مطالعه شیمی کانی ها و فابریک‌های ماگمایی- تکتونیکی دایک‌های پگماتوئیدی، جنوب خاور همدان

نویسندگان

1 استادیار گروه زمین‌شناسی، دانشکده علوم‌پایه، دانشگاه بوعلی‌سینا، همدان، ایران

2 دانشیار گروه زمین‌شناسی، دانشکده علوم‌پایه، دانشگاه بوعلی‌سینا، همدان، ایران

چکیده

در جنوب خاور همدان دایک‌های پگماتوئیدی فراوانی به درون شیست‌ها نفوذ کرده‌اند. این دایک‌ها دارای ترکیب کانی‌شناسی شامل آلبیت، فلدسپار آلکالن، تورمالین، کوارتز و مسکویت است. مطالعه بر روی نحوه نفوذ دایک‌ها به درون شیست‌ها، تشخیص انواع مختلف دایک‌ها بر اساس خصوصیات میکروسکوپی و بررسی تعامل آن­ها با سنگ ‌میزبان، از اهداف کلیدی این تحقیق بوده و نتایج آن می‌تواند به درک عمیق‌تری از عوامل مؤثر در شکل‌گیری دایک‌های پگماتوئیدی و تأثیرات آن­ها بر روی زمین‌شناسی منطقه منجر شود. براساس آنالیز نقطه‌ای تورمالین‌ها از نوع شورلیت، فلدسپارها از نوع ارتوکلاز، پلاژیوکلاز‌ها از نوع آلبیت و مسکویت‌ها عضو انتهایی مسکویت- سلادونیت هستند. با توجه به مقدار Fe# در برابر اکسید منیزیم، نمونه‌ها در قلمرو A و فاصله رگه­های پگماتوییدی از منبع تغذیه­ کننده سیال آن­ها حدود 1 کیلومتر می­باشد. دایک­ها شیب­ کم تا قائم و ضخامت­ متغیر دارند و امتداد غالب آن­هاNW-SE  است. فابریک‌هایی ماگمایی مانند جهت­یابی کانی‌ها و انکلاو‌ها، بافت نواری در داخل دایک و فابریک‌هایی مانند خطواره‌های حرارتی در سطح خارجی دایک در تعامل با سنگ میزبان در آن­ها شکل گرفته است. با توجه به مشاهدات صحرایی و مطالعات میکروسکوپی دایک‌های منطقه از نظر دگرشکلی در سه نوع مختلف دایک‌های اتساعی (کششی)، دایک‌های فعال و دایک‌های میلونیتی طبقه­بندی می‌شوند. دایک‌های اتساعی در شکستگی‌های موجود در سنگ میزبان (درزه، گسل، برگوارگی شیست) شکل گرفته‌اند و بافت شانه‌ای در این نوع از دایک‌ها شکل گرفته است. حضور این بافت نرخ بازشدگی کم تا متوسط شکستگی‌ها را نشان می‌دهد. دایک­های نوع دوم فعال هستند و فشار ماگما باعث ایجاد بافت نواری در دایک‌ها به موازات دیواره شده است. نوع سوم دایک­های میلونیتی هستند و شواهد دگرشکلی حالت جامد دارند. این دایک­ها بعد از سرد شدن مجددا تحت تاثیر پهنه‌های برشی تغییر شکل یافته‌اند و شواهد ریز ساختاری دمای بالای دگرشکلی آن­ها را نشان می‌دهند.

کلیدواژه‌ها


عنوان مقاله [English]

The Study of Chemistry and Magmatic - Tectonic Fabrics in Pegmatoid Dikes, Southeastern Hamedan

نویسندگان [English]

  • L. Izadi kian 1
  • A. Torkian 2
1 Assist. Prof., 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
چکیده [English]

In the southeastern region of Hamadan, numerous pegmatitic dikes have intruded into the schists. These dikes consist of a mineralogical composition that includes albite, alkali feldspar, tourmaline, quartz, and muscovite. Based on point analyses, the tourmalines are identified as schorl, the feldspars as orthoclase, the plagioclases as albite, and the muscovites as a member of the muscovite-seladonite group. Considering the Fe# ratio against magnesium oxide, the samples are situated in domain A, and the distance of the pegmatitic veins from their fluid source is about 1 kilometer. The dikes have low to vertical dips and variable thicknesses, with a dominant trend of NW-SE. Magmatic fabrics such as mineral orientation and enclaves, banded texture within the dike, and fabrics resembling thermal lineations on the external surface of the dike have formed in interaction with the host rock. Based on field observations and microscopic studies, the dikes in the area are classified into three different types concerning their deformation: extensional dikes (tensional), active dikes, and mylonitic dikes. Extensional dikes have formed in the fractures within the host rock (joints, faults, schistosity) and exhibit a comb texture, which indicates a low to moderate opening rate of the fractures. The second type, the active dikes, have a magmatic pressure that has resulted in a banded texture parallel to the walls. The third type, the mylonitic dikes, show evidence of solid-state deformation. These dikes have been re-deformed after cooling under the influence of shear zones, and their high-temperature deformation microstructural evidence is apparent.

