Quantifying post-glacial erosion at the Gorner glacier, Switzerland, using OSL and 10Be surface exposure dating.

2020 ◽  
Author(s):  
Joanne Elkadi ◽  
Benjamin Lehmann ◽  
Georgina King ◽  
Olivia Steinemann ◽  
Susan Ivy-Ochs ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Cosmic Ray ◽  
Western Alps ◽  
Optically Stimulated Luminescence ◽  
Surface Erosion ◽  
Glacial Erosion ◽  
Surface Exposure Dating ◽  
Erosion Rates ◽  
Exposure Dating

<p>Quaternary erosion through glacial and post-glacial processes has left an imprint on Alpine topography. There are few methods capable of resolving these processes on Late glacial to Holocene timescales. The aim of this study is to contribute towards a more detailed understanding of post-glacial erosion across the Central and Western Alps by better constraining the post-glacial erosion history of the Gorner glacier in Zermatt, Switzerland. This is done using a new approach that combines Optically Stimulated Luminescence (OSL) and <sup>10</sup>Be cosmogenic nuclide surface exposure dating to invert for post-glacial erosion rates (Lehmann et al., 2019). Both dating methods are influenced by surface erosion but operate on different spatial scales- OSL signals form within the first 1-5 mm of a rock surface (Sohbati et al., 2011) whereas the <sup>10</sup>Be signal accumulates within approximately the first 3 m (Lal, 1991). Six bedrock samples, exposed progressively since the Last Glacial Maximum, were collected along a vertical transect spanning an elevation of 641 m. Preliminary results show inheritance in the bottom three samples suggesting multiple advances and retreat. Further results for the post-glacial erosion rates down the transect, and comparison to other glaciers in the Western Alps, will be presented.</p><p>References:</p><p>Lal, D., 1991. Cosmic ray labelling of erosion surfaces: in situ nuclide production rates and erosion models. Earth and Planetary Science Letters, 104, 424-439.</p><p>Lehmann, B et al., 2019. Evaluating post-glacial bedrock erosion and surface exposure duration by coupling in situ optically stimulated luminescence and <sup>10</sup>Be dating. Earth Surface Dynamics, 7.</p><p>Sohbati, R. et al., 2011. Investigating the resetting of OSL signals in rock surfaces. Geochronometria, 38(3), 249-258.</p>

Les nucleides cosmogeniques produits in-situ; de nouveaux outils en geomorphologie quantitative

2000 ◽  
Vol 171 (4) ◽  
pp. 383-396 ◽  
Author(s):  
Lionel L. Siame ◽  
Regis Braucher ◽  
Didier L. Bourles
Keyword(s):  
Cosmic Ray ◽  
Spatial Variations ◽  
Surface Exposure Dating ◽  
Exposure Dating ◽  
Mineral Fraction ◽  
Surficial Deposits ◽  
Geomorphic Processes ◽  
Quantitative Tool ◽  
In Situ Production

Abstract Measurement of 10 Be and 26 Al concentrations produced by cosmic ray bombardment within the quartz mineral fraction of surficial deposits and exposed bedrocks (in situ-production) is rapidly becoming an important quantitative tool in geomorphology. Whereas conventional methods provide age control on stratigraphic profiles, surface exposure dating using in situ-produced 10 Be and 26 Al is particularly well-suited not only for continuous dating but also for quantifying spatial variations and rates of geomorphic processes.

scholarly journals Postglacial erosion of bedrock surfaces and deglaciation timing: New insights from the Mont Blanc massif (western Alps)

Geology ◽  
2019 ◽  
Vol 48 (2) ◽  
pp. 139-144 ◽  
Author(s):  
Benjamin Lehmann ◽  
Frédéric Herman ◽  
Pierre G. Valla ◽  
Georgina E. King ◽  
Rabiul H. Biswas ◽  
...  
Keyword(s):  
Erosion Rate ◽  
Western Alps ◽  
Optically Stimulated Luminescence ◽  
European Alps ◽  
Erosion Rates ◽  
Exposure Dating ◽  
The Last Glacial Maximum ◽  
Mont Blanc Massif ◽  
The Last Glacial

