ژئوشیمی رادیو ایزوتوپ ها Rb–Sr و Sm–Nd، سن سنجی زیرکن U-Pb و تعیین منشأ لیکوگرانیت های خواجه مراد، مشهد، ایران

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه پژوهشی اکتشاف ذخایر معدنی خاور ایران، دانشگاه فردوسی مشهد، مشهد، ایران گروه زمین‌شناسی دانشگاه کلرادو، بولدر، امریکا

2 گروه زمین‌شناسی دانشگاه کلرادو، بولدر، امریکا

چکیده

بیوتیت مسکوویت لیکوگرانیت و پگماتیت­های همراه در متاافیولیت و متافلیش­ها (بقایای پوسته اقیانوسی پالئوتتیس) همزمان با برخورد صفحه ایران با صفحه توران نفوذ نموده­اند. چهار نوع دایک پگماتیتی که بیوتیت مسکوویت لیکوگرانیت­ها را قطعه کرده‌­اند، شناسایی شدند. با استفاده از روشU-Pb  سن زیرکن، بیوتیت مسکوویت لیکوگرانیت 205.9 ± 4.1 Ma  تعیین شد (راتین، تریاس بالایی). بیوتیت مسکوویت لیکوگرانیت و آپلیت گرانیت از نظر شیمیایی، فوق آلومینیم و گرانیت نوع S است. عدد پذیرفتاری مغناطیسی بیوتیت مسکوویت لیکوگرانیت و آپلیت گرانیت میان  SI 5-10 * 5 تا 11 و نسبتFe2O3/FeO  کمتر از 35/0 است، بنابراین مربوط به سری ایلمینیت (نوع کاهیده) هستند. مجموع عناصر کمیاب خاکی بیوتیت مسکوویت لیکوگرانیت میان 130 تا 176 و آپلیت گرانیت میان 50 تا 79 است. Eu ناهنجاری منفی جزئی (Eu/Eu* برابر 52/0تا 76/0) نشان می‌دهد. نسبت ایزوتوپ اولیه (87Sr/86Sr)i و i(143Nd/144Nd) اولیه با توجه به سن 205 میلیون سال محاسبه شد. نسبت ایزوتوپ اولیه (87Sr/86Sr)i در بیوتیت مسکوویت لیکوگرانیت و آپلیت گرانیت به ترتیب 708161/0 و 709853/0 بوده است. نسبت (143Nd/144Nd)i اولیه در بیوتیت مسکوویت لیکوگرانیت  512214/0 و در دایک آپلیت گرانیت 512024/0 بـوده اسـت. میـزان ایزوتوپ اولیه ε Nd در بیوتیت مسکوویت لیکوگرانیت 48/6- و در دایک آپلیت گرانیت 83/6- است. بر اساس داده­های ایزوتوپی ماگمای اولیه از پوسته قاره­ای منشأ گرفته است. به توجه به نسبت‌های Rb/Sr برابر 1 تا 3/1 وCaO/Na2O  کم و بیش 3/0 در بیوتیت مسکویت لیکوگرانیت  ترکیب سنگ منشأ بین متاپلیت و متا پسامیت بوده است.
 

کلیدواژه‌ها


عنوان مقاله [English]

Rb–Sr and Sm–Nd Isotopic Compositions, U-Pb Age and Petrogenesis of Khajeh Mourad Paleo-Tethys Leucogranite, Mashhad, Iran

نویسندگان [English]

  • M. H. Karimpour 1
  • G. L. Farmer 2
  • C. R. Stern 2
1 Research Center for Ore Deposit of Eastern Iran, Ferdowsi University of Mashhad, Mashhad, Iran Dept of Geological Sciences, University of Colorado, CB-399, Boulder, CO, USA
2 Dept of Geological Sciences, University of Colorado, CB-399, Boulder, CO, USA
چکیده [English]

