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IV.—The Geology of Slieve Gullion, Foughill and Carrickcarnan: An Actualistic Interpretation of a Tertiary Gabbro-granophyre Complex

Published online by Cambridge University Press:  06 July 2012

Doris L. Reynolds
Doris L. Reynolds
Affiliation:
Grant Institute of Geology, University of Edinburgh.
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Synopsis:

An interpretation of the Tertiary rocks of the area, which are shown to be denudation relics of a gigantic volcano, is found by following the actualistic principle, that is by interpreting the unknown with reference to the known or actual. “Actualistic”, i.e. with reference to actual causes—commonly used by continental geologists—is chosen in preference to “uniformitarian” since the latter stands in contradistinction to “catastrophic”, and is not, therefore, altogether appropriate to some of the more violent aspects of volcanic activity. Gabbros and granophyres, hitherto thought to be plutonic intrusions emplaced within Caledonian granodiorite, are shown to be highly metamorphosed basaltic and rhyolitic lava-flows, agglomerates and tuffs, together with some gabbro sills. These rocks form a layered series which is almost horizontal at Slieve Gullion, and dips at various angles at Foughill and Carrickcarnan. A Tertiary ring-dyke of granophyre and felsite encircles the layered rocks and outlines a caldera within which the basaltic lavas (including pillow-lavas) of Slieve Gullion accumulated. During the formation of a later caldera these lavas became inset within the underlying Caledonian granodiorite. The acid layers of Slieve Gullion represent rhyolites, incandescent tuff-flows, and agglomerates, the materials of which were derived from the Caledonian granodiorite. The time of eruption of these acid rocks is correlatable with periods of caldera formation.

The layered series is dissected by arcuate faults, and contacts previously thought to be intrusive are now demonstrated to be faulted. Transgressive granophyres follow the faults and form intrusion-breccias and net-vein systems with the layered series. Evidence is presented for concluding that these granophyres originated as glassy acid tuffisite—an intrusive pyroclastic rock (Cloos, 1941)—derived from the basement Caledonian granodiorite, and emplaced by rising gas-streams. That the gas sometimes had a temperature high enough to fuse basalt is witnessed by the fact that the basaltic rocks commonly become exceedingly fine grained where they adjoin transgressive granophyre. Such fine-grained edges are cross-cutting to the layers and cannot therefore be interpreted as normal chilled edges. Hybrid rocks, e.g. marscoite, are associated with the transgressive granophyres. They are shown to represent mechanical mixtures of acid tuffisite, carried upwards by rising gas-streams, with fragmented (tuffisitised) and partially fused basic material derived from the walls of the channels. The transgressive granophyres and associated hybrids are related in origin to incandescent tuff-flows, and are regarded as marking the routes by which such flows reached the surface.

The metamorphism of the basaltic flows, and the transformation of the acid layers and transgressive acid tuffisites to granophyre, were probably accomplished during the pneumatolytic and hydrothermal phase of volcanic activity. Transformation of the acid rocks to granophyre involved introduction of K and Si, and removal of Na, Al, Fe, Ca, Ti, P and Mn. Similar chemical interchanges transformed basaltic rocks at Foughill and Carrickcarnan to quartz-dolerites. The subtracted materials have been located in small-scale basic fronts margining granophyres; within masses of gabbro that sank within gas-tuff streams from higher levels; and in dispersed form within the basic rocks of Slieve Gullion.

Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 62 , Issue 1 , 1952 , pp. 85 - 143
Copyright
Copyright © Royal Society of Edinburgh 1952

