Document Type : Original Research Paper


1 Departmant of Geology, Islamic Azad University, Shabestar Branch,Shabestar,Iran.

2 Departmant of Geology, Tabriz University, Tabriz, Iran.

3 Institute of Earth Sciences, Academia Sinica, Taiwan

4 Departmant of Geology, Istanbul University, Istanbul,Turkey


In southeast Tabriz, as a part of Western Albourz-Azarbaijan magmatic belt the vocanic and pyroclastic rocks of Sahand cover vast areas. The volcanic rocks include andesite, dacite, rhyodacite and rhyolite and pyroclastic rocks largely occur as vast ignimbritic outcrops. Based on high LILE/HFSE and LREE/HREE ratios and their similar composition to subduction volcanic rock suites; it seems that they have formed in a subduction zone. The subduction process had low effect on the concentration of Zr, Ta, Hf, Sm, Tb, Nd, Eu and Y, while it had strong influence on concentration of Th , U and La. Concentration of elements such as Ba , K , Rb , Cs , Sr , Pb shows that these rocks belong to calc-alkaline series. The studied rocks show considerable similarity with calc-alkaline rocks from Turkey and from this point of view; these rocks belong to post-collisional arcs. In this tectonic setting, magma ascent is controlled by strik-slip faulting and associated pull-apart extensional tectonics. This post-collisional magmatism may have occurred due to Arabian-Iranian plates collision.


