| Previous Site | Next Site |
Earth Science Conservation Review
| Rathfriland | Down |
| Site number: | 572 | ||
| ESCC: | EO | ||
| Locality Type: | Inland exposure | Status: | ASSI |
| Grid Reference: | J20453545 Centroid | ||
| Google maps: | 54.25375,-6.15265 | ||
| County: | Down | Council area: | Armagh City, Banbridge & Craigavon Borough Council |
| Period: | Devonian | ||
| Stages: | Lower Devonian | ||
| Lithostrat: | Newry Igneous Complex | ||
| Site Description | |
|---|---|
| Highlights: | |
This site consists of unfoliated granodiorite belonging to the central part of the northeast pluton of the late Caledonian Newry Igneous Complex. The granodiorites are more acidic in composition than those at the margins of the pluton indicating "normal zoning". | |
| Introduction: | |
This site is an area of natural outcrops located approximately 2km north of Rathfriland. The land can be accessed from a C class road that connects the B7 (Ballyroney Road) and B25 (Banbridge Road). The rocks at this site are located towards the centre of the northeast pluton of the Newry Igneous Complex. On the first edition of the Newry (Sheet 60), one-inch to the mile geological map (Geological Survey of Ireland, 1876) the rocks in this area were mapped as granite. Subsequent thin section petrology and classification by Reynolds (1934; 1936) showed the rocks to be granodiorites, i.e. rich in quartz, plagioclase feldspar, alkali feldspar, biotite mica with some hornblende. The classification and terminology of Reynolds still stands when these rocks are classified in modern schemes such as Streckeisen's (1976). Systematic sampling, thin section petrology and geochemistry (Grant, 1961; Meighan and Neeson, 1979; Neeson, 1984) have revealed compositional zoning within the granodiorite plutons. At the margins of the northeast and southwest plutons the rocks are more basic than at the centres of the intrusions, This zoning pattern has been described as "normal zoning". The opposite is seen in the middle pluton, which is described as displaying "reverse zoning". Meighan & Neeson (1979) published a Rb-Sr age of 399±3Ma for granodiorite in the northeast pluton. Field relations indicate that this pluton was the first of the three major bodies that together account for most of the Newry Igneous Complex. | |
| Description: | |
Medium to coarse-grained granodiorite forming part of the central part of the northeast pluton is exposed at this site. In thin section, this rock was found top be rich in plagioclase and alkali feldspar, quartz, hornblende and biotite (Meighan pers. comm., 1999). The granodiorite at this site is free of the foliation and alignment of biotite commonly seen close to the margins of the pluton and attributed by (Murphy, 1987) to the intrusion and shouldering aside of country rock during diapiric emplacement. | |
| Importance: | |
The Rathfriland site is of national importance offering access to high quality exposure of unfoliated granodiorite that forms the central part of the northeast pluton. A compositional difference between granodiorites at this site and those close to the northeast pluton margin indicates normal zoning of the intrusion. Such zoning could be evidence of fractional crystallization of magma after emplacement. | |
| Interpretation: | |
Compositional differences between granodiorite at this site and that close to the margin of the northeast pluton indicates "normal zoning" of the intrusion. Such zoning could be evidence of fractional crystallisation of magma taking place after emplacement. An alternative explanation is that several injections of magma might have been involved in the formation of the northeast pluton. A similar model could pertain to the formation of each of the plutons that together constitute the Newry Igneous Complex (Meighan and Neeson, 1979). The absence of foliation within the granodiorites at this site is consistent with the geological setting, i.e. the site is at the centre of the pluton, away from marginal deformation caused by the regional deformation (Cameron, 1981) and the shouldering aside of the country rock caused by the diapiric emplacement of the magma (Murphy, 1987). | |
| Conclusions: | |
The Rathfriland site contains exposure of unfoliated granodiorite which is typical of the central portion of the northeast pluton of the Newry Igneous Complex. Compositional differences between granodiorites at this site and those close to the margin of the northeast pluton indicate "normal zoning". Such zoning could be evidence that the magma evolved through a fractionation process after emplacement. | |
| 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 573 - Gransha Key Site 574 - Aughnagon Quarry Key Site 575 - Goraghwood 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 | |
|---|---|
| Rocks: | Granodiorite |
| Structures: | Caledonian, pluton, normal zoning |
| Access | |
|---|---|
| Approach: | The land can be accessed from a C class road that connects the B7 (Ballyroney Road) and B25 (Banbridge Road). |
| Management: | |
The site occupies an area of farmland that is currently used for crops and grazing of livestock. Landowner permission should be sought before entering the site. Exposures are of a limited size and it would be advisable to restrict hammering 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. | |
| Threats: | Sampling should be restricted due to limited size of outcrop. |
| Uses | |
| Uses: | Farmland: arable and grazing. |
| Map(s): | GEOLOGICAL SURVEY OF IRELAND, 1876. 1:63,360 Geological Sheet 60 (Newry). 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. Rathfriland, County Down, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=572. Accessed on 2026-11-08. |
| Previous Site | Next Site |