185 results on '"Spagnolo, Matteo"'
Search Results
152. Geomorphic evolution of the seaward escarpment in the NE Ligurian Alps (Italy)
- Author
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Spagnolo, Matteo, primary and Firpo, Marco, additional
- Published
- 2007
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153. Last Glacial Maximum and the Gschnitz stadial in the Maritime Alps according to 10 Be cosmogenic dating.
- Author
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Federici, Paolo Roberto, Granger, Darryl E., Ribolini, Adriano, Spagnolo, Matteo, Pappalardo, Marta, and Cyr, Andrew J.
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LAST Glacial Maximum ,CLIMATE change ,COMPARATIVE studies ,PALEOCLIMATOLOGY ,GLACIERS ,ATMOSPHERIC circulation - Abstract
Two glacial deposits in the Gesso valley ( Maritime, Alps) have been
10 Be-dated at 20 140±1080 (weighted mean± SD) and 16 590±970 years, respectively, thus constraining the Last Glacial Maximum ( LGM) and Gschnitz stadials in the southwestern part of the Alps. The LGM age is chronologically coherent with MIS 2 and synchronous with most other LGM moraines in the Alps. The Gschnitz stadial also appears to be in agreement with the ages obtained from other Alpine sites and with Heinrich Event I. This suggests that the Alpine glaciers reacted simultaneously and essentially synchronously with the climate change associated with Heinrich Event 1. The Equilibrium Line Altitudes ( ELAs) of the LGM and Gschnitz reconstructed palaeoglaciers are 1850 and 1910 m a.s.l., respectively. The ELA comparison across the Alps indicates that the palaeoclimate of the Maritime Alps during the LGM was rather different from that of other Alpine sectors. However, the similar Gschnitz ELA value between the Gesso valley and other sites across the mountain chain indicates that Alpine glaciers responded with the same intensity to the climate change associated with Heinrich Event I. Overall, these results suggest that the interaction between the atmospheric circulation of air masses and local Alpine orography was more complex than has previously been argued. [ABSTRACT FROM AUTHOR]- Published
- 2012
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154. Exposure age dating and Equilibrium Line Altitude reconstruction of an Egesen moraine in the Maritime Alps, Italy.
- Author
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FEDERICI, PAOLO ROBERTO, GRANGER, DARRYL E., PAPPALARDO, MARTA, RIBOLINI, ADRIANO, SPAGNOLO, MATTEO, and CYR, ANDREW J.
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MORAINES ,GLACIAL landforms ,GLACIERS ,YOUNGER Dryas - Abstract
Four boulder samples from the Piano del Praiet frontal moraine in the Gesso della Barra Valley (Maritime Alps) have been
10 Be dated. The results give a weighted mean age of 11 340±370 (870) yr, constraining the frontal moraine to the Egesen glacial stadial, during the Younger Dryas cold phase. By applying the same10 Be production rate to other Egesen moraines previously dated in the Alps, we obtain similar ages for all of them. This suggests a synchroneity of the Egesen deglaciation in the European Alps at the end of the Younger Dryas. From the palaeoshape of the Egesen glacier, reconstructed by means of geomorphological mapping, an Equilibrium Line Altitude depression (δELA) of −520 to −530 m, with respect to the present-day ELA, and of −260 to −320 m, with respect to the Little Ice Age ELA, has been calculated. Comparison with other Alpine sector δELAs indicates that the Maritime Alps experienced humid climatic conditions during the Younger Dryas. [ABSTRACT FROM AUTHOR]- Published
- 2008
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- View/download PDF
155. The application of millimetre-wave radar to the study of the cryosphere
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Harcourt, William David, Robertson, Duncan Alexander, Macfarlane, David G., Rea, Brice R., Spagnolo, Matteo, and Benn, Douglas I.
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Radar ,Close range sensing ,Remote sensing ,Glaciology ,Snow dynamics ,Arctic ,Point clouds - Abstract
This thesis develops the technique of millimetre-wave radar at 94 GHz for close-range remote sensing of glaciers and terrestrial snow cover (the cryosphere). The capabilities of 94 GHz radar for cryosphere mapping are demonstrated using the 2ⁿᵈ generation All-weather Volcano Topography Imaging Sensor (AVTIS2), which maps 3D terrain from real-beam scanning. AVTIS2 acquires 3D point clouds of terrain and a comparison to co-located high density point clouds derived from Terrestrial Laser Scanner (TLS) data showed that AVTIS2 point cloud uncertainties were 1.5 m at 1.5 km and 3 m at 3 km. These values are smaller than other close-range radar systems used to map cryospheric terrain in 3D. Next, the distribution of Normalised Radar Cross Section (σ⁰) values over glacier ice at 94 GHz was found to be −17.0 < σ⁰ < −3.4; σ⁰ₘₑₐₙ = −9.9 dB and followed a log-normal distribution. These values are comparable to other terrain types at 94 GHz such as refrozen snow, wet snow and wet soil, hence glacier surfaces were found to be suitable targets for terrain mapping at 94 GHz. These fundamental results were used to apply the AVTIS2 94 GHz radar for monitoring snow cover and glacier calving. Field trials in Scotland showed that the transition of wet snow to a refrozen snowpack in response to reductions in air temperature could be detected from changes in 94 GHz σ⁰. Snow hazard features could also be identified, such as post-avalanche debris accumulations which manifest as localised increases in radar backscatter. Next, 3D AVTIS2 data was used to quantify glacier calving rates at the Hansbreen tidewater glacier in Svalbard. A time series of ice cliff morphology derived from the AVTIS2 3D data sets exposed the role of melt undercutting and demonstrated the critical role of the ocean on calving processes in Svalbard. The high accuracy 3D data acquired from AVTIS2 and the sensitivity of radar backscatter to surface changes has demonstrated the unique capabilities of 94 GHz radar for cryosphere mapping, paving the way forward for new applications and opportunities for close-range remote sensing of the cryosphere.
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- 2023
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156. Cool deltas. Sedimentary environments of Salpausselka I and II moraine ridges near Lahti, Finland.