Abstract Since the Last Glacial Maximum, ∼20 k.y. ago, Alpine glaciers have retreated and thinned. This transition exposed bare bedrock surfaces that could then be eroded by a combination of debuttressing or local frost cracking and weathering. Quantification of the respective contributions of these processes is necessary to understand the links between long-term climate and erosion in mountains. Here, we quantified the erosion histories of postglacial exposed bedrock in glacial valleys. Combining optically stimulated luminescence and terrestrial cosmogenic nuclide (TCN) surface exposure dating, we estimated the erosion rate of bedrock surfaces at time scales from 101 to 104 yr. Bedrock surfaces sampled from the flanks of the Mer de Glace (Mont Blanc massif, European Alps) revealed erosion rates that vary from 3.5 ± 1.2 ⋅ 10−3 mm/yr to 4.3 ± 0.6 mm/yr over ∼500 m of elevation, with a negative correlation between erosion rate and elevation. The observed spatial variation in erosion rates, and their high values, reflect morphometric (elevation and surface slope) and climatic (temperature and snow cover) controls. Furthermore, the derived erosion rates can be used to correct the timing of deglaciation based on TCN data, potentially suggesting very rapid ice thinning during the Gschnitz stadial.

scholarly journals Evaluating post-glacial bedrock erosion and surface exposure duration by coupling in situ optically stimulated luminescence and <sup>10</sup>Be dating

2019 ◽  
Vol 7 (3) ◽  
pp. 633-662 ◽  
Author(s):  
Benjamin Lehmann ◽  
Frédéric Herman ◽  
Pierre G. Valla ◽  
Georgina E. King ◽  
Rabiul H. Biswas
Keyword(s):  
Exposure Duration ◽  
Numerical Approach ◽  
Optically Stimulated Luminescence ◽  
Surface Erosion ◽  
Erosion Rates ◽  
Exposure Dating ◽  
Quaternary Glaciation ◽  
Bedrock Erosion ◽  
Bedrock Surface ◽  
The Impact

Abstract. Assessing the impact of Quaternary glaciation at the Earth's surface implies an understanding of the long-term evolution of alpine landscapes. In particular, it requires simultaneous quantification of the impact of climate variability on past glacier fluctuations and on bedrock erosion. Here we present a new approach for evaluating post-glacial bedrock surface erosion in mountainous environments by combining terrestrial cosmogenic nuclide 10Be (TCN) and optically stimulated luminescence (OSL) surface exposure dating. Using a numerical approach, we show how it is possible to simultaneously invert bedrock OSL signals and 10Be concentrations into quantitative estimates of post-glacial exposure duration and bedrock surface erosion. By exploiting the fact that OSL and TCN data are integrated over different timescales, this approach can be used to estimate how bedrock erosion rates vary spatially and temporally since glacier retreat in an alpine environment.

scholarly journals Evaluating optically stimulated luminescence rock surface exposure dating as a novel approach for reconstructing coastal boulder movement on decadal to centennial timescales

2021 ◽  
Vol 9 (2) ◽  
pp. 205-234
Author(s):  
Dominik Brill ◽  
Simon Matthias May ◽  
Nadia Mhammdi ◽  
Georgina King ◽  
Benjamin Lehmann ◽  
...  
Keyword(s):  
Optically Stimulated Luminescence ◽  
Local Source ◽  
Rock Surface ◽  
Surface Exposure Dating ◽  
Erosion Rates ◽  
Exposure Dating ◽  
Relative Chronology ◽  
Novel Approach ◽  
Exposure Ages ◽  
Boulder Deposits

Abstract. Wave-transported boulders represent important records of storm and tsunami impact over geological timescales. Their use for hazard assessment requires chronological information on their displacement that in many cases cannot be achieved by established dating approaches. To fill this gap, this study investigated, for the first time, the potential of optically stimulated luminescence rock surface exposure dating (OSL-RSED) for estimating cliff-detachment ages of wave-transported coastal boulders. The approach was tested on calcarenite clasts at the Rabat coast, Morocco. Calibration of the OSL-RSED model was based on samples with rock surfaces exposed to sunlight for ∼ 2 years, and OSL exposure ages were evaluated against age control deduced from satellite images. Our results show that the dating precision is limited for all targeted boulders due to the local source rock lithology which has low amounts of quartz and feldspar. The dating accuracy may be affected by erosion rates on boulder surfaces of 0.02–0.18 mm yr−1. Nevertheless, we propose a robust relative chronology for boulders that are not affected by significant post-depositional erosion and that share surface angles of inclination with the calibration samples. The relative chronology indicates that (i) most boulders were detached from the cliff by storm waves; (ii) these storms lifted boulders with masses of up to ∼ 24 t; and (iii) the role of storms in the formation of boulder deposits along the Rabat coast is more significant than previously assumed. Although OSL-RSED cannot provide reliable absolute exposure ages for the coastal boulders in this study, the approach has large potential for boulder deposits composed of rocks with larger amounts of quartz or feldspar and less susceptibility to erosion.

