ژئوشیمی و پتروژنز توده‌های نفوذی منطقه مهرآباد، شرق اردستان

نوع مقاله : علمی -پژوهشی

نویسندگان

1 استاد دانشکده زمین شناسی، پردیس علوم، دانشگاه تهران

2 کارشناسی ارشد دانشکده علوم زمین، پردیس علوم، دانشگاه تهران

3 استادیار گروه زمین شناسی، دانشکده علوم، دانشگاه کردستان

4 استادیار گروه زمین شناسی، دانشگاه پیام نور

چکیده

توده‌های نفوذی مهرآباد واقع در جنوب شرق اردستان، با سن تقریبی الیگوسن- میوسن، در بخش میانی کمربند ماگمایی ارومیه - دختر جای گرفته‌اند. این توده‌ها با ترکیب سنگ‌شناسی گرانیت، گرانودیوریت، تونالیت و کوارتز مونزودیوریت، در سنگ‌های آتشفشانی ائوسن منطقه تزریق شده‌اند. توده‌های نفوذی مورد مطالعه‌ با ماهیت کالک آلکالن و متا آلومین تا جزئی پرآلومین، جزو سنگ‌های گرانیتوئیدی نوع I محسوب می‌شوند. الگوی تغییرات عناصر کمیاب و کمیاب خاکی بهنجار شده به کندریت و گوشته اولیه بیانگر غنی‌شدگی این سنگ‌ها ازLREE  و  LILE نسبت به HREE و HFSE و وجود آنومالی منفیEu ، Nb،  Tiو P در نمونه‌های مورد مطالعه است. این امر در کنار موقعیت نمونه‌ها بر روی نمودارهای مختلف تمایز محیط تکتونیکی، حاکی از شکل‌گیری سنگ‌های مورد مطالعه در محیطی مرتبط با فرورانش در حاشیه فعال قاره‌ای است. شواهد ژئوشیمیایی مانند مقادیر بالای SiO2، مقادیر کم Mg# و عناصر انتقالی و همچنین میانگین نسبت‌های Nb/La، Nb/Ta، Ti/Zr، Nb/Ce و (La/Sm)n و نمودارهای تفکیک کننده خاستگاه ماگمایی، گویای آن است که پوسته زیرین با ترکیب متابازالتی، متاتونالیتی و آمفیبولیتی نقش مهمی در تشکیل توده گرانیتی مهرآباد بازی کرده است که در اثر گرمای ایجاد شده ناشی از ذوب بخشی گوشته در زون فرورانش، حاصل شده‌اند. AbstractMehrabad intrusive rocks, with probably Oligocene- Miocene age, located in the southeast of Ardestan, at the middle part of the Urumieh-Dokhtar magmatic belt. These rocks consist of granite, granodiorite, tonalite and quartz-monzodiorite that injected in the Eocene volcanic rocks of the area. Based on geochemical data, these intrusive bodies are calc-alkaline, meta-aluminium and I-type granitoid.  Primitive mantel-normalized and condrite-normalized of trace elements and rare elements patterns indicate enrichment in the LREE and LILE compared with HREE and HFSE and pronounced negative anomalies in Eu, Nb, Ti and P in the studied samples. Such geochemical characteristics along with position of samples on the various tectonic discrimination diagrams indicate that formation of these rocks are related to the subduction zone in the active continental margin. Geochemical evidences such as high SiO2, low Mg# and transitional elements, also Nb/La, Nb/Ta, Ti/Zr, Nb/Ce and (La/Sm)n average ratios and magmatic evolution discriminantion diagrams show that lower crust with meta-basalatic, meta-tonalitic and amphibolitic composition had played an important role in the formation of the granitic bodies of the Mehrabad region that generated by heat from partial melting of mantle at subduction zone. Keywords: Urumieh-Dokhtar, Geochemistry, Subduction, Continental crust, Mehrabad.

