خاستگاه و دگرگونی‌های ماگمایی سنگ‌های خروجی قلیایی نوزا در منطقه نهبندان-آساگی، شرق ایران

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه سیستان و بلوچستان

2 دانشگاه میامی

چکیده

سنگ­های خروجی قلیایی نوزا در مناطق نهبندان و آساگی شامل بازانیت، هاوائیت، موژه­آریت و بنموریت هستند. در بازانیت­ها، مقادیر به نسبت کم Mg#، Ni و Cr بیانگر رخداد جدایش الیوین و کلینوپیروکسن از ماگمای اولیه سازنده آنهاست. همچنین در سنگ­های هاوائیت، موژه­آریت و بنموریت کاهش مقادیر CaO، TiO2، FeOt، عناصر خاکی نادر متوسط (MREE) و سنگین (HREE) با افزایش مقدار SiO2 نشان دهنده تاثیر فرایند جدایش کانی­های آمفیبول، کلینوپیروکسن و اکسیدهای آهن و تیتان بر تغییرات ترکیب آنهاست. در بازانیت­ها، هاوائیت­ها و موژه­آریت­های دارای کمتر از 52 درصد وزنی SiO2، مقدار بالای Nb/U و نبود ناهنجاری منفی Nb و Ta نشان از بی اثر بودن و یا اثر ناچیز فرایند آلایش پوسته­ای بر ترکیب این سنگ­ها دارد. ویژگی­های زمین شیمیایی و وجود بیگانه بلور­های کوارتز در سنگ­های جدایش یافته تر، مانند تعدادی از موژه­آریت­ها و بنموریت­ها، نشانگر اثر به نسبت بیشتر آلایش با پوسته قاره­ای است. مقادیر و نسبت­های عناصر کم مقدار در این سنگ­ها شبیه بازالت­های قلیایی جزایر اقیانوسی (OIB) است. مقدار نسبت­های N(Tb/Yb) بیش از 80/1 و N(Dy/Yb) بیش از 60/1 در این سنگ­ها نیز بیانگر ناشی شدن ماگماهای سازنده آنها از یک گوشته سست کره­ای در عمق پایداری کانی گارنت است. همچنین، مدل سازی ذوب­بخشی نشان می­دهد که ماگمای سازنده بازانیت­ها برآمده از 5 تا 7 درصد ذوب­بخشی و برای سایر نمونه­ها از 2 درصد ذوب بخشی یک خاستگاه گارنت لرزولیتی است.    

کلیدواژه‌ها

عنوان مقاله [English]

Origin and magmatic evolution of the alkaline extrusive rocks of Neogene from Nehbandan-Assagie region, eastern Iran

نویسندگان [English]

  • Neda Mokhtari 1
  • Ali Ahmadi 1
  • hasan Mirnejad 2
1
2
چکیده [English]

The alkaline extrusive rocks of Neogene from Nehbandan-Assagie region, eastern Iran, include basanite, hawaiite, mugearite and benmoreite. Relatively low Ni and Cr contents and Mg-numbers of basanites are indicative of olivine and clinopyroxene fractionation from their relevant primary magma. Decreasing of CaO, TiO2, FeOt, HREEs and MREEs with increasing SiO2 indicate fractional crystallization of amphibole, clinopyroxene and Fe-Ti oxides. In basanites, hawaiites and mugearites with less than 52 wt.% of SiO2, high Nb/U ratio and lack of Nb and Ta negative anomalies are evidence for the low effect of crustal assimilation, if any, to the chemical composition of these rocks. In more-fractionated rocks, like some mugearites and benmoreites, crustal contamination is inferred from chemical characteristics and existence of quartz xenocrysts. The trace element concentrations and ratios of these rocks are similar to those of alkaline oceanic island basalts (OIB). (Tb/Yb)N more than 1.80 and (Dy/Yb)N more than 1.60 of these rocks are considered here as their generation after partial melting of an asthenospheric mantle in the garnet stability field. In addition, geochemical differences between the basanites and the other rocks are due to formation of their magmas, respectively, after 5-7 percent and 2 percent partial melting of a garnet lherzolite source.

کلیدواژه‌ها [English]

  • alkaline
  • basanite
  • hawaiite
  • mugearite
  • benmoreite
  • Sistan suture Zone

مراجع

[1] Tirrul L., Bell I. R., Griffis R. J., Camp V. E., "Sistan suture zone of eastern Iran", Geological Society of America Bulletin 94 (1983) 134-150.

[2] Pang K. N., Chung S. L., Zarrinkoub M. H., Khatib M. M., Mohammadi S. S., Chiu H. Y., Chu C. H., Lee H. Y., Lo C. H., "Eocene–Oligocene post-collisional magmatism in the Lut–Sistan region, eastern Iran: Magma genesis and tectonic implications", Lithos 180-181 (2013) 234-251.