Biotite-muscovite leucogranite and associated pegmatite intruded meta-ophiolite and meta-flysch (the remnants of Paleo-Tethys) during collision of Turan plate with Iran plate.  Four types of pegmatite dykes, crosscutting biotite muscovite leucogranite, are identified. The results of U-Pb zircon age of Khajeh Mourad biotite muscovite leucogranite is 205.9 ± 4.1 Ma (Late Triassic, Rhaetian). Chemically, biotite muscovite leucogranite and aplite granite are peraluminous S-type pluton. Magnetic susceptibility of biotite muscovite leucogranite and aplite granite are between than 0-5 × 10-5 and the ratio of ferric to ferrous ratio (< 0.35),therefore they are classified as belonging to the ilmenite-series (reduced type). The total REE content of biotite muscovite leucogranite is between TREE = 130-176 and aplite is very low Total REE = 50.79. They have small negative Eu anomalies (Eu/Eu*= 0.52 to 0.76). The initial 87Sr/86Sr and (143Nd/144Nd)i was recalculated to an age of 205 Ma.  Initial 87Sr/86Sr ratios for B-M leucogranite and aplite are 0.708161-0.709853. The (143Nd/144Nd)i isotope composition for B-M leucogranite 0.512214, aplite dykes 0.512024. Initial ε Nd isotope values for B-M leucogranite -6.48 and aplite dykes is -6.83. These values could beconsidered as representative of continental crust-derived magmas. The ratios of Rb/Sr = 1-1.3 and CaO/Na2O » 0.3 of biotite-muscovite leucogranite indicate that the source rock had a composition between meta-pelite and meta-psammite.

کلیدواژه‌ها [English]

  • U-Pb
  • Zircon
  • Leucogranite
  • Ilmenite Series
  • Magnetic Susceptibility
  • Pegmatite
References
Abbasi, H., 1998- Petrology of regional and contact metamorphic rocks south of Mashhad, M.Sc. thesis. TehranUniversity.
Alavi, M., 1979- The Virani ophiolite complex and surrounding rocks, Geology rundsch 68: 334-341.
Alavi, M., 1991- Sedimentary and structural characteristics of the Paleo-Tethys remnants in northeastern Iran, Geological Society of America Bulletin 103, 8: 983-992.
Alavi, M., 1992- Thrust tectonics of the Binaloud region; NE Iran, Tectonics 11, 2: 360-370.
Alberti, A. & Moazez, Z., 1974- Plutonic and metamorphic rocks of the Mashhad area (northeastern Iran, Khorasan), Boll. Soc. Geol. Italy 93: 1157-1196.
Alberti, A., Nicoletti, M. & Petrucciani, C., 1973- K-Ar Ages of micas of Mashhad granites, Period Miner. 42: 483-493.
Azevedo,  M. R. & Nolan J., 1998- Hercynian late-post-tectonic granitic rocks from the Fornos de Algodres area Northern Central Portugal,  Lithos 44: 1–20
Barker, F., 1979- Trondhjemite: definition, environment and hypotheses or origin, In Barker, F. (ed) Trondhjemites, dacites, and related rocks, 1-12 New York: Elsevier.
Beard, J. S. & Lofgren, G. E., 1991- Dehydration melting and water-saturated melting  of basaltic andesitic greenstones and amphibolites at 1, 3, and 6.5 kb, Journal of Petrology 32: 365-401.
Beard, J. S., Abitz, R. J. & Lofgren, G. H., 1993- Experimental melting of crustal xenoliths from kilbourne Hole, New Mexico and implication for the contamination and genesis of magmas, Contribution to Mineralogy and petrology 115: 88-103.
Behrmann, J., Drozdzewski, G., Heinrichs, T., Huch, M., Meyer, W. & Oncken, O., 1991- Crustal-scale balanced cross sections through the Variscan fold belt, Germany: the central EGT-segment, Tectonophysics 142: 173–202.
Boynton, W. V., 1984- Cosmochemistry of the rare earth elements; meteorite studies, In: Rare earth element geochemistry. Henderson, P. (Editors), Elsevier Sci. Publ. Co., Amsterdam: 63-114.

Castro, A., Guillermog, L., Corretge, G., El-Baid, M., El-Hmid, H., Fernanadez, C. & Patin˜o-Douce, A. E., 2000- Experimental Constraints on Hercynian Anatexis in the Iberian Massif, Spain, Journal of Petrology 41: 1471-1488.

