پتروژنز سنگهای آداکیتی پس از تصادم پلیو کواترنری در شمالغرب مرند | ||
| مجله بلورشناسی و کانی شناسی ایران | ||
| مقاله 15، دوره 18، شماره 4 - شماره پیاپی 40، دی 1389، صفحه 709-722 اصل مقاله (2.7 M) | ||
| نویسندگان | ||
| غلامرضا احمدزاده* 1؛ احمد جهانگیری2؛ منصور مجتهدی2؛ دیوید لنتز3 | ||
| 1انشگاه محقق اردبیلی | ||
| 2دانشگاه تبریز | ||
| 3دانشگاه نیو برانزویک | ||
| چکیده | ||
| در شمالغرب مرند در بخش شمالی نوار آتشفشانی ارومیه-دختر مجموعهای از سنگهای آتشفشانی با ترکیب آندزیت، داسیت، بازالتهای سدیک، پتاسیک و اولتراپتاسیک قلیایی برونزد دارند که در گسترهی زمانی میوسن بالائی تا کواترنری به سطح زمین راه یافتهاند. این مقاله به بخش ترکیبهای آندزیتی و داسیتی این سنگها می پردازد که بهطور پراکنده از داخل مجموعه آذرآواری بیرون ریختهاند. این سنگهای آتشفشانی دارای بافت پرفیری هستند که شامل فنوکریستهای پلاژیوکلاز، هورنبلند، پیروکسن و به مقدار کم بیوتیت هستند. از لحاظ ژئوشیمیایی این سنگها دارای مقادیرSiO2 در گسترهی 8/67 – 5/57 درصد وزنی، Al2O3 (5/14 تا 3/16)،Sr (577- 1185) بالا، نسبتهای بالای Sr/Y (7/30- 46/84) و La/Yb (27/13- 36/61) و مقادیر پایین Y (2/11-2/20) هستند که نشاندهنده ویژگی آداکیتی این ماگماها هستند. ویژگیهای ژئوشیمیائی نمونههای منطقهی با آداکیتهای پر سیلیس (Sr<1100 ppm, Na2O+K2O<11 %wt, MgO = 0.85-3.5) همخوانی دارد که نشان میدهد آداکیتهای منطقهی مورد بررسی همانند آداکیتهای پرسیلیس از ذوب صفحهی بازالتی فرورونده به وجود آمدهاند. همچنین این سنگها از عناصر LILEs و LREEs غنیشدگی نشان میدهند (33/6- 39/26(Ce/Yb)N=) و دارای تهیشدگی نسبی از عناصر انتخابی HFSEs مانند Ta, Ti و Nb هستند. الگوی شدید جدایشی در REE و نیز مقادیر پایین HREEs و Y ممکن است به دلیل وجود گارنت و یا آمفیبول در پسماندهی جامد ماگمای این سنگها باشد. همچنین مقادیر بالای استرانسیم و بیهنجاری منفی تانتالیم، نیوبیوم و تیتانیم میتواند نشانگر عدم حضور پلاژیوکلاز و حضور اکسیدهای آهن و تیتان در تفالهی باقیماندهی ذوب باشد. ویژگیهای ژئوشیمیائی سنگهای منطقه نشان میدهند که شکسته شدن صفحهی اقیانوسی فرورونده و ذوب باقیماندهی این صفحه موجب تولید ماگماتیسم آداکیتی منطقهی شمالغرب مرند شدهاند. همچنین بالا بودن مقادیر باریم، توریم و روبیدیم میتواند در اثر آغشتگی ماگما با مواد پوستهای در طول صعود ماگماست. | ||
| کلیدواژهها | ||
| آداکیت؛ نئوتتیس؛ فرورانش؛ نوار ماگمائی ارومیه – دختر و شمالغرب ایران | ||
| مراجع | ||
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[1] Denfant M.J., Drummond M.S., "Derivation of some modern arc magmas by melting of young subducted lithosphere". Nature 347 1990 662–665. [2] Wang Q., McDermott F., Xu J.F., Bellon H., Zhu Y.T., "Cenozoic K-rich adakitic volcanic rocks in the Hohxil area, northern Tibet: lower-crustal melting in an intracontinental setting". Geology 33, 2005. 465–468. [3] Guo Z., Wilson M., Liu J., "Post-collisional adakites in south Tibet: products of partial melting of subduction-modified lower crust.", Lithos 96, 2007. 205–224. [4] Grove T. L., Baker M.B., Price R.C., Parman S.W., Elkins-Tanton L.T., Chatterjee N., Müntener O., "Magnesian andesite and dacite lavas from Mt. Shasta, northern California: products of fractional crystallization of H2O-rich mantle melts", Contributions to Mineralogy and Petrology, v. 148, 2005, p. 542-565. [5] Green N.L., Harry D.L, "On the relationship between subducted slab age and arc basalt petrogenesis, Cascadia subduction system", North America: Earth and Planetary Science Letters, v. 171, 1999, p.367-381. [6] Alavi M., "Regional stratigraphy of the Zagros folded-thrust belt of Iran and its proforeland evolution.", Am. J. Sci. 304, 2004. 