کلیدواژه‌ها


عنوان مقاله [English]

Geochemistry and Petrogenesis of the Intrusive Rocks, Mehrabad area, East Ardestan

چکیده [English]

Mehrabad intrusive rocks, with probably Oligocene- Miocene age, located in the southeast of Ardestan, at the middle part of the Urumieh-Dokhtar magmatic belt. These rocks consist of granite, granodiorite, tonalite and quartz-monzodiorite that injected in the Eocene volcanic rocks of the area. Based on geochemical data, these intrusive bodies are calc-alkaline, meta-aluminium and I-type granitoid.  Primitive mantel-normalized and condrite-normalized of trace elements and rare elements patterns indicate enrichment in the LREE and LILE compared with HREE and HFSE and pronounced negative anomalies in Eu, Nb, Ti and P in the studied samples. Such geochemical characteristics along with position of samples on the various tectonic discrimination diagrams indicate that formation of these rocks are related to the subduction zone in the active continental margin. Geochemical evidences such as high SiO2, low Mg# and transitional elements, also Nb/La, Nb/Ta, Ti/Zr, Nb/Ce and (La/Sm)naverage ratios and magmatic evolution discriminantion diagrams show that lower crust with meta-basalatic, meta-tonalitic and amphibolitic composition had played an important role in the formation of the granitic bodies of the Mehrabad region that generated by heat from partial melting of mantle at subduction zone.

کلیدواژه‌ها [English]