Reconstructing the Timing of Flash Floods Using 10Be Surface Exposure Dating at Leidy Creek Alluvial Fan and Valley, White Mountains, California–Nevada, USA

2015 ◽  
Vol 83 (1) ◽  
pp. 178-186 ◽  
Author(s):  
Markus Fuchs ◽  
Rebecca Reverman ◽  
Lewis A. Owen ◽  
Kurt L. Frankel
Keyword(s):  
Flash Floods ◽  
Alluvial Fan ◽  
Optically Stimulated Luminescence ◽  
Alluvial Fans ◽  
White Mountains ◽  
The Holocene ◽  
Surface Exposure Dating ◽  
Exposure Dating ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods

AbstractLarge alluvial fans characterize the piedmonts of the White Mountains, California–Nevada, USA, with large boulders strewn across their surfaces. The boulders are interpreted as flash floods deposits with an unclear trigger for the transport process. Several triggers are possible, including glacial lake outburst floods (GLOFs), thunderstorms or rainfall on snow cover. From a paleoenvironmental perspective, the origin of the flash floods is of fundamental importance. The alluvial fans that flank the White Mountains at Leidy Creek display particularly impressive examples of these deposits. The boulder deposits and the source catchment at Leidy Creek were examined using 10Be terrestrial cosmogenic nuclide (TCN) surface exposure dating to help elucidate their age and origin. All boulders dated on the alluvial fans date to the Holocene. This is in accordance with the geomorphic analyses of the Leidy Creek catchment and its terraces and sediment ridges, which were also dated to the Holocene using optically stimulated luminescence (OSL) and 10Be surface exposure. The results suggest that the boulders on the alluvial fan were deposited by flash floods during thunderstorm events affecting the catchment of the Leidy Creek valley. Paleomonsoonal-induced mid-Holocene flash floods are the most plausible explanation for the discharges needed for these boulder aggradations, but a regional dataset is needed to confirm this explanation.

Surface exposure dating by in-situ produced cosmogenic nuclides: chemical mineral separation of purified quartz

2001 ◽  
Vol 89 (11-12) ◽  
Author(s):  
M. Altmaier ◽  
W. Klas ◽  
U. Herpers
Keyword(s):  
Cosmic Radiation ◽  
Cosmogenic Nuclides ◽  
Surface Exposure Dating ◽  
Exposure Dating ◽  
Mineral Separation

The interaction of cosmic radiation with terrestrial matter leads to the

Cosmogenic Be-10 surface exposure data from the Sub-Antarctic Kerguelen Archipelago

2020 ◽  
Author(s):  
Henriette Linge ◽  
Jostein Bakke ◽  
Talin Tuestad ◽  
Philip Deline ◽  
Ludovic Ravanel ◽  
...  
Keyword(s):  
Hydrothermal Fluids ◽  
Large Igneous Province ◽  
Geochemical Composition ◽  
Surface Exposure Dating ◽  
Exposure Dating ◽  
Ice Cap ◽  
Wide Range ◽  
Exposure Ages ◽  
Kerguelen Archipelago

