Document Type : Original Research Paper

Author

Assistant Professor, Department of Geology, Payame Noor University, Iran

Abstract

In the studied area, the Cretaceous limestone rocks with abundant cracks are located on the Jurassic shales. Skarn producer fluids have influx into these cracks from a long distance and created distal skarns. The presence of a recrystallized and skarnified limestone rock layer within the shale, distinct the studied skarn from the most well-known skarns in Iran and puts it in the category of reaction skarns. There are some lenses of mineral deposites within skarns which is consisting mostly of magnetite and hematite. Iron-rich solutions which are drived from intrusive rocks, have left iron as magnetite in carbonate. In addition to the formation of magnetite by hydrothermal solutions, it can also be created in retrograde step by andradite alteration. These skarn is consisting mostly of pyroxene, garnet, tremolite-actinolite, chlorite and epidote. Skarnification process has occurred in two successive stages: progressive and regressive. In progressive stage, carbonate - silicate anhydrous minerals like garnet and pyroxene have occured. At later stages, because of the atmospheric water influence, garnets are altered to epidote, magnetite, calcite and quartz and pyroxenes are altered to tremolite, actinolite, calcite, quartz and opaque minerals. There are two set of garnet in studied skarn, the first one is massive (in progressive stage) and the other one is as veinlet (in regressive stage with epidote and has been created in quartz- calcit veins along with sulfide mineralization). Garnet compositions in iron deposits of studied area lie in grossular - andradite series. The compositions of studied garnet are the same as garnet compositions in Cu-Fe skarns in worldwide.
 

