Chemical Composition, Petrology and P-T Conditions of Ti-Mg-Biotites within Syenitic Rocks from the Lar Igneous Suite, East of Iran
The Lar Igneous Suite (LIS), east of Iran, is part of post collisional alkaline magmatism related to Late Cretaceous- mid Eocene Sistan suture zone. The suite consists of a wide variety of igneous rocks, from volcanic to intrusive and hypabissal rocks such as tuffs, trachyte, monzonite, syenites and lamprophyres. Syenitic rocks which mainly occur in a giant ring dike and stocks, are shoshonitic to potassic-ultrapotassic (K2O/Na2O > 2 wt.%; MgO > 3 wt.%; K2O > 3 wt.%) in composition and are also associated with Cu-Mo mineralization. In this study, chemical composition of biotites within the Lar syenites (LS) is determined by electron microprobe analysis. The results show that LS biotites are Ti-Mg-biotites (phlogopite) which contain relatively high Ti and Mg, and low Fe concentrations. The Mg/(Fe2++ Mg) ratio in these biotites range between 0.56 and 0.73 that represent their transitionally chemical evolution. TiO2 content in these biotites is high and in the range of 3.0-5.4 wt.%. These chemical characteristics indicate that the LS biotites are primary and have been crystallized directly from magma. The investigations also demonstrate that the LS biotites have crystallized from a magma of orogenic nature. Temperature and pressure are the most significant factors controlling Mg and Ti content in the LS biotites, respectively. The results show that the LS biotites crystallized at temperatures (T) between 800 to 842 °C and pressures (P) between 0.99 to 1.44 kbar. These conditions are indicative of a crystallization depth of 3.26-4.74 km.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.3346712Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 193
 Labotka, T. C., (1983). Analysis of the compositional variations of biotite in pelitic hornfelses from northeastern Minnesota. American Mineralogist, 68, 900-914.
 Speer, J. A., (1984). Micas in igneous rocks. In: Micas. Bailey S.W., (Eds.). Review of Mineralogy, 13: 299-356.
 Wones, D. R, Eugester, H. P., (1965). Stability of biotite: experiment, theory, and application. American Mineralogist, 50, 1228-1272.
 Nachit, H., Razafimahefa, N., Stussi, J. M., Carron, J. P., (1985). Composition chimique des biotites et typologie magmatique des granitoids, Comtes Rendus Hebdomadaires de l’ Academie des Sciences 301, 11, 813–818.
 Patiño Douce, A. E, (1993). Titanium substitution in biotite: an empirical model with applications to thermometry, O2 and H2O barometries, and consequences form biotite stability. Chemical Geology, 108, 133.162.
 Boomeri, M., Mizuta, T., Ishiyama, D., Nakashima, K., (2006). Fluorine and chlorine in biotite from the Sarnowsar granitic rocks, Northeastern Iran. Iranian Journal of Science & Technology, Transaction A, 30, A1, 111-125.
 Müller, D., Groves, D. I., (2016). Potassic Igneous Rocks and Associated Gold-Copper Mineralization. 4th edn. Springer- Mineral Resource Reviews, USA, 342p.
 Henry, D. J., Guidotti, C. V., Thomoson. J. A., (2005). The Ti-saturation surface for low-to-medium pressure metapelitic biotites: implications for geothermonmetry and Ti-substitution mechanisms. American Mineralogist, 90, 316-328.
 Dong, Q., Du, Y., Pang, Z., Miao, W., Tu, W., (2014). Composition of biotite within the Wushan granodiorite, Jiangxi Province, China: Petrogenetic and metallogenetic implications. Earth Sciences Research Journal, 18, 1, 39 – 44.
 Richards, J. P., (2015). Tectonic, magmatic, and metallogenic evolution of the Tethyan orogen: From subduction to collision. Ore Geology Reviews, 323-345.
