بررسی منشأ و شرایط شکل‌‌ گیری آگات‌ ها‌ی خور و بیابانک (استان اصفهان)

نوع مقاله : علمی- پژوهشی

نویسندگان

1 شهرکرد

2 اصفهان

چکیده

آگات‌های خور و بیابانک در حفرات گدازه‌های آتشفشانی ائوسن با ترکیب بازالت آندزیتی و در دل افق بنتونیتی خور شکل گرفته‌اند. مشاهدات صحرایی حاکی از فراوانی این ترکیبات سیلیسی در مجاورت درزه‌ها و گسلهاست. بر اساس آنالیز XRD ترکیبات پرکننده‌ حفرات در منطقه‌ مورد مطالعه علاوه بر آگات شامل عناصر کلسیت، دولومیت و باریت است. مقایسه‌ عناصر نادر و نادر خاکی در نمونه‌های سیلیسی با سنگ میزبان آندزیتی بیانگر روندی مشابه به همراه تهی‌شدگی شدید در نمونه‌های سیلیسی است. شواهد کانی‌شناسی حاکی از آن است که ژئودهای منطقه‌ طشتاب خور بر اثر خروج متناوب سیالات گرمابی در دمای پایین شکل گرفته‌اند. مطالعات ایزوتوپ‌های پایدار اکسیژن و دوتریوم نشان می‌دهد سیالات پدید‌ آورنده‌ این ترکیبات سیلیسی دارای منشأ جوی هستند.

