Scotland Chalk nomenclature (Scottish Chalk Province) - Inner Hebrides Group: Coire Riabhach Phosphatic Formation: Difference between revisions
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=====Name===== | |||
Name | |||
The name first appears in Mortimore et al. (2001) and is substantially unrecognised in previous descriptions. | The name first appears in Mortimore et al. (2001) and is substantially unrecognised in previous descriptions. | ||
=====''Type section''===== | |||
''Type section'' | |||
Stream section on the west bank of Coire Riabhach [NM 697 564] on the northeast flank of Beinn Iadain. | Stream section on the west bank of Coire Riabhach [NM 697 564] on the northeast flank of Beinn Iadain. | ||
=====''Primary Reference Section''===== | |||
''Primary Reference Section'' | |||
As above | As above | ||
=====Formal subdivision===== | |||
Formal subdivision | |||
None | None | ||
=====Lithology===== | |||
Lithology | |||
Up to five beds of glauconitic sand with phosphate nodules and fossil casts. | Up to five beds of glauconitic sand with phosphate nodules and fossil casts. | ||
=====Definition of upper boundary===== | |||
Definition of upper boundary | |||
Unconformable (or a non-sequence at an erosion surface) with the overlying Gribun Chalk Formation. | Unconformable (or a non-sequence at an erosion surface) with the overlying Gribun Chalk Formation. | ||
=====''Definition of lower boundary ''===== | |||
''Definition of lower boundary '' | |||
Conformable (or a non-sequence at an erosion surface) with the underlying Lochaline White Sandstone Formation. | Conformable (or a non-sequence at an erosion surface) with the underlying Lochaline White Sandstone Formation. | ||
=====''Thickness''===== | |||
''Thickness'' | |||
Usually less than one metre. | Usually less than one metre. | ||
=====Distribution===== | |||
Distribution | |||
Limited to the Beinn Iadain area. | Limited to the Beinn Iadain area. | ||
=====''Previous names''===== | |||
''Previous names'' | |||
None | None | ||
=====Parent===== | |||
Parent | |||
Inner Hebrides Group. | Inner Hebrides Group. | ||
=====Age and biostratigraphy===== | |||
Age and biostratigraphy | |||
Upper Cretaceous, Coniacian to Santonian in Mortimore et al., (2001).'' '' | Upper Cretaceous, Coniacian to Santonian in Mortimore et al., (2001).'' '' | ||
=====''References''===== | |||
''References'' | |||
Mortimore, Wood and Gallois (2001). (In this volume a number of the correlations in the earlier works are adjusted and the dating of the sequence refined. The term Coire Riabhach Phosphatic Formation appears first in this volume as one of the adjustments to the terminology and correlation of the sequence proposed by Braley, 1990). | Mortimore, Wood and Gallois (2001). (In this volume a number of the correlations in the earlier works are adjusted and the dating of the sequence refined. The term Coire Riabhach Phosphatic Formation appears first in this volume as one of the adjustments to the terminology and correlation of the sequence proposed by Braley, 1990). | ||
NOTE: - Because of its relative thinness it is questionable as to whether this bed is a ‘mappable’ unit and as such worthy of formational status, however it is prominent in sections logged in Morvern and may prove the correlative of the basal unit of the Gribun Chalk Formation as mapped on Mull where glauconite is seen in the sequences associated with erosional surfaces. It may also be a key link with the Northern Ireland succession where Mortimore et al. correlate it with the Cloghfin Sponge Formation at the base of the Ulster White Limestone Group. | NOTE: - Because of its relative thinness it is questionable as to whether this bed is a ‘mappable’ unit and as such worthy of formational status, however it is prominent in sections logged in Morvern and may prove the correlative of the basal unit of the Gribun Chalk Formation as mapped on Mull where glauconite is seen in the sequences associated with erosional surfaces. It may also be a key link with the Northern Ireland succession where Mortimore et al. correlate it with the Cloghfin Sponge Formation at the base of the Ulster White Limestone Group. | ||
Latest revision as of 13:06, 11 June 2014
Name
The name first appears in Mortimore et al. (2001) and is substantially unrecognised in previous descriptions.
Type section
Stream section on the west bank of Coire Riabhach [NM 697 564] on the northeast flank of Beinn Iadain.
Primary Reference Section
As above
Formal subdivision
None
Lithology
Up to five beds of glauconitic sand with phosphate nodules and fossil casts.
Definition of upper boundary
Unconformable (or a non-sequence at an erosion surface) with the overlying Gribun Chalk Formation.
Definition of lower boundary
Conformable (or a non-sequence at an erosion surface) with the underlying Lochaline White Sandstone Formation.
Thickness
Usually less than one metre.
Distribution
Limited to the Beinn Iadain area.
Previous names
None
Parent
Inner Hebrides Group.
Age and biostratigraphy
Upper Cretaceous, Coniacian to Santonian in Mortimore et al., (2001).
References
Mortimore, Wood and Gallois (2001). (In this volume a number of the correlations in the earlier works are adjusted and the dating of the sequence refined. The term Coire Riabhach Phosphatic Formation appears first in this volume as one of the adjustments to the terminology and correlation of the sequence proposed by Braley, 1990).
NOTE: - Because of its relative thinness it is questionable as to whether this bed is a ‘mappable’ unit and as such worthy of formational status, however it is prominent in sections logged in Morvern and may prove the correlative of the basal unit of the Gribun Chalk Formation as mapped on Mull where glauconite is seen in the sequences associated with erosional surfaces. It may also be a key link with the Northern Ireland succession where Mortimore et al. correlate it with the Cloghfin Sponge Formation at the base of the Ulster White Limestone Group.