Abstract This volume focuses on the highly populated Canadian Appalachian region. The chapter on the East Greenland Caledonides stands alone and there is no attempt to integrate the geological accounts of the two far removed regions. Rocks of the Canadian Appalachian region are described under four broad temporal divisions: lower Paleozoic and older, middle Paleozoic, upper Paleozoic, and Mesozoic. The rocks of these temporal divisions define geographic zones, belts, basins, and graben, respectively. The area is of special interest because so many modern concepts of mountain building are based on Appalachian rocks and structures.

Abstract The Canadian Appalachian region includes the provinces of insular Newfoundland, Nova Scotia, New Brunswick, Prince Edward Island, and the southern part of Quebec along the south side of the St. Lawrence River (Fig. 1.1). It has an area of approximately 500,000 km 2 and it is widest (600 km) at the Canada-United States International Boundary in New Brunswick and Nova Scotia. A larger unexposed area of Appalachian rocks and structures extends across the Gulf of St. Lawrence and seaward to the Atlantic continental edge. Because of its coastal setting and insular makeup, the region offers tremendous shoreline exposures along marine passages. The Appalachian region is a Paleozoic geological mountain belt or orogen. This means that its rocks have been affected by orogeny, the combined effects of folding, faulting, metamorphism, and plutonism. Paleozoic folds and faults of several generations trend northeastward. Regional metamorphic rocks occupy continuous belts in interior parts of the orogen, and granitic batholiths are common throughout its length (Maps 1 and 2). The word “Appalachian” was first used in a geographic context for the morphological mountains in the southeast United States. It has displaced the word “Acadian” formerly applied to this region of eastern Canada. In the present context, the word “Appalachian” is used for the geological mountain belt without regard for its morphological expression. Like the Cordilleran and Innuitian orogens, the Appalachian Orogen occupies a position peripheral to the stable interior craton of North America (Fig. 1.2). Undeformed Paleozoic rocks of the craton overlie a crystalline Precambrian basement.

Abstract A wealth of detailed data exists for the Canadian Appalachian region. Presentation of data for an orogen as complex as the Appalachian can be problematical. In this chapter the presentation of these data is based on temporal and spatial divisions of rock units. Previous analyses of the Canadian Appalachian region reflected theories in vogue at the time of their undertaking. Thus prior to the wide acceptance of plate tectonics and continental drift, analyses reflected geosynclinal theory. These varied in detail, from the early work of Schuchert (1923) to the sophisticated compound geosynclines that served as a theme for the fifth edition of the Geology and Economic Minerals of Canada (Poole et al., 1970). Subsequent to plate tectonics, conceptual plate models have abounded. Many were contrived on local relations and abandoned as new information on the geology was uncovered. Analyses based on “as is” tectonostratigraphic spatial divisions are those that have met with most success. Thus divisions in the U.S. Appalachians (King, 1950, 1959) such as Appalachian Foreland, Valley and Ridge, Blue Ridge and Piedmont provinces, are still in wide usage. Similarly, the tripartite division of Newfoundland (Williams, 1964, see Fig. 1.16), Western Platform, Central Volcanic Belt and Avalon Platform (Kay and Colbert, 1965) remains little changed, though introduced well before the plate tectonic revolution. These are meaningful geographic divisions used in objective syntheses that describe rocks and structures, while attempting to separate what is known, from what is interpreted. In any objective “as is” account, decisions must be made at

Abstract The five-fold zonation of Humber, Dunnage, Gander, Avalon and Meguma is the first order geographic division of this temporal category. Within each zone the oldest rocks are treated first. Where continuity or correlation is established among distinctive rock packages throughout a zone, each rock package is treated separately, from north to south and province by province. In other cases, all of the lower Paleozoic and older rocks of a zone are treated by provinces, from north to south.

