Petrography and geochemistry of mylonitic granite from Ghaleh-Dezh, NW Azna, Sanandaj-Sirjan zone, Iran

作者：Shabanian Nahid^*; Khalili Mahmoud; Davoudian Ali Reza; Mohajjel Mohammad

来源：Neues Jahrbuch für Mineralogie - Abhandlungen, 2009, 185(3): 233-248.

DOI：10.1127/0077-7757/2009/0121

• A-type granite
• post-collisional
• shear zone
• Sanandaj-Sirjan
• Iran

We have carried out a petrographic and geochemical investigation of the Ghaleh-Dezh granitic pluton in southwestern Iran. Petrographic studies show mylonitic fabrics and microstructures in these rocks. Asymmetrical core-and-mantle structure is the most characteristic fabric in these rocks. The Ghaleh-Dezh mylonitic granite is generally coarse-rained, contains mainly quartz, alkali feldspar, plagioclase, biotite and Muscovite. Based on collected geochemical data, the granites have a pronounced A-type affinity: they are mostly metaluminous with high concentrations of Na(2)O+K(2)O, Rb, HFSE, REE (except Eu), high K(2)O/Na(2)O and Fe/(Fe+Mg) ratios, and very low concentrations of MgO, CaO, P(2)O(5), and Sr. Moreover, the granites plot in the range of post-collision granites and belong to the A2-type. The decreasing concentrations of Al(2)O(3), TiO(2), Zr, Sr, Ba and, maybe Ga with increasing SiO(2) may be related to fractional crystallization of mainly biotite, K-feldspar, plagioclase, titanite and zircon. Based on the isotope data (Rb-Sr and Sm-Nd), the Ghaleh-Dezh plutonic rocks are derived from a mantle source with the magma undergoing coupled crustal assimilation-fractionation during uprising through continental crust.

• 出版日期2009-4