Abstracts

32^nd Annual AASP Meeting, October 1999, Savannah, Georgia, US

SILURIAN PLANT DIVERSITY AS DETERMINED FROM SPORES AND CRYPTOSPORES FROM THE CENTRAL APPALACHIANS, U.S.A.

John Beck and Paul K. Strother

Weston Observatory of Boston College, 381 Concord Road, Weston, Massachusetts USA 02493

The record of Silurian land plant diversity in eastern North America is based on the recovery of spores and cryptospores, non-vascular macrophytes and presumed paleosol root traces. Published reports suggest that this flora was limited to a bryophytic or rhyniophytoid grade of evolution. Palynological and ultrastructural evidence now suggest that pre-Devonian plants in the Appalachian Basin region were more diverse than previously thought.  This report will present ongoing findings in this area of research. From detailed palynological studies from Pennsylvania and Virginia spanning nearly the entire Silurian Period, a minimum of 25 species of spores and cryptospores have been recovered. The sporomorphs are well preserved and comparable to better studied, contemporaneous deposits in Avalonia and elsewhere around the world. Lower Paleozoic taxic plant diversity rose gradually to a peak in the middle Silurian followed by a slight decline in the Ludlow, with diversity increasing rapidly from PrÌdolÌ onward. These findings are consistent with a tripartite succession of evolutionary events seen in the global record of early terrestrial palynomorphs:   

1) a long, Middle Cambrian to middle Wenlock phase dominated by cryptospores but including structurally simple laevigate trilete spores in the Silurian; 2)  a late Wenlock to earliest Devonian transitional phase containing a mixture of sculptured spores and cryptospores; and, 3) the domination of trilete spores during post-Lochkovian time. This pattern may well be a reflection of a mid-Wenlockian origin of tracheids that was followed by speciation in the basal tracheophyte clades.    

The recent work of Charles Wellman, Dianne Edwards and Wilson Taylor has now given us both the ultrastructural and systematic information needed to begin assigning dispersed cryptospores to suprageneric taxa.  Based on palynological information, Silurian plants from the Appalachian Basin are inferred to have included ancestral bryophytes (hepatics and anthocerates), rhyniophytes and  rhyniophytoids, nematophytes, lycophytes, and even sphenopsids. Heretofore, Silurian plant diversity has been cryptic, masked by evolutionarily conservative and poorly preserved vegetative plant megafossils.

IMPACTS OF HISTORICAL LOGGING AND FIRE ON A LAKE SUPERIOR COASTAL WETLAND, KEWEENAW PENINSULA, MICHIGAN

Robert K. Booth and Stephen T. Jackson

Department of Botany, University of Wyoming, Laramie, Wyoming USA 82071-3165

Michigan’s Upper Peninsula was subjected to intense logging and frequent fires in the late 19th and early 20th Centuries. Using paleoecological methods, we investigated the impacts of these historical logging and fire events on a coastal wetland and adjacent upland at Grand Traverse Bay on the Keweenaw Peninsula. The wetland system is characterized by a series of alternating ridges and swales. Swales differ in hydrology, vegetation, and age. Radiocarbon dating indicates that the oldest swales and ridges were formed over ¹⁴C yrs BP. Pollen, plant macrofossils, and charcoal were examined from peat cores recovered from 5 swales (the, 16th, 32nd, 34th, and 49th swales inland from Lake Superior). The upper 15-20 cm of these cores was analyzed at 1-cm intervals, and lower portions of the cores were sampled at coarser (3-8 cm) intervals. Fine-scale pollen and charcoal analyses were also performed on the top 30 cm of a core recovered from a nearby lake (Mud Lake) to provide a regional vegetation and fire record of the uplands for comparison with the Grand Traverse Bay wetlands.

Pollen and macrofossil evidence indicate that the pre-European vegetation of the Grand Traverse Bay wetlands was dominated by Thuja occidentalis, Larix laricina, Picea, and Pinus strobus. Aquatic plants and hydrophytic taxa were also present in the swales, as indicated by Nymphaea pollen and seeds, as well as Carex oligosperma, Dulichium arundinaceum, Scirpus subterminalis, Scheuchzeria palustris, and Potamogeton macrofossils. Macroscopic charcoal occurs in low quantities throughout the pre-European portion of the five swales. A large spike in macroscopic charcoal occurs contemporaneously with the Ambrosia pollen increase, indicating a large historical fire or series of fires in the late th and early 29th centuries. Abrupt changes occur after the fire/fires. Thuja occidentalis becomes locally extinct from the wetlands, and it has not recolonized since. Pollen and macrofossil evidence also suggest widespread expansion of Pinus banksiana, Myrica gale, and Alnus rugosa in the wetland system. Pinus strobus pollen and macrofossils decline above the Ambrosia rise, probably as a direct result of logging.

