John Menzies | Brock University (original) (raw)

Papers by John Menzies

Austrian Journal of Earth Sciences

Fast moving palaeo-ice masses within the European Alpine Ice Cap (EAIC) during the Last Glacial M... more Fast moving palaeo-ice masses within the European Alpine Ice Cap (EAIC) during the Last Glacial Maximum within the large valleys of the European Alps are likely comparable in terms of their subglacial conditions to ice streams that drained the larger Quaternary Ice Sheets in Europe and North America. Unlike these continental-style ice sheets, the ice inundating the European Alps, like the Cordilleran Ice Sheet in North America, flowed through confined bedrock valleys that, at close to the glacial maximum, acted in a similar manner to ice streams. Little mention exists as to the extent of soft sediment basal deformation in these deep valleys although increasingly such conditions are known from several parts of the EAIC. The Drau (Drava) ice stream during the Alpine Last Glacial Maximum (= Würmian Pleniglacial, ~ 29 – ~20 ka) as well as small tributary glacier during the early Lateglacial phase of ice decay (~20 – 19 ka) appears as a temperate, fast-moving ice mass that would likely b...

Canadian Journal of Earth Sciences, 2018

The past-producing Pine Point lead–zinc mining district, Northwest Territories, Canada, provides ... more The past-producing Pine Point lead–zinc mining district, Northwest Territories, Canada, provides a unique opportunity to study the role of glacial dynamics in a thick, continuous till succession that has not been influenced by the underlying bedrock topography. Parts of the Pine Point mining district are covered by >20 m of subglacial Quaternary sediments (till) associated with the former Laurentide Ice Sheet. Till facies exposed in unreclaimed open-pit K-62 have been classified into four separate units. Micro- and macrosedimentological analyses were undertaken to identify the change in subglacial stress during sediment deposition and across till unit boundaries. An analysis of high- and low-angle microshears (lineations) in thin sections produced from these till units indicate that there is a noticeable decrease in the abundance of low-angle shear features immediately below till unit boundaries. The deformation of low-angle shears in the underlying tills was likely caused by rem...

The Depositional Record, 2019

Investigations of glacial sediment exposures in a former open pit in the Pine Point Mining Distri... more Investigations of glacial sediment exposures in a former open pit in the Pine Point Mining District, Northwest Territories, reveal evidence of changes in stress magnitude as exhibited by the movement of deformation 'fronts' within subglacial tills, as evident through micromorphological analysis. Indications of deformation, driven by stress fluctuations, were observed throughout a set of vertical subglacial till samples associated with the Laurentide Ice Sheet (LIS). These tills exhibit multiple sublithofacies variations in concert with marked changes in microshear orientation, which can be directly related to changing stress levels within a subglacial deforming bed. The evidence of changes in till stress conditions is typical of subglacial tills occurring beneath an active temperate ice mass within a soft deforming bed. As differing 'layers' of till that form a mosaic-like pattern, become immobilized and 'detached' subjacent to the deforming bed sediments, a signature of this action is recorded within the tills as sequences of specific microstructures. These microstructures are part of a spectrum of micro-forms that develop as consequence of changes in stress, porewater content, and clay content within the 'fault-gouge'-like environment formed beneath an active temperate ice sheet. A model is developed that uses data from Pit O-28 demonstrating where deformation 'boundary front' evidence in the form of deformation bands has developed as basal driven stress levels have penetrated active deforming sediments. The evidence from Pine Point indicates that till acts as an excellent palaeostrain record of past active glacial processes, subglacial basal thermal conditions and sediment mobility.

Sedimentary Geology, 2010

Valley glaciers have been well studied in the northwestern Venezuelan Andes over the last 20-year... more Valley glaciers have been well studied in the northwestern Venezuelan Andes over the last 20-year period with most sourcing reconstructions limited to the Last Glacial Maximum (LGM) and confined to the mapping of moraine positions and the detailed analysis of pedostratigraphic sequences reaching back into the Middle Wisconsinan (Weichselian) Glaciation. Using bedding macrofeatures, fabric analysis (magnetic azimuths) with mirror images, clast inclination and microtextural evidence determined with the FE-SEM (Field Emission Scanning Electron Microscopy) and EDS (Energy Dispersive Spectroscopy), and micromorphology of the PED5 composite section of Early to Late Mérida age was analyzed to reconstruct the till succession and glacial dynamics. The fabric is used to reconstruct the build-up of valley ice in the lower Mucuñuque Valley, the icecap spreading over the upper catchments of neighbouring drainage basins toward the headwaters of the Mucuchache Valley over a time frame estimated to be b 90 ka and lasting to ∼ 60 ka. Microtextural analysis was invoked to determine if physical differences on quartz and garnet mineral surfaces could be determined between various diamictons such as subglacial, flow and meltout tills, and outwash. Sample identification was made optically and with EDS. The evidence supports the theory that a substantial ice massa virtual icecapexisted during the Early Mérida stade of the last glaciation with the ice mass originating and decaying from the upper Mucuñuque Catchment south over some 40°of arc. This is the first evidence for an icecap complex in the northwestern Andes. Comparison between Early and Late Mérida glacial styles indicates that, in the Mucuñuque-Mucuchache corridor of the Mérida Andes glaciation in the LGM was catchment restricted with no evidence of icecap growth.

