یافته‌های نوین زمین‌شناسی کاربردی

یافته‌های نوین زمین‌شناسی کاربردی

منشأ انکلاو­های مافیکی در کوهستان الوند (همدان): شواهدی از داده­ های سنگ‌نگاری و زمین‌شیمیایی

نویسندگان
1 دانش‌آموخته کارشناسی‌ارشد زمین‌شناسی، دانشکده علوم‌پایه، دانشگاه بوعلی‌سینا، همدان، ایران
2 دانشیار گروه زمین‌شناسی، دانشکده علوم‌پایه، دانشگاه بوعلی‌سینا، همدان، ایران
3 استادیار گروه زمین‌شناسی، دانشکده علوم‌پایه، دانشگاه بوعلی‌سینا، همدان، ایران
چکیده
کوهستان الوند یکی از بزرگ­ترین توده­‌های باتولیتی در بخش میانی پهنه سنندج- سیرجان است. این مطالعه به بررسی منشأ انکلاو­های مافیک در دایک‌­های همزمان با پلوتونیسم در این منطقه می‌پردازد. بر اساس روابط صحرایی و مشاهدات سنگ‌­نگاری، باتولیت­الوند از سنگ­‌های مافیک- فلسیک (گابرو، الیوین­گابرو، تونالیت، کوارتز دیوریت، کوارتز مونزودیوریت، مونزوگرانیت، سینوگرانیت و گرانیت) و انکلاوهای مافیک و دایک­‌های همزمان با پلوتونیسم تشکیل شده است. انکلاو­ها ریزدانه و مافیک­تر از سنگ میزبان هستند. آن­ها انکلاو­های میکروگرانولار ­مافیک (MMEs) هستند و دارای ترکیبی از سنگ‌های گرانودیوریتی به دیوریتی می­باشند. MMEsها عمدتاً بیضوی کشیده، با بلور­های درشت، مرز­های واضح با میزبان گرانیتوئیدی و همسو با جهت جریان ماگمای فلسیک هستند. میزبان­ها از نظر ترکیب گرانیتی می­باشند. داده­های زمین‌شیمیایی نشان می­دهد انکلاو­ها متاآلومینی­ و میزبان­ها پرآلومینی هستند و هر دو ماهیت کالک­آلکالن دارند. نتایج زمین‌شیمیایی در نمودار­های عنکبوتی بهنجار شده نشان می‌دهد که انکلاو­ها و میزبان‌­هایشان در LILEs غنی شده‌ و در HFSEها تهی شده­اند. در الگو­های بهنجار شده عناصر کمیاب خاکی، غنی­شدگی در LREE و تهی­شدگی در HREE‌ها دیده می­شود و غنی­شدگی در LREE در میزبان‌­ها بارزتر است. این ویژگی یکی از خصوصیات بارز ماگماهای کالک‌آلکالن در محیط قوس آتشفشانی است. در نمودار­های متمایز کننده محیط­های تکتونیکی، انکلاو­ها و میزبان­ها در جایگاه VAG قرار می­گیرند. بر اساس مطالعات سنگ‌نگاری و زمین‌شیمیایی، انکلاو­های میکروگرانولار­مافیک در یک فرآیند اختلاط / آمیختگی ماگمایی به دلیل عدم وجود فابریک­های رسوبی و بافت‌های کومولیتی، همراه با ویژگی‌­های اندازه دانه­بندی متفاوت تشکیل شدند.
کلیدواژه‌ها

عنوان مقاله English

Origin of mafic enclaves in the Alvand Mountains (Hamedan): evidence from petrographic and geochemical data

نویسندگان English

Parand Vermazyar 1
Ashraf Torkian 2
Leili Izadi Kian 3
1 M.Sc. Dept. of Geology, Faculty of Science, Bu-Ali Sina University, Hamedan, Iran
2 Assoc. Prof., Dept. of Geology, Faculty of Science, Bu-Ali Sina University, Hamedan, Iran
3 Assist. Prof., Dept. of Geology, Faculty of Science, Bu-Ali Sina University, Hamedan, Iran
چکیده English

