بررسی ژئوشیمی و خاستگاه سنگ های آتشفشانی کواترنری منطقه شرق اهر (شمال غرب ایران )

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه زمین شناسی، دانشگاه پیام نور، تهران ، ایران

چکیده
سنگ های آتشفشانی  شرق اهر  با ساختمان های متنوع بر روی واحدهای آذرآواری پلیوپلیستوسن و نهشته های آبرفتی جوان قرار گرفته‌اند. این سنگ ها با ماهیت بازالت- تراکی بازالت، بازالت آندزیتی و  تراکیت،  با بافت میکرولیتیک پورفیری، هیالو میکرولیتیک و پورفیری حفره­دار در منطقه رخنمون دارند.  بررسی داده­ های ژئوشیمیایی دال بر ماهیت قلیایی نمونه‌ها می باشد که در یک محیط زمین ساختی  قوس آتشفشانی پس از برخورد تشکیل شده‌اند. الگوی پراکندگی عناصر نادر خاکی دال بر غنی شدگی از عناصر نادر خاکی سبک و تهی شدگی از عناصر نادر خاکی سنگین می باشد. این نمونهها دارای آنومالی منفی  NbوNb,P,Ti, Zr  و آنومالی مثبتCs, Rb, Pb, Ba, U ،La ،Th وLILE  می باشد.  در نمودار تعیین موقعیت تکتونیکی، این سنگ ها در گستره OIB قرار می‌گیرند. این الگوی غنی­شدگی و تهی­ شدگی از عناصر نادر خاکی با خاستگاه گوشته استنوسفری تطابق دارد. تلفیق داده ­های ژئوشیمیایی نشان می­دهد که سنگ های اتشفشانی شرق اهر، در موقعیت کششی کمان های پس از برخورد در حاشیه فعال قاره ای در ارتباط با شکستگی­ ها و گسل های امتدادلغز تشکیل شده ­اند .

کلیدواژه‌ها

موضوعات


عنوان مقاله English

Study of Geochemistry and Quaternary Volcanic Rocks source, East of Ahar (NW Iran)

نویسندگان English

Shohreh Hasanpour
Maryam Ahankoob
Department of Geology, Payam Noor University, Tehran, Iran
چکیده English

