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.