1–20. [7] Ahmadzadeh G.R., "Petrographical and Petrological Studies of Volcanic Rocks in NW of Marand (north of Galleban)". Unpublished M.Sc. thesis, University of Tabriz, 2002. 114pp, (in Persian). [8] Omrani J., et al., "Arc-magmatism and subduction history beneath the Zagros Mountains", Iran: A new report of adakites and geodynamic consequences, Lithos (2008),. doi:10.1016/j.lithos.2008.09.008 [9] Jahangiri A., "Post-collisional Miocene adakitic volcanism in NW Iran: geochemical and geodynamic implications". Journal of Asian Earth Sciences 30, 2007. 433–447. [10] Ahmadzadeh G.R., "Petrological Studies of Volcanic Rocks in NW of Marand spatially alkaline rocks. Unpublished P.H.D thesis", University of Tabriz, 2010. 247pp, (in Persian). [11] LeBas M.J., Le Maitre R.W., Streckeisen A., Zanettin B., "A chemical classification of volcanic rocks on the total alkali-silica diagram", J. Petrol. 27, 745–750. [12] MacLean W.H., Barrett T.J., "Lithochemical techniques using immobile elements", Journal of Geochemical Exploration 48, 1993. 109–133. [13] Martin H., Smithies R.H., Rapp R., Moyen J.-F., Champion D., "An overview of adakite, tonalite–trondhjemite–granodiorite (TTG), and sanukitoid: relationships and some implications for crustal evolution", Lithos 79, 2005. 1–24. [14] Boynton W.V., "Geochemistry of the rare earth elements: meteorite studies. In: Henderson", P. (Ed.), Rare Earth Element Geochemistry. Elsevier, 1984. pp. 63– 114. [15] Pearce J.A., "Role of the sub-continental lithosphere in magma genesis at active 594 continental margins. In: C.J. Hawkesworth & M.J., Norry, eds. Continental 595 Basalts and Mantle Xenoliths. Shiva Press", Nantwich, U.K., 1983. pp 230-249. [16] Muller D., Rock N.M.S., Groves D.I., "Geochemical discrimination between shoshonitic and potassic volcanic rocks from different tectonic setting: a pilot study", Mineralogy and Petrology 46, 1992. 259-289. [17] Martin H., "Adakitic magmas: modern analogues of Archaean granitoids", Lithos 46, 1999. 411– 429. [18] Plank T., "Constraints from Thorium/Lanthanum on sediment recycling at subduction zones and the evolution of the continents", Journal of Petrology 46, 2005. 921–944. [19] Wang Q., Wyman D.A., Xu J.F., Wan Y.S., Li C.F., Zi F., Jiang Z.Q., Qiu H.N., Chu Z.Y., Zhao Z.H., Dong Y.H., "Triassic Nb-enriched basalts, magnesian andesites, and adakites of the Qiangtang terrane (Central Tibet): evidence for metasomatism by slabderived melts in the mantle wedge", Contributions to Mineralogy and Petrology 155, 2008. 473– 490. [20] Rapp R.P., Watson E.B., "Dehydration melting of metabasalt at 8–32 kbar: implications for continental growth and crust–mantle recycling", Journal of Petrology 36, 1995. 891–931. [21] Klemme S., Blundy J.D., Wood B.J., "Experimental constraints on major and trace element partitioning during partial melting of eclogite", Geochimica et Cosmochimica Acta 66, 2002. 3109–3123. [22] Sorensen S.S., Barton M.D., "Metasomatism and partial melting in a subduction complex Catalina schist", southern California. Geology 15, 1987. 