Evidence of glacier-permafrost interactions associated with hydro-geomorphological processes and landforms at Snøhetta, Dovrefjell, Norway

Glacier-permafrost interactions are investigated to understand glacial-hydrological influence along a partly glacierised valley on the NE flank of the Snøhetta massif, Dovrefjell, southern Norway. Of particular interest is how processes are controlled by a hydrological connection between landforms. Field mapping identified an ice-marginal landsystem comprising a polythermal glacier, a proglacial lake, an ice-cored moraine complex and a river-lake with perennial frost mounds. A clear interaction between glacial and periglacial processes was observed in transitional landforms, most prominently in the ice-cored moraine which constitutes a permafrost environment that is directly reworked by glaciofluvial processes. The role of this interaction in controlling seasonal, partial drainage of the proglacial lake was assessed using remote sensing-based observations of lake surface size evolution and seasonal surface subsidence. Results suggest a two-fold threshold for lake drainage: Depending on the dynamics of glacial discharge and active layer depth, the ice-cored moraine may either act as a barrier or a pathway to meltwater exiting the glacier. This demonstrates the importance of meltwater dynamics in controlling landform evolution in a glacial-periglacial landscape. To further assess the importance of surface and subsurface hydrology in linking glacial and periglacial domains, water stable oxygen isotope ratios across the study area were studied to map the flow of meltwater from glacier to permafrost. Results include a model of the surface and subsurface hydrology in the catchment and promote a conceptual understanding of water as a thermal, hydraulic and mechanical agent of transient glacier-permafrost interaction operating at heterogeneous timescales.publishedVersio

Morfología polínica de Cactáceas en el norte de Chile

Chile is habitat to over 140 species of cactus of which 45% are endemic and most of them grow in the arid northernmost partof the country between 18°-32°S. As the Cactaceae family plants are quite well adapted to arid environments, their fossilpollen may serve as a tool to reconstruct past environmental dynamics as well as to trace some issues regarding the familyevolution or even some autoecological aspects. Aiming to create a reference atlas to be applied to some of these purposes,the pollen morphology of the following 14 different species of the Cactaceae family from Northern Chile was studiedunder optical microscopy: Cumulopuntia sphaerica, Maihueniopsis camachoi, Tunilla soehrensii, Echinopsis atacamensis,Echinopsis coquimbana, Haageocereus chilensis, Oreocereus hempelianus, Oreocereus leucotrichus, Copiapoacoquimbana, Eriosyce aurata, Eriosyce subgibbosa, Eulychnia breviflora, Browningia candelaris and Corryocactusbrevistylus. Pollen grains of species of the subfamily Opuntioideae are spheroidal, apolar and periporate whereas grains ofthe subfamily Cactoideae are subspheroidal, bipolar and tricolpate and can be taxonomically differentiated between tribes.The results show that it is possible to identify pollen from the Cactaceae family at the genus level but pollen taxonomicresolution may be complicated to identify up to a specific level. A wider reference collection considering more charactersthan those included in the present study could improve this aspect in the near future.Actualmente crecen en Chile más de 140 especies de cactus, de las cuales el 45% son endémicas y la mayoría de ellas sedistribuyen en la zona norte y más árida del país entre 18°-32°S. Como las Cactáceas se encuentran muy bien adaptadas a losambientes áridos, el polen fósil de esta familia puede ser utilizado como herramienta para reconstruir la dinámica ambientalpasada así como para estudiar aspectos relacionados a su historia evolutiva o bien de su autoecología. Con el objetivo decrear una colección de referencia asociada a los propósitos mencionados anteriormente, se estudió con microscopía óptica lamorfología del polen de las siguientes 14 especies de Cactáceas del norte de Chile: Cumulopuntia sphaerica, Maihueniopsiscamachoi, Tunilla soehrensii, Echinopsis atacamensis, Echinopsis coquimbana, Haageocereus chilensis, Oreocereushempelianus, Oreocereus leucotrichus, Copiapoa coquimbana, Eriosyce aurata, Eriosyce subgibbosa, Eulychnia breviflora,Browningia candelaris y Corryocactus brevistylus. Los granos de polen de las especies de la subfamilia Opuntioideae sonesferoidales, apolares y periporados. Granos de la subfamilia Cactoideae son subesferoidales, isopolares y tricolpados yse pueden diferenciar taxonómicamente entre tribus. Los resultados indican que es posible diferenciar los granos de polende las Cactáceas a nivel de género pero que debido a la resolución taxonómica de este análisis, la determinación a nivel deespecie sería más complicada. Sin embargo, una colección de polen de referencia de cactáceas más amplia y considerandomás caracteres que los incluidos en este trabajo podrían mejorar este problema en el futuro

Suspended sediment load and bedload flux from the Glacier d'Otemma proglacial forefield (summers 2020 and 2021)

The Glacier d’Otemma proglacial margin, located in the Swiss Alps at an altitude of about 2450 m a.s.l. (45.93423 N, 7.41160 E), is characterized by a ca. 1 km long by 200 m wide active braided forefield. In this setting we installed two gauging stations for the monitoring of both suspended sediment and bedload transport within the proglacial margin: GS1 at about 350 m from the glacier terminus and GS2 at the forefield outlet. Monitoring stations were equipped with water pressure sensors (CS451 from Cambell Scientific), turbidity probes (OBS300+ from Cambell Scientific) and geophones (3-components PE-6/B from Sensor Nederland connected to a DiGOS DATA-CUBE type 2 logger). Water discharge were determined following modalities described in Müller and Miesen (2022). Suspended loads were quantified using a conventional turbidity-suspended sediment concentration relationship, while bedload transport was derived seismically using the geophysical Fluvial model inversion (FMI) algorithm developed in Dietze et al. (2018). The dataset covers summers 2020 and 2021. Further details on data aquisition and post-processing techniques are available in Mancini et al. (2023)

Evidence of glacier-permafrost interactions associated with hydro-geomorphological processes and landforms at Snøhetta, Dovrefjell, Norway

Glacier-permafrost interactions are investigated to understand glacial-hydrological influence along a partly glacierised valley on the NE flank of the Snøhetta massif, Dovrefjell, southern Norway. Of particular interest is how processes are controlled by a hydrological connection between landforms. Field mapping identified an ice-marginal landsystem comprising a polythermal glacier, a proglacial lake, an ice-cored moraine complex and a river-lake with perennial frost mounds. A clear interaction between glacial and periglacial processes was observed in transitional landforms, most prominently in the ice-cored moraine which constitutes a permafrost environment that is directly reworked by glaciofluvial processes. The role of this interaction in controlling seasonal, partial drainage of the proglacial lake was assessed using remote sensing-based observations of lake surface size evolution and seasonal surface subsidence. Results suggest a two-fold threshold for lake drainage: Depending on the dynamics of glacial discharge and active layer depth, the ice-cored moraine may either act as a barrier or a pathway to meltwater exiting the glacier. This demonstrates the importance of meltwater dynamics in controlling landform evolution in a glacial-periglacial landscape. To further assess the importance of surface and subsurface hydrology in linking glacial and periglacial domains, water stable oxygen isotope ratios across the study area were studied to map the flow of meltwater from glacier to permafrost. Results include a model of the surface and subsurface hydrology in the catchment and promote a conceptual understanding of water as a thermal, hydraulic and mechanical agent of transient glacier-permafrost interaction operating at heterogeneous timescales