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VIII.—The Petrology of the Layered Basic Rocks of the Carlingford Complex, Co. Louth

Published online by Cambridge University Press:  30 May 2017

M. J. Le Bas
M. J. Le Bas*
Affiliation:
Department of Mineralogy and Petrology, University of Cambridge
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Synopsis

The principal basic components of the Tertiary Carlingford complex are believed to have formed through the differentiation of magma of a high-alumina basaltic type. These rocks, which were once thought to be in the form of a ring-dyke, are shown to occur as a floored and multi-layered intrusion. Four major layers have been recognized. Within each, differentiation through crystal fractions settling under the influence of gravity is believed to have been the chief factor producing chemical variation. The effect of this process is seen in the compositional and modal variations of the gabbroic rocks and their constituent minerals. The variations from bottom to top of each layer correspond to a decreasing temperature of crystallization with height. At the bottoms are gabbros enriched in olivine. At the tops, the gabbros are rich in plagioclase. Throughout the layers, the plagioclases are transitional between the high and low (temperature) structural states. The resemblance of these rocks to other layered intrusions (e.g. Rhum, Bushveld, etc.) is taken as proof of the magmatic origin of the Carlingford layered basic rocks.

The base of the lowest layer is in contact with Silurian sediments and Tertiary basalts. The sediments have been intensely metasomatized with reciprocal contamination of the gabbro immediately above. Greater extremes of metasomatism and mobilization are seen in the sedimentary xenoliths which occur within the gabbros. At the base of the topmost layer of gabbro, a horizontal screen of highly metasomatized Silurian sediments separates that gabbro from the one below.

Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 64 , Issue 8: 1958-1959 The Petrology of the Layered Basic Rocks of the Carlingford Complex, Co. Louth , 1960 , pp. 169 - 200
Copyright
Copyright © Royal Society of Edinburgh 1960

