Distribution of the Palynomorph Group: Sporomorph Subgroup

Abstract

Muller (1959, p. 28) was one of the first workers to show that the settling rates of most sporomorphs are comparable to those of fine quartz silt. Similarly, Stanley (1965, p. 31) observed that although most sporomorphs are the size of coarse silt grains, their lower density means that they are hydrodynamically equivalent to medium silt or finer siliciclastic grains. Matsushita (1985) also observes that riverborne pollen is hydrodynamically equivalent to particles in the range 11–44 µm (fine to coarse silt). Pollen influx is therefore often strongly correlated with the influx of silt-sized sediment (Clark, 1986, p. 67; Fig. 13.1), the total suspended sediment load of rivers and river discharge (Matsushita, 1985). Consequently, sporomorphs (and most palynomorphs in general) are concentrated in the clay to silt size fraction, i.e. < 63 µm (de Jekhowsky, 1958, p. 1394; Rossignol, 1969, pp. 122-3). Sediments with over 30–40% sand-sized material generally exhibit lower sporomorph abundances (Mudie, 1982, p. 732; cf. Reyre, 1973, pp. 238, 242).