1. Introduction
Azerbaijan Plateau is a part of the Alpine-Himalayan fold and orogeny belt, which is located in a compressional regime and between Talesh Mountains, south of Lesser Caucasus Mountain, east of Anatolia, north of Zagros Mountain. The studied area has located in the geographical longitudes of 47° to 48° and latitudes of 38° to 39° in East Azerbaijan province. There are wide ranges of Plio-Quaternary basalts and andesite basaltic in the sheet of 1.250000 Ahar. These rocks are gray to black in color. They also are formed of lava flows with scattered sometimes prismatic structures on the Paleocene andesitic lavas or conglomerate, siltstone and red marl Pliocene.
2. Materials and methods
    After the field investigations, we were taken 30 fresh and unaltered samples. Then, they were prepared as a thin section, then go undrer petrographic studies with a microscope in the laboratory.  Finally, we selected 10 samples were sent to the Amdel laboratory in the Australia for chemical analyses by ICP-MS, and OES.  Consequently, the results of whole rock chemical analysis data, were processed by GCD-KIT software. Then, all data were interpreted by geochemical conditions of all analyzed samples and also with their tectonic environment in the area.
3. Results and Discussion
The studied area is a part of the lesser Caucasus mountain range with high deformation and seismicity, which has located in a crustal convergence in the northwest of Iran. This area has a faulted system and with active strike-slip faults (Kocyigit et al., 2001). These systems often coincided with previous crustal discontinuities and have been widely effective in generating Quaternary magmatic activities locally through pull-part zones (Shabanian et al., 2012; Avagayan et al., 2010). Almost all the Quaternary magmatism in the region has occurred due to the operation of these fault systems and in the tensile position of the continental crust. Therefore, active fracture and fault systems and even old hidden faults have played a major role in the occurrence of the Quaternary magmatism.
Volcanic rocks of the studied area are hyalo-aphanitic to hyalo-microlithic porphyry texture with large crystals of olivine, plagioclase and pyroxene. Also, porphyry, trachyte, intersertal and intergranular texture can be seen in these samples. These samples have the nature of basaltic, thrachy andesite, mojearite and dacite, which are located in a calc-alkaline range. These rocks are rich in LREE and depleted in HREE.
They also have enriched of Cs, Th, Pb and depletion of Ba, Nb, Eu, La. The presence of garnet in the source of magma can indicated the involvement of processes and crystallization of olivine, pyroxene, and plagioclase. In addition, metasomatism or contamination with enriched crustal materials (Menzies & Wass, 1983) leads to the abundance of LREE elements. Therefore, the metasomatized mantle can be a suitable origin for the magma of the studied volcanic rocks. Enrichment of elements Cs, Rb, Pb, Ba, LILE and depletion of elements HFSE (Nb, Zr) indicated the magma of subduction arc zones (Wilson, 1989). The negative anomaly of Nb, P, Ti, Zr and the positive anomaly of Pb are the characteristics of crust contamination of quaternary basalts (Wilson, 1989; Hofman, 1997). Negative Nb anomaly is characteristic of continental rocks and crustal involvement in magmatic processes (Hofman, 1997). Also, the negative anomaly of Ti and Nb in the normalized pattern with primary mantle composition can indicate magmas related to subduction (Pearce, 1983; Wilson, 1989). All the samples are in the range of intraplate basalts (Figure a10) (Mesched, 1986), and show the orogenic situation (Pearce et al., 1977). The studied volcanic samples are volcanic arc (Muller et al., 1992) belong to the continental arc after the collision (Groves, 1997).  Also, the studied samples show the origin of lherzolite garnet mantle and lherzolite spinel with a rate of 2 to 5% of partial melting.
The tensile positions of the continental margins are active, where partial melting has occurred due to pressure reduction and rupture of the subcontinental lithosphere. Its compressive force resulting from crustal collision and crustal shortening, thickening and uplift leads to disturbance of subcontinental lithosphere thermal levels in these regions. Therefore, it seems that since the Eocene, the post-collision regime (Omrani et al., 2008) and since the Miocene (Hasanpour, 2008) has been ruling in the Arsbaran.
4. Conclusion
The Quaternary volcanic rocks in the eastern part of Ahar area, include a set of basaltic, andesite basaltic and andesite with calc-alkaline nature. The special depletion and enrichment of rare earth elements, these rocks are very similar to enriched mantle magmas and OIB, which were formed in the volcanic arc environment after impact on the active continental margin. For these samples, the mantle origin is lherzolite garnet to lherzolite spinel with 1 to 10% partial melting. Also there were happened metasomatisms of subducting oceanic lithosphere fluids. The geochemical evidences show some degrees of crustal contaminations during magma ascent. This magmatism has occured due to the subduction and the system of faults and fractures of the region and the tension tectonic situation. This tension system in the active continental margin after the collision has led to a decrease in pressure and finally the pouring out of basaltic magma.

