جایگاه تکتونوماگمایی دیابازها و جریان‌های بازالتی افیولیت شمال مکران، جنوب شرقی ایران
محورهای موضوعی :عزیزالله تاجور 1 , محمدمهدی خطیب 2 * , محمدحسین زرین¬کوب 3
1 - دانشگاه بیرجند
2 - دانشگاه بیرجند
3 - دانشگاه بیرجند
کلید واژه: افیولیت شمال مکران, تولئیت, جریان‌های بازالتی, دیاباز, کالک¬آلکالن.,
چکیده مقاله :
افیولیت شمال مکران در جنوب شرقی ایران، به‌عنوان بخشی از افیولیت های تتیس، در حدفاصل بلوک های قاره ای لوت و باجکان-دورکان قرار دارد. از جمله سنگ‌های تشکیل‌دهنده این توالی افیولیتی، دیابازها و جریان‌های بازالتی هستند که بیشترین برونزد را در شرق منطقه دارند. شواهد ساختاری، سنگ نگاری و زمین شیمیایی بیانگر شکل گیری این سنگ‌ها در جایگاه های زمین ساختی متفاوت است. بر اساس ویژگی های زمین شیمیایی، دیابازها و بازالت‌ها در دو گروه جای می گیرند: در یک گروه، دیابازها و جریان‌های بازالتی با ترکیب تولئیتی قرار دارند که ویژگی‌های شبیه به پشته های میان‌اقیانوسی (MORB) را به نمایش می گذارند. گروه دوم شامل جریان‌های بازالتی تا داسیتی با ترکیب کالک آلکالن است که ویژگی‌های کمان های آتشفشانی را به نمایش گذاشته و نشانه-های محیط‌های فرورانش در آنها دیده می شود. دو رخداد ماگمایی منجر به تشکیل این دو گروه از سنگ‌ها شده است: 1) ماگماتیسم نوع MORB حاصل از کشش و بازشدگی بین دو بلوک قاره ای که منجر به شکل گیری دیابازها و بازالت‌های تولئیتی در کرتاسه پیشین شده است. غنی شدگی این سنگ‌ها نسبت به عناصر نادر خاکی سبک(LREE) و مقادیر پایینLa/Yb و به نسبت بالای U/Th نمایانگر تاثیر ترکیبات قاره ای در مذاب به وجود آورنده آنها است. 2) ماگماتیسم مرتبط با فرورانش که گدازه های بازالتی، آندزیتی و داسیتی دارای ویژگی‌های کالک آلکالن را در کرتاسه پسین برجای گذاشته است. غنی شدگی LREE و LILE، ناهنجاری منفی Nb و Ta، نسبت بالای Pb/Ce و مقدار تمرکز اندک TiO2 در این سنگ‌ها، نمایانگر تاثیر ورقه فرورانشی در ترکیب آنها است.
The north Makran ophiolite in southeast of Iran, as a part of Tethyan ophiolites, is located between Lut and Bajkan-Durkan continental blocks. Among the rocks of this ophiolite sequence, diabase and basalt flows are present more abundant in the outcrops in the eastern part of the studied north Makran ophiolite. Structural, petrographic and geochemical evidences suggest distinct geodynamic setting for the formation of these rocks. Based on geochemical characteristics, diabase and basalts fall into two groups: In the first group, tholeiitic diabase and basalt flows represent MORB-like affinity, and the second group include calc-alkaline basaltic to dacitic lavas with arc environment and supra-subduction affinities. These two lava types represent two major magmatic events: 1) MORB-type magmatism resulted from Early Cretaceous rifting/opening between two continental blocks and resulted in the formation of tholeiitic diabase and basalt. LREE enrichment, low La/Yb and relatively high U/Th ratios suggest continental influence in their melt source, and 2) subduction-related magmatism, that formed calc-alkaline basaltic, andesitic and dacitic lavas in Late Cretaceous. LILE, LREE enrichment, Nb and Ta negative anomaly, low TiO2 concentrations and relatively high Ce/Pb ratio document subduction influence in their composition.
