PhD position: Study of radiative properties of dry and crystal rich magmas
The “Magma” group of the ISTO (Earth Science institute of Orléans ISTO- CNRS, Orleans; University of Orleans France; www.isto-orlea
We offer 3 years PhD studentship starting 1st October 2018 financed by the French Research and Education Ministry/Centre department. This PhD proposal is also related and supported by the French Equipex project PLANEX (Experimental Planet: high pressure – high temperature platform for in situ analyses and simulations; https://www.univ-
The closing date for application is 6th April 2018.
Project description:
To predict and to minimize the impact of volcanic eruptions, it is necessary to determine the temperature of the magma at surface level, since together with the crystal content and the composition of the melt, the temperature plays a main role in controlling the rheological properties of the magma (viscosity) and the volcano final behavior (i.e., explosive vs effusive). For a better understanding of volcanic and magmatic systems, as well as other geological processes involving temperature (i.e., Earth inner heat flux from the core towards the crust), it is crucial to determine the parameters and processes that control thermal properties of magmas. The absolute magmatic temperature can be determined with either direct (Infrared measurements) or indirect methods (mineral geothermometers, thermodynamic models, phase equilibria experiments). Direct techniques currently use infrared thermal cameras that determine the surface temperature via the thermal radiation (E, emissivity) of the magmatic body. Such measurements are commonly performed from distances varying from tenth to hundred meters from the thermal focus, to up to several kilometers in airborne or satellite-based cameras. However, some factors related to the atmospheric conditions (humidity, density and air temperature), to the presence of other radiative source (i.e., sun) as well as to changes in the physical properties of the flow (cooling, crystallization and related magma viscosity increase) can strongly affect the body radiation and thus impact the final magma temperature. Consequently, in order to determine an accurate magmatic body’s temperature, to calibrate IR temperature measuring devices and to minimize parasite environmental effects on Infrared thermal measurements, it is of paramount importance to compare/refine IR field data with measurements obtained in laboratory.
Project main goals:
This project has an important innovative character since to date, there are not similar measurements performed at relevant magmatic conditions. The main objective of this project resides in the study of the radiative properties of dry and crystal rich magmas (up to 60wt%) performed at real magma temperature conditions (up to 1200ºC). First, the candidate will measure the thermal emissivity of different natural samples (from basalts to rhyolites) with compositions representative of actual volcanic arcs. This study will allow exploring the effect of composition on the radiative properties of magmas. Secondly, similar studies will be performed on experimental samples having different crystal contents and synthesized at ISTO laboratory using conventional Internally Heated Pressure vessels, at high pressure and high temperature by the candidate. The goal of the second part is to determine the effect of crystal load (amount and type of crystals) on the radiative properties since the presence of minerals can significantly modify the physical properties of magmas (viscosity) and phonon transport. Another innovative objective of this work is the comprehension of the effect of the cooling-rate of a magmatic body on thermal properties, with the aim of simulating the process of crust formation in active lava flows. The obtained results will be compared to the field data and incorporated to existing numerical lava flow models in order to refine and improve the interpretation of flowing magmatic bodies. Infrared Emissivity measurements as function of high temperature will be performed at CEMHTI whereas the petrographic characterization of natural and experimental products will be done at ISTO using various technical facilities (SEM, EMPA, FTIR, Raman). We expect that the candidate will establish a new Infrared Emissivity database of dry and crystal rich magma compositions representative of the terrestrial magmatism. These data are crucial in the determination, interpretation/modeling of the thermal exchange of magmas at low-pressure environments and the surface. In addition, the new database will help in improving the exploration of extraterrestrial planets since this research is mostly based on IR data obtained from satellites and telescopes.
PhD requirements:
We are looking for a candidate with the following skills:
- Master’s degree in geology /petrology with strong background in vibrational spectroscopy or
Master’s degree in physics-chemistry of materials/vibrational spectroscopy with strong background in geology/petrology.
- Strong experimental abilities to perform laboratory/field measurements.
- Scientific curiosity, enthusiasm, motivation, open-minded, autonomy, capacity to work in pluridisciplinary team, sense of organization.
- High level of spoken and written English.
- Spoken/written French will be appreciated.
- Previous experiences in thermal Infrared measurements on active volcanic systems will be highly valorised.
Interested candidates are required to send the following documents by e-mail to both PhD directors and before 6th April 2018:
ð Detailed CV, motivation letter and contact details of 2 referees.
Dr Joan Andújar: juan.andujar@cnrs
Volcano Listserv is a collaborative venture among Arizona State University (ASU), Portland State University (PSU), the Global Volcanism Program (GVP) of the Smithsonian Institution's National Museum of Natural History, and the International Association for Volcanology and Chemistry of the Earth's Interior (IAVCEI).
ASU - http://www.asu.edu/ PSU - http://pdx.edu/ GVP - http://www.volcano.si.edu/ IAVCEI - http://www.iavcei.org/
To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxx.
To contribute to the volcano list, send your message to: volcano@xxxxxxx. Please do not send attachments.
==============================================================
