Disputas og prøveforelesning er i Auditorium 1 i Geologibygningen. I noen tilfeller vil prøveforelesning og disputas være mulig å delta på digitalt, i så fall blir det lagt ut en lenke til Zoom.
Delta via Zoom (webinar)
Prøveforelesning
Fredag 4 april, 10:15-11:00, Aud 1, Geologibygningen:
Jelly Sandwich or Crème Brûlée revisited- the Rheology of the Lower Crust and implications for geodynamics
Kreeringssammendrag
I denne doktorgradsavhandlingen undersøkes de kjemomekaniske prosessene som skjer ved et enkelt brudd og dannelsen av en pseudotachylytt (avkjølt seismogen-avledet friksjonssmelte) ved nærvær og fravær av infiltrasjon av væske. Michalchuks avhandling viser sammenhengen mellom metamorfose, væske-bergart interaksjoner og reologiske transformasjoner i den nedre jordskorpen ved jordskjelv.
Hovedfunn
Populærvitenskapelig artikkel om Michalchuks avhandling:
Fracturing, fluid-rock interactions, and metamorphism in lower-crustal pseudotachylyte-bearing faults
Earthquakes in the dry and strong lower crust can introduce and mobilize fluids along fracture networks that may kickstart metamorphic reactions and promote long-term rheological transformations. Fluid-rock interactions are important because fluids facilitate element transport, they increase metamorphic reactions rates, and they promote viscous deformation. The doctoral thesis from Stephen Paul Michalchuk explores the chemo-mechanical processes operating as a result of single rupture earthquakes and the formation of a pseudotachylyte (solidified earthquake-derived frictional melt), in the presence and absence of fluid infiltration, using a plethora of micro-analytical techniques.
Michalchuk’s analyses have found that earthquake-induced metamorphic transformations are exceedingly fast (minutes-hours) in entirely dry systems. The damage zone flanking a pseudotachylyte is efficiently healed following an earthquake, and that multiple fracturing events are required to mobilize the minute amount of fluids available in dry rocks towards the grain boundaries. The post-seismic growth of garnet is a densification process that results in porosity forming at the grain boundaries around garnet. Fluids at the grain boundaries and fluids filling porosity facilitate viscous deformation that eventually transforms the pseudotachylyte and the adjacent damage zones into a ductile shear zone. The findings in the doctoral thesis demonstrate the interconnected relationship between metamorphism, fluid-rock interactions, and rheological transformations of the lower crust.
Foto og annen informasjon:
Pressefoto: Stephen Paul Michalchuk, portrett; 1000px. Foto: Privat
Annet bildemateriale: Figur med beskrivelse og kreditering som spesifisert i artikkelen over, størrelse 1280px.