Carboniferous of County Armagh, Northern Ireland - Revision history

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	The Wilson’s Bridge Limestone Formation in Rock Road quarry [H 871 434] shows evidence of reworking of soft sediment and benthic faunas as a 2 m bed of conglomerate composed of the colonial corals Lithostrotion and ''Michelinia'' and ''Siphonophyllia benburbensis''. Limestone intraclast conglomerate and lenticular sandstone are exposed in a lane section at Annacramph [H 886 494]. Most limestone quarries in the area are developed in the Loughgall Limestone Formation using the distinctive pale grey to creamy white, coarse-grained bioclastic and oolitic grainstone.		The Wilson’s Bridge Limestone Formation in Rock Road quarry [H 871 434] shows evidence of reworking of soft sediment and benthic faunas as a 2 m bed of conglomerate composed of the colonial corals Lithostrotion and ''Michelinia'' and ''Siphonophyllia benburbensis''. Limestone intraclast conglomerate and lenticular sandstone are exposed in a lane section at Annacramph [H 886 494]. Most limestone quarries in the area are developed in the Loughgall Limestone Formation using the distinctive pale grey to creamy white, coarse-grained bioclastic and oolitic grainstone.

	The quarry section [H 878 498] in the Carganamuck Limestone Formation [[Media:P947819.jpg\| (P947819)]] contains Brigantian corals including ''Actinocyathus floriformis'' and ''Diphyphyllum lateseptatum'' <ref name = "Somerville2001"/> and the brachiopod ''Gigantoproductus'' ~~[[File:P948074.jpg\| thumbnail\| (P948074) Fossils 11–15]].~~		The quarry section [H 878 498] in the Carganamuck Limestone Formation [[Media:P947819.jpg\| (P947819)]] contains Brigantian corals including ''Actinocyathus floriformis'' and ''Diphyphyllum lateseptatum'' <ref name = "Somerville2001"/> and the brachiopod ''Gigantoproductus''


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	[[Category:Northern Ireland]]		[[Category:The geology of Northern Ireland]]

Dbk at 11:03, 25 September 2017

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← Older revision		Revision as of 12:03, 25 September 2017
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	The Wilson’s Bridge Limestone Formation in Rock Road quarry [H 871 434] shows evidence of reworking of soft sediment and benthic faunas as a 2 m bed of conglomerate composed of the colonial corals Lithostrotion and ''Michelinia'' and ''Siphonophyllia benburbensis''. Limestone intraclast conglomerate and lenticular sandstone are exposed in a lane section at Annacramph [H 886 494]. Most limestone quarries in the area are developed in the Loughgall Limestone Formation using the distinctive pale grey to creamy white, coarse-grained bioclastic and oolitic grainstone.		The Wilson’s Bridge Limestone Formation in Rock Road quarry [H 871 434] shows evidence of reworking of soft sediment and benthic faunas as a 2 m bed of conglomerate composed of the colonial corals Lithostrotion and ''Michelinia'' and ''Siphonophyllia benburbensis''. Limestone intraclast conglomerate and lenticular sandstone are exposed in a lane section at Annacramph [H 886 494]. Most limestone quarries in the area are developed in the Loughgall Limestone Formation using the distinctive pale grey to creamy white, coarse-grained bioclastic and oolitic grainstone.

	The quarry section [H 878 498] in the Carganamuck Limestone Formation [[Media:P947819.jpg\| (P947819)]] contains Brigantian corals including ''Actinocyathus floriformis'' and ''Diphyphyllum lateseptatum'' <ref name = "Somerville2001"/> and the brachiopod ''Gigantoproductus'' [[File:P948074.jpg\| (P948074) Fossils 11–15]].		The quarry section [H 878 498] in the Carganamuck Limestone Formation [[Media:P947819.jpg\| (P947819)]] contains Brigantian corals including ''Actinocyathus floriformis'' and ''Diphyphyllum lateseptatum'' <ref name = "Somerville2001"/> and the brachiopod ''Gigantoproductus'' [[File:P948074.jpg\| thumbnail\| (P948074) Fossils 11–15]].