Abstract Middle Paleozoic belts are recognized across the Canadian Appalachian region from Quebec to Nova Scotia, and across the island of Newfoundland. Middle Paleozoic rocks are most extensive along the Quebec-Nova Scotia transect and from northwest to southeast they define the Gaspé, Fredericton, Mascarene, Arisaig, Cape Breton, and Annapolis belts. Middle Paleozoic rocks are less abundant in Newfoundland. From west to east they define the Clam Bank, Springdale, Cape Ray, Badger, Botwood, La Poile, and Fortune belts (Map 2). Rocks of the middle Paleozoic belts do not express the early Paleozoic zonation of the orogen, except in a few cases where middle Paleozoic rocks occur within the confines of a particular zone. The middle Paleozoic belts are less continuous than early Paleozoic zones and there have been few attempts to correlate middle Paleozoic rocks and interpret their significance for the entire Canadian Appalachian region. This is because (a) there are few complete sections with fossiliferous rocks so that the record is fragmentary, (b) occurrences in some places are small and of unknown age, thus precluding broad correlations and linkages across the orogen, (c) there are no middle Paleozoic ophiolite suites, few mélanges, and other rocks that can be related to píate boundaries, (d) contrasts among middle Paleozoic faunas are less pronounced than those among early Paleozoic faunas, and (e) many middle Paleozoic rocks are terrestrial redbeds and associated volcanic rocks that are post accretionary cover sequences, some of which overstep the early Paleozoic elements of the orogen. Stratigraphic sections of most

Abstract The Silurian to mid Devonian Acadian Orogeny resulted in an extensive region of uplands across Atlantic Canada. Isolated occurrences of Lower to Middle Devonian redbed conglomerates, arkosic sandstones and mudstones, locally with intercalated felsic and/or mafic volcanic flows, are the earliest post-orogenic deposits. These became gradually thicker and more widespread so that by Middle Carboniferous time, large tracts of the orogen were buried by sedi-mentary rocks including coarse to fine red and grey terrigenous clastics, oil shales, coal, carbonates, and evaporites. Variation in sediment accumulation rates, syndepositional uplift, and extensive reworking of earlier deposits have greatly complicated the upper Paleozoic litho-stratigraphy. This situation has been complicated further by widespread subsequent faulting, tilting, folding, and erosion. Tilted and/or downfaulted regions in which upper Paleozoic rocks accumulated and/or have been preserved are referred to as "basins" (Fig. 5.1). The name "Maritimes Carboniferous Basin" (Roliff, 1962) or "Maritimes Basin" (Williams, 1974) has in practice become a collective term for the total area in eastern Canada that is presently underlain by upper Paleozoic rocks contained in structural basins, including the offshore. In this sense the "Maritimes Basin" is essentially a basin complex comprising structural remnants of a formerly more extensive area of upper Paleozoic rocks. The designation "Maritimes Basin" is useful however in that it serves to distinguish the area of Upper Paleozoic rocks in Atlantic Canada from the Appalachian, Illinois, and other basins in the United States. The upper Paleozoic rocks contained in the Maritimes Basin complex constitute an approximately east-westtrending region with

Abstract Mesozoic rocks of Atlantic Canada (New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland) are mainly red continental clastic rocks, tholeiitic basalts, and mafic dykes of Triassic and Early Jurassic age. They occur throughout the Bay of Fundy area and locally at Chedabucto Bay (Fig. 6.1), and form sequences up to 3500 m thick in faulted graben; the Fundy Graben and Chedabucto Graben (formerly the Cape Split Trough of Poole et al., 1970). Mafic dykes are more extensive and occur beyond the boundaries of the graben; (Fig. 6.2). Cretaceous rocks include small alkaline intrusions at Notre Dame Bay, Newfoundland and Ford's Bight, Labrador as well as local unconsolidated clay and sand deposits in central Nova Scotia (Fig. 6.1, 6.2) and minor breccias at Ford's Bight. The Mesozoic rocks are related to the early stages of rifting and drifting that led to the opening of the Atlantic Ocean, and they overlie a wide variety of Paleozoic rocks related to the Appalachian or Iapetus cycle of orogenesis. The Fundy Graben is typical of Newark-type graben repre- sented along the length of the Appalachian Orogen as well as offshore (Williams, 1978a). It is bounded by faults and sited, in part, above a deep Carboniferous basin (Minas Basin), in turn parallel to the major Avalon-Meguma zone boundary. Over 150 years have passed since publication of the first report (Jackson and Alger, 1829) on Mesozoic rocks of Atlantic Canada. Many scientists have worked on these rocks over the years but the comprehensive observations of Powers (1916)

