Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2

Potential flank eruptions at the presently active Villarrica, Southern Andes Volcanic Zone (33.3–46 °S) require the drawing of a comprehensive scenario of eruptive style dynamics, which partially depends on the degassing process. The case we consider in this study is from the Los Nevados Subgroup 2 (LNG2) and constitutes post-glacial minor eruptive centers (MECs) of basaltic–andesitic and basaltic composition, associated with the northeastern Villarrica flank. Petrological studies of the melt inclusions volatile content in olivine determined the pre-eruptive conditions of the shallow magma feeding system (<249 Mpa saturation pressure, 927–1201 °C). The volatile saturation model on “pressure-dependent” volatile species, measured by Fourier Transform Infrared Microspectrometry (FTIR) (H2O of 0.4–3.0 wt.% and CO2 of 114–1586 ppm) and electron microprobe (EMP), revealed that fast cooling pyroclasts like vesicular scoria preserve a ~1.5 times larger amount of CO2, S, Cl, and volatile species contained in melt inclusions from primitive olivine (Fo76–86). Evidence from geological mapping and drone surveys demonstrated the eruption chronology and spatial changes in eruption style from all the local vents along a N45° corridor. The mechanism by which LNG2 is degassed plays a critical role in increasing the explosivity uphill on the Villarrica flank from volcanic vents in the NE sector (<9 km minimum saturation depth) to the SW sector (<8.1 km), where many crystalline ballistic bombs were expulsed, rather than vesicular and spatter scoria.

Modeling volatile species in magma ocean-atmosphere interactions on hot rockyexoplanets

&lt;p&gt;Hot rocky exoplanets present us with the unique opportunity to give us insights into their interiors through the characterization of their atmospheres. With the upcoming launch of the JWST and ARIEL ushering in a new era of exoplanet observations, this topic is becoming more relevant than ever.&amp;#160;&lt;/p&gt; &lt;p&gt;A crucial element in this work is the accurate modeling of the interaction between planetary atmospheres and their magma oceans. The key question here being: What is the atmospheric composition of a hot rocky exoplanet for a given magma ocean composition? One pressing issue one must face when answering this question is the inclusion of volatile species (such as H2, H2O, CO2, etc.). Currently, hot rocky exoplanets are often assumed to be entirely depleted of volatile species, or simplified models are applied in which but a few species in both the melt and the atmosphere are taken into account.&lt;/p&gt; &lt;p&gt;In this presentation we will show our ongoing work on including volatiles species in the modeling of magma ocean-atmosphere interactions on hot rocky exoplanets. The successful development of this method and subsequent comparisons to observations would allow us to start characterising rocky exoplanet compositions which could lead to new insights for formation models. Furthermore, it would also allow us to model the effects of transient magma oceans though to be present on young earth analogs. Deepening our understanding of how such processes influence the conditions present during later evolutionary stages could give us new insights in the evolution of the earth and the conditions necessary to sustain life.&lt;/p&gt;