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Kurjanski, Bartosz, Rea, Brice, Spagnolo, Matteo, Cornwell, David, Howell, John, and Palmu, Jukka-Pekka
- Published
- 2019
157. Global glacial geomorphology.
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Ely, Jeremy, Clark, Chris, Stokes, Chris, and Spagnolo, Matteo
- Published
- 2019
158. MLTWA and Attenuation mapping of Mount St. Helens (Washington, USA).
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Gabrielli, Simona, De Siena, Luca, Spagnolo, Matteo, and Del Pezzo, Edoardo
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- 2019
159. Analysing climatic influence on modern cirque equilibrium-line altitude, southern Scandinavia.
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Oien, Rachel, Spagnolo, Matteo, Rea, Brice, Bingham, Robert, and Barr, Iestyn
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CLIMATE sensitivity , *ALTITUDES - Published
- 2018
160. Glacier extent and climate in the Maritime Alps during the Younger Dryas.
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Spagnolo, Matteo and Ribolini, Adriano
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YOUNGER Dryas , *MARINE west coast climate , *ALPINE glaciers ,GLACIERS & climate - Published
- 2018
161. Geomorphological Map of Mount St. Helens volcano (Washington, USA).
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Gabrielli, Simona, Spagnolo, Matteo, and De Siena, Luca
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VOLCANOES - Published
- 2018
162. Diverse landscapes beneath Pine Island Glacier influence ice flow.
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Bingham, Robert G., Vaughan, David G., King, Edward C., Davies, Damon, Cornford, Stephen L., Smith, Andrew M., Arthern, Robert J., Brisbourne, Alex M., De Rydt, Jan, Graham, Alastair G. C., Spagnolo, Matteo, Marsh, Oliver J., and Shean, David E.
- Published
- 2018
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163. East Greenland lake sediments capture surface process response to Holocene climate transitions.
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van der Bilt, Willem, Rea, Brice, Spagnolo, Matteo, Roerdink, Desiree, Jørgensen, Steffen, Møller, Tor Einar, and Bakke, Josten
- Published
- 2018
164. The initiation and growth of glacial cirques: Insights from Britain and Ireland.
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Ely, Jeremy, Barr, Iestyn, Evans, Ian, and Spagnolo, Matteo
- Published
- 2018
165. Glacigenic reservoirs characterisation using sedimentology, geomorphology and virtual outcrop mapping.
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Kurjanski, Bartosz, Rea, Brice, Spagnolo, Matteo, Cornwell, David, and Howell, John
- Published
- 2018
166. Glacier equilibrium-line altitude as a tool to understand past and present climate
- Author
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Oien, Rachel Passig, Spagnolo, Matteo, Rea, Brice R., Barr, Iestyn D., and Bingham, Robert G.
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Cirques (Glacial landforms) ,Climatology - Abstract
Glacial cirques throughout history give the alpine landscapes dimension. Over the past century, glaciologists have attempted to unravel the secrets behind the climate topography-glacier relationship which is evident. This thesis is a study written as journal articles in multiple parts which investigate the climatic relationship between cirques through their equilibrium line altitudes (ELAs) from extant to palaeo. Due to the time transgressive nature of cirques and their geomorphic formation through multiple glacial cycles, the question remains, what climatic relationship can be deduced from these geomorphic features? In this thesis, I compare equilibrium-line altitudes (ELAs) derived from satellite imagery using a GIS toolbox and apply the Area-Altitude Balance Ratio (AABR) and Accumulation-Area Ratio (AAR) compared to field measurements on the glacier. Using a worldwide dataset of 64 glaciers, the calculated ELAs and measured ELAs were correlated to find the smallest median difference between the measurements. It is recommended that the use of a globally representative AABR value of 1.56 is used for modern applications where a regional AABR value is unknown. This AABR value is also recommended when reconstructing palaeo glacier ELAs. This translates to ~0.42 of uncertainty for palaeotemperature estimation which is well below the uncertainty of other palaeo proxies. Since ELAs are commonly reconstructed to assess palaeoclimatic conditions, I wanted to test the validity of this relationship on modern glaciers. Due to the abundance of modern glaciers in Scandinavia, plus the regional climatic datasets, it was chosen as the study site for parts 2 and 3 of the thesis. I used open-source GLIMS polygons and a GIS toolbox to calculate ELAs for 513 modern glaciers to deduce any shortcomings or misinterpretations of what is known about cirque glaciers and their corresponding climate. For this study, I used the regional AABR value of 1.5. The results indicate that modern ELAs are strongly correlated to distance from the coast, which reflects the present-day precipitation pattern. It indicates that the transition from maritime to continental yields dominant characteristics in the present-day ELA patterns (Winkler et al., 2009). When split into macro-regions, additional strong correlations with latitude, longitude, aspect, summer temperature are evident. The final part of the thesis is a comparison of modern glacier cirques and 3984 geomorphic cirques without glaciers to compare and contrast the relationships with climate. Cirques, the bowl-shaped depressions with steep headwalls are frequently used to obtain palaeoclimatic information for alpine environments. Using cirque floor altitudes (CFAs) as a proxy for palaeo ELAs, the results indicate the topo-climatic factors of latitude, longitude, aspect, and distance from the coast maintain strong relationships with distance from the coast being the most prominent. The gradient inland most likely reflects a similar reduction in precipitation. To conclude, the evidence indicates that CFAs are a useful palaeoproxy for palaeo ELAs with the caveat that the glacial history of Scandinavia has regulated the areas for cirque formation and therefore CFAs.
