Abstract

Two facies sequences. which are interpreted as regressive barrier and barrier-protected deposits, make up the Upper Tertiary Cohansey Sand of southern New Jersey. The facies and environments inferred from them, in the 6 m thick barrier sequence are from the base up: interbedded sand and grit with multidirectional trough sets (surf zone); gently dipping laminated sand (foreshore); burrowed laminated sand with heavy mineral concentrations (backshore-dune); peat (freshwater marsh); and laminated clay (salt water marsh). The facies and inferred environments of the 6 m thick barrier-protected sequence, which conformably caps the barrier sequence, are from the base up: cross-bedded sand characterized by tabular sets (subtidal channel); burrowed cross-bedded sand characterized by trough sets and Ophiomorpha (shallow subtidal channel or channel margin); and burrowed, massive sand (sand flat). Lenticular bodies of interbedded sand and clay (restricted or abandoned tidal channels) are scattered throughout the sequence. The Cohansey sediment was deposited along a submergent coastline receiving abundant sediment and characterized by moderate wave energy and a low tidal range. This 30 m thick quartz arenite deposit was built up during at least two regressive-transgressive cycles.

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