نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه زمین شناسی دانشکده علوم - دانشگاه لرستان- خرم آباد

2 دانشکده علوم پایه، گروه زمین شناسی، دانشگاه لرستان، خرم آباد، ایران

چکیده

منطقه مورد مطالعه در شمال تا شمال غرب شهرستان رابر در استان کرمان قرار دارد و جزئی از کمربند ماگمایی ارومیه-دختر محسوب می شود. در این منطقه توده‌های نفوذی متعددی با ترکیب غالب دیوریت، گرانودیوریت و گرانیت در واحدهای آتشفشانی رخنمون دارد. سنگ-های مورد مطالعه بر اساس ویژگی های ژئوشیمیایی به دو گروه تقسیم بندی شده اند: 1) گرانیتوئیدهای آداکیتی که با میزان سیلیس (78/66-49/61 درصد وزنی)، Al2O3 (74/17 – 72/15 درصد وزنی)، Sr (ppm 602 -374)، Sr/Y (53-34) و نسبت (La/Yb)N بین 88/16-35/8 و مقادیر اندک Y مشخص می‌شوند. 2) گرانیتوئیدهای کالک‌آلکالن که مهمترین خصوصیات آنها عبارتند از: میزان سیلیس (32/72-07/63 درصدوزنی)، نسبت‌های پایین Sr/Y (22/13-83/3)، مقادیر بالای Y ( ppm6/31-7/21) و Yb ( ppm26/3-29/2)، میزان Sr کمتر بین ppm 297-119 و نسبت 13/11-02/3 = (La/Yb)N پایین‌تر نسبت به گروه آداکیت‌ها با آنومالی منفی Eu [(Eu/Eu*)N= (ave. 0.49)]. سنگ-های آداکیتی احتمالاً از پوسته زیرین مافیک (آمفیبولیت گارنت‌دار) همراه با گارنت + روتیل ± پلاژیوکلاز بعنوان فازهای باقیمانده در محل منبع در عمقی بیشتر از 50 کیلومتر تشکیل شده‌اند و گروه کالک‌آلکالن نیز احتمالاً در اعماق نزدیک‌تر به سطح زمین نسبت به آداکیت‌ها در پوسته میانی-زیرین با ترکیب سنگی غالب آمفیبولیت تشکیل شده‌اند. بررسی نسبت‌های ایزوتوپی اولیه (704871/0 - 705195/087Sr/ 86 Sr ( و تغییرات Nd ἑ از 44/1+ تا 19/3 + همراه با تغییرات سیلیس، نشان‌گر تأثیر آشکار آلایش پوسته‌ای در تکوین ماگمای سازنده این سنگ‌هاست.

