6 results on '"Schlunegger, F."'
Search Results
2. Making stratigraphy in the Anthropocene: climate change impacts and economic conditions controlling the supply of sediment to Lake Geneva
- Author
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Lane, S. N., Bakker, M., Costa, A., Girardclos, S., Loizeau, J.-L., Molnar, P., Silva, T., Stutenbecker, L., and Schlunegger, F.
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ddc:333.7-333.9 ,Multidisciplinary ,Stratigraphy ,lcsh:R ,lcsh:Medicine ,Geomorphology ,Sedimentology ,Article ,Core dating ,Limnology ,Anthropocene ,ddc:550 ,Climate change ,Glocalization ,Sediment ,lcsh:Q ,Hydrology ,lcsh:Science ,Climate-change impacts ,Sediment accumulation rate ,550 Earth sciences & geology - Abstract
The Anthropocene has been proposed as a profound, globally synchronous rupture in the history of the Earth System with its current state fundamentally different to that of the Holocene and driven by the geological force of human activity. Here, we show how stratigraphy is being made in a lake that is heavily impacted upon by climate change and human activities. For one of the largest inner-Alpine catchments in the European Alps, we draw attention to how sedimentation rates are a product of non-stationary, reflexive, human actions. In Lake Geneva, we identify both a human-induced climate change (HCC) signature and the effects of a recent economic shock on sediment extraction upon sediment loading to and sedimentation rates in the lake. The HCC signature thus reflects the nature of climate change impacts in this basin, where sediment accumulation rates evolve with climate, but where economic conditions contribute to shifts in the supply of sediment to the lake. Following social theory, we call this glocalization because of the combined importance and inseparability of human impacts across different spatial scales. The nature of human impacts on sediment delivery to the lake mean that the influence of humans is unlikely to be captured in the long-term depositional record. ISSN:2045-2322
- Published
- 2019
3. Complex geomorphologic assemblage of terrains in association with the banded terrain in Hellas basin, Mars.
- Author
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Diot, X., El-Maarry, M.R., Schlunegger, F., Norton, K.P., Thomas, N., Grindrod, P.M., and Chojnacki, M.
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GEOMORPHOLOGY , *SEDIMENTATION & deposition , *EROSION , *HELLAS Planitia (Mars) , *EARTH'S mantle - Abstract
Hellas basin acts as a major sink for the southern highlands of Mars and is likely to have recorded several episodes of sedimentation and erosion. The north-western part of the basin displays a potentially unique Amazonian landscape domain in the deepest part of Hellas, called “banded terrain”, which is a deposit characterized by an alternation of narrow band shapes and inter-bands displaying a sinuous and relatively smooth surface texture suggesting a viscous flow origin. Here we use high-resolution (HiRISE and CTX) images to assess the geomorphological interaction of the banded terrain with the surrounding geomorphologic domains in the NW interior of Hellas to gain a better understanding of the geological evolution of the region as a whole. Our analysis reveals that the banded terrain is associated with six geomorphologic domains: a central plateau named Alpheus Colles, plain deposits (P1 and P2), reticulate (RT1 and RT2) and honeycomb terrains. Based on the analysis of the geomorphology of these domains and their cross-cutting relationships, we show that no widespread deposition post-dates the formation of the banded terrain, which implies that this domain is the youngest and latest deposit of the interior of Hellas. Therefore, the level of geologic activity in the NW Hellas during the Amazonian appears to have been relatively low and restricted to modification of the landscape through mechanical weathering, aeolian and periglacial processes. Thermophysical data and cross-cutting relationships support hypotheses of modification of the honeycomb terrain via vertical rise of diapirs such as ice diapirism, and the formation of the plain deposits through deposition and remobilization of an ice-rich mantle deposit. Finally, the observed gradual transition between honeycomb and banded terrain suggests that the banded terrain may have covered a larger area of the NW interior of Hellas in the past than previously thought. This has implications on the understanding of the evolution of the deepest part of Hellas. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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4. The geomorphology and morphometry of the banded terrain in Hellas basin, Mars.
- Author
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Diot, X., El-Maarry, M.R., Schlunegger, F., Norton, K.P., Thomas, N., and Grindrod, P.M.
