volcanic rocks of interest are situated in the middle part of the urumieh-dokhtar magmatic arc (udma). they are parts of a vast magmatic province located in the north of bitlis-zagros suture zone. having a prevailing porphyritic texture, these rocks include phenocrysts of plagioclase, amphibole and biotite in a matrix composed of feldspar, quartz, opaque, glass and microlite and mineralogically...

biotite samples from different units of boroujerd granitoid complex (bgc) of the sanandaj-sirjan zone, western iran, have beenanalyzed by electron microprobe for major elements. biotite analyses from three units of quartzdiorite, granodiorite and monzograniteof bgc have their own distinct non-overlapping compositional fields in the annite – siderophyllite – phlogopite – eastonitequadrilateral (...

We report the results of an experimental calibration of oxygen isotope fractionation between quartz and zircon. Data were collected from 700 to 1000 C, 10–20 kbar, and in some experiments the oxygen fugacity was buffered at the fayalite–magnetite–quartz equilibrium. Oxygen isotope fractionation shows no clear dependence on oxygen fugacity or pressure. Unexpectedly, some high-temperature data (9...

Martian surface can be accounted for by two methods of production; photolysis of water molecules via solar ultraviolet light, releasing hydrogen and oxidising iron, and, the residual effects of the addition of biogenic redox products. We can estimate the amount of Fe 3+ created by photodissociated oxygen by observing the primordial and current redox states of Mars. This is conducted via calcula...

A new method is developed to control water fugacity at a fixed pressure and temperature. We use two divariant phase assemblages (clinohumite–periclase–forsterite and brucite–periclase) in the MgO– SiO2–H2O system and the chemical reactions among co-existing phases buffer the water fugacity. In order to avoid a reaction between the water fugacity buffer and the specimen, a double-capsule assembl...

biotite samples from different units of boroujerd granitoid complex (bgc) of the sanandaj-sirjan zone, western iran, have beenanalyzed by electron microprobe for major elements. biotite analyses from three units of quartzdiorite, granodiorite and monzograniteof bgc have their own distinct non-overlapping compositional fields in the annite – siderophyllite – phlogopite – eastonitequadrilateral (...

Written by G. Jeffrey Taylor Hawai'i Institute of Geophysics and Planetology Studies have inferred that the oxidation state of Martian basaltic meteorites (the shergottites) is correlated with diagnostic geochemical parameters. For example, Meenakshi Wadhwa (Field Museum, Chicago) showed that as the ratio of triply-charged europium to doubly-charged europium (Eu3+/Eu2+) increases in a group of ...

High-pressure oxygen fugacity (‘redox’) sensors are widely used to make estimates of the effective concentration of oxygen in experimental petrology. They typically rely on iron either diffusing into a nominally iron free mineral (e.g. iron into magnesiowüstite [1]) or iron alloying with a noble metal[2, 3]. In both cases the iron content of the sensor material should reflect the prevailing oxy...

This paper describes the development and application of a novel method for the measurement of grain boundary electrical conductivity of rock at high temperature and pressure. In this method, the metal electrodes, the corresponding metal shielding case, and the sleeves are altered in order to appropriately adjust and monitor the oxygen fugacity in a sample cavity in a high-pressure apparatus. As...