115–118. [23] Kay S.M., Gody E., Kurtz A., "Episodic arc migration, crustal thickening, subduction erosion and magmatism in the south-central Andes", Geological Society of America Bulletin 117, 2005. 67–88. [24] Peacock S.M., Rushmer T., Thompson A.B., "Partial melting of subducting oceanic crust: Earth and Planetary Science Letters", v. 121, 1994, p. 227-244. [25] Xu J.F., Shinjio R., Defant M.J., Wang Q., Rapp R.P., "Origin of Mesozoic adakitic intrusive rocks in the Ningzhen area of east China: partial melting of delaminated lower continental crust", Geology 12, 2002. 1111–1114. [26] Dehghani G.A., Makris J., "The gravity field and crustal structure of Iran, N. Jb. Geol. Palaeont". Abh., 168, 1984. 215–229. [27] Nicolas A., "Structures in Ophiolites and Dynamics of Oceanic Lithosphere. Kluwer", Dordrecht. 1989. 367 pp. [28] Searle M.P., Cox J., "Tectonic setting, origin and obduction of the Oman ophiolite. Geological Society of America Bulletin", 111, 1999. 104–122. [29] Sun S.-s., McDonough W.F., "Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes", In: Saunders, A.D., Norry, M.J. (Eds.), Magmatism in the Ocean Basins. Geological Society, London, pp. 313–345. [1] Denfant M.J., Drummond M.S., "Derivation of some modern arc magmas by melting of young subducted lithosphere". Nature 347 1990 662–665. [2] Wang Q., McDermott F., Xu J.F., Bellon H., Zhu Y.T., "Cenozoic K-rich adakitic volcanic rocks in the Hohxil area, northern Tibet: lower-crustal melting in an intracontinental setting". Geology 33, 2005. 465–468. [3] Guo Z., Wilson M., Liu J., "Post-collisional adakites in south Tibet: products of partial melting of subduction-modified lower crust.", Lithos 96, 2007. 205–224. [4] Grove T. L., Baker M.B., Price R.C., Parman S.W., Elkins-Tanton L.T., Chatterjee N., Müntener O., "Magnesian andesite and dacite lavas from Mt. Shasta, northern California: products of fractional crystallization of H2O-rich mantle melts", Contributions to Mineralogy and Petrology, v. 148, 2005, p. 542-565. [5] Green N.L., Harry D.L, "On the relationship between subducted slab age and arc basalt petrogenesis, Cascadia subduction system", North America: Earth and Planetary Science Letters, v. 171, 1999, p.367-381. [6] Alavi M., "Regional stratigraphy of the Zagros folded-thrust belt of Iran and its proforeland evolution.", Am. J. Sci. 304, 2004. 1–20. [7] Ahmadzadeh G.R., "Petrographical and Petrological Studies of Volcanic Rocks in NW of Marand (north of Galleban)". Unpublished M.Sc. thesis, University of Tabriz, 2002. 114pp, (in Persian). [8] Omrani J., et al., "Arc-magmatism and subduction history beneath the Zagros Mountains", Iran: A new report of adakites and geodynamic consequences, Lithos (2008),. doi:10.1016/j.lithos.2008.09.008 [9] Jahangiri A., "Post-collisional Miocene adakitic volcanism in NW Iran: geochemical and geodynamic implications". Journal of Asian Earth Sciences 30, 2007. 433–447. [10] Ahmadzadeh G.R., "Petrological Studies of Volcanic Rocks in NW of Marand spatially alkaline rocks. Unpublished P.H.D thesis", University of Tabriz, 2010. 247pp, (in Persian). [11] LeBas M.J., Le Maitre R.W., Streckeisen A., Zanettin B., "A chemical classification of volcanic rocks on the total alkali-silica diagram", J. Petrol. 27, 745–750. [12] MacLean W.H., Barrett T.J., "Lithochemical techniques using immobile elements", Journal of Geochemical Exploration 48, 1993. 