The microscopic charcoal record of Mud Lake suggests that multiple fires affected the region after European colonization, which is consistent with historical records. However, the pollen record of Mud Lake does not show significant changes in the upland vegetation after these fires. Pre-European and post-European portions of the core are both characterized by abundant Pinus strobus, Pinus banksiana /resinosa, Betula, Picea, and Tsuga pollen.

Results of this investigation suggest that the modern wetland vegetation at Grand Traverse Bay is a result of the late 19th and early 20th Century fires. Lumbering probably influenced the ridge vegetation directly through the extirpation of Pinus strobus. However, it probably indirectly influenced both the ridge and wetland vegetation by the accumulation of slash which increased fire intensity and susceptibility. This increased fire intensity was outside the range of natural variability of the wetland system and the subsequent vegetation response has no similar counterpart in the paleoecological record of the Grand Traverse Bay wetlands. The surrounding uplands were presumably not as sensitive to the logging and fires, or the vegetation-sensing properties of the pollen data are insufficient to detect changes in the regional vegetation mosaic.

ASSESSING ANTHROPOGENIC IMPACTS ON PEATLANDS USING COMBINED PALYNOLOGIC AND PETROGRAPHIC TECHNIQUES

Arthur D. Cohen

Department of Geological Sciences, University of South Carolina, Columbia, South Carolina USA 29208

In peat-containing wetlands, oriented microtome sections can be utilized to supplement and/or fortify paleoecological interpretations derived from pollen analysis. Examples of this approach are presented from two studies, one in the central Everglades of Florida and the other at a Carolina Bay wetland within the Savannah River Site (SRS) in South Carolina. The primary purpose of these two studies was to test this combined method for its usefulness in distinguishing between natural successions and anthropogenically-derived disruptions of the ecosystem (such as diversions of drainage and introductions of contaminants from human sources). Thus, analysis focused primarily on closely-spaced sample increments (every two centimeters) from the upper portions of cores that had been established by Pb-210 and Cs-137 dating to represent approximately the last 100 to 150 years of history.

In the Everglades study, the combined palyno-petrographic method was able to detect with some certainty the first appearance of contaminant-driven plant types into the region, with the petrography being more accurate in determining the actual presence of invading plants (such as, Typha and Lemnaceae) and the palynology providing a broader picture of regional changes in the ecosystem. The correlation of local palynomorph floras (both aquatic macrophytes and algae) with petrographic components indicative of water depth (such as, charcoal and fecal pellets) indicated wetter conditions at all sites prior to human disruption of drainage. The data also suggest that, given sufficient core coverage, pre-disruption drainage patterns and flow directions could be determined.

As in the Everglades study, changes in petrography at the Carolina Bay wetland tended to more accurately reflect local conditions at the specific core site; whereas, palynofloral analysis elucidated the broader paleoecological picture. Palynofacies and petrographic analyses provided additional useful information regarding in situ surface degradation and oxygenation during deposition. Probable anthropogenically-induced hydrologic changes were also identified at the SRS deposit, with the most significant changes occurring at around 1951-52 (coinciding with initiation of SRS construction) and again, to a lesser extent, at about 1984 (coinciding with building of an artificial lake near to and up-gradient from the site).

Owen K. Davis

Department of Geosciences, University of Arizona, Arizona USA 85721

Geoffrey Dimbleby’s 1985 text is a standard reference for archeological palynology. In it, Dimbleby proposes that, "A soil pollen profile is not ... truly stratified (p. 6)." In part, this violation of Nicholas Steno’s Law of Superposition is based on the familiar processes of bioturbation, but Dimbleby departs from well-accepted stratigraphic processes in his application of the process of "downwashing" or "percolation. " The terms are neither defined in the text, nor do they occur in the index. The terms imply the forcing of pollen downward through the soil column by water flow. As used by Dimbleby, the process does not include movement of pollen down animal burrows, root traces, and fissures, because these processes are discussed separately in the text. Dimbleby implies that the pollen is moving as a layer downward through the soil; e.g., "frequencies can increase if the pollen is piling up against a barrier such as an iron pan. " The movement is in one direction, downward, and younger pollen grains are thought to move downward past older pollen grains, and past clastic particles.