کلیدواژه‌ها [English]

  • Dike
  • Pegmatite
  • Fabric
  • Aspect Ratio
  • Hamedan
Abdullin, R., Melnik, R., Rust, A., Blundy, J., Lgotina, E., and Golovin, V (2024) Ascent of volatile-rich felsic magma in d yk es: a numerical model applied to deep-sourced porphyry intrusions, Geophysics, 236: 1863–1876.
Ahmadi-Bonakdar, S., Tabatabaei Manesh, S. M. and Mirlohi, A (2023) Investigation on tourmaline occurrence in the metamorphic complex in the north of Golpayegan, Sanandaj-Sirjan Zone. Petrological Journal, 13 (4): 87-106.
Alsop, G. I., Strachan, R. A., Holdsworth, R. E., Burns, I. M (2021) Geometry of folded and boudinaged pegmatite veins emplaced within a strike-slip shear zone: a case study from the Caledonian orogen, northern Scotland. J. Struct. Geol. 142: 104233.
Azizi, H., Daneshvar, N., Rafat, Gh., Asahara, Y., K., Takehara, M., Kon, Y., Minami, M., Anma, R (2024) O–Hf isotope ratios of Alvand S-type granite, western Iran, reveal crustal melting in an extensional regime, LITHOS 464–465, 107437.
Badrazadeh, Z (2002) Petrology of Metamorphic Rocks in the Sarabi-Tuisarkhan Area with Special emphasis on the nature of Ultra-High-Grade Metamorphics. Msc Thesis, Earth Sciences Research Institute, 150 pp.
Bahramzade, E., Bagheri, S., Damanu Gol, Sh, Arefnejad, M (2022) Investigating the tectonomagmatic origin of tourmaline in the felsic dikes of the Deh-Salm Metamorphic Complex, East of Lut block. Petrological Journal, 13 (3): 85-104. 
Berberian, M., Alavi, M (1977) Structural Analyses of Hamedan metamorphic tectonites: A paleotectonic discussion, geological survey Iran, 40: 263-279.
Bleeken, G. V. D., Corteel, C., Haute, P. V. D (2007)  Epigenetic to low-grade tourmaline in the Gdoumont metaconglomerates (Belgium): A sensitive probe of its chemical environment of formation”, Lithos, 95 (2): 165–176.
Butler, R. W., Torvela, T (2018) The competition between rates of deformation and solidification in syn-kinematic granitic intrusions: resolving the pegmatite paradox. J. Struct. Geol, 117: 1–13.
Clemente, C. S., Amorós, E. B., Crespo, M. G (2007) Dyke intrusion under shear stress: Effects on magnetic and vesicle fabrics in dykes from rift zones of Tenerife (Canary Islands),  29 (12): 1931-1942.
Currie, K. L., Ferguson, J (1970) The mechanism of intrusion of lamprophyre dykes indicated by ‘‘offsetting’’ of dykes. Tectonophysics, 9: 525-535.
Das, A., Mallik, J (2020) Applicability of AMS technique as a flow fabric indicator in dykes: Insight from Nandurbar-Dhule Deccan dyke swarm. International Journal of earth Sience, 3: 933-944.
Datta, S., Banerjee, S., Samal, A. K., Srivastava, R. K (2023)  Aspect ratio analysis of distinct Paleoproterozoic mafic dyke swarms and related fracture systems in the Eastern Dharwar Craton, India: Implications for emplacement mechanism and depth of origin,  Physics of the Earth and Planetary Interiors, 336: 106998.
Delaney, P., Pollard, D. D (1981) Deformation of host rocks and flow of magma during growth of Minette dykes and breccia-bearing intrusions near Ship Rock, New Mexico. U.S. Geological Survey Professional Paper 1202, 61 p.
Druguet, E., Casta˜no, L. M (2010) Analysis of syntectonic magmatic veins at the mesoscale. J. Geol. Soc. India, 75 (1): 60–73.
Druguet, E., Czeck, D. M., Carreras, J., Casta˜no, L. M (2008) Emplacement and deformation features of syntectonic leucocratic veins from Rainy Lake zone (Western Superior Province, Canada). Precambrian Res, 163 (3–4): 384–400.
Eghlimi, B (2000) Geological map of Hamadan with scale of 1/100,000. Geological Survey and Mineral Exploration of Iran, No, 5759.
Ghasemi, A and Talbot, C. J (2006) A new tectonic scenario for the Sanandaj- Sirjan zone (Iran). Journal of Asian Earth Sciences, 26: 683–93.
Gudmundsson, A (2000) Dynamics of volcanic systems in Iceland: Example of tectonism and volcanism at juxtaposed hot spot and mid-ocean ridge systems. Annual Review Earth and Planetary Sciences, 28: 107-140.