Aghanabati, A., Mahdavi, M. A. and Arshadi, S., 1987. Geological map of Espakeh, scale 1:100000. Geological Survey of Iran.
- Akizawa, N., Arai, S. and Tamura, A., 2012. Behavior of MORB magmas at uppermost mantle beneath a fast-spreading axis: an example from Wadi Fizh of the northern Oman ophiolite. Contributions to Mineralogy and Petrology, 164, 601-625.
- Almalki, K.A., Betts, P.G. and Ailleres, L., 2016. Incipient seafloor spreading segments: Insights from the Red Sea. Geophysical Research letters, 43, 2709–2715.
- Arshadi. S., Mahdavi, M.A. and Eftekhar-Nezhad, J., 1987. Geological map of Fannuj, scale 1:100000. Geological Survey of Iran.
- Babaie, H.A., Ghazi, A.M., Babaei, A., La Tour, T.E. and Hassanipak, A.A., 2001. Geochemistry of arc volcanic rocks of the Zagros Crush Zone, Neyriz, Iran. Journal of Asian Earth Sciences, 19, 61-76.
- Bagci, U., Parlak, O. and Hock, V., 2008. Geochemistry and tectonic environment of divers’ magma generations forming the crustal units of the Kizildag ophiolite, southern Turkey. Turkish Journal of Earth Sciences, 17, 43-47.
- Berberian, M. and King, G.C.P., 1981. Towards a paleo-geography and tectonic evolution of Iran – Reply: Canadian Journal of Earth Sciences, 18, 1764-1766.
- Cawood, P.A., Kröner, A., Collins, W.J., Kusky, T.M., Mooney, W.D. and Windley, B.F., 2009. Accretionary orogens through Earth history. In: Cawood PA, Kröner A (eds) Earth accretionary systems in space and time. Journal of the Geological Society London, 318, 1–36.
- DeMets, C., Gordon, R.G. and Argus, D.F., 2010. Geologically current plate motions. Geophysical Journal International, 181, 1, 1-80.
- Dewey, J.F. and Bird, J.M., 1971. Origin and emplacement of ophiolite Suite-Appalachian ophiolites in Newfoundland. Journal of Geophysical Research, 76, 3179.
- Dilek, Y. and Furnes, H., 2014. Ophiolites and their origins. Elements, 10, 93–100.
- Dolati, A., 2010. Stratigraphy, structural geology and low-temperature thermochronolgy across the Makran accretionary wedge in Iran: [Ph.D. thesis]. Swiss Institute of Technology, 370.
- Donnelly, K.E., Goldstein, S.L., Langmuir, C.H. and Spiegelman, M., 2004. Origin of enriched ocean ridge basalts and implications for mantle dynamics. Earth and Planetary Science Letters, 226, 347-366.
- Eftekhar-Nezhad, J., Arshadi, S., Mahdavi, M.A., Morgan, K.H., McCall, G.J.H. and Huber, H., 1979. Fannuj Quadrangle Map 1:250'000. Ministry of Mines and Metal, Geological Survey of Iran.
- Farhoudi, G. and Karig, D.E., 1977. Makran of Iran and Pakistan as an active arc system. Geology, 5, 664-668.
- Grove, T.L. and Kinzler, R.J., 1986. Petrogenesis of andesites. Annual Review of Earth and Planetary Sciences, 14, 417-454.
- Haghipour, N., Burg, J.P., Kober, F., Zeilinger, G., Ivy-Ochs, S., Kubik, P.W. and Faridi, M., 2012. Rate of crustal shortening and non-Coulomb behavior of an active accretionary wedge: The folded fluvial terraces in Makran (SE, Iran). Earth and Planetary Science Letters, 355, 187-198.
- Hastie, A.R., Keer, A.C., Pearce, J.A. and Mitchell, S.F., 2007. Classification of altered volcanic island arc rocks using immobile trace elements: development of the Th-Co discrimination. Journal of Petrology, 48, 2341-2357.
- Hunziker, D., Burg, J.P., Moulas, E., Reusser, E. and Omrani, J., 2017. Formation and preservation of fresh lawsonite: Geothermobarometry of the North Makran Blueschists, southeast Iran. Metamorphic Geology, 7, 1–25.
