Bringelly Shale
| Bringelly Shale | |
|---|---|
| Stratigraphic range: Middle Triassic | |
 | |
| Type | Geological formation |
| Unit of | Wiannamatta group |
| Overlies | Hawkesbury sandstone |
| Thickness | up to 60 metres (200 ft) |
| Location | |
| Location | Western Sydney |
| Region | Cumberland Plain |
| Country | Australia |
| Type section | |
| Named for | Bringelly |
Bringelly Shale is a component of the Wianamatta group of sedimentary rocks in the Sydney Basin of eastern Australia. Formed in the Triassic Period, it has an extensive outcrop in the western parts of Sydney. The shale has its greatest geographical extent at Bringelly, near the suburb of Liverpool.
Lithology
[edit]The shale is the topmost layer of sedimentary rock laid down by a river delta over the older Hawkesbury sandstone in the Triassic Period.[1]
It is similar to Ashfield Shale in that both have low porosities, though differing in having a greater amount of calcareous, graywacke-type, lithic sandstone bands and lenses, carbonaceous claystone, siltstone, laminite, but would lack sideritic mudstone bands that Ashfield Shale has. Bringelly Shale has lumpy clay minerals, and it swells and decays rapidly on submergence in water and is generally less durable.[2]
Description
[edit]The average thickness is around 60 metres.[3] It was deposited in a swampy alluvial plain with winding streams that formed sporadic beds of sandstone. The shale is dark when unweathered just like the Ashfield Shale. The shale is usually a typical olive-green colour when weathered. Alloyed coal bands and lenses and iron oxide concretions have been observed in the shale. The shale is quarried in many western suburbs of Sydney for brick and miscellaneous ceramic manufacture.[4]
See also
[edit]
References
[edit]- ^ Wianamatta shale Dictionary of Sydney
- ^ William, E and Airey, DW. A Review of the Engineering Properties of the Wianamatta Group Shales [online]. In: Vitharana, Nihal Dhamsiri (Editor); Colman, Randal (Editor). Proceedings 8th Australia New Zealand Conference on Geomechanics: Consolidating Knowledge. Barton, ACT: Australian Geomechanics Society, 1999: 641-647. Availability: <https://search.informit.com.au/documentSummary;dn=736896154066797;res=IELENG> ISBN 1864450029.
- ^ Lovering, J. F. "Bringelly Shale" (PDF). STRATIGRAPHY OF' THE WIANAMATTA GROUP. Australian Museum. Retrieved August 23, 2012.
- ^ Chris Herbert & Robin Helby (1980). A Guide to the Sydney basin (1st ed.). Maitland, NSW: Geological Survey of NSW. p. 582. ISBN 978-0-7240-1250-3.