Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America
The drumlin sediments at Chimney Bluffs, New York appear to represent a block-inmatrix style glacial melange. This melange comprises sand stringers, lenses and intraclasts juxtaposed in an apparently massive diamicton. Thin section examination of these glacigenic deposits has revealed microstructure...
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ftbrockuniv:oai:dr.library.brocku.ca:10464/2045 2024-06-09T07:46:51+00:00 Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America Dreger, Derek Leslie. Department of Earth Sciences 2009-07-09T18:42:47Z http://hdl.handle.net/10464/2045 eng eng Brock University http://hdl.handle.net/10464/2045 Drumlins--New York (State)--Chimney Bluffs Sediments (Geology)--New York (State)--Chimney Bluffs Electronic Thesis or Dissertation 2009 ftbrockuniv 2024-05-16T06:42:42Z The drumlin sediments at Chimney Bluffs, New York appear to represent a block-inmatrix style glacial melange. This melange comprises sand stringers, lenses and intraclasts juxtaposed in an apparently massive diamicton. Thin section examination of these glacigenic deposits has revealed microstructures indicative of autokinetic subglacial defonnation which are consistent with a deformable bed origin for the diamicton. These features include banding and. necking of matrix grains, oriented plasma fabrics and the formation of pressure shadows at the long axis ends of elongate clasts. Preservation of primary stratification within the sand intraclasts appears to suggest that these features were pre-existing up-ice deposits that were frozen, entrained, then deposited as part of a defonning till layer beneath an advancing ice sheet. Multi-directional micro-shearing within the sand blocks is thought to reflect the frozen nature of the sand units in such a high strain environment. It is also contended that dewatering of the sediment pile leading to the eventual immobilisation of the defonning till layer was responsible for opening sub-horizontal fissures within the diamicton. These features were subsequently infilled with mass flow poorly sorted sands and silts which were subjected to ductile defonnation during the waning stages of an actively deforming till layer. Microstructures indicative of the dewatering processes in the sand units include patches of fine-grained particles within a coarser-grained matrix and the presence of concentrated zones of translocated clays. However, these units were probably confined within an impermeable diamicton casing that prevented massive pore water influxes from the deforming till layer~ Hence, these microstructures probably reflect localised dewatering of the sand intraclasts. A layered subglacial shear zone model is proposed for the various features exhibited by the drumlin sediments. The complexity of these structures is explained in terms of ii superposing deformation styles in ... Thesis Ice Sheet Brock University Digital Repository |
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Open Polar |
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Brock University Digital Repository |
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ftbrockuniv |
language |
English |
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Drumlins--New York (State)--Chimney Bluffs Sediments (Geology)--New York (State)--Chimney Bluffs |
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Drumlins--New York (State)--Chimney Bluffs Sediments (Geology)--New York (State)--Chimney Bluffs Dreger, Derek Leslie. Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America |
topic_facet |
Drumlins--New York (State)--Chimney Bluffs Sediments (Geology)--New York (State)--Chimney Bluffs |
description |
The drumlin sediments at Chimney Bluffs, New York appear to represent a block-inmatrix style glacial melange. This melange comprises sand stringers, lenses and intraclasts juxtaposed in an apparently massive diamicton. Thin section examination of these glacigenic deposits has revealed microstructures indicative of autokinetic subglacial defonnation which are consistent with a deformable bed origin for the diamicton. These features include banding and. necking of matrix grains, oriented plasma fabrics and the formation of pressure shadows at the long axis ends of elongate clasts. Preservation of primary stratification within the sand intraclasts appears to suggest that these features were pre-existing up-ice deposits that were frozen, entrained, then deposited as part of a defonning till layer beneath an advancing ice sheet. Multi-directional micro-shearing within the sand blocks is thought to reflect the frozen nature of the sand units in such a high strain environment. It is also contended that dewatering of the sediment pile leading to the eventual immobilisation of the defonning till layer was responsible for opening sub-horizontal fissures within the diamicton. These features were subsequently infilled with mass flow poorly sorted sands and silts which were subjected to ductile defonnation during the waning stages of an actively deforming till layer. Microstructures indicative of the dewatering processes in the sand units include patches of fine-grained particles within a coarser-grained matrix and the presence of concentrated zones of translocated clays. However, these units were probably confined within an impermeable diamicton casing that prevented massive pore water influxes from the deforming till layer~ Hence, these microstructures probably reflect localised dewatering of the sand intraclasts. A layered subglacial shear zone model is proposed for the various features exhibited by the drumlin sediments. The complexity of these structures is explained in terms of ii superposing deformation styles in ... |
author2 |
Department of Earth Sciences |
format |
Thesis |
author |
Dreger, Derek Leslie. |
author_facet |
Dreger, Derek Leslie. |
author_sort |
Dreger, Derek Leslie. |
title |
Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America |
title_short |
Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America |
title_full |
Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America |
title_fullStr |
Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America |
title_full_unstemmed |
Sedimentology and micromorphology of drumlin sediments at Chimney Bluffs State Park, New York, United States of America |
title_sort |
sedimentology and micromorphology of drumlin sediments at chimney bluffs state park, new york, united states of america |
publisher |
Brock University |
publishDate |
2009 |
url |
http://hdl.handle.net/10464/2045 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_relation |
http://hdl.handle.net/10464/2045 |
_version_ |
1801376845723074560 |