My first job as a palynologist was with Shell Development Company in Houston, Texas. I was hired in 1955, and my assignment was to study pollen and spores in recent sediments in whatever way or ways I wished. For the next seven years I did this for Shell, and have, since then, been fascinated by the relationship between pollen, spores and other organic particles to the organisms from which they derive and to the sediments in which they occur as fossils. When Dr. Mary Dettmann invited me to organize a symposium on this subject for the 6th International Palynological Congress in Brisbane, Australia (August–September, 1988), I accepted enthusiastically. After the Congress I invited the participants in the symposium to produce chapters on this subject for a proposed book. However, as it worked out, there is very slight overlap between this volume and that symposium. For one reason or another, some of the participants in Brisbane did not prepare chapters. Others (including me) felt that the papers they had published in the Proceedings volume for the Congress (Review of Palaeobotany and Palynology, 64, 1990) need not be duplicated, and they produced something quite different for this book. It is also very significant for the shape of the present volume that I invited a number of people to write chapters who were not involved in the symposium at all, in order to assure a wide-ranging coverage of the subject. The new project was inspired by the symposium, but publishes a much different and broader array of material than was presented in Australia in 1988.

Introduction

The palynology of sedimentary cycles is based on the study of dispersed organic matter in rocks of various depositional lithofacies. This chapter describes how different kinds of organic particles can be used to detect depositional environments and their migration in response to change in sea level relative to the land surface. Episodes of marine transgression and regression affect the distribution and concentration of organic particles such as pollen grains and spores, algal fossils, the conductive tissue and cuticle of land plants, recycled palynomorphs and inertinite, and fecal amorphous debris. Several examples illustrate the evidence that palynology provides for cycles of transgression and regression. These were selected from contrasting lithological types, for example, siliciclastic sand to lime mud; different depositional environments, for example, shallow shelf versus carbonate platform; and different geologic ages, for example, Middle Jurassic, Late Cretaceous-Danian. An example of Permian-Triassic age illustrates how reworked palynomorphs can be used to detect cyclicity in the sedimentary record.

Organic particle sedimentology

The vast majority of particulate organic matter deposited in marine sediments consists of admixtures of material of both terrestrial and marine origin. The mixing of material from both sources occurs on the deep sea floor as well as on the shallow shelf. Commonly, one or two components predominate over others, and these can be used to trace the principal origin of the organic matter. Other parameters, such as the diversity and morphological sorting of organic particles, can be used to interpret hydrodynamic and ecological processes operating in the area of deposition.

Introduction

Paleopalynology is the study of microscopic structurally preserved organic matter which can be extracted from siliciclastic rocks by acid maceration. Traditionally, paleopalynology includes the study of various algal remains, microscopic parts of some protists and animals, spores of cryptogamic plants and fungi, and the pollen grains of seed-bearing plants, all of which are thought to possess a resistant organic outer wall composed of sporopollenin, chitin, or a similar derivative. This definition restricts the palynological record prior to the evolution of the terrestrial embryophytic plants to the resistant remains of algal phytoplankton, chitinous scolecodonts, and possible zooplankton such as chitinozoans. However, in this chapter I expand the view of paleopalynology to include some other structurally intact, microscopic organic remains which are thought to be of planktonic origin. This means that phytoplankton preserved in both siliciclastic (Acritarcha) and in cherty carbonate facies (Cryptarcha, sensu Diver & Peat, 1979)) is included.

In broadest terms, the study of palynomorphs as sedimentary particles concerns the distribution and dynamics of biological carbon through geologic time. The stratigraphic record of microplankton is of great importance in modeling the dynamics of former marine and terrestrial ecosystems. The changes in the flux of carbon brought about by the rise of a standing biomass in terrestrial habitats represents a fundamental shift in the distribution of biogenic carbon on the earth. This shift occurred during the Silurian Period and is marked by the fossil record of the cryptospores, which represent the palynological evidence of a transition to an embryophytedominated terrestrial ecosystem (Strother, 1991).