Hassanzadeh, J and Wernicke, B. P (2016) The Neotethyan Sanandaj-Sirjan zone of Iran as an archetype for passive margin-arc transitions. Tectonics, 35: 586–621.
Hawthorne, F. C and Henry, D. J (1999) Classification of the minerals of the tourmaline group”. European journal of mineralogist, 11: 201-215.
Henry, D. J., Novák, M., Hawthorne, F. C., Ertl, A., Dutrow, B. L., Uher, P., and Pezzotta, F (2011) Nomenclature of the tourmaline-supergroup minerals. American Mineralogist, 96 (5-6): 895-913.‏
Imanpournamin, A., Sarkarinejad, Kh (2021) Strutural significance of the Alvand mantled granite- gneiss dome exhumation within the Zagros hinterland fold and thrust belt, Iran, International Journal of Earth Sciences, 111: 195–214.
Izadi Kian, L (2009) Structural and Petrofabric Analysis of Metamorphic Rocks in Alvand Mountain (South and Southwest of Hamadan). Ph. D Thesis, Shahid Beheshti University, 150 pp.
Izadi Kian, L., Alavi, A., Mohajjel, M., and Sepahi, A (2009) Poly phase deformation in the Kamari - Dehno Asadollah Khan Area, Southeast of Hamadan. Iranian Journal of Geological Sciences, Issue, 11: 187-198.
Kerrick, D. M (1987) Fibrolite in contact aureoles of Donegal, Ireland, American Mineralogist, 72 (3-4): 240-254.
Klu¨gel, A., Walter, T. R., Schwarz, S., Geldmacher, J ( 2005) Gravitational spreading causes en-echelon diking along a rift zone of Madeira Archipelago: an experimental approach and implications for magma transport. Bulletin of Volcanology, 68 (1): 37e46.
Kusumoto, S., N. Geshi, and Gudmundsson, A (2013) Aspect ratios and magma overpressures of non-feeder dikes observed in the Miyake-jima volcano (Japan), and fracture toughness of its upper part, Geophys. Res. Lett., 40: 1065–1068, doi:10.1002/grl.50284.
Mahmoudi, S., Corfu, F., Masoudi, F., Mehrabi, B., Mohajjel, M (2011) U–Pb dating and emplacement history of granitoid plutons in the northern Sanandaj–Sirjan Zone, Iran. Journal of Asian Earth Sciences,  41 (3): 238-249.
McGuire, W. J., Pullen, A. D (1989) Location and orientation of eruptive fissures and feeder dykes at Mount Etna; influence of gravitational and regional stress regimes.  Journal of Volcanology and Geothermal Research, 38: 325e344.
Mehdipour-Ghazi, J and Moazzen, M (2015) Geodynamic evolution of the Sanandaj-Sirjan Zone, Zagros Orogen, Iran. Turkish Journal of Earth Sciences, 24: 513–28.
Monfaredi, B., Hauzenberger, C., Neubauer, F., Schulz, B.,  Genser, J., Shakerardakani, F., Halama, R (2020) Deciphering the Jurassic–Cretaceous evolution of the  Hamadan metamorphic complex during Neotethys subduction, western Iran, International Journal of Earth Sciences, 109: 2135-2168.
Muller, J. R., Ito, G., Martel, S. J. (2001) Effects of volcano loading on dyke propagation in an elastic half-space. Journal of Geophysical Research, 106 (B6): 11101-11113.
Pan, X., Shen, Z., Roberts, A. P., Heslop, D., Shi, L (2014) Syntectonic emplacement of Late Cretaceous mafic dyke swarms in coastal southeastern China: insights from magnetic fabrics, rock magnetism and field evidence, Tectonophysics, 637: 328-340.
Papeschi, S., Mazzarini, F., Musumeci, G., Cruden, A. R (2022) Emplacement of a felsic dyke swarm during progressive heterogeneous deformation, Eastern Elba Dyke Complex (Island of Elba, Italy). Journal of Structural Geology, 159: 104600.‏
Passchier, C. W., and Trouw, R. A (2005) Microtectonics. Springer Science & Business Media.‏
Pirajino, F., Smithies, R. H (1992) The FeO / (FeO + MgO) ratio of tourmaline: A useful indicator of spatial variations in granite-related hydrothermal mineral deposits”, Journal of geochemical explorations, 42: 371-381.
Pollard, D. D (1987) Elementary fracture mechanics applied to the structural interpretation of dykes. In: Halls, H. C., Fahrig, W. F. (Eds.), Geological Association of Canada Special Paper 34. Mafic Dyke Swarms, 5-24.
Pollard, D. D., Muller, O. H., Dockstaeder, D. R (1975) The form and growth of fingered sheet intrusions. Geological Society of America Bulletin, 86: 351-363.
