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Earth Science Conservation Review
| Goraghwood Quarry | Armagh |
| Site number: | 575 | ||
| ESCC: | ED | ||
| Locality Type: | Quarry (disused) | Status: | ASSI |
| Grid Reference: | J06553195 Centroid | ||
| Google maps: | 54.2254,-6.36706 | ||
| County: | Armagh | Council area: | Newry, Mourne & Down District Council |
| Period: | Devonian, Silurian | ||
| Stages: | Lower Devonian | ||
| Lithostrat: | Newry Igneous Complex | ||
| Site Description | |
|---|---|
| Highlights: | |
Outcrops in Goraghwood Quarry can be used to demonstrate the relationship between bands of contact metamorphosed, calcareous Silurian country rock and a variety of granodioritic rock types in the middle pluton of the Newry Igneous Complex. | |
| Introduction: | |
Goraghwood Quarry lies approximately 1km south-southeast of Jerrettspass, on the A27 Tandragee Road. Access can be gained via a track that leads to the now derelict Goraghwood railway station. Landowner permission will be needed to gain access. Geologically, the site is located at the northern margin of the middle pluton of the Newry Igneous Complex. The first edition of the Castleblayney (Sheet 59) one-inch to one mile geological map (Geological Survey of Ireland, 1875) indicates porphyritic granite in contact with bands of metamorphosed Silurian country rock that trend southwest to northeast. A basic dyke of Palaeogene age (Tertiary) is also shown at Goraghwood. The memoir accompanying the map (Egan, 1877) provides detailed descriptions of the rocks at this location. Country rock is described as 'micaceous and quartzitic schist' occurring as steeply dipping bands within porphyritic granite (locally called 'blue granite') and the more usual granite (locally called 'white granite'). Egan noted that bedding was undeformed, and that its attitude corresponded closely to that outside the pluton; this he saw as clear evidence against an intrusive origin for the rocks, leading him to favour a transformation of country rock by extreme metamorphism. The rocks in Goraghwood Quarry formed the basis of an investigation by Reynolds (1943), who identified and described three varieties of hornfels (diopside-hornfels, cordierite-biotite-hornfels and plagioclase hornfels) in contact with biotite granodiorite and dark porphyritic granodiorite. Reynolds' was in agreement with earlier workers, supporting the theory that the granodiorites had formed from the country rock by a process termed granitization (Reynolds, 1946). Systematic sampling, thin section petrology and geochemistry (Grant, 1961; Meighan and Neeson, 1979 Neeson, 1984) subsequently revealed composition zoning within the plutons in the Newry Igneous Complex. Granodiorite at the margin of the middle pluton is more acid than at the centre of the intrusion. As such, the pluton is described as displaying "reverse zoning". The opposite pattern is seen in the northeast and southwest plutons, which are described as having "normal zoning". | |
| Description: | |
At Goraghwood, most of the critical rock types and relationships can be observed in the section directly west of the derelict railway station building, in the southern third of the quarry. An unquarried, steeply inclined 20m wide 'screen' of metamorphosed country rock (Reynolds, 1943) can be observed. The rock is banded light green and dark grey and is composed of fine-grained diopside- and biotite-hornfels respectively (Meighan, pers. comm., 1999). The hornfels displays original sedimentary bedding which dips approximately 70° to the northwest. This bedding more or less corresponds to bedding seen outside of the middle pluton. Granodiorite of variable composition surrounds the hornfelsed screen and include dark-coloured porphyritic granodiorite and lighter biotite-granodiorite varieties. Granodiorite veins and pods, of variable composition, are found enclosed within the country rock and main granodiorite bodies. The contacts between metamorphosed country rock and the various varieties of granodiorite are generally sharp with no sign of gradational or chilled margins. | |
| Importance: | |
Goraghwood Quarry is a site of national importance offering access to exposures which show the relationships between contact metamorphosed Silurian country rock and various granodiorites of the middle pluton of the Newry Igneous Complex. At this site, it is possible to demonstrate the variety, and relative timing of intrusion, of igneous rock types that comprise the middle pluton. | |
| Interpretation: | |
Exposure within the southern part of Goraghwood Quarry reveals a screen of Silurian country rock enclosed and contact metamorphosed by granodiorites of the middle pluton. The range of hornfels observed (diopside- and biotite-hornfels) is related to compositional and lithological variations in the original sediment. The main variation in the sedimentary protolith was probably between greywacke and calcareous shale beds. The occurrence of sharp contacts between the metamorphosed country rock and various granodioritic rock types is not consistent with the early non-intrusive granitization theories of Reynolds (1946). It is however consistent with the magmatic intrusive origin for the complex proposed by Meighan and Neeson (1979). The variety of granodiorite observed is evidence that several injections of magma were involved during the formation of the middle pluton; this is a feature regarded as common to the formation of each of the plutons that together constitute the Newry Igneous Complex (Meighan and Neeson, 1979). | |
| Conclusions: | |
Goraghwood Quarry contains exposure of the relationships between contact metamorphosed Silurian country rock and various granodiorites of the middle pluton of the Newry Igneous Complex. The site demonstrates the variety, and relative timing of intrusion, of igneous rock types in the middle pluton of the Newry Igneous Complex. | |
| Notes: | |
For information and references on other sites within the Newry Igneous Complex see the following sites: Key Site 568 - Ardglass, Co Down Key Site 569 - Slieve Croob Key Site 570 - Shannaghan Hill Key Site 571 - Ballymagreehan Quarry Key Site 572 - Rathfriland Key Site 573 - Gransha Key Site 574 - Aughnagon Quarry Key Site 576 - Newry By-pass Key Site 577 - Cam Lough Quarry Key Site 578 - Kearney Point Key Site 579 - Ballyhalbert Pier For general information and references on the Caledonian Igneous Complexes of N. Ireland, and for directions to other regional sites, see the following site: Key Site 595 - Introduction to the Caledonian Igneous Complexes of N. Ireland | |
| Keywords | |
|---|---|
| Minerals: | Biotite, Cordierite, Diopside |
| Rocks: | Granodiorite, Greywacke, Hornfels, Pegmatite, Calcareous shale |
| Structures: | Caledonian, pluton |
| Relations: | Intrusion, Contact metamorphism |
| Access | |
|---|---|
| Approach: | Access can be gained via a track that leads to the now derelict Goraghwood railway station. |
| Management: | |
Goraghwood Quarry is disused and somewhat overgrown. Rock surfaces are slippery and overlooked by steep quarry faces. Great care will be needed to reach the quarry, as the main Belfast to Dublin railway line must be crossed. Landowner permission will be needed to gain access. Outcrop is abundant and there is no need to restrict hammering or sampling at this site. The rocks of the Newry Igneous complex are considered to be prospective for a number of minerals including base metals and gold. Licensed mineral exploration and production has previously been carried out in Counties Armagh and Down. The area which includes this site is likely to attract further exploration activity. | |
| Map(s): | GEOLOGICAL SURVEY OF IRELAND, 1875. 1:63,360 Geological Sheet 59 (Castleblayney). (Dublin, Ordnance Survey for Geological Survey of Ireland). | ||
| Record type: | ESCR report | ||
| Entered by: | E M Porter | ||
| Last updated: | 03 MAR 2001 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Goraghwood Quarry, County Armagh, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=575. Accessed on 2026-11-06. |
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