Introduction

Palynologists extract fossil spores and pollen (collectively ‘sporomorphs’) from rocks representing many different sedimentary environments; these are used as indicators of the surrounding vegetation and climate as well as for stratigraphy. They are of particular use to stratigraphers, as they may be found in both marine and terrestrial sediments and can therefore be used as a link between the two environments.

In the past it was common to believe that most of the pollen was transported to the sediment via the atmosphere as a ‘pollen rain.’ This pollen rain was considered to be relatively uniform over a wide area.

The distribution of pollen through the atmosphere has been studied by many authors (for example, Lanner, 1966; Janssen, 1973). Numerous experiments have been carried out on the dispersion of pollen from both point sources (Colwell, 1951; Chamberlain, 1966) and from forests (Lanner, 1966). Some of these studies were initiated by investigators in other fields of study. May (1958), for example, was attempting to model the dispersion of radioactive particles in the atmosphere and she used Lycopodium spores to do this.

As palynologists recognized the need to be able to differentiate between pollen that had travelled a few meters from that which had arrived at the site from several kilometers away, the pollen rain was interpreted as having three components with arbitrary boundaries: (1) ‘local’ (sporomorphs deposited within a few tens of meters of their source plant), (2) ‘extra-local’ (deposited within a few hundred meters of the source), and (3) ‘regional’ (deposited more than a few hundred meters from their source).

Introduction

Research by Fisher and McGowen (1967) on the stratigraphy and sedimentology of the upper Paleocene part of the Wilcox Group in the Gulf Coast Basin in Texas (Fig. 12.1C) resulted in the definition of seven ancient depositional systems in the outcropping and subsurface Wilcox. Coal-forming peat had accumulated within four of them. Traverse and Nichols (1967), Nichols (1970), and Nichols and Traverse (1971) identified paleoecologically significant groups of palynomorphs within assemblages from outcropping Wilcox coal beds in an effort to distinguish palynologically the interrelated but differing depositional systems defined by Fisher and McGowen.

In the Powder River Basin of Montana and Wyoming (Fig. 12.IB), studies on lower Tertiary coal deposits of the Fort Union Formation by Flores (1981,1983), Flores and Hanley (1984), and Hanley and Flores (1987) provided a similar stratigraphic and sedimentologic framework for palynological studies. Depositional models for coal formation in this region were proposed by Pocknall (1986a) and Pocknall and Flores (1987); see also Satchell (1984; 1985). As in the Gulf Coast study, an aspect of research on Powder River Basin coal beds was the identification of groups of palynomorphs that represent the depositional environments.

In this chapter we expand upon the interpretations of Nichols and Traverse (1971) for upper Paleocene coal beds of the Gulf Coast Basin and compare them with those obtained by Pocknall and Flores (1987) for upper Paleocene coal beds in the Powder River Basin. We use palynofacies to characterize and contrast coal-depositional environments within these regions.

Introduction

The research presented here was originally done in 1958–1962, when I was working for Shell Development Company in Houston, Texas. It represents the final segment of investigations I carried out for Shell on the palynology of modern sediments. The basic information for this last sub-project was submitted to Shell as an internal report after I left the company in 1962. The overall project included studies of a carbonate platform (the Great Bahama Bank; Traverse & Ginsburg, 1966), and the Trinity River – Trinity Bay – Galveston Bay clastic depositional complex of Texas (Traverse, 1990, 1992). The lower Trinity river system was selected for study because: (1) the river system was at that time relatively natural, undisturbed by dams, (2) Shell Development Company geologists had studied sedimentation in the area, and (3) the lower river and associated bays were easily accessible from my place of employment.