Rochette, P (1987) Magnetic susceptibility of the rock matrix related to magnetic fabric studies. Journal of Structural Geology, 9 (8): 1015-1020.
Rochette, P., Aubourg, C., (1991) Is this magnetic fabric normal? A review and case studies in volcanic formations,  307 (1-2): 219-234.
Rockhold, J. R., Nabelek, P. I., Glascock, M. D (1987) Origin of rhythmic layering in the Calamity Peak satellite pluton of the Harney Peak Granite, South Dakota: the role of boron. Geochimica et Cosmochimica Acta, 51: 487–496.
Salami, S (2016) Study of Pegmatites and Aplitic Rocks in the Borujerd, Hamadan, and Qorveh Areas (Northwest of the Sanandaj-Sirjan Zone). Ph. D Thesis, Faculty of Basic Sciences, Bu-Ali Sina University, Hamadan, 295 pp.
Salimi, M. and Alipoor, R (2023). Active tectonics assessment of the southeastern faults of the Hamadan city. Quaternary Journal of Iran, 9 (1-2).
Sepahi, A. A., Salami, S., Lentz, D., McFarlane, C., Maanijou, M (2018) Petrography, geochemistry, and U–Pb geochronology  of pegmatites and aplites associated with the Alvand intrusive  complex in the Hamedan region, Sanandaj–Sirjan zone, Zagros orogen (Iran), International Journal of Earth Sciences, 107: 1059-1096.
Sepahi, A. A., Vahidpour, H., Lentz, D. R., McFarlane, C. R., Maanijou, M., Salami, S., Miri, M., Mansouri, M., Mohammadi, R (2020) Rare sapphire-bearing syenitoid pegmatites and associated granitoids of the Hamedan region, Sanandaj–Sirjan zone, Iran: analysis of petrology, lithogeochemistry and zircon geochronology/trace element geochemistry. Geological Magazine, 157(9): 1499-1525.‏
Sepahi, A. A., Salami, S., Maanijou, M (2020) The study of petrography and mineral chemistry in aplite-pegmatites from Simin valley (south of Hamedan), Iranian Journal of Crystallography and Mineralogy, 28 (1): 37-50.
Shahbazi, H., Siebel, W., Pourmoafee, M., Ghorbani, M., Sepahi, A., Shang, C (2010) Geochemistry and U–Pb zircon geochronology of the Alvand plutonic complex in Sanandaj–Sirjan Zone (Iran): New evidence for Jurassic magmatism. Journal of Asian Earth Sciences, 39(6): 668-83.
Smith, R. P (1987) Dyke emplacement at Spanish Peaks. In: Halls, H.C., Fahrig, W.F. (Eds.), Geological Society of Canada Special Paper 34. Mafic Dyke Swarms, Colorado, pp. 47-54.
Staudigel, H., Gee, J. S., Tauxe, L., Varga, R. J (1992) Shallow intrusive directions in sheeted dykes in the Troodos ophiolite: Anisotropy of magnetic susceptibility and structural data. Geology, 20: 841-844.
Tibaldi, A (2003) Influence of cone morphology on dykes, Stromboli, Italy. Journal of Volcanology and Geothermal Research, 126 (1-2): 79-95.
Tian, Y., and Shan, Y (2011) The diversity of flow structures in felsic dykes. Journal of the Geological Society, 168(4): 1001-1011.‏
Trumbull, R. B and Chaussidon, M (1999) Chemical and boron isotopic composition of magmatic and Hydro thermal tourmaline from the Sinceni granite–  pegmatite system in Swaziland, Chemical Geology, 153: 125–137.
Valizadeh, M. V., and Torkian, A (1999) Petrographic and Petrological Study of Pegmatites in the Hamadan Region. Journal of Sciences, University of Tehran, 2: 121-135.
Varga, R. J., Gee, J. S., Staudigel, H., Tauxe, L (1998) Dike surface lineations as magma flow indicators within the sheeted dike complex of the Troodos ophiolite, Cyprus. Journal of Geophysical Research: Solid Earth, 103(B3): 5241-5256.‏
Webber, K. L., Falster, A. U., Simmons, W. B., Foord, E. E (1997) The role of diffusion controlled oscillatory nucleation in the formation of line rock in pegmatite– aplite dikes. Journal of Petrology, 38: 1777–1791.
Whitney, D. L., and Evans, B. W (2010) Abbreviations for names of rock-forming minerals. American mineralogist, 95(1): 185-187.‏
Yavuz, F., Gultekin, A. H., Karakaya, M. C (2002) CLASTOUR: a comuter program for classification of the minerals of the tourmaline group", Computers Geosciences, 28: 1017-1036.