Northern Ireland Chalk nomenclature (Ulster Cretaceous Province) - Hibernian Greensands Group: Kilcoan Sands Formation

Name

The Kilcoan Sands Member was first used in Griffith and Wilson (1982). The term is upgraded to formation status herein.

Type section

The old cutting to the old Kilcoan Quarry [J 4610 9850] west Island Magee.

Primary Reference Section

Numerous localities on the Larne, Antrim, Carrickfergus and Belfast sheet areas (see Griffith and Wilson (1982), Page 48, Figure 16A).

Formal subdivision

None

Lithology

Pale green glauconitic sands thought largely to be derived from the Collinwell Sands Formation. Three conspicuous Inoceramus bands divide the succession into three unequal parts.

Definition of lower boundary

Disconformable at an erosion surface above the mid-Hibernian Greensands ‘unconformity’. Rests on each of the older formations in the group and overlaps onto pre-Cretaceous strata over the most positive structural highs.

Definition of upper boundary

Disconformable at an erosion surface beneath various younger members of the Ulster White Limestone Group.

Thickness

Up to 7.3m at Kilcoan.

Distribution

Fully developed in the Island Magee area and within the East Antrim Basin and Southern Uplands area. Elsewhere in Northern Ireland the formation may be represented in the condensed successions of the undivided Hibernian Greensands Group.

Previous names

Part of the Chloritic Sands and Sandstones of Tate (1865) and Hume (1897); part of the Upper Glauconitic Beds of Hancock (1961); The Upper Hibernian Greensands of Reid (1971); Senonian Greensands of Manning, Robbie and Wilson (1970).

Kilcoan Sands Member.

Parent

Hibernian Greensands Group.

Age and biostratigraphy

Coniacian to Santonian. Micraster cortestudinarium to Micraster coranguinum zones.

References

Fletcher (1967); Griffith and Wilson (1982).