PICS Seminar: Mathieu Lapotre (Harvard)

Mathieu Lapotre (Harvard)
Tuesday, February 27, 2018 - 12:30pm to 1:30pm

Paleoenvironmental Constraints from Quantitative Sedimentology and Geomorphology: Canyon Erosion and Sand-Ripple Formation on Mars

The geologic records of terrestrial planets in our Solar System attest to the volatility of habitability. The history of Mars, in particular, is one of dramatic change that transformed a hospitable environment into the barren land we know today. Deciphering Mars geologic past using data from orbiting and landed spacecraft requires using and adapting theory and techniques that were developed for Earth. In return, Mars oers a unique test for Earth-based theory under alien boundary conditions. In this presentation, I demonstrate how a mechanistic understanding of surface processes sheds light onto Martian paleohydrology and paleoclimate through two examples: the erosion of bedrock canyons by water, and the formation of sand ripples by winds. I rst question the classic assumption that Martian bedrock canyons formed from groundwater-seepage erosion, and show that surface water flows carved those canyons instead. Second, I present a unifying theory for sand-ripple formation across uids that can explain the ubiquity of anomalously large eolian ripples on modern Mars and help constrain atmospheric conditions on ancient Mars. Our results have surprising implications for our understanding of terrestrial landscapes and Mars potential as a refugium for early life in the Solar System.

About the Speaker:

Mathieu Lapotre is the John Harvard Distinguished Science Fellow in the Department of Earth and Planetary Sciences At Harvard University. His research "aims at unraveling the physics of sedimentary processes that shape the surfaces of terrestrial planets, including Earth, and ultimately, what their landforms and rocks tell us about past hydrology, climate, and habitability." Although he has broad interests across planetary bodies of our solar system and beyond, his work on planetary surface processes largely focuses on Earth and Mars. Three main goals of his research are to: (1) Further our mechanistic understanding of sedimentary and erosional processes on Earth, (2) explore how planetary conditions affect surface processes and their record in sedimentary rocks, and (3) constrain the paleohydrology, paleoclimate, and habitability of planets from physics-based interpretations of their sedimentary records.

About the Series

The MIT Planetary Lunch Colloquium Series [PlCS] is a weekly seminar series organized within the EAPS department. Colloquia topics span the range of research interests of the department's planetary sciences research program. The seminars usually take place on Tuesdays from 12-1:30 pm in 54-517 unless otherwise noted (term-time only). Speakers include members of the MIT community and visitors. Talks are intended to appeal to graduate students, postdocs, research scientists, and faculty with a background in planetary science. A light lunch is provided.