnet zone , 380 -480 0C
This skarn was formed by contact- infiltration of magmatic derived fluids. This processe has been intensified by fracturing systems of both magmatic and surrounding bodies. Mineralogical investigation ( X.R.D and ore microscopy) show that the major ore minerals are chalcophyrite, magnetite, galena and sphalerite. The Cu-content is varied between 0.35 to 12% , which indicates a remarkable deposit for mining consideration. It has to be mentioned that this deposit is classified as polymetallic - skarn type deposit, by considering the ( Cu, Zn, Fe, Ag, Au,) metals in ore fomation, which is related to the continental margin - type low angle subducted zone .
Highlights
- 1. A. Haghipour, “Etude geologigue de la region de Biabanak - Bafgh couverture,’’ These Univ. Grenoble, 403 (1974).
- D. E. Harnish and P. E. Brown,“Petrogenesis of the Casseus Cu-Fe skarn, Terre Heuve District,” Econ. Geol., 81:1801-1807 (1986).
- G. D. Layen, F. G. Longstaffe, and E. T. C. Spooner, “The Jc tin skarn deposit. Southern Yukon Territorty:II, A carbon, oxygen, hydrogen and sulfur stable isotope study,” Econ. Geol. 86, 48-65 (1991).
- 4. T. C. Labotka, “Chemical and physical properties of fluids in contact metamorphism,” Mineralogical Society of America, Rewiews in mineralogy, Bookcrafters Pub., 26, 43-104 (1991).
- 5. L. D. Meinert, “Skarn zonation and fluid evolution in the Groundhog mine , Central
Mining District,” New Mexico. Econ. Geol., 82, 523-545 (1987).
- 6. L. D. Meinert, “Igneous petrogensis and skarn deposits,” Geological Assiciation of Canada, Special paper, 40,569-583 (1995).
- 7. H. Mollai, “Petrochemistry and genesis of the granodiorite and associated iron-copper skarn deposit of Mazraeh, Ahar, Azerbaidjan, Iran,” Ph.D. thesis. Roorke. Univ., India (1993).
- D. Mullar, and D. I. Groves, “Potassic igneous and associated gold - copper mineralization,” Springer Pub., 241 (1997).
- 9. E. Romankov, Y. U. Kokorin, B. Krivyakin, M. Susov, L. Morozov, and M. Sharkovski. “Outline of metallogeny of Anarak area (Central Iran),” Geological Survey of Iran, Report Te/NO.21-1984 (1984).
- B. Samani, “Distribution setting and mettallogenic of copper deposits in Iran, A Global Perspective,” Australian Mineral Formation, 135-158 (1999).
- D. Shelley, “Igneous and metamorphic rocks under the microscope,” Chapman & Hall Pub., 298 (1993).
- T. E. Waight, S. D. Weaver, and R. J. Muir, “The Hohonu compositions controlled by source H2O contents and generated during tectonic transition,” Contrib. Mineral. Petrol. 128, 81-96 (1998).
- V. A. Zharikov, “Skarn types, formation and mineralization condition. In Skarn. their Genesis and Metallogeny,” ( A. Barto Kyriakidis. ed. Theophrastus publishing & proprietary Co., S. A., Athen . Greece., 455-466 (1991).
Keywords
- 1. A. Haghipour, “Etude geologigue de la region de Biabanak - Bafgh couverture,’’ These Univ. Grenoble, 403 (1974).
- D. E. Harnish and P. E. Brown,“Petrogenesis of the Casseus Cu-Fe skarn, Terre Heuve District,” Econ. Geol., 81:1801-1807 (1986).
- G. D. Layen, F. G. Longstaffe, and E. T. C. Spooner, “The Jc tin skarn deposit. Southern Yukon Territorty:II, A carbon, oxygen, hydrogen and sulfur stable isotope study,” Econ. Geol. 86, 48-65 (1991).
- 4. T. C. Labotka, “Chemical and physical properties of fluids in contact metamorphism,” Mineralogical Society of America, Rewiews in mineralogy, Bookcrafters Pub., 26, 43-104 (1991).
- 5. L. D. Meinert, “Skarn zonation and fluid evolution in the Groundhog mine , Central
Mining District,” New Mexico. Econ. Geol., 82, 523-545 (1987).
- 6. L. D. Meinert, “Igneous petrogensis and skarn deposits,” Geological Assiciation of Canada, Special paper, 40,569-583 (1995).
- 7. H. Mollai, “Petrochemistry and genesis of the granodiorite and associated iron-copper skarn deposit of Mazraeh, Ahar, Azerbaidjan, Iran,” Ph.D. thesis. Roorke. Univ., India (1993).
- D. Mullar, and D. I. Groves, “Potassic igneous and associated gold - copper mineralization,” Springer Pub., 241 (1997).
- 9. E. Romankov, Y. U. Kokorin, B. Krivyakin, M. Susov, L. Morozov, and M. Sharkovski. “Outline of metallogeny of Anarak area (Central Iran),” Geological Survey of Iran, Report Te/NO.21-1984 (1984).
- B. Samani, “Distribution setting and mettallogenic of copper deposits in Iran, A Global Perspective,” Australian Mineral Formation, 135-158 (1999).
- D. Shelley, “Igneous and metamorphic rocks under the microscope,” Chapman & Hall Pub., 298 (1993).
- T. E. Waight, S. D. Weaver, and R. J. Muir, “The Hohonu compositions controlled by source H2O contents and generated during tectonic transition,” Contrib. Mineral. Petrol. 128, 81-96 (1998).
- V. A. Zharikov, “Skarn types, formation and mineralization condition. In Skarn. their Genesis and Metallogeny,” ( A. Barto Kyriakidis. ed. Theophrastus publishing & proprietary Co., S. A., Athen . Greece., 455-466 (1991).
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