The BGS Lexicon of Named Rock Units — Result Details

Crathie Point Calc-Silicate Member

Computer Code: CRPT Preferred Map Code: CrPt
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Thin-bedded flaggy calc-silicate, calcareous semipelite and impure metacarbonate rock, with beds of metalimestone; bands of distinctive schistose garnet-muscovite-biotite semipelite in upper part. Calcareous psammite beds sparse but more abundant near top.
Definition of Lower Boundary: Base of lowest limestone bed in sequence of flaggy semipelites and psammites of Cairnfield Calcareous Flag Formation.
Definition of Upper Boundary: Transitional decrease in frequency of limestone beds and increase in proportion of calc-psammites relative to calc-semipelites.
Thickness: c.200 to 250m on coast section, but locally tightly folded; not measurable inland.
Geographical Limits: From coast at Crathie Point [NJ 5475 6725 - 5495 6715], as far inland as Broom [NJ 543 662], south of which it cannot be distinguished from the rest of the Cairnfield Calcareous Flag Formation.
Parent Unit: Cairnfield Calcareous Flag Formation (CCFL)
Previous Name(s): Middle Portion Of Crathie Point Calcareous Group (-3333)
Crathie Point Calcareous Flag Member (-2118)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  On coast at Crathie Point. 
Reference(s):
Stephenson, D and Gould, D , 1995. British Regional Geology: the Grampian Highlands (4th edition). (London: HMSO for the British Geological Survey), 67-68. 
Read, H H, 1923. Geology of the country around Banff, Huntly and Turriff, Lower Banffshire and north-west Aberdeenshire. Memoir of the Geological Survey, Scotland Sheets 86 and 96 (Scotland). 
Harris, A L, Haselock, P J, Kennedy, M J and Mendum, J R, 1994. The Dalradian Supergroup in Scotland, Shetland and Ireland. 33-53 in Gibbons, W E and Harris, A L (editors). A revised correlation of Precambrian rocks in the British Isles. Special Report of the Geological Society, London, No.22. 
Stephenson, D, et al. 1993. Stratigraphy and correlation of the Dalradian rocks of the East Grampian Project area. British Geological Survey Technical Report WA/93/91. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S096