Sedimentary Geology, 2010

Valley glaciers have been well studied in the northwestern Venezuelan Andes over the last 20-year... more Valley glaciers have been well studied in the northwestern Venezuelan Andes over the last 20-year period but most reconstructions have been limited to the Last Glacial Maximum (LGM). Analyses have been confined to the mapping of moraine positions and the detailed analysis of pedostratigraphic sequences reaching back through the Middle to the Early Wisconsinan (Weichselian) Glaciation. Using bedding macrofeatures, fabric analysis (magnetic azimuths) with mirror images, clast inclination and microtextural evidence much has been learned about the lithology, source of ice, growth of an ice cap in the eastern cordillera and weathered state of surface paleosols. Analysis of two sections of pre-Mérida age, the only two such sections known in the Sierra de Santa Domingo (eastern cordillera), provides new information on lithology, source of the ice and weathered state of sediment of pre-Mérida age. The fabric in these sections is used to deduce the build-up of valley ice in the lower El Caballo Valley from an ice cap similar to one that developed later in Early Mérida time (~90 ka to~65 ka). The presence of weathered tills in both sections suggests two glaciations perhaps correlative with the Illinoian and Kansan glaciations of North America. The weathered state of tills and outwash in both sections is assessed on the basis of geochemical (INAA) and mineral composition (XRD) and microtextural evidence determined by SEM/EDS.

Geology, 1981

The importance of the thermal characteristics of subglacial deformable debris is inferred from ef... more The importance of the thermal characteristics of subglacial deformable debris is inferred from effects on processes of deposition and erosion. There is a lack of information on the temperatures found within subglacial debris under present-day ice masses. Data ...

Sedimentary Geology

This introduction provides of a brief review of a set of papers based on a Special Symposium held... more This introduction provides of a brief review of a set of papers based on a Special Symposium held at the XII INQUA Congress, Ottawa, 1987. Attention is also drawn to the major concepts and controversies behind the formation of subglacial bedforms and to major issues for future research.

Journal of Glaciology

Most drumlins are composed of till that appears similar in all characteristics to non-drumlin til... more Most drumlins are composed of till that appears similar in all characteristics to non-drumlin till. Evidence, however, in the form of till layer sequences and from palaeomagnetic Koenigsberger ratios indicate that drumlin till may have a slightly higher pore-water content at the time of lodgement than nondrumlin till. In order that deposited till remains at the ice-glacier-bed interface to initiate drumlin formation, it must undergo rapid geotechnical changes whereby its pore-water content is dissipated thereby increasing the shear strength of the till. Two mechanisms of pore-water removal are possible. Firstly, pore water may be removed from localized patches within a mobile layer of till at the ice-glacier-bed interface, thus creating nuclei of higher-strength till around which deforming till may adhere. Secondly, removal of water initially from the thin water film at the base of a glacier may result in increased pressure melting of the ice leading to till melt-out and subsequent ...

Quaternary Science Reviews, Nov 1, 2012

Icebergs plough through unconsolidated lake/sea sediments gouging out kilometre long grooves, 100... more Icebergs plough through unconsolidated lake/sea sediments gouging out kilometre long grooves, 100s of metres wide and tens of metres deep. Although the surface morphology of iceberg scours is welldocumented, little is known about what scours look like in stratigraphic section, particularly where surface characteristics are absent (e.g. through decay or burial). This investigation establishes a definitive suite of diagnostic criteria for identifying iceberg scours in clays by macroscopically and microscopically (2D thin sections) examining sediment deformation below iceberg scours in former Glacial Lake Agassiz, Manitoba, Canada. Structures unequivocally attributed to iceberg scour in this investigation include subhorizontal microfabrics, folds, sheath folds, augen-shapes, normal faults, reverse/thrust faults, discrete shears, partially destroyed clasts, intraclasts type III, multiple domains, water escape structures, flow structures, unistrial plasmic fabric, dropstones, realigned bedding, and specific structural sequences. This research will be particularly valuable in palaeoenvironmental reconstruction and in predicting glacial dynamics. In addition, it may eventually aid structural engineering on polar shelves, which could be of great value to oil and gas companies.