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References

References to Literature

Anderson, T., and Flett, J. S., 1903. “Report on the Eruptions of the Soufrière, in St Vincent, in 1902, and on a Visit to Montagne Pelée, in Martinique. Part I”, Phil. Trans. Roy. Soc. London, A, cc, 353–553.CrossRefGoogle Scholar
Backlund, H. G., 1937. “Sur quelques Roches Éruptives de la Série Basaltique de la Côte Orientale du Groenland”, Compt. rendus Acad. Sciences, CCIV, 1745–1746.Google Scholar
Backlund, H. G., 1941. “Die ältesten Baueinheiten von Fennoskandia”, Mitt. Nat. Gesell. Schaffhausen, XVI, No. 4, 31–73.Google Scholar
Backlund, H. G., 1943. “Einblick in das geologische Geschehen des Präkambriums”, Geol. Rundschau, XXXIV, 79–148.CrossRefGoogle Scholar
Bailey, E. B., Thomas, H. H., and others, 1924. “Tertiary and post-Tertiary Geology of Mull, Loch Aline, and Oban”, Mem. Geol. Surv. Scotland.Google Scholar
Bonney, T. G., 1907. “On the Supposed Kimberlite Magma and Eclogite Concretions”, Trans. Geol. Soc. S. Africa, X, 95–100.Google Scholar
Bowen, N. L., 1928. The Evolution of the Igneous Rocks, Princeton Univ. Press.Google Scholar
Bowen, N. L., and Tuttle, O. F., 1949. “The System MgO—SiO2—H2O”, Bull. Geol. Soc. Amer., LX, 439–460.CrossRefGoogle Scholar
Charlesworth, J. K., and Hartley, J. J., 1948. “The Geology of Eastern Ireland”, Internat. Geol. Congress, 18th Session, Gt. Britain, 1948.Google Scholar
Cloos, H., 1941. “Bau und Tätigkeit von Tuffschloten. Untersuchungen an dem Schwäbischen vulkan”, Geol. Rundsch., XXXII, 709–800.Google Scholar
Clough, C. T., Maufe, H. B., and Bailey, E. B., 1909. “The Cauldron-subsidence of Glen Coe, and the Associated Igneous Phenomena”, Quart. Journ. Geol. Soc. London, LXV, 611–678.Google Scholar
Egan, F. W., 1877. Explanatory Memoir to accompany Sheet 59 of the Maps of the Geological Survey of Ireland, Mem. Geol. Surv.Google Scholar
Escher, B. G., 1927. “Vesuvius, the Tengger Mountains and the Problem of Calderas”, Leidsche Geolog. Mededeelingen, II, 51–88.Google Scholar
Escher, B. G., 1929. “On the Formation of Calderas”, Leidsche Geolog. Mededeelingen, III, 183–219.Google Scholar
Fenner, C. N., 1920. “The Katmai Region, Alaska, and the Great Eruption of 1912”, Journ. Geol., XXVIII, 569–606.CrossRefGoogle Scholar
Fenner, C. N., 1923. “The Origin and Mode of Emplacement of the Great Tuff Deposit of the Valley of Ten Thousand Smokes”, Nat. Geog. Soc., Katmai Series, No. 1, 1–74.Google Scholar
Fenner, C. N., 1926. “The Katmai Magmatic Province”, Journ. Geol., XXXIV, 673–772.CrossRefGoogle Scholar
Fenner, C. N., 1933. “Pneumatolytic Processes in the Formation of Minerals and Ores”. In “Ore-Deposits of the Western States”, Amer. Inst. Mining and Metallurgical Engineers, 58–106.Google Scholar
Fenner, C. N., 1936. “Bore-hole Investigations in Yellowstone Park”, Journ. Geol., XLIV, 225–315.CrossRefGoogle Scholar
Fenner, C. N., 1937 a. “Tuffs and Other Volcanic Deposits of Katmai and Yellowstone Park”, Trans. Amer. Geophys. Union, Eighteenth Annual Meeting, 236–239.CrossRefGoogle Scholar
Fenner, C. N., 1937 b. “A View of Magmatic Differentiation”, Journ. Geol., XLV, 158–166.CrossRefGoogle Scholar
Fenner, C. N., 1938. “Contact Relations between Rhyolite and Basalt on Gardiner River, Yellowstone Park”, Bull. Geol. Soc. Amer., XLIX, 1441–1483.CrossRefGoogle Scholar
Fenner, C. N., 1948. “Incandescent Tuff Flows in Southern Peru”, Bull. Geol. Soc. Amer., LIX, 879–893.CrossRefGoogle Scholar
Garrels, R. M., Dreyer, R. M., and Howland, A. L., 1949. “Diffusion of Ions through Intergranular Spaces in Water-saturated Rocks”, Bull. Geol. Soc. Amer., LX, 1809–1828.Google Scholar
Greig, J. W., Merwin, H. E., and Shepherd, E. S., 1933. “Notes on the Volatile Transport of Silica”, Amer. Journ. Sci., XXV, 61–73.CrossRefGoogle Scholar
Harker, A., 1904. “The Tertiary Igneous Rocks of Skye”, Mem. Geol. Surv. Scotland.CrossRefGoogle Scholar
Hawkes, L., and Harwood, H. F., 1932. “On the Changed Composition of an Anorthoclase-bearing Rock-glass”, Min. Mag., XXIII, 163–174.Google Scholar
Holmes, A., 1936 a. “A Record of New Analyses of Tertiary Igneous Rocks (Antrim and Staffa)”, Proc. Roy. Irish Acad., XLIII, B8, 89–94.Google Scholar
Holmes, A., 1936 b. “The Idea of Contrasted Differentiation”, Geol. Mag., LXXIII, 228–238.Google Scholar
