Abstract:
One of the main objectives of the mid-Atlantic transect is to improve dating
resolution of sequences and unconfonnity surfaces. Dinoflagellate cysts from two Ocean
Drilling Program boreholes, the onshore Leg 174AX Ocean View Site and Leg 174A
continental shelf Site 1071, are used to provide age estimates for sequences and
unconfonnities fonned on the New Jersey continental margin during the Miocene epoch.
Despite the occasional lack of dinocysts in barren and oxidized sections, dinocyst
biochronology still offers greater age control than that provided by other microfossils in
marginal marine environments. An early Miocene to late Miocene chronology based on ages
detennined for the two study sites is presented.
In addition, .palynofacies are used to unravel the systems tract character of the
Miocene sequences and provide insight into the effects of taphonomy and preservation of
palynomorphs in marginal marine and shelf environments under different ~ea level
conditions. More precise placement of maximum flooding surfaces is possible through the
identification of condensed sections and palynofacies shifts can also reveal subaerially
exposed sections and surfaces not apparent in seismic or lithological analyses. The problems
with the application of the pollen record in the interpretation of Miocene climate are also
discussed. Palynomorphs provide evidence for a second-order lowering of sea level during
the Miocene, onto which higher order sea level fluctuations are super-imposed. Correlation
of sequences and unconfonnities is attempted between onshore boreholes and from the
onshore Ocean View borehole to offshore Site 1071.
