Early Infill of the Triassic Rift in the Fundy Basin (Nova Scotia): Assessment of the Stratigraphy by Correlative Surfaces in Fluvial Barren Sequences

Leleu, Sophie¹, Brian B. J. Williams¹ (1) University of Aberdeen, Aberdeen, United Kingdom

Exploration for hydrocarbon occurrences has been actively pursued along the eastern North Atlantic margin for over 30 years. The Corrib Field was recently discovered (1997) in Triassic sandstones, offshore Western Ireland. The Triassic sediments of the NW Atlantic margins were deposited in a collage of linked rift basins, extending from eastern North America and West Africa to mid-Norway and eastern Greenland. Basins in excess of 6 km in depth formed due to extension but the timing of rifting is poorly constrained.

The basin infills are dominated by alluvial facies, which vary from the deposits of very large perennial rivers to more ephemeral systems associated with aeolian and evaporitic conditions. The evolution of these systems was a response to multiple episodes of extension, climatic fluctuations and marine influences. In order to evaluate the spatial and temporal evolution of the Atlantic Triassic early rift system, the stratigraphy and the architecture of the fills are being assessed.

In this initial study, the early infill of the Minas Basin (Newark Group, Bay of Fundy) has been examined. During the incipient phase of subsidence, major parts of the basin were shaped by a perennial river system. Coarse conglomeratic units were deposited, abruptly overlain by sandy units. Extensive correlative surfaces have been found within these units. Locally they correspond to calcimorph paleosols but mostly they are erosion surfaces, never associated with fine grained sediments. In red-bed barren sequences, these surfaces allow correlation across the basin and have the potential to predict sand-fairways for reservoir modelling.