Abstract

This paper summarizes petrologic work on late Precambrian and Cambrian sandstone suites sampled from the Humber, Piedmont, Gander, and Avalon zones of Newfoundland. Sandstone framework mineralogy was analyzed to answer the question: Does sandstone mineralogy, which primarily reflects sedimentary provenance (the size, shape, composition, relief, and location of source areas) and plate-tectonic setting (proximity to passive or active continental margins), also sharply constrain tectonic models developed to explain an orogenic system?

The answer is no! Newfoundland sandstone compositions are clearly compatible with conventional "Wilson cycle" models that relate the Appalachians to the opening and closure of an ocean basin, which juxtaposed continental shelf (Humber) and continental rise (Piedmont) assemblages of the North American margin with coeval shelf (Avalon) and rise (Gander) units of the African or Avalon margin. A more complex and radically different evolution involving the accretion of terranes, mainly by displacement of microcontinental blocks and adjacent sedimentary basins along large-scale, strike-slip transform faults, however, could generate identical sandstone compositions.

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