Abstract Geophysical studies of the Canadian Appalachian region have contributed primarily to an understanding of the structural features at depth through the application of gravity, magnetic, and seismic techniques supplemented to a lesser extent by geomagnetic depth sounding and magne- totelluric and heat flow studies. In addition, gravity and magnetic maps allow comparisons between geological and geophysical features of the region. These comparisons may be used to extend the geological features to regions of poor or no exposure, for example to the northern offshore and Gulf of St. Lawrence. Paleomagnetic results have gen- erated discussion regarding the relative horizontal dis- placements of large parts of the orogen. Offshore geophysical surveys provided the first evidence of the existence of the thick Tertiary and Mesozoic sedimentary sequence on the continental shelf and slope which are the target of extensive petroleum exploration and activity. The geophysical data have been collected over the last 30 years but the most exciting interpretations are arising from the integration of the older data sets with the results from the new, deep, seismic reflection data. New aero- magnetic data are also adding immensely to our understanding of the nature of the crust in water-covered areas, particularly the critical area between Newfoundland and Nova Scotia where geophysics is the only method of tracing the geological features across the Cabot Strait. The inter- pretation of each data set as it was collected and published was undertaken in the context of contemporary geological models. Many such models are now obsolete. The present

Abstract Plutonic rocks make up about one quarter of the exposed Canadian Appalachians, occuring in all tectonostrati- graphic zones. Plutons range in age from Middle Protero- zoic to Cretaceous, but ages of plutons in particular zones are restricted to small parts of this range. Compositions range from ultramafie to high-silica granites. Overall there is a noticeable deficiency of mafic compositions (dioritic and more mafic) compared to other well-studied orogenic belts such as the Cordillera. Late Precambrian, early Paleozoic, and Mesozoic magmatism produced mafic dyke swarms of major dimensions, and significant amounts of mafic plu- tonic rocks. Most other periods of magmatism produced few dykes, and mafic plutonic rocks are either subordinate to salic phases or virtually absent. Despite their large area, plutonic rocks received rela- tively little attention prior to 1965 because of the strati- graphic and structural focus of much of the early geological work in this region. Interest in the plutonic rocks increased markedly with the realization that they hold important clues to the tectonic history of the region, and may contain significant mineral deposits. The pioneering compilation of Neale and Pajari (1972) served as a prototype for provincial compilations (Strong, 1980; Clarke et al., 1980; Fyffe et al., 1981) and stimulated studies of individual plutons. During the past decade, mainly under the sponsorship of provincial and federal governments, a great deal of work has been undertaken on plutonic rocks of the Canadian Appalachian region. The general outlines and petrography of most plutons are now known, and bulk rock

Abstract Metallogeny is the branch of geology that seeks to define the genetic relationships between the geological history of an area and its mineral deposits. Mineral deposits, in the broadest sense, form part of the same geological record as less-valuable rocks, and were deposited in response to processes in the same geological and tectonic environ- ments. Mineral deposit studies both contribute to and bene- fit from understanding of the regional geological and tectonic development of an area. The deposits in some cases provide important data as to the geological processes opera- tive at different times. On the other hand, regional geological models are essential to help constrain possible met- allogenic models, when a large number of deposits having formed at several different times are present. As recognized many years ago by McCartney and Potter (1962), the Canadian Appalachians provide a particularly good laboratory for the study of regional metallogeny. The regional geology is relatively well understood and inter- preted in terms of well constrained tectonic models and a wide variety of mineral deposit types and ages provide a record of mineralization that spans the entire history of the orogen. This chapter considers the nature of the mineral deposits in the Canadian Appalachians and their place in the geological and tectonic framework of the orogen. The concept of metallogeny, as distinct from economic geology, was pioneered by de Launay (1900, 1913) who identified consistencies in the regional geographical variations in the occurrence of ores. Perhaps his major contribution was the introduction of