بهروزی، امینی فضل و امینی آذر، 1376- نقشه زمین‌شناسی 1:100000 بستان آباد، سازمان زمین‌شناسی و اکتشافات معدنی کشور.
Aldanmaz, E., Pearce, J. A., Thirlwall, M. F & Mitchell, J. G., 2000- Petrogenetic evolution of late Cenozoic, post-collision volcanism in western Anatolia, Turkey. Journal of Volcanology and Geothermal Research, 102:67-95.
Allen, M., Jackson, J. & Walker, R., 2004- Late Cenozoic reorganization of the Arabia-Eurasia collision and the comparison of short-term and Long-term deformation rates, Tectonics, 23, TC2008, doi: 1029/2003TC001530.
Dostal, J., Church, B. N., Reynolds, P. H. & Hopkinson, L., 2001- Eocene volcanism in the Buck Creek basin, central British Columbia (Canada): transition form arc to extensional volcanism. Journal of Volcanology and Geothermal Research. 107: 149-170.
Fan, W. M., Gue, F., Wang, Y. J. & Lin, G., 2003- Late Mesozoic calc-alkaline volcanism of post-orogenic extention in the northern Da Hinggan Mountains, northeastern China. Journal of Volcanology and Geothermal Research. 121: 115-135.
Gioncada, A., Mazzuoli, R., Bisson, M. & Pareschi, M. T., 2003- Petrology of volcanic products younger than 42 ka on the Lipari- Volcano complex (Aeolian Island, Italy): an example of volcanism controlled by tectonics. Journal of Volcanology and Geothermal Research. 122: 191-220.
Gorton, M. P. & Schandl, E. S., 2000- Form continents to island arcs: a geochemical indx of tectonic setting for arc-related and within-plate felsic to intermediate volcanic rocks. The Canadian Mineralogist, 38: 1065-1073.
Harker, A., 1909- The natural history of igneous rocks. Methuen, London.
Hole, M. J., Saunders, A. D., Marriner, G. F. &Tarney, J., 1984- Subduction of pelagic sediments: Implication for the origin of Ceanomalous basalts from Alexander Islands. Journal of Geological Society of London, 141: 453-472.
Irvine, T. N. & Baragar, W. R. A., 1971- A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Science, 8:523-548.
Juteau, T. & Maury, R., 1997- Geologie de la Croute Oceanique: Petrologie et Dynamique Endogenes, 569p.
Karapetian, S. G., Jrbashian, R. T., Mnatsakanian, A. K. H., 2001- Late collision rhyolitic volcanism in the north-eastern part of the Armenia highland. Journal of Volcanology and geothermal Research 12, 189-220.
Keskin, M., Pearce, J. A., Mitchell, J. G., 1998- Volcano-stratigraphy and geochemistry of collision-erlated volcanism on the Eezurum-Kars Plateau, northeastern Turkey. Journal of Volcanology and Geothermal Research 85,355-404.
Krauskopf, K. B. & Bird, D. K., 1976- Introduction to geochemistry. Mcgraw-hill, Inc. 647p.
Le Bas, M. J., Le Maitre, R. W., Streckeisen, A. & Zannetin, B., 1986- Achemical classification of volcanic rocks based on the total alkali-silica diagram, Journal of Petrology, 27:745-750.
Le Maitre, R. W., Bateman, P., Dudek, A., Kellre, J., Lameyre Le Bas, M. J., Sabine, P. A., Schmid, R., Sorenson, H., Streckeisen, A., Woolley, A., & Zanettin, B., 1989- A classification of igneous rocks and glossary of terms. Blackwell Science, Axford. 193p.
Macdonald, R., Hawkesworth, C. J. & Heath, E., 2001- The lesser Antilles volcanic chain: A study in arc magmatism . Earth-Science Reviews. 49: 1-76.
Machado, A., Lima, E. F., Chemale Jr., F., Morata, D., Oteiza, O., Almeida, D. P. M., Figueiredo, A. M. G., Alexandre, F. M. & Urrutia, J. L., 2005- Geochemistry constrains of Mesozoic-Cenozoic calc-alkaline magmatism in South Shetland arc, Antarctica. Journal of South American Earth Sciences. 18: 407-425.
Mccurt, W. J., Atherton, M. P., Sanderson, L. M. & Warden, V., 1985- The volcanic cover chemical composition and the origion of the magma of the calipuy. (In magmatism at a plate edge) . 273-284.
Mohamed, F. H., Moghazi, A. M. & Hassanen, M. A., 2000- Geochemistry, petrogenesis and tectonic setting of late Neoproterozoic Dokhan-type volcanic rocks in the Fatira area, eastern Egypt. International Journal of Earth Science, 88:764-777.
Moinvaziri, H. & Aminsobhani, I., 1978- Volcanological and volcanosedimentological study of SahandMountain. University of Tarbeyat Moallim, Tehran.
Muller, D. & Groves, D. I., 1997- Direct and indirect associations between potassic igneous rocks, Shshonites and gold- copper deposits. Ore Geol. Rev. 8:383-406.
Pearce, J. A., 1982- Trace element characteristic of lava from destructive plate boundaries. In: R.S. Thorope (Editore), Andesites. John Wiley and Sons, Chichester, pp. 525.548.
Pearce, J. A., 1983- Role of the sub0continental lithosphere in magma genesis at active continental margins. In: Hawkesworth C.J. & Norry M.J., (eds.), Continental basalts and mantle xenoliths. Shiva, nantwich, 230-249.
Pearce, J. A. & Peate, D. W., 1995- Tectonic implications of the composition off volcanic arc magmas. Annual review Earth and Planetary Science Letters 23: 251-285.
Rendeng,  S ., Jingsui, Y., Cailai, W., Iizuka, T. & Hirata, T., 2006 - Island Arc Volcanic Rocks in the North Qaidam UHP Belt, Northern Tibet Plateau: Evidence for Ocean-Continent Subduction Followed by Continent-Continent Subduction. The Journal of Asian Earth Sciences, 28: 151-159.
Rollinson, H., 1993- Using geochemical data: evaluation. Presentation, interpretation. Singapore. Ongman, 352p.
Saunders, A. D., Tarnery, J. & Weaver, D., 1980- Transverse geochemical variations across the Antractic Peninsula: Implications for the genesis of calcalkaline magmas. Earth and Planetary Science Letters, 46: 334-360.
Shelley, D., 1993- Igneous and metamorphic rocks under the microscop. Chapman and Hall, 630p.
Singer, S. B., Pearce, H. T., Kolisnik, M. A. & Myers, D. J., 1993- Plagioclase Zoning in mid-Pleistocene lavas from the Seguam volvanic center, central Aleutian arc, Alaska. American Mineralogist, 78: 143-157.
Stoklin, J., 1968- Structural history and tectonics of Iran: a review. Amer. Assoc. Petroleum Geology.Bull.52: 1229-1258.
Stevenson, R., Henry, P. & Gariepy, C., 1999- Assimilation-fractional crystallization origin of Arcean Saukitoid Suties: Western Superrior Province, Canada. Precambrian Reasearch., 96:83-99.
Sun, S. S. & McDonough, W. F., 1989- Chemical and isotopic ystematics of oceanic basalts: Implcations for mantle compos