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{{nibrg}}
W I Mitchell

== Introduction ==
[[File:P947815.jpg|thumbnail|Geological map of Northern Ireland showing the Carboniferous outcrop. (P947815)]]

[[File:P947927.jpg|thumbnail|Distribution and classification of Carboniferous rocks in Northern Ireland. (P947927)]]

[[File:P947819.jpg|thumbnail|Litho-, bio- and chronostratigraphy of the Carboniferous rocks in the Armagh area. (P947819)]]

[[File:P948074.jpg|thumbnail|Fossils 11–15 Early Carboniferous (Brigantian) fossils from the Carganamuck Limestone Formation (Armagh Group) in Co. Armagh: (P948074) ]]
In the Carboniferous outcrop between Co. Fermanagh and north Co. Armagh [[Media:P947815.jpg| (P947815)]] the component formations of the Tyrone Group [[Media:P947927.jpg| (P947927)]] maintain their lithological integrity. However, in the rest of Co. Armagh the Carboniferous succession is thinner and is divided into two groups. With the exception of the Killuney Conglomerate and Carganamuck Limestone formations [[Media:P947819.jpg| (P947819)]] details are available from the 359m deep Wilson’s Bridge borehole <ref name = "Somerville2001">Somerville, I D, Strogen, P, Mitchell, W I, Higgs, K, and Somerville, H E A. Stratigraphy of Dinantian rocks in a borehole from Co. Armagh, N. Ireland. ''Irish Journal of Earth Sciences'', 19 (2001), 51–78.</ref>.

=== Tyrone Group ===
The unconformity with Ordovician rocks is exposed in the Killuney stream [H 896 461]. Late Tournaisian strata at the base of the Tyrone Group were deposited before and during a marine transgression and comprise the Killuney Conglomerate, Retreat Siltstone and Ballynahone Micrite formations [[Media:P947819.jpg| (P947819)]]. Two significant biostratigraphical events occur in the latter formation. The appearance of the miospore ''Lycospora pusilla'' marks the early Chadian and the foraminiferan ''Eoparastaffella'' simplex marks the base of the late Chadian and the Tournaisian-Viséan series boundary. The base of the TS Biozone in the Milford Mills Formation coincides with the appearance of the miospore ''Knoxisporites stephanephorus'' [[Media:P947819.jpg| (P947819)]]. The Oulart Villa Limestone Formation at Oulart Villa [H 897 469] contains the coral ''Dorlodotia pseudovermiculare'' and early Arundian foraminifera at the base, with ''D.'' cf. ''briarti'' and ''Siphonodendron'' ''martini'' and mid- to late Arundian foraminifera at the top. The base of the Drumman More Sandstone Formation is probably Holkerian, based on the presence of Lithostrotion corals and the foraminifera ''Paraarchaediscus'' at ''concavus'' stage. Near the top of the Formation the miospore ''Perotrilites tesselatus'' indicates the TC Biozone and a Holkerian–early Asbian age.

=== Armagh Group ===
The Armagh Group consists almost exclusively of marine, shallow water limestones with palaeokarst surfaces and reddish brown clay palaeosols. Although their use as building stone has declined it is still quarried for aggregate between Loughgall and Armagh [[Media:P947815.jpg| (P947815)]]. It is represented by three formations of late Asbian to Brigantian age [[Media:P947819.jpg| (P947819)]].

The Wilson’s Bridge Limestone Formation in Rock Road quarry [H 871 434] shows evidence of reworking of soft sediment and benthic faunas as a 2 m bed of conglomerate composed of the colonial corals Lithostrotion and ''Michelinia'' and ''Siphonophyllia benburbensis''. Limestone intraclast conglomerate and lenticular sandstone are exposed in a lane section at Annacramph [H 886 494]. Most limestone quarries in the area are developed in the Loughgall Limestone Formation using the distinctive pale grey to creamy white, coarse-grained bioclastic and oolitic grainstone.

The quarry section [H 878 498] in the Carganamuck Limestone Formation [[Media:P947819.jpg| (P947819)]] contains Brigantian corals including ''Actinocyathus floriformis'' and ''Diphyphyllum lateseptatum'' <ref name = "Somerville2001"/> and the brachiopod ''Gigantoproductus'' [[File:P948074.jpg| (P948074) Fossils 11–15]].

==References==
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[[Category:Northern Ireland]]