"Downwashing" and "percolation" have become accepted stratigraphic processes in the palynological literature; e.g., "Russell attributed the stratigraphy that she observed to progressive downwash of pollen through the mineral soil (PALYNOLOGY 22:166). " Note, the downwash process is said to produce horizonation. Similarly, "Pollen does not stay in the matrix in which it was initially deposited. It is leached downward by percolating groundwater ... (HISTORICAL ARCHAEOLOGY 27:70). "

At issue, in this talk, is the fact that pollen grains (20-60 µm) are too large to move through the pore spaces of soils. Bacteria and viruses (<< 1 µm) are able to do so, slowly. In the waste management literature, 3m of sand is considered an effective barrier to migration of viruses. However the rates attributed to pollen percolation -- 0.33 mm/yr - 1.5 mm/yr – exceed reasonable limits for migration through pore spaces of soils.

I suggest that the continued application of "downwashing" and "percolation" result from palynologists assuming Steno’s Law of Original Horizontality. That is, palynologists assume that a single horizontal soil column represents the stratigraphy of an area. To my knowledge, there have been no studies of sufficient detail to support this assumption. As an alternative hypothesis I propose that Dimbleby’s "other processes" are sufficient to explain the exceptions to normal stratigraphy; that is, movement downward and upward of pollen in animal burrows, root traces, and fissures. If so, evidence for downward movement of pollen should be routinely accompanied by uneven stratigraphy (burrows, traces, and in fissures). This hypothesis fits V.V. Dokukchaev’s1886 definition of a soil, "those horizons of "rock" (quotations mine) which daily or nearly daily change their relationship to joint influence of water air, and various forms of organisms living and dead. " This proposed test would require the analysis of hundreds of pollen samples arrayed in a horizontal grid.

Two corollary observations are that, first, evidence for animal activity should preclude or strongly limit the interpretation of soil pollen profiles as stratigraphic sequences. I accept mixed-species pollen clumps (pollen turds) as evidence of animal activity. Secondly, mixing can be so thorough as to be undetectable in stratigraphic exposure, as demonstrated by "stone lines" in tropical soils.

Thomas D. Demchuk et al. (the Conoco Taiwan Exploration Team)

Conoco Inc., P.O. Box 2197, Houston, Texas USA 77252-2197

As part of Conoco's exploration activities in the Taiwan Straits, the bio- and chronostratigraphy of the region were re-evaluated. This was done to aid in determining basin histories through tectonic and structural reconstructions, source rock identification, maturation and basin modeling, stratigraphic (reservoir) architecture and seismic facies analyses. Earlier biostratigraphic work conducted by the local host company consisted solely of calcareous nannofossil analyses. The recent project utilized new micropaleontological data from twelve wells through the Taiwan Straits, representative of the various interpreted structural and depositional regimes, in order to construct a regional chronostratigraphic framework.

Biostratigraphic analyses of the twelve wells included detailed palynology, with accessory foraminiferal and calcareous nannofossil analyses to enable correlation to earlier determinations and worldwide chronostratigraphy. Further detailed biostratigraphic data were obtained from four exploration wells drilled in early 1998. Detailed, integrated biostratigraphy identified early Miocene strata of marine and marginal marine origin, overlying undifferentiated early Miocene and Oligocene fluvial-lacustrine strata. The exact nature of the Oligocene-Miocene boundary is equivocal (conformable?). Undifferentiated Oligocene strata are interpreted as unconformably overlying middle Eocene through late Paleocene marine strata. The extent of the hiatus between the Oligocene and Eocene cannot be definitely dated, other than for the interpreted absence of late Eocene strata. The identification of a thick Oligocene section is unique. Previous work on these strata had referred to them as "barren", i.e. barren of calcareous microflora, with little other documentation. Palynological investigations, however, identified a monospecific dinoflagellate/algal assemblage with minor pollen and spores, interpreted as lacustrine. These dinoflagellates along with the pollen and spores (Cicatricosisporites dorogensis assemblage) allowed for correlation to Oligocene strata of the Bohai Basin to the north. Further, recognition of these unique Oligocene lacustrine strata indicated reworking of the middle Eocene (NP16-NP17) calcareous nannofossils which may have earlier led to erroneous stratigraphic interpretations, correlations and basin evolutionary models. Definitive middle Eocene strata (NP14-NP15 correlative) are confirmed through the presence of a cosmopolitan dinoflagellate assemblage dominated by Diphyes colligerum, along with interpreted in situ calcareous nannofossils and planktonic foraminifera.