Palaeogeogr Palaeoclimatol, 1992

Quaternary Science Reviews, 2003

Sedimentary Geology, 1989

In reviewing hypotheses of subglacial bed formation it becomes apparent that a close relationship... more In reviewing hypotheses of subglacial bed formation it becomes apparent that a close relationship must exist between the development of these bedforms and subglacial hydraulic conditions. A speculative classification of subglacial temperate beds is presented. Subglacial beds are subdivided into "H", "Q", and "M" beds. "H" beds are typically hard beds in which Upper interface meltwater activity dominates. "'M" beds are those in which soft or mobile subglacial debris conditions prevail and in which advective pervasive flow of saturated debris occurs. In "Q" beds both of the other bed types occur but are of a spatially and temporally transitory nature. Thus this latter bed type may be the most common beneath ice masses. It is under an "M"-bed state that many drumlin subglacial bedforms and associated forms are thought to develop. Discussion on the processes involved in mobile debris entrainment and the effect of changing rheological parameters are developed. It is argued that such bedform initiation occurs due to anisotropic rheological variations within the mobile debris setting up a 'feedback effect". Such conditions are thought to be found most likely at the Lower interface of a fast moving ice mass possibly typical of an ice stream. In using empirical analyses of mobile debris conditions a limited set of relationships between subglacial meltwater flux rates, basal ice velocity, debris porosity and bed width are established with reference to mobile debris thicknesses. Using this relationship, a set of possible parameter values that would allow bed formation to be achieved are presented. The impact of bed formation under these conditions upon possible sedimentological facies and deformation structures is postulated. The wider effect of "M"-bed conditions on subglacial sedimentology is introduced and the need to investigate subglacial hydraulic and bed conditions under past glaciations from the evidence of their glacial sediments and landforms emphasised.

Modern and Past Glacial Environments, 2002

Modern and Past Glacial Environments, 2002

Austrian Journal of Earth Sciences

Fast moving palaeo-ice masses within the European Alpine Ice Cap (EAIC) during the Last Glacial M... more Fast moving palaeo-ice masses within the European Alpine Ice Cap (EAIC) during the Last Glacial Maximum within the large valleys of the European Alps are likely comparable in terms of their subglacial conditions to ice streams that drained the larger Quaternary Ice Sheets in Europe and North America. Unlike these continental-style ice sheets, the ice inundating the European Alps, like the Cordilleran Ice Sheet in North America, flowed through confined bedrock valleys that, at close to the glacial maximum, acted in a similar manner to ice streams. Little mention exists as to the extent of soft sediment basal deformation in these deep valleys although increasingly such conditions are known from several parts of the EAIC. The Drau (Drava) ice stream during the Alpine Last Glacial Maximum (= Würmian Pleniglacial, ~ 29 – ~20 ka) as well as small tributary glacier during the early Lateglacial phase of ice decay (~20 – 19 ka) appears as a temperate, fast-moving ice mass that would likely b...

Canadian Journal of Earth Sciences, 2018

The past-producing Pine Point lead–zinc mining district, Northwest Territories, Canada, provides ... more The past-producing Pine Point lead–zinc mining district, Northwest Territories, Canada, provides a unique opportunity to study the role of glacial dynamics in a thick, continuous till succession that has not been influenced by the underlying bedrock topography. Parts of the Pine Point mining district are covered by >20 m of subglacial Quaternary sediments (till) associated with the former Laurentide Ice Sheet. Till facies exposed in unreclaimed open-pit K-62 have been classified into four separate units. Micro- and macrosedimentological analyses were undertaken to identify the change in subglacial stress during sediment deposition and across till unit boundaries. An analysis of high- and low-angle microshears (lineations) in thin sections produced from these till units indicate that there is a noticeable decrease in the abundance of low-angle shear features immediately below till unit boundaries. The deformation of low-angle shears in the underlying tills was likely caused by rem...