[3] Alavi Naini M., Lotfi M., " Geological Map of Nehbandan, scale 1:100000", Geological Survey of Iran (1989).

[4] Alavi Naini M., Lotfi M., " Geological Map of Khunik, scale 1:100000", Geological Survey of Iran (1990).

[5] Alavi Naini M., Lotfi M., " Geological Map of Seyasteragi, scale 1:100000", Geological Survey of Iran (1991).

[6] Biabangard H., Najafzade M., "Mineralogy, geochemistry and origin of Chaharfarsakh intrusive and extrusive rocks, Lut block", Iranian Journal of Crystallography and Mineralogy 24 (2016) 515-530 (in Persian, with English abstract).

[7] Camp V. E., Griffis R. J., "Character, genesis and tectonic setting of igneous rocks in the Sistan Suture Zone, of eastern Iran", Lithos 15 (1982) 221-239.

[8] Walker R. T., Gans P., Allen M. B., Jackson J., Khatib M., Marsh N., Zarrinkoub M., "Late Cenozoic volcanism and rates of active faulting in eastern Iran", Geophysical Journal International 177 (2009) 783–805.

[9] Mollashahi N., Zarrinkoub M. H., Mohammadi S. S., Khatib M. M., " Petrology of young volcanics in Hamun Lake Area (East of Iran)", Iranian Journal of Crystallography and Mineralogy 19 (2011) 519-528 (in Persian, with English abstract).

[10] Pang K. N., Chung S. L., Zarrinkoub M. H., Mohammadi S. S., Yang H. M., Chu C. H., Lee H. Y., Lo C. H., "Age, geochemical characteristics and petrogenesis of late Cenozoic intraplate alkali basalts in the Lut–Sistan region, eastern Iran", Chemical Geology 306-307 (2012) 35-40.

[11] Kheirkhah M., Neill M.I., Allen M.B., " Petrogenesis of OIB-like basaltic volcanic rocks in a continental collision zone: Late Cenozoic magmatism of Eastern Iran", Journal of Asian Earth Sciences 106 (2015) 19–33.

[12] Mojadadi moghadam H., Ahmadi A., "Petrology and geochemistry of pillow lavas and mafic rocks in the middle part of the fault zone Nosratabad-Kahurak, East of Iran", Iranian Journal of Crystallography and Mineralogy 23 (2015) 309-320 (in Persian, with English abstract).

[13] Khatib M., "Geometry of strike-slip Fault termination", PhD thesis, Shahid Beheshti University (1377) (in Persian).

[14] Walker R. T., Jackson J., "Active tectonics and late Cenozoic strain distribution in central and eastern Iran", Tectonics 23 (2004).

[15] Nazari H., Salamati R., "Geological Map of Sarbisheh, scale 1:100000", Geological Survey of Iran (1999).

[16] Whitney D. L., Evans B. W., "Abbreviations for names of rock-forming minerals", American Mineralogist 95 (2010) 185–187.

[17] Dunn T., Stringer P.,"Petrology and petrogenesis of the Ministers Island dike, southwest New Brunswick, Canada", Contributions to Mineralogy and Petrology 105 (1990) 55-65.

[18] Jeffrey P.G., " Chemical Methods of Rock Analysis". 2nd edition, Pergamon Press, Oxford, England (1975).

[19] Le Maitre R.W., "Igneous Rocks, a Classification and Glossary of Terms", Cambridge University Press, New York (2002) 236 p.

[20] Williams H., Turner F. J., Gilbert C. M., "Petrography; An Introduction to the Study of Rocks in Thin Sections", W. H. Freeman and Company, New York, (1982) 606p.

[21] Farmer G. L., "Continental Basaltic Rocks", University of Colorado, Boulder, Co, USA (2007).

[22] Esmaeily D., Valizadeh M.V., Noorolahi Z., Kananian A., " Mineral chemistry and whole rock geochemistry evidences of the differentiation in the Karaj Dam basement igneous rocks", Iranian Journal of Crystallography and Mineralogy 1 (2006) 153-176 (in Persian, with English abstract).

[23] Macdonald G. A., "Composition and origin of Hawaiian lavas", Geologyical Society of American Memoir 116 (1968) 477-522.

[24] Sun S. S., McDonough W. F., “A chemical and isotopic systematics of oceanic basalts Implication for mantle composition and processes",In: Saunders A. D., Norry M. J., (eds), Magmatism inoceanic basins, Geologyical Society, of London Special Publication 42(1989) 313–345.

[25] Le Bas M. J., "IUGS reclassification of the high-Mg and picritic volcanic rocks",Journal of Petrology 41 (2000) 1467–1470.