  • Urumieh-Dokhtar
  • Geochemistry
  • Subduction
  • Continental crust
  • Mehrabad
-اکبری، ک.، ١٣٧٨. مطالعه پتروگرافی و پترولوژی توده‌های نفوذی سهیل- پاکو و گلشکنان، پایان‌نامه کارشناسی‌ارشد، دانشگاه اصفهان.
-برکت، م.، ١٣٨٧. م‍طال‍ع‍ه‌ پ‍ت‍رول‍وژی‌ گ‍ران‍ی‍ت‍وئی‍ده‍ای‌ واق‍ع‌ در ش‍م‍ال‌ اردس‍ت‍ان‌ (ش‍ه‍رآب)، پایان‌نامه کارشناسی ارشد، دانشگاه آزاد اسلامی واحد خوراسگان.
-حمزه‌ای، ز.، ١٣٩١. پتروژنز توده نفوذی نصرند در جنوب شرق اردستان، پایان‌نامه کارشناسی‌ارشد دانشگاه تهران.
-سرجوقیان، ف.، ١٣٩١. ماهیت پلوتونیسم کوه‌دم (شمال شرق اردستان)، سرگذشت زمین‌شناسی و تحولات ماگمایی آن، رساله دکتری دانشگاه تهران.
-قفاری، م.، ١٣٨٩. پتروگرافی و ژئوشیمی توده گرانیتوئیدی ظفرقند (جنوب شرق اردستان)، پایان‌نامه کارشناسی دانشگاه شاهرود.
-قهرمانی، ف.، ١٣٩١. پتروژنز و ژئوشیمی آنکلاوهای توده نفوذی فشارک (شمال شرق اصفهان) پایان‌نامه کارشناسی‌ارشد دانشگاه تهران.
-عمیدی، م.، ١٩٧٧. بررسی ماگماتیسم در منطقه نطنز- نائین- سورک، پایان‌نامه دکتری و گزارش شماره ٤٢ سازمان زمین‌شناسی کشور.
-Alavi, M., 1994. Tectonic of the Zagros orogenic belt of Iran: Tectonophy, v. 299, p. 211-238.
-Altherr, R., Holl, A., Hegner, E., Langer, C. and Kreuzer, H., 2002. High-potassium, calc-alkaline plutonism in the European Variscides: northern Vosges (France) and northern Schwarzwald (Germany): Lithos, v. 50, p. 51–73.
-Amidi, S. M., 1977. Etude geologique de la region de Natnz-Surk (Central Iran) stratigraphie et. petrologie", Geology Survey of Iran, Rep, v. 42, 316 p.
-Armstrong, R.L., 1988. Geochronology and geology of the Eastern Great Basin: Ph.D. thesis, New Haven, CT, Yale University.
-Bacon, C.R. and Druitt, T.H., 1998. Compositional evolution of the zoned calc-alkaline magma chamber of Mt. Mazama, Crater Lake, Oregon: Contribution to Mineralogy and Petrology, v. 98, p. 244–256.
-Batchelor, R.A. and Bowden, P., 1985. Petrogenetic interpretation pf granitoid rock series using multicationic parameters: Chemical Geology, v. 48, p. 43-55.
-Berberian, M. and king, G.C.P., 1981. Towards a paleogeography and tectonic evolu tion of Iran: Canadian Journal of Sciences, v. 20, p. 163-183.
-Briqueu, L., Javoy, M., Lancelot, J.R. and Tatsumoto, M., 1986. Isotope geochemistry of recent magmatism in the Aegean arc: Sr, Nd, Hf, and O isotopic ratios in the lavas of Milos and santorini-geodynamic implication: Earth and Planetary Science Letters, v. 80, p. 41–54.
-Chappell, B. W. and White, A.J.R., 1974. Two contrasting granite type: Pacific Geology, v. 8, p. 173-174.
-Chappell, B.W., 1998. Tectonic evolution of the eastern Australian fold belts from a granite-based perspective: 1998 Mawson Lecture: The Australian Geologist, v. 109, p. 24-30.
-Chappell, B.W. and White, A.J.R., 1992. I- and S-type granites in the Lachlan Fold Belt, Transactions of the Royal Society of Edinburgh: Earth Sciences, v. 83, p. 1– 26.
-Collins, W.J., Beams, S.D., White, A.J.R. and Chappell, B.W., 1982. Nature and origin of A-type granites with particular reference to southeastern Australia: Contributions to Mineralogy and Petrology, v. 80, p. 189-200.
-De La Roche, H., Leterrier, J., Grande Claude, P. and Marchal, M., 1980. A classification of volcanic and plutonic rocks using R1-R2 diagrams and major element analyses_its relationship and current nomenclature: Chemical Geology, v. 29, p. 183-210.
-Defant, M.J. and Drummond, M.S., 1990. Derivation of some modern arc magmas by melting of young subducted lithosphere, Nature, v. 347, p. 662– 665.
-Fitton, J.G., James, D., Kempton, P.D., Ormerod, D.S. and Leeman, W.P., 1988. The role of lithosferic mantle in the generation of Late Cenozoic basic magmas in the Western United States: Journal of Petrology, v. 1, p. 331-349.
-Foden, J.D., Elburg, M.A., Turner, S.P., Sandiford, M., O'Callaghan, J. and Mitchell, S., 2002. Granite production in the Delamerian Orogen, South Australia: Journal of the Geological Society, v. 159, p. 557-575.
-Frost, B.R., Barnes, C.G., Collins, W.J., Arculus, R.J., Fllis, D.J. and Frost, C.D., 2001. A Geochemical Classification for Granitic Rocks: Journal of Petrology, v. 42, p. 2033-2048.
-Glenn, A.G., 2004. The influence of melt structure on trace element partitioning near the peridotite solidus: Contributions of Mineralogy and petrology, v. 147, p. 511-527.