Chappell, B. W. & White, A. J. R., 1974- Two contrasting granite types, Pacif Geol. 8: 173174.
Conrad, W. K., Nicholls, I. A. & Wall, V. J., 1988- Water-saturated and undersaturated melting of meta-aluminous and per-aluminous crustal compositions at 10 kb: evidence for the origin of silicic magmas in the Taupo volcanic zone, New Zealand, and other occurrences, Journal of Petrology 29: 765-803.
Davoudzadeh, M. & Schmidt, K., 1984- Plate tectonics, orogeny, and mineralization in the Iranian fold belts, report of a German-Iranian research program 1977-19. Neues Jahrbuch fuer Geologie und Palaeontologie. Abhandlungen. 168, 2-3: 182-207.
DeBon, F., Le Fort, P., Sheppard, S. M. F. & Sonet,  J., 1986- The four plutonic belts of the Transhimalaya-Himalaya: a chemical, mineralogical, isotopic, and chronological synthesis along a Tibet- Nepal section, Journal of Petrology 27: 219250.
Didier, J. & Lameyre, J., 1969- Les granites du Massif Central Franiais. Etude compare´ e des leicogranites et granodiorites, Contributions to Mineralogy and Petrology 24: 219238.
Eftekharnezhad,  J. & Behroozi, A., 1989- Geodynamic and significance of recent discoveries of ophiolite and Late Paleozoic rocks in Ne Iran (including Kopet Dogh), Geological Survey of Iran, internal report, 21 p.
Fakhr, M. S., 1977- Contribution a l etode de la flore Rheto- liasique De la formation de Shemshak de lElbourz (Iran),  C.T.H.S. Mem.Sect. Sci, Bibliotheque Nationale Paris, no. 5, 178p.
Gardien, V., Thompson, A. B., Grujic, D. & Ulmer, P., 1995- Experimental melting biotite + quartz Muscovite assemblages and implications for crustal melting. Journal of Geophysical Research 100, B8: 15581-15591.
Gebauer, D., Schertl, H. P., Brix, M. & Schreyer, W., 1997- 35 Ma old ultrahigh-pressure metamorphism and evidence for very rapid exhumation in the Dora Maira Massif. West. Alps, Lithos 41: 5–24.
Gehrels, G. E. & Valencia, V., 2006- A. Pullen in Geochronology: Emerging Opportunities, ed. T. Loszewski and W. Huff, Paleo. Soc. Pap., 12, 2006: 67-76.
Ghazi, M., Hassanipak, A. A., Tucker, P. J. & Mobasher, K., 2001- Geochemistry and 40Ar-39Ar ages of the Mashhad Ophiolite, NE Iran, abstracts as: Eos. Trans. AGU, 82(47), Fall Meet.
Harris, N. B. W. & Inger, S., 1992- Trace element modeling of pelite- derived granites, Contributions to Mineralogy and Petrology 110: 46– 56.
Harris, N. B. W. & Massey, J., 1994- Decompression and anatexis of Himalayan metapelites, Tectonics 13: 1537– 1546.
Holtz,  F. & Johannes, W., 1991- Genesis of peraluminous granitesI. Experimental investigation of melt compositions at 3 and 5 kbar and various H2O activities, Journal of Petrology 32: 935-58.
Holtz, F. &  Barbey, P., 1991- Genesis of peraluminous granites II. Mineralogy and chemistry of the Tourem Complex (North Portugal). Sequential melting vs. restite unmixing, Journal of Petrology 32: 959978.
Inger, S. & Harris, N.,1993- Geochemical constraints on leucogranite magmatism in the Langtang Valley, Nepal Himalaya, Journal of Petrology 34: 345368.
Iranmanesh,  J. & Sethna, S. F., 1998- Petrography and geochemistry of the Mesozoic granite at Mashhad, Khorasan Province, northeastern part of Iran, Journal of the Geological Society of India 52: 1, 87-94.
Ishihara, S., 1977- The magnetite-series and ilmenite-series granitic Rocks, Mining Geology 27: 293¯305
