| Computer Code: |
DOTH |
Preferred Map Code: |
DOTH |
| Status Code: |
Full |
| Age range: |
Cryogenian Period (AC)
— Cryogenian Period (AC) |
| Lithological Description: |
Lower part comprises a calcareous semipelite to calcsilicate rock about 5m thick, locally tremolite-bearing. The calcareous unit is succeeded by alternating layers (approximately 10 to 30cm thick) of muscovite-rich semipelite, psammite and thin quartzite. Grossular-bearing amphibolite schist and coarser plagioclase-amphibolite are locally developed within the formation. In the area around Beinn a'Chuirn, quartzite is more dominant in the uppermost parts of the Beinn an Dothaidh Formation; this unit is recogniZed as the Allt a'Chuirn Quartzite Member. |
| Definition of Lower Boundary: |
Sharp change massive garnetiferous semipelite of the Coire Daingean Semipelite Formation to the alternating muscovite-rich semipelite, psammite and quartzite of the Beinn an Dothaidh Formation. A calcareous semipelite of calcsilicate-rock (c.5m thick) may be present locally at the base of the Beinn and Dothaidh Formation. |
| Definition of Upper Boundary: |
Change to the more uniform garnetiferous semipelite rocks of the Beinn Dorain Semipelite Formation. In the area around Beinn a'Chuirn, quartzite is more dominant in the uppermost parts of the Beinn an Dothaidh Formation; this unit is recognised as the Allt a'Chuirn Quartzite Member. |
| Thickness: |
The formation is estimated to be about 180 to 200m thick on Beinn a'Chaisteil but is typically apparently thickened by the effects of fold duplication. |
| Geographical Limits: |
This formation is recognized across the northeastern parts of Sheet 46W west and north of Loch Lyon and also west of the Bridge Balgie Fault in upper Glen Lyon to Loch an Daimh in the western part of Sheet 46E, and southwestern part of Sheet 54E. |
| Parent Unit: |
Lochaber Subgroup (DALO)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Beinn an Dothaidh, especially the western, eastern and northern slopes, but also Beinn Achaladair, west of Coire Daingean and section on Beinn a'Chaisteil. Details will be included in Sheet Description for Sheet 46W (Crainlarich). Presently in draft BGS internal report: Leslie et al., Progress Report on the Geology of the Tyndrum area, 2003. 1:50k Sheet 46W (Crianlarich). |
| Reference(s): |
| Will be included in Sheet Description for Sheet 46W (Crianlarich) and 46E (Killin). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
S046
|
