Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Geochemistry and Tectonic Setting of Western Avaj Gabbros, Northwest of Iran

Document Type : Original Research Paper

Authors
Ali Kananian 1
Omolbanin Mashhadi-Hashemi 1
Abbas Asiabanha 2
Daryoush Esmaeili 3
1 Department of Geology, Faculty of Science, University of Tehran, Tehran, Iran
2 Department of Geology, Faculty of Science, Imam Khomeini international University, Qazvin, Iran
3 Department of Geology, Faculty of Science, University of Tehran, Iran
Abstract
The western Avaj intrusive bodies, composed mainly of gabbroic rocks, have intruded into low grade regional metamorphic rocks of Razan Subzone and formed small and elongated plutons. The gabbroic rocks in the marginal part of intrusions deformed during emplacement and show mylonitic texture. The foliation in the marginal mylonitic gabbro is parallel to the foliation of host metamorphic rocks with NW-SE direction. A narrow low grade metamorphic aureole was formed around these intrusions. Petrologic relationships and the origin of the different intrusive outcrops are demonstrated by petrography and geochemical studies. Geochemical signatures on spider diagram indicate that the role of fractional crystallization on the magma evolution was more important than the contamination or partial melting. Trace element pattern on the spider diagrams suggests an extensional regime for tectonic setting of the gabbroic rocks. Seemingly, these rocks were possibly generated by partial melting of an enriched lithospheric mantle source (EM) in depth of about 50 to 60 kilometers.
Keywords
gabbro
mylonite
extensional tectonic
geochemistry
Avaj

Subjects

Amidi, S.M., 1975-Contribution a l'etude stratigraphique petrologique, et petrochimique de roches magmatiques de la region de Natanz-Nain –Surk (Iran central). These.Doct.Etat, Grenoble.
Ballever, M., Le Goff, E. and Hebert, R., 2001-The tectonothermal evolution of the Caledonian belt of northern Brittany, France: a Neoproterozoic volcanic arc. Tectonophysics, 331, 19-43.
Bolourchi, M.H., 1979-KabudarAhang Geological Map 1:250000, Geological survey of Iran .
Chappel, B.W. and white, A.J.R., 1974 - Two contrasting granite types. Pac. Geol. 8,173.174.
Cox, K.G., Bell, J.D. and Pankhurst, R.J., 1979-  The Interpretation of Igneous Rocks. Allen and Unwin, London. 450p.
Emami, M.H. 1981- Geologie de la region de Qom-Aran (Iran): Contribution a l'etude dynamique et geochimique du Volcanisme tertiaire de l'Iran central. These d'Etat. Univer. Grenoble. France.
Esawi, E.K., 2004 - Evidence from the Farmington pluton for Early Devonian subduction-related magmatism in the Carolina zone of central North Carolina. Journal of Geodynamics 37, 531–548
Fites Gerald, J.D. and Stunitz, H., 1993- Deformation of granitoids at low metamorphic grade I: Reactions and grain size reduction. Tectonophysics, 221: 269-297 p.
Hirose, K. and Kushiro, I., 1993 - Partial melting of dry peridotites at high pressure: determination of compositions of melts segregated from peridotite using aggregates of diamond Earth planet Sci lett. 114, 477-489.
Jung, S. and Hoernes, S.. 2000 - The major and trace element and isotope (Sr, Nd, O) geochemistry of Cenozoic alkaline rift- type volcanic rocks from the Rohn area (central Germany): petrology, mantle source characteristics and implication for asthenospher interactions. Journal of volcanology and Geochemical Research, 27-53.
Jung, D., Kursten, M. and Tarkian, M., 1975 - Post Mesozoic Volcanism in Iran and its relation to the subduction of the Afro-Arabian under the Eurasian plate. In Pilger, A. and Rosler, A. (edts)"Afar between continental and oceanic Rifting "I.G.C.Scient.Report, 116(2), 175-181.
Kampunzu, A.B., Tombale, A.R. Zhai, M., Bagai, Z., Majaule, T. and Modisi, M.P., 2003- Major and trace element geochemistry of plutonic rocks from Francistown, NE Botswana: evidence for a Neoarchaean continental active margin in the Zimbabwe craton. Lithos, 71, 431-460
Karig, D.E., 1971- Origin and development of marginal basins in the Western Pacific. Journ. Geophys. Res., 76, 2542-2561.
Lescuyer, J.L. and Riou, R., 1979- Geologie de la region di Mineh (Azerbaidjan), Contribution a l'etude du Volcanisme tertiaire l'Iran. These de 3e me cycle. Grenoble. 233.
Maniar, P.D. and Piccoli, P.M., 1989- Tectonic discrimination of granitoides. Geol. Soc. Am. Bull. 101, 635-643.
Mcbirney, A.R. and Noyes, R.M., 1979- Crystallization and layering of the Skaergaard Intrusion. J. Pet., 20, 487-554.
Middlemost, E.A.K., 1985- Magmas and magmatic rocks. Longman, p 266.
Middlemost, E.A.K., 1991- Towards a comprehensive classification of Igneous rocks and magmas. Earth Sci. Rev, 31, 73-87.
Macdonald, R., Hawkesworth, C.J. and Heath, E., 2000- The Lesser Antilles Volcanic chain : a study in arc magmatism . Earth Science Reviews, 49, 1-76.
Moine-Vaziri, H., 1985- Volcanisme tertiaire et quaternaire en Iran. These d'Etat. Univer. Paris-Sud, ORSAY.
Nowroozi, A.A., 1971- Seismotectonics of the Persian plateau, Eastern Turkey, Caucasus and Hindu-Kush regions. Bull of the Seismological society of America, 61, 317-341.
Nelson, S.A., 2004 - Magmatic Differentition .Chemical variation in rock suites, EENS 212. Tulan University 15p.
Passhier, C.W. and Trouw, R.A.J., 1996 - Microtectonics, Springer, 286p.
Rollinson, H.R., 1993- Using geochemical data: evolution, presentation, interpretation. Jhon Wiley and sons, 325p.
Sabzehei, M., 1974 - Les mélanges ophiolitiques de la region d'Esfandagheh (Iran meridional). Etude petrographique et structurale. These Doct. Etat, Univ. Grenoble, 306p.
Shelly, D., 1993 - Igneous and metamorphic rocks under the microscope, Champan and Hall, 630p.
Takin, M., 1972 - Iranian geology and continental drift in the Middle East. Nature, 235, 147-150.
Wilson, M., 1989 - Igneous petrogenesis: a global tectonic approach. Unwin Hyman, London, 466P.
Weaver B.L. ,1991- Trace element evidence for the origin of ocean island basalts .Geology 19, 123-126.
Scientific Quarterly Journal of Geosciences
Volume 15, Issue 59
Spring 2006, Vol. 15, No.59
Spring 2006
Pages 162-175