Abstract Fossils provide essential information for the determination of prior locations of the components of ancient orogenic belts such as the Appalachians. In this chapter we review the record of fossils from the Canadian Appalachians that, together with those from the Appalachians in the United States (Neuman et al., 1989), assist in determining the paleogeographic and tectonic evolution of this orogenic system. The rocks of the Canadian Appalachians are more fossiliferous than their counterparts in the United States because they are generally less deformed and metamor- phosed, and because there are important differences in the geology of the orogenic belt in the two countries. Paleontological studies in Canada have long contributed to the development of ideas on the history of the orogen. The Cambrian faunas of the Avalon Zone in Newfoundland and Southern New Brunswick, and correlatives in north- western Europe were assigned by Walcott (1891) to an “Atlantic Coast Province”, considered by him to be diíferent from those of the “Appalachian Province” elsewhere in the Canadian and U.S. Appalachians. Following the introduc- tion of the idea of continental drift (Wegener, 1928), Grabau (1936) explained the similarity of the stratigraphy and faunas of eastern North America and northwestern Europe by deposition in contiguous synclines that were parts of his hypothetical “Pangea.” After the general acceptance of continental drift, Wilson (1966) proposed that a Paleozoic “proto-Atlantic Ocean” preceded the present Atlantic. In his view the Atlantic Cambrian faunas populated the eastern margin of the “proto-Atlantic Ocean”, contempora- neous Pacific faunas populated its

Abstract This chapter summarizes, and repeats without referencing, information presented in preceding chapters. Some of these chapters were written more than 5 years ago and there have been important subsequent changes. A few new ref- erences are therefore cited. This chapter was written also with an eye toward suitability for a Canadian overview volume. The summary follows the systematics introduced ear- lier, treating all rocks according to the four broad temporal divisions; lower Paleozoic and older rocks, middle Paleozoic rocks, upper Paleozoic rocks, and Mesozoic rocks. The rocks of each temporal division are subdivided into spatial divisions. Thus, the lower Paleozoic and older rocks are separated into the Humber, Dunnage, Gander, Avalon, and Meguma zones and subzones as depicted in Figure 11.1. The middle Paleozoic rocks are separated into belts: Gaspé, Fredericton, Mascarene, Arisaig, Cape Breton, and Annapolis for the mainland; and Clam Bank, Springdale, Cape Ray, Badger, La Poile, Botwood, and Fortune for Newfoundland (Fig. 11.2). The upper Paleozoic rocks define a number of basins, and Mesozoic rocks define graben (Fig. 11.3). A compilation and classification of volcanic rocks for the Canadian Appalachian region is provided for comparisons with other divisions (Fig. 11.4). The Canadian Appalachians provide an excellent example of an orogen that built up through accretion and eventual continental collision. In this model of a typical Wilson cycle, the Humber Zone is the Appalachian miogeocline or continental margin of Laurentia, and outboard zones are accreted parts of the orogen or suspect terranes. These zones are the fundamental divisions

