GeoHyd Lunch Seminar: Constraining frost weathering potential, formation history and subsurface processes of blockfields in Norway and Svalbard
Welcome to our GeoHyd Lunch Seminar on Friday 14th of June @ 12:15 in Aud. 1 in the Geology Building, or via videolink using Zoom. The seminar is held by Maria Peter (Norwegian University of Science and Technology).
Seminar by Maria Peter (Norwegian University of Science and Technology)
Constraining frost weathering potential, formation history and subsurface processes of blockfields in Norway and Svalbard
Abstract:
Blockfields are landforms that cover the ground surface at high elevation-low relief surfaces in many cold mountain regions and formerly glaciated areas. They are composed of a surface layer of coarse-grained, often angular to subangular cobbles and boulders and air-filled voids and a sandy-silty matrix-supported layer below with fewer blocks. The formation history and paleo glaciological implications have been and are still a subject of debate. The most likely explanation is that these landforms outline formerly cold-based areas below the ice sheets of the most recent glaciations and thus could indicate very old surfaces with very low erosion and weathering rates. I investigated the frost weathering potential in three different blockfield sites on the Norwegian mainland and Svalbard, using numerical modeling and measured temperatures in different morphological settings and climates. Additionally I present an approach to constrain age, erosion and possible subsurface fluctuations at these surfaces using cosmogenic nuclide dating and connected MCMC modeling of two depth profiles in one of the blockfield sites.
The modeling of frost weathering potential shows a high sensitivity to different stratigraphies: coarse-grained surface layers with air-filled voids produce the lowest frost weathering potentials while the more fine-grained (sand, silt, gravel) sediment fills up those voids, the higher the frost weathering potential. Likewise, a dry and cold climate with cold winters and continuous snow cover, produces low frost weathering potential, while warmer winters with frequent temperature fluctuations and rain/melt events produce the highest frost weathering potential. Permafrost limits frost weathering as both the water availability is limited in winter and air and ground surface temperatures are too cold after the initial freeze-up in fall. The cosmogenic nuclide dating and inverse modeling reveal oldest ages for the fine-grained sediment and youngest for the cobbles and boulders from the depth profiles, which points to mixing mechanisms and frost heave. Erosion rates for the sediment have been calculated to be < 5 m/Ma, during the last 600 ka.
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The GeoHyd seminars are normally held in Auditorium 1 in the Geology Building, Blindern (map) but it is also possible to follow the seminars at Zoom.
Videolink to the lectures will be sent to the e-mail list alle@geo and geohyd-info@geo. If you want to subscribe to the geohyd-info@geo mailing list send an email to Anita.
About the seminar series
The talks in GeoHyd Lunch Seminar Series are offered by the Section for Geography and Hydrology (GeoHyd), Dept. of Geosciences, University of Oslo. The seminars are announced as lunch seminars so bring your lunch if you want to.
The seminars are open for everyone interested, and especially students are welcome.
The Lunch Seminar Team
– Thomas and Yeliz
Published June 10, 2024 9:52 AM
- Last modified June 10, 2024 9:52 AM