The Depositional Record, 2019

Investigations of glacial sediment exposures in a former open pit in the Pine Point Mining Distri... more Investigations of glacial sediment exposures in a former open pit in the Pine Point Mining District, Northwest Territories, reveal evidence of changes in stress magnitude as exhibited by the movement of deformation 'fronts' within subglacial tills, as evident through micromorphological analysis. Indications of deformation, driven by stress fluctuations, were observed throughout a set of vertical subglacial till samples associated with the Laurentide Ice Sheet (LIS). These tills exhibit multiple sublithofacies variations in concert with marked changes in microshear orientation, which can be directly related to changing stress levels within a subglacial deforming bed. The evidence of changes in till stress conditions is typical of subglacial tills occurring beneath an active temperate ice mass within a soft deforming bed. As differing 'layers' of till that form a mosaic-like pattern, become immobilized and 'detached' subjacent to the deforming bed sediments, a signature of this action is recorded within the tills as sequences of specific microstructures. These microstructures are part of a spectrum of micro-forms that develop as consequence of changes in stress, porewater content, and clay content within the 'fault-gouge'-like environment formed beneath an active temperate ice sheet. A model is developed that uses data from Pit O-28 demonstrating where deformation 'boundary front' evidence in the form of deformation bands has developed as basal driven stress levels have penetrated active deforming sediments. The evidence from Pine Point indicates that till acts as an excellent palaeostrain record of past active glacial processes, subglacial basal thermal conditions and sediment mobility.

Sedimentary Geology, 2010

Valley glaciers have been well studied in the northwestern Venezuelan Andes over the last 20-year... more Valley glaciers have been well studied in the northwestern Venezuelan Andes over the last 20-year period with most sourcing reconstructions limited to the Last Glacial Maximum (LGM) and confined to the mapping of moraine positions and the detailed analysis of pedostratigraphic sequences reaching back into the Middle Wisconsinan (Weichselian) Glaciation. Using bedding macrofeatures, fabric analysis (magnetic azimuths) with mirror images, clast inclination and microtextural evidence determined with the FE-SEM (Field Emission Scanning Electron Microscopy) and EDS (Energy Dispersive Spectroscopy), and micromorphology of the PED5 composite section of Early to Late Mérida age was analyzed to reconstruct the till succession and glacial dynamics. The fabric is used to reconstruct the build-up of valley ice in the lower Mucuñuque Valley, the icecap spreading over the upper catchments of neighbouring drainage basins toward the headwaters of the Mucuchache Valley over a time frame estimated to be b 90 ka and lasting to ∼ 60 ka. Microtextural analysis was invoked to determine if physical differences on quartz and garnet mineral surfaces could be determined between various diamictons such as subglacial, flow and meltout tills, and outwash. Sample identification was made optically and with EDS. The evidence supports the theory that a substantial ice massa virtual icecapexisted during the Early Mérida stade of the last glaciation with the ice mass originating and decaying from the upper Mucuñuque Catchment south over some 40°of arc. This is the first evidence for an icecap complex in the northwestern Andes. Comparison between Early and Late Mérida glacial styles indicates that, in the Mucuñuque-Mucuchache corridor of the Mérida Andes glaciation in the LGM was catchment restricted with no evidence of icecap growth.

Sedimentary Geology, 2010

Valley glaciers have been well studied in the northwestern Venezuelan Andes over the last 20-year... more Valley glaciers have been well studied in the northwestern Venezuelan Andes over the last 20-year period but most reconstructions have been limited to the Last Glacial Maximum (LGM). Analyses have been confined to the mapping of moraine positions and the detailed analysis of pedostratigraphic sequences reaching back through the Middle to the Early Wisconsinan (Weichselian) Glaciation. Using bedding macrofeatures, fabric analysis (magnetic azimuths) with mirror images, clast inclination and microtextural evidence much has been learned about the lithology, source of ice, growth of an ice cap in the eastern cordillera and weathered state of surface paleosols. Analysis of two sections of pre-Mérida age, the only two such sections known in the Sierra de Santa Domingo (eastern cordillera), provides new information on lithology, source of the ice and weathered state of sediment of pre-Mérida age. The fabric in these sections is used to deduce the build-up of valley ice in the lower El Caballo Valley from an ice cap similar to one that developed later in Early Mérida time (~90 ka to~65 ka). The presence of weathered tills in both sections suggests two glaciations perhaps correlative with the Illinoian and Kansan glaciations of North America. The weathered state of tills and outwash in both sections is assessed on the basis of geochemical (INAA) and mineral composition (XRD) and microtextural evidence determined by SEM/EDS.