INTEGRATION OF EVENT PALYNOSTRATIGRAPHY WITH SEISMIC FACIES ANALYSES AND SEQUENCE STRATIGRAPHY, CENOZOIC STRATA OF THE TAIWAN STRAITS REGION (POSTER)

Thomas D. Demchuk et al. (the Conoco Taiwan Exploration Team)

Conoco Inc., P.O. Box 2197, Houston, Texas USA 77252-2197

Integration of varied micropaleontological data has led to a new interpretation of the Cenozoic strata from the Taiwan Straits region. The development of a well-defined chronostratigraphic framework, paleoenvironmental determinations and integration with sequence stratigraphy and seimic facies analyses have led to a thorough understanding of depositional architectures and exploration opportunities. Palynological and other detailed micropaleontological data are available from 16 wells throughout the region, including detailed information from four exploratory wells drilled in early 1998. Previous chronostratigraphic interpretations from the area relied solely on calcareous nannofossils and were tied closely to lithostratigraphy.

A series of palynological datums was identified which were integral in the interpretation of seismic facies. These datums correlated extremely well with seismic events, and were critical in understanding and correlating seismic horizons. The identified palynological datums included:

• an early Miocene diverse dinoflagellate assemblage corroborated by calcareous nannofossils and planktonic foraminifera, representing marine inundation of the Taiwan Straits regions during these times;
• a sharp downhole reduction in marine microflora corresponding to an increase in pollen and spores, interpreted as a product of early Miocene marginal marine and fluvial-deltaic sedimentation;
• an increase in ceratioid/peridinioid dinoflagellates or freshwater algae (Pediastrum/Botryococcus) of lacustrine origin, interpreted as Oligocene in age and representing a tectonic reorganization of the general region. A seemingly conformable Oligocene-Miocene boundary may be identified by the first downhole occurrence of Cicactricosisporites dorogensis. A reworked middle Eocene (NP16-NP17) calcareous nannofossil assemblage is interpreted within the lowermost part of the idenitified Oligocene section. Late Eocene strata are not present in the Taiwan Straits region;
• a sharp decline in lacustrine algae and a corresponding increase of in situ marine dinoflagellates interpreted as early to middle Eocene in age. This is corroborated by an in situ NP14-NP15 and younger age calcareous nannofossil assemblage, and;
• a late Paleocene-earliest Eocene downhole decrease in marine palynoflora, and increasing lacustrine algae (Pediastrum and/or Botryococcus) corresponding to syn-rift lacustrine source rock facies (not present in all basins).

C. N. Denison and R. A. Scheppy

Chevron Overseas Petroleum, Inc., P.O. Box 6046, San Ramon, California USA 94583-0746

Relationships between depositional environments and microplankton populations from outcrop samples provide valuable insights that can be applied to the facies interpretation of core through hydrocarbon reservoirs. Some insights and pitfalls are illustrated using an incised valley-fill outcrop succession at Tuscher Canyon, and a synthetic core that represents the succession as if it had been cored immediately behind the outcrop face.

Outcrop weathering essentially excludes sandstones as worthwhile candidates for sampling. Alternatively, core samples of very fine- through medium-grained sandstone can produce palynomorphs, although they may be sparse. Potentially productive siltstones and mudstones at outcrop can be deeply recessive and a weathering rind may effect sample quality, whereas fresh material in core can be sampled easily.

A more far-reaching difference is in lateral continuity of depositional facies. Tuscher Canyon provides ~1 km strike section through a complex incised valley fill. In the heterolithic fill, predominantly arenaceous lithologies unsuitable for palynology can be avoided by moving laterally along the outcrop, to an interval of finer grained lithologies. Samples of the most suitable lithologies are thereby maximized. In contrast, cores samples are limited to a section width of 15 cm or less and are generally taken in sandstone dominated successions that give maximum sedimentological and engineering data. This results in a sample bias due to unfavorable sampling media. For palynological purposes, the advantages of fresh unweathered rock found in core are outweighed by the predominance of unsuitable lithologies.