 Richards, J. P., Spell, T., Rameh, E., Razique, A., Fletcher, T., (2012). High Sr/Y magmas reflect arc maturity, high magmatic water content, and porphyry Cu ± Mo ± Au potential: examples from the Tethyan arcs of central and eastern Iran and western Pakistan. Economic Geology, 107, 295–332.
 Asiabanha, A., Foden, J., (2012). Post-collisional transition from an extensional volcanosedimentary basin to a continental arc in the Alborz Ranges, N-Iran. Lithos 148, 98–111.
 Ghafaribijar, S., (2009). Geochemistry of Potassic Mafic Rocks in the Lar Complex, North of Zahedan, East of Iran, M.Sc. Thesis, Sistan and Baluchestan Univ.
 Pang, K. N., Chung, S. L., Zarrinkoub, M. H., Khatib, M. M., Mohammadi, S. S., Chiu, H. Y., Chu, C. H., Lee, H. Y. and Lo, C. H., (2013). Eocene–Oligocene post-collisional magmatism in the Lut–Sistan region, eastern Iran: Magma genesis and tectonic implications. Lithos, 180- 181, 234-251.
 Stone, D., (2000). Temperature and pressure variations in suites of Archean felsic plutonic rocks, Berens river area, northwest superior province, Ontario, Cananda. The Canadian Mineralogist, 38, 455-470.
 Deer W. A., Howie A., Zussman J., (1986). An interdiction to rock- forming minerals. 17th edn. Longman Ltd, 528p.
 Abdel-Rahman, A. M., (1994). Nature of biotites from alkaline, calc-alkaline, and peraluminous magmas, Journal of Petrology, 35, 2, 525– 541.
 Foley, S. F., Venturelli, G., Green, D. H., Toscani, L., (1987). The ultrapotassic rocks: characteristics, classification, and constraints for petrogenetic models. Earth-Sciences Reviews, 24, 81-134.
 Engel, A. E. J., Engel, C. G., (1960). Progressive metamorphism and granitization of the major paragneiss, northwest Adirondack Mountains, New York, Part 2. Mineralogy. Bulletin of the Geological Society of America, 71, 1.58.
 Kwak, T. A. P., (1968). Ti in biotite and muscovite as an indication of metamorphic grade in almandine amphibolite facies rocks from Sudbury, Ontario. Geochimica et Cosmochimica Acta, 32, 1222.1229.
 Robert, J. L, (1976). Titanium solubility in synthetic phlogopite solid solutions. Chemical Geology, 17, 213.227.
 Dymek, R. F., (1983). Titanium, aluminum and interlayer cation substitutions in biotite from high-grade gneisses, West Green land. American Mineralogist, 68, 880.899.
 Guidotti, C. V., Sassi, F. P., (2002). Constraints on studies of metamorphic K-Na white micas. In A. Mottana, F.P. Sassi, J.B. Thompson Jr., and S. Guggenheim, Eds., Micas: Crystal Chemistry and Metamorphic Petrology, 46, 419.448. Reviews in Mineralogy and Geochemistry, Mineralogical Society of America, Washington, D. C.
 Henry, D. J., and Guidotti, C. V., (2002). Ti in biotite from metapelitic rocks: Temperature effects, crystallochemical controls and petrologic applications. American Mineralogist, 87, 375.382.
 Uchida, E., Endo, S., Makino, M., (2007). Relationship between solidification depth of granitic rocks and formation of hydrothermal ore deposits. Resource Geology, 57, 1, 47-56.
 Arima, M., Edgar, A. D., (1981). Substitution mechanisms and solubility of titanium in phlogopites from rocks of probable mantle origin. Contributions to Mineralogy and Petrology, 77, 288-295.
 Tronnes, R. G., Edgar, A. D., Arima, M., (1985). A high pressure-high temperature study of TiO2 solubility in Mg-rich phlogopite: Implications to phlogopite chemistry. Geochimica et Cosmochimica Acta, 49, 2323.2329.