Skip to main content
    • Aa
    • Aa

The Rhinns Complex: Proterozoic basement on Islay and Colonsay, Inner Hebrides, Scotland, and on Inishtrahull, NW Ireland

  • R. J. Muir (a1), W. R. Fitches (a1) and A. J. Maltman (a1)

The Precambrian basement on the islands of Islay, Colonsay and Inishtrahull comprises a deformed igneous association of mainly syenite and gabbro, with minor mafic and felsic intrusions. This association is collectively referred to as the Rhinns Complex. Isotopic data indicate that the complex represents new addition of material to the crust at c. 1·8 Ga. The igneous protolith was juvenile mantle-derived material, not reworked Archaean crust. Overall, the complex has an alkalic composition, with major and trace element patterns similar to igneous rocks generated in a subduction-related setting: high LILE/HFSE and LREE/HREE ratios, together with negative Nb, P and Ti anomalies.

The formation of the Rhinns Complex was contemporaneous with the Laxfordian tectonothermal cycle in the Lewisian Complex. These Proterozoic events are most likely associated with an extensive 1·9–1·7 Ga mobile belt around the southern margin of Laurentia-Baltica. As part of this belt, the Rhinns Complex forms a link between the Ketilidian province of South Greenland and the Svecofennian of Scandinavia.

Inherited isotopic signatures in the Caledonian granites on the north side of the Highland Boundary Fault may reflect the presence of a large area of Proterozoic basement (?Rhinns Complex) beneath Scotland and NW Ireland. Alternatively, the Proterozoic signature could be derived from the incorporation of Moine or Dalradian sediment into the granitic magmas.

Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

M. Aftalion & M. D. Max 1987. U-Pb zircon geochronology from the Precambrian Annagh Division gneisses and the Termon Granite, NW County Mayo, Ireland. J GEOL SOC LONDON 144, 401–6.

N. T. Arndt & S. L. Goldstein 1987. Use and abuse of crustformation ages. GEOLOGY 15, 893–5.

A. B. Blaxland , M. Aftalion & O. van Breemen 1979. Pb isotopic composition of feldspars from Scottish Caledonian granites and the nature of the underlying crust. SCOTT J GEOL 15, 139–54.

M. R. Bentley 1988. The Colonsay Group In J. A. Winchester (ed.)Late Proterozoic Stratigraphy of the North Atlantic Regions, 119–30. Glasgow: Blackie.

M. R. Bentley , A. J. Maltman & W. R. Fitches 1988. Colonsay and Islay: A suspect terrane within the Scottish Caledonides. GEOLOGY 16, 26–8.

R. A. Cliff , C. M. Gray & H. Hahma 1983. A Sm-Nd isotopic study of the South Harris Igneous Complex, the Outer Hebrides. CONTRIB MINERAL PETROL 82, 91–8.

J. A. P. Clayburn 1988. The crustal evolution of Central Scotland and the nature of the lower crust: Pb, Nd, and Sr isotope evidence from Caledonian granites. EARTH PLANET SCI LETT 90, 4151.

L. Corriveau 1990. Proterozoic subduction and terrane amalgamation in the southwestern Grenville province, Canada: evidence from ultrapotassic to shoshonitic plutonism. GEOLOGY 18, 614–17.

J. S. Daly , R. J. Muir & R. A. Cliff 1991. A precise U-Pb zircon age for the Inishtrahull syenitic gneiss, County Donegal, Ireland. J GEOL SOC LONDON 148, 639–42.

D. J. De Paolo 1981. Neodymium isotopes in the Colorado Front Range and crust-mantle evolution in the Proterozoic. NATURE 291, 193–6.

A. P. Dickin 1992. Evidence for an Early Proterozoic crustal province in the North Atlantic region. J GEOL SOC LONDON 149, 483–6.

D. J. Fettes & J. R. Mendum 1987. The evolution of the Lewisian complex in the Outer Hebrides. In R. G. Park & J. Tarney (eds) Evolution of the Lewisian and Comparable Precambrian High Grade Terrains, 2744. SPEC PUBL GEOL SOC LONDON 27.

W. R. Fitches , R. J. Muir , A. J. Maltman & M. R. Bentley 1990. Is the Colonsay-west Islay block of SW Scotland an allochthonous terrane? Evidence from Dalradian tillite clasts. J GEOL SOC LONDON 147, 417–20.

C. D. Frost & R. K. O'Nions 1985. Caledonian magma genesis and crustal recycling. J PETROL 26, 515–44.

G. Gaal & R. Gorbatschev 1987. An outline of the Precambrian Evolution of the Baltic Shield. PRECAMB RES 35, 1552.

A. N. Halliday 1984. Coupled Sm-Nd and U-Pb systematics in late Caledonian granites and the basement under northern Britain. NATURE 307, 229–33.

A. N. Halliday , W. E. Stephens , R. H. Hunter , M. A. Menzies , A. P. Dickin & P. J. Hamilton 1985. Isotopic and chemical constraints on the building of the deep Scottish lithosphere. SCOTT J GEOL 21, 465–91.

A. N. Halliday M. Aftalion , O. van Breemen & J. Jocelyn 1979. Petrogenetic significance of Rb-Sr and U-Pb isotopic systems in the 400 Ma old British Isles granitoids and their hosts In A. L. Harris , C. M. Holland & B. E. Leake (eds) The Caledonides of the British Isles–Reviewed, 653–61. SPEC PUBL GEOL SOC LONDON 8.