The Alvand Mountains is one of the largest batholith bodies in the middle part of the Sanandaj-Sirjan zone. This study investigates the origin of mafic enclaves in syn-plutonic dykes in this area. Based on field relationships and petrographic observations, the Alvand batholith is composed of mafic –felsic rocks (gabbro, olivine gabbro, tonalite, quartz diorite, quartz monzodiorite, monzogranite, syen­ogranite and granite) and mafic enclaves and syn-plutonic dykes. Enclaves are fine-grained and more mafic than host rock. They are mafic microgranular enclaves (MMEs) and have the composition of granodioritic to dioritic rocks. MMEs are mostly elongated ellipsoids, with coarse crystals, clear boundaries with the granitoid host, and aligned with the flow direction of felsic magma. The hosts are granitic in composition. Geochemical data display enclaves are metaaluminous and the hosts are peraluminous, and both are the calc-alkaline in nature. Geochemical results in spider- normalized diagrams indicate enclaves and their hosts are enriched in LILEs and depleted in HFSEs. In the rare earth element-normalized patterns, they show enrichment in LREEs and depletion in HREEs and enrichment in LREEs is more pronounced in hosts. This feature is one of the prominent characteristics of the calc-alkaline magmas in a volcanic arc environment. In discrimination tectonic setting diagrams, enclaves and hosts are plotted on the VAG field. Based on petrographic and geochemical studies, the microgranular mafic enclaves formed in a magmatic mixing/mingling process due to the absence of sedimentary fabrics and cumulative textures, along with different grain size characteristics.