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References

References to Literature

Agrell, S. O., and Langley, J. M., 1958. “The Dolerite Plug at Tievebulliagh, near Cushendall, Co. Antrim”, Proc. Roy. Irish Acad., 59, B, 93-127.Google Scholar
Bailey, E. B., and McCallien, W. J., 1956. “Composite Minor Intrusions, and the Slieve Gullion Complex, Ireland”, L'pool and Manchr. Geol. J., 1, 466–501.Google Scholar
Bailey, E. B., et at., 1924. “Tertiary and Post-Tertiary Geology of Mull, Loch Aline, and Oban”, Mem. Geol. Surv. U.K. Google Scholar
Bowen, N. L., 1928. The Evolution of the Igneous Rocks. Princeton University Press.Google Scholar
Bowen, N. L., and Schairer, J. P., 1935. “The System MgO-FeO-SiO2 ”, Amer. J. Sci., 29, 151–217.Google Scholar
Brown, G. M., 1956. “The Layered Ultrabasic Rocks of Rhum, Inner Hebrides”, Philos. Trans., B, 240, 1–53.Google Scholar
Brown, G. M., 1957. “Pyroxenes from the Early and Middle Stages of Fractionation of the Skaergaard Intrusion, East Greenland”, Min. Mag., 31, 511–543.Google Scholar
Buddington, A. F., Fahey, J., and Vlisidis, A., 1955. “Thermometric and Petrogenetic Significance of Titaniferous Magnetite”, Amer. J. Sci., 253, 497–532.Google Scholar
Cook, A. H., and Murphy, T., 1952. “Gravity Survey of Ireland, North of the line Sligo–Dundalk”, Institute of Advanced Studies, School of Cosmic Physics, Dublin, Geophys. Mem. Dublin, 2, (4), 1–36.Google Scholar
Friedman, G. M., 1957. “Structure and Petrology of the Caribou Lake Intrusive Body, Ontario, Canada”, Bull. Geol. Soc. Amer., 68, 1531–1564.CrossRefGoogle Scholar
Griffith, R., 1840. Presidential Address. J. Geol. Soc. Dublin, 1843 (2), 95–130.Google Scholar
Grout, F. F., 1918. “The Lopolith; an Igneous Form Exemplified by the Duluth Gabbro”, Amer. J. Sci., 46, 516–522.Google Scholar
Grout, F. F., 1933. “Contact Metamorphism of the Slates of Minnesota by Granite and Gabbro Magmas”, Bull. Geol. Soc. Amer., 44, 989–1040.Google Scholar
Hamilton, C. W., 1839. “Observations and Sections made in the District lying between the Mourne and Dublin Mountains”, J. Geol. Soc. Dublin, 1843 (2), 51–69.Google Scholar
Harker, A., 1904. “Tertiary Igneous Rocks of Skye”, Mem. Geol. Surv. U.K. CrossRefGoogle Scholar
Harry, W. T., 1952. “Basic Hornfels at a Gabbro Contact near Carlingford, Eire”, Geol. Mag., 89, 411–416.CrossRefGoogle Scholar
Harry, W. T., 1954. “The Clinopyroxene-hornblende Equilibrium in Thermal Metamorphism: Some Data from Carlingford, Eire”, Geol. Mag., 91, 79–85.CrossRefGoogle Scholar
Haughton, S., 1856. “Experimental Researches on the Granites of Ireland”, Quart. J. Geol. Soc. Lond., 12, 171–202.Google Scholar
Haughton, S., 1858. “Experimental Researches on the Granites of Ireland”, Quart. J. Geol. Soc. Lond., 14, 300–305.CrossRefGoogle Scholar
Haughton, S., 1876. “On the Trap Dykes that penetrate the Granites, Metamorphic Slates, and Carboniferous Limestones, of the District of Mourne, in the North-east of Ireland”, J. Roy. Geol. Soc. Ire., 4, 91–104.Google Scholar
Henry, N. F. M., 1942. “Lamellar Structure in Orthopyroxenes”, Min. Mag., 26, 179–189.Google Scholar
Hess, H. H., 1939. “Extreme Fractional Crystallization of a Basaltic Magma: The Stillwater Igneous Complex”, Trans. Amer. Geophys. Un., 430–432.Google Scholar
Hess, H. H., 1949. “Chemical Composition and Optical Properties of common Clino-pyroxenes”, Amer. Min., 34, 621–666.Google Scholar
Hess, H. H., 1952. “Orthopyroxenes of the Bushveld Type, Ion Substitutions and Changes in Unit Cell Dimensions”, Amer. J. Sci., Bowen Vol., 173-188.Google Scholar
Hull, E., 1875. “On the Microscopic Structure of a Fragment of ‘Baked’ or Indurated Slate, from the Lower Silurian Rocks, Claremont Hill, near Dundalk”, J. Roy. Geol. Soc. Ire., 4, 85–88.Google Scholar
Lasaulx, A. Von, 1878. “Petrographische Skizzen aus Irland. III. Olivingabbro von den Carlingford Mts., nördlich von Dundalk”, Miner. Petrgr. Mitt., 1, 426–433.Google Scholar
Le Bas, M. J., 1955. “Magmatic and Amygdaloidal Plagioclases”, Geol. Mag., 92, 291–296.Google Scholar
Lombaard, B. V., 1934. “On the Differentiation and Relationships of the Rocks of the Bushveld Complex”, Trans. Geol. Soc. S. Afr., 37, 5–52.Google Scholar
Muir, I. D., 1951. “The Clinopyroxenes of the Sksergaard Intrusion, Eastern Greenland”, Min. Mag., 26, 690–714.Google Scholar
Muir, I. D., and Tilley, C. E., 1957. “Contributions to the Petrology of Hawaiian Basalts. I. The Picrite-basalts of Kilauea”, Amer. J. Sci., 255, 241–253.CrossRefGoogle Scholar
Murray, R. J., 1954. “The Clino-pyroxenes of the Garbh Eilean Sill, Shiant Isles”, Geol. Mag., 91, 17–31.Google Scholar
Nicholls, G. D., 1955. “The Mineralogy of Rock Magnetism”, Advanc. Phys., 4, 113–190.Google Scholar
Nockolds, S. R., 1935. “Contributions to the Petrology of Barnavave, Carlingford, I.F.S. I. The Junction Hybrids”, Geol. Mag., 72, 289–315.CrossRefGoogle Scholar