P. J. Hamilton , N. M. Evensen , R. K. O'Nions & J. Tarney 1979. Sm-Nd systematics of Lewisian gneisses: implications for the origin of granulites. NATURE 277, 25–8.

L. M. Heaman & J. Tarney 1989. U-Pb baddeleyite ages for the Scourie dyke swarm, Scotland: evidence for two distinct intrusion events. NATURE 340, 705–8.

P. F. Hoffman 1988. United plates of America, the birth of a craton: Early Proterozoic assembly and growth of Proto-Laurentia. ANN REV EARTH PLANET SCI 16, 543603.

T. N. Irvine & W. R. A. Baragar 1971. A guide to the chemical classification of the common volcanic rocks. CAN J EARTH SCI 8, 523–48.

Y. Johnson , R. G. Park & J. Winchester 1987. Geochemistry, petrogenesis and tectonic significance of the Early Proterozoic Loch Maree amphibolites. In T. C Paroah , R. D. Beckinsale & D. T. Rickard (eds) Geochemistry and Mineralization of Proterozoic Volcanic Suites, 255–69. SPEC PUBL GEOL SOC LONDON 33.

R. St. J. Lambert & J. G. Holland 1972. A geochronological study of the Lewisian from Loch Laxford to Durness, Sutherland, NW Scotland. SCOTT J GEOL 6, 214–20.

T. B. D. Lyon , R. T. Pidgeon , D. R. Bowes & A. R. Hopgood 1973. Geochronological investigation of the quartzofeldspathic rocks of the Lewisian of Rona, Inner Hebrides. J GEOL SOC LONDON 129, 389402.

F. Marcantonio , A. P. Dickin , R. H. McNutt & L. M. Heaman 1988. A 1800-million-year-old Proterozoic gneiss terrane in Islay with implications for the crustal structure and evolution of Britain. NATURE 335, 62–4.

M. D. Max & C. B. Long 1985. Pre-Caledonian basement in Ireland and its cover relationships. GEOL J 20, 341–66.

A. C. Morton & P. N. Taylor 1991. Geochemical and isotopic constraints on the nature and age of basement rocks from the Rockall Bank, NE Atlantic. J GEOL SOC LONDON 148, 631–34.

R. J. Muir , W. R. Fitches & A. J. Maltman 1992. Rhinns complex: a missing link in the Proterozoic basement of the North Atlantic region. GEOLOGY 20, 1043–46.

N. Nakamura 1974. Determination of REE, Ba, Fe, Mg, Na and K in carbonaceouos and ordinary chondrites. GEOCHIM COSMOCHIM ACTA 38, 757–73.

A. F. Park 1991. Continental growth by accretion: a tectonostratigraphic terrane analysis of the evolution of the western and central Baltic Shield, 2·50 to 1·75 Ga. BULL GEOL SOC AM 103, 522–37.

R. G. Park & J. Tarney 1987. The Lewisian Complex: a typical Precambrian high-grade terrane? In R. G. Park & J. Tarney (eds) Evolution of the Lewisian and Related High Grade Terrains, 1325. SPEC PUBL GEOL SOC LONDON 27.

P. J. Patchett & N. T. Arndt 1986. Nd isotopes and tectonics of 1·9—1·7 Ga crustal genesis. EARTH PLANET SCI LETT 78, 329–38.

P. J. Patchett & D. Bridgwater 1984. Origin of continental crust of 1·9—1·7 Ga age defined by Nd isotopes in the Ketilidian terrain of South Greenland. CONTRIB MINERAL PETROL 87, 311–18.

J. C. Roddick & M. D. Max 1983. A Laxfordian age from the Inishtrahull Platform, Co. Donegal, Ireland. SCOTT J GEOL 19, 97102.

S. S. Sun & W. F. McDonough 1989. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. In A. D. Saunders & J. J. Norry (eds). Magmatism in the Ocean Basins. SPEC PUBL GEOL SOC LONDON 42, 313–45.

F. G. Waters , A. S. Cohen , R. O'Nions K, & M. J. O'Hara 1990. Development of Archaean Lithosphere deduced from chronology and isotope chemistry of Scourie Dykes. EARTH PLANET SCI LETT 97, 241–55.

B. L. Weaver & J. Tarney 1981. Chemical changes during dyke metamorphism in high-grade basement terrains. NATURE 289, 47–9.

B. L. Weaver & J. Tarney 1980. Rare-earth element geochemistry of Lewisian granulite-facies gneisses, northwest Scotland: implications for the petrogenesis of the Archaean lower continental crust. EARTH PLANET SCI LETT 51, 279–96.

G. K. Westbrook & G. J. Borradaile 1978. The geological significance of magnetic anomalies in the region of Islay. SCOTT J GEOL 14, 213–24.

M. J. Whitehouse 1990. An early-Proterozoic age for the Ness anorthosite, Lewis, Outer Hebrides. SCOTT J GEOL 26, 131–36.

M. Wilson 1989. Igneous Petrogenesis. London: Unwin Hyman.

J. A. Winchester & M. D. Max 1984. Geochemistry and origins of the Annagh Division of the Precambrian Erris Complex, NW Co. Mayo, Ireland. PRECAMB RES 25, 397414.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Earth and Environmental Science Transactions of The Royal Society of Edinburgh
  • ISSN: 1755-6910
  • EISSN: 1755-6929
  • URL: /core/journals/earth-and-environmental-science-transactions-of-royal-society-of-edinburgh
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 1 *
Loading metrics...

Abstract views

Total abstract views: 321 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 27th May 2017. This data will be updated every 24 hours.