Résumés
Summary
New Brunswick is divided into five tectonostratigraphic zones based upon Cambrian-Ordovician and to a lesser extent Upper Precambrian lithofacies. Sub-zones are distinguished by the characteristics of overlying pre-Carboniferous strata, and tectonic styles.
The paleogeography and tectonic evolution of these zones can be related to the development of two oceanic basins, which transgressed onto the adjacent disrupted continental crust. Opening of the northern oceanic basin began during the Cambrian and closing was completed during late Ordovician time. The southern basin was initiated during the late Precambrian or Cambrian, and closed during the Silurian to early Devonian.
The description of tectonostratigraphic zones in this report is based upon a synthesis of detailed stratigraphie and structural studies carried out in New Brunswick during the past 10 years. Most of these surveys were conducted under the auspicies of the Geological Survey of Canada and Mineral Resources Branch, New Brunswick Department of Natural Resources with financial assistance of the Canada Department of Regional Economic Expansion. The present synthesis constitutes a progress report (Canadian Contribution No. 4) of a continuing investigation conducted in co-operation with the Canadian IGCP (International Geological Correlation Program) Caledonide Orogen Project.
Five major tectonostratigraphic zones (Fig. 1) were delineated in the present study based upon contrasting lithostratigraphic faciès of Cambrian-Ordovician and to a lesser extent, Upper Precambrian strata. Subdivisions of these zones are mainly based upon characteristics of overlying Silurian and Lower Devonian rocks, and structural style. As this study is confined to the pre-Carboniferous tectonic evolution, the Carboniferous strata are designated as cover rocks. Previous structural-stratigraphie subdivisions, based upon the characteristics of the dominant exposed rock units in various belts, were mainly designed to assist in the delineation of mineral zones (Potter et al., 1969) or major structural complexes (Rodgers, 1970). A previous tectonostratigraphic zonation based upon correlation with Newfoundland (Williams et al., 1972) did not adequately represent the geology of New Brunswick. Similarly, previous tectonic interpretations by Bird and Dewey (1970) and McKerrow and Ziegler (1971), required revision, but some aspects of models proposed by Poole (1976) and Rast era/., (1976a) are consistent with the tectonostratigraphic zonation outlined in this report.
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