Mullineux, S., Sparks, R.S.J., Murphy, M.D., MacNiocaill, C., Barfod, D. , Njorka, J. and Schumacher, J.C. (2020) Columnar-jointed bentonite below a Doleritic Sill, Tideswell Dale, Derbyshire, UK: formation during prograde contact metamorphism. Geological Magazine, 157(7), pp. 1181-1198. (doi: 10.1017/S0016756819001535)
Full text not currently available from Enlighten.
Abstract
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 µm) 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.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Barfod, Dr Dan |
| Authors: | Mullineux, S., Sparks, R.S.J., Murphy, M.D., MacNiocaill, C., Barfod, D., Njorka, J., and Schumacher, J.C. |
| College/School: | College of Science and Engineering > Scottish Universities Environmental Research Centre |
| Journal Name: | Geological Magazine |
| Publisher: | Cambridge University Press |
| ISSN: | 0016-7568 |
| ISSN (Online): | 1469-5081 |
| Published Online: | 12 February 2020 |
University Staff: Request a correction | Enlighten Editors: Update this record
Deposit and Record Details
Deposit and Record Details