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GEOMORPHOLOGY , *GEOLOGICAL basins , *MARTIAN craters , *HIGH resolution imaging , *VISCOUS flow , *MARTIAN atmosphere - Abstract
Hellas basin is a large impact basin situated in the southern highlands of Mars. The north-western part of the basin has the lowest elevation (−7.5 km) on the planet and contains a possibly unique terrain type, which we informally call “banded terrain”. The banded terrain is made up of smooth-looking banded deposits that display signs of viscous behavior and a paucity of superimposed impact craters. In this study, we use newly acquired high spatial resolution images from the High Resolution Imaging Science Experiment (HiRISE) in addition to existing datasets to characterize the geomorphology, the morphometry and the architecture of the banded terrain. The banded terrain is generally confined to the NW edge of the Alpheus Colles plateau. The individual bands are ~3–15 km-long, ~0.3 km-wide and are separated by narrow inter-band depressions, which are ~65 m-wide and ~10 m-deep. The bands display several morphologies that vary from linear to concentric forms. Morphometric analysis reveals that the slopes along a given linear or lobate band ranges from 0.5° to 15° (average ~6°), whereas the concentric bands are located on flatter terrain (average slope ~2–3°). Crater-size frequency analysis yields an Amazonian-Hesperian boundary crater retention age for the terrain (~3 Gyr), which together, with the presence of very few degraded craters, either implies a recent emplacement, resurfacing, or intense erosion. The apparent sensitivity to local topography and preference for concentrating in localized depressions is compatible with deformation as a viscous fluid. In addition, the bands display clear signs of degradation and slumping at their margins along with a suite of other features that include fractured mounds, polygonal cracks at variable size-scales, and knobby/hummocky textures. Together, these features suggest an ice-rich composition for at least the upper layers of the terrain, which is currently being heavily modified through loss of ice and intense weathering, possibly by wind. [ABSTRACT FROM AUTHOR]
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- 2014
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5. Quantifying sediment supply at the end of the last glaciation: Dynamic reconstruction of an alpine debris-flow fan
- Author
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Peter W. Kubik, Kevin Norton, Naki Akçar, Sara Savi, Romain Delunel, Fritz Schlunegger, Vincenzo Picotti, Francesco Brardinoni, Savi S, Norton K, Picotti V, Akçar N, Delunel R, Brardinoni F, Kubik P, Schlunegger F, Savi, S, Norton, K, Picotti, V, Akçar, N, Delunel, R, Brardinoni, F, Kubik, P, and Schlunegger, F
- Subjects
geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,GEO/04 - GEOGRAFIA FISICA E GEOMORFOLOGIA ,Alluvial fan ,Last Glacial Maximum ,Geology ,010502 geochemistry & geophysics ,01 natural sciences ,Debris flow ,Paraglacial ,Denudation ,13. Climate action ,Interglacial ,Glacial period ,Institut für Geowissenschaften ,Geomorphology ,Holocene ,0105 earth and related environmental sciences - Abstract
In this paper we quantify the sediment dynamics in the formerly glaciated Ziel- bach catchment in the Italian Alps from the end of the Last Glacial Maximum (LGM) until today. As a basis for our quantifica- tion, we use the stratigraphic record offered by a 3.5 km2 large fan that we explore with a seismic survey, stratigraphic analyses of drillhole material, and 14C ages measured on organic matter encountered in these drill- ings. In addition, we calculate past denuda- tion rate variability in the fan deposits using concentrations of cosmogenic 10Be. We merge this information into a scenario of how the sediment flux has changed through time and how this variability can be related to cli- matic variations, framed within well-known paraglacial models. The results document a highly complex natural system. From the LGM to the very early Holocene, ice-melted discharge and climate variability promoted a high sediment flux (sedimentation rate up to 40 mm/yr). This flux then dramatically decreased toward interglacial values (0.8 mm/yr at 5–4 calibrated kyr B.P.). However, in contrast to the trend of classic paraglacial models, the flux recorded at Zielbach shows secondary peaks at 6.5 ka and 2.5 ka, with values of 13 mm/yr and 1.5 mm/yr, respec- tively. Paleo-denudation rates also decrease from ~33 mm/yr at the beginning of the Holocene to 0.42 mm/yr at 5 ka, with peaks of ~6 mm/yr and 1.1 mm/yr at 6.5 ka and 2.5 ka. High-amplitude climate change is the most likely cause of the secondary peaks, but anthropogenic activities may have contrib- uted as