Geology, 1981

The importance of the thermal characteristics of subglacial deformable debris is inferred from ef... more The importance of the thermal characteristics of subglacial deformable debris is inferred from effects on processes of deposition and erosion. There is a lack of information on the temperatures found within subglacial debris under present-day ice masses. Data ...

Sedimentary Geology

This introduction provides of a brief review of a set of papers based on a Special Symposium held... more This introduction provides of a brief review of a set of papers based on a Special Symposium held at the XII INQUA Congress, Ottawa, 1987. Attention is also drawn to the major concepts and controversies behind the formation of subglacial bedforms and to major issues for future research.

Journal of Glaciology

Most drumlins are composed of till that appears similar in all characteristics to non-drumlin til... more Most drumlins are composed of till that appears similar in all characteristics to non-drumlin till. Evidence, however, in the form of till layer sequences and from palaeomagnetic Koenigsberger ratios indicate that drumlin till may have a slightly higher pore-water content at the time of lodgement than nondrumlin till. In order that deposited till remains at the ice-glacier-bed interface to initiate drumlin formation, it must undergo rapid geotechnical changes whereby its pore-water content is dissipated thereby increasing the shear strength of the till. Two mechanisms of pore-water removal are possible. Firstly, pore water may be removed from localized patches within a mobile layer of till at the ice-glacier-bed interface, thus creating nuclei of higher-strength till around which deforming till may adhere. Secondly, removal of water initially from the thin water film at the base of a glacier may result in increased pressure melting of the ice leading to till melt-out and subsequent ...

Quaternary Science Reviews, Nov 1, 2012

Icebergs plough through unconsolidated lake/sea sediments gouging out kilometre long grooves, 100... more Icebergs plough through unconsolidated lake/sea sediments gouging out kilometre long grooves, 100s of metres wide and tens of metres deep. Although the surface morphology of iceberg scours is welldocumented, little is known about what scours look like in stratigraphic section, particularly where surface characteristics are absent (e.g. through decay or burial). This investigation establishes a definitive suite of diagnostic criteria for identifying iceberg scours in clays by macroscopically and microscopically (2D thin sections) examining sediment deformation below iceberg scours in former Glacial Lake Agassiz, Manitoba, Canada. Structures unequivocally attributed to iceberg scour in this investigation include subhorizontal microfabrics, folds, sheath folds, augen-shapes, normal faults, reverse/thrust faults, discrete shears, partially destroyed clasts, intraclasts type III, multiple domains, water escape structures, flow structures, unistrial plasmic fabric, dropstones, realigned bedding, and specific structural sequences. This research will be particularly valuable in palaeoenvironmental reconstruction and in predicting glacial dynamics. In addition, it may eventually aid structural engineering on polar shelves, which could be of great value to oil and gas companies.

Palaeogeogr Palaeoclimatol, 1992

Quaternary Science Reviews, 2003

Sedimentary Geology, 1989

In reviewing hypotheses of subglacial bed formation it becomes apparent that a close relationship... more In reviewing hypotheses of subglacial bed formation it becomes apparent that a close relationship must exist between the development of these bedforms and subglacial hydraulic conditions. A speculative classification of subglacial temperate beds is presented. Subglacial beds are subdivided into "H", "Q", and "M" beds. "H" beds are typically hard beds in which Upper interface meltwater activity dominates. "'M" beds are those in which soft or mobile subglacial debris conditions prevail and in which advective pervasive flow of saturated debris occurs. In "Q" beds both of the other bed types occur but are of a spatially and temporally transitory nature. Thus this latter bed type may be the most common beneath ice masses. It is under an "M"-bed state that many drumlin subglacial bedforms and associated forms are thought to develop. Discussion on the processes involved in mobile debris entrainment and the effect of changing rheological parameters are developed. It is argued that such bedform initiation occurs due to anisotropic rheological variations within the mobile debris setting up a 'feedback effect". Such conditions are thought to be found most likely at the Lower interface of a fast moving ice mass possibly typical of an ice stream. In using empirical analyses of mobile debris conditions a limited set of relationships between subglacial meltwater flux rates, basal ice velocity, debris porosity and bed width are established with reference to mobile debris thicknesses. Using this relationship, a set of possible parameter values that would allow bed formation to be achieved are presented. The impact of bed formation under these conditions upon possible sedimentological facies and deformation structures is postulated. The wider effect of "M"-bed conditions on subglacial sedimentology is introduced and the need to investigate subglacial hydraulic and bed conditions under past glaciations from the evidence of their glacial sediments and landforms emphasised.

Modern and Past Glacial Environments, 2002

Modern and Past Glacial Environments, 2002