At Tuscher Canyon, 15 siltstone/mudstone samples were collected to aid in analysis. Samples were sieved at 20 microns to concentrate the relatively large microplankton. Although most populations are small, the presence of any quantity of known species of euryhaline/marine dinocysts e.g. Spiniferites) are significant because they indicate persistent conditions of low salinity, or at least brief periods of saline influx. One sample at the base of the incised valley-fill, immediately above the sequence boundary, produced over a hundred dinocyst specimens, mainly Spiniferites and an undescribed trabeculate species, with rare Oligosphaeridium and Isabelidinium. This assemblage indicates marine influence (saline conditions). Both laterally and vertically, however, recovery drops to a few dinocyst specimens, with the hardy Spiniferites being the most consistent component. Stratigraphically higher in the section, but still along strike within the valley fill, a sparse assemblage consisting entirely of 'Campenia' suggests an areally restricted, stagnant lagoon or marsh. Samples collected even higher in the section, in the upper part of the incised valley-fill, yielded no microplankton, reflecting the lack of marine influence. Samples collected from the outcrop indicate three separate depositional facies, some with substantial lateral variability: (1) marine influenced mud/siltstones; (2) marine influenced marsh siltstones; (3) non-marine mudstones.

O. F. Dzyuba, T. L. Jakovleva, and A. N. Kudrina,

IC Bioecological, St. Petersburg, Russia

The pollen of arboreal plants and grasses from various districts near St. Petersburg, the atomic power station satellite-town of Sosnovyi Bor, and the Chernobyl Atomic Power Station security zone was investigated. It was revealed that in all the plant species we investigated and that were under the influence of industrial emissions, a great number of teratomorphical pollen grains exists (up to 100%). The changes concern even exine sculpture and structure - the most stable structures of pollen grains. Furthermore, the stronger the influence of the industrial emissions, the more more significant are the changes that have occured in pollen grain morphology.

Results of sperm inspection of wild and domesticated animals that have lived constantly in the same towns and their suburbs confirm the results of the pollen grain inspections: a gametopathogenical hazard exits in the area of investigation. It exists not only for plants, but also for animals, and it reaches its maximum in those Saint Petersburg districts with the most unfavourable ecological conditions and in the Chernobyl Atomic Power Station satellite town of Sosnovyi Bor. Humans occupy a significantly more stable environment than other organisms and their generative system is vastly better protected from external influences. Nevertheless, as a result of volunteers’ sperm examination, some tendency to decreased fertility is revealed in men involved in hazardous occupations as compared to those who were not similarly occupied. According to spermatograms, in 36% of men examinated such a tendency was revealed.

As can be seen from this study, the higher plants’ pollen morphology can serve as a model for monitoring reproductive changes in plants, animals and humans.

Donald W. Engelhardt¹ and Robert S. Van Pelt²

¹Earth Sciences and Resources Institute, University of South Carolina, Columbia, South Carolina USA

²Bechtel Savannah River, Inc., Savannah River Site, Aiken, South Carolina USA

Freshwater dinoflagellate cysts comparable with Peridinium limbatum (Stokes) Lemmermann have been recovered from cores from Peat Bay, a Carolina Bay, on the Savannah River Site in Barnwell County, South Carolina. P. limbatum and other peridinioid cysts were observed in several samples taken from the two peat cores analyzed during the study of the paleoecology of this Carolina Bay. The onset of peat accumulation in Peat Bay has been dated as approximately 4000 years B.P. Carolina bays are surficial depressions that are not of marine origin that occur in large numbers throughout the Atlantic Coastal Plain. Their origin is not completely understood, but the most accepted theory is that they are aeolian features formed and oriented by paleo-wind currents during the late Pleistocene (Kaczorowski, 1977; Bliley and Burney, 1988).

Palynologically, the dinoflagellate cysts occur mainly during hydroperiods that are dominated by floating aquatics, Myriophyllum, Nymphoides, and Nymphaea. Botryococcus is present along with zygospores or aplanospores of Spirogyra, Zygnema, and Mougeotia. Numerous statospores of genera of the Chrysophyceae, chrysomonads, along with abundant diatom taxa occur in conjunction with the dinoflagellates.