[26] White W. M., " Geochemistry", First edition, Wiley- Blackwell, Chichester (2013).

[27] Yang J. H., Wu F.Y., Wilde S.A., Chen F., Liu X.M., Xie L.W., "Petrogenesis of an Alkali Syenite-Granite-Rhyolite Suite in theYanshan Fold and Thrust Belt, Eastern North China Craton: Geochronological, Geochemical and Nd-Sr-Hf Isotopic Evidence for Lithospheric Thinning",Journal of Petrology 49 (2008) 315-351.

[28] Wilson M., "Igneous Petrogenesis; A Global Tectonic Approach", Chapman and Hall (1989).

[29] Haghnazar Sh., Malakotian S., " The role of fractional crystallization and crustal contamination in the magmatic evolution of Paleogene volcanic rocks of Damash area in Guilan Province", Iranian Journal of Crystallography and Mineralogy 20 (2013) 651-662 (in Persian, with English abstract).

[30] Cox K. G., "A model for flood basalt volcanism", Journal of Petrology 21 (1980) 629-650.

[31] Aldanmaz E., Pearce J.A., Thirlwall M.F., Mitchell J.G., " Petrogenetic evolution of late Cenozoic, post-collision volcanism in western Anatolia, Turkey", Journal of Volcanology and Geothermal Research 102 (2000) 67–95.

[32] Harangi S., Downes H., Thirlwall M., Gmeling K., " Geochemistry, Petrogenesis and Geodynamic Relationships of Miocene Calc-alkalineVolcanic Rocks in theWestern Carpathian Arc, Eastern Central Europe", Journal of Petrology 48 (2007) 2261-2287.

[33] Bachmann O., Dungan M., Bussy F., "Insights into shallow magmatic processes in large silicic magma bodies: the trace element record in the Fish Canyon magma body, Colorado", Contributions to Mineralogy and Petrology 149 (2005) 338–349

[34] Yang J.H., Sun J.F., Zhang M., Wu F.Y., Wilde S.A., " Petrogenesis of silica-saturated and silica-undersaturatedsyenites in the northern North China Craton related to post-collisional and intraplate extension", Chemical Geology 328 (2012) 149–167.

[35] Macdonald R., Belkin H. E., Fitton J. G., Rogers N.W., Nejbert K., Tindle A. G., Marshall A. S., " The Roles of Fractional Crystallization, Magma Mixing, Crystal Mush Remobilization and Volatile Melt Interactions in the Genesis of a Young Basalt Peralkaline Rhyolite Suite, the Greater Olkaria Volcanic Complex, Kenya Rift Valley", Journal of Petrology 40 (2008) 1515-1547.

[36] Pearce J.A., Peate D.W., " Tectonic implications of the composition of volcanic arc magmas", Annual Reviews of Earth and Planetary Sciences 23 (1995) 251–285.

[37] Reichew M. K., Saunders A. D., White R. V., Ukhamedov, A. I., " Geochemistry and Petrogenesis of Basalts from the West Sibrian Basin: an extention of the Permo-Triassic Sibrian Traps, Russia", Lithos 79 (2004) 425-452.

[38] Neal C.R., Mahoney J.J., Chazey W.J., "Mantle sources and the highly variable role of continental lithosphere in basalt petrogenesis of the Kergulen Plateau and Broken Ridge LIP: results from ODP Leg 183", Journal of Petrology 43 (2002) 1177–1205.

[39] Pearce J.A., "Geochemical fingerprinting of oceanic basalts with applications to ophiolite classification and the search for Archean oceanic crust", Lithos 100 (2008) 14-48.

[40] Hofmann A., Jochum K., Seufert M., White M., "Nb and Pb in oceanic basalts: New constraints on mantle evolution", Earth and Planetary Science Letters 79 (1986) 33–45.

[41] Green T.H., "Significance of Nb/Ta as an indicator of geochemical processes in the crust - mantle system", Chemical Geology 120 (1995) 347-359.

[42] Wang K., Plank T., Walker J.D., Smith E.I., " A mantle melting profile across the Basin and Range. SW USA", Journal of Geophysical Research-Solid Earth 107 (2002).

[43] Xu Y. G., Ma J. L., Frey F. A., Feigenson M. D., Liu J. F., "Role of lithosphere– asthenosphere interaction in the genesis of Quaternary alkali and tholeiitic basalts from Datong, western North China Craton", Chemical Geology Including Isotope Geoscience 224 (2005) 247– 271.

[44] Albarede F., " Introduction to Geochemical Modeling", Cambridge University Press, New York (1996).

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سابقه مقاله

  • تاریخ دریافت: 30 اردیبهشت 1398
  • تاریخ بازنگری: 03 مرداد 1398
  • تاریخ پذیرش: 02 شهریور 1398

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