&lt;p&gt;The Kerguelen archipelago (around 49&amp;#176;S 69&amp;#176;E) is the emerged part of the Kerguelen Plateau, a large igneous province in the southwestern Indian Ocean. Information on past climatic and environmental conditions in the region is vital for understanding the past behaviour of the southern westerly winds. The cross-disciplinary project SOUTHSPERE seeks to investigate past variations in this weather system through reconstruction of temporal and spatial glacier variability from lake records and glacial landforms N and NE of the Cook Ice Cap. Reliable and accurate chronological control is crucial in this context.&lt;/p&gt;&lt;p&gt;Surface exposure dating of glacial geomorphological features S and SE of the Cook Ice Cap has previously been done using in situcosmogenic Cl-36 [1, 2]. Solifluction and gelifraction processes appear very active in our field area, as do aeolian erosion. Also, highly variable geochemical composition of the basalts and associated intrusions, as well as the degree and type of metamorphosis, lead to strong lithology-dependant weathering and erosion rates, as evident from differential weathering reliefs on cm and m scales. The very active surface environment constitutes a challenge for obtaining accurate surface exposure ages.&lt;/p&gt;&lt;p&gt;In the NW part of the archipelago, basaltic lava units altered by meteoric-hydrothermal fluids contain a wide variety of secondary silicate and carbonate minerals [3]. In settings where quartz-filled geodes and fractures in the basalt are located in favourable positions on bedrock and boulder surfaces, analysis of Be-10 in euhedral and microcrystalline quartz offers a means of validating in situ Cl-36 surface exposure ages. Moreover, multi-nuclide analysis would open up for a wide range of process and landscape development studies on this young archipelago. Percolation of hydrothermal fluids in fractures and geodes is probably related to the intrusion of younger (15-5 Ma) subvolcanic rocks [see 3 and references therein]. A meteoric source of the fluids would imply that the secondary silicates contain meteoric Be-10. As meteoric production is greater than in situ production, this may represent a problem for utilising in situ Be-10 for surface exposure dating. If secondary silicate formation occurred early, rather than late in the intrusive phase, complete radioactive decay of the meteoric Be-10 component is expected prior to surface exposure.&lt;/p&gt;&lt;p&gt;110 rock samples were collected for surface exposure dating with in situ cosmogenic nuclides during a field campaign in November and December 2019. Here we present the first Be-10 data from rock surfaces of glacially transported boulders and exposed bedrock.&lt;/p&gt;&lt;p&gt;[1] Jomelli et al. 2017. Quaternary Science Reviews 162, 128-144.&lt;/p&gt;&lt;p&gt;[2] Jomelli et al. 2018. Quaternary Science Reviews 183, 110-123.&lt;/p&gt;&lt;p&gt;[3] Renac et al. 2010. European Journal of Mineralogy 22, 215-234.&lt;/p&gt;

Area-representative validation of remotely sensed high resolution soil moisture using a cosmic-ray neutron sensor

2020 ◽  
Author(s):  
Dragana Panic ◽  
Isabella Pfeil ◽  
Andreas Salentinig ◽  
Mariette Vreugdenhil ◽  
Wolfgang Wagner ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Root Zone ◽  
Spatial Scales ◽  
Temporal Frequency ◽  
Cosmic Ray ◽  
Irrigation Scheduling ◽  
Water Index ◽  
The Impact