-Grove, T.L. and Donnelly-Nolan, J., 1986. The evolution of young silicic lavas at Medicine Lake Volcano, California: Implications for the origin of compositional gaps in calc-alkaline lava series: Contributions of Mineralogy and petrology, v. 92, p. 281-302.
-Hildreth, W. and Moorbath, S., 1988. Crustal contributions to arc magmatism in the Andes of central Chile: Contributions to Mineralogy and Petrology, v. 98, p. 455-489.
-Hofmann, A.W., Jochum, K.P., Seufert, M. and White, M., 1986. Nb and Pb in oceanic basalts: new constraints on mantle evolution: Earth Planetary Sciences Letters, v. 79, p. 33-45.
-Hou, Z.-Q., Gao, Y.-F., Qu, X.-M., Rui, Z.-Y. and Mo, X.-X., 2004. Origin of adakitic intrusives generated during mid-Miocene east-west extension in southern Tibet: Earth and Planetary Science Letters, v. 220, p. 139-155.
-Irvine, T.N. and Barager, W.R.A., 1971. A guide to the chemical classification of the common volcanic rocks: Canadian Journal of Earth Sciences, v. 8, p. 523-545.
-Joron, J.L. and Treuil, M., 1977. Utilisation des proprietes des e1ements fortement hygromagmatophiles pour letude de la composition chimique et de heterogeneite du manteaux: Bulletin de La Society Geolque France, v. 19, p. 1197-1205.
-Jung, S., Masberg, P., Mihm, D. and Hoernes, S., 2009. Partial melting of diverse crustal sources – constraintsfrom Sr–Nd–O isotope compositions of quartz diorite-granodiorite leucogranite associations (Kaoko Belt, Namibia): Lithos, v.111, p. 236–51.
-Kampunzu, A.B., Tombale, A.R., Zhai, M., Bagai, Z., Majaule, T. and Modisi, M.P., 2003. Major and trace element geochemistry of plutonic rocks from Francistown, NE Botswana, evidence for a Neoarchaean continental active margin in the Zimbabwe craton, Lithos, v. 71, p. 431-460.
-Kistler, R.W., 1990. Two different lithosphere types in the Sierra Nevada, California, in Anderson, J.L., (eds.), The nature and origin of Cordilleran magmatism), Geological Society of America, Memoir, v. 174, p. 271–281.
-Kleeman, G.J. and Twist, d., 1989. The compositionally-zoned sheet-like granite pluton of the Bushveld complex: Evidence bearing on the nature of A-type mag matism, Journal of Petrology, v. 30, p. 1383-1414.
-Koprobasi, N. and Aldanmaz, E., 2004. Geochemical Constraints on the Petrogenesis of Cenozoic I-Type Granitoids in Northwest Anatolia, Turkey: Evidence for Magma Generation by Lithospheric Delamination in a Post-Collisional Setting: International Geology Review, v. 46, p. 705-729.
-Kuster, D. and Harms, U., 1998. Post-collisional potassic granitoids from the southern and northwestern parts of the Late Neoproterozoic East African Orogen: a review: Lithos, v. 4, p. 177-195.
-Leybourne, M., Wangoner, N.V. and Ayres, L., 1999. Partial melting of a refractory subducted slab in a Paleoproterozoic island arc: implications for global chemical cycles: Geology, v. 27 (8), p. 731–734.
-Maniar, P.D. and Piccoli, P.M., 1989. Tectonic discrimination of granitoids: Geology Society American Bulltion, v. 101, p. 635-643.
-Miller, C.F. and Barton, M.D., 1990. Phanerozoic plutonism in the Cordilleran interior, U.S.A., in: Kay, S.M. and Rapela, C.W., (eds.), Plutonism from Antarctica to Alaska: Geological Society of America Special Paper, v. 241, p. 213–232.
-Ormerod, D.S., Hawkesworth, C.J., Rogers, N.W., Leeman, W.P. and Menzies, M.A., 1988. Tectonic and magmatic transitions in the Western Great Basin, U.S.A.: Nature, v. 333, p. 349-353.
-Patiño Douce, A.E., 1999. What do experiments tell us about the relative contributions of crust and mantle to the origin of granitic magmas? In: Understanding granites. Integrating New and Classical Techniques, in: Castro, A. Fernandez C. and Vigneresse, J.L. (eds.), Geological Society, London, Special Publication, v. 158, p. 55-75.
-Pearce, J.A., 1983. Trace element characteristics of lavas from destructive plate boundaries, in: Thorpe, R.S., (eds.), Andesites, Wiley, New York, p. 525–548.
-Pearce, J.A., Harris, N.B.W. and Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks: Journal of Petrology, v. 25, p. 956- 983.
-Pitcher, W.S., 1993. The nature and origin of granite: London, Blackie Academic and Professional Publications, 321 p.
-Pourhosseini, F., 1983. Petrogenesis of Iranian plutons, A study of the Natanz and Bazman intrusive complexes, Ph.D these. G. S. I., v. 53, p. 325.
