| Computer Code: |
MOSSA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Miocene Epoch (NM)
— Miocene Epoch (NM) |
| Lithological Description: |
The Muckle Ossa Sandstone is characteristically green to dark green, occasionally black, fine-to-coarse grained, poorly sorted, generally friable but partly calcite cemented, muddy, glauconitic and bioclastic, with sporadic gravel clasts. The bioclasts include molluscs, bivalves and corals. Subordinate interbedded lithologies include dark green mudstones and sandy siltstones (e.g. 77/07), sandy limestones (e.g. 77/09) and lignites (e.g. 202/8-1). |
| Definition of Lower Boundary: |
The lower boundary is the composite erosion surface of the shelf unconformity which truncates Palaeogene and older strata and was, at least in part, formed in association with the latest Oligocene/earliest Miocene unconformity. |
| Definition of Upper Boundary: |
The upper boundary is everywhere marked by an angular unconformity. This is a composite boundary, marked by the intra-Neogene unconformity over most of the shelf, but where this is absent it is truncated by the glacial unconformity. |
| Thickness: |
The Muckle Ossa Sandstone is preserved as an eroded, fairly uniform, sheet deposit, locally up to 150 m thick. |
| Geographical Limits: |
The Muckle Ossa Sandstone is restricted to the West Shetland Shelf. |
| Parent Unit: |
Lower Nordland Unit (NORDL)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
BGS borehole 77/07: 47.5-110.2 m below sea bed (Stoker, 1999). |
| Reference Section |
BGS borehole 77/09: 61.5-92.3 m below sea bed (Stoker, 1999). |
| Reference Section |
BGS borehole 90/03: 66.28-96.0 m below sea bed (Stoker, 1999). |
| Reference(s): |
| Stoker, M S. 1999. Stratigraphic nomenclature of the UK North West Margin. 3. Mid- to Late Cenozoic Stratigraphy. BGS, Nottingham. |
| Deegan, C E and Scull, B J. 1977. A standard lithostratigraphic nomenclature for the Central and Northern North Sea. Report of the Institute of Geological Sciences, 77/25; NPD Bulletin No.1. |
| Isaksen, D and Tonstad, K. 1989. A revised Cretaceous and Tertiary lithostratigraphic nomenclature for the Norwegian North Sea. NPD-Bulletin No.5 |
| Evans, D, Chesher, J A, Deegan, C E, and Fanntn, N G T. 1981. The offshore geology of Scotland in relation to the 1GS shallow drilling programme. Report of the Institute of Geological Sciences, No. 81/12. |
| Gregersen, U, Michelsen, O, and Sorensen, J C. 1997. Stratigraphy and facies distribution of the Utsira Formation and the Pliocene sequences in the northern North Sea. Marine and Petroleum Geology, 14, 893-914. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