کلیدواژه‌ها English

Volcanic rocks
volcanic arc
active continental margin
landslide faults
Quaternery
Ahar
تاج بخش، غ.، امامی ، م.، معین وزیری، ح.،  رشید نژاد، ن.،(1391)، بررسی سنگ‌شناسی، ژئوشیمی و جایگاه زمین‌ساختی توده نفوذی کلیبر (آذربایجان شرقی) . مجله علوم زمین ، شماره 85 ، صص 205 تا 2.
حسن­پور، ش.، 1389، متالوژنی مس و طلا در زون ارسباران، شمال غرب ایران، رساله دکتری، دانشگاه شهیدبهشتی، تهران، ایران متشر نشده.
جوادی تازه کند، ح.، موید، محسن.، جهانگیری ، احمد.، حسین زاده، محمد.رضا.، رحمانی، ا.، و روان خواه، ع.ر.، (1400). ژئوشیمی و جایگاه زمین ساختی توده های نفوذی کلاسور ( غرب کلیبر- شمال غرب ایران). پژوهشهای دانش زمین ،صص 124-139.
چراغی، آ،. اهنگری، معصومخ.، اسدپور، م.،(1399)، شیمی کانی کلینو پیروکسن های موجود در بازالتهای جنوب غرب خوی، شمال غرب ایران: تعین محیط زمین ساختی و شرایط تشکیل سنگ های بازالتی، مجله بلورشناسی و کانی شناسی  ایران، دوره 28 ، (2)،صص 401-414.
حسین زاده، ز ، شیخ بگلو ، ص( 1395) ، تحلیل رژیم های تنش در پهنه اذربایجان ، شمال باختر ایران ف یافته های نوین زمین شناسی کاربردی ، دوره 10 ، شماره 20.
درویش زاده، علی.، (1372)، زمین شناسی ایران انتشارات نشر دانش امروز 440.
رحمانی، ا.، حسین‌زاده، م.ح.، جهانگیری، ا.، مؤید، م.، جوادی تازه کند، ح.، روان خواه، ا.، (1400)، ژئوشیمی و جایگاه زمین ساختی تودههای نفوذی کلاسور(غرب کلیبر- شمالغرب ایران) ، پژوهشهای دانش زمین، شماره 46، صص 124-1.
سیاهکالی مرادی، ع.، تاتار، م.، هاتسفلد، د. و پل، آ.، (1387)، مطالعه ساختار سرعتی پوسته و سازوکار گسلش در زون گسلی امتدادلغز تبریز: علوم زمین، دوره 70، صص 153-140.
قاسمی برقی، ا، (1384)، پترولوژی و ژئوشیمی ولکانیکهای ائوسن شمال باختری مشگین شهر، تز دکتری، دانشگاه شهید بهشتی.
عامل، نصیر.، موید، محسن.، عامری،.علی.، وثوقی عابدینی، م.، موذن، محسن.،(1387)، سنگ زایی بازالتهای پلیو- کواترنری آذربایجان و مقایسه آنها با بازالتهای مشابه در شرق ترکیه، مجله بلورشناسی و کانی شناسی، صص327-340.
مؤید، محسن.،(1380)، بررسیهای پترولوژیکی نوار ولکانو پلوتونیک ترشیاری البرز غربی آذزبایجان با نگرشی ویژه بر منطقه هشتچین، تز دکترا. گرایش پترولوژی، دانشکده غلوم دانشگاه شهید بهشتی.
معین وزیری ، حسین.، (1382)، چند نقطه عطف در تاریخچه تکتونوماگمایی ایران، نشریه علوم زمین، دوره 11،صص  32-39.
عامل، نصیر.، اکبرزاده، لاله (1395) بررسی زمین‌شیمی بازالت‌های جوان آذربایجان‌شرقی (شمال‌باختری ایران). دوره 7،  شماره 28،  109-126
Abdel -Fattah, M., Abdel -Rahman, A. M. and Nassar, P. E. (2004) Cenozoic volcanism in the Middle East: Petrogenesis of alkali basalts from Northern Lebanon. Geological Magazine 141: 545 -63.
Abdel-Rahman, A. F. M., & Nassar, P. E. (2004). Cenozoic volcanism in the Middle East: petrogenesis of alkali basalts from northern Lebanon. Geological magazine, 141(5), 545-563.
Ahmadzadeh, G. R. (2010) Petrological studies of volcanic rocks from Northwest of Marand with spatial focus on alkaline rocks. Ph. D. thesis, University of Tabriz, Tabriz, Iran (in Persian).
Allmendinger, R. W., Jordan, T. E., Kay, S. M., & Isacks, B. L. (1997). The evolution of the Altiplano-Puna plateau of the Central Andes. Annual review of earth and planetary sciences, 25(1), 139-174.