Jarchovski, T., Momenzadeh,  M., Tadayon, A. & Ziegler, V., 1973- Mineral reconnaissance in Mashhad Quadrangle, Geol. Surv. Of Iran. P. 192.
Karimpour, M. H., 2009- Rb-Sr and Sm-Nd Isotopic Composition, U-Pb-Th (zircon) Geochronology and Petrogenesis of Mashhad Paleo-Tethys granitoids, Ferdowsi University of Mashhad, Iran (grant P/742-87/7/14).  
Khatonie Molayossefi, M., 2000- The study of stratigraphy and plants fossils of Shemshak formation in Shandiz area, M.S thesis. 222p
Kunin N. et al.,  1987- Map of depth to Moho,  Moscow, Institute of Physics of the Earth.   
Le Breton, N. &  Thompson, A. B.,1988- Fluid-absent (dehydration) melting of biotite in metapelites in the early stages of crustal anatexis, Contributions to Mineralogy and Petrology 99: 226-237.
Le Fort, P., Michard, A., Sonet, J. & Zimmerman, J. L., 1983- Petrography, geochemistry and geochronology of some samples from the Karakorum axial batholith (Northern Pakistan), In: Shams, F.A. (Ed.), Granites of the Himalayas, Karakorum and Hindukush. Inst. of Geology, PunjabUniv., Lahore: 377-387.
Majidi, B., 1981- The ultrabasic lava flows of Mashhad, North East Iran, Geological Magazine 118, 1: 49-58.
Majidi, B., 1983- The geochemistry of ultrabasic and basic lava flows occurrences in northeastern Iran, In Geodynamic project in Iran, Geological Survey of Iran Report No. 51: 463-477.
Miller, J. M., 1985- Are strongly peraluminous magmas derived from pelitic sedimentary sources, Journal of Geology 93: 673-689.
Mirnejad, H., 1991- geochemistry and petrography of Mashhad granites and pegmatites, M.Sc. thesis, TehranUniversity.
Moazez Lesco, Z. & Plimer, I. R., 1979- Intrusive and polymetamorphic rocks of the Darakht-Bid area, near Mashhad, Iran, Geologische Rundschau. 68, 1: 318-333. 
Pamic, J., Lanphere, M. & Belak, M., 1996- Hercynian I-type and S-type granitoids from the Slavonian mountains (southern PannonianBasin, northern Croatia), N. Jb. Mineral.  Abh. 171: 155-186
Patin˜o-Douce, A. E. & Beard, J. S., 1995- Dehydration-melting of biotite gneiss and quartz amphibolites from 3 to 15 kbar, Journal of Petrology 36: 707-738.
Patin˜o-Douce, A. E. & Harris, N., 1998- Experimental constraints on Himalayan anatexis, Journal of Petrology 39: 689– 710.
Patin˜o-Douce, A. E. & Johnston, D. A., 1991- Phase equilibria and melt productivity in the pelitic system: implication for the origin of peraluminous granitoids and aluminous granulites, Contribution to Mineralogy and Petrology 107: 202-18.
Pearce, J. A., Harris, N. B. W. & Tindle, A. G., 1984- Trace element discrimination diagrams for the tectonic interpretation of granitic rocks, Journal of Petrology25 (4): 956-983.
Peterson, J. W. & Newton, R. C., 1989- Reversed experiments on biotite-quartz-feldspar melting in the system KMASH: implications for crustal anatexis, Journal of Geology 97: 465-486.
Petford, N. & Atherton, M., 1996- Na-rich partial melts from newly underplated basaltic crust: the Cordillera Blanca Batholith, Per. Journal of Petrology 37: 1491-1521.
Phillips, G. N., Wall, V. J. & Clemens, J. D., 1981- Petrology of the Strathbogie batholith: a cordierite-bearing granite, Canadian Mineralogist 19: 4763.
Robinson, P., Higgins, N. C. & Jenner, G., 1986- Determination of rare-earth elements, Yttrium and Scandium in rocks by using an ion exchange-X-Ray Fluorescence technique. Chemical Geology 55: 121-137