That these research results are presented so long after they were obtained can be justified only in that they represent a previously unpublished, unique data-set for a medium-sized relatively undisturbed river and associated bays, smaller streams, and adjacent near shore parts of the Gulf of Mexico. Inasmuch as I have published results of studies of palynomorphs in the water of part of the area (Traverse, 1990,1992), it also seems desirable to complete the story by presenting information available for the palynomorph content of surface sediment of the region. It should be emphasized that throughout this chapter I deal with the status of palynomorph sedimentation in the area as it was about 1960.

Introduction

Most palynological investigations start with the maceration of sediments for the removal of their inorganic content. Not only does this separate the palynomorphs but it often leaves a residue of other organic remains which can be studied microscopically as well as chemically. There is great variation in the terms applied to these non-palynomorph remains since most of the people studying them are geologists lacking knowledge of plant anatomy and morphology. Confusing, often misleading and even wrong terms have been given to some broken plant parts. It is the purpose of this chapter to help establish a standard terminology for the microscopist.

Three different approaches are given to the study of these fragments according to the nature of the problems to be investigated and according to the background of the authors:

(1) Coal petrologists (see Brooks, 1981; Durand, 1980) still use versions of Stopes' (1935) terminology for the organic components of macerals. Teichmüller and Teichmüller (1968) related these studies to a morphological approach.

(2) Geochemical studies of kerogen (Crum-Brown, 1912) have recently been summarized by Tissot et al., (1974) and Burgess (1974).

(3) Paleobotanical (including paleopalynological) studies of palynodebris are the central scope of this chapter, and the visual microscopical observations so derived form the basis of these comments on their classification. It attempts to encourage a standard terminology for types of visually observed palynodebris compatible with all facies, and as far as possible to relate these types to a functional sedimentological setting for microscopical use.

Introduction

Most quantitative palynologic work uses counts or percentages of taxa (i.e., relative frequency) as the basic measure of occurrence for analysis. Relative frequency has proved satisfactory for most purposes, but it has some undesirable properties. Most notable among these is the closed sum, that is, percentages always sum to 100 and counts sum to a fixed total (basically 100 times a constant). If one taxon goes up in frequency, the remaining taxa as a whole must go down. Percentages, therefore, have an artificial, imposed negative correlation that can distort multivariate ordinations and classifications, and can render common confirmatory statistical analysis such as analysis of variance invalid. Transformations to solve this problem for compositional data in general have been devised (Aitchison, 1986), but involve the logistic normal transformation which uses logarithms of the raw data. Because paleontological data matrices usually contain numerous zeroes, Aitchison's method has to be altered to change zeroes to small positive values. This alteration complicates matters, and the logistic normal transformation has not been used much in paleontology. Use of the logistic normal is treated more fully in Kovach and Batten (Chap. 18 this volume). The complications in using even transformed relative frequency data suggest that other possibilities for measuring quantitative abundance should be examined.

Use of palynomorph concentration (number of grains per unit volume or weight of sediment analyzed) is not common in pre-Quaternary palynology, but has theoretical advantages. Analyses of concentration can be based on total concentration of all palynomorphs or on concentrations of individual taxa in a sample. Concentrations are useful because they may distinguish depositional environments and because concentrations have favorable statistical properties.

Introduction

Palynological study of the organic matter content of sediments reveals information about the nature and state of preservation of constituent elements of both the sediments in general and the organic matter in particular. These observations have led to the establishment of a number of criteria to assist in reconstruction of the paleogeographical and sedimentological conditions prevailing at the time of deposition, as well as the geological history of the sediment.

Several authors have proposed relationships which may have existed between paleogeography, in the broadest sense, and the microscopic character of the sedimentary organic matter. The ultimate aim of these investigations has been to understand the origin and alteration of this organic material, and, more generally, of the sediment in which it is preserved (Haseldonckx, 1974; Hart, 1986; Pocock et al., 1987). Most often these studies have concentrated on Pre-Quaternary sedimentary formations. The paleogeography prevailing at the time of deposition can be deciphered only from reconstructions where hypotheses sometimes become important, reducing the validity of the proposed conclusions.

