Stratigraphy and sedimentology of post-windsor group redbeds, Sussex area, New Brunswick
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Date
2014
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University of New Brunswick
Abstract
The area around Penobsquis, east of Sussex, New Brunswick, is an important
location of natural resources for the province. In this area, strata of the Mississippian
Horton Group produce natural gas whereas younger strata of the Windsor Group are host
to major potash and rock salt deposits. Overlying these units are more than 1 km of
poorly understood strata, mostly redbeds currently assigned to the Mississippian Mabou
Group. To date, no significant marker beds have been identified in the redbeds and there
has been no useful biostratigraphic recovery, despite recent extraction of close to 5 km
of drill core. Research on these cores broadly identifies siltstone and sandstone at the
base of the redbed succession that gradually coarsen up into conglomerate. The
succession is considered the result of alluvial fan progradation from the northeast.
Within this succession, in many of the cores, is a single interval of localized,
horizontally laminated to cross-stratified, bluish grey sandstone, containing
carbonaceous plant fragments and siltstone intraclasts. To assess the importance of
this interval in the context of the redbed succession, a total of 131 samples of cores
from three boreholes have been analyzed using inductively coupled plasma and
inductively coupled plasma mass spectroscopy techniques to determine a
chemostratigraphy. Study of various elemental ratios delineates two packages, one
that corresponds to the grey interval and overlying redbeds, the other to the underlying
redbeds. Changes in the elemental ratios are interpreted to mark a broader population
of mineral species related to greater variation of provenance and diagenesis in the
upper sediment packages. The rip-up clasts may have been produced by sediment reworking along a boundary that represents an unconformity (in cores, a
disconformity).