Ambraseys، N.N.، (1997). The Krasnovodsk (Turkmenistan) earthquake of 8 July 1895، J. Earthquake Eng.، 1، 293–317.
Avagyan, A., Sosson, M., Karakhanian, A., Philip, H,. Rolland, Y., Melkonhyan, R., Davtyan. Y., (2010), Recent stress field evolution in the Lesser Caucasus and adjacent regions, In: Sosson, M., Kaymakci, N., Stephenson, R., Bergerat, F., Starostenko, V. (Eds.), Sedimentary Basin Tectonics from the Black Sea and Caucasus to the Arabian Platform Geol. Soc. London, Spec. Publ., 340 (2010), pp. 393-409.
Axen، G.J.، Lam، P.S.، Grove، M. & Stockli، D.F.، (2001), Exhumation of the west-central Alborz mountains، Iran، Caspian subsidence، and collision-related tectonics، Geology، 29، 559–562.
Aydin, F., Karsli, O. and Chen, B. (2008) Petrogenesis of the Neogene Alkaline Volcanics with Implications for Post-Collisional Lithospheric Thinning of the Eastern Pontides, NE Turkey. Lithos, 104, 249-266.Baker، C.، 1993. The active seismicity and tectonics of Iran. PhD thesis، University of Cambridge، UK.
Barker, A. J., Menzies, M. A., Thirlwall, M. F. & Macpherson, C. G.,(1997) Petrogenesis of Quaternary intrplate volcanism, Sana,a, Yemen: Implications for plume-lithosphere interaction and polybaric melt hybridization. Journal of petrology 38: 1359-1390.
Berberian, M., (1976). Contribution to the Seismotectonics of Iran, Part II. Geol. Surv. Iran, 39, 518p (in English) with five color maps.
Berberian, M., & R. S. Yeats (1999), Patterns of historical earthquake rupture in the Iranian Plateau, Bull. Seismol. Soc. Am., 89(1), 120–139.
Best, M. G., Barr, D. L., Christiansen, E. H., Gromme, S., Deino, A. L., & Tingey, D. G. (2009). The Great Basin Altiplano during the middle Cenozoic ignimbrite flareup: Insights from volcanic rocks. International Geology Review, 51(7-8), 589-633.
Boynton, W.V. (1984) Geochemistry of Rare Earth Elements: Meteorite Studies. In: Henderson, P., Ed., Rare Earth Element Geochemistry, Elsevier, New York, 63-114.
Cooply, A & Jackson, J., (2006). Active tectonics of the Turkish-Iranian Plateau. Tectonics, v, 25, TC6006.
Cox, K.G., et al. (1979). The Interpretation of Igneous Rocks. Allen and Unwin, London, 450 p.                                    
Fitton, J. G., James, D., Kempton, P. D., Ormerod, D. S., & Leeman, W. P. (1988). The role of lithospheric mantle in the generation of late Cenozoic basic magmas in the western United States. Journal of Petrology, (1), 331-349.
Fitton, J. G., James, D., Kempton, P. D., Ormerod, D. S. & Leeman, W. P. (1988) The role of lithospheric mantle in the generation of late Cenozoic basic magmas in the western United States, In: Oceanic continental lithosphere: Similarities and differences (Eds. Cox, K. G. and Menzies, M. A.) Special Lithosphere issue 223 -352. Journal of Petrology.
 