کلیدواژه‌ها English

Enclave
Alvand
Sanandaj-Sirjan
magmatic mixing
Altherr, R., Holl, A., Hegner, E., Langer, C. and Kreuzer, H. (2000) High-potassium, calc-alkaline, I-type plutonism in the European Variscides: northern Vosges (France) and northern Schwarzwald (Germany). Lithos 50: 51-73.
Azizi, H., and Jahangiri, A. (2008) Cretaceous subduction-related volcanism in the northern Sanandaj-Sirjan zone, Iran: Journal of Geodynamics, 45: 178–190.    https://doi.org/10.1016/j.jog.2007.11.001.
Azizi, H., and Stern, R. J. (2019) Jurassic igneous rocks of the central Sanandaj–Sirjan zone (Iran) mark a propagating continental rift, not a magmatic arc: Terra Nova, 31: 415–423.
Bacon, C. R. and Druitt, T. H. (1988) Compositional evolution of the zoned calc-alkaline magma chamber of Mount Mazama, Crater Lake, Oregon. Contributions to Mineralogy and Petrology 98: 224-256. https://doi.org/10.1007/bf00402114.
Badr, A., Davoudian, A. R., Shabanian, N., Azizi, H., Asahara, Y., Neubauer, F., Dong, Y., and Yamamoto, K. (2018) A-and I-type metagranites from the North Shahrekord metamorphic complex, Iran: Evidence for early Paleozoic post-collisional magmatism: Lithos, 300: 86–104.
Barbarin, B. (2005) Mafic magmatic enclaves and mafic rocks associated with some granitoids of the central Sierra Nevada batholith, California: nature, origin, and relations with the hosts, Lithos, 88: 155–177.
Barbarin, B. (1989) Importance des différents processus d’hybridation dans les plutons granitiques du batholite de la Sierra Nevada, Californie. Schweiz Mineral Petrogr. Mitt, 69: 303–315.
Barbarin, B. and Didier, J. (1992) Genesis and evolution of mafic microgranular enclaves through various types of interaction between coexisting felsic and mafic magmas. Transactions of the Royal Society of Edinburgh Earth Sciences, 83: 145-153. https://doi.org/10.1017/s0263593300007835.
Baxter, S., and Feely, M. (2002) Magma mixing and mingling textures in granitoids: examples from the Galway Granite, Connemara, Ireland. Mineralogy and Petrology, 76 (1-2): 63-74. https://doi.org/10.1007/s007100200032.
Bullen, T. D., and Clynne, M. A. (1990) Trace element and isotopic constraints on magmatic evolution at Lassen volcanic center. Journal of Geophysical Research, 95: 19671-19691. https://doi.org/10.1029/jb095ib12p19671.
Bussy, F., and Ayrton, S. (1990) Quartz textures in dioritic rockes of hybrid origin. Schweizerische Mineralogische und Petrographische Mitteilungen, 70: 223-235.
Chappell, B. W., White, A. J. R., and Wyborn, D. (1987) The importance of residual source material (restite) in granite petrogenesis. Journal of Petrology, 28: 1111-1138.
Clemens, J. D., Wall, V. J. (1984) Origin and evolution of a peraluminous silicic ignimbrite suite: the Violet Town Volcanics. Lithos 88: 354–371.
Clemens, J. D., Wall, V. J. (1988) Controls on the mineralogy of S-type volcanic and plutonic rocks. Lithos, 21: 53–66
Clemens, J. D., and Wall, V. J. (1988) Controls on the mineralogy of S-type volcanic and plutonic Rocks. Lithos, 21: 53-66. Dadfar, S., Aliani, F., Baharifar, A. A. and Zarrinkoub, M. H. (2019) Study of origin and petrogenesis of granitoid bodies of Soursat complex (Northwest of Takab): whole-rock geochemical and Sr-Nd evidences. Petrology, 9(36): 1-24 (in Persian)
Daneshvar, N., Maanijou, M., Azizi, H., and Asahara, Y. (2019) Petrogenesis and geodynamic implications of an Ediacaran (550 Ma) granite complex (metagranites), southwestern Saqqez, northwest Iran. Journal of Geodynamics, 132, p. 101669.
Didier, J. (1987) Contribution of enclave studies to the understanding of origin and evolution of granite magmas. Geologische Rundschau, 76: 41-50. https://doi.org/10.1007/bf01820572.
Didier, J., and Roques, M. (1959) Sur les Enclaves des granites du Massif Central Francais. C. R. Acad.Sci. paris, 228: 1839-1841.
Feeley, T. C., Wilson, L. G., Underwood, S. J. (2008) Distribution and compositions magmatic inclusions in the Mount Helen dome, Lassen volcanic center, California: insights into magma chamber processes, Lithos, 106: 173–189. https://doi.org/10.1016/j.lithos.2008.07.010.
