Avalonian and Cadomian Geology of the North Atlantic, Softcover reprint of the original 1st ed. 1990

Avalonian and Cadomian Geology of the North Atlantic aims to provide region by region syntheses of those terranes which are believed to have once formed part of the Late Proterozoic Avalonian-Cadomian belt. The belt originally comprised a series of volcanic arcs and marginal basins formed during the period c. 700-500 Ma ago, producing a range of calc-alkaline volcanics and intrusives and marginal basin sediments partly founded on continental basement rocks. Originally about 9000 km long, the belt is made up of a number of terranes later separated by the Caledonian orogeny (c. 500- 400 Ma), Variscan orogeny (c. 325 Ma), and the recent opening ofthe Atlantic Ocean (c. 70 Ma). The rocks therefore are now located on both sides of the Atlantic, as far apart as Florida and Czechoslovakia. A possible modern analogue for the Avalonian-Cadomian belt may be the present-day Western Pacific margins. We believe that a synthesis such as this provides the basis for correlation of the timing of events and hence improves our understanding of the underlying tectonic framework of the belt. This book developed from the recognition of, first, our own lack of knowledge of contemporaneous events outwith Armorica, and, second, the likelihood that other researchers working on individual areas or terranes do so in relative isolation. We have therefore commissioned chapters from researchers considered to be experts on their own particular areas.

1 Introduction.- References.- 2 The Longmyndian Supergroup and related Precambrian sediments of England and Wales.- 2.1 Introduction.- 2.2 Longmyndian Supergroup, Welsh Borderland.- 2.2.1 Stratigraphy of the Longmyndian Supergroup.- 2.2.2 Structure of the Longmyndian Supergroup.- 2.2.3 Sedimentology of the Longmyndian Supergroup.- 2.3 Old Radnor Inlier, Welsh Borderland.- 2.4 Charnian Supergroup, Leicestershire.- 2.5 Llangynog Inlier, Dyfed.- 2.6 Other outcrops of Precambrian sediments in England and the Welsh Borderland.- 2.7 Depositional setting of the Precambrian sediments.- References.- 3 Pre-Arenig terranes of northwest Wales.- 3.1 Introduction and historical perspective.- 3.2 The Monian Supergroup.- 3.3 The Coedana Complex.- 3.4 The southeast Anglesey blueschists.- 3.5 The Sara Complex.- 3.6 Regional correlations.- 3.7 Overstep sequences and age constraints.- 3.8 Monian tectonics: an overview.- References.- 4 The Rosslare Complex: a displaced terrane in southeast Ireland.- 4.1 Introduction.- 4.2 The Rosslare Complex: constituents and geological history.- 4.2.1 Early tectono-thermal history.- 4.4.2 The second event (M2).- 4.2.3 The third event (M3).- 4.2.4 The fourth event (M4).- 4.3 Rocks marginal to the Rosslare Complex.- 4.3.1 Tomhaggard Zone.- 4.3.2 Silverspring Zone.- 4.3.3 Tagoat Group.- 4.3.4 The Ballycogly Group.- 4.3.5 Cullenstown Formation.- 4.3.6 Tuskar Group.- 4.4 Caledonian intrusions.- 4.4.1 Saltees Granite.- 4.4.2 Younger basic dykes.- 4.4.3 Carnsore Granite.- 4.5 Conclusions.- References.- 5 Cadomian terranes in the North Armorican Massif, France.- 5.1 Introduction.- 5.2 St. Brieuc terrane (SBT).- 5.2.1 Pre-Cadomian Icartian basement.- 5.2.2 The Penthièvre complex.- 5.2.3 Brioverian supracrustals.- 5.2.4 Cadomian magmatism.- 5.3 St. Malo terrane (SMT).- 5.4 Mancellian terrane (MT).- 5.5 Nature and timing of deformation.- 5.6 Post-Cadomian sedimentation.- 5.7 Regional correlations.- 5.7.1 Guernsey, Sark, Alderney and Cap de la Hague.- 5.7.2 Jersey.- 5.7.3 Lower Normandy.- 5.8 Geotectonic setting.- References.- 6 Precambrian of the Bohemian Massif, Central Europe.