109–133. [13] Martin H., Smithies R.H., Rapp R., Moyen J.-F., Champion D., "An overview of adakite, tonalite–trondhjemite–granodiorite (TTG), and sanukitoid: relationships and some implications for crustal evolution", Lithos 79, 2005. 1–24. [14] Boynton W.V., "Geochemistry of the rare earth elements: meteorite studies. In: Henderson", P. (Ed.), Rare Earth Element Geochemistry. Elsevier, 1984. pp. 63– 114. [15] Pearce J.A., "Role of the sub-continental lithosphere in magma genesis at active 594 continental margins. In: C.J. Hawkesworth & M.J., Norry, eds. Continental 595 Basalts and Mantle Xenoliths. Shiva Press", Nantwich, U.K., 1983. pp 230-249. [16] Muller D., Rock N.M.S., Groves D.I., "Geochemical discrimination between shoshonitic and potassic volcanic rocks from different tectonic setting: a pilot study", Mineralogy and Petrology 46, 1992. 259-289. [17] Martin H., "Adakitic magmas: modern analogues of Archaean granitoids", Lithos 46, 1999. 411– 429. [18] Plank T., "Constraints from Thorium/Lanthanum on sediment recycling at subduction zones and the evolution of the continents", Journal of Petrology 46, 2005. 921–944. [19] Wang Q., Wyman D.A., Xu J.F., Wan Y.S., Li C.F., Zi F., Jiang Z.Q., Qiu H.N., Chu Z.Y., Zhao Z.H., Dong Y.H., "Triassic Nb-enriched basalts, magnesian andesites, and adakites of the Qiangtang terrane (Central Tibet): evidence for metasomatism by slabderived melts in the mantle wedge", Contributions to Mineralogy and Petrology 155, 2008. 473– 490. [20] Rapp R.P., Watson E.B., "Dehydration melting of metabasalt at 8–32 kbar: implications for continental growth and crust–mantle recycling", Journal of Petrology 36, 1995. 891–931. [21] Klemme S., Blundy J.D., Wood B.J., "Experimental constraints on major and trace element partitioning during partial melting of eclogite", Geochimica et Cosmochimica Acta 66, 2002. 3109–3123. [22] Sorensen S.S., Barton M.D., "Metasomatism and partial melting in a subduction complex Catalina schist", southern California. Geology 15, 1987. 115–118. [23] Kay S.M., Gody E., Kurtz A., "Episodic arc migration, crustal thickening, subduction erosion and magmatism in the south-central Andes", Geological Society of America Bulletin 117, 2005. 67–88. [24] Peacock S.M., Rushmer T., Thompson A.B., "Partial melting of subducting oceanic crust: Earth and Planetary Science Letters", v. 121, 1994, p. 227-244. [25] Xu J.F., Shinjio R., Defant M.J., Wang Q., Rapp R.P., "Origin of Mesozoic adakitic intrusive rocks in the Ningzhen area of east China: partial melting of delaminated lower continental crust", Geology 12, 2002. 1111–1114. [26] Dehghani G.A., Makris J., "The gravity field and crustal structure of Iran, N. Jb. Geol. Palaeont". Abh., 168, 1984. 215–229. [27] Nicolas A., "Structures in Ophiolites and Dynamics of Oceanic Lithosphere. Kluwer", Dordrecht. 1989. 367 pp. [28] Searle M.P., Cox J., "Tectonic setting, origin and obduction of the Oman ophiolite. Geological Society of America Bulletin", 111, 1999. 104–122. [29] Sun S.-s., McDonough W.F., "Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes", In: Saunders, A.D., Norry, M.J. (Eds.), Magmatism in the Ocean Basins. Geological Society, London, pp. 313–345. | ||
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