-Roberts, M.P. and Clemens, J.D., 1993. The origin of high-K, calcalkaline, I-type granitoid magmas: Geology, v. 21, p. 825–828.
-Rogers, N.W., Hawkesworth, C.J. and Ormerod, D.S., 1995. Late Cenozoic basaltic magmatism in the Western Great Basin California and Nevada: Journal of Geophysics Research, v. 100, p. 10287-10301.
-Rollinson, H.R., 1993. Using geochemical data: evaluation, presentation, interpretation: Longman scientific and technical, 252 p.
-Rottura, A., Bargossi, G.M., Caggianelli, A., Del Moro, A., Visona, D. and Tranne, C.A., 1998. Origin and significance of the Permian high-K calc-alkaline magmatism in the central-eastern Southern Alps, Italy: Lithos, v. 45, p. 329–348.
-Rudnick, R.L. and Fountain, D.M., 1995. Nature and composition of the continental crust, a lower crustal perspective, Review of Geophysics, v. 33, p. 267–309.
-Rushmer, T., 1991. Partial melting of 2 amphibolitea – contrsting experimental results under fluid-absent conditions, Contributions to Mineralogy and Petrology, v. 107(1), p. 41-59.
-Saunders, A.D., Tarney, J. and Weaver, S.D., 1980. Transverse geochemical variations across the Antarctic Peninsula, implication for the genesis of calc-alkaline magmas, Earth and planetary science Letters, v. 46, p. 344-360.
-Sengor, A.M.C., 1990. A new model for the late paleozoic-mesozoic tectonic evolut-ion of Iran and implication for Oman: Geological Society Special, v. 49, p. 797-831.
-Shelly, D., 1993. Igneous and metamorphic rocks under the microscope, Chapman and Hall, 445p.
-Sisson, T.W., Ratajeski, K., Hankins, W.B. and Glazner, A.F., 2005. Voluminous granitic magmas from common basaltic sources: Contributions to Mineralogy and Petrology, v. 148, p. 635-661.
-Stern, C.R. and Kilian, R., 1996. Role of the subducted slab, mantle wedge and continental crust in the generation of adakites from the Andean Austral volcanic zone, Contributions to Mineralogy and Petrology, v. 123, p. 263 281.
-Stöcklin, J., 1977. Structural correlation of the Alpine ranges between Iran and central Asia: Memoire Hors Serie - Societe Geologique de France, v. 8, p. 333-353.
-Streckeisen, A.L., 1976. To each plutonic rock its proper name, Earth: science review, v. 12, p. 1-33.
-Sun, S.S. and MCDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts, implications for mantle composition and processes, in: Saunders, A.D., Norry, M.J., (eds.), Magmatism in oceanic basins, Geologicla Society of London, Special Publication, v. 42, p. 313-345.
-Tepper, J.H., Nelson, B.K., Bergantz, G.W. and Irving, A.J., 1993. Petrology of the Chilliwack batholith, North Cascades, Washington, generation of calc-alkaline granitoids by melting of mafic lower crust with variable water fugacity, Contribution to Mineralalogy and Petrology, v. 113, p. 333-351.
-Thieblemont, D. and Tegyey, M., 1994. Une discrimination ge´ochimique des roches diffe´rencie´es te´moin de la diversite´ d’origine et de la situation tectonique des magmas, Comptes Rendus de l’Acade´mie des sciences, Paris, v. 319, p. 87–94.
-Tsuchiyama, A., 1985. Dissolution kinetics of plagioclase in the melt of the system diopside -albite - anorthite, and origin of dusty plagioclase in andesite, Contribution to Mineralalogy and Petrology, v. 89, p. 1-16.
-Vernon, R.H., 2004. A practical guide to rock microstructural, Cambridge, 594p.
-Weaver, B.L. and Tarney, J., 1984. Empirical approach to estimating the composition of the continental crust, Nature, v. 310, p. 575-577.
-Whalen, j.B., Currie, K.L. and Chappell, B.W., 1987. A-type granites, geochemical characteristics, discrimination and petrogenesis, Contrib, Mineral, Petrology, v. 95, p. 407-419.
-Wilson, M., 1989. Igneous petrogenesis a global tectonic approach, Unwin Hyman Ltd., London, 466p.
-Woodhead, J.D. and Johnson, R.W., 1993. Isotop and trace elementprofile across the new Britain Island arc Papua new guines, Contribution to Mineralalogy and Petrology, v. 113, p. 479-491.
-Wu, F.Y., Jahn, B.m., Wilde, S.A., Lo, C-H., Yui, T-F., Lin, Q., Ge, W-c. and Sun, D-y., 2003. Highly fractionated I-type granites in NE Chine (I): geochronology and petrogenesis: Lithos, v. 66, p. 241-273.
-Zen, E.A., 1986. Aluminum enrichment in silicate melts by fractional crystallization, some mineralogical and petrographic constraints, Journal of Petrology, v. 27, p. 1095–1118.