Original paper

Peraluminous two mica leucogranite of the Aderba Pluton, NE Golpayegan, Iran: Hydrogen isotope and chemistry of biotite significance

Mirlohi, Akramosadat; Khalili, Mahmoud; Esfahani, Mahin Mansouri; Manesh, Seyed Mohsen Tabatabaei

Abstract

The Aderba leucogranite forms a part of the Golpayegan metamorphic complex in the Sanandaj-Sirjan Zone and is mainly composed of quartz, alkali-feldspar, plagioclase and biotite (as the dominant ferromagnesian mineral), with subordinate amounts of muscovite, zircon, chlorite and sericite. The investigated Fe and Al biotites of the leucogranite have peraluminous character. Magma redox conditions based on the biotite composition place the Aderba leucogranite within the ilmenite series granitic rocks and reduced S-type granitoids, which is derived from a peraluminous magma via anatexis of metasedimentary rocks during a syn-collisional event. Biotite hydrogen isotope compositions have δD values ranging from -66‰ to -77‰ that are similar to those of the igneous biotites. The δ D values indicate a high temperature deformation of the Aderba leucogranite pluton with no influence of an external (meteoric) fluid. Furthermore, the average δD value of the Aderba leucogranite (-64.4‰) demonstrates its S-type affinity.

Keywords

iransanandaj-sirjan zoneilmenite series granitic rocksleucogranitehydrogen isotopebiotite