- Published
- 2021
167. Surficial geological controls on seismic tomography at Mount St. Helens volcano
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Gabrielli, Simona, De Siena, Luca, and Spagnolo, Matteo
- Subjects
Seismic tomography ,Volcanoes - Abstract
Mount St. Helens is a stratovolcano of the Cascade volcanic arc and is one of the most active in the United States. The present morphology is mainly due to the destructive eruption of 18 May 1980, triggered by a five-magnitude earthquake that caused the collapse of a vast sector of the northern part of the volcano. Coda waves are an essential tool to monitor eruption dynamics and model volcanic structures jointly and independantly from velocity anomalies: it is thus fundamental to test their spatial sensitivity to seismic path effects. The thesis reports new research aiming to find a link between seismic imaging of the volcano and its actual geomorphology and surficial geology by qualitative and quantitative approaches. As a first step for coda attenuation imaging, space weighting functions and kernels were used to model the spatial sensitivity of coda waves. While the diffusive approximation is valid for an active seismic dataset to model coda waveforms, it is not valid for the passive seismic dataset of Mount St Helens and, therefore, the multiple scattering was introduce. To measure the relative importance of scattering attenuation vs absorption at Mount St Helens, the Multiple Lapse Time Window Analysis (MLTWA) was applied. The quantities obtained with this technique are the Seismic Albedo B0 (ratio between scattering and total coda attenuation, between 0 and 1) and the Extinction Length (Le, reciprocal of the total attenuation). Results show the typical dominance of scattering attenuation in volcanoes at lower frequencies (3 - 6 Hz), while absorption is the primary attenuation mechanism at 12 Hz and 18 Hz. Still, the seismic albedo is anomalously high (0.95) at 3 Hz. The scattering and absorption parameters derived from MLTWA are used as inputs to construct 2D frequency-dependant bulk sensitivity kernels for the S-wave coda in the multiple-scattering regime (using the Energy Transport Equations - ETE) and to validate the use of analytical diffusive kernels (AD, independant of MLTWA results). At 12 Hz, high coda-attenuation anomalies characterise the eastern side of the volcano using both kernels, in spatial correlation with low-velocity anomalies from literature, generally associated with the deep plumbing system of the volcano. The hypotheses underlying both MLTWA and sensitivity kernels are tested with radiative-transfer forward model of farand near-field envelopes in a half space using RADIATIVE3D. Here, a layered model was implemented with a shallower layer with increased scattering properties to model late coda envelopes. While the broadening of late coda phases improves, this model cannot explain the phases of the intermediate coda with higher amplitude than the direct waves. This behaviour is due to strong near-receiver scattering, which enhance anomalous phases in the intermediate and late coda across the 1980 debris avalanche and central crater. Only at frequencies higher than 3 Hz and in the far-field, diffusion onsets at late lapse times. At 3 Hz, the anomalous albedo, the forward modelling and the results of the tomographic imaging confirm that shallow heterogeneity beneath the extended 1980 debris-avalanche and crater enhance anomalous intermediate and late coda phases, mapping shallow geological contrasts. To better investigate the morphologies biasing the seismic wave path, a geomorphological map was necessary. Literature review pointed out the lack of this information for Mount St. Helens. So, a new geomorphology and surficial geology map has been created, based on a LiDAR acquired in 2003 with 3 m resolution. The effect of the 1980's blast on the entire area is evident, mostly on the northern sector of the volcano, which is covered by the debris avalanche and pyroclastic flow deposits. The volcano completely lost its typical conic shape, in favour of a horseshoe-shape crater rim, with an open side on the NS direction. The map is accompanied by a second one focusing on the geomorphological changes caused by the 2004 eruption, based on a LiDAR of 2009 (1 m resolution). Here, the main morphological variations affect the shape of the main glacier and the dome, both grown in the crater. A qualitative comparison between coda-attenuation imaging and the landforms of Mount St Helens has been done, using the first-ever geomorphological map of the volcano. The map highlighted extremely rough landforms (hummocky structures) in the complex debris avalanche deposit. The comparison with the tomography reveals several matches, not only with the debris avalanche itself but also with other areas of the south-western flank of Mount St Helens, like the Butte Camp dome, where a contrast in attenuation is possibly defining a fracture or a fault connected to this intrusive body. To better understand the influence of key morphologies, forward modelling of the seismic waveforms was fundamental. Starting from the velocity fluctuations obtained from the radiative transfer model, an forward model of the wave equation was introduced. The anisotropic model, following the qualitative observation, shows how the geomorphology is controlling the travel times of SH waves, in particular in two directions: WNW-ESE, following the trend of a buried fault along the South Fork Toutle Valley, and NS, consistent with the main morphological difference between south (mostly untouched by the 1980 eruption) and north (collapsed in 1980) of the volcano. A first analysis of the waveforms of a shallow event of 2005 recorded by three-components array shows a loss in high frequency content for the stations located on the debris avalanche of 1980, unlike other stations laying on older volcanic products. The isotropic model is well reproducing the arrival of the horizontal polarised S waves (SH) at higher frequencies (10 Hz), but not at lower ones (1 Hz and 6 Hz). The introduction of an anisotropic model at 1 Hz and 6 Hz is necessary to explain the arrivals for the stations in the north-northwestern side of the volcano.
- Published
- 2020
168. Climate patterns during former periods of mountain glaciation in Britain and Ireland: Inferences from the cirque record.
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Barr, Iestyn D., Ely, Jeremy C., Spagnolo, Matteo, Clark, Chris D., Evans, Ian S., Pellicer, Xavier M., Pellitero, Ramón, and Rea, Brice R.
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GLACIATION , *MOUNTAINS , *ATMOSPHERIC temperature , *METEOROLOGICAL precipitation , *GEOLOGICAL mapping - Abstract
We map glacial cirques, and analyse spatial variability in their altitude and aspect to derive a long-term, time-integrated, perspective on climate patterns during former periods of mountain glaciation (likely spanning multiple Quaternary glaciations) in Britain and Ireland. The data reveal that, although air temperatures were important, exposure to moisture-bearing air masses was the key factor in regulating sites of former mountain glacier formation, and indicate that during such periods, moisture supply was largely controlled by North Atlantic westerlies, with notable inland precipitation gradients (precipitation decreasing inland), similar to present day. In places, trends in cirque altitude may also reflect regional differences in the extent of cirque deepening, controlled by the dimensions and dynamics of the glaciers that came to occupy them. Specifically, comparatively deep cirques in coastal locations may reflect the former presence of dynamic (fed by moisture from the North Atlantic), but comparatively small, glaciers (largely confined to their cirques). By contrast, decreasing cirque depth further inland, may reflect the former presence of larger and/or less dynamic ice masses, occupying comparatively continental climatic conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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- View/download PDF
169. GlaRe, a GIS tool to reconstruct the 3D surface of palaeoglaciers.
- Author
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Pellitero, Ramón, Rea, Brice R., Spagnolo, Matteo, Bakke, Jostein, Ivy-Ochs, Susan, Frew, Craig R., Hughes, Philip, Ribolini, Adriano, Lukas, Sven, and Renssen, Hans
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GEOGRAPHIC information systems , *GLACIERS , *INTERPOLATION , *ROBUST control , *GLACIAL landforms , *MORAINES , *TOPOGRAPHY - Abstract
Glacier reconstructions are widely used in palaeoclimatic studies and this paper presents a new semi-automated method for generating glacier reconstructions: GlaRe, is a toolbox coded in Python and operating in ArcGIS. This toolbox provides tools to generate the ice thickness from the bed topography along a palaeoglacier flowline applying the standard flow law for ice, and generates the 3D surface of the palaeoglacier using multiple interpolation methods. The toolbox performance has been evaluated using two extant glaciers, an icefield and a cirque/valley glacier from which the subglacial topography is known, using the basic reconstruction routine in GlaRe. Results in terms of ice surface, ice extent and equilibrium line altitude show excellent agreement that confirms the robustness of this procedure in the reconstruction of palaeoglaciers from glacial landforms such as frontal moraines. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
170. Multitemporal glacier inventory revealing four decades of glacier changes in the Ladakh region.
- Author
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Soheb, Mohd, Ramanathan, Alagappan, Bhardwaj, Anshuman, Coleman, Millie, Rea, Brice R., Spagnolo, Matteo, Singh, Shaktiman, and Sam, Lydia
- Subjects
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GLACIERS , *ALPINE glaciers , *WATERSHEDS , *WATER supply , *INVENTORIES , *DATA recorders & recording ,PANGAEA (Supercontinent) - Abstract
Multi-temporal inventories of glacierised regions provide an improved understanding of water resource availability. In this study, we present a Landsat-based multi-temporal inventory of glaciers in four Upper Indus sub-basins and three internal drainage basins in the Ladakh region for the years 1977, 1994, 2009 and 2019. The study records data on 2257 glaciers (of individual size >0.5 km 2) covering an area of ∼7923±106 km 2 which is equivalent to ∼30 % of the total glacier population and ∼89 % of the total glacierised area of the region. Glacier area ranged between 0.5±0.02 and 862±16 km 2 , while glacier length ranged between 0.4±0.02 and 73±0.54 km. Shayok Basin has the largest glacierised area and glacier population, while Tsokar has the least. Results show that the highest concentration of glaciers is found in the higher elevation zones, between 5000 and 6000 m a.s.l., with most of the glaciers facing towards the NW–NE quadrant. The error assessment shows that the uncertainty, based on the buffer-based approach, ranges between 2.6 % and 5.1 % for glacier area, and 1.5 % and 2.6 % for glacier length with a mean uncertainty of 3.2 % and 1.8 %, respectively. This multitemporal inventory is in good agreement with previous studies undertaken in parts of the Ladakh region. The new glacier database for the Ladakh region will be valuable for policy-making bodies, and future glaciological and hydrological studies. The data can be viewed and downloaded from PANGAEA, 10.1594/PANGAEA.940994 (Soheb et al., 2022). [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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171. Do subglacial bedforms comprise a size and shape continuum?
- Author
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Ely, Jeremy C., Clark, Chris D., Spagnolo, Matteo, Stokes, Chris R., Greenwood, Sarah L., Hughes, Anna L.C., Dunlop, Paul, and Hess, Dale
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MARINE ecology , *DRUMLINS , *FLUVIAL geomorphology , *BIG data , *MORAINES - Abstract
Understanding the evolution of the ice-bed interface is fundamentally important for gaining insight into the dynamics of ice masses and how subglacial landforms are created. However, the formation of the suite of landforms generated at this boundary — subglacial bedforms — is a contentious issue that is yet to be fully resolved. Bedforms formed in aeolian, fluvial, and marine environments either belong to separate morphological populations or are thought to represent a continuum of forms generated by the same governing processes. For subglacial bedforms, a size and shape continuum has been hypothesised, yet it has not been fully tested. Here we analyse the largest data set of subglacial bedform size and shape measurements ever collated (96,900 bedforms). Our results show that flutes form a distinct population of narrow bedforms. However, no clear distinction was found between drumlins and megascale glacial lineations (MSGLs), which form a continuum of subglacial lineations. A continuum of subglacial ribs also exists, with no clear size or shape distinctions indicating separate populations. Furthermore, an underreported class of bedform with no clear orientation to ice flow (quasi-circular bedforms) overlaps with the ribbed and lineation continua and typically occurs in spatial transition zones between the two, potentially merging these three bedform types into a larger continuum. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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172. A GIS tool for automatic calculation of glacier equilibrium-line altitudes.
- Author
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Pellitero, Ramón, Rea, Brice R., Spagnolo, Matteo, Bakke, Jostein, Hughes, Philip, Ivy-Ochs, Susan, Lukas, Sven, and Ribolini, Adriano
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GLACIERS , *GEOGRAPHIC information systems , *ALTITUDES , *PYTHONS , *AUTOMATION , *GEOLOGICAL research - Abstract
A toolbox for the automated calculation of glacier equilibrium-line altitudes (ELAs) using the Accumulation Area Ratio, Area-Altitude Balance Ratio, Area-Altitude and Kurowski methods is presented. These are the most commonly-used methods of ELA calculation in palaeo-glacier reconstructions. The toolbox has been coded in Python and runs in ArcGIS requiring only the reconstructed surface of the palaeo-glacier (a DEM) as input. Through fast and automatic calculation this toolbox simplifies the process of ELA determination and can successfully work both for a single glacier and for large datasets of multiple glaciers. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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173. Geomorphological signature of topographically controlled ice flow-switching at a glacier margin: Breiðamerkurjökull (Iceland) as a modern analogue for palaeo-ice sheets.
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Lally, Amy, Ruffell, Alastair, Newton, Andrew M.W., Rea, Brice R., Spagnolo, Matteo, Storrar, Robert D., Kahlert, Thorsten, and Graham, Conor
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MELTWATER , *SUBGLACIAL lakes , *ICE sheets , *ICE streams , *GLACIERS , *FLOW velocity , *SPILLWAYS , *TOPOGRAPHY - Abstract
Ice low-switching, which can involve changes in ice flow velocity and direction, is crucial to a full understanding of ice masses and their response to climate change. A topographically controlled ice flow switch near a glacier margin was recently documented at Breiðamerkurjökull, southeast Iceland, where the central flow unit migrated eastward in response to variations in subglacial topography and the influence of Jökulsárlón glacial lagoon. This site provides an opportunity to study the geomorphic response to ice-margin reconfiguration. Investigating contemporary processes can offer valuable insights into analogous landforms created during the deglaciation of palaeo-ice sheets. The landform assemblage and topographic setting of our Icelandic study site is compared to a palaeo-example from Alberta, Canada, which was once covered by the Laurentide ice sheet. Uncrewed aerial vehicle-(UAV) derived data was used to assess the geomorphic response to this switching and related processes across a 1.5 km2 area of the central flow unit which deglaciated between 2010 and 2023. From 2010 to 2017, the landscape featured streamlined subglacial material, a stable subglacial esker system and proglacial lakes (Landsystem A), shifting to a spillway-dominated system between 2018 and 2023 (Landsystem B). Since 2018 this section of Breiðamerkurjökull has been retreating across a reverse slope bed, resulting in the formation of quasi-annual ice-marginal spillways. Meltwater impoundment at the ice margin, formed ice-contact lakes which eventually initiated ice-margin parallel spillways draining proglacial meltwater along the local land-surface gradient, towards Jökulsárlón. As the ice retreats, an ice-contact lake forms again at the new margin and initiates the erosion of the next ice-marginal spillway. The geomorphological signature demonstrates how subglacial topography and ice-flow switching can significantly influence ice and meltwater dynamics. Since the glacier flow-switch, part of the central unit is now lake-terminating with areas of the margin evolving into a stagnant system, as it is now cut off from the accumulation centre. Therefore, Landsystem B could be analogous to regions of ice stream shut down and where ice masses retreated across reverse slope beds. For example, the Pakowki Lake region of Southeastern Alberta displays a similar landform assemblage and is presented as a palaeo-example in this work. Such insights are important for assessing the efficacy of numerical models in reconstructing the finer scale dynamics of past ice sheets during retreat. • Landform mapping at Breiðamerkurjökull (Iceland) from UAV-derived data reveals two distinct landform assemblages. • Landsystem A (2010-2017): flat subglacial bed, subglacial eskers and proglacial lakes. • Landsystem B (2018-2023): reverse slope bed and ice-marginal spillways. • Landsystem B is analogous to SE Alberta, providing support for existing spillway reconstructions in the region. • The geomorphic response highlights the significance of subglacial topography on ice and meltwater dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
174. Controls on the altitude of Scandinavian cirques: What do they tell us about palaeoclimate?
- Author
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Oien, RachelP., Barr, Iestyn D., Spagnolo, Matteo, Bingham, Robert G., Rea, Brice R., and Jansen, John
- Subjects
- *
ALTITUDES , *SCANDINAVIANS , *TOPOGRAPHY , *TEST validity , *PENINSULAS , *GLACIERS - Abstract
Cirques are glacially eroded, bowl-shaped depressions, characterised by steep headwalls and flat or overdeepened floors. Given their association with past glaciers, cirques are sometimes used as proxies for palaeoclimate. However, cirques are shaped over multiple glacial cycles, and their usefulness as palaeoclimate indicators therefore remains open to question. In this paper, we map 3984 glacier-free cirques across the Scandinavian Peninsula and analyse variations in cirque floor altitude (CFA). We explore the relationships between CFAs and cirque aspect, latitude, longitude, and distance to the coast. We test the validity of using CFAs as indicators of palaeoclimate through comparison with the equilibrium-line altitudes (ELAs) of 513 modern cirque glaciers. Results indicate that both CFAs and modern cirque-glacier ELAs decrease with latitude and vary with aspect, being generally lowest on east-facing slopes. However, the clearest and strongest trend in both CFAs and modern cirque glacier ELAs is an increase in elevation with distance from the modern coast (i.e., distance 'inland'). This likely indicates that similar climatic gradients, particularly an inland reduction in precipitation, acted to regulate former sites of glacier initiation (reflected by CFAs) and modern glacier ELAs. This would imply that CFAs are a useful proxy for palaeoclimate. However, we note that both CFAs and modern ELAs reflect the general topography of this region (with increasing elevations moving inland), and the glacial history of the area (indirectly linked to palaeoclimate) may have played a role in regulating where cirques have formed. For these reasons, we suggest that palaeoclimatic interpretations derived from CFAs should be treated with caution. • We analyse cirque floor altitudes as a proxy for palaeo ELAs across the Scandinavian Peninsula. • Results indicate that precipitation and temperature play a key role in regulating past and present ELAs. • The dominant trend in cirque floor altitudes shows increasing values with distance inland from the coast. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
175. Responses of small mountain glaciers in the Maritime Alps (south-western European Alps) to climatic changes during the Last Glacial Maximum.
- Author
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Rettig, Lukas, Kamleitner, Sarah, Mozzi, Paolo, Ribolini, Adriano, Ivy-Ochs, Susan, Rea, Brice R., Monegato, Giovanni, Christl, Marcus, and Spagnolo, Matteo
- Subjects
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ALPINE glaciers , *LAST Glacial Maximum , *CLIMATE change , *GEOGRAPHIC information systems , *SOLAR radiation , *GLACIERS - Abstract
We present new chronological data and Equilibrium Line Altitude (ELA) information for palaeoglaciers in the Maritime Alps during the Last Glacial Maximum (LGM) and the early deglaciation. Three relatively small catchments were investigated to test if the response of small (1–10 km2) glaciers to LGM climatic forcing was distinguishable from that of larger glacial systems. Palaeoglacier geometries and ELAs were reconstructed using geomorphological evidence and toolboxes in a geographic information system. Chronological control was provided through 10Be surface exposure dating of erratic boulders located on frontal and lateral moraine ridges. Our data indicate two phases of glacier advance or stabilisation in the Maritime Alps, the first occurring at ca. 25 to 24 ka and the second at ca. 20.5 to 19 ka. This is consistent with ages that have been reported from larger outlet lobes along the south-western Alpine fringe, where the second LGM advance is usually preserved in the form of a recessional moraine. Within the uncertainty of the dating technique, there are no distinguishable differences between the responses of small and large Alpine glaciers to the LGM climate. The reconstructed ELAs for palaeoglaciers in the Maritime Alps indicate a considerable variability, which appears to be linked to differences in received solar radiation, from ca. 1600 m a.s.l. for north-facing cirque glaciers to almost 2000 m a.s.l. for glaciers with a southerly aspect. We argue that such influence of solar radiation needs to be considered when using ELAs for palaeoclimatic inferences at regional scales. The calculated ELAs are up to 450 m higher than those in the northern Apennines or the Corsican mountains, indicating a relatively dry LGM climate on the Italian side of the Maritime Alps. • Glaciers in the Maritime Alps advanced at 25 to 24 ka and at 20.5 to 19 ka. • Synchronous advances of small and large glaciers across the south-western Alps. • Catchment aspect and solar radiation had a crucial influence on palaeoglacier ELAs. • Regional glacier ELA of 1800 m a.s.l. indicates a relatively dry LGM climate. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
176. A conceptual model for glaciogenic reservoirs: From landsystems to reservoir architecture.
- Author
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Kurjanski, Bartosz, Rea, Brice R., Spagnolo, Matteo, Cornwell, David G., Howell, John, and Archer, Stuart
- Subjects
- *
CONCEPTUAL models , *RESERVOIRS , *ARCHITECTURE , *ICE sheets , *GLACIAL landforms , *ECONOMIC forecasting , *GEOMORPHOLOGY - Abstract
Glaciogenic sediments are present in many hydrocarbon-producing basins across the globe but their complex nature makes it difficult to characterise the reservoir-quality sedimentary units. Despite this, Ordovician glacial deposits in North Africa, and Carboniferous-Permian glaciogenic sequences in the Middle East, have been proven to host significant, economical, hydrocarbon accumulations. Additionally, discoveries have been made in the shallow (<1000 m below seabed), glacial, Pleistocene sedimentary succession of the North Sea (e.g. Peon and Aviat). This paper provides a predictive exploration framework in the form of a conceptual model of glaciogenic sediment-landform distributions. The model is based on the extensive onshore glacial sedimentary record integrated with available offshore data. It synthesises the published knowledge, drawing heavily on glacial landsystem models, glacial geomorphology and sedimentology of glaciogenic deposits to provide a novel conceptual model allowing for the efficient description and interpretation of glacial sediments and landforms in the subsurface. Subsequently, land-terminating and water-terminating ice sheet depositional systems are described and discussed, with respect to ice advance and retreat cycles. This detailed description focuses on the macro-scale stratigraphic organisation of glacial sediments with relation to the ice margin, aiding the prediction of glaciogenic sediment distributions, and their likely geometry, architecture and connectivity as reservoirs. • A novel conceptual model for the distribution of glaciogenic reservoirs. • First-pass interpretation tool for complex glaciogenic sequences. • Ice margin position controlling reservoir quality. • Identification of landforms and sediments crucial to reservoir predictability. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
177. Deltaic sedimentary environments in the Niger Delta, Nigeria.
- Author
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George, Chinotu Franklin, Macdonald, David I.M., and Spagnolo, Matteo
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- *
GEOMORPHOLOGY , *LANDFORMS , *DELTAS , *ECOLOGY , *RESERVOIRS , *BEACHES , *PLAINS - Abstract
This study is focused on the geomorphology of surface sedimentary environments contained in the fluvial, tidal and wave-dominated areas of the Niger Delta. GIS techniques applied to high-quality Landsat and SPOT images were used to identify and map landforms and processes, as well as quantitatively characterise their metrics and spatial distribution. A detailed analysis shows that the extent of the Niger Delta is 70,000 km2, contrary to previous publications that reported 75,000 km2. The delta has also been remapped and classified into mega sedimentary environments: the upper deltaic plain is 69% of the total extent, while the lower deltaic plain and delta front are 25% and 6% respectively. Other subunits were distinguished and mapped within the upper deltaic plain such as fluvial channels, point bars, braid bars, oxbow lakes, and other lakes. Tidal channels, beaches and spits were identified in the lower deltaic plain and delta front. The geometries of these sedimentary bodies (landforms) appear to be relatively scale-invariant, thus meaning that from the measurement of some dimensional parameters (e.g. the length) it is possible to estimate all others (e.g. the width and overall extent). This is an aspect of great relevance in subsurface analyses where it is often difficult to predict the extent of sedimentary bodies. The correlation between channel width and length (r2 = 0.9), is the strongest relationship found between sedimentary body metrics. • This work presents the geomorphology of Niger Delta surface sedimentary environments. • GIS is applied to map landforms and quantify their metrics and spatial distribution. • Niger Delta is classified as tide-dominated, wave-influenced and fluvial-effect-Tw f. • Present-day Niger Delta geomorphology is relevant to subsurface reservoir studies. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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- View/download PDF
178. Uncertainty in geomorphological responses to climate change.
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Harrison, Stephan, Mighall, Tim, Stainforth, David A., Allen, Philip, Macklin, Mark, Anderson, Edward, Knight, Jasper, Mauquoy, Dmitri, Passmore, David, Rea, Brice, Spagnolo, Matteo, and Shannon, Sarah
- Subjects
- *
CLIMATE change , *ATMOSPHERIC models , *CLIMATE change forecasts , *UNCERTAINTY - Abstract
Successful adaptation to climate change at regional scales can often depend on understanding the nature of geomorphological responses to climate change at those scales. Here we use evidence from landscapes which are known to be environmentally sensitive to show that geomorphological change in response to shifts in climate can be highly nonlinear. Our study sites are two mountain massifs on the western coast of Ireland. Both sites have similar geological and Pleistocene glacial histories and are similar topographically, geomorphologically and in their climate histories. We show that despite these similarities their response to late Holocene, climate change has differed. Both massifs have responded to short-term climate changes over the last 4500 years that are considered to have been uniform across the region, but these climate changes have resulted in highly differentiated and nonlinear landscape responses. We argue this reflects nonlinearity in the forcing–response processes at such scales and suggests that current approaches to modelling the response of such systems to future climate change using numerical climate models may not accurately capture the landscape response. We end by discussing some of the implications for obtaining decision-relevant predictions of landscape responses to climatic forcing and for climate change adaptation and planning, using regional climate models. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
179. Volcanic impacts on modern glaciers: A global synthesis.
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Barr, Iestyn D., Lynch, Colleen M., Mullan, Donal, De Siena, Luca, and Spagnolo, Matteo
- Subjects
- *
GLACIERS , *VOLCANOES , *VOLCANIC activity prediction , *ICE , *FORECASTING - Abstract
Volcanic activity can have a notable impact on glacier behaviour (dimensions and dynamics). This is evident from the palaeo-record, but is often difficult to observe for modern glaciers. However, documenting and, if possible, quantifying volcanic impacts on modern glaciers is important if we are to predict their future behaviour (including crucial ice masses such as the West Antarctic Ice Sheet) and to monitor and mitigate glacio-volcanic hazards such as floods (including jökulhlaups) and lahars. This review provides an assessment of volcanic impacts on the behaviour of modern glaciers (since AD 1800) by presenting and summarising a global dataset of documented examples. The study reveals that shorter-term (days-to-months) impacts are typically destructive, while longer-term (years-to-decades) are more likely protective (e.g., limiting climatically driven ice loss). However, because these events are difficult to observe, particularly before the widespread availability of global satellite data, their frequency and importance are likely underestimated. The study also highlights that because the frequency and nature of volcano-glacier interactions may change with time (e.g., glacier retreat may lead to an increase in explosive volcanic activity), predicting their future importance is difficult. Fortunately, over coming years, continued improvements in remotely sensed data will increase the frequency, and enhance the quality, of observations of volcanic impacts on glaciers, allowing an improved understanding of their past and future operation. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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180. Geomorphological investigation of multiphase glacitectonic composite ridge systems in Svalbard.
- Author
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Lovell, Harold, Benn, Douglas I., Lukas, Sven, Spagnolo, Matteo, Cook, Simon J., Swift, Darrel A., Clark, Chris D., Yde, Jacob C., and Watts, Tom
- Subjects
- *
GEOMORPHOLOGY , *MULTIPHASE flow , *SEDIMENTS , *GEOLOGICAL mapping - Abstract
Some surge-type glaciers on the High-Arctic archipelago of Svalbard have large glacitectonic composite ridge systems at their terrestrial margins. These have formed by rapid glacier advance into proglacial sediments during the active surge phase, creating multicrested moraine complexes. Such complexes can be formed during single surge advances or multiple surges to successively less-extensive positions. The few existing studies of composite ridge systems have largely relied on detailed information on internal structure and sedimentology to reconstruct their formation and links to surge processes. However, natural exposures of internal structure are commonly unavailable, and the creation of artificial exposures is often problematic in fragile Arctic environments. To compensate for these issues, we investigate the potential for reconstructing composite ridge system formation based on geomorphological evidence alone, focusing on clear morphostratigraphic relationships between ridges within the moraine complex and relict meltwater channels/outwash fans. Based on mapping at the margins of Finsterwalderbreen (in Van Keulenfjorden) and Grønfjordbreen (in Grønfjorden), we show that relict meltwater channels that breach outer parts of the composite ridge systems are in most cases truncated upstream within the ridge complex by an inner pushed ridge or ridges at their ice-proximal extents. Our interpretation of this relationship is that the entire composite ridge system is unlikely to have formed during the same glacier advance but is instead the product of multiple advances to successively less-extensive positions, whereby younger ridges are emplaced on the ice-proximal side of older ridges. This indicates that the Finsterwalderbreen composite ridge system has been formed by multiple separate advances, consistent with the cyclicity of surges. Being able to identify the frequency and magnitude of former surges is important as it provides insight into the past behaviour of surge-type glaciers and, if absolute dating is possible, allows for the assessment of surge-type glacier response to climate change on decadal to centennial timescales. Although further investigations into the internal structure of these deposits should be sought where possible, our study demonstrates that geomorphology could be an invaluable tool for reconstructing the formation of composite ridge systems. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
181. Glaciations on ophiolite terrain in the North Pindus Mountains, Greece: New geomorphological insights and preliminary 36Cl exposure dating.
- Author
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Leontaritis, Aris D., Pavlopoulos, Kosmas, Marrero, Shasta M., Ribolini, Adriano, Hughes, Philip D., and Spagnolo, Matteo
- Subjects
- *
LAST Glacial Maximum , *GLACIATION , *GLACIAL landforms , *GEOLOGICAL time scales , *MORAINES , *OPHIOLITES - Abstract
A glacial geomorphological analysis of three valleys on Mt. Mavrovouni (North Pindus Mountains, Greece) is presented alongside a pilot study using cosmogenic 36Cl to obtain surface exposure ages from iron-rich ophiolite glacial and periglacial boulders. At least three distinct morphostratigraphic units of glacial (moraines) and periglacial (relict pronival ramparts) origin have been identified. Four 36Cl surface exposure ages were obtained from the stratigraphically youngest glacial and periglacial deposits. Although this limited dataset with relatively large uncertainties cannot support a robust geochronology, the ages are consistent with the 36Cl-based chronologies of limestone-derived moraines on Mt. Tymphi (NW Greece) and Mt. Chelmos (S Greece), confirming that the last glaciers on this massif formed during the Last Glacial Maximum as also indicated by other studies in the Pindus mountains. At the same time it provides confidence in the suitability of 36Cl dating for iron-rich samples, such as ophiolites, using an updated 36Cl model that incorporates improved production rates for iron spallation. The presented preliminary chronology of moraines and pronival ramparts is based on those ages as well as on local and regional morphostratigraphic correlations. The stabilisation of the most extensive Late Pleistocene glaciers took place during the Last Glacial Maximum, at 27.0 ± 6.5 ka whereas the presence of pronival ramparts dated at 20.2 ± 4.8 ka suggests persisting cold and arid conditions. Older, still undated glacial deposits exist lower in the valleys which can be attributed to the Middle Pleistocene major glaciation phases (MIS 12/MIS 6), based on their relative morphostratigraphic position within the glacial sedimentary sequence. • Benefits of ophiolite for dating glacial landforms compared with limestone • Pilot study of 36Cl surface exposure dating on ophiolites with high iron content • Preliminary glacial chronology using 36Cl ages and morphostratigraphic correlations • Two distinct glaciations ascribed to the Late and Middle Pleistocene respectively. • Last glaciation on Mt. Mavrovouni in NW Greece occurred around the global LGM. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
182. Rapid Sediment Re-Deposition May Limit Carbon Release during Catastrophic Thermokarst Lake Drainage.
- Author
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Burnham, Brian S., Flaig, Peter P., Rea, Brice R., Spagnolo, Matteo, and Young, Michael H.
- Subjects
- *
THERMOKARST , *DRAINAGE , *LAKES , *CARBON in soils , *ATMOSPHERIC sciences , *LAND degradation - Published
- 2022
183. Deep-water sedimentation processes on a glaciated margin: The Foula Wedge trough mouth fan, West of Shetland.
- Author
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Caruso, Simona, Maselli, Vittorio, Rea, Brice, and Spagnolo, Matteo
- Subjects
- *
MELTWATER , *DEBRIS avalanches , *SEDIMENTATION & deposition , *CONTINENTAL margins , *WATER depth , *WEDGES , *GEOMORPHOLOGY , *STRUCTURAL geology - Abstract
Trough Mouth Fans (TMF) are sedimentary depocenters located at glaciated continental margins and consist predominantly of glacigenic debris flow deposits. The Foula wedge is a Pleistocene TMF accumulated offshore West of Shetland over the Northeast Atlantic margin. This study presents an analysis of a 3D seismic reflection dataset imaging the distal Foula wedge basin fan deposits between 1010 and 1100 m water depth, directly downslope from a gully system which was active untill the end of the last deglaciation. Results reveal, in unprecedented detail, the basal surface of this fan system and its internal complex architecture. Features typical of both debris flow deposits and turbidites are identified, including a basin channel network with linear and diverging erosional features forming distinctive terminal lobes, stacked and backstepping. The study links the seafloor morphology of the basin fan with its subsurface geomorphology, showing connection with the downslope gully system to the east. It presents evidence for a complex distal depositional system on glaciated margins, characterised by heterogeneous sediment delivery processes and deposits. A conceptual evolution model is proposed, with a glacigenic debris flow-dominated TMF at the LGM, subsequently influenced by meltwater discharges, with deposition occurring as a function of the shelf margin and slope paleo-morphology, slope substrate composition, interaction of downslope and along slope processes and ice-margin dynamics. • 3D architecture of a glacigenic basin fan system revealed in unprecedented detail. • Subsurface seismic geomorphology highlights a more heterogenous basin depositional system than previously interpreted. • Articulated basin channel network characterised by features typical of both debris flow deposits and turbidites. • Sediment delivery processes controlled by paleo-topography, substrate and meltwater in response to the ice-margin dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
184. The instability theory of drumlin formation and its explanation of their varied composition and internal structure
- Author
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Stokes, Chris R., Fowler, Andrew C., Clark, Chris D., Hindmarsh, Richard C.A., and Spagnolo, Matteo
- Subjects
- *
DRUMLINS , *GLACIOLOGY , *PROBLEM solving , *STABILITY theory , *MATHEMATICAL models , *SEDIMENTS - Abstract
Abstract: Despite their importance in understanding glaciological processes and constraining large-scale flow patterns in palaeo-glaciology, there is little consensus as to how drumlins are formed. Attempts to solve the ‘drumlin problem’ often fail to address how they are created from an initially flat surface in the absence of obvious cores or obstacles. This is a key strength of the instability theory, which has been described in a suite of physically-based mathematical models and proposes that the coupled flow of ice and till causes spontaneous formation of relief in the till surface. Encouragingly, model predictions of bedform height and length are consistent with observations and, furthermore, the theory has been applied to a range of subglacial bedforms and not just drumlins. However, it has yet to confront the myriad observations relating to the composition and internal structure of drumlins and this could be seen as a major deficiency. This paper is a first attempt to assess whether the instability theory is compatible with the incredible diversity of sediments and structures found within drumlins. We summarise the underlying principles of the theory and then describe and attempt to explain the main types of drumlin composition (e.g. bedrock, till, glaciofluvial sediments, and combinations thereof). Contrary to a view which suggests that the presence of some sedimentary sequences (e.g. horizontally stratified cores) is inconsistent with the theory, we suggest that one would actually expect a diverse range of constituents depending on the inheritance of sediments that pre-date drumlin formation, the duration and variability of ice flow, and the balance between erosion and deposition (till continuity) at the ice–bed interface. We conclude that the instability theory is compatible with (and potentially strengthened by) what is known about drumlin composition and, as such, offers the most complete and promising solution to the drumlin problem to date. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
185. 60 million years of glaciation in the Transantarctic Mountains.
- Author
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Barr ID, Spagnolo M, Rea BR, Bingham RG, Oien RP, Adamson K, Ely JC, Mullan DJ, Pellitero R, and Tomkins MD
- Subjects
- Antarctic Regions, Ice Cover
- Abstract
The Antarctic continent reached its current polar location ~83 Ma and became shrouded by ice sheets ~34 Ma, coincident with dramatic global cooling at the Eocene-Oligocene boundary. However, it is not known whether the first Antarctic glaciers formed immediately prior to this or were present significantly earlier. Here we show that mountain glaciers were likely present in the Transantarctic Mountains during the Late Palaeocene (~60-56 Ma) and middle Eocene (~48-40 Ma). Temperate (warm-based) glaciers were prevalent during the Late Eocene (~40-34 Ma) and, in reduced numbers, during the Oligocene (~34-23 Ma), before larger, likely cold-based, ice masses (including ice sheets) dominated. Some temperate mountain glaciers were present during the Miocene Climatic Optimum (~15 Ma), before a widespread switch to cold-based glaciation. Our findings highlight the longevity of glaciation in Antarctica and suggest that glaciers were present even during the Early-Cenozoic greenhouse world., (© 2022. The Author(s).)
- Published
- 2022
- Full Text
- View/download PDF
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