Frey, F.A., Jones, W.B., Davies, H., & Weis, D., (1991). Geochemical and petrologic data for basalts from Site 756, 757, and 758: implications for the origin and evolution of Ninetyeast Ridge. Proc. ODP Sci. Results 121, 611–659.
Furman, T., & Graham, D. (1999). Erosion of lithospheric mantle beneath the East African Rift system: geochemical evidence from the Kivu volcanic province. In Developments in Geotectonics (Vol. 24, pp. 237-262). Elsevier.
Green, N. L. (2006) Influence of slab thermal structure on basalt source regions and melting conditions: REE and HFSE constraints from Garibaldi volcanic belt, northern Cascadia subduction system. Lithos 87: 23-49.
Hafkenscheid, E., Wortel, M. J. R., Spakman, and W.Harker A (1909) The natural history of igneous rocks. Macmillan, New York.
Hessami, D., Pantosti, H., Tabassi, E., & K, Feghhi., Shabanian, M.,  Abbassi, R., Feghhi, K., and Solaymani, S. 2003. Paleoearthquales and slip rates of the North, Tabriz Fault, NW Iran: Preliminary result. Annals of Geophysics, 46.5.
Hofmann, A. W. 1997, Mantle geochemistry: the message from oceanic volcanism, Nature volume 385, 219–229.
Ilnicki, S. (2010) Petrogenesis of continental mafic dykes from the Izere complex Krakonosze -Izra Block (West Sudetes, SW Poland). International Journal of Earth Sciences 99: 745 -773.
 
