APEX returns! Mantle layering, long-term evolution and surface tectonics on rocky planets

Our Astrobiology and Planetary Exploration (APEX) seminar series resumes in term 2, this Friday 30th January at 13:00 GMT, featuring the following talk:

•  Maxim Ballmer (UCL): Mantle Layering, Long-term Evolution and Surface Tectonics on Rocky Planets

An abstract for Maxim’s talk can be found below.

Please note that APEX continues at Fridays at lunchtimes this term from 1-2 pm GMT, in Birkbeck room MAL 612, 6th floor of the Birkbeck main Malet Street building, and online (unless specified ‘online only’ below).

A hybrid (in-person and online) format will continue this term but, of course, we warmly encourage in-person attendance to support our visiting speakers.

Details of the forthcoming APEX programme can be found at the link below. The latest information will be advertised in advance of each meeting.  If you are not on our regular mailing lists and are interested in attending these seminars, please contact joanna.fabbri AT ucl.ac.uk.

Talk abstract

The tectonic style and mantle structure of rocky planets controls their thermal evolution, secondary atmosphere and thus habitability. Here, we present the results of two geodynamic studies that address the co-evolution of the mantle and lithosphere/crust, shaping surface deformation, magmatism and long-term evolution.
The first study addresses the style of crystallization of the magma ocean (MO), the initial hot stage of a rocky planet that sets up the starting conditions for core-mantle-lithosphere evolution. We find that melting in the solid mantle during the last stages on MO crystallization regulates the composition of the first solid crust on a rocky planet, and thus after a global-scale overturn, that of a basal silicate layer (BSL). Our findings can address the Mars-Earth dichotomy of lowermost-mantle structure, with a BSL present on Mars, but absent on Earth. They also predict a systematic trend of BSL preservation with planet size.

The second study addresses the long-term tectonic evolution of Earth-like planets. Using 2D geodynamic models, we predict that Earth-like planets can assume variable tectonic regimes as a function of mantle thermal state (corresponding to age) and lithospheric strength.  We map out these tectonic regimes (mobile lid; stagnant lid; plutonic-squishy lid; sluggish lid; and two episodic lid modes that alternate between different regimes over time) to constrain the tectonic evolution of Earth and Venus. While, for instance, mobile-lid (e.g., plate-tectonic) surface dynamics promotes mountain building and thus silicate weathering as well as planetary ingassing at subduction zones, stagnant-lid planets exhibit inefficient erosion/weathering (i.e., old surfaces) and dominant outgassing. This work also has implications for our understanding of the Archean geologic record, and Venusian surface topography.

Links 

• Maxim Ballmer’s academic profile
• APEX programme for this term
• Recordings of previous APEX talks

APEX Seminars

The Astrobiology and Planetary Exploration (APEX) seminar series takes place this term on Friday lunchtimes, from 1-2pm, in Birkbeck room MAL 612, on the 6th floor of the Birkbeck main Malet Street building, and online.  As in previous years, we will operate a hybrid (online and in-person) model for both speakers and attendees. Details of the forthcoming APEX programme can be found via the link below.

• Link to further information about our APEX seminars

Some of our past APEX talks can also be viewed online.