It was to alleviate such difficulties, and particularly to understand and consequently interpret the geological data more accurately, that the ORGON project, a series of French scientific cruise-expeditions with organic geochemical goals, was undertaken during the years 1976–1983, to study the organic content of Late. Pleistocene to Holocene deposits from various ocean environments (see Fig. 8.1). Only extant phenomena which can be described or quantified are taken into consideration. This project, essentially based on observed facts, enables us to delimit, in some well-defined cases, the role and importance of the various factors affecting the nature and state of preservation of organic matter in marine sediments.

Introduction

During the past few years there has been considerable interest in the way in which the composition of the acid resistant organic content of sedimentary rocks can be used to aid the interpretation of depositional environments. However, much of the published work has not involved fully comprehensive analyses. There has been a tendency to concentrate either on the distribution of palynomorphs at the expense of less well characterized phytoclasts, or on the shape and composition of the particulate detritus recovered, with scant attention being paid to the environmental implications of the presence of individual species of microfossils. As a result, much information of potential value to the aims of palynofacies analysis has been lost. In addition, comparatively little use has been made of numerical methods in analyzing and interpreting the data. Multivariate methods, which reduce the dimensionality of the data, can bring the most important trends to the fore and provide a quantitative basis for assessing these in the light of lithology and depositional environment. They also provide a graphical means of presenting the results much more effectively than through written descriptions alone.

In this chapter we review a variety of approaches that may be taken to analyze palynofacies and depositional environments, concentrating on the use of quantitative and multivariate methods. In order to demonstrate the usefulness of these techniques, we re-analyze a number of previously published sets of palynological and palynofacies data with principal components and cluster analyses, using the computer program MVSP (Kovach, 1990). We also discuss approaches other authors have taken in applying numerical methods to palynofacies studies in order to demonstrate the range of techniques available.

Introduction

Pollen analyses form the data base for many types of inferences ranging from sequential changes in past environments to lifestyles and diets of prehistoric human populations. In all cases, interpretation of pollen data must account for those factors that may have influenced the composition of the original pollen rain, and also for those factors that may have altered the composition of the pollen assemblage following deposition.

During the last 50 years palynologists have learned that there are many complex factors that determine the original composition of the pollen rain in an arid region. These include mode of pollination, differences in pollen production, differential dispersion patterns, and the size, weight, and aerodynamic ability of pollen types to remain airborne (see Chaps. 3, 13, 14, and other related chapters in this volume). Following deposition, other factors influence eventual loss or recovery of specific pollen types. These factors include pollen redeposition, the chemical composition of a pollen grain's exine, its morphological shape and types of surface ornamentation, and its susceptibility to various types of degradation processes including those from mechanical, chemical, or biological agents (Bryant, 1978, 1988; Bryant & Holloway, 1983; Hollo way, 1989; O'Rourke, 1990). In this chapter we focus on the post depositional degradation processes.

One of the first agents that can affect pollen grains is mechanical degradation. After pollen is released from its source, it can become abraded or broken during the transportation phase. These alterations can result from impact or from changes in the natural environment.

Introduction

Organic matter found dispersed in aqueous systems and in sedimentary rocks consists of organic compounds derived from both autochthonous and allochthonous sources. The form of this material ranges from wellpreserved particulate organic matter (POM or macerals) to dissolved organic matter (DOM). The total mass of this organic matter is very large, and Mclver (1967) notes that it is 500–1000 times the amount found in coal, and 10000 times the amount in all organisms living at the present time. Both Weeks (1958) and Hunt (1962) estimated the total mass to be 3.2 × 1015 metric tons.

The microscopic analysis of POM has gained widespread acceptance as a reliable means of assessing the petroleum source potential and thermal maturity of rocks in sedimentary basins. Numerous studies, using various classifications of organic matter, indicate that a relationship exists between POM and petroleum source potential (e.g., Burgess, 1974; Dow, 1977; Teichmüller & Wolf, 1977; Robert, 1981; Mukhopadhyay et al., 1985; Senftle et al., 1987). Thermal maturity measurements in the form of vitrinite reflectance and transmitted color are routine in petroleum source rock evaluation (Staplin, 1969; Bostick, 1971, 1974; Castaño & Sparks, 1974; Dow, 1977; Peters et al., 1911; Hunt, 1979; Dow & O'Connor, 1982; Saxby, 1982; Stach et al., 1982; Pearson, 1984; Tissot & Welte, 1984; Waples, 1985).

Contemporary depositional environments contain many clues to the origin of the sediments accumulating on the depositional surface. Unfortunately, rocks rarely preserve sufficient information to reconstruct accurately the original depositional environment. Information is lost principally at the sediment–water interface and during the diagenetic stage of lithogenesis.

Introduction

Interest in understanding the reaction of plant communities to the Cretaceous-Tertiary (K/T) boundary event has focused increased attention on late Maastrichtian and Early Paleocene palynofloras. Both the relative abundances of major groups of palynomorphs and range truncations have been used to infer changes in terrestrial environments coincident with the K/T boundary in mid-continental North America (Orth et al., 1981; Tschudy et al., 1984; Nichols et al., 1986; Bohor et al., 1987; Lerbekmo et al., 1987; Fleming & Nichols, 1990; Nichols, 1990; Sweet et al., 1990; Nichols & Fleming, 1991; Sweet & Braman, 1992). These criteria sometimes are used to emphasize the more catastrophic aspects of floral change at the K/T boundary (Orth et al., 1981; Tschudy et al., 1984; Nichols et al., 1986; Bohor et al., 1987; Fleming & Nichols, 1990). In other publications the relative abundance spikes and range truncations are considered to be part of a continuum of change across the boundary (Tschudy & Tschudy, 1986; Lerbekmo et al., 1987; Sweet et al., 1990; Sweet & Braman, 1992). It now is generally accepted that many morphologically complex species of angiosperm pollen became extinct at or within an interval immediately contiguous to the K/T boundary, and that there is a causal connection between these extinctions and the K/T event.

The dominant late Maastrichtian miospore species often represent flowering plants (Tschudy & Tschudy, 1986; Lerbekmo et al., 1987; Sweet et al., 1990). A dramatic shift occurs in the relative abundances of spores and pollen immediately after the K/T extinction event in most North American terrestrial sections.

Introduction

This annotated bibliography contains entries on the modern transport and deposition of pollen. As a rule, studies that infer transport and deposition from older sediments are omitted. A few entries without annotations (e.g., Vronskiy 1981, 1984) are included for completeness. Some less well-known papers have longer summaries, to aid readers who might not have ready access to the originals.

Occasionally, secondary papers are cited within primary entries. If such a paper is treated in this chapter it is marked with an asterisk; if not treated here, its full bibliographic citation may be found by consulting the primary publication annotated here.

Acknowledgments

I have assembled this bibliography over a number of years. I would like to thank David L. Dilcher and Alfred Traverse for their encouragement, and to express much gratitude to the persevering Interlibrary Loan librarians, particularly in the Earth and Mineral Sciences Library at the Pennsylvania State University, for their help in obtaining many papers.

Annotated Bibliography

Andersen, S. Th. (1967). Tree-pollen rain in a mixed deciduous forest in South Jutland (Denmark). Review of Palaeobotany and Palynology, 3, 267 –75.

Transects through a deciduous forest show that ‘pollen percentages decrease strongly 20–30 m from dense stands of the species in question, and the pollen spectra thus appear to represent highly local vegetation’ (p. 269).

Introduction

In the Mediterranean region, several studies have been devoted to the distribution of pollen in coastal marine areas (Rossignol, 1961; Koreneva, 1971; Rossignol & Pastouret, 1971; Belfiore et al., 1981; Brun, 1983). Other studies have tried to understand the pollen rain in mountain areas where peat bogs are excellent pollen recorders (Reille, 1975; Beaulieu, 1977). However, little is known about how much of the pollen produced in high and middle altitudes is transported to the area of sedimentation near the shoreline, and how it is transported.

The region of Calvi in Corsica is typical of Mediterranean climatic conditions, where mountains rise to 2000 m a short distance (20 km) from the coast, with rather humid climate at the top (near 2000 mm precipitation, concentrated during the cold season; Simi, 1964), and rather dry climate (near 700 mm precipitation) near the coast. Autumn, winter, or spring high rainfall on the top and on steep slopes (Fig. 5.1) produces huge and violent floods (Guilcher, 1979), which carry large stones that accumulate on the narrow coastal plain and which also deliver fine material to the sea. During the dry season (summer) the rivers are at minimum flow and often vanish in the coarse sediments of the coastal plain. Two small rivers enter the sea near Calvi, the Fiume Secco and the Ficarella (Fig. 5.1).

Introduction

The Quaternary Period can serve as a model for earlier times in demonstrating the diversity of data that can be analyzed to reveal the nature of past biota and environments. Late Quaternary palynomorphs are a particularly versatile and informative group of fossils because they are preserved in a variety of deposits, and in most cases can be referred to existing genera. Pollen can be used to infer past climates, to reconstruct former vegetation, and to provide an environmental framework for archaeological investigations, amongst other applications. The characteristics of pollen production, dispersal, deposition and preservation at each site dictate the type of application to which the individual site is suited, and determine the detail and reliability of the inferred reconstructions. In this chapter I explore some of the methodologies of environmental and community reconstruction that exploit particular dispersal and sedimentation properties of pollen grains. These same properties impose the limits for the level of detail that can be justified in the final interpretation.

The concept of a source area of pollen origin for each collecting basin is introduced by Jackson in Chapter 14 (this volume). This source area, which is controlled by the method of pollen dispersal, dictates the type of reconstruction that can be created from any given site. The size of these source areas has been investigated both theoretically and empirically. Tauber (1965) began from first principles by using the physical laws governing the dispersion of small particles. Studies of pollen dispersal from isolated trees or small, discrete stands developed this approach (e.g. Turner 1964; Janssen 1984), and Kabailiene (1969) presented a sophisticated algebraic analysis of pollen dispersal over an entire landscape.

Introduction

In the reconstruction of ancient environments of deposition in nonmarine rocks on the basis of palynologic data, pollen and spores produced by the local flora (plants living near the area in which sediments were deposited) can provide important information, especially on the nature of local environments. This is most true for coal beds, which are usually autochthonous, and which among all ancient deposits have the best chance for preserving a record of the local flora from its pollen and spores. Knowledge of the nature of a coal-forming environment can contribute much to understanding the origin of the coal, its quality, and its significance in paleoclimatology and geologic history.

Disregarding rare occurrences of allochthonous or transported deposits of coal, coal beds represent mires in which vegetation growing on site or in the immediately surrounding area produces the macerals, often including abundant palynomorphs, that compose the peat that is eventually coalifled. In this chapter we use the term mire to refer to wetland depositional environments characterized by accumulation of peat (Gore, 1983; see also detailed discussion of ‘mire’ in Nichols & Pocknall, Chap. 12 this volume); we use the term marsh to refer to wetland environments having aquatic vegetation and organic matter in the sediment, but without accumulation of peat (see Bates & Jackson, 1987). Studies of mires by Quaternary palynologists (e.g., Faegri & Iversen, 1975; Janssen, 1973) demonstrate that palynofloras from such depositional environments more accurately reflect the nature of the vegetation in the area than do those from most other types of sedimentary deposits.