Jaggar, T. A., 1949. “Steam Blast Volcanic Eruptions. A Study of Mount Pelée in Martinique as Type Volcano”, Fourth Special Report of the Hawaiian Volcano Observatory. U.S. Geol. Surv. and Hawaiian Volcano Research Assoc.Google Scholar
Lacroix, A., 1893. “Les Enclaves des Roches Volcaniques, Part III”, Ann. Acad. Mâcon., X.Google Scholar
Lacroix, A., 1907. Produits Silicatés de l'Éruption du Vésuve, Paris.Google Scholar
Macgregor, A. G., 1931. “Clouded Felspars and Thermal Metamorphism”, Min. Mag., XXII, 524–538.Google Scholar
Macgregor, A. G., 1938. “The Volcanic History and Petrology of Montserrat, with Observations on Mt Pelé in Martinique”, Phil. Trans. Roy. Soc. London, CCXXIX, 1–90.Google Scholar
M'Lintock, W. F. P., 1915. “On the Zeolites and Associated Minerals from the Tertiary Lavas around Ben More, Mull”, Trans. Roy. Soc. Edin., LI, 1–33.Google Scholar
Michel-Levy, A., and Wyart, J., 1939. “Synthèse de l'Orthose et de l'Albite par Pneumatolyse à l'Aide d'Explosifs Brisants”, Comptes rendus Acad. Sci., CCVIII, 293–294.Google Scholar
Michel-Levy, A., and Wyart, J., 1939. “Synthèse du Quartz, par Pneumatolyse, à l'Aide d'Explosifs Brisants. Formation d'Inclusions Liquides à Libelle Mobile”, Comptes rendus Acad. Sci., CCVIII, 1594–1595.Google Scholar
Nolan, J., 1877. Explanatory Memoir to accompany Sheet 70 of the Maps of the Geological Survey of Ireland, Mem. Geol. Surv.Google Scholar
Nolan, J., 1879. “On the Ancient Volcanic District of Slieve Gullion”, Geol. Mag., dec. 2, V, 445–449.Google Scholar
Perret, F. A., 1924. “The Vesuvius Eruption of 1906. Study of a Volcanic Cycle”, Carnegie Inst. Washington, No. 339.Google Scholar
Reynolds, Doris L., 1937. “Contact Phenomena Indicating a Tertiary Age for the Gabbros of the Slieve Gullion District”, Proc. Geol. Assoc., XLVIII, 247–275.CrossRefGoogle Scholar
Reynolds, Doris L., 1941. “A Gabbro-Granodiorite Contact in the Slieve Gullion Area, and its Bearing on Tertiary Petrogenesis”, Quart. Journ. Geol. Soc. London, XCVII, 1–38.Google Scholar
Reynolds, Doris L., 1946. “The Sequence of Geochemical Changes leading to Granitisation”, Quart. Journ. Geol. Soc. London, CII, 389–446.CrossRefGoogle Scholar
Reynolds, Doris L., 1947. “The Association of Basic ‘Fronts’ with Granitisation”, Science Progress, XXXV, 205–219.Google Scholar
Reynolds, Doris L., 1950. “The Transformation of Caledonian Granodiorite to Tertiary Granophyre on Slieve Gullion, Co. Armagh N. Ireland”, Internat. Geol. Congress, 18th Session, Gt. Britain, 1948, Part III, 20–30.Google Scholar
Richey, J. E., 1927. “The Structural Relations of the Mourne Granites”, Quart. Journ. Geol. Soc. London, LXXXIII, 653–688.CrossRefGoogle Scholar
Richey, J. E., 1931–1932. “Tertiary Ring Structures in Britain”, Trans. Geol. Soc. Glasgow, XIX, 42–140.Google Scholar
Richey, J. E., 1932. “The Tertiary Ring Complex of Slieve Gullion (Ireland)”, Quart. Journ. Geol. Soc. London, LXXXVIII, 776–849.CrossRefGoogle Scholar
Richey, J. E., 1935. “Further Evidence Concerning the Age of the Gabbros of the Slieve Gullion District”, Proc. Geol. Assoc., XLVI, 487–492.CrossRefGoogle Scholar
Richey, J. E., Thomas, H. H., and others, 1930. “The Geology of Ardnamurchan, North-West Mull and Coll”, Mem. Geol. Surv. Scotland.Google Scholar
Rust, W., 1937. “Preliminary Notes on Explosive Volcanism in Southeastern Missouri”, Journ. Geol., XLV, 48–75.CrossRefGoogle Scholar
Traill, W. A., 1878. Explanatory Memoir to accompany Part of Sheets 60 and 71 of the Maps of the Geological Survey of Ireland. Mem. Geol. Surv.Google Scholar
Tyrrell, G. W., 1928. “The Geology of Arran”, Mem. Geol. Surv. Scotland.Google Scholar
Walton, M. S., and O'Sullivan, R. B., 1950. “The Intrusive Mechanics of a Clastic Dike”, Amer. Journ. Sci., CCXLVIII, 1–21.Google Scholar
Wilcox, R. E., 1944. “The Rhyolite-Basalt Complex on Gardiner River, Yellowstone Park, Wyoming”, Bull. Geol. Soc. Amer., LL, 1047–1080.Google Scholar
Wilson, G., 1950. “An Experimental Synthesis of Quartz, Albite, and Analcite”, Geol. Mag., LXXXVII, 41–44.Google Scholar
Zies, E. G., 1924. “The Fumarolic Incrustations in the Valley of Ten Thousand Smokes”, Nat. Geog. Soc., Katmai Series, 1, No. 3, 157–179.Google Scholar
Zies, E. G., 1929. “The Fumarolic Incrustations and their Bearing on Ore Deposition”, Nat. Geog. Soc., Katmai Series, 1, No. 4, 1–61.Google Scholar