Abstract Greenland, the largest island in the world, is situated at the northeast corner of the North American plate. Nares Strait, a channel in places as narrow as 20 km, separates western North Greenland from Ellesmere Island. Geologi- cally the are as on the two sides of the strait have much in common, and there is little evidence to support the large sinistral strike-slip movements proposed along the strait in response to seafloor spreading farther south (see Dawes and Kerr, 1982; Okulitch et al., 1990). Baffin Bay and Labrador Sea, which separate the coast of West Greenland from the coasts of Baffin Island and Labrador, developed by seafloor spreading that began at about the Cretaceous- Tertiary boundary and terminated by the Early Oligocene. East of Greenland the North Atlantic Ocean opened during the Tertiary, and fragmented the Caledonide Orogen (Fig. 12.1). In East Greenland the Caledonides can be traced from latitude 70° to 82°N. Predrift reconstructions produce a variety of configurations for the reassembled Caledonide Orogen, but there is a general consensus that parts of Spitsbergen represent the northern extension of the East Greenland Caledonides, whereas the Southern extension is to be seen in the Caledonides of the British Isles and the Appalachians of eastern North America (Harland and Gayer, 1972; Harland, 1985; Ziegler, 1985). General reviews of the East Greenland Caledonides are given by Haller (1971), Henriksen and Higgins (1976), Higgins and Phillips (1979), and Henriksen (1985). The East Greenland Caledonides form a coastal belt 1200 km long and up

Abstract The continental margin transect program evolved through a desire to define the specific characteristics of North America’s modern continental margins and to compare the modern margins with Paleozoic examples, now found within the continent. Thus, the features of modern margins can be used to locate and elucidate the structures of ancient analogues. Conversely, the exposed rocks of ancient margins provide an insight into the evolution and deep structures of modern examples. Ocean-continental transitions, rifting mechanisms, development of sedimentary basins, processes of continental breakup, and ancestral controls are all features that warrant comparison between modern and ancient examples. The Atlantic coast has the best-known passive margin of North America. Inboard of it is the Appalachian Mountain chain, which records a clear history of late Precambrian rifting and the passive development of a Paleozoic continental margin. Transects across both these modern and ancient examples provide information on scale and detail that is useful for comparisons. The modern continental margin of eastern Canada (Fig. 1a, 1b) has a wider variety of ages and styles than that of its eastern United States counterpart. Segments of the margin southeast of Nova Scotia and east of Labrador are typical of rifted margins, though of different ages. Between them lies the tortuous segments of the northern and eastern Grand Banks where rifting and subsidence occurred over a broad area of the continental shelf. In contrast, the southern boundary of the Grand Banks is a transform segment. Rocks of the Appalachian Paleozoic margin are best preserved and exposed

The climactic, middle Paleozoic event that affected the Newfoundland Appalachians has been referred to traditionally as Acadian orogeny. The latest Field studies and isotopic ages indicate that it began in the Early Silurian and continued into the Devonian. It affected the Newfoundland Humber, Dunnage, and Gander zones and western parts of the Avalon Zone. Intensities of the effects of the orogeny decrease westward across the Humber Zone (Appalachian miogeocline) and eastward across the onland Avalon Zone. Offshore, the wide Avalon Zone is virtually unaffected by Paleozoic deformation. The most intense regional metamorphism coincides mainly with the Gander Zone. Plutonism affected a wider area—from the eastern Humber Zone of White Bay to the western Avalon Zone of Placentia Bay. Deformation affected the widest area, from the Appalachian Structural front, which defines the western boundary of the Humber Zone, to the Avalon Peninsula of the western Avalon Zone. A change from marine to terrestrial conditions preceded the Silurian-Devonian deformation. Uninterrupted shallow marine conditions prevailed in bordering regions outside the Acadian deformed zone. The Acadian orogen spans the eastern portion of the Grenville lower crustal block that underlies the Humber Zone and western parts of the Dunnage Zone. It spans the Central lower crustal block that underlies eastern parts of the Dunnage Zone and the Gander Zone, and it spans the western part of the Avalon lower crustal block. Orogenic effects are most intense above the narrow Central lower crustal block and diminish outward across the margins of the opposing Grenville and Avalon lower crustal blocks. This spatial relationship between the surface orogen and lower crustal blocks implies that collisional interaction among lower crustal blocks controlled the tectonothermal effects of Acadian orogeny.