Columnar-jointed bentonite below a doleritic sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphism
Columnar-jointed tuffs (bentonites) are located below the Lower Carboniferous Tideswell Dale Sill, Derbyshire, in an abandoned quarry. There are three zones of prismatic joints, columnar joints (∼60 cm thick and mean column width of 4.1 cm) and massive, conchoidally fractured rock sequentially from...
| Main Authors: | , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
Cambridge University Press
2020
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| _version_ | 1797109737441984512 |
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| author | Mullineux, S Sparks, RSJ Murphy, MD MacNiocaill, C Barfod, D Njorka, J Schumacher, JC |
| author_facet | Mullineux, S Sparks, RSJ Murphy, MD MacNiocaill, C Barfod, D Njorka, J Schumacher, JC |
| author_sort | Mullineux, S |
| collection | OXFORD |
| description | Columnar-jointed tuffs (bentonites) are located below the Lower Carboniferous Tideswell Dale Sill, Derbyshire, in an abandoned quarry. There are three zones of prismatic joints, columnar joints (∼60 cm thick and mean column width of 4.1 cm) and massive, conchoidally fractured rock sequentially from the dolerite contact downwards. The rocks are very fine-grained (1-10 m) and consist mainly of sanidine, interlayered illite/smectite, and hematite, with minor quartz, apatite, montmorillonite, anatase and detrital minerals. High K2O and Fe2O3, low Na2O and low MgO are interpreted as due to alteration of felsic volcanic ash. The bentonite was contact-metamorphosed by the sill to temperatures of c. 300 °C. The progression of fracture geometries, thermal considerations and application of theories of column formation indicate that columns formed downwards away from the sill, due to prograde contact metamorphism of the originally clay-rich bentonite. The formation of columnar fracture networks by shrinkage due to igneous heating may have implications for the effectiveness of bentonite as a barrier for disposal of high-level radioactive waste. Regional dimensions include documenting widespread felsic explosive volcanism and inferring a Triassic oxidation event from palaeomagnetic data. |
| first_indexed | 2024-03-07T07:45:41Z |
| format | Journal article |
| id | oxford-uuid:92f4f631-7511-42c9-a14a-1c499113edfb |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:45:41Z |
| publishDate | 2020 |
| publisher | Cambridge University Press |
| record_format | dspace |
| spelling | oxford-uuid:92f4f631-7511-42c9-a14a-1c499113edfb2023-06-08T08:59:34ZColumnar-jointed bentonite below a doleritic sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphismJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:92f4f631-7511-42c9-a14a-1c499113edfbEnglishSymplectic ElementsCambridge University Press2020Mullineux, SSparks, RSJMurphy, MDMacNiocaill, CBarfod, DNjorka, JSchumacher, JCColumnar-jointed tuffs (bentonites) are located below the Lower Carboniferous Tideswell Dale Sill, Derbyshire, in an abandoned quarry. There are three zones of prismatic joints, columnar joints (∼60 cm thick and mean column width of 4.1 cm) and massive, conchoidally fractured rock sequentially from the dolerite contact downwards. The rocks are very fine-grained (1-10 m) and consist mainly of sanidine, interlayered illite/smectite, and hematite, with minor quartz, apatite, montmorillonite, anatase and detrital minerals. High K2O and Fe2O3, low Na2O and low MgO are interpreted as due to alteration of felsic volcanic ash. The bentonite was contact-metamorphosed by the sill to temperatures of c. 300 °C. The progression of fracture geometries, thermal considerations and application of theories of column formation indicate that columns formed downwards away from the sill, due to prograde contact metamorphism of the originally clay-rich bentonite. The formation of columnar fracture networks by shrinkage due to igneous heating may have implications for the effectiveness of bentonite as a barrier for disposal of high-level radioactive waste. Regional dimensions include documenting widespread felsic explosive volcanism and inferring a Triassic oxidation event from palaeomagnetic data. |
| spellingShingle | Mullineux, S Sparks, RSJ Murphy, MD MacNiocaill, C Barfod, D Njorka, J Schumacher, JC Columnar-jointed bentonite below a doleritic sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphism |
| title | Columnar-jointed bentonite below a doleritic sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphism |
| title_full | Columnar-jointed bentonite below a doleritic sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphism |
| title_fullStr | Columnar-jointed bentonite below a doleritic sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphism |
| title_full_unstemmed | Columnar-jointed bentonite below a doleritic sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphism |
| title_short | Columnar-jointed bentonite below a doleritic sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphism |
| title_sort | columnar jointed bentonite below a doleritic sill tideswell dale derbyshire uk formation during prograde contact metamorphism |
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