Skip to main content Accessibility help

Mixing of basaltic and andesitic magmas in the Bazman volcanic field of southeastern Iran as inferred from plagioclase zoning

  • Zahra Firouzkouhi (a1), Ali Ahmadi (a1), David Richard Lentz (a2) and Ali-Asghar Moridi-Farimani (a1)


Late Cenozoic basalts of the Bazman volcanic field, Makran volcanic arc of southern Iran, contain two types of plagioclase feldspar phenocrysts with significant textural and compositional differences. The most common type is rather homogeneous with only weak zoning and maximum An content of 83 mol.%. The less common type of phenocryst exhibits complex zoning and, other than rims, is close in composition and similar in texture to those of associated andesites. This type of plagioclase phenocryst is characterized by an engulfed core with oscillatory zoning, which is overgrown by sieve-textured, moderately zoned mantle, and a relatively narrow rim. In both rock types, the An content of the core is between 40 and 63 mol.% with abrupt fluctuations. No significant correlation between An content and MgO, FeO, SrO and BaO is apparent in the core of phenocrysts in basalts. Anorthite content of the core of phenocrysts in andesites inversely correlates with SrO and BaO. The mantle of plagioclase phenocrysts in both rock types is characterized by sharp increases of An (up to 41 mol.%), MgO, and FeO, in the contact with the core. Anorthite correlates positively with MgO and FeO in the mantle, but correlation between An and SrO and BaO is not evident. It is assumed that plagioclase phenocrysts originally crystallizing from the host andesitic magma were interrupted by mixing with a hotter, juvenile basaltic magma. The resulting changes in temperature, composition, and H2O content of the surrounding melt caused compositional zonation, and the development of resorption in the cores and sieve texture in the mantles. As the An contents of the rims of the phenocrysts resemble the average An content of the groundmass plagioclases in both rock types, it is thought that the two involved magmas gained their independent physical identity before the formation of compositionally-distinct rims of plagioclase phenocrysts.


