| Computer Code: |
MALP |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Tonian Period (AT)
— Tonian Period (AT) |
| Lithological Description: |
Siliceous to micaceous psammite, with minor semipelite. For lower parts see Arnisdale Psammite Member (MAAP) and Rubha Ruadh Semipelite Member (MARRS). The upper half of the formation comprises coarse to gritty, thick-bedded (0.5 - 4 m), arkosic psammite. Sedimentary structures are obvious and abundant, including channels with stacked planar and trough cross-bedding with cosets (0.3 -1 m). Abundant soft-sediment deformation structures, locally affecting up to 4 m thick. Towards the top more thinly bedded and finer grained, with an increase in semipelitic beds towards its upper contact with the Morar Schists Formation. |
| Definition of Lower Boundary: |
Conformably upon the Basal Pelite Formation (MABP) or unconformable typically of the Western Glenelg Gneiss (WGG); unconformity normally highly sheared. |
| Definition of Upper Boundary: |
Conformably overlain by the Morar Schists Formation (MAMS). Relatively sharp boundary with incoming of pelitic beds. |
| Thickness: |
c. 2000 - 3000 m (estimate, strongly deformed in places). |
| Geographical Limits: |
NW Highlands: Ardnamurchan, Morar, Knoydart, Kintail. |
| Parent Unit: |
Morar Group (MORR)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Partial Type Section |
Type section for upper half of Fm: NW of Ladhar Bheinn: Meall Gruamach to Mullach Li [NG 806 079 - NG 819 063]. |
| Reference(s): |
| Ramsay, J.G. and Spring, J., 1962. Moine stratigraphy in the Western Highlands of Scotland. Proceedings of the Geological Association, 73: 295-326. |
| Krabbendam, M. 2021. A stratigraphic framework for the early Neoproterozoic successions of the Northern Highlands of Scotland. UK Stratigraphic Framework Series. British Geological Survey Open Report, OR/21/072. 86pp. |
| Krabbendam, M, Leslie, A, and Goodenough, K. 2014. Structure and stratigraphy of the Morar Group in Knoydart, NW Highlands: implications for the history of the Moine Nappe and stratigraphic links between the Moine and Torridonian successions. Scottish Journal of Geology, Vol. 50, 125-142. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
S071
S072
S061
S061
S062
|