Clathrate hydrates FTIR spectroscopy to understand cometary ices

&lt;p&gt;Comet nuclei in the transneptunian region are submitted to&amp;#160; heating at temperatures from 30 to 50 K over the age of the solar system [1]. The timescale for sublimated volatiles to escape the objects at these temperatures is long though [1]. Once these nuclei enter the inner solar system and become active, subsurface sublimation puts a gas phase in contact of the porous and tortuous ice structure of cometary material. In this context, the formation of clathrate hydrates may be considered as a plausible trapping mechanism of these gases, occurring in subsurface layers, and allowing some of the most volatile species to subsequently survive in cometary material at temperatures higher than the sublimation temperature of the corresponding pure solid [2].&amp;#160;&lt;/p&gt; &lt;p&gt;Hydrates are ice-like crystalline compounds, resulting from the tridimensional stacking of cages of H-bonded water molecules. Clathrates are gas hydrates, meaning that the guests are gas molecules encased in a host framework of water molecules. Gas hydrates only form and remain stable in specific temperature and pressure regimes that depend on the nature of the guest molecules [3]. Theoretical phase diagram of clathrate hydrates show that it would be possible to form clathrates at very low pressure (10&lt;sup&gt;-10&lt;/sup&gt; bar) and temperature (&lt; 80 K), but there is a critical lack of experimental data using these preparation methods [4]. Could clathrate hydrates be formed under conditions relevant to the interior of comet nuclei?&amp;#160; The formation and characterization of these ice-like structures under such conditions could provide valuable experimental evidence for understanding the preservation of some volatile species during the thermally-induced evolution of comets.&amp;#160;&lt;/p&gt; &lt;p&gt;In an effort to assess whether hydrates may play a role in maintaining volatile species in cometary material, FTIR spectroscopic identification of several species have been performed. We present results related to carbon dioxide and methane hydrates, in conditions relevant to cometary nuclei, i.e. at low temperature (10 K) and pressure (base pressure 10&lt;sup&gt;-7&lt;/sup&gt; mbar) regimes. To understand the nature of the gas hydrates formed under these conditions, vibrational spectra of distinct gas/ice interactions (clathrate hydrate, gas in/on water ice) were compared. The behaviour of the water crystalline skeleton interactions with the trapped molecules at different temperatures, as well as the influence of the gas mixture and the deposition method, will be presented.&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;&lt;/p&gt; &lt;p&gt;This study is part of a project that has received funding from the European Research Council (ERC) under the European Union&amp;#8217;s Horizon 2020 research and innovation programme (Grant agreement No. 802699).&lt;span class=&quot;Apple-converted-space&quot;&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;[1] Prialnik et al. (2004) in Comets II, Festou, Keller and Weaver (Eds.), 359-387&lt;/p&gt; &lt;p&gt;[2] Mandt et al. (2017) in Comets as Tracers of Solar System Formation and Evolution, Mandt, Mousis, Bockel{\'e}e-Morvan and Russel (Eds.)&lt;/p&gt; &lt;p&gt;[3] Sloan (2003) Nature, 426, 353-359&lt;/p&gt; &lt;p&gt;[4] Choukroun et al. (2003) in The Science of Solar System Ices, Gudipati and Castillo-Roguez (Eds.), 409-454&amp;#160;&lt;/p&gt;

The next step for Rosetta ROSINA/DMFS data of comet 67P/Churyumov-Gerasimenko: the search for semi-volatiles species.

&lt;p&gt;Using data from Rosetta/ROSINA&amp;#8217;s Double Focusing Mass Spectrometer (DFMS), a zoo of neutral molecules have been discovered in the coma of 67P/Churyumov-Gerasimenko, which led to a wealth of new insights regarding the comet itself, its formation and the early history of our Solar System.&lt;/p&gt; &lt;p&gt;A comprehensive understanding of the overall comet composition requires information on all species involved i.e. the volatiles, semi-volatiles and refractories in the coma. However, while ROSINA targets volatiles and GIADA, MIDAS and COSIMA studied refractories, no instrument on Rosetta provides measurements specifically of semi-volatiles. In some circumstances, ROSINA/DFMS may provide at least some information on semi-volatiles in the coma. As semi-volatile species are progressively released from the grains into the gas coma (their release depends on cometocentric distance and grain size), they can be identified if the abundance ratio of a candidate semi-volatile species (or a fragment thereof) to a volatile species increases as a function of distance from the nucleus. This constitutes a so-called distributed source in the coma.&lt;/p&gt; &lt;p&gt;With a mass spectrometer like DFMS, one does not detect neutral coma species, but rather the ionized products thereof after electron impact ionization. A major difficulty is assigning the observed ions to parent neutrals. As semi-volatile species have a low abundance, sum spectra obtained through accumulation of individual DFMS spectra can improve the signal-to-noise ratio in order to provide decisive information for identification. Accurate sum spectra can only be obtained provided all instrument-dependent effects are accounted for.&lt;/p&gt; &lt;p&gt;This contribution focuses on the procedure used to create sum spectra and presents some typical results.&lt;/p&gt;