Corresponding author


Hide All
Anderson, A.T. (1976) Magma mixing: petrological process and volcanological tool. Journal of Volcanology and GeothermalResearch, 1, 333.
Arth, D. (1976) Behavior of trace elements during magmatic processes-a summary of theoretical models and their applications. Journal of Research of United States Geological Survey, 4, 858863.
Biabangard, H. and Moradian, A. (2008) Geology and geochemical evaluation of Taftan Volcano, Sistan and Baluchestan Province, southeast of Iran. Chinese Journal of Geochemistry, 27, 356369.
Churikova, T.G., Ivanov, B.V., Eichelberger, J., Worner, G., Browne, B. andIzbekov, P. (2013) Major and trace element zoning in plagioclase from Kizimen volcano (Kamchatka): insight into magma chamber processes. Journal of Volcanology and Seismology, 7, 112130.
Conrad, G., Montigny, R., Thuizat, R. and Westphal, M. (1981) Tertiary and Quaternary geodynamics of southern Lut (Iran) as deduced from palaeomagnetic, isotopic and structural data. Tectonophysics, 75, 1117.
Couch, S., Sparks, R.S.J. and Carroll, M.R. (2001) Mineral disequilibrium in lavas explained by convect-ive self-mixing in open magma chambers. Nature, 411, 10371039.
Dupuy, C. and Dostal, J. (1978) Geochemistry of calc-alkaline volcanic rocks from southeastern Iran (Kouh-e-Shahsavaran). Journal of Volcanology and Geothermal Research, 4, 363373.
Eichelberger, J.C., Chertkoff, D.G., Dreher, S.T. and Nye, C.J. (2000) Magmas in collision: Rethinking chemical zonation in silicic magmas. Geology, 28, 603606.
Ginibre, C., Kronz, A. and Worner, G. (2002) High-resolution quantitative imaging of plagioclase composition using accumulated backscattered electron images: new constraints on oscillatory zoning. Contributions to Mineralogy and Petrology, 142, 436448.
Ginibre, C. and Worner, G. (2007) Variable parent magmas and recharge regimes of the Parinacota magma system (N. Chile) revealed by Fe, Mg and Sr zoning in plagioclase. Lithos, 98, 118140.
Humphreys, M.C.S., Blundy, J.D. and Sparks, R.S.J. (2006) Magma evolution and open-system processes at Shiveluch volcano: Insights from phenocryst zoning. Journal of Petrology, 47, 23032334.
Jenner, G.A. (1996) Trace element Geochemistry of igneous rocks: geochemical nomenclature and analytical geochemistry. Pp. 5177 in: Trace Element Geochemistry of Volcanic Rocks: Applications for Massive Sulphide Exploration (Wyman, D.A., editor). Geological Association of Canada, Short Course Notes, 12, Winnipeg.
Kawamoto, T, (1992) Dusty and honeycomb plagioclase: indicators of processes in the Uchino stratified magma chamber, Izu Peninsula, Japan. Journal of Volcanology and Geothermal Research, 48, 191208.
Landi, P., Metrich, N., Bertagnini, A. and Rosi, M. (2004) Dynamics of magma mixing and degassing recorded in plagioclase at Stromboli (Aeolian Archipelago, Italy). Contributions to Mineralogy and Petrology, 147, 213227.
Lange, R.A, Frey, H.M. and Hector, J. (2010) A thermodynamic model for the plagioclase-liquid hygrometer/thermometer. American Mineralogist, 94, 494506.
Lee, C.T.A. and Bachmann, O. (2014) How important is the role of crystal fractionation in making andesitic magmas? Insight from Zr and P systematic. Earth and Planetary Science Letters, 393, 266274.
McCall, G.J.H. (1997) The geotectonic history of the Makran and adjacent areas of southern Iran. Journal of Asian Earth Sciences, 15, 517531.
Moinevaziri, H. (1985) Volcanism tertiar et quaternair en Iran. These d'Etat, Orsay University, Paris.
Nakamura, M. and Shimakita, S. (1998) Dissolution origin and syn-entrapment compositional change of melt inclusion in plagioclase. Earth and Planetary Science Letters, 161, 119131.
Nelson, S.T. and Montana, A. (1992) Sieve-textured plagioclase in volcanic rocks produced by rapid decompression. American Mineralogist, 77,12421249.
Pang, K.N., Chung, S.L., Zarrinkoub, M.H., Chiu, H.Y. and Hua, X. (2014) On the magmatic record of the Makran arc, southeastern Iran: Insights from zircon U-Pb geochronology and bulk-rock geochemistry. Geochemistry, Geophysics, Geosystems, 15, 21512169.
Perugini, D., Busa, T., Poli, G. and Nazzareni, S. (2003) The role of chaotic dynamics and flow fields in the development of disequilibrium textures in volcanic rocks. Journal of Petrology, 44, 733756.
Pringle, G.J., Trembath, L.T and Pajari, G.E. (1974) Crystallization history of a zoned plagioclase. Mineralogical Magazine, 39, 867877.
Putirka, K.A. (2005) Igneous thermometers and barometers based on plagioclase plus liquid equilibria: tests of some existing models and new calibrations. American Mineralogist, 90, 336346.
Ruprecht, P. and Worner, G. (2007) Variable regimes in magma systems documented in plagioclase zoning patterns:ElMististratovolcanoand Andahua monogenetic cones. Journal of Volcanology and Geothermal Research, 165, 142162.
Rutherford, M.J. and Devine, J.D. III (2008) Magmatic conditions and processes in the storage zone of the 2004-2006 Mount St. Helens dacite. Pp. 703725 in: A Volcano Rekindled: The Renewed Eruption of Mount St. Helens, 2004-2006 (D.R., Sherrod, W.E., Scott, and Stauffer, P.H., editors). U.S. Geological Survey Professional Paper, 1750. US Geological Survey, Reston, Virginia, USA.
Saadat, S. and Stern, C.R. (2011) Petrochemistry and genesis of olivine basalts from small monogenetic parasitic cones of Bazman stratovolcano, Makran arc, southeastern Iran. Lithos, 125, 607619.
Severs, M.J., Beard, J.S., Fedele, L., Hanchar, J.M., Mutchler, S.R. and Bodnar, R.J. (2009) Partitioning behavior of trace elements between dacitic melt and plagioclase, orthopyroxene, and clinopyroxene based on laser ablation ICPMS analysis of silicate melt inclusions. Geochimica et Cosmochimica Acta, 73, 21232143.
Shcherbakov, V.D., Plechov, P.Y., Izbekov, P.E. and Shipman, J.S. (2010) Plagioclase zoning as an indicator of magma processes at Bezymianny Volcano, Kamchatka. Contributions to Mineralogy and Petrology, 162, 8399.
Shore, M. and Fowler, D.A. (1996) Ossillatory zoning in minerals: a common phenomenon. The Canadian Mineralogist, 34, 11111126.
Singer, B., Dungan, M.A. and Layne, G.D. (1995) Textures and Sr, Ba, Mg, Fe, K and Ti compositional profiles in volcanic plagioclase: clues to the dynamics of calc-alkaline magma chambers. American Mineralogist, 80, 776798.
Snyder, D. and Tait, S. (1996) Magma mixing by convective entrainment. Nature, 379, 529531.
Stewart, M.L. and Pearce, T.H. (2004) Sieve-textured plagioclase in dacitic magma: Interference imaging results. American Mineralogist, 89, 348351.
Streck, M.J. (2008) Mineral textures and zoning as evidence for open system processes. Pp. 595622 in. Minerals, Inclusions and Volcanic Processes (Putirka, K.D. and Tepley, F.J. III, editors). Reviews in Mineralogy & Geochemistry, 69. Mineralogical Society of America and the Geochemical Society, Chantilly, Virginia, USA.
Tsuchiyama, A. (1985) Dissolution kinetics of plagioclase in the melt of the system diopside-albite-anorthite, and origin of dusty plagioclase in andesite. Contributions to Mineralogy and Petrology, 89, 116.
Vance, I A. (1965) Zoning in igneous plagioclase: patchy zoning. Journal of Geology, 73, 636651.
Viccaro, M., Giacomoni P.P., Ferlito, C. and Cristofolini, C. (2010) Dynamics of magma supply at Mt. Etna volcano (Southern Italy) as revealed by textural and compositional features of plagioclase phenocrysts. Lithos, 116, 7791.
Volynets, O.N., Popolitov, E.I., Flerov, G.B. and Kirsanov, I.T. (1977) Composition and geochemical characteristics of plagioclases from Quaternary volcanic rocks of Kamchatka and Kuril Islands. Geokhimiya, 5, 736747.
Williamson, B.J., Herrington, R.J. and Morris, A. (2016) Porphyry copper enrichment linked to excess aluminium in plagioclase. Naure Geoscience,
Zarifi, Z. (2006) Unusual subduction zones: case studies in Colombia and Iran. PhD Thesis, University of Bergen, Norway.
Zellmer, G.F., Blake, S., Vance, D., Hawkesworth, C. and Turner, S. (1999) Plagioclase residence times at two island arc volcanoes (Kameni Islands, Santorini, and Soufriere, St. Vincent) determined by Sr diffusion systematic. Contributions to Minerology and Petrology, 136, 345357.
Zhijian, N., Yue, L. and Yongjun, D. (2014) Plagioclase zoning as a record of magma evolution. Acta Geologica Sinica [English Edition], 88, 14771478.



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed