Post-Depositional Palynomorph Degradation in Quaternary Shelf Sediments: A Laboratory Experiment Studying the Effects of Progressive Oxidation

Abstract

Although one of the main advantages of palynology over other branches of micropaleontology is the extraordinary resistance of sporopollenin to chemical degradation, this highly inert substance is susceptible to oxidation. Replicate marine samples of late Pleistocene age from the New Jersey shelf were subjected to different degrees of exposure to an oxidizing agent (hydrogen peroxide). Similar palynological trends were identified with increased exposure to hydrogen peroxide, including: 1) a marked decrease in total palynomorph concentration over the first 30 minutes, 2) a marked increase in the gonyaulacacean: protoperidiniacean dinoflagellate cyst ratio which reached infinite values within the first 1/2 to 2 hours, and 3) an increase in the pollen:dinoflagellate cyst ratio over the first 1 to 3 hours. The exercise in progressive oxidation had a large impact on the dinoflagellate cyst assemblages, but a lesser impact on the pollen assemblages, presumably reflecting the selective destruction of the more susceptible taxa long before the accumulation of anemophilous terrestrial palynomorphs. The selective destruction of protoperidiniacean cysts (particularly Brigantedinium spp.) at relatively low levels of oxidation skews the sample toward the more resistant gonyaulacacean cysts (notably Bitectatodinium tepikiense and Spiniferites spp.) and resistant pollen (notably Pinus) and embryophyte spores. This taphonomic skewing should be recognized in biostratigraphic and paleoecological studies in order to avoid spurious interpretations. There are, however, positive applications of palynomorph taphonomy in sedimentological and sequence stratigraphic studies, such as in distinguishing distal turbidites from pelagites, which is difficult to accomplish using sedimentological criteria, and in distinguishing erosional surfaces from condensed sections, both of which generate strong seismic reflections.

Late Quaternary Protoperidinium cysts as indicators of paleoproductivity in the northern Arabian Sea

“…7, ¢eld II). The abrupt drop in relative Protoperidinium abundances at about 2.5 ml/l oxygen is in line with the step-like behavior suggested by the laboratory experiments (Hopkins and McCarthy, 2002).…”

“…Pollen grains can be regarded as ranking among the most resistant palynomorphs (Traverse, 1994), and hence these results suggest that di¡erential preservation among palynomorphs, and notably dinocysts, may not be as straightforward as suggested by recent studies in other regions (see Versteegh and Zonneveld, 2002). Laboratory experiments on palynomorph degradation also show systematic o¡sets depending on the degree of oxidation (Hopkins and McCarthy, 2002). These experiments, however, show that whereas oxidation initially changes relative abundances towards certain taxa, prolonged exposure to an oxidant favors other taxa.…”

Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027)

“…Mudie and McCarthy, 1994) and reduce the probability of re-sedimentation by choosing neritic sites (e.g. McCarthy and Mudie, 1998;Hopkins and McCarthy, 2002;McCarthy et al, 2004); and (c) sedimentary settings that have remained tectonically stable.…”

An effective palynological preparation procedure using hydrogen peroxide

“…The effect of H 2 O 2 on sediments and sedimentary rocks is simultaneously to break down the fabric, and to oxidize the organic material. Because H 2 O 2 is a powerful oxidizing agent, great care must be taken to avoid damage to, and/or degradation of, the less robust palynomorphs (Hopkins and McCarthy, 2002). Leschik (1956) and Brown (1960) described using H 2 O 2 to prepare brown coal; the H 2 O 2 oxidizes the powdered coal prior to other chemical treatment.…”

“…In particular, it is well known that dinoflagellate cysts belonging to the Subfamily Congruentidioideae are highly susceptible to oxidation during processing (Head, 1996). For example, the genus Brigantedinium is extremely prone to destruction by even low levels of oxidation with H 2 O 2 (Hopkins and McCarthy, 2002). It therefore appears that certain taxa throughout the Suborder Peridiniineae are prone to destruction by oxidation.…”