Petrologic and geochemical constraints on volcanic eruptions on Amazonian Mars

A fragment of the Nakhla meteorite

A fragment of the Nakhla meteorite

This PhD project is a multi-disciplinary study in which the student will analyse the chemistry and petrography of nakhlite meteorites.

This studentship is funded by the Science and Technology Facilities Council (STFC) and starts October 2020.

Apply for this project

Read the eligibility criteria and application guidance below, then send your application to postgradoffice@nhm.ac.uk

Application deadline: Friday 28 February 2020.

Overview

Nakhlites are a unique suite of ~20 Martian meteorites. They are basaltic pyroxenites with mineralogies dominated by cumulative pyroxene and olivine. Traditionally considered to represent a shallow igneous sill, recent models suggest that the nakhlite meteorites sample several different lava flows, all from the Amazonian period about 1.3 Ga.

Additionally, nakhlites are known to have the best evidence for fluid alteration within the Martian surface/subsurface, hosting a range of secondary phase assemblages. Alteration minerals include Fe,Mg-phyllosilicates (clay minerals), carbonates, sulphates and halides all of which likely formed during brief aqueous subsurface events.

The nature and origin of these secondary minerals has been studied with a view to constrain the fluid geochemistry and the habitability of the Martian subsurface.

Systematic petrography and geochemistry have grouped the nakhlite meteorites into distinct lava flows from up to four eruption events. However, many inconsistencies remain regarding geochemical characterization of separate flows and their petrofabric characteristics [eg 1,2].

Furthermore, discrete oxidation processes during eruption are recorded in some of the nakhlites with some features suggestive of magma contamination. Therefore, the evolution of magma in the nakhlite magma chamber is expected to be complex and is still subject to debate.

Indeed, whether nakhlites originated from the same parental melt or from multiple magmatic systems has yet to be clarified. By investigating crystallization dynamics and relative timescales for the nakhlites, temporal constraints may be developed for the nakhlite magmatic system.

Project aims and methods

This project is a multi-disciplinary study in which the student will analyse the chemistry and petrography of nakhlite meteorites.

We will use petrographic techniques to identify specific chemical textures within the pyroxenes and olivines. Quantitative and greyscale imaging from electron microscopy will be used to develop systematic diffusional models [3,4]. This will establish pre-eruptive processes, and lava emplacement histories.

In addition to utilising instrumentation within the Image and Analysis Centre (Natural History Museum) and at Plymouth Electron Microscopy Centre (University of Plymouth), there is scope to perform micro- and nano-scale microscopy at international research facilities such as Diamond Light Source.

This project is particularly timely with respect to the ongoing space missions by the North American and European space agencies (NASA and ESA).

NASA’s Curiosity Rover, Mars Reconnaisance Orbiter and Insight missions, and ESA’s Trace Gas Orbiter are all currently operational with the ESA Rosalind Franklin Rover (part of the ExoMars programme) and Mars 2020 (NASA program) due to land on the Martian surface in 2021.

Graphs and images from a research paper analysing terrestrial volcanic rocks

High resolution BSE (back-scattered electron) maps, acquired using a state-of-the-art electron microprobe on terrestrial volcanic rocks, of chemical zonation in pyroxene crystals. This project will apply greyscale image processing techniques on such elemental zoning textures within the nakhlites. In so doing it will be possible to establish the systematics of timescales and dynamics of magma storage in these samples.

This example is from reference [4].

Training and supervision

The student will become integrated into the Planetary Materials Group at the Natural History Museum and the Centre for Research in Earth Sciences (CRES) at the University of Plymouth, and have the opportunity to study meteorites from one of the finest meteorite collections in the world at the Natural History Museum.

The student will benefit from STFC-led training opportunities throughout the studentship, and also from an award-winning researcher development programme at the University of Plymouth.

Scanning electron microscopy (SEM) & electron microprobe analysis (EMPA) will be performed in house, at both the Museum’s Image and Analysis Laboratories and the University of Plymouth’s Electron Microscopy Centre (PEMC) alongside the School of Geography, Earth & Environmental Science’s research facilities.

If required, additional micro- and nano-scale X-ray and infrared microscopy will be undertaken at international synchrotron facilities such as the UK’s Diamond Light Source, using X-ray nanoprobes and  scanning transmission X-ray microscopy (STXM).

We seek an enthusiastic person for this project with a strong background in the physical sciences or planetary sciences or geology, and with an interest in applying analytical mineralogy to a planetary science context.

Eligibility

Projects are funded for 3.5 years as an STFC studentship, which will cover all fees and a student stipend if you are from the UK, or from the EU and meet residency requirements (settled status, or 3 years full-time residency in the UK). For full details on what is covered by the studentship please see the STFC guidance.

For informal enquiries or further information, please contact Dr Paul Schofield or Dr Natasha Stephen.

How to apply

Deadline: Friday 28 February 2020

Please send the following documents to Anna Hutson at postgradoffice@nhm.ac.uk

  • Curriculum vitae
  • Covering letter outlining your interest in the PhD project, relevant skills training, experience and qualifications, and a statement of how this PhD project fits your career development plans.
  • Transcripts of undergraduate and Masters’ degree results.
  • Two academic references including (if applicable) Masters’ project supervisor.

Interview date: March 2020

Start date:          October 2020

Further Information

For informal enquiries or further information, please email

Main supervisor: Dr Paul Schofield

Supervisors

The Natural History Museum
University of Plymouth
University of Oslo

References and suggested reading

  1. Udry A., Day J.M.D. (2018) 1.34 billion-year-old magmatism on Mars evaluated from the co-genetic nakhlite and chassignite meteorites. Geochimica et Cosmochimica Acta 238, 292-315.
  2. Daly L. et al. (2019) Understanding the emplacement of Martian volcanic rocks using petrofabrics of the nakhlite meteorites. Earth and Planetary Science Letters 520, 220-230.
  3. Petrone C.M., Braschi E., Francalanci L., Casalini M., Tommasini S. (2018) Rapid mixing and short storage timescale in the magma dynamics of a steady-state volcano. Earth and Planetary Science Letters 492, 206-221.
  4. Petrone C.M., Bugatti G, Braschi E., Tommasini S. (2016) Pre-eruptive magmatic processes re-timed using a non-isothermal approach to magma chamber dynamics. Nature Communications 7 (1), 12946.
Relevant issues of Elements Magazine

Funded by 

Submit your application