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Feuillet N.,CNRS Paris Institute of Global Physics
Geophysical Research Letters | Year: 2013

At Santorini, active normal faulting controls the emission of volcanic products. Such geometry has implication on seismic activity around the plumbing system during unrest. Static Coulomb stress changes induced by the 2011-2012 inflation within a preexisting NW-SE extensional regional stress field, compatible with fault geometry, increased by more than 0.5 MPa in an ellipsoid-shaped zone beneath the Minoan caldera where almost all earthquakes (96%) have occurred since beginning of unrest. Magmatic processes perturb the regional stress in the caldera where strike-slip rather than normal faulting along NE-SW striking planes are expected. The inflation may have also promoted more distant moderate earthquakes on neighboring faults as the M > 5 January 2012, south of Christiania. Santorini belongs to a set of en echelon NE-SW striking rifts (Milos, Nysiros) oblique to the Aegean arc that may have initiated in the Quaternary due to propagation of the North Anatolian fault into the Southern Aegean Sea. Key Points Active faulting at Santorini rift and link with volcanoes The 2011-2012 inflation has increased the stress on rift bounding faults The seismicity pattern in the Caldera is well explained by the stress increase © 2013. American Geophysical Union. All Rights Reserved. Source


Badro J.,CNRS Paris Institute of Global Physics | Badro J.,Ecole Polytechnique Federale de Lausanne
Annual Review of Earth and Planetary Sciences | Year: 2014

Mantle minerals at shallow depths contain iron in the high-spin electronic state. The crystal-field splitting energy increases with increasing pressure, which can favor the low-spin state. Hence, pressure-driven transitions from the high-spin to the low-spin state were proposed as early as the 1960s, and minerals in the lower mantle were suggested to contain iron in the low-spin state. Only in the past 10 years did experiments and calculations prove that iron in mantle minerals transforms from high-spin to low-spin at lower-mantle pressures. This transition has important consequences for volume, thermodynamics, and bonding. In a geophysical framework, the transition would affect the dynamics and thermochemical state of the lower mantle, through combined effects on density, elasticity, element partitioning, and transport properties. These observations provide the basis for a new paradigm of the physics and chemistry in Earth's lower(most) mantle. © 2014 by Annual Reviews. All rights reserved. Source


Grant
Agency: Cordis | Branch: H2020 | Program: ERC-STG | Phase: ERC-StG-2014 | Award Amount: 1.49M | Year: 2015

The objectives of this proposal, PRISTINE (high PRecision ISotopic measurements of heavy elements in extra-Terrestrial materials: origIN and age of the solar system volatile Element depletion), are to develop new cutting edge high precision isotopic measurements to understand the origin of the Earth, Moon and solar system volatile elements and link their relative depletion in the different planets to their formation mechanism. In addition, the understanding of the origin of the volatile elements will have direct consequences for the understanding of the origin of the Earths water. To that end, we will approach the problem from two angles: 1) Develop and use novel stable isotope systems for volatile elements (e.g. Zn, Ga, Cu, and Rb) in terrestrial, lunar and meteoritic materials to constrain the origin of solar systems volatile element depletion 2) Determine the age of the volatile element depletion by using a novel and original approach: calculate the original Rb/Sr ratio of the Solar Nebula by measuring the isotopic composition of the Sun with respect to Sr via the isotopic composition of solar wind implanted in lunar soil grains. The stable isotope composition (goal #1) will give us new constraints on the mechanisms (e.g. evaporation following a giant impact or incomplete condensation) that have shaped the abundances of the volatile elements in terrestrial planets, while the timing (goal #2) will be used to differentiate between nebular events (early) from planetary events (late). These new results will have major implications on our understanding of the origin of the Earth and of the Moon, and they will be used to test the giant impact hypothesis of the Moon and the origin of the Earths water.


Grant
Agency: Cordis | Branch: H2020 | Program: MSCA-IF-EF-CAR | Phase: MSCA-IF-2015-EF | Award Amount: 185.08K | Year: 2016

The stable isotope geochemistry of chlorine (Cl) and bromine (Br) are considerably different. While most Cl isotope data are in the range from -1.21 to \0.40, Br isotope data are from -0.06 to \1.48. Interesting is that Br isotope variations are of the same magnitude as Cl isotope variations. Also Br isotope values of ancient evaporites are very positive (\0.6), impossible to explain from oceans with a modern isotope composition. These data are unexpected considering the small fractionation factors for Br compared to Cl. The research we propose aims at understanding these observations and developing halogen stable isotopes to study fluid transport processes in porous media. This research has a great potential to understand the history and the migration of fluids in deep porous reservoirs which are considered for geological storage of CO2, H2 and hydrocarbons. First we aim to study historical variations of Br isotope compositions in the earths surface reservoirs. We will study Br isotope variations in ancient evaporites that reflect Br isotope ratios of the oceans at the moment they were deposited. Second to study the geochemical processes that affect Cl and Br isotope variations. Isotope fractionation during ion-filtration that has never been studied in detail. This process is important to understand subsurface fluid flow and fractionation of ions and isotopes during fluid transport. We aim at studying Cl and Br isotope variations during this process. Also redox processes have hardly been studied. Oxidation processes can increase Br isotopes values more than Cl in spite of Brs much smaller isotope fractionation factors. Third to understand our observations we will compare the data obtained during this study with the geochemical cycles of Cl and Br. This will allow us to develop future research to continue to improve our knowledge on Cl and Br isotope variations as proxies to understand chemical cycles on earth, especially in fluids in deep porous reservoirs.


Grant
Agency: Cordis | Branch: H2020 | Program: MSCA-IF-EF-ST | Phase: MSCA-IF-2015-EF | Award Amount: 173.08K | Year: 2016

Arsenic is a notorious toxin, and as such may have exerted a strong selective pressure on the distribution and evolution of life on Earth. Despite evidence supporting the high levels and prominent role of As on the primitive Earth, the essentiality and toxicity of As, and its impact on evolutionary processes remains unexplored. AsLife aims at taking a novel approach to assessing microbial As cycling by exploiting two linked environments. The first are the microbial mats from High-Altitude Andean Lakes, where it is known that As concentrations are far above background levels. Specifically, living and diagenetically-modified microbial mats will be investigated using scanning hard X-ray nanoprobes emerging at synchrotron facilities. This non-invasive and non-destructive technique provides data on a sub-micrometer scale by which to tie physiological inference from trace metal(loid)s distribution and speciation patterns directly to the microfossil biomass. Thus, providing a means to understand the interplay between microbial metabolisms and bio-availability of trace metal(loid)s in living and fossil ecosystems. The second environment comprises laboratory cultures, using the sampling power of adaptive laboratory evolution to explore how microbes adapt and enhance As detoxification facing the extreme As levels present in Andean Lakes. These results will be discussed in light of genomic studies of As-rich microbiota performed by Argentinian colleagues. During this project I will contact colleagues of the Jet Propulsion Laboratory in charge of the 2020 Mars Science Rover Mission and linked objective of returning samples for future analysis on Earth. I believe that my expertise in imaging and analyzing bio-geochemical proxies at multiple scales on a encapsulated geological sample can be relevant for contributing to the Seek Signs of Life Exploration Strategy of the 2020 Mission, thus establishing a strong and effective collaboration between EU and USA.

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