کلیدواژه‌ها


Burkhard, M., 1993. Calcite twins, their geometry, appearance and review. Journal of Structural Geology, 15(3-5): 351-368.
Clayton, R.N., O’Neil, J.R. and Mayeda, T.K, 1972. Oxygen isotope exchange between quartz and water. Journal of Geophysical research, 77(17): 3057-3067.
Cox A.P. (translated by Moore, F. and Zaeri, K.), 2003. elements of earth. Shiraz university Publishing, Shiraz, 414 pp. (in Persian)
Deloule, E., Albarede, F. and Sheppard, S.M.F., 1991. Hydrogen isotope heterogenities in mantle from ion probe analysis of amphibole from ultra mafic rocks. Earth Planetary Science Letter, 105(4): 543-553
Duarte, L.C., Hartmann, L.A., Ronchi, L.H., Berner, Z., Theye, T. and Massonne, H.J., 2011. Stable isotope and mineralogical investigation of the genesis of amethyst geodes in the Los Catalanes gemological district, Uruguay, southernmost Parana volcanic province. Mineralium Deposita, 46(3): 239–255.
Florke, O.W., Kohler-Herberts, B., Langer, K. and Tonges, I., 1982. Water in microcrystalline quartz of volcanic origin: agates. Contribution to Mineralalogy Petrology, 80(4): 324–333.
Graham, C.M. and Harmon R.S., 1983. Stable isotope evidence on the nature of crust- mantle xenoliths: Shiva. Nantwich, UK: 20-45.
Gotze, J., Nasdala, L., Kleeberg, R. and Wenzel, M., 1998. Occurrence and distribution of Moganite in Agate/Calcedony: A combain Micro-roman, Rietveld, and cathodoluminescence study. Contribution to Mineralogy and Petrology, 133(1-2): 96-105.
Haj Alilou, B. and Vosough, B., 2009. Geological source of Mianeh agates. 17th Symposium of crystallography and mineralogy of Iran, Hamedan university, Hamedan. (in Persian with English abstract)
Haj Alilou, B., Vosough, B. and Moazen, M., 2011. Mineralogy, geochemistry, gemology and variety in colors of Mianeh agates. Iranian journal of crystallography and mineralogy of Iran, 19(3): 427-438. (in Persian with English abstract)
Hall, C., 2000. Gemstones. Droling Kindersley Publishing, London, 160 pp.
Hashemi, A., 2000. Khur tectonics. M.Sc. Thesis, Shahid Beheshty university, Tehran, Iran, 271 pp. (in Persian with English abstract)
Hopkinson, L., Roberts, S., Herrington, R. and Wilkinson, J., 1998. Self-organization of submarine hydrothermal siliceous deposits: Evidence from the TAG hydrothermal mound, 26°N Mid-Atlantic Ridge. Geology, 26(4): 347-350.
Juchem, P.L, Hartmann, L.A., Massonne H.J. and Theye T., 2009. Oxygen isotope composition of amethyst and related silica minerals in volcanic rocks from the Parana province, southern Brazil. XII Congresso Brasileiro de GeoquÃmica e VIII Internacional Symposium on Environmental Geochemistry, Ouro Preto. Geochimica Brasiliensis.
Kyser, T.K. and ONail J.R., 1984. Hydrogen isotope systematics of submarine basalts. Geochimica et Cosmochimica Acta, 48(10): 2123-2133.
Malek Mahmoudi, F., 2010. Mineralogical and geochemical studies of hydrothermal alteration and mineralization in Tashtab Mounts (NE of Isfahan province). M.Sc. thesis, Isfahan university, Isfahan, Iran, 109 pp. (in Persian with English abstract)
Malek Mahmoudi, F. and Khalili, M., 2011. The behavior of elements in the process of alteration of andesite - basalt to bentonite in Tashtab Mounts Khur, northestern Isfahan province. Journal of Economical Geology, 4(1): 1-26. (in Persian with English abstract)
Malek Mahmoudi, F. and Khalili, M., Mackizadeh, M.A., 2010. study of genesis and temperature of Khur agate formation. 17th Symposium of crystallography and mineralogy of Iran, , Bu Ali Sina university, Hamedan. (in Persian with English abstract)
Mason, B. and Moore, G.B. (Translated by Moore, F. and Sharafi, A.A.), 2003. Principles of Geochemistry. Shiraz University Press, Shiraz, 566 pp. (in Persian)
McDonough, W.F. and Sun, S.S., 1995. The composition of the Earth. Chemical Geology, 120(3-4): 223-253.
Monecke, T., Kempe, U. and Gotze, J., 2002. Genetic significance of the trace element content in metamorphic and hydrothermal quartz: a reconnaissance study Genetic significance of trace element content in quartz from hydrothermal ore deposit. Earth and Planetary Science Letters , 202(3-4): 709–724.
Moxon, T., 2002. Agate: A study of ageing. Europian Journal of Mineralogy, 14(6): 1109-1118.
Moxon, T. and Reed S.J.B., 2006. Agate and Chalcedony from Igneous and sedimentary hosts aged from 13 to 3480 Ma: a cathodoluminescence study. Mineralogical Magazine,70(5): 485-498.
Nazari M., 2004. Agates and Geodes from the Khur area, Central Iran. Australian Gemmologist, 22(1): 21-28.
Nazari, M., 2006a. Mineralogy and Genesis of geodes and agates of east of Khur and its relation with bentonite formation. 2th Symposium of geological society of Iran, Ferdwosi university, Mashhad. (in Persian with English abstract)
Nazari, M., 2006b. study of accessory minerals in khur agates and geodes by electronic microscope. 4th Symposium of geological society of Iran, Tabriz university, Tabriz (in Persian)
Passchier, C.W. and Trouw, R.A.J., 1996. Microtectonics. Springer-Verlag Berlin Heidelberg, New York, 366 pp.
gitashenasi geographical and cartographic institute, 2005. Road atlas of Iran. 271 pp. (in Persian)
Rollinson, H.R., 1993. Using geochemical data, Evaluation, Presentation, Interpretation. Longman Scientific and Technical, Michigan , 352 pp.
Taylor, H.P., 1980. The effect of assimilation of country rock by magma on 18O/16O and 87Sr/86Sr Systematics in igneous rocks. Earth Planetary Science Letter, 47(2): 243-254.
Technoexport, 1984a. Geological map of Khur area, scale 1:250,000. Geological Survey of Iran.
Technoexport, 1984b. Geology of the Khur area: Ministry of Mines and Metals. Geological survey of iIran, Tehran, Report 20, 132 pp.
Wang, Y. and Merino, E., 1995. Origin of Fibrosity and Banding in Agates from Flood Basalts. American Journal of Science, 295(1): 49-77.
Winchester, J.A. and Floyd, P.A., 1977. Geochemical classification of different magma series and their differentiation products using immobile elements. Chemical Geology, 20: 325–343.
CAPTCHA Image