Nockolds, S. R., 1938. “Contributions to the Petrology of Barnavave, Carlingford, I.F.S. III. On Some Hybrids from the E. and S.E. Slopes of Barnavave Mountain”, Geol. Mag., 75, 469–479.CrossRefGoogle Scholar
Pettijohn, F. J., 1957. Sedimentary Rocks. New York.Google Scholar
Poldervaart, A., 1950. “Correlation of Physical Properties and Chemical Composition in the Plagioclase, Olivine and Ortho-pyroxene Series”, Amer. Min., 35, 1067–1079.Google Scholar
Poldervaart, A., and Hess, H. H., 1951. “Pyroxenes in the Crystallization of Basaltic Magma”, J. Geol., 59, 472–489.CrossRefGoogle Scholar
Ramberg, H., and De Vorge, G., 1951. “The Distribution of Fe+2 and Mg+2 in coexisting Olivines and Pyroxenes”, J. Geol., 59, 193–210.CrossRefGoogle Scholar
Reynolds, D. L., 1951. “The Geology of Slieve Gullion, Foughill and Carrickcarnan: an Actualistic Interpretation of a Tertiary Gabbro-granophyre Complex”, Trans. Roy. Soc. Edin., 62, 85–143.Google Scholar
Richey, J. E., 1932a. “Tertiary Ring Structures in Britain”, Trans. Geol. Soc. Glasg., 19, 42–140.Google Scholar
Richey, J. E., 1932b. “The Tertiary Ring Complex of Slieve Gullion (Ireland)”, Quart. J. Geol. Soc. Lond., 88, 776–849.CrossRefGoogle Scholar
Richey, J. E., 1937. “Apatite in Tertiary Igneous Rocks”, Summ. Progr. Geol. Surv. Lond., 1935, 46–52.Google Scholar
Richey, J. E., 1958. “Feldspathic Types of Basaltic Rocks”. Dolerite, a Symposium, Univ. of Tasmania, 63–69.Google Scholar
Richey, J. E., and Thomas, H. H., 1930. “Geology of Ardnamurchan, North-west Mull and Coll”, Mem. Geol. Surv. U.K. Google Scholar
ROSE, G., 1863. “Beschribung und Eintheilung der Meteoriten”, Abh. Preuss. Akad. Wiss., 26–161.Google Scholar
Sadashivatah, M. S., 1950. “Olivine-bearing and other Basic Hornfelses around the Insch Igneous Mass, Aberdeenshire”, Geol. Mag., 87, 121–130.CrossRefGoogle Scholar
Scholtz, D. L., 1936. “The Magmatic Nickeliferous Ore Deposits of East Griqualand and Pondoland”, Trans. Geol. Soc. S. Afr., 39, 81–210.Google Scholar
Shapiro, L., and Brannock, W. W., 1956. “Rapid Analysis of Silicate Rocks”, Bull. U.S. Geol. Surv., 1036-C.Google Scholar
Shaw, D. M., 1956. “Geochemistry of Pelitic Rocks. III. Major Elements and General Geochemistry”, Bull. Geol. Soc. Amer., 67, 919–934.Google Scholar
Simpson, E. S. W., 1954. “The Okonjeje Igneous Complex, South-west Africa”, Trans. Geol. Soc. S. Afr., 57, 125–172.Google Scholar
Smith, J. R., 1957. “Optical Properties of Heated Plagioclases”, Yearb. Carneg. Instn., 56, 216–217.Google Scholar
Smith, J. V., and Gay, P., 1958. “The Powder Patterns and Lattice Parameters of Plagioclase Felspars, II”, Min. Mag., 31, 744–762.Google Scholar
Sollas, W. J., 1894. “On the Volcanic District of Carlingford and Slieve Gullion. I. On the Relation of the Granite to the Gabbro of Barnavave, Carlingford”, Trans. Roy. Irish Acad., 30, 477–512.Google Scholar
Tilley, C. E., 1950. “Some Aspects of Magmatic Evolution”, Quart. J. Geol. Soc. Lond., 106, 37–61.Google Scholar
Traill, W. A., 1878. “Explanatory Memoir to accompany part of Sheets 60 and 71”, Mem. Geol. Surv. Ireland. Google Scholar
Vincent, E. A., and Phillips, R., 1954. “Iron-titanium Oxide Minerals in Layered Gabbros of the Skærgaard Intrusion, East Greenland”, Geochim. Cosmoch. Acta, 6, 1–26.CrossRefGoogle Scholar
Wager, L. R., 1953. “Layered Intrusions”, Medd. Dansk. Geol. Foren., 12, 335–349.Google Scholar
Wager, L. R., and Bailey, E. B., 1953. “Basic Magma chilled against Acid Magma”, Nature, Lond., 172, 68.Google Scholar
Wager, L. R., and Deer, W. A., 1939. “Petrology of the Skærgaard Intrusion, Kangerdlugssuaq, East Greenland”, Medd. Grønland, 105, 1–352.Google Scholar
Walker, F., 1940. “Differentiation of the Palisade Diabase, New Jersey”, Bull. Geol. Soc. Amer., 60, 1059–1106.Google Scholar
Walker, F., 1957. “Ophitic Texture and Basaltic Crystallization”, J. Geol., 65, 1–14.Google Scholar
Walker, F., nnd Poldervaart, A., 1949. “Karroo Dolerites of the Union of South Africa”, Bull. Geol. Soc. Amer., 60, 591–706.Google Scholar
Wells, M. K., 1951. “Sedimentary Inclusions in the Hypersthene-gabbro, Ardnamurchan, Argyllshire”, Min. Mag., 29, 715–736.Google Scholar
Wells, M. K., 1954. “The Structure and Petrology of the Hypersthene-gabbro Intrusion, Ardnamurchan, Argyllshire”, Quart. J. Geol. Soc. Lond., 109, 367–398.CrossRefGoogle Scholar
Wilkinson, J. F. G., 1957a. “The Clinopyroxenes of a Differentiated Teschenite Sill near Gunnedah, New South Wales”, Geol. Mag., 94, 123–134.Google Scholar
Wilkinson, J. F. G., 1957b. “Titanomagnetites from a Differentiated Teschenite Sill”, Min. Mag., 31, 443–454.Google Scholar
Wilkinson, J. F. G., 1958. “The Petrology of a Differentiated Teschenite Sill near Gunnedah, New South Wales”, Amer. J. Sci., 256, 1–39.Google Scholar
Winchell, A. N., 1951. Elements of Optical Mineralogy. 4th Ed. New York.Google Scholar
Yoder, H. S. Jr., and Tilley, C. E., 1957. “Basalt Magmas”, Yearb. Garneg. Instn., 56, 156–161.Google Scholar