&lt;p&gt;Reliable measurements of soil moisture (SM) are required for many applications worldwide, e.g., for flood and drought forecasting, and for improving the agricultural water use efficiency (e.g., irrigation scheduling). For the retrieval of large-scale SM datasets with a high temporal frequency, remote sensing methods have proven to be a valuable data source. (Sub-)daily SM is derived, for example, from observations of the Advanced Scatterometer (ASCAT) since 2007. These measurements are available on spatial scales of several square kilometers and are in particular useful for applications that do not require fine spatial resolutions but long and continuous time series. Since the launch of the first Sentinel-1 satellite in 2015, the derivation of SM at a spatial scale of 1 km has become possible for every 1.5-4 days over Europe (SSM1km) [1]. Recently, efforts have been made to combine ASCAT and Sentinel-1 to a Soil Water Index (SWI) product, in order to obtain a SM dataset with daily 1 km resolution (SWI1km) [2]. Both datasets are available over Europe from the Copernicus Global Land Service (CGLS, https://land.copernicus.eu/global/). As the quality of such a dataset is typically best over grassland and agricultural areas, and degrades with increasing vegetation density, validation is of high importance for the further development of the dataset and for its subsequent use by stakeholders.&lt;/p&gt;&lt;p&gt;Traditionally, validation studies have been carried out using in situ SM sensors from ground networks. Those are however often not representative of the area-wide satellite footprints. In this context, cosmic-ray neutron sensors (CRNS) have been found to be valuable, as they provide integrated SM estimates over a much larger area (about 20 hectares), which comes close to the spatial support area of the satellite SM product. In a previous study, we used CRNS measurements to validate ASCAT and S1 SM over an agricultural catchment, the Hydrological Open Air Laboratory (HOAL), in Petzenkirchen, Austria. The datasets were found to agree, but uncertainties regarding the impact of vegetation were identified.&lt;/p&gt;&lt;p&gt;In this study, we validated the SSM1km, SWI1km and a new S1-ASCAT SM product, which is currently developed at TU Wien, using CRNS. The new S1-ASCAT-combined dataset includes an improved vegetation parameterization, trend correction and snow masking. The validation has been carried out in the HOAL and on a second site in Marchfeld, Austria&amp;#8217;s main crop producing area. As microwaves only penetrate the upper few centimeters of the soil, we applied the soil water index concept [3] to obtain soil moisture estimates of the root zone (approximately 0-40 cm) and thus roughly corresponding to the depth of the CRNS measurements. In the HOAL, we also incorporated in-situ SM from a network of point-scale time-domain-transmissivity sensors distributed within the CRNS footprint. The datasets were compared to each other by calculating correlation metrics. Furthermore, we investigated the effect of vegetation on both the satellite and the CRNS data by analyzing detailed information on crop type distribution and crop water content.&lt;/p&gt;&lt;p&gt;[1] Bauer-Marschallinger et al., 2018a: https://doi.org/10.1109/TGRS.2018.2858004&lt;br&gt;[2] Bauer-Marschallinger et al., 2018b: https://doi.org/10.3390/rs10071030&lt;br&gt;[3] Wagner et al., 1999: https://doi.org/10.1016/S0034-4257(99)00036-X&lt;/p&gt;

scholarly journals Optically stimulated luminescence (OSL) as a chronometer for surface exposure dating

2012 ◽  
Vol 117 (B9) ◽  
Author(s):  
Reza Sohbati ◽  
Andrew S. Murray ◽  
Melissa S. Chapot ◽  
Mayank Jain ◽  
Joel Pederson
Keyword(s):  
Optically Stimulated Luminescence ◽  
Surface Exposure Dating ◽  
Exposure Dating

scholarly journals OSL rock surface exposure dating as a novel approach for reconstructing transport histories of coastal boulders over decadal to centennial timescales

2020 ◽  
Author(s):  
Dominik Brill ◽  
Simon Matthias May ◽  
Nadia Mhammdi ◽  
Georgina King ◽  
Christoph Burow ◽  
...  
Keyword(s):  
Local Source ◽  
Rock Surface ◽  
Surface Exposure Dating ◽  
Erosion Rates ◽  
Exposure Dating ◽  
Relative Chronology ◽  
Novel Approach ◽  
Calibration Samples ◽  
Exposure Ages ◽  
Boulder Deposits

Abstract. Wave-transported boulders represent important records of storm and tsunami impact over geological timescales. Their use for hazard assessment requires chronological information that in many cases cannot be achieved by established dating approaches. To fill this gap, this study investigated, for the first time, the potential of optically stimulated luminescence rock surface exposure dating (OSL-RSED) for estimating transport ages of wave-emplaced coastal boulders. The approach was applied to calcarenite clasts at the Rabat coast, Morocco. Calibration of the OSL-RSED model was based on samples with rock surfaces exposed to sunlight for ~ 2 years, and OSL exposure ages were evaluated against age control deduced from satellite images. Our results show that the dating precision is limited for all boulders due to the local source rock lithology which has low amounts of quartz and feldspar. The dating accuracy may be affected by erosion rates on boulder surfaces of 0.06–0.2 mm/year. Nevertheless, we propose a robust relative chronology for boulders that are not affected by significant post-depositional erosion and that share surface angles of inclination with the calibration samples. The relative chronology indicates that (i) most boulders were moved by storm waves; (ii) these storms lifted boulders with masses of up to ~ 40 t; and (iii) the role of storms for the formation of boulder deposits along the Rabat coast is much more significant than previously assumed. Although OSL-RSED cannot provide reliable absolute exposure ages for the coastal boulders in this study, the approach has large potential for boulder deposits composed of rocks with larger amounts of quartz or feldspar, older formation histories and less susceptibility to erosion.

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