Ferre, E. C., Caby, C., Peucat, J. J, Capdevila, R. and Monie, P. (1998) Pan-African, post-collisional, ferro-potassic granite and quartz-monzonite plutons of Eastern Nigeria. Lithos, 45: 255–279.
Ghalamghash, J., Mohammadiha, K., Rashid, H and Ghahraeipour, M. (2004) Mafic and felsic magma mingling and mixing in Alvand pluton: implication for magma emplacement. 23th Geoscience Symposium Geological Survey of Iran.
Gholipour, S., Azizi, H., Masoudi, F., Asahara, Y., and Tsuboi, M. (2021) Zircon U-Pb ages, geochemistry, and Sr-Nd isotope ratios for early cretaceous magmatic rocks, southern Saqqez, northwestern Iran: Geochemistry, 81: p. 125687. https://doi.org/10.1016/j.chemer.2020.125687.
Gou, L., Zhang, L., Tao, R. and Du, J. (2012) A geochemical study of syn-subduction and post-collisional granitoids at Muzhaerte River in the southwest Tianshan UHP belt, NW China. Lithos, 136-139: 201- 224.
Grove, T. L. and Donnelly-Nolan, J. M. (1986) The evolution of young silicic lavas at Medicine Lake Volcano, California: Implications for the origin of compositional gaps in calc-alkaline series lavas. Contributions to Mineralogy and Petrology, 92: 281-302.
Guffanti, M., Clynne, M. A. and Muffler, L. J. P. (1996) Thermal and mass implications of magmatic evolution in the Lassen volcanic region, California, and minimum constraints on basalt influx to the lower crust. Journal of Geophysical Research, 101: 3001-3013. https://doi.org/10.1029/95jb03463.
Harker, A. (1909) The natural history of igneous rocks. Methuen and Co. London. https://doi.org/10.1017/s0016756800124744.
Irvine, T. N., Baragar, W. R. A. (1971) A guide to the chemical classification of the common volcanic rocks, Canadian Journal of Earth Sciences, 8: 523–548.
Izadi Kian, L. (2011) Structural analysis of Ganjnameh- Shahrestaneh area (SW Hamedan), New finding in Applied Geology, 5(9): 17-29.
Kolb, M., Von Quadt, A., Peytcheva, I., Heinrich, C. A., Fowler, S. J. and Cvetković, V. (2013) Adakite like and normal arc magmas: distinct fractionation paths in the East Serbian segment of the Balkan Carpathian arc. Journal of Petrology, 54: 421-451.
Kumar, S. (2010) Mafic to hybrid microgranular enclaves in the Ladakh batholith, northwestern Himalaya: implications on calc-alkalin magma chamber processes. Journal of Geological Society of India, 76: 5-25. https://doi.org/10.1007/s12594-010-0080-2.
Kumar, S. (2014) Magmatic processes: review of some concepts and models, in Modelling of magmatic and allied processes. Editors S Kumar and R. N. Singh (Cham, Switzerland: Springer-Switzerland), 1–22.
Kumar, S., Rino, V., and Pal, A. B. (2004) Field evidence of magma mixing from microgranular enclaves hosted in Palaeoproterozoic Malanjkhand granitoids, Central India. Gondwana Research, 7 (2): 539-548.
Lacroix, A. (1933) Sur Quelques granites des environs de Porto. An fac. Cienc. Porto, 18: 35–68.
Maniar, P. D., Piccoli, P. M. (1989) Tectonic discrimination of granitoids, Geological Society of America Bulletin, 101: 635–643.
Middlemost, E. A. K. (1994) Naming materials in the magma/igneous rock system. Earth Sci. Reviews, 37: 215–224.
Miyashiro, A. (1974) Volcanic rock series in island arcs and active continental margins. American Journal of Science, 274: 321–355. https://doi.org/10.2475/ajs.274.4.321.
Mohamed, F. H., Moghazi, A. M. and Hassanen, M. A. (2000) Geochemistry, petrogenesis and tectonic setting of late Neoproterozoic Dokhan-type volcanic rocks in the Fatira area, eastern Egypt. International Journal of Earth Sciences (Geologische Rundschau), 88: 764-777. https://doi.org/10.1007/s005310050304.
Nakamura, N. (1974) Determination of REE, Ba, Fe, Mg, Na and K in carbonaceous and ordinary chondrites. Geochimica et Cosmochimica Acta 38: 757-775.
Pabst, A. (1928) Observation on inclusion on the granitic Rocks of the Sierra Nevada. Univ. Calif. publ. Dep. Geol. Sci., 17: 325-386.
