Abstract:
Despite technological advancements in seismic profiling, microfossil evidence remains essential to understanding the impact of sea level on continental margin architecture. Only with well-dated sediments and accurate reconstructions of sea level can the fundamental tenets of sequence stratigraphy be tested. The relationship between benthic foraminiferal distribution and sea level has been long demonstrated in many regions, and benthic foraminifera are the most reliable paleodepth proxies on siliciclastic margins. Because their distribution is strongly facies-controlled, benthic foraminifera tend not to be very useful biostratigraphic markers, however. Recently, McCarthy et al. (submitted) used variations in P:D (pollen: dinocyst) and in G:P (gonyaulacoid: protoperidinioid dinocysts) in ODP Hole 1072A to reconstruct sea level change on the outer New Jersey shelf. The close agreement between the palynologically-derived sea level curve and the independently-derived sea level curve based on foraminiferal data from the same Hole (Katz et al., submitted) validates palynomorphs as sea level proxies. It also allows us to calibrate the quantitative fluctuations in sea level associated with the palynological variations, at least for the New Jersey shelf, since the distribution of palynomorphs in marine sediments has received relatively little study. In addition to providing an independent sea level reconstruction to compare with the more widely known and accepted benthic foraminiferal curve, palynomorphs offer other advantages: 1) they can usually be found in statistically valid numbers even in most inner neritic environments; 2) palynological assemblages appear to record the degree of oxidation and subaerial exposure; and 3) the palynological sea level proxies are not species-specific, but rather reflect more general relationships, such as the relative contribution of terrigenous vs. marine influx and the rate of mineral particle vs. organic particle accumulation- their application is thus less constrained by geographic and temporal variations.