Donald W. Engelhardt¹ and Robert S. Van Pelt²

¹Earth Sciences and Resources Institute, University of South Carolina, Columbia, South Carolina USA

²Bechtel Savannah River, Inc., Savannah River Site, Aiken, South Carolina USA

Palynology has been and is currently being applied in combination with other geologic disciplines to establish the subsurface hydrogeological framework for environmental restoration activities at the Savannah River site. The Savannah River Site (SRS) occupies 310 square kilometers in southwestern South Carolina. The Late Cretaceous through Recent aged Coastal Plain sediments underlying the site constitute the hydrologic system beneath the SRS and surrounding area. Palynology has been used from the mid-1980’s to the present as a basis for revising the formal stratigraphic column. In general, the age determinations based on palynology allow for more accurate correlations of the stratigraphic units in the southeastern Coastal Plain, in what is considered the Floridan Aquifer System.

Numerous Tertiary core samples from the aquifer and confining units in the SRS area have been analyzed for dinoflagellates, pollen, and spores. These units can be described in terms of their age-diagnostic and environmentally characteristic dinoflagellate assemblages and the highest and lowest occurrences of selected pollen and spores. This study attempts to integrate and synthesize the reported palynomorph occurrences in consultant reports, published data and observations into first appearance datums (FAD’s) and last appearance datums (LAD’s) for the Early Tertiary sequence (Paleocene to Late Eocene) present in the SRS area. These datums are related to geologic formations and age determinations based on other fossil groups.

John V. Firth

Ocean Drilling Program, 1000 Discovery Drive, College Station, Texas USA 77845

Maastrichtian sediments recovered in the USGS Santee Coastal Reserve Borehole, Charleston, SC, and ODP Site 1052 at 1343.5 m of water on the continental slope of the Blake Nose, provide an onshore-offshore transect across the southeastern U.S. continental margin. These cores contain diverse dinoflagellate cyst assemblages which can be calibrated to calcareous nannofossil and planktonic foraminifer biostratigraphy, and to magnetostratigraphy. Biostratigraphically useful species in these sections include Xenascus ceratioides, Andalusiella spicata, Alterbidinium acutulum, Deflandrea galeata, Isabelidinium cooksoniae, Thalassiphora pelagica, Disphaerogena carposphaeropsis, and Palynodinium grallator.

The USGS Santee Coastal Reserve Borehole contains high abundances of dino cysts, with assemblage changes between those dominated by Glaphyrocysta and Areoligera and those dominated by peridinioid species such as Cerodinium, Senegalinium, Phelodinium, and Andalusiella. Some samples contain mixed assemblages which are not dominated by any one species or group. ODP Site 1052 shows large fluctuations in the absolute abundance of dinoflagellate cysts/gm, and contains assemblages which vary from being dominated by Exochosphaeridium and Glaphyrocysta to those dominated by a leiosphere-like cyst. Reworking is suggested by the stratigraphic ranges of some species, which corroborates other microfossil data, as well as sedimentological and geophysical data that shows slumping within the Maastrichtian slope sediments.

MARINE PALYNOMORPHS CONFIRM SEQUENCE BOUNDARIES

ESTABLISHED FOR THE SWISS BASIN

Ebrahim Ghasemi-Nejad

Dept. of Geology, Faculty of Science, University of Tehran, Enghelab Street, Tehran, Iran

During the Middle Oxfordian time a carbonate platform was established in the northern Switzerland sedimentary basin which persisted till Kimmeridgian . Eight 3rdorder sedimentary cycles, together forming a 2nd order regressive-transgressive cycle have been recognized to represent the whole of Oxfordian sediments. Transgression started with a decrease in terrigenous influx and progradation of the carbonate facies across the carbonate platform. Renewed influx of terrigenous sediments marked the regression and termination of coral reef growth. Condensation of the beds, and deposition of a condensed fossiliferous horizon in the basin characterized maximum flooding. Changes in color, fossil fauna (especially ammonites), and lithology have been used for determination of the sequence boundaries. Marine palynomorphs, especially dinoflagellates, their absolute abundance, variation and relative abundance have been studied and statistically analyzed to see whether or not these microorganisms can help to confirm the determination of sequence boundaries.

The four first boundaries (O1 - O4) are boldly marked by sharp decreases in the number of dinoflagellate species preserved in rock samples. However, two other similar decreases appear through the stratigraphic column if one plots the number of species versus sample number; these have not been reported previously as boundaries. They may reflect the more sensitive nature of marine palynomorphs to environmental changes, as compared to other organisms such as ammonites, brachiopods and bivalves.

Marine palynomorphs, therefore, seem to help greatly not only for confirming the sequence boundaries already marked via other characteristics mentioned above, but also may mark new boundaries that could have not been recognized by using other characters.