Rottura, A., Del Moro, A., Pinarelli, L., Petrini, R., Caggianelli, A., Bargossi, G. M. & Piccarreta, G., 1991- Relationships between intermediate and acidic rocks in orogenic granitoid suites: petrological, geochemical and isotopic (Sr, Nd, Pb) data from Capo Vaticano (southern Calabria, Italy), Chem. Geol. 92: 153-176
Searle, M. P., Parrish, R. R., Hodges, K.V., Hurford, A., Ayres, M.W. & Whitehouse, M. J., 1997- Shisha Pangma leucogranite, south Tibetan Himalaya. field relations, geochemistry, age, origin, and emplacement, J. Geol. 105: 295-317
Shearer, C. K., Papike, J. J., Redden, J. A., Simon, S. B., Walker, R. J. & Laul, J. C., 1987- Origin of pegmatitic granite segregations, Willow Creek, Black Hills, South Dakota, Canadian Mineralogist 25: 159171.
Springer, W. & Seck, H. A., 1997- Partial fusion of basic granulites at 5 to 15 kbar: implication for the origin of TTG magmas, Contribution to Mineralogy and Petrology 127: 30-45.
Stampfli, G. M. & Pillevuit, A., 1993- An alternative Permo-Triassic reconstruction of the kinematics of the Tethyan realm, In: J. Dercourt, L.-E. Ricou and B. Vrielinck (Eds.), Atlas Tethys Palaeoenvironmental Maps. Explanatory Notes. Gauthier-Villars Paris: 55-62.
Stampfli, G. M., 1996- The Intra-Alpine terrain: a Paleo-Tethyan remnant in the Alpine Variscides, Eclogae geol. Helv. 89 (1): 13-42.
Stampfli, G. M., 2000- Tethyan oceans, In: E. Bozkurt, J.A. Winchester and J.D.A. Piper (Eds.), Tectonics and magmatism in Turkey and surrounding area. Geological Society of London, Special Publication 173: 163-185.
Stampfli, G. M., 2002- Opening and closure of Paleo-Tethys in Iran, Personal communication.
Stampfli, G. M., Marcoux, J. & Baud, A., 1991- Tethyan margins in space and time, In: J.E.T. Channell, E.L. Winterer and L.F. Jansa (Eds.), Paleogeography and paleoceanography of Tethys. Palaeogeography, Palaeoclimatology, Palaeoecology 87: 373-410.
Stocklin, J., 1974- Possible ancient continental margins  in Iran, The Geology of Continental margins, Edited by C.A. Burk & C.L. Drake: 873-887.
Sylvester, P. J., 1998- Post-collisional strongly peraluminous granites, Lithos 45, Issue 1-4: 29-44.
Thompson, A. B., 1982- Dehydration melting of pelitic rocks and the generation of H2O-undersaturated granitic liquids, American Journal of Science 282: 1567-1595.
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 37: 45-71.
Valizadeh, M. & Karimpour, M. H., 1995- Origin and tectonic setting of Mashhad granitoids, Journal of Sciences, University of Tehran 21, No. 1: 71-82.
Venturelli, G., Thorpe, R. S. Dal Piaz, G. V., Del Moro, A. & Potts, P. J., 1984- Petrogenesis of calc-alkaline, shoshonitic and associated ultrapotassic Oligocene volcanic rocks from the Northwestern Alps, Italy, Contribution to Mineralogy and Petrology 86: 209-220.
Vielzeuf, D. & Holloway, J. R., 1988- Experimental determination of the liquid-absent melting relations in the pelitic system. Consequences for crustal differentiation, Contribution to Mineralogy and petrology 98: 257-76.
Villaseca, C., Barbero, L. &  Herreros, V., 1998- A re-examination of the typology of peraluminous granite types in intra continental orogenic belts, Transaction of the Royal Society of Edinburgh; Earth Sciences 89: 113-119.
Whalen, J. B., Currie, K. L. & Chappell, B. W., 1987- A-type granites. geochemical characteristics, discrimination and petrogenesis, Contributions to Mineralogy and Petrology 95: 407-419.