The distribution and transport processes of sedimentary organic matter (or palynofacies) have been studied on the prograding, siliciclastic, passive margin of New Jersey. The two sites 1072 and 1073 of ODP Leg 174A tested Miocene-Pliocene sections, which provide a proximal-distal transect from shelf (site 1072) to slope (site 1073). The lateral and vertical distributions of palynofacies parameters (essentially continental phytoclasts, and continental and marine palynomorphs) can be compared with seismic, gamma-ray and total organic carbon (TOC) data, thereby contributing to the multidisciplinary study of this margin.
Palynofacies at both locations is dominated by continental constituents. In order to evaluate proximal-distal trends, the main palynofacies parameter used is the ratio of continental to marine palynomorphs (CONT/MAR ratio). The vertical variations of this ratio permit the distinction of intervals which can be equated with seismic sequences. Within a set of prograding clinoforms (e.g. highstand deposits), the CONT/MAR ratio is higher on the shelf than on the slope. On the shelf, its vertical distribution is fairly stable but enables the distinction of aggraded parasequences. On the slope, the ratio shows an upward increase associated with the overall progradation. In transgressive intervals marked by retrogradation, the ratio decreases on both shelf and slope. At both locations, the TOC content is directly linked to the influx of continental phytoclasts and its stratigraphic variations are similar to those of the CONT/MAR ratio. TOC values are lower on the shelf than on the slope because of mineral dilution. FInally, in the prograding sediments, the parallelism between the gamma-ray and CONT/MAR ratio curves supports the hypothesis that the hydrodynamic behavior of continental organic matter is close to that of clay/silt-size particles.
Reprinted with permission from the journal of Northeastern Geology and Environmental Sciences, the Northeastern Science Foundation, and Brooklyn College.