Innocenti, F., Mazzuoli, R., Pasquare, G., Radicati di Brozolo, F., & Villari, L. (1982). Tertiary and quaternary volcanism of the Erzurumkars area (Eastern Turkey): geochronological data and geodynamic evolution. Journal of Volcanology and Geothermal Research, 13(3), 223-240.
Irvine, T.N. and Baragar, W.R.A. (1971) A Guide to the Chemical Classification of the Common Volcanic Rocks. Canadian Journal of Earth Science, 8, 523-548.
Jackson,,J. A., (1992). Partitioning of strike-slip and convergent motion between Eurasia and Arabia in eastern Turkey and aucasus. Journal of Geophysics. 97. 12471-12479.
Keskin, M. (2003). Magma generation by slab steepening and breakoff beneath a subductionaccretion complex: An alternative model for collisionrelated volcanism in Eastern Anatolia, Turkey. Geophysical Research Letters, 30(24).
Koçyiğit, A & Erol, O., (2001), A tectonic escape structure: Erciyes pull-apart basin, Kayseri, central Anatolia, Turkey, 14.
Lightfoot, P. C., & Keays, R. R. (2005). Siderophile and chalcophile metal variations in flood basalts from the Siberian trap, Noril’sk region: Implications for the origin of the Ni-Cu-PGE sulfide ores. Economic Geology, 100(3), 439-462.
Maggi, A. & Priestley, K. (2005) Surface Waveform Tomography of Turkish-Iranian Plateau. Geophysical Journal International, 160, 1068-1080.
Masson، F.، Martinod، J.، Hatzfeld، D.، Vernant، P.، Tavakoli، F., & Ashtiani، A.، (2005) SeismicVersus aseismic deformation in Iran inferred from GPS and Seismicity data. Geophyse. J. Int. 160، 217-226.
McClusky, S., Bassalanian, C., Barka, A., Demir, C., Ergintav, S., Georgiev, I., Gurkan, O.,Hamburger, M., Hurst, K., Hans-Gert, H.-G., Karstens, K., Kekelidze, G., King, R., Kotzev, V., Lenk, O., Mahmoud, S., Mishin, A., Nadariya, M., Ouzounis, A., Paradissis, D., Peter, Y., Prilepin, M., Relinger, R., Sanli, I. Seeger, H., Tealeb, A., Toksaz, M. N. & Veis, G., (2000), Global Positioning system constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus: J. Geophys. Res., 105 (B3), 5695-5719.
McKenzie, D. A. N., & O'NIONS, R. K. (1995). The source regions of ocean island basalts. Journal of petrology, 36(1), 133-159.
Menzies, M. A., & Wass, S. Y. (1983). CO2-and LREE-rich mantle below eastern Australia: a REE and isotopic study of alkaline magmas and apatite-rich mantle xenoliths from the Southern Highlands Province, Australia. Earth and Planetary Science Letters, 65(2), 287-302.
Meschede, M. (1986) A Method of Discrimination between Different Types of Mid-Ocean Ridge Basalts and Continental Tholeiites with the Nb-Zr-Y Diagram. Chemical Geology, 56, 207-218.
Muller, D. & Groves, D.I., (1997), Potassici igneous rocks and associated gold-copper mineralization: Lecture Notes in Earth Sciences, No.56, 238pp.
Nabavi, M.H. (1976) A Preface to Iran’s Geology. Geology Survey & Mineral Exploration of Iran, 109.
Omrani, J, Agard, Ph., Whitechurch, H., Benoit, M., Prouteau, G., & Jolivet, L., (2008), Arc-magmatism and subduction history beneath the Zagros Mountains, Iran: a new report of adakites and geodynamic consequences, Lithos, 3: 380-398.
Pearce, D., & Turner, R. K. (1990). Economics of natural resources and the environment. Baltimore: Johns Hopkins University Press.
Pearce, J. A. (1996) A users guide to basalt discrimination diagrams. Trace Element Geochemistry of Volcanic Rocks: Applications for Massive Sulphide Exploration. Geological Association of Canada, Short Course Notes 12: 79 -113.
Pearce, J. A., Bender, J. F., De Long, S. E., Kidd, W. S. F., Low, P. J., Güner, Y., ... & Mitchell, J. G. (1990). Genesis of collision volcanism in Eastern Anatolia, Turkey. Journal of Volcanology and Geothermal Research, 44(1-2), 189-229.
Pearce, J. A. (1983). Role of the sub-continental lithosphere in magma genesis at active continental margins.
Pearce, J.A. (2008) Geochemical Fingerprinting of Oceanic Basalts with Applications to Ophiolite Classification and the Search for Archean Oceanic Crust. Lithos, 100, 14-48.
Rudnick, R. L., Gao, S., Holland, H. D., & Turekian, K. K. (2003). Composition of the continental crust. The crust, 3, 1-64.
Salters, V., Longhi, J.E. & Bizimis, M. (2002) Near mantle solidus trace element partitioning at 1664 pressures up to 3.4 GPa. Geochem. Geophys. Geosys. 3, 1-23.
Saunders, A. D., Norry, M. J. & Tarney, J. (1991) Fluid influence on the element composition of subduction zone magmas. Philosophical Transactions of the Royal Society of London, Series A, 35: 371 -392.
Schandl, E. S. & Gorton, M. P. (2002) Application of high field strength elements to discriminate tectonic settings in VMS environments. Economic Geology 97: 629 -642.
Shabanian, E., Acocella, V., Gioncada, A., Ghasemi, H., & Bellier, O. (2012). Structural control on volcanism in intraplate post collisional settings: Late Cenozoic to Quaternary examples of Iran and Eastern Turkey. Tectonics, 31(3).
Shabanian, N., Davoudian, A.R., Dong, Y., & Liu, X.,(2018), U-Pb zircon dating, geochemistry and Sr-Nd-Pb isotopic ratios from Azna-Dorud Cadomian metagranites, Sanandaj-Sirjan zone of western Iran. Precambrian Research 306, 41-60
Sun, S.S. & 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 the Ocean Basins, Geological Society, London, Special Publications, 42, 313-345. 
Turner, S., Arnaud, N., Liu, J., Rogers, N., Hawkesworth, C., Harris, N., Kelley, S., Van Calsteren,P., & Deng, W., (1996), Post-collision, shoshonitic volcanism on the Tibetan plateau: Implications for convective thinning of the lithosphere and the source of ocean island basalts: Journal of Petrology, v. 37, p. 45–71, doi:10.1093/ petrology/37.1.45.
Willson, M. (1989) Igneous petrogenesis: a global tectonic approach. Unwin Hymen, London .
 Wilson, M. & Downes, H. (2006) Tertiary – Quaternary intraplate magmatism in Europe and its relationship to mantle dynamics. Geological Society of London 32(3): 147 -166.

Yan, J., & Zhao, J. X. (2008). Cenozoic alkali basalts from Jingpohu, NE China: the role of lithosphere–asthenosphere interaction. Journal of Asian Earth Sciences, 33(1-2), 106-121.

Ying, J.,  Zhang, H., Sun, M., Tang, Y.,  Zhou, X., & Liu, X., (2007) Elsevier. Petrology and geochemistry of Zijinshan alkaline intrusive complex in Shanxi Province, western North China Craton: Implication for magma mixing of different sources … Lithos.45-66.
Zor, E. (2008). Tomographic evidence of slab detachment beneath eastern Turkey and the Caucasus. Geophysical Journal International, 175(3), 1273-1282.