compositions of biotite from three different rock types of mashhad granitoids, i.e., granodiorite, monzogranite and leucogranite in ne of iran have been documented by electron microprobe and wet chemistry for fe3+ and fe2+. mashhad granitoids have been geochronologically and petrologically grouped into g1 and g2 phases. microprobe data show that the total fe contents in biotite from g2 leucogra...

Biotite dissolution rates were determined at 25 C, at pH 2–6, and as a function of mineral composition, grain size, and aqueous organic ligand concentration. Rates were measured using both openand closed-system reactors in fluids of constant ionic strength. Element release was non-stoichiometric and followed the general trend of Fe, Mg > Al > Si. Biotite surface area normalised dissolution rate...

Age Determination 105038 Kawano, Y. & Yuhara, M. Chronological and isotope geological study of Cretaceous granitic rocks, upper reach of the Nakagawa river, Fukuoka Prefecture. J. Geol. Soc. Japan, 114, 218-230, 8 figs., 2 tables (in Japanese with English abstract), 2008. Cretaceous granitic rocks, consisting of Itoshima granodiorite and Sawara granite, are occurred at upper reach of the Nakaga...

Our understanding of frictional melting that occurs during large earthquake slip events has been hampered by the extremely fine-grain size of frictionally fused rock, and the lack of detailed high-resolution microscopy studies that describe features at the crystal lattice scale. In such a study, we here report the complex nature of melting and crystallization in a symmetrically layered, pseudot...

Abiotic nitrogen reduction (ANR) in hydrothermal systems has been long considered as the most likely mechanism to transform N2, the dominant N species on the pre-life Earth’s surface, into NH4+, an essential compound for abiotic synthesis of large organic molecules facilitating the emergence of life in the early oceans [1]. Mineral-induced ANR process has been demonstrated by laboratory experim...

studies of three selected sulfide-silicate assemblages from ore samples from the sar cheshmeh porphyry copper deposit led to some ore genetic conclusions. the presence of chalcopyrite blebs in the groundmass orthoclase and quartz from the stock suggests liquid immiscibility in a cooling late-magmatic melt. this is in favor of the orthomagmatic model proposed for porphyry copper deposits. the pr...

Laser confocal differential interference contrast microscopy (LCM-DIM) allows for the study of the reactivity of surface minerals with slow dissolution rates (e.g., phyllosilicates). With this technique, it is possible to carry out in situ inspection of the reacting surface in a broad range of pH, ionic strength and temperature providing useful information to help unravel the dissolution mechan...

the arghash area is located 45 km to southwest of neyshabour. the subvolcanic rocks in the area consist of biotite hornblende quartz monzodiorite porphyry, hornblende biotite quartz monzodiorite porphyry, hornblende monzonite porphyry, biotite hornblende monzonite porphyry, monzodiorite porphyry and biotite quartz monzodiorite porphyry units. the volcanic rocks consist of hornblende biotite dac...