Keywords

References
Barker, A. J., 1990- Metamorphic texture and microstructures. Blackie and Sons, Glasgow, London 289pp.
Barnes, H. L., 1997- Geochemistry of hydrothermal ore deposits. John Wiley and sons, New York 780pp.
Barton, M. D. and Johnson, D. A., 1996- An evaporitic-source model for igneous- related Fe- oxide (REE- Cu- Au- U) mineralization. Geology 24(3): 259−262.
Barton, M. D. and Johnson, D. A., 2000- Alternative brine sources for Fe- oxide (-Cu-Au) systems: Implications for hydrothermal alteration and metals. In: T. M. Porter (Editor), Hydrothermal Iron Oxide Copper-gold and Related Deposits: A Global Perspective. Australian Mineral Foundation Inc, Adelaide, 43−60.
Cepedal, A., Martın-Izard, A., Reguilón, R., Rodrıguez-Pevida, L., Spiering, E. and González- Nistal, S., 2000- Origin and evolution of the calcic and magnesian skarns hosting the El Valle-Boinás copper–gold deposit, Asturias (Spain). Journal of Geochemical Exploration 71 (2): 119–151.
Ciobanu, C. L. and Cook, N. J., 2004- Skarn textures and a case study: The Ocna de Fier-Dognecea orefield, Banat, Romania. Ore Geology Review 24 (3): 315–370.
Deer, W. A., Howie, R. A. and Zussman, J., 1996- An introduction to the rock forming minerals. Scientific and Technical. Longmans, London 549 pp.
Dupuis, C. and Beaudoin, G., 2011- Discriminant diagrams for iron oxide trace element fingerprinting of mineral deposit types. Mineralium Deposita 46: 319-335.
Einaudi, M. T., Meinert, L. D. and Newberry, R.J., 1981- Skarn deposits. Economic Geology 75th anniversary volume: 317-391.
Einaudi, M. T. and Burt, D. M., 1982- Introduction-terminology, classification and composition of skarn deposits. Economic Geology 77:745–754.
Einaudi, M. T., 1982- Introduction, terminology, classification and composition of skarn deposits. Economic Geology 22:120- 251.
Einaudi, M. T., Meinert, L. D. and Newberry, R. J., 1981- Skarn deposits. Economic Geology, 75th Anniversary Volume 317–391.
Grammatikopoulos, T. A. and Clark, A. H., 2006- A comparative study of wollastonite skarn genesis in the Central Metasedimentary Belt, southeastern Ontario, Canada. Ore Geology Review 29 (2): 146–161.
Guilbert, J. M. and Park, C. F., 1986- The Geology of Ore Deposits. W.H. Freeman and Co., Oxford and New York 985 pp.
Hall, D. L., Cohen, L. H. and Schiffman, P., 1988- Hydrothermal alteration associated with the Iron Hat iron skarn deposit, easternMojave Desert, San Bernardino County, California. Economic Geology 83: 568–587.
Hyndman, D. W., 1985- Petrology of Igneous and metamorphic rocks, 2nd Ed., Mc Graw Hill, New York 786 pp.
Jamtveit, B., Wogelius, R. A. and Fraser, D. G., 1993- Zonation patterns of skarn garnets, records of hydrothermal system evolution. Geology 21: 113 - 116.
Kamvong, T. and Zaw, Kh., 2009- The origin and evolution of skarn-forming fluids from the Phu Lon deposit, northern Loei Fold Belt, Thailand: Evidence from fluid inclusion and sulfur isotope studies. Journal of Asian Earth Sciences 34: 624-633.
Karimzadeh Somarin, A., 2004- Garnet composition as an indicator of Cu mineralization Evidence from skarn deposits of NW Iran. Journal of Geochemical Exploration 81: 47- 57.
Karimzadeh Somarine, A., 2010- Garnetization as a ground preparation process for copper mineralization: evidence from the Mazraeh skarn deposit, Iran. International Journal of Earth Sciences (Geol Rundsch) 99: 343-356.
Kretz, R., 1994- Metamorphic crystalization. John Wiley and Son, New York 507pp.
Lehrmann, B., Oliver, N. H., Rubenach, M. J. and Georgees, C., 2009- The association between skarn mineralisation and granite bodies in the Chillagoe region, North Queensland, Australia. Journal of Geochemical Exploration101 (1): 58.
Lingang, X., Mao, J., Yang, F., Daniel, H. and Zheng, J., 2010- Geology, geochemistry and age constraints on the Mengku skarn iron deposit in Xinjiang Altai, NW China. Journal of Asian Earth Sciences 39:423–440.
Marschik, R. and Spikings, R., 2008- Geochronology and stable isotope signature of alteration related to hydrothermal magnetite ores in Central Anatolia, Turkey. Mineralium Deposita 43(1): 111−124.
Meinert, L. D., 1992a- Skarns and skarn deposits. Geoscience Canada 19: 145 - 162.
Meinert, L. D., 1992b- Skarn zonation and fluid evolution in the Groundhog Mine, Central Mining District, New Mexico. Economic Geology 82: 523–545.
Meinert, L. D., 1995- Compositional variation of igneous rocks associated with skarn deposits—chemical evidence for a genetic connection between petrogenesis and mineralization. Mineralogical Association of Canada, Short Course Series 23: 401–418.
Meinert, L., Dipple, G. and Nicolescu, S., 2005- World skarn deposits, in Hedenquist, J.W., et al., eds., Economic Geology 100th Anniversary Volume: Littleton, Colorado, Society of Economic Geologists, 299–336.
Mucke, A. and Cabral, A. R., 2005- Redox and nonredox reactions of magnetite and hematite in Rocks. Chemie der Erde 65:271- 278.
Murray, J. W., 1979- Iron oxides. In: Burns, R.G. (Eds.), Reviews in Mineralogy 6, Marine Minerals. Mineralogical Society of America, Washington DC: 47−98.
Nadoll, P., Angerer, T., Mauk, J. L., French, D. and Walshe, J., 2014- The Chemistry of hydrothermal magnetite: A review. Ore Geology Reviews 61:1-32.
Nakano, T., 1989- Fluctuation model for compositional heterogeneity in skarn clinopyroxenes. Geochemical Journal 23(3): 91-99.
Niiranen, T., Manttari, I., Poutiainen, M., Nicholas, H. S. and Jodie, A., 2005- Genesis of Palaeoproterozoic iron skarns in the Misi region, northern Finland. Mineralium Deposita 40: 192-217.
Purtov, V.K., Kholodnoc, V. V., Anfilogov, V. N. and Nechkin, G. S., 1989- The role of chlorine in the formation of magnetite skarn. International Geology Review 31: 63–71.
Ray, G. E. and Lefebure, D. V., 2000- A synopsis of iron oxide ± Cu ± Au ± P ± REE deposits of the Candelaria-Kiruna-Olympic Dam family. Geological fieldwork 1999, Paper No. 2000– 1, British Columbia Geological Survey 267–272.
Shimazaki, H., 1980- Characteristics of skarn deposits and related acid magmatism in Japan. Economic Geology 75: 173–183.
Sun, S. S. and McDonough, W. F., 1989- Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geological Society, London, Special Publications 42:313-345
Vallance, J., Fontboté, L., Chiaradia, M., Markowski, A., Schmidt, S. and Vennemann, T., 2009- Magmatic-dominated fluid evolution in the Jurassic Nambija gold skarn deposits (southeastern Ecuador). Mineralium Deposita 44: 389-413.
Xu, G. and Li, X., 2000- Geology and geochemistry of the Changlongshan skarn iron deposit, Anhui Province, China. Ore Geology Review 16:91–106.
Zharikov, V. A., 1991- Skarn type, formation and mineralization condition in skarns- their genesis and metallogeny (A. Bartokyriakidis, ed.). Theophrastus publishing and proprietary Co., S. A., Atheen, Greece 455-466.