Tectonic control of Triassic sedimentation in southern New Brunswick: Local and regional implications

Abstract

Both regional and local tectonics controlled the sediment distribution in the Fundy half-graben during the Triassic. Locally, alluvial fans built out into the basin from the western boundary fault along what is now the south shore of New Brunswick. The alluvial fan red beds of the Honeycomb Point Formation are covered by fluvial conglomerates of the Quaco Formation, which in turn are buried by a resurgence of alluvial fan deposition represented by the Echo Cove Formation. Pollen recovered from the upper part of the Echo Cove Formation indicates that, regionally, the system of Triassic-Jurassic grabens along the eastern seaboard is composed of two separate graben systems; one stretching from South Carolina to Connecticut, the other from the Gulf of Maine to the southern Grand Banks. Initial graben formation began at the southern end of each system, followed by successive grabens opening toward the north. The areal distribution of both graben systems appears to have been controlled by four large transform-fault systems from the Middle Triassic through the Jurassic. The age and overall distribution of sediments within the Fundy Basin confirm the existence of a hot spot along the Kelvin Seamount chain and refines determination of the position and timing of the initial rifting that led to the formation of the present Atlantic Ocean.