in the centeral iranian volcanic belt (civb), north-west of shahre-babak, in area of javazm, dehaj and khabr, about 20 plutonic porphyritic tonalitic to granodioritic masses (1-50 km2) are intruded into a varity of rock sequences from eocene to early miocene in age. tonalitic and granodioritic rocks are some part of dehaj-sardoieh belt and having early miocene age. the civb contains intrusive a...

Isotopic ratios and concentrations of the alkaline earth metals Mg and Sr in biogenic calcite are of great importance as proxies for environmental parameters. In particular, the Mg /Ca ratio as a temperature proxy has had considerable success. It is often hard to determine, however, which parameter ultimately controls the concentration of these elements in calcite. Here, multiple Mg /Ca and Sr ...

Fractionation of isotopes among distinct molecules or phases is a quantum effect which is often exploited to obtain insights on reaction mechanisms, biochemical, geochemical, and atmospheric phenomena. Accurate evaluation of isotope ratios in atomistic simulations is challenging, because one needs to perform a thermodynamic integration with respect to the isotope mass, along with time-consuming...

Anomalously high platinum group element concentrations have previously been reported for Upper Triassic deep-sea sediments, which are interpreted to be derived from an extraterrestrial impact event. Here we report the osmium (Os) isotope fingerprint of an extraterrestrial impact from Upper Triassic chert successions in Japan. Os isotope data exhibit a marked negative excursion from an initial O...

Future missions to Venus will require a focused investigation of the atmospheric composition, to complete the story of its formation and evolution drafted by the probes of the 1970s and 1980s and developed further by recent missions such as Venus Express. Priority measurements include the mixing ratios and isotope ratios of all noble gases, detection of trace species in the lower atmosphere inc...

the lalezar granitoids crop out within volcanic successions of the urumieh-dokhtar magmatic assemblage (udma). these granitoids have a range from gabbro-diorites to granites in composition. the mineral compositions of the most felsic rocks are characterized by the abundances of na-plagioclase, quartz, alkali feldspar, biotite and hornblende. in the gabbro-diorite rocks, plagioclase (ca-rich), h...

the igneous dykes are a small mafic rock unit exposed in the south gorgan of eastern alborz, north iran. these mafic dykes are intruded in the middle–upper paleozoic sedimentary and metamorphic rocks units representing a part of the north gondwana province. the studied samples were collected from various locations along the exposed bodies. thin sections of these rocks show medium to coarse grai...

In the eastern Grand Canyon, secondary porosity created by north trending faults, folds, and breccia pipes, facilitates groundwater flow through the South Rim carbonate aquifer. Springs associated with the South Rim Aquifer have low H concentrations, [Ca']/[Mg '] ratios close to unity, and variable uranium concentrations. For a geochemical comparison, springs are subcategorized on the basis of ...