- 6.1 Introduction.- 6.2 The Bohemian Massif.- 6.3 The Moldanubian.- 6.4 The Brioverian.- 6.4.1 The Lower Brioverian.- 6.4.2 The Middle Brioverian.- 6.4.3 The Upper Brioverian.- 6.5 Unit boundaries.- 6.6 Cadomian deformation.- 6.7 Cadomian metamorphism and plutonism.- References.- 7 Precambrian terranes in the Iberian Variscan Foldbelt.- 7.1 Introduction.- 7.2 Precambrian sequences and history of northwest Iberia suspect terranes.- 7.3 Stratigraphy of Precambrian sequences in the Iberian terrane.- 7.3.1 Pre-orogenic sequences.- 7.3.2 Syn-orogenic sequences.- 7.4 Late Precambrian tectono-thermal evolution of the Iberian terrane: the Cadomian orogeny.- 7.4.1 Cadomian deformational events.- 7.4.2 Cadomian metamorphism.- 7.4.3 Cadomian igneous activity.- 7.4.4 The Cadomian orogeny in the Iberian terrane from a terrane perspective.- References.- 8 The West African orogens and Circum-Atlantic correlatives.- 8.1 Introduction.- 8.2 Mauritanide, Bassaride, and Rokelide orogens.- 8.2.1 Geologic setting.- 8.2.2 Tectono-thermal history.- 8.2.3 Geophysical controls on tectonic models.- 8.2.4 Geodynamic models.- 8.3 Southern Appalachian orogen.- 8.4 Pre-Cretaceous crystalline basement beneath the Atlantic and Gulf Coastal Plains of the southeastern United States.- 8.4.1 Suwannee terrane.- 8.4.2 Structure.- 8.4.3 Relationship to Appalachian elements.- 8.4.4 Wiggins Uplift.- 8.4.5 Southwestern Alabama Igneous Complex.- 8.4.6 Regional tectonic relations.- 8.5 Appalachian—West African correlations.- 8.6 Terrane accretion in the southern Appalachian orogen.- References.- 9 The Avalon Zone type area: southeastern Newfoundland Appalachians.- 9.1 Introduction.- 9.2 Characteristic lithology and age.- 9.3 Boundaries.- 9.4 Precambrian stratigraphy.- 9.4.1 Pre-635 Ma rocks.- 9.4.2 Late Precambrian (635 Ma–600 Ma) volcanic rocks.- 9.4.3 Late Precambrian (635 Ma–c. 570 Ma) marine sedimentary rocks.- 9.4.4 Latest Precambrian terrestrial sedimentary rocks.- 9.4.5 Latest Precambrian (c. 570 Ma) volcanic rocks.- 9.5 Late Precambrian plutonic rocks.- 9.6 Cambro-Ordovician stratigraphy.- 9.7 Mid-Palaeozoic stratigraphy.- 9.8 Palaeozoic plutonic rocks.- 9.9 Mesozoic magmatism.- 9.10 Tectono-thermal history.- 9.11 Synthesis.- 9.11.1 Deep crust.- 9.11.2 The Burin Group.- 9.11.3 Volcanic and plutonic rocks.- 9.11.4 Sedimentary rocks.- 9.11.5 Latest Precambrian rocks.- 9.11.6 The Eocambrian—Palaeozoic record.- 9.11.7 The Avalonian—Appalachian connection.- References.- 10 The Avalon Composite terrane of Nova Scotia.- 10.1 Introduction.- 10.2 Geological data.- 10.2.1 Mid/Late Proterozoic gneisses.- 10.2.2 Mid/Late Proterozoic platfonnal rocks.- 10.2.3 Late Proterozoic volcano-sedimentary rocks.- 10.2.4 Early Palaeozoic overstep sequences.- 10.3 Discussion.- References.- 11 The Avalon Zone of New Brunswick.- 11.1 Zone definition.- 11.2 Zone boundaries.- 11.3 Unit descriptions.- 11.3.1 Brookville Gneiss.- 11.3.2 Green Head Group.- 11.3.3 Martinon Formation.- 11.3.4 Early amphibolites?.- 11.3.5 Late Precambrian granitoid plutons (Golden Grove suite).- 11.3.6 Coldbrook Group.- 11.3.7 Kingston Dyke Complex(?).- 11.3.8 Late Precambrian (?) mylonite zones.- 11.3.9 ‘Eocambrian’ succession.- 11.3.10 Saint John Group.- 11.4 Regional correlations.- References.- 12 Palaeomagnetic and tectonic constraints on the development of Avalonian—Cadomian terranes in the North Atlantic region.- 12.1 Introduction.- 12.2 Palaeomagnetic constraints on a late Precambrian plate reconstruction.- 12.2.1 The main cratons.- 12.2.2 The intervening terranes.- 12.2.3 Comparison with previous reconstructions.- 12.3 Tectonic synthesis.- References.