Patino ˜ Douce, A. E. (1999) What do experiments tell us about the relative contributions of crust and mantle to the origin of granitic magmas? Geological Society, London, Special Publications, 168 (1): 55–75.
Patino Douce, A. E. and Beard, J. S. (1996) Effects of P, f (O2) and Mg/Fe ratio on dehydration melting of model metagreywackes. Journal of Petrology, 37: 999-1024. 
Pearce, J. A., Harris, N. B., Tindle, A. G. (1984) Trace element discrimination diagrams for the tectonic interpretation of granitic rocks, Journal of Petrology, 25: 956-983.
Pearce, J. A. (1983) Role of the sub-continental lithosphere in magma genesis at active continental margins. In: Continental Basalts and Mantle Xenoliths (Eds. Hawkesworth, C. J. and Norry, M. J.) 230-249. Shiva, Nantwich.
Phillips, G. N., Wall, V. J., Clemens, J. D. (1981) Petrology of the Strathbogie batholith: a cordierite-bearing granite. Can Mineral, 19: 47–63.
Pitcher, W. S. (1993) The nature and origin of granite. Chapman & Hall, London 321p. https://doi.org/10.1007/978-94-017-3393-9.
Reid, J. R., Evans, O. C. and Fates, D. G. (1983) Magma mixing in granitic rocks of the central Seirra Nevada, California. Earth and Planetary Science Letters, 66: 243-261.
Roberts, M. P. and Clemens, J. D. (1993) Origin of high-potassium, calc-alkaline, I-type granitoids. Geology, 21: 825-828.
Rollinson, H. R. (1993) Using geological data, evolution, presentation, interpretation. Longman Ltd Pupulation, London. 352p.
Shand, S. J. (1943) Eruptive rocks, Their genesis, composition, classification, and their relations to ore - deposits with a Chapter on Meteorite, New York: John Wiley and Sons, Inc., New York.
Silva, M. M. V. G., Neiva, A. M. R. and Whitehouse, M. J. (2000) Geochemistry of enclaves and host granites from the Nelas area, central Portugal. Lithos, 50: 153-170.
Sollas, J. W. (1894) On the volcanic district of Calingford and Slieve Gullion. I: On the relation of the granite to the gabbro of Barnavarve. Trans. R. Irish Acad, 30: 477–512.
Sun, S. S. and McDonough, W. F. (1989) Chemical and isotopic systematic of oceanic basalts: implication for mantle compositions and processes. In: Magmatism in ocean basins (Eds. Saunders, A. D. and Norry, M. J.) Geological Society Publication of London, 42: 313-345.
Tatsumi, Y., Nakashima, T., and Tamura, Y. (2002) The petrology and geochemistry of calc-alkaline Andesite on Shodo-Shima Island, SW Japan. Journal of Petrology, 43(1): 3-16. https://doi.org/10.1093/petrology/43.1.3.
Taylor, S. R. and McLennan, S. M. (1985) The continental crust: its composition and evolution. Blackwell, Oxford. 312p.
Tepper, J. H., Nelson, B. K., Bergantz, G. W., 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, Contributions to Mineralogy and Petrology, 113: 333-351.
Thompson, R. N. (1982) British Tertiary volcanic province. Scottish Journal of Geology, 18: 49-107. https://doi.org/10.1144/sjg18010049.
Vernon, R. H. (1990) Crystallization and hybridism in microgranitoid enclave magmas: microstructural Evidence. Journal of Geophysical research: Solid Earth, 95(B11): 17849-17859.
Whitney, D. L. and Evans, B. W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95(1): 185-187.
Wilson, M. (1989) Igneous petrogenesis: A global tectonic approach. London, Unwin Hyman, London. 446p.
Wolf, M. B. and Wyllie, J. P. (1994) Dehydration-melting of amphibolite at 10 Kbar: the effects of temperature and time. Contributions to Mineralogy and Petrology, 115: 369-383. https://doi.org/10.1007/bf00320972.
Xu, X., Dong, C., Li, W., and Zhou, X. (1999) Late Mesozoic intrusive complex in the coastal area of Fujian, SE China: the significance of the gabbro-diorite-granite association. Lithos, 46: 299-315.
Zhao, Z., Wang, C. Y., Wei, B. and Dou, J. (2021) Elemental and Nd isotopic compositions of zoned titanite in mafic microgranular enclaves of the Early Cretaceous Sanguliu granitic pluton in the North China Craton: Insights into magma mixing process. Lithos, 392-393: 106138. https://doi.org/10.1016/j.lithos.2021.106138.

  • تاریخ دریافت 16 فروردین 1404
  • تاریخ بازنگری 10 خرداد 1404
  • تاریخ پذیرش 01 تیر 1404