- Le Bas, M.J., Lemaitre, R.W., Streckeisen, A. and Zanettin, B., 1986. A chemical classification of volcanic-rocks based on the total alkali silica diagram. Journal of Petrology, 27,3, 745-750.
- McCall, G.J.H. and Kidd, R.G.W., 1982. The Makran, southeastern Iran; the anatomy of a convergent plate margin active from Cretaceous to present. In: Jeremy, K. L. (ed.) Trench-Fore-arc geology; sedimentation and tectonics on modern and ancient active plate margins. Conference, London, United Kingdom, Geological Society of London, 387 -397.
- McCall, G.J.H., Eftekhar-Nezhad, J., Samimi-Namin, M. and Arshadi, S., 1985. Explanatory text of the Fannuj quadrangle map 1:250,000. In: McCall, G.J.H. (Ed.). Ministry of Mines and Metals, Geological Survey of Iran.
- McCall, G.J.H., 1997. The geotectonic history of the Makran and adjacent areas of southern Iran. Journal of Asian Earth Sciences, 15, 517-531.
- MacLeod, C.J., Lissenberg, C.J. and Bibby, L.E., 2013. "Moist MORB" axial magmatism in the Oman ophiolite: The evidence against a mid-ocean ridge origin. Geology, 41, 459-462.
- Moghadam, H.S. and Stern, R.J., 2011. Late Cretaceous fore-arc ophiolites of Iran. Island Arc, 20, 1-4.
- Morgan, K.H., McCall, G.J.H. and Huber, H., 1987(a). Geological map of Ramak, scale 1:100000. Geological Survey of Iran.
- Morgan, K.H., McCall, G.J.H. and Huber, H., 1987(b). Geological map of Remeshk, scale 1:100000. Geological Survey of Iran.
- Moslempour, M.E., Khalatbari Jafari, M., Morishita, T. and Biabangard, H., 2017. Petrogenesis of mantle peridotites from the South of Jazmourian, Makran accretionary prism, Iran. Iranian Journal of Earth Sciences, 9, 1-16.
-Nicolas., A., 1989. Structures of Ophiolites and Dynamics of Oceanic Lithosphere. Dodrecht, Netherlands, Kluwer Academic Publishers, 750.
- Noll, P.D., Newsom, H.E., Leeman, W.P. and Ryan, J.G., 1996. The role of hydrothermal fluids in the production of subduction zone magmas: Evidence from siderophile and chalcophile trace elements and boron. Geochimica ET Cosmochimica Acta, 60, 587-611.
- Osozawa, S., Shinjo, R., Lo, C.H., Jahn, B.M., Hoang, N., Sasaki, M., Ishikawa, K., Kano, H., Hoshi, H., Xenophontos, C. and Wakabayashi, J., 2012. Geochemistry and geochronology of the Troodos ophiolite: An SSZ ophiolite generated by subduction initiation and an extended episode of ridge subduction? Lithosphere, 4, 497-510.
- 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.
- Saccani, E., Nicolae, L. and Tassinari, R., 2001. Tectono-magmatic setting of the Jurassic ophiolites from the south Apuseni Mountains (Romania): Petrological and geochemical evidence. Ofioliti, 26,1, 9-22.
- Sengör, A.M.C., 1990. A new model for the late Paleozoic Mesozoic tectonic evolution of Iran and implications for Oman. Geology and Tectonics of the Oman Region, 49, 797-831.
- Shervais, J.W., 1982. Ti–V plots and the petrogenesis of modern and ophiolitic lavas. Earth and Planetary Science Letters, 59, 101–118.
- Slovenec, D., Lugovic, B., Meyer, H.P. and Garapic, G.S., 2011. A tectono-magmatic correlation of basaltic rocks from ophiolite mélanges at the north-eastern tip of the Sava–Vardar suture zone (northern Croatia) constrained by geochemistry and petrology. Ofioliti, 36, 77-100.
- Stöcklin, J., 1968. Structural history and tectonics of Iran: A review. The 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. Geological Society, London, Special Publications, 42,1, 313-345.
- Withney, D.L. and Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185-187.