Petrologic and geochemical constraints on volcanic eruptions on Amazonian Mars

Nakhla meteorite against a white background

The Nakhla meteorite 

Nakhlites are a unique suite of  around 20 Martian meteorites. They are basaltic pyroxenites with mineralogies dominated by cumulative pyroxene and olivine.

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 [e.g. 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.

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.

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.

Eligibility

To be classed as a home student, candidates must meet the following criteria:

  • Be a UK National (meeting residency requirements), or
  • Have settled status, or
  • Have pre-settled status (meeting residency requirements), or  
  • Have indefinite leave to remain or enter  

 If a candidate does not meet the criteria above, they would be classed as an International student.

Further guidance on UKRI Eligibility Criteria can be found on the UKRI website

How to apply

Please send the following documents to Anna Hutson (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.

Apply for this project

This is an Science and Technology Facilities Council (STFC) funded studentship.

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

Application deadline: 29 January 2021

Any questions?

Natural History Museum

Paul Schofield

We welcome applications from everyone

We offer a stimulating and professional environment in which to work. We look for staff who can work according to our values: diversity, creativity, connection and evidence-based thinking. 

Supervisors

Natural History Museum

Paul Schofield

Chiara Petrone 

University of Plymouth

Natasha Stephen

University of Oslo

Agata Krzesińska 

References

[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), doi: 10.1038/ncomms12946

Relevant issues of Elements Magazine:

Mineralogy of Mars (2015) Volume 11 (1)

Water on Mars (2006) Volume 2 (3)

Volcanoes (2017) Volume 13 (1)