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Friday Earth Sciences Talk

Dr Tjalling de Haas: 'Formative mechanisms of recent mass flows on Mars. Have we been fooled by equifinality?'

Martian gullies are kilometer-scale landforms consisting of an alcove, channel and depositional fan. They are among the youngest landforms that may have formed by liquid water and are active today. Understanding their formation is thus critical for resolving Mars’s most recent climatic history and potential to sustain life. Gullies have been hypothesized to have been formed by either the action of liquid water and brines or the action of sublimating CO₂ ice, but the jury is still out. Martian gullies strongly resemble terrestrial systems formed by aqueous debris flows, having similar sedimentology, morphology, and morphometry. Yet, new deposits have formed within multiple gullies across Mars, and we cannot reconcile these flows with the low availability of atmospheric water and the triple point of water under present Martian conditions, while CO₂-ice is observed to have been present during these recent flows. But can CO₂ sublimation really support mass flow on Mars? During this talk I will present the pros and cons of both potential mechanisms, and give a sneak preview of recent revolutionary mass-flow experiments in low-pressure tanks mimicking the martian atmosphere. These experiments finally break the long-lasting stalemate on the formative processes of Martian gullies!

With the Friday Earth Sciences Talks (FEST) we intend to bring the departments of Earth Sciences and Physical Geography together. The aim is to present (mostly) Utrecht-based Earth Sciences in an accessible way in order to stay familiar with each other’s work across disciplines. Alumni and students are also invited, in particular MSc students in Earth Sciences. Free access, no registration required.