Amphibole Chemistry in Low–temperature I–type Granites from Kashmar Area, Northeastern Central Iran Plate (CIP)

Abstract

The Kashmar granitoid (43.5–42.4 Ma) forms an extensive part of iron–oxide type magmatic belt in northern side of the Doruneh Fault. It includes plutons of tonalite, granodiorite, granite and alkali feldspar granite which are metaluminous (ASI ≤ 1) in nature. They contain dominantly felsic minerals, representing I–type granites with low–temperature and low–pressure characteristics. According to microscopic studies and electron microprobe analyses, all amphiboles in Kashmar are monoclinic calcic hornblende which is common mafic mineral in distinction of I–type granites. The calculated structural formula for Kashmar amphiboles show characteristics of magnesio-hornblende as follow:

They are low in Al2O3 and TiO2, high in Mg* (0.6–0.75), extremely low in AlVI (<0.1 apfu) but significantly higher in Fe3+, features indicating low temperature, low pressure and oxidized conditions. Using appropriate thermo barometers for Kashmar amphiboles, average temperature of 650 oC, pressures of ≤ 3 kb and logfO2 = –16.59 to –19.40 were calculated. These results define a thermal boundary of ~700 oC between felsic and mafic low–temperature I–type granites.

Keywords

References

[1] Soltani A. ″Geochemistry and geochronology of I–type granitoid rocks in the northeastern Central Iran Plate″, PhD Thesis, University of Wollongong, Australia (unpubl.), (2000) 300 p.

[2] Robinson P., Spear F. S., Schumbacher J. C., Laird J., Klein C., Evans B. W., Doolan B. L., ″Phase relations of metamorphic amphiboles: natural occurrence and theory″, In Veblen D. R. & Ribbe P. H. (eds). Amphiboles: Petrology and Experimental Phase Relations, Mineralogical Society of America, Review in Mineralogy, 9B: (1982) pp. 1–227.

[3] Leake B. E., Woolley A. R., Arps C. E. S., Birch W. D., Hawthorne F. C., Kato A., Kisch H. J., Krivovichev V. G., Linthout K., Laird J. Mandarino J. A., Maresch W. V., Nikel E. H., Rock N. M. S., Schumacher J. C., Smith D. C., Stephen N. C. N., Ungaretti L., Whittaker E. J. W., and Youzhi G., ″Nomenclature of amphiboles″, Report of the Subcommittee on Amphiboles of the International Mineralogical Association, Commission on New Minerals and Mineral Names. American Mineralogist, v. 82, (1997) pp. 1019–1037.

[4] Leake B. E., Woolley A. R., Birch W. D., Burke E. A. J., Feraris G., Grice J. D., Hawthorne F. C., Kisch H. J., Kerivovichev V. J., Schumacher J. C., Stephenson N. C. N., Whittaker J. W., ″Nomenclature of amphiboles″, Additions and revisions to the International Mineralogical Association’s amphibole nomenclature. American Mineralogist, v. 89, (2004) pp. 883–887.

[5] Hammarstrom J. M., Zen E., ″Aluminum in hornblende″, An empirical igneous geobarometer. American Mineralogist, v. 71, (1986) pp. 1297–1331.

[6] Johnson M. C., Rutherford M. J., ″Experimentally calibration of the aluminum–in–hornblende geobarometer with application to Long Valley caldera (California) volcanic rocks″, Geology, v. 17, (1989) pp. 837–841.

[7] Gribble C. D., ″Rutley’s Elements of Mineralogy″. 27th editions, Unwin Hyman, London (1988).

[8] Anderson J. L., Smith D. R., ″The effect of temperature and fO2 on the Al–in–hornblende barometer″, American Mineralogist, v. 80, (1995) pp. 549–559.

[9] Schmidt M. W., ″Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al–in–hornblende barometer″, Contribution to Mineralogy and Petrology, v. 110, (1992) pp. 304–310.

[10] Al’meev R. R., Ariskin A. A., Yu. Ozerov A., Kononkova N. N., ″Problems of the stoichiometry and thermobarometry of magmatic amphiboles″, An example of hornblende from the andesites of Bezymyannyi Volcano, eastern Kamchatka, Geochemistry International, v. 40, No. 8 (2002) pp. 723-738.

[11] Bachmann O., Dungan M. A., ″Temperature–induced Al–zoning in hornblendes of the Fish Canyon magma, Colorado″, American Mineralogist, v. 87, (2002) pp.1062–1076.

[12] Wones D. R., ″Significance of the assemblage titanite + magnetite + quartz in granitic rocks″, American Mineralogist, v. 74, (1989) pp. 744–749.

[13] Holland T., Blundy J., ″Non–ideal interactions in calcic amphiboles and their bearing on amphibole–plagioclase thermometry″, Contribution to Mineralogy and Petrology, v. 116, (1994) pp. 433–447.

[14] Stone D., ″Temperature and pressure variations in suites of Archean felsic plutonic rocks, Berens River Area, northwest superior province, Ontario, Canada″, The Canadian Mineralogist, v. 38, (2000) pp. 455–470.

[15] Burkhard D. J. M., ″Temperature and redox path of biotite–bearing intrusives: a method of estimation applied to S– and I–type granites from Australia″, Earth and Planetary Science letters, v. 104, (1991) pp. 89–98.

[16a] Chappell B. W., ″High– and Low–temperature Granites″, The Ishihara Symposium: Granites and Associated Metallogenesis, GEMOC, Macquarie University, NSW, 2010, Australia, (2004) pp. 43.

[16b] Chappell B. W., ″Towards a unified model for granite genesis″, Transactions of the Royal Society of Edinburgh: Earth Sciences, v. 95, (2004) pp.1-10.

[17] Anderson J. L., ″Regional tilt of the Mount Stuart Batholith, Washington, determined using Al–in–hornblende barometry″, Implications for northward translation of Baja British Columbia: Discussion and Reply. Geological Society of America Bulletin, v. 109, (1997) pp. 1223–1227.

[18] Karimpour M. H., Malekzadeh A., ″Comparison of the geochemistry of source rocks at Tannurjeh Au–bearing magnetite and Sangan Au–free magnetite deposits, Khorasan Razavi, Iran″, Iranian Journal of Crystallography and Mineralogy, No. 1, (2006), pp. 3–26.

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History

  • Receive Date: 02 July 2025
  • Revise Date: 04 February 2026
  • Accept Date: 02 July 2025

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