Tourmaline composition of Chah rouii pegmatites, southwest of Nehbandan

Abstract

The Chah ruii area in southwest of Nehbandan contains two types of tourmaline pegmatites. Type one (type CH) pegmatites are found in the granitoid body and type two (type D) pegmatites in metamorphic rocks around the granitoid. Based on petrography and electron microprobe analyses these tourmalines show schorl- dravite, and located in alkali groups and have high Al contents and deprotonation-substitution and alkali- substitution. The spider and REE diagrams in tourmaline indicate that both groups have similar patterns but the  rate of trace elements are different, and the reason for  more rate of trace elements in tourmaline CH type are setting in granitoid rocks. Then, based on analytical studies, it appears that tourmalines form by interaction of postmagmatic/ residual or hydrothermal fluids related to Chah ruii granitic magma with Deh Salm metamorphic rocks. Temprature variations in formation of mineral types in the pegmatites are very important.

Keywords


[1] نادری میقان ن.، "نقشه: 1:100000چاه داشی"، سازمان زمین شناسی و اکتشافات معدنی کشور، (شهریور1383).

]2[ Burinnek D., Novak M., "Compositional evolution and substitutions in disseminated and nodular tourmaline from leucocratic granites: Example from the Bohemian Massif, Czech", Republic. Lithos, inpres (2006).

]3 [Jiang S.Y., Palmer M.R., Christopher J.Y., "Chemical and boron isotopic compositions of tourmaline from the Archean Big Bell and Mount Gibson gold deposits", Murchison Province, Yilgarn Craton, Western Australia. Chemical Geology 188, (2002) 229– 247.

]4[ Keller P., Roda E., Pesquera A., Fontan F., "Chemistry, paragenesis and significance of tourmaline in pegmatites of the Southern Tin Belt", central Namibia, Chemical Geology 158, (1999) 203–225.

]5[ Dutrow B., Henry D. J., "Complexly zoned fibrous tourmaline: A record of evolving magmatic and hydrothermal fluids", Canadian Mineralogist,Vol 38, (2000) 131-143.

]6 [ Hawthorne F. C., "Bond – valence constraints on thechemical composition of tourmaline", Can. Mineral, Vol 40, (2002) 789 -797.

]7[ Henry D. J., Dutrow B. L., "Metamorphic tourmaline and its petrologic applications", In: Grew, E.S, Anovitz, L.M., (Eds.), Boron: Mineralogy, Petrology, and Geochemistry, Reviews in Mineralogy. Vol 33, (1996) 503– 557.

]8[ Hawthorne F. J., Henry D. J., "Classification of the minerals of thetourmaline group". European Journal of Mineralogy.Vol 11,( 1999) 201- 216..

]9[ London D., Manning D.A.C., "Chemical variation and significance of tourmaline from Southwest England", Economic Geology,Vol 90, (1995) 495– 519.

]10[ Nakamura N., "Determination of REE, Ba, Fe, Mg, Na and K in carbonaceous and ordinary chondrites", Geochim, Cosmochim, Acta 38, (1974) 757- 775.

]11[ King R.W., Kerrich R., "Chromian dravite associated with ultramafic-rock-hosted Archean lode gold deposits", Timmins–Porcupine district, Ontario, Canad Mineral 27, (1989) 419–426.

]12[ Henry D. J., Guidotti C.V., "Tourmaline as a petrogenetic indicatormineral: an example from the staurolite- grade metapelites of NW Maine", American Mineralogist, Vol 70, (1985) 1-15.

]13[ Grew, E. S., Anovitz, L. M., "Boron mineralogy, petrology and geochemistry", Reviews in mineralogy, 1st, 33p (1997).

]14[ Thompson R.N., "British Tertiary volcanic province", Scott, J., Geol, Vol 18, (1982) 49-107.

]15[ Trumbull, R. B., Chaussidon, M., "Chemical and boron isotopic composition of magmatic and hydrothermal tourmaline from the Sinceni granite- pegmatite system in Swaziland", Chemical geology, 153(1999)125-137.