well. The good correlation between paleo-sedimentation and paleo-denudation rates suggests that the majority of the degla- ciated material destocked from the Zielbach catchment is stored in the alluvial fan. In this paper we quantify the sediment dynamics in the formerly glaciated Zielbach catchment in the Italian Alps from the end of the Last Glacial Maximum (LGM) until today. As a basis for our quantification, we use the stratigraphic record offered by a 3.5 km2 large fan that we explore with a seismic survey, stratigraphic analyses of drillhole material, and 14C ages measured on organic matter encountered in these drillings. In addition, we calculate past denudation rate variability in the fan deposits using concentrations of cosmogenic 10Be. We merge this information into a scenario of how the sediment flux has changed through time and how this variability can be related to climatic variations, framed within well-known paraglacial models. The results document a highly complex natural system. From the LGM to the very early Holocene, ice-melted discharge and climate variability promoted a high sediment flux (sedimentation rate up to 40 mm/yr). This flux then dramatically decreased toward interglacial values (0.8 mm/yr at 5-4 calibrated kyr B.P.). However, in contrast to the trend of classic paraglacial models, the flux recorded at Zielbach shows secondary peaks at 6.5 ka and 2.5 ka, with values of 13 mm/yr and 1.5 mm/yr, respectively. Paleo-denudation rates also decrease from ̃33 mm/yr at the beginning of the Holo cene to 0.42 mm/yr at 5 ka, with peaks of ̃6 mm/yr and 1.1 mm/yr at 6.5 ka and 2.5 ka. High-amplitude climate change is the most likely cause of the secondary peaks, but anthro pogenic activities may have contributed as well. The good correlation between paleo-sedimentation and paleo-denudation rates suggests that the majority of the deglaciated material destocked from the Zielbach catchment is stored in the alluvial fan. © 2014 Geological Society of America.
- Published
- 2014
6. Combining amphibious geomorphology with subsurface geophysical and geological data: A neotectonic study at the front of the Alps (Bernese Alps, Switzerland).
- Author
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Fabbri, S.C., Herwegh, M., Horstmeyer, H., Hilbe, M., Hübscher, C., Merz, K., Schlunegger, F., Schmelzbach, C., Weiss, B., and Anselmetti, F.S.
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GEOLOGIC faults , *NEOTECTONICS , *FAULT zones , *EARTHQUAKES , *GEOMORPHOLOGY , *SEISMOLOGY , *NORMAL faults (Geology) - Abstract
In the vicinity of Lake Thun at the front of the Bernese Alps (Switzerland), we performed a multidisciplinary neotectonic study combining onshore and offshore geological data and geophysical measurements in order to identify potentially active fault structures. Paleoseismic reconstructions on the northern margin of the Alps have documented several strong earthquakes with moment magnitudes ≥6 during the Late Quaternary, which have long recurrence intervals of 1,000 to 2,000 years. Such earthquakes are expected to produce surface ruptures. In this light, we investigated the study area located near Lake Thun primarily for on-fault evidence, to date still a shortcoming in Switzerland. We detected several features indicating potential fault activity, such as aligned subaquatic morphological depressions, offset horizons observed in reflection seismic profiles of lake sediments and in ground-penetrating radar images, all delineating a fault trace. Observations of fluvial deposits in a nearby gravel pit in the prolongation of the inferred structure supports these findings. A narrow zone with rotated long axes of pebbles (inclining at ∼60°) is clearly distinguishable and crosscuts the original bedding with predominantly horizontal orientation of pebble axes. This zone further shows an apparent 1.1 m offset of oxidized horizons and is therefore considered as a potential fault plane in a normal faulting regime. A dated radiocarbon age of ∼11,000 years BP of the gravel deposits hence suggests a younger fault activity during the Holocene. The Einigen Fault Zone (EFZ), proposed on the basis of these observations, is considered as a complex fault system with a combination of dextral strike-slip and normal faulting, as suggested by GPR images. Observations in the gravel pit and radar data independently show that it includes at least two fault strands. However, while five earthquakes with epicentral intensities I 0 ≥ VI and numerous smaller seismic events are known within less than 30 km epicentral distance to Lake Thun over the past 400 years, none of these seem to coincide with the location of the EFZ. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
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