کلیدواژه‌ها

References
Ahmadian, J., Sarjoughian, F., Lentz, D., Esna-Ashari, A. and Murata, M., 2016- Eocene K-rich adakitic rocks in the Central Iran: Implications for evaluating its Cu–Au–Mo metallogenic potential. Ore Geology 72: 323-342.
Arvin, M., Pan, Y., Dargahi, S., Malekizadeh, A. and Babaei, A., 2007- Petrochemistry of the Siah-Kuh granitoid stock southwest of Kerman, Iran: implications for initiation of Neotethys subduction. Journal of Asian Earth Sciences 30: 474–489
Asadi, S., Moore, F. and Zarasvandi, A., 2014- Discriminating productive and barren porphyry copper deposits in the southeastern part of the central Iranian volcano-plutonic belt, Kerman region, Iran: a review. Earth-Science Reviews 138: 25–46.
Atherton, M. P. and Petford, N., 1993- Generation of sodium-rich magmas from newly underplated basaltic crust. Nature 362: 144–146
Azizi, H. and Jahangiri, A., 2008- Cretaceous subduction-related volcanism in the northern Sanandaj-Sirjan Zone, Iran. Journal of Geodynamics 45: 178–190.
Berberian, M. and King, G. C. P., 1981- Towards a palaeogeography and tectonic evolution of Iran. Canadian Journal of Earth Sciences 18: 210–265.
Brown, G. C., Thorpe, R. S. and Webb, P. C., 1984- The geochemical characteristics of granitoids in contrasting arcs and comments on magma sources. Journal of the Geological Society 141: 413–426.
Cameron, B. I., Walker, J. A., Carr, M. J., Patino, L. C., Matias, O. and Feigenson, M. D., 2003- Flux versus decompression melting at stratovolcanos in southeastern Guatemala. Journal of Volcanology and Geothermal Research 119: 21–50.
Chappell, B. J. and White, A. J. R., 1974 -Two Contrasting Granite Types, Pac. Geology 8: 173-174.
Defant, M. J. and Drummond, M. S., 1990- Derivation of some modern arc magmas by melting of young subducted lithosphere. Nature 347: 662–665.
Defant, M. J., Jackson, T. E., Drummond, M. S., De Boer, J. Z., Bellon, H., Feigenson, M. D., Maury, R. C. and Stewart, R. H., 1992- The geochemistry of young volcanism throughout western Panama and southeastern Costa Rica, an overview. Journal of the Geological Society 149: 569–579.
Delavari, M., Amini, S., Schmitt, A. K., McKeegan, K. D. and Harrison, T. M., 2014- U–Pb geochronology and geochemistry of Bibi-Maryam pluton, eastern Iran: implication for the late stage of the tectonic evolution of the Sistan Ocean. Lithos 200–201: 197–211.
Dimitrijevic, M. D., Cvetic, S. and Djokovic, I., 1973- Geology of Kerman region: institute for geological and mining exploration and institution of nuclear and other mineral raw materials, Scale: 1: 500000”, Geological survey of Iran, Report Yu/52, 334 pp.
Foley, S. F., Tiepolo, M. and Vannucci, R., 2002- Growth of early continental crust controlled by melting of amphibolite in subduction zones. Nature 417: 637–640.
Green, T. H., 1994- Experimental studies of trace element partitioning applicable to igneous petrogenesis Sedona 16 years later Chemical Geology 117: 1–36.
Guan, Q., Zhu, D. C., Zhao, Z. D., Dong, G. C., Zhang, L. L., Li, X. W., Liu, M., Mo, X. X., Liu, Y. S. and Yuan, H. L., 2012- Crustal thickening prior to 38 Ma in southern Tibet: evidence from lower crust-derived adakitic magmatism in the Gangdese Batholith. Gondwana Research 21: 88–99.
Harris, N. B. W., Pearce, J. A. and Tindle, A. G., 1986- Geochemical characteristics of collision-zone magmatism. In: Coward, M.P., Ries, A.C. (Eds.), Collision Tectonics, 19. Geological Society, London, Special Publications 19: 67–82.
Hastie, A. R., Kerr, A., McDonald, I., Mitchell, S. F., Pearce, J. A., Millar, I. L., Barfod, D. and Mark, D. F., 2010- Geochronology, geochemistry and petrogenesis of rhyodacite lavas in eastern Jamaica: A new adakite subgroup analogous to early Archaean continental crust? Chemical Geology 276: 344-359.
Hofmann, A. W., Jochum, K., Seufert, M. and White, M., 1986- Nb and Pb in oceanic basalts: new constraints on mantle evolution. Earth and Planetary Science Letters 79: 33–45.