L. Dillon Gorham and Vaughn M. Bryant, Jr.

Palynology Laboratory, Texas A&M University, College Station, Texas USA 77843-4352

Our preliminary pollen analysis of sediment samples and deposits inside amphora vessels found in two A.D. ninth-century shipwrecks are providing useful clues as to the contents of the ship's cargo. One of the shipwreck sites is located in Tantura Lagoon approximately 25km south of Haifa, Israel. The second sampled shipwreck was discovered near Bozburun, Turkey, on the southwestern coast of the Anatolia region.

Our study demonstrates that pollen analyses are possible from these types of sites, and that additional fossil pollen studies should be continued for both of these sites as well as other similar shipwreck sites. Initial pollen and seed identifications from the amphoras reveal that part of both sunken ships' cargoes consisted of foods and other agricultural products. Based mainly on fossil pollen, and supported in some cases with recovered seeds, we are able to identify the following economic products as being probable cargo goods: 1) olives or olive oil; 2) grapes, raisins, or grape wine; 3) pine pitch; 4) various types of spices; 5) sumac; 6) cereal grains; and 7) possibly dates and plums.

Non-economic pollen types (pine, oak, hickory, willow, grass, composite, etc.) found during this study offer a few clues that might provide a key to determining each ship's home port, or other ports where each ship loaded or unloaded cargoes. Nevertheless, the majority of the fossil pollen recovered from both shipwreck sites reflects economic products that were undoubtedly being carried as part of the ship's cargo at the time each sank.

C. Heunisch¹ and U. ²

¹Niedersächsisches Landesamt für Bodenforschung, Stilleweg 2, D-30655, Hannover, Germany

²Geologisch-Paläontologisches Institut der Universität Münster, Corrensstr. 24, D-48149, Münster, Germany

The Triassic strata in the north and the northeast of the Rhenish Massif from Osnabrück to the Lippe upland, NW Germany) were investigated with respect to lithofacies and palynofacies. The lithofacies and palynofacies of the lagoonal to hypersaline facies at the Röt/Lower Muschelkalk boundary, the hypersaline red beds of the Middle Muschelkalk succession, and the hypersaline Gelbe Basisschichten of the Upper show a considerable correspondence. The same is true of the brackish and brackish to continental environments of the Lower Muschelkalk, Dolomitische Grenz-schichten (Upper Muschelkalk), Lower Keuper and the upper parts of the Middle Keuper. The lithofacies and palynofacies data are mutually complementary with respect to paleoenvironmental interpretation. The cyclic sebkha/ephemeral lake sedimentation of the Lower Gipskeuper is reflected in the palynology in the same way as the limnic to deltaic facies of the Rhaetian.

Gretchen D. Jones

USDA-ARS, APMRU, 2771 F&B Rd., College Station, Texas USA 77845

Pollen analyses were used to determine alternative foraging resources of adult Mexican corn rootworms, Diabrotica virgifera zeae, captured in 1997, near Temple, Bell Co., TX. Overall, 94% of the Mexican corn rootworm adults (n = 617) contained pollen, and over 46,000 pollen grains were counted. Mexican corn rootworm adults contained more non-corn grass pollen (71%) than any other type. Non-corn grass pollen also occurred in the greatest percentage of samples (74%). Pollen from 37 families, 45 genera, and 22 species was identified in the samples. Fifteen Asteraceae pollen taxa were encountered including aster (Aster sp.) and sunflower (Helianthus annuus C. Linnaeus). Following Asteraceae was the Fabaceae with 13 taxa including soybean (Glycine max C. Linnaeus) and alfalfa (Medicago sativa C. Linnaeus). Although Mexican corn rootworm adults foraged mainly on grass pollen (family Poaceae), they also foraged on pollen from a diversity of plant species. This diversity of alternative foraging resources indicates that alternative food sources play an important role in food sources of Mexican corn rootworm adults.

Gretchen D. Jones¹and Wayne G. Buhler²

¹USDA-ARS, APMRU, 2771 F&B Rd., College Station, Texas USA 77802

²Pesticide Education Specialist, North Carolina State University, Raleigh, North Carolina USA 27695-7609

Adult western corn rootworms (Diabrotica virgifera virgifera Le Conte) occur in Illinois corn fields from July until frost, feeding on corn (Zea mays C. Linnaeus) foliage, pollen, silks, and immature kernels. The larvae feed on the roots of corn plants. Damage to corn roots weakