The document examines the dynamics, extent, and timing of the British Ice Sheet during the Last Glacial Maximum through analysis of glacial landforms and dated sites in northern England. Key findings include:
1) The ice sheet was heterogeneous, reaching its maximum extent at different times in different areas. It advanced slowly from ice fields in upland areas before filling valleys.
2) Dynamics varied throughout growth and retreat. During growth, ice flowed radially from centers; during retreat, regional dispersal centers dominated.
3) Analysis of landforms showed complex and changing flow patterns, with ice reaching its maximum approximately 27,000 years ago before retreating rapidly across waterways by 15,000 years ago.
1) Scientists discovered a massive subsurface ice layer beneath an area of intermittent melt pond formation on the Larsen C Ice Shelf in Antarctica.
2) The ice layer is at least 16 km across, several km long, and tens of meters deep. It consists of two units - an upper solid ice unit formed from refreezing of ponded water, and a lower infiltration ice unit formed from refreezing of meltwater that percolated into dense firn.
3) Analysis of borehole data, firn modeling, and satellite images indicates the ice layer formed in response to intense surface melting and pond formation between 2001-2009, and is likely warmer and denser than ice in areas without such melting
This study presents a comprehensive digital mosaic of ice motion across Antarctica assembled from satellite radar data. The data reveal widespread, patterned, enhanced flow of tributary glaciers reaching hundreds to thousands of kilometers inland over the entire continent. This emphasizes the importance of basal-slip dominated tributary flow over deformation-dominated ice sheet flow, redefining our understanding of ice sheet dynamics. The extensive network of fast-flowing tributaries challenges prior views of ice sheet flow and implies a tighter connection between coastal and interior ice flow than previously thought.
Nuclear Magnetic Ressonance - Water content assessment in glacier ice and ben...Fundació Marcel Chevalier
Glaciers are widely spread on polar and sub-polar regions but also on middle latitude mountains, where cold-dry type glaciers, polythermal glaciers and temperate-wet glaciers are respectively present. Assess their water content is capital to understand the ice dynamics and how is related with the climate change.
Subglacial drainage in porous aquifer and sediment consolidation patterns in the glaciated valley of Andorra (Pyrenees). The poster was presented for the IAG/AIG (International Association of Geomorphologists) Regional Conference on Geomorphology Geodiversity of polar landforms which was held in Longyearbyen (Spitsbergen, Norway) on August 1-5, 2007. Conference was organised on the occasion of the International Polar Year 2007/2008 by the Association of Polish Geomorphologists.
Recent north magnetic pole acceleration towards Siberia caused by flux lobe e...Sérgio Sacani
The wandering of Earth’s north magnetic pole, the location where the magnetic field points vertically downwards, has long been
a topic of scientific fascination. Since the first in situ measurements in 1831 of its location in the Canadian arctic, the pole has
drifted inexorably towards Siberia, accelerating between 1990 and 2005 from its historic speed of 0–15 km yr−1
to its present
speed of 50–60 km yr−1
. In late October 2017 the north magnetic pole crossed the international date line, passing within 390 km
of the geographic pole, and is now moving southwards. Here we show that over the last two decades the position of the north
magnetic pole has been largely determined by two large-scale lobes of negative magnetic flux on the core–mantle boundary
under Canada and Siberia. Localized modelling shows that elongation of the Canadian lobe, probably caused by an alteration
in the pattern of core flow between 1970 and 1999, substantially weakened its signature on Earth’s surface, causing the pole
to accelerate towards Siberia. A range of simple models that capture this process indicate that over the next decade the north
magnetic pole will continue on its current trajectory, travelling a further 390–660 km towards Siberia.
Glaciations in response_to_climate_variations_preconditioned_by_evolving_topo...Sérgio Sacani
This document summarizes a study that used numerical modeling to examine how the topographic distribution (hypsometry) of landscapes influences glacial extent in response to climate variations. The key findings are:
1) In landscapes without prior glaciation, there is a nearly linear relationship between climate and glacial area.
2) In previously glaciated landscapes with hypsometric maxima below the snowline, highly nonlinear and rapid glacial expansions occur with minimal climate forcing when the snowline reaches the hypsometric maximum.
3) Glaciations before 950,000 years ago likely preconditioned landscapes in Europe and North America, producing landforms and hypsometric distributions that led to more extensive
This document summarizes a seismic study of a coal deposit in Wabamun, Alberta. It provides background on the study area and coal deposit geology. It then describes the acquisition and processing of seismic reflection data from two lines over the deposit. The data is analyzed and interpreted, with control from a well. On one line, variations in the seismic character of the coal reflection are correlated to stratigraphic variations within the coal zone as revealed by the well log. Anomalies in the seismic data are interpreted to indicate structural deformation and changes in coal properties. The study demonstrates detailed geological interpretation of high-resolution seismic data over a shallow coal deposit.
TU1.L10.2 - ESTIMATION OF ICE THICKNESS OF TUNDRA LAKES USING ERS–ENVISAT CR...grssieee
This document presents a method for estimating ice thickness in tundra lakes using cross-interferometry of ERS and ENVISAT SAR data. The method is tested on two study sites in Siberia and Canada, showing coherence over frozen lakes allows sensitivity to ice thickness changes of around 3 meters. Comparisons to in-situ measurements confirm the potential to map ice thickness and lake floor topography where the ice is frozen to the bottom. Limitations exist for other ice types where the dominant scattering is not from the ice/water or ice/ground interfaces.
1) Scientists discovered a massive subsurface ice layer beneath an area of intermittent melt pond formation on the Larsen C Ice Shelf in Antarctica.
2) The ice layer is at least 16 km across, several km long, and tens of meters deep. It consists of two units - an upper solid ice unit formed from refreezing of ponded water, and a lower infiltration ice unit formed from refreezing of meltwater that percolated into dense firn.
3) Analysis of borehole data, firn modeling, and satellite images indicates the ice layer formed in response to intense surface melting and pond formation between 2001-2009, and is likely warmer and denser than ice in areas without such melting
This study presents a comprehensive digital mosaic of ice motion across Antarctica assembled from satellite radar data. The data reveal widespread, patterned, enhanced flow of tributary glaciers reaching hundreds to thousands of kilometers inland over the entire continent. This emphasizes the importance of basal-slip dominated tributary flow over deformation-dominated ice sheet flow, redefining our understanding of ice sheet dynamics. The extensive network of fast-flowing tributaries challenges prior views of ice sheet flow and implies a tighter connection between coastal and interior ice flow than previously thought.
Nuclear Magnetic Ressonance - Water content assessment in glacier ice and ben...Fundació Marcel Chevalier
Glaciers are widely spread on polar and sub-polar regions but also on middle latitude mountains, where cold-dry type glaciers, polythermal glaciers and temperate-wet glaciers are respectively present. Assess their water content is capital to understand the ice dynamics and how is related with the climate change.
Subglacial drainage in porous aquifer and sediment consolidation patterns in the glaciated valley of Andorra (Pyrenees). The poster was presented for the IAG/AIG (International Association of Geomorphologists) Regional Conference on Geomorphology Geodiversity of polar landforms which was held in Longyearbyen (Spitsbergen, Norway) on August 1-5, 2007. Conference was organised on the occasion of the International Polar Year 2007/2008 by the Association of Polish Geomorphologists.
Recent north magnetic pole acceleration towards Siberia caused by flux lobe e...Sérgio Sacani
The wandering of Earth’s north magnetic pole, the location where the magnetic field points vertically downwards, has long been
a topic of scientific fascination. Since the first in situ measurements in 1831 of its location in the Canadian arctic, the pole has
drifted inexorably towards Siberia, accelerating between 1990 and 2005 from its historic speed of 0–15 km yr−1
to its present
speed of 50–60 km yr−1
. In late October 2017 the north magnetic pole crossed the international date line, passing within 390 km
of the geographic pole, and is now moving southwards. Here we show that over the last two decades the position of the north
magnetic pole has been largely determined by two large-scale lobes of negative magnetic flux on the core–mantle boundary
under Canada and Siberia. Localized modelling shows that elongation of the Canadian lobe, probably caused by an alteration
in the pattern of core flow between 1970 and 1999, substantially weakened its signature on Earth’s surface, causing the pole
to accelerate towards Siberia. A range of simple models that capture this process indicate that over the next decade the north
magnetic pole will continue on its current trajectory, travelling a further 390–660 km towards Siberia.
Glaciations in response_to_climate_variations_preconditioned_by_evolving_topo...Sérgio Sacani
This document summarizes a study that used numerical modeling to examine how the topographic distribution (hypsometry) of landscapes influences glacial extent in response to climate variations. The key findings are:
1) In landscapes without prior glaciation, there is a nearly linear relationship between climate and glacial area.
2) In previously glaciated landscapes with hypsometric maxima below the snowline, highly nonlinear and rapid glacial expansions occur with minimal climate forcing when the snowline reaches the hypsometric maximum.
3) Glaciations before 950,000 years ago likely preconditioned landscapes in Europe and North America, producing landforms and hypsometric distributions that led to more extensive
This document summarizes a seismic study of a coal deposit in Wabamun, Alberta. It provides background on the study area and coal deposit geology. It then describes the acquisition and processing of seismic reflection data from two lines over the deposit. The data is analyzed and interpreted, with control from a well. On one line, variations in the seismic character of the coal reflection are correlated to stratigraphic variations within the coal zone as revealed by the well log. Anomalies in the seismic data are interpreted to indicate structural deformation and changes in coal properties. The study demonstrates detailed geological interpretation of high-resolution seismic data over a shallow coal deposit.
TU1.L10.2 - ESTIMATION OF ICE THICKNESS OF TUNDRA LAKES USING ERS–ENVISAT CR...grssieee
This document presents a method for estimating ice thickness in tundra lakes using cross-interferometry of ERS and ENVISAT SAR data. The method is tested on two study sites in Siberia and Canada, showing coherence over frozen lakes allows sensitivity to ice thickness changes of around 3 meters. Comparisons to in-situ measurements confirm the potential to map ice thickness and lake floor topography where the ice is frozen to the bottom. Limitations exist for other ice types where the dominant scattering is not from the ice/water or ice/ground interfaces.
Monitoring Changes in Antarctic Sea Ice Phenology: 1990-2015priscillaahn
This study analyzed changes in Antarctic sea ice phenology from 1990-2015 using satellite microwave data. The results show a trend of later melt seasons, with more sea ice persisting longer into the summer. Specifically, there was a 2.2% annual increase in the number of pixels classified as non-seasonal sea ice, indicating longer melt seasons. However, the classification scheme may not fully capture Antarctic sea ice behavior, which melts almost completely each summer due to less confinement than Arctic sea ice. Overall, the analysis found tentative evidence of delayed melt, but uncertainties remain regarding optimal classification of Antarctic sea ice types.
This study used ground-penetrating radar (GPR) to analyze the Quaternary stratigraphy of a sandy portion of the Marambaia Isthmus in Brazil. Five radar facies were identified in one GPR profile, representing different depositional environments: facies A and A' showed planar reflections indicating a low-energy beach or shore environment; facies B showed sigmoidal reflections indicating transport of shelf sediments during a marine transgression; facies C showed oblique reflections indicating eolian dune deposition during lower sea levels; and facies D showed well-sorted sand grains deposited by reworking. Together, the facies suggest periods of marine transgression and lower sea levels with dune formation, providing information on the
2012 BISHOP Interpretation and modelling of the Pedirka Basin using magnetics...Christopher Bishop
The document summarizes the interpretation and modeling of geophysical data in the Pedirka Basin of central Australia to better understand basement geology and estimate depths. Gravity and magnetic data were combined with seismic and well log data. Gravity modeling of a profile suggested a basement depth of ~5.5km. A 3D magnetic inversion voxel clipped to 0.012 SI units placed the top of basement at ~5,550m on the gravity modeled profile, illustrating the heterogeneous basement. The modeling provides new insights into basement depths and composition in the underexplored Pedirka Basin.
Hydrocarbon potential of the Borno Basin through Electrofacies and depositional environment analysis was carried out from well log and seismic reflection data to reassess the potential of the Basin thereby justifying the huge financial commitment of the Government. The reflection configuration pattern from the seismic reflection lines is characterized by variation from parallel, continuous and strong amplitude to sub parallel, chaotic discontinuous and low amplitude which indicate a variation from a low energy basinal setting of uniform rate of continental deposition to high energy environment of monolithologic deposits. Furthermore, the derivable log signatures shows a variation from serrated mud/sand to serrated blocky to serrated funnel and bell shapes with depth. This imply a stable massive mud/sand rich basinwide environment to an upward regressive sequence of bar deposit followed by a deltaic estuarine clastic sediment to gradual upward transgressive decrease in grain size to a fluvial point bar deposit. These environments identified from the research are known to be hydrocarbon province.
This document discusses the climates of simple non-vegetated surfaces including sandy deserts, snow and ice, and water surfaces. It covers the energy and water balances, radiation budgets, and resulting climates of these surfaces. Key points include the low water vapor and high albedo of sandy deserts, the exponential attenuation of solar radiation with depth in snow and ice, high albedos of snow and ice surfaces, heat flux components in the energy balances of snowpacks and water bodies, and characteristics of temperature profiles and heat transfer in these different surfaces.
Dr. Ram Ben-David presented on two mining projects and two geoengineering projects from his portfolio. For the Sakassou gold exploration project in Cote d'Ivoire, he discussed the regional geology, exploration phases including soil and trench sampling, and initial results. For the Shefa Yamim exploration project in Israel, he outlined the exploration licenses, his role as chief geologist developing programs, and some regional geology. He also presented on coastal cliff stability projects in Israel examining geological problems and engineering solutions, and a large underground parking project in Jerusalem where he provided geological supervision of tunneling.
This document provides a summary of a gravity survey conducted over the Kibby Basin property in Nevada from June 13-19, 2016. A total of 609 gravity stations were measured on a 500m grid and along roads. The data was processed to produce complete Bouguer anomaly grids using a density of 2.60 g/cc. A basin model was generated by adjusting 9216 prisms to fit the observed residual gravity, with basin fill assigned a density of 2.1 g/cc. The model shows the basin reaches a maximum depth of 4000m. Interpreted structures from the total gradient indicate a north-south elongated pull-apart basin formed by left-lateral strike-slip faults.
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...IOSR Journals
Hydrocarbon reservoir has been delineated and their boundaries mapped using direct indicators from 3-D seismic and well log data from an oil field in Nembe creek, Niger Delta region. Well log signatures were employed to identify hydrocarbon bearing sands. Well to seismic correlation revealed that these reservoirs tied with direct hydrocarbon indicators on the seismic section. The results of the interpreted well logs revealed that the hydrocarbon interval in the area occurs between 6450ft to 6533ft for well A, 6449ft to 6537ft for well B and 6629ft to 6704ft for well C; which were delineated using the resistivity, water saturation and gamma ray logs. Cross plot analysis was carried out to validate the sensitivity of the rock attributes to reservoir saturation condition. Analysis of the extracted seismic attribute slices revealed HD5000 as hydrocarbon bearing reservoir.
In the past decade, particularly since the last summary of the
subject (Calvet, 2004), the Quaternary glaciation of the Pyrenees
has been the focus of new research. Unequal progress
has been achieved on three aspects: mapping the extent of
the Pyrenean ice field, quantifying the geomorphological
impact of glaciation on the preglacial landscape and refining
the chronology of the glacial fluctuations.
High Resolution Seismic Reflections: Coal Mine FieldsAli Osman Öncel
- High-resolution seismic reflection data was collected near Harco, Illinois to map shallow coal seams and help predict areas of roof instability, low sulfur coal, and geologic disturbances prior to mining.
- The data helped locate several faults, channels, and facies changes affecting the Herrin (No. 6) and Springfield (No. 5) coal seams, which drill hole data alone could not adequately map, even with boreholes spaced 25 meters apart.
- Processing and interpretation of the seismic data, combined with drill hole information, was useful for safe and economical exploitation of the coal deposits by mapping the coal seams and detecting features that could impact mining operations.
Simulated versus Satellite Retrieval Distribution Patterns of the Snow Water ...Agriculture Journal IJOEAR
Abstract— Snow is a very important component of the climate system which controls surface energy and water balances. Its high albedo, low thermal conductivity and properties of surface water storage impact regional to global climate. The various properties characterizing snow are highly variable and so have to be determined as dynamically active components of climate. However, on large spatial scales the properties of snow are not easily quantified either from numerical modelling or observations. Since neither observations (ground measurements or satellite retrievals) nor models alone are capable of providing enough adequate information about the time space variability of snow properties, it becomes necessary to combine their information. In the presented study the obtained with the regional climate model RegCM snow water equivalent (SWE) on monthly basis over Southeast Europe for a time window of 14 consecutive winters is compared with the Globsnow satellite product. The concordance between both datasets is evaluated with number of statistical scores. The result reveals the principal agreement between the two products, but however, with very significant discrepancies, mainly overestimations, for some years and gridcells.
This document summarizes a study that used multisensor fusion of altimetry data to monitor changes in ice sheets from 2003 to 2009. The study reconstructed spatial and temporal elevation changes across Greenland by combining satellite laser altimetry from ICESat with airborne laser data. Results showed complex patterns of thickening and thinning, with average rates of 257 km3/yr of ice sheet loss, equivalent to 232 Gt/yr of mass loss.
18494_Guided Facies Modeling using 3D Seismic and WellRoy Cox
This document summarizes research using 3D seismic data and well logs to create more geologically realistic models of reservoir facies distributions. Seismic attribute images were interpreted to map fluvial depositional features like channels. These geomorphic objects were then used to guide facies modeling between wells. This "soft conditioning" approach produced models that better honored both well data and seismic trends compared to previous methods. It was applied to reservoirs in the BB oil field comprised of Miocene fluvial and coastal deposits. Seismic slices helped delineate multiple channel belts and a point bar complex that informed the final facies models.
Qualitative Comparison of Offset Surfaces Between the Central and Eastern Gar...Tom Crane
This study analyzes and compares offset surfaces along the central and eastern segments of the Garlock fault in California using LiDAR data and imagery. Qualitative methods were used to establish relative ages of alluvial surfaces based on characteristics like height, shape, dissection, surface darkness, and smoothness. Measured offsets of surfaces of similar inferred ages along the central fault were greater than for the eastern fault, suggesting a reduction in slip rate eastward. Preliminary slip rate estimates are 4.2 mm/yr for the central fault and 1.0 mm/yr for the eastern fault, indicating a decreasing rate from west to east along the fault. OSL dating of samples will provide firmer slip rate calculations to verify
- The project aimed to understand the failure of a 6-day forecast over Europe in April 2011 by examining convection over North America. The forecast significantly underestimated convection from an MCS over the central US on April 10th.
- Verification showed the forecast error in the OpenIFS model. Examining fields like CAPE and precipitation revealed errors in the location and timing of convection in the forecast.
- A 5-member ensemble was run but none improved on the control forecast, all overestimated blocking over Europe. The ensemble mean performed worse than the control forecast. Perturbations in the initial conditions had little impact on the forecasts.
This study uses basin modelling to analyze the hydrocarbon potential of two Neogene sedimentary sub-basins in southern Hungary. The modelling simulated the subsidence and thermal maturation histories. It determined that the southern sub-basin reached greater depths and temperatures, resulting in gas generation from source rocks beginning 11.6 million years ago. Oil generation in the northern sub-basin began more recently around 6.8 million years ago. While hydrocarbons migrated upward along faults, accumulations have only formed so far in the southern sub-basin within anticline structures in carbonate formations. The complex geological evolution and thermal anomalies revealed by the modelling provide new perspectives for hydrocarbon exploration in the area.
Surface Reflection Seismic Method: Coal Mines FieldAli Osman Öncel
This document summarizes a study that used seismic modeling and analysis of seismic data to interpret the stratigraphy of a shallow coal deposit in central Alberta, Canada. 1D and 2D modeling helped relate seismic reflection character to stratigraphic variations in the coal zone. Seismic lines from the study area were reprocessed and interpreted, finding that reflection character could be quantitatively related to coal zone stratigraphy. The study demonstrated that detailed seismic interpretation is possible by relating reflection seismic data to variations in density logs from wells.
Fault Tectonics of the NE Black Sea Shelf and Its Relevance to Hydrocarbon Po...Şarlatan Avcısı
Abstract
Although faults of the consolidated crust play crucial role in the origin of sedimentary features and hydrocarbon accumulation, the tectonic setting of the NE Black Sea shelf is poorly known. The aim of this work is to compile the most detailed map of faults in the consolidated crust and test comprehensively a linkage between crustal disturbances and potential hydrocarbon features. Understanding such a relationship may be helpful in planning location of exploration boreholes.
For the first time, 3D gravity and magnetic models have been obtained at a scale of 1:200,000 for the NE Black Sea shelf. Based on the analysis of the observed magnetic field and gravity effect of the consolidated crust, the most detailed map has bееn compiled for tectonic faults of the consolidated crust. The relationship has been derived between the crustal and sedimentary faults. The prospective local anticlinal features have been revealed to be associated with certain systems of tectonic disturbances in the different crustal layers and magnetic inhomogeneity in the crust. The magnetic bodies of the consolidated crust and sedimentary cover can be of common origin due to
the influence of hydrocarbons vertically migrating along the deep faults. An individual block of high density has been delimited by the faults in the consolidated crust where there occur practically all prospective hydrocarbon features. The southern margin of this block is recommended as a new potential area for oil and gas exploration where gas seeps
are genetically related to the tectonic disturbances of different orders.
A first model has been derived for thermal evolution of the Kerch-Taman Trough from the pseudo-well method. A total subsidence of its basement can reach 5.0-6.5 km. The present-day temperature vs. depth profiles have been calculated. A thermal and stratigraphic position
has been determined for zones of oil and gas origin.
source : V.I. Starostenko1, B.L. Krupskyi1, I.K. Pashkevich1, O.M. Rusakov1,
I.B. Makarenko1, R.I. Kutas1, V.V Gladun1, O.V. Legostaeva1, T.V. Lebed1, and
P.Ya. Maksymchuk1
Search and Discovery Article #30155 (2011) Posted March 28, 2011
*Adapted from oral presentation at AAPG European Region Annual Conference, Kiev, Ukraine, October 17-19, 2010
1Institute of Geophysics, National Academy of Sciences of Ukraine, National Joint stock-Company Naftogaz of Ukraine, Kyiv, Ukraine
This study examines how the interpretation of drumlins in areas surrounding Lake Simcoe, Ontario changes when using different topographic maps and digital elevation models over time. The researchers analyzed drumlin features in three regions - an urban area on sand plains, a rural clay plain area, and a till plain region - using topographic maps from different years and a DEM. They found that while early topographic maps and the DEM displayed similar detail, drumlins appeared to erode over time, likely due to urbanization and the underlying sediment type. Later topographic maps had less detail than same-resolution DEMs, suggesting topographic maps are not as reliable for drumlin mapping as other digital tools.
Northern larsen ice shelf Antarctica: further retreat after collapseSimoneBoccuccia
This document discusses changes to glaciers and ice shelves in northern Larsen Ice Shelf, Antarctica after the collapse of parts of the ice shelf in 1995. It finds that large glaciers retreated several kilometers inland from their previous grounding lines after losing the back pressure from the ice shelves. Interferometry showed the main glacier in the area, Drygalski Glacier, accelerated its flow speed up to three times over 4 years after ice shelf collapse. Other grounded glaciers also saw accelerations, suggesting ice shelf collapse could contribute to sea level rise. The document also documents further retreat of Larsen B ice shelf through October 2000.
This document provides an outline of a PhD project aiming to assess the shallow geothermal potential of Northern Ireland. The project has three main aims: 1) audit the shallow geothermal resource, 2) grade areas based on their economic heat potential, and 3) progress high-potential options to a business case. The researcher will develop screening criteria for sites and geologically map focus areas to characterize aquifers. Maps of permeable rock units and groundwater data will be used to create a shallow geothermal potential map. Proglacial sediments like deltas, eskers and outwash plains provide the most prospective reservoirs due to their high permeability. The researcher has identified the Malone Sands delta near Belfast and Kil
Monitoring Changes in Antarctic Sea Ice Phenology: 1990-2015priscillaahn
This study analyzed changes in Antarctic sea ice phenology from 1990-2015 using satellite microwave data. The results show a trend of later melt seasons, with more sea ice persisting longer into the summer. Specifically, there was a 2.2% annual increase in the number of pixels classified as non-seasonal sea ice, indicating longer melt seasons. However, the classification scheme may not fully capture Antarctic sea ice behavior, which melts almost completely each summer due to less confinement than Arctic sea ice. Overall, the analysis found tentative evidence of delayed melt, but uncertainties remain regarding optimal classification of Antarctic sea ice types.
This study used ground-penetrating radar (GPR) to analyze the Quaternary stratigraphy of a sandy portion of the Marambaia Isthmus in Brazil. Five radar facies were identified in one GPR profile, representing different depositional environments: facies A and A' showed planar reflections indicating a low-energy beach or shore environment; facies B showed sigmoidal reflections indicating transport of shelf sediments during a marine transgression; facies C showed oblique reflections indicating eolian dune deposition during lower sea levels; and facies D showed well-sorted sand grains deposited by reworking. Together, the facies suggest periods of marine transgression and lower sea levels with dune formation, providing information on the
2012 BISHOP Interpretation and modelling of the Pedirka Basin using magnetics...Christopher Bishop
The document summarizes the interpretation and modeling of geophysical data in the Pedirka Basin of central Australia to better understand basement geology and estimate depths. Gravity and magnetic data were combined with seismic and well log data. Gravity modeling of a profile suggested a basement depth of ~5.5km. A 3D magnetic inversion voxel clipped to 0.012 SI units placed the top of basement at ~5,550m on the gravity modeled profile, illustrating the heterogeneous basement. The modeling provides new insights into basement depths and composition in the underexplored Pedirka Basin.
Hydrocarbon potential of the Borno Basin through Electrofacies and depositional environment analysis was carried out from well log and seismic reflection data to reassess the potential of the Basin thereby justifying the huge financial commitment of the Government. The reflection configuration pattern from the seismic reflection lines is characterized by variation from parallel, continuous and strong amplitude to sub parallel, chaotic discontinuous and low amplitude which indicate a variation from a low energy basinal setting of uniform rate of continental deposition to high energy environment of monolithologic deposits. Furthermore, the derivable log signatures shows a variation from serrated mud/sand to serrated blocky to serrated funnel and bell shapes with depth. This imply a stable massive mud/sand rich basinwide environment to an upward regressive sequence of bar deposit followed by a deltaic estuarine clastic sediment to gradual upward transgressive decrease in grain size to a fluvial point bar deposit. These environments identified from the research are known to be hydrocarbon province.
This document discusses the climates of simple non-vegetated surfaces including sandy deserts, snow and ice, and water surfaces. It covers the energy and water balances, radiation budgets, and resulting climates of these surfaces. Key points include the low water vapor and high albedo of sandy deserts, the exponential attenuation of solar radiation with depth in snow and ice, high albedos of snow and ice surfaces, heat flux components in the energy balances of snowpacks and water bodies, and characteristics of temperature profiles and heat transfer in these different surfaces.
Dr. Ram Ben-David presented on two mining projects and two geoengineering projects from his portfolio. For the Sakassou gold exploration project in Cote d'Ivoire, he discussed the regional geology, exploration phases including soil and trench sampling, and initial results. For the Shefa Yamim exploration project in Israel, he outlined the exploration licenses, his role as chief geologist developing programs, and some regional geology. He also presented on coastal cliff stability projects in Israel examining geological problems and engineering solutions, and a large underground parking project in Jerusalem where he provided geological supervision of tunneling.
This document provides a summary of a gravity survey conducted over the Kibby Basin property in Nevada from June 13-19, 2016. A total of 609 gravity stations were measured on a 500m grid and along roads. The data was processed to produce complete Bouguer anomaly grids using a density of 2.60 g/cc. A basin model was generated by adjusting 9216 prisms to fit the observed residual gravity, with basin fill assigned a density of 2.1 g/cc. The model shows the basin reaches a maximum depth of 4000m. Interpreted structures from the total gradient indicate a north-south elongated pull-apart basin formed by left-lateral strike-slip faults.
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...IOSR Journals
Hydrocarbon reservoir has been delineated and their boundaries mapped using direct indicators from 3-D seismic and well log data from an oil field in Nembe creek, Niger Delta region. Well log signatures were employed to identify hydrocarbon bearing sands. Well to seismic correlation revealed that these reservoirs tied with direct hydrocarbon indicators on the seismic section. The results of the interpreted well logs revealed that the hydrocarbon interval in the area occurs between 6450ft to 6533ft for well A, 6449ft to 6537ft for well B and 6629ft to 6704ft for well C; which were delineated using the resistivity, water saturation and gamma ray logs. Cross plot analysis was carried out to validate the sensitivity of the rock attributes to reservoir saturation condition. Analysis of the extracted seismic attribute slices revealed HD5000 as hydrocarbon bearing reservoir.
In the past decade, particularly since the last summary of the
subject (Calvet, 2004), the Quaternary glaciation of the Pyrenees
has been the focus of new research. Unequal progress
has been achieved on three aspects: mapping the extent of
the Pyrenean ice field, quantifying the geomorphological
impact of glaciation on the preglacial landscape and refining
the chronology of the glacial fluctuations.
High Resolution Seismic Reflections: Coal Mine FieldsAli Osman Öncel
- High-resolution seismic reflection data was collected near Harco, Illinois to map shallow coal seams and help predict areas of roof instability, low sulfur coal, and geologic disturbances prior to mining.
- The data helped locate several faults, channels, and facies changes affecting the Herrin (No. 6) and Springfield (No. 5) coal seams, which drill hole data alone could not adequately map, even with boreholes spaced 25 meters apart.
- Processing and interpretation of the seismic data, combined with drill hole information, was useful for safe and economical exploitation of the coal deposits by mapping the coal seams and detecting features that could impact mining operations.
Simulated versus Satellite Retrieval Distribution Patterns of the Snow Water ...Agriculture Journal IJOEAR
Abstract— Snow is a very important component of the climate system which controls surface energy and water balances. Its high albedo, low thermal conductivity and properties of surface water storage impact regional to global climate. The various properties characterizing snow are highly variable and so have to be determined as dynamically active components of climate. However, on large spatial scales the properties of snow are not easily quantified either from numerical modelling or observations. Since neither observations (ground measurements or satellite retrievals) nor models alone are capable of providing enough adequate information about the time space variability of snow properties, it becomes necessary to combine their information. In the presented study the obtained with the regional climate model RegCM snow water equivalent (SWE) on monthly basis over Southeast Europe for a time window of 14 consecutive winters is compared with the Globsnow satellite product. The concordance between both datasets is evaluated with number of statistical scores. The result reveals the principal agreement between the two products, but however, with very significant discrepancies, mainly overestimations, for some years and gridcells.
This document summarizes a study that used multisensor fusion of altimetry data to monitor changes in ice sheets from 2003 to 2009. The study reconstructed spatial and temporal elevation changes across Greenland by combining satellite laser altimetry from ICESat with airborne laser data. Results showed complex patterns of thickening and thinning, with average rates of 257 km3/yr of ice sheet loss, equivalent to 232 Gt/yr of mass loss.
18494_Guided Facies Modeling using 3D Seismic and WellRoy Cox
This document summarizes research using 3D seismic data and well logs to create more geologically realistic models of reservoir facies distributions. Seismic attribute images were interpreted to map fluvial depositional features like channels. These geomorphic objects were then used to guide facies modeling between wells. This "soft conditioning" approach produced models that better honored both well data and seismic trends compared to previous methods. It was applied to reservoirs in the BB oil field comprised of Miocene fluvial and coastal deposits. Seismic slices helped delineate multiple channel belts and a point bar complex that informed the final facies models.
Qualitative Comparison of Offset Surfaces Between the Central and Eastern Gar...Tom Crane
This study analyzes and compares offset surfaces along the central and eastern segments of the Garlock fault in California using LiDAR data and imagery. Qualitative methods were used to establish relative ages of alluvial surfaces based on characteristics like height, shape, dissection, surface darkness, and smoothness. Measured offsets of surfaces of similar inferred ages along the central fault were greater than for the eastern fault, suggesting a reduction in slip rate eastward. Preliminary slip rate estimates are 4.2 mm/yr for the central fault and 1.0 mm/yr for the eastern fault, indicating a decreasing rate from west to east along the fault. OSL dating of samples will provide firmer slip rate calculations to verify
- The project aimed to understand the failure of a 6-day forecast over Europe in April 2011 by examining convection over North America. The forecast significantly underestimated convection from an MCS over the central US on April 10th.
- Verification showed the forecast error in the OpenIFS model. Examining fields like CAPE and precipitation revealed errors in the location and timing of convection in the forecast.
- A 5-member ensemble was run but none improved on the control forecast, all overestimated blocking over Europe. The ensemble mean performed worse than the control forecast. Perturbations in the initial conditions had little impact on the forecasts.
This study uses basin modelling to analyze the hydrocarbon potential of two Neogene sedimentary sub-basins in southern Hungary. The modelling simulated the subsidence and thermal maturation histories. It determined that the southern sub-basin reached greater depths and temperatures, resulting in gas generation from source rocks beginning 11.6 million years ago. Oil generation in the northern sub-basin began more recently around 6.8 million years ago. While hydrocarbons migrated upward along faults, accumulations have only formed so far in the southern sub-basin within anticline structures in carbonate formations. The complex geological evolution and thermal anomalies revealed by the modelling provide new perspectives for hydrocarbon exploration in the area.
Surface Reflection Seismic Method: Coal Mines FieldAli Osman Öncel
This document summarizes a study that used seismic modeling and analysis of seismic data to interpret the stratigraphy of a shallow coal deposit in central Alberta, Canada. 1D and 2D modeling helped relate seismic reflection character to stratigraphic variations in the coal zone. Seismic lines from the study area were reprocessed and interpreted, finding that reflection character could be quantitatively related to coal zone stratigraphy. The study demonstrated that detailed seismic interpretation is possible by relating reflection seismic data to variations in density logs from wells.
Fault Tectonics of the NE Black Sea Shelf and Its Relevance to Hydrocarbon Po...Şarlatan Avcısı
Abstract
Although faults of the consolidated crust play crucial role in the origin of sedimentary features and hydrocarbon accumulation, the tectonic setting of the NE Black Sea shelf is poorly known. The aim of this work is to compile the most detailed map of faults in the consolidated crust and test comprehensively a linkage between crustal disturbances and potential hydrocarbon features. Understanding such a relationship may be helpful in planning location of exploration boreholes.
For the first time, 3D gravity and magnetic models have been obtained at a scale of 1:200,000 for the NE Black Sea shelf. Based on the analysis of the observed magnetic field and gravity effect of the consolidated crust, the most detailed map has bееn compiled for tectonic faults of the consolidated crust. The relationship has been derived between the crustal and sedimentary faults. The prospective local anticlinal features have been revealed to be associated with certain systems of tectonic disturbances in the different crustal layers and magnetic inhomogeneity in the crust. The magnetic bodies of the consolidated crust and sedimentary cover can be of common origin due to
the influence of hydrocarbons vertically migrating along the deep faults. An individual block of high density has been delimited by the faults in the consolidated crust where there occur practically all prospective hydrocarbon features. The southern margin of this block is recommended as a new potential area for oil and gas exploration where gas seeps
are genetically related to the tectonic disturbances of different orders.
A first model has been derived for thermal evolution of the Kerch-Taman Trough from the pseudo-well method. A total subsidence of its basement can reach 5.0-6.5 km. The present-day temperature vs. depth profiles have been calculated. A thermal and stratigraphic position
has been determined for zones of oil and gas origin.
source : V.I. Starostenko1, B.L. Krupskyi1, I.K. Pashkevich1, O.M. Rusakov1,
I.B. Makarenko1, R.I. Kutas1, V.V Gladun1, O.V. Legostaeva1, T.V. Lebed1, and
P.Ya. Maksymchuk1
Search and Discovery Article #30155 (2011) Posted March 28, 2011
*Adapted from oral presentation at AAPG European Region Annual Conference, Kiev, Ukraine, October 17-19, 2010
1Institute of Geophysics, National Academy of Sciences of Ukraine, National Joint stock-Company Naftogaz of Ukraine, Kyiv, Ukraine
This study examines how the interpretation of drumlins in areas surrounding Lake Simcoe, Ontario changes when using different topographic maps and digital elevation models over time. The researchers analyzed drumlin features in three regions - an urban area on sand plains, a rural clay plain area, and a till plain region - using topographic maps from different years and a DEM. They found that while early topographic maps and the DEM displayed similar detail, drumlins appeared to erode over time, likely due to urbanization and the underlying sediment type. Later topographic maps had less detail than same-resolution DEMs, suggesting topographic maps are not as reliable for drumlin mapping as other digital tools.
Northern larsen ice shelf Antarctica: further retreat after collapseSimoneBoccuccia
This document discusses changes to glaciers and ice shelves in northern Larsen Ice Shelf, Antarctica after the collapse of parts of the ice shelf in 1995. It finds that large glaciers retreated several kilometers inland from their previous grounding lines after losing the back pressure from the ice shelves. Interferometry showed the main glacier in the area, Drygalski Glacier, accelerated its flow speed up to three times over 4 years after ice shelf collapse. Other grounded glaciers also saw accelerations, suggesting ice shelf collapse could contribute to sea level rise. The document also documents further retreat of Larsen B ice shelf through October 2000.
This document provides an outline of a PhD project aiming to assess the shallow geothermal potential of Northern Ireland. The project has three main aims: 1) audit the shallow geothermal resource, 2) grade areas based on their economic heat potential, and 3) progress high-potential options to a business case. The researcher will develop screening criteria for sites and geologically map focus areas to characterize aquifers. Maps of permeable rock units and groundwater data will be used to create a shallow geothermal potential map. Proglacial sediments like deltas, eskers and outwash plains provide the most prospective reservoirs due to their high permeability. The researcher has identified the Malone Sands delta near Belfast and Kil
Why core the Quaternary of the North Sea? An overview/context of the GlaciStore scientific objectives - presentation by Hans-Petter Sejrup (University of Bergen) at the UKCCSRC Glacistore Meeting "Impact of glacial advances and retreats on the strata overlying prospective North Sea CO2 storage sites", 27 February 2015
The document discusses satellite radar altimeter measurements of elevation changes in the Larsen Ice Shelf between 1992 and 2001. It finds that the ice shelf lowered by up to 0.27 meters per year on average. This thinning is explained by increased summer meltwater and loss of basal ice through melting. Enhanced ocean-driven melting may provide a link between regional climate warming and the successive breakup of sections of the Larsen Ice Shelf. Testing rules out other potential causes of thinning like changes in sea level, ocean density, or surface accumulation. The long-term thinning observed suggests meltwater production alone does not account for the lowering, indicating additional thinning mechanisms are also involved.
This document summarizes a geology dissertation on South Raasay, Scotland. Nine sedimentary and three igneous formations were mapped in the area. The sedimentary basement consists of braided river sandstones and conglomerates from the Torridonian period, unconformably overlain by shallow to deep marine Jurassic mudstones and sandstones. Two marine transgressions and regressions are proposed. The succession has been intruded by a granophyre sill, microgabbro sill, and basaltic dykes associated with the North Atlantic Igneous Province. During the Tertiary, regional extension resulted in prominent normal and strike-slip faults. Recent glaciation is evident from erratics and till.
Exposed subsurface ice sheets in the Martian mid-latitudesSérgio Sacani
Thick deposits cover broad regions of the Martian mid-latitudes with a smooth mantle; erosion
in these regions creates scarps that expose the internal structure of the mantle.We
investigated eight of these locations and found that they expose deposits of water ice that
can be >100 meters thick, extending downward from depths as shallow as 1 to 2 meters below
the surface.The scarps are actively retreating because of sublimation of the exposed water
ice.The ice deposits likely originated as snowfall during Mars’ high-obliquity periods and have
now compacted into massive, fractured, and layered ice.We expect the vertical structure of
Martian ice-rich deposits to preserve a record of ice deposition and past climate.
Paleofluvial mega canyon_beneath_the_central_greenland_ice_sheetSérgio Sacani
1) Researchers have discovered a 750-km long subglacial canyon beneath the central Greenland ice sheet using ice-penetrating radar data.
2) The canyon has a depth of up to 800 m and width of up to 10 km near the coast, and likely influenced basal water flow beneath the ice sheet over past glacial cycles.
3) Modeling of hydraulic potential suggests the canyon provided a pathway for subglacial water flow both before and during ice sheet formation, influencing the basal hydrology of northern Greenland.
Complex Antarctic ice-shelf height changes revealed by eighteen years of sate...Fernando Paolo
1) 18 years of satellite radar altimetry data from 1994-2012 show that Antarctic ice shelves have experienced significant thickness changes over that period.
2) Overall, the rate of volume loss from Antarctic ice shelves accelerated in the last decade, with West Antarctic ice shelves losing volume at a rate that increased by around 70% since 2003.
3) Some West Antarctic ice shelves have lost up to 18% of their thickness in the past 18 years, indicating accelerated thinning.
A large impact crater beneath Hiawatha Glacier in northwest GreenlandSérgio Sacani
We report the discovery of a large impact crater beneath Hiawatha Glacier in northwest Greenland. From airborne radar surveys, we identify a 31-kilometer-wide, circular bedrock depression beneath up to a kilometer of ice. This depression has an elevated rim that cross-cuts tributary subglacial channels and a subdued central uplift that appears to be actively eroding. From ground investigations of the deglaciated foreland, we identify overprinted structures within Precambrian bedrock along the ice margin that strike tangent to the subglacial rim. Glaciofluvial sediment from the largest river draining the crater contains shocked quartz and other impact- related grains. Geochemical analysis of this sediment indicates that the impactor was a fractionated iron aster- oid, which must have been more than a kilometer wide to produce the identified crater. Radiostratigraphy of the ice in the crater shows that the Holocene ice is continuous and conformable, but all deeper and older ice appears to be debris rich or heavily disturbed. The age of this impact crater is presently unknown, but from our geological and geophysical evidence, we conclude that it is unlikely to predate the Pleistocene inception of the Greenland Ice Sheet.
Application of Satellite Geodesy in Environmental and Climate ChangesAlok Verma
Satellite geodesy uses satellites to measure the shape and gravity of Earth. Satellite techniques like altimetry, GPS, InSAR, and GRACE monitor environmental changes from ice sheet mass balance, coastal uplift, and ground deformation. Studies using these techniques show increases in ice melt from Greenland and Antarctica, contributing to rising sea levels. InSAR effectively monitors surface changes from fluid injection into reservoirs.
This study analyzed observed sea ice trends from 1980-2008 to evaluate regional variations and identify optimal climate models. Key findings:
1) Winter sea ice extent in the Atlantic region declined significantly faster than other regions, at a rate of 8.6% per decade.
2) A lead-lag analysis found warmer Atlantic Ocean temperatures were associated with reduced winter sea ice extent in that region.
3) Thirteen climate models were evaluated based on their ability to hindcast observed pan-Arctic and regional sea ice trends. The best performing models were selected to project future sea ice changes.
4) Projections from the selected models suggest reduced sea ice cover along the Northwest and Northeast Passages, with potential
Variations in the amount of water ice on Ceres’ surface suggest a seasonal wa...Sérgio Sacani
The dwarf planet Ceres is known to host a considerable amount of water in its interior, and areas of water ice were
detected by the Dawn spacecraft on its surface. Moreover, sporadic water and hydroxyl emissions have been observed
from space telescopes. We report the detection of water ice in a mid-latitude crater and its unexpected variation
with time. The Dawn spectrometer data show a change of water ice signatures over a period of 6 months,
which is well modeled as ~2-km2 increase of water ice. The observed increase, coupled with Ceres’ orbital parameters,
points to an ongoing process that seems correlated with solar flux. The reported variation on Ceres’ surface
indicates that this body is chemically and physically active at the present time.
This document presents a study on glacial lake outburst floods (GLOFs) in the upper Kosi catchment region of Nepal. The objectives are to create land use/land cover maps, map glaciers and proglacial lakes from 1989, 2001, and 2010 using satellite imagery, and analyze the temporal variation and relationship between glaciers and proglacial lakes. Landsat, LISS-3, LISS-4, and Cartosat data will be used. The anticipated results are temporal variation in glaciers and proglacial lakes over the study period, and determining the relationship between proglacial lake formation and glacier shrinkage.
The Pan-Arctic Impacts of Thinning Sea IceZachary Labe
The Arctic is rapidly changing. However, long-term observations of trends in Arctic sea-ice thickness are still quite limited. In this presentation, Zachary will discuss the different methods (satellite instruments and climate model simulations) of observing sea-ice thickness in order to understand changes in the recent Arctic amplification era. He will also highlight the far-reaching environmental and societal impacts from a thinning Arctic sea-ice cover.
The glaciation of the North Sea Basin and its implications for Carbon Capture and Storage sites - presentation by Tom Bradwell (BGS/University of Stirling) at the UKCCSRC Glacistore meeting "Impact of glacial advances and retreats on the strata overlying prospective North Sea CO2 storage sites", 27 February 2015
Sea levels have changed dynamically throughout the Holocene epoch due to the interplay between absolute sea level changes and vertical land movement. As ice sheets melted after the last glacial period, sea levels rose globally from -130m to current levels through a combination of glacio-eustatic sea level rise and local glacio-isostatic land rebound and subsidence. Records of past sea level changes are reconstructed from dated geological indicators to develop sea level curves. Interpreting these indicators requires understanding their relationship to contemporaneous tide levels.
This dissertation examines how well the pattern of glaciation during the Loch Lomond Stadial (LLS) ~12.9-11.5ka BP represents long-term glacial erosion in Scotland. The author uses a numerical ice sheet model of the LLS to infer erosion and compares this to valley morphology data from Glen Lyon. Results show valley cross-profiles and overdeepened basins support multiple glaciation styles, with erosion influenced by preglacial topography and ice sheet growth/decay. While the LLS provides insights, the long-term pattern is complex, reflecting various stadial glaciations. Future work could provide a more holistic understanding by incorporating data from the larger Late Devens
1. Examining dynamics, extent and timings of the British Ice SheetExamining dynamics, extent and timings of the British Ice Sheet
during the Last Glacial Maximumduring the Last Glacial Maximumduring the Last Glacial Maximum
Emma Reynolds, Department of Earth Sciences, Durham UniversityEmma Reynolds, Department of Earth Sciences, Durham University
1. INTRODUCTION 5. LIMITATIONS4. RESULTS & DISCUSSIONS I; dynamics
To examine nature of the BIS, the Alston Block area in northern England was zoomed in upon, showing ice
3°0'0"E2°5'0"W7°10'0"W
60°0'0"N 60°0'0"N
35,000 years ago, Britain was ice-free, when growth of
plateau ice fields started until the height of the last ice age.
Field observations indicate that the ice cap slowly advanced
•DEMs: Resolution was maximum 30m and so landforms are hazy. But,
with funding, 5m resolution is available. The inconsistencies between
DEM tiles are rectified by mosaicking, but cannot be projected into
To examine nature of the BIS, the Alston Block area in northern England was zoomed in upon, showing ice
dynamics on a macroscopic scale. Analysis revealed complex flow patterns, individual glacier dynamics, and a
late readvance.
Figure 3; Map showing
line of maximum extent
of the BIS, dependent
60°0'0"N
Field observations indicate that the ice cap slowly advanced
and then retreated due to climate change.
This project involved creating and analysing datasets, using
DEM tiles are rectified by mosaicking, but cannot be projected into
ArcScene. On ASTER DEMs, some clouded areas appear bright and
water bodies can have several elevation values2. Therefore, these
Glacier nature
Fluvial erosional and depositional features such as drumlins, eskers and subglacial channels over the UK
late readvance.of the BIS, dependent
upon locations of glacial
landforms over the UK1.
This project involved creating and analysing datasets, using
techniques of GIS cartography and spatial analysis. This was
to a) examine the dynamics of the ice sheet, using an area of
Northern England, and b) determine maximum ice extent of
water bodies can have several elevation values2. Therefore, these
could be manually edited, similar to other DEM sources.
•BRITICE: Incomplete, patchy coverage, variable approaches, and
spans centuries of field research; a solution is to map all landforms
Fluvial erosional and depositional features such as drumlins, eskers and subglacial channels over the UK
(Figure 3) indicate water presence, proving subsurface reached sufficient temperatures and pressures for a
warm base. Anastomosing inset valleys sub-parallel to contours (Figure 5) indicate supraglacial lateral57°55'0"N 57°55'0"N
Northern England, and b) determine maximum ice extent of
the British Ice Sheet (BIS) during the Last Glacial Maximum
(LGM), and the dates associated with it.
spans centuries of field research; a solution is to map all landforms
from satellite images5. These uncertainties apply to isochron dataset
(basis from BRITICE).
warm base. Anastomosing inset valleys sub-parallel to contours (Figure 5) indicate supraglacial lateral
channels, thus erosion from surface meltwater instead of ice – a cold-based glacial system, especially
during retreat. Figure 5 shows lateral channels to be
(LGM), and the dates associated with it. (basis from BRITICE).
•My interpretations: Creating ischron dataset was subjective;
systematic quantitative moraine dating could minimise limitations. My
2. METHODS
during retreat. Figure 5 shows lateral channels to be
only in upland areas.
Interpretation: BIS was warm-
based except in few upland areas
Lateral channels running
parallel to contours
Figure 5; Lateral
channels sub-parallel to
65
55°50'0"N 55°50'0"N
systematic quantitative moraine dating could minimise limitations. My
line of extent is subjective; averaging several glaciologists’
interpretations would be more accurate.
•Timing for LGM: Time-transgressive nature of the BIS advance and
2. METHODS
Data sources
based except in few upland areas
where ice sheet was much thinner.
channels sub-parallel to
contours.
65 •Timing for LGM: Time-transgressive nature of the BIS advance and
dynamic nature of different ice centers causes different margins to
reach maximum extent at different times8. Complete ice coverage is
Data sources
Three datasets were needed:
1.The BRITICE project1; thematic layers of different UK glacial
landforms.
53°45'0"N 53°45'0"N
reach maximum extent at different times8. Complete ice coverage is
assumed behind each isochron (Figure 3), particularly during early
growth and late retreat where ice only existed in upland areas. To
reduce uncertainty, a more detailed analysis from greater number of
landforms.
2.DEMs; sourced from ASTER2 (30m resolution), CGIAR3 (90m
resolution) and NERC Bluesky4 (5m resolution).
Complex flow patterns
Cross-cutting drumlins indicate changing flow
Eden Valley
Solway
Stainmore Gap
reduce uncertainty, a more detailed analysis from greater number of
sites is needed.
resolution) and NERC Bluesky4 (5m resolution).
3.Dated glacial sites; a new dataset of chronological lines was
created, based upon site locations5,6 using average ages for
Cross-cutting drumlins indicate changing flow
directions. Lower drumlins show earlier south
flow up Eden Valley and over Stainmore Gap,
51°40'0"N 51°40'0"N
Data preparation
created, based upon site locations using average ages for
advance and terminus sites.
6. CONCLUSIONS
Line of
maximum
extent
flow up Eden Valley and over Stainmore Gap,
overprinted by later west flow towards Solway.
Figure 4; Carboniferous Alston Block area. Arrows showing Interpretation: During retreat of the BIS, main
65
Data preparation
All datasets were combined together into a readable format.
After unzipping, DEMs were mosaicked using Data
Management Tools in ArcCatalog. Coordinate systems were
6. CONCLUSIONS
The dynamics of the British Ice Sheet at the Last Glacial Maximum
were very variable. The BIS was heterogenous in extent and nature,
extent
(thick blue)
Late readvance
Figure 4; Carboniferous Alston Block area. Arrows showing
zoomed-in locations discussed.
Interpretation: During retreat of the BIS, main
Scottish ice flow was overrun by regional radial
ice dispersal centers; Pennines
65Management Tools in ArcCatalog. Coordinate systems were
aligned; DEMs were WGS_1984, BRITICE data was BNG OS_36.
Using ArcToolbox, new projections were defined for each layer
were very variable. The BIS was heterogenous in extent and nature,
reaching maximum at different times. Dynamics are summarised
below in different evolutionary stages, using the Pennines and Lake
Late readvance
Elongated drumlins in the Solway dated at 17 Ka
show south flow drawn west towards water bodies. A
ice dispersal centers; Pennines
and Lake District. Can assume
opposite occurred during
growth.
0 50 100 150 20025
Kilometers
3°0'0"E2°5'0"W7°10'0"W
Using ArcToolbox, new projections were defined for each layer
in the BRITICE dataset, to configure the entire dataframe to
WGS_1984. Isochron dataset was georeferenced to relate to
below in different evolutionary stages, using the Pennines and Lake
District to represent the UK (Figure 9):
GROWTH
show south flow drawn west towards water bodies. A
push moraine south supports Scottish flow direction.
i)Interpretation: Flow was
growth.
i)
Data analysis
WGS_1984. Isochron dataset was georeferenced to relate to
the others.
GROWTH
Upland areas such as the Lake District and Pennines
initiated growth of plateau ice fields. These terrain
surfaces were glaciated thinly very fast, then spilled
i)Interpretation: Flow was
south but drawn towards
Irish Sea, at a time ScottishData analysis
Analysis was split up into elements for each part of the
question.
surfaces were glaciated thinly very fast, then spilled
over into surrounding valleys by radial regional flow
(Figure 9 i)) to become thick, warm-based glaciers.
Scottish
readvance
south
Flow drawn
westwards
Irish Sea, at a time
when local flow
should be dominant.
Thus, a late re-
Scottish
flow south Regional flow
west
question.
a) To investigate ice sheet dynamics: i) Individual glacier
nature; different erosional features were looked at in 3D. ii)
Complex flow patterns; aerial imagery and DEM data was
LGM
During full glaciation at 27 Ka, southerly Scottish
south
westwards
Thus, a late re-
advance of Scottish
ice, unconstrained
ii)
Complex flow patterns; aerial imagery and DEM data was
combined with drumlin data and projected in ArcScene (Figure
1) to determine flow sequences. iii) Late readvance; drumlins
During full glaciation at 27 Ka, southerly Scottish
ice flow was dominant, overprinting local patterns
(Figure 9 ii)). The BIS extended south as far as
southern Wales and the Wash, although mid-
Push
moraine
ii)
ice, unconstrained
by topographic influence. Figure 6; Two different main flow directions
inferred from drumlin orientations. Inset:
NEXTMap image showing cross-cuttingFigure 7; i) Drumlin flow1) to determine flow sequences. iii) Late readvance; drumlins
and moraines were draped over DEMs in ArcScene to examine
ice dominance.
southern Wales and the Wash, although mid-
landmass it v’d, only reaching the Peak District.
NEXTMap4 image showing cross-cutting
drumlins (red: Scottish overprinting, green:
early local flow).
Figure 7; i) Drumlin flow
mainly south but drawn towards sea. ii) Push moraine (south orient-
ation) supports southerly flow. Inset: NEXTMap4 image showing detail.
iii)
ice dominance.
RETREAT
Figure 2; Editing vertices
on extent shapefile.
3. RESULTS & DISCUSSIONS II; extent & timing
Figure 9; i) ii)
and iii)
Summary
iii)
65
RETREAT
After 27 Ka, the ice sheet started to retreat, reaching a minimum at 14 Ka.
Conversely to growth, regional dispersal centres became more influential, and
upland areas were last to be ice-free, (curve on Figure 9 iii)) leaving some
on extent shapefile.
3. RESULTS & DISCUSSIONS II; extent & timing
To answer the question of extent, the isochron map shown in Figure 8 was
produced from analysis of glacial site dates. Analysis of the oldest isochron in
Summary
maps with
major flow
(blue arrows)65 upland areas were last to be ice-free, (curve on Figure 9 iii)) leaving some
zones in the south isolated. At 17 Ka, there was a late readvance of Scottish ice.
Location
produced from analysis of glacial site dates. Analysis of the oldest isochron in
showed a correlation with the line of maximum extent from Figure 3.
(blue arrows)
and ice cover.
Figure 1;
65
Location
Line of maximum extent was drawn primarily around ice terminus features;
moraines, lateral meltwater channels, eskers, and ice-dammed lakes. These
7. REFERENCES
Figure 1;
Projection in ArcScene.
65
moraines, lateral meltwater channels, eskers, and ice-dammed lakes. These
marginal features imply extension backwards of the ice sheet, if complete
coverage is assumed.
Line of
maximum
extent
(thick blue)
[1] Clark, C.D., Evans, D.J.A., Khatwa, A., Bradwell, T., Jordan, C.J., Marsh, S.H., Mitchell, W.A., and Bateman., M.D. (2004) Map and GIS
database of landforms and features related to the last British Ice Sheet. Boreas, 33(4), 359-375.
[2] ASTER GDEM data product is courtesy of an online data pool from METI and NASA.
b) To investigate maximum glacial extent and timing: i) Timing;
isochrons were defined based upon groups of similar dates,
converted from point to line data in ArcMap. ii) Location;
65
Timing
Figure 8 shows maximum ice extent to have occurred at approximately 27 Ka.
(thick blue)
[2] ASTER GDEM data product is courtesy of an online data pool from METI and NASA.
[3] Jarvis, A., Reuter, H.I., Nelson, A. And Guevara, E. (2008) Hole-filled SRTM for the glove Version 4, available from CGIAR-CSI SRTM
90m Database (http://srtm.csi.cgiar.org).
[4] NEXTMap Britain data from Intermap Technologies Inc., provided courtesy of NERC via the NERC Earth Observation Data Centre
(NEODC).converted from point to line data in ArcMap. ii) Location;
landforms focused upon as diagnostic of the BIS margin were
terminal and marginal – moraines, meltwater channels, eskers,
Figure 8 shows maximum ice extent to have occurred at approximately 27 Ka.
After reaching a maximum, the BIS is shown to retreat in Figure 8 until 15 Ka,
implying that the LGM was very short, due to the sensitivity of the UK as a0 50 100 150 20025
Kilometers
(NEODC).
[5] Clark, C.D., Hughes, A.L., Greenwood, S.L., Jordan, C. And Sejrup, H.P. (2012) Pattern and timing of the retreat of the last British-
Irish ice sheet. Quaternary Science Reviews, 44, 112-146.
[6] Hughes, A.L.C., Greenwood, S.L. And Clark, C.D. (2011) Dating constraints on the last British-Irish Ice Sheet: a map and a database.terminal and marginal – moraines, meltwater channels, eskers,
tunnel valleys and ice-dammed lakes. In ArcMap, a shapefile
was drawn along moraine boundaries (Figure 2) and adjusted
implying that the LGM was very short, due to the sensitivity of the UK as a
climate receptor7. Retreat was at a steady rate, although margin variation was
due to water presence. Outlying upland areas are left whilst ice retreats rapidly
across water.
Figure 8; Map showing retreat isochrons, ice distribution centers (white
lines) and flow directions (blue arrows) overlaid onto CGIAR DEMs .
Kilometers
[6] Hughes, A.L.C., Greenwood, S.L. And Clark, C.D. (2011) Dating constraints on the last British-Irish Ice Sheet: a map and a database.
Journal of Maps, v2011, 156-183.
[7] Evans, D.J.A., Livingstone, S.J., Veili, A. And O Cofaigh, C. (2009) The paleoglaciology of the central sector of the British and Irish Ice
Sheet: reconciling glacial geomorphology and preliminary ice sheet modelling. Quaternary Science Reviews, 28, 740-758.was drawn along moraine boundaries (Figure 2) and adjusted
using other features for best fit.
across water.lines) and flow directions (blue arrows) overlaid onto CGIAR DEMs3. Sheet: reconciling glacial geomorphology and preliminary ice sheet modelling. Quaternary Science Reviews, 28, 740-758.
[8] Evans, D.J.A. And Stokes, C. (2015) Personal communication on field trip 7th Feb 2015.