Jahangiri, A., 2007- Post-collisional Miocene adakitic volcanism in NW Iran: geochemical and geodynamic implications. Journal of Asian Earth Sciences 30:433–447.
Jamshidi, K., Ghasemi, H. and Sadeghian, M., 2014- Petrology and geochemistry of the Sabzevar post-ophiolitic high silica adakitic rocks. Petrology 5:51-68.
Li, J., Zhao, X., Zhou, M., Ma, C. and Souza, Z., 2009- Late Mesozoic magmatism from the Daye region, eastern China: U–Pb ages, petrogenesis, and geodynamic implications. Contributions to Mineralogy and Petrology 157: 383-409.
Liu, S., Hu, R., Gao, S., Feng, Coulson, I., Feng, G., Qi, Y., Yang, Y., Yang, C. and Tang, L, 2012- U-Pb zircon age, geochemical and Sr-Nd isotopic data as constrains on the petrogenesis and emplacement time of the Precambrian mafic dyke swarms in the north china craton (NCC). Lithos140-141: 35- 52.
Ma, L., Jiang, S., Hou, M., Dai, B., Jiang, Y., Yang, T., Zhao, K., Wie, P., Zhu, Z. and Xu, B., 2014- Geochemistry of early Cretaceous calc-alkalin lamprophyres in the Jiaodong Peninsula: Implication for lithospheric evolution of the eastern North China craton. Gondwana research 25: 859-872.
Maniar, P. D. and Piccoli, P. M., 1989- Tectonic discrimination of granitoids. Geological Society of America Bulletin 101: 635-643.
Martin, H. and Moyen, J. F., 2003- Secular changes in TTG composition: comparison with modern adakites. EGS-AGU-EUG joint meeting, Nice, April, VGP7-1FR2O-001.
Middlemost, E. A. K., 1994- Naming materials in the magma/igneous rock system. Earth-Science Reviews 37: 215–224.
Omrani, J., Agard, P., Whitechurch, H., Benoit, M., Prouteau, G. and Jolivet, L., 2008- Arc magmatism and subduction history beneath the Zagros Mountains, Iran: a new report of adakites and geodynamic consequences. Lithos 106: 380–398.
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 25: 956-983.
Pearce, J. A. and Peate, D. W., 1995- Tectonic implications of the composition of volcanic arc magmas. Annual Review of Earth and Planetary Sciences 23: 251–285.
Peccerillo, A. and Taylor, S. R., 1976- Geochemistry of Eocene calk-alkaline volcanic rocks from the Kastamonu area, Northern Turkey. Contribution to mineralogy and petrology 58: 63-81.
Rapp, R. P., Watson, E. B. and Miller, C. F., 1995- Partial melting of amphibolite/eclogite and the origin of Archean trondhjemites and tonalities. Precambrian Research 51: 1–25.
Roberts, M. P. and Clemens, J. D., 1993- Origin of high-potassium, calcalkaline, I-type granitoids. Geology 21: 825–828.
Rollinson, H., 1993- Using Geochemical Data: Evaluation, Presentation, Interpretation. Longman Scientific and Technical, New York.
Shafiei, B., Haschke, M. and Shahabpour, J., 2009- Recycling of orogenic arc crust triggers porphyry Cu mineralization in Kerman Cenozoic arc rocks, southeastern Iran. Mineralium Deposita 44: 265–283.
Smith, E. I., Sanchez, A., Walker, J. D. and Wang, K., 1999- Geochemistry of mafic magmas in the Hurricane Volcanic field, Utah: implications for small- and large-scale chemical variability of the lithospheric mantle. The Journal of Geology  107: 433–448.
Stöcklin, J., 1968- Structural history and tectonics of Iran; a review. American Association of Petroleum Geologists Bulletin 52: 1229–1258.
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. and Norry, M. J.,eds., Magmatism in the ocean basins. Geological Society Special Publications 42: 313- 345.
Wolf, M. and Wyllie, P., 1994- Dehydration melting of solid amphibolite at 10 kb. The effect of temperature and time. Contrib. Mineralogy and Petrology 115: 369–383.
Zhao, J. H. and Zhou, M. F., 2008- Neoproterozoic adakitic plutons in the northern margin of the Yangtze Block, China: partial melting of a thickened lower crust and implications for secular crustal evolution. Lithos 104: 231–248.
Zindler, A. and Hart, S.R., 1986- Chemical geodynamics. Annual Review of Earth and Planetary Sciences 14: 493–571.