Estimation of pre-eruptive magmatic water fugacity in the Phlegrean Fields, Naples, Italy
نویسندگان
چکیده
We estimated the water fugacity (f H2O) in the trachytic magma of Phlegrean Fields using the biotite–magnetite–sanidine equilibrium. We confirm that the partly ionic model is the most appropriate to estimate annite activity (aannite) for the experimental biotite. Crystallization experiments were carried out on a representative sample of trachytic Breccia Museo eruption, Naples, Italy. Experiments were performed in the temperature and pressure range of 725–870 °C and 50–200 MPa, and redox conditions ranging from NNO (nickel–nickel oxide) + 1 (±0.2) to FMQ (fayalite + magnetite + quartz). Most experiments were done under conditions of H2O saturation (Pwater = Ptotal). Few experiments were done using a mixed H2O–CO2 fluid phase. The pre-eruptive fH2O of the Phlegrean Fields magma is estimated at 735 bars, which compares well with available melt inclusion constraints. Our results confirm that this geohygrometer can be used in any magmatic systems bearing the worked assemblage. Key-words: crystallization experiments, geohygrometer, trachytic magmas, water fugacity.
منابع مشابه
Estimation of the Methane Emission Factor for Buffalo Cattle and Bulls
In order to determine the incidence of buffaloes on enteric CH4 emissions, information about animal production and farm management was analyzed and the CH4 emission factor estimated using the IPCC Tier 2 model. CH4 emission factor for the category of buffalo cattle and buffalo bulls was estimated for the period 2000-2007, in Italy, Europe and worldwide. During 2007, the CH4 emission factor for ...
متن کاملWater and the oxidation state of subduction zone magmas.
Mantle oxygen fugacity exerts a primary control on mass exchange between Earth's surface and interior at subduction zones, but the major factors controlling mantle oxygen fugacity (such as volatiles and phase assemblages) and how tectonic cycles drive its secular evolution are still debated. We present integrated measurements of redox-sensitive ratios of oxidized iron to total iron (Fe3+/SigmaF...
متن کاملPre-eruptive magmatic processes re-timed using a non-isothermal approach to magma chamber dynamics
Constraining the timescales of pre-eruptive magmatic processes in active volcanic systems is paramount to understand magma chamber dynamics and the triggers for volcanic eruptions. Temporal information of magmatic processes is locked within the chemical zoning profiles of crystals but can be accessed by means of elemental diffusion chronometry. Mineral compositional zoning testifies to the occu...
متن کاملDefining Robust Recovery Solutions for Preserving Service Quality during Rail/Metro Systems Failure
In this paper, we propose a sensitivity analysis for evaluating the effectiveness of recovery solutions in the case of disturbed rail operations. Indeed, when failures or breakdowns occur during daily service, new strategies have to be implemented so as to react appropriately and re-establish ordinary conditions as rapidly as possible. In this context, the use of rail simulation is vital: for e...
متن کامل