%0 Conference Paper %F Oral %T Experimental characterization of heavy halogens behavior in alkaline magmas %+ Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO) %+ Magma - UMR7327 %A Faranda, Carmela %A Prouteau, Gaëlle %A Scaillet, Bruno %A Andújar, Joan %< avec comité de lecture %B Goldschmidt2021 %C Virtual, France %I European Association of Geochemistry %S Goldschmidt 2021 Abstract %8 2021-07-04 %D 2021 %R 10.7185/gold2021.7729 %Z Sciences of the Universe [physics] %Z Sciences of the Universe [physics]/Earth SciencesConference papers %X Halogens are minor volatile species emitted during volcaniceruptions, whose injection into the atmosphere contributes to thediminution of the stratospheric ozone layer and causes majorclimatic impacts. However, the lack of detailed understandingconcerning halogens behavior in magmas – especially bromineand iodine - and their degassing during magma ascent, prevents afull assessment of halogen cycling in the Earth’s system.Previous studies on iron-free synthetic systems have shown thatthe partitioning of Cl, Br and I between fluids and silicate meltsincreasingly favors the former as the ionic radii of the halogenideions increases [1]. These results suggest that bromine and iodinefluxes to the atmosphere are probably underestimated. Toevaluate this phenomenon, additional experimental constraints onBr and I behavior in natural magmas are urgently needed. In thisstudy, the Br partitioning between fluids and natural silicatemelts has been investigated experimentally as a function of meltcomposition, pressure, temperature and oxygen fugacity.Composition investigated and corresponding geodynamicsettings are representative of alkaline/hyperalkaline magmaticsystems worldwide. Experiments were performed in internallyheated pressure vessels (IHPV) under controlled oxygen fugacityand allowing drop quench. Bromine abundances weredetermined by μ-XRF, LA-ICP-MS or nanoSIMS, while fluidcomposition was estimated by mass balance calculations. Ourresults confirm the preference of bromine for the fluid phase,whatever the experimental conditions investigated, being inagreement with previous studies on metaluminous compositions[2], DBrf/m increasing with melt silica content. Due to its very lowconcentration in magmas, iodine behavior remains particularlypoorly known. To address this issue, we have carried out HP-HTsolubility experiments to synthesize a series of reference glasses,in order to test several sensitive analytical techniques for iodinequantification, such as LA-ICP-MS, nanoSIMS or neutronirradiation noble gas mass spectrometric technique. Dataacquired in this study will enrich a still fragmentary knowledgeof deep halogens geochemistry and therefore constitute part ofthe essential basis to develop the first physically-basedquantitative framework for volcanic heavy halogen emissions.[1] Bureau et al., (2000), Earth And Planetary Science Letters183, 51-60.[2] Cadoux et al., (2018), Earth And Planetary Science Letters498, 450–463. %G English %L insu-03477152 %U https://insu.hal.science/insu-03477152 %~ OBSPM %~ INSU %~ BRGM %~ CNRS %~ UNIV-ORLEANS %~ ISTO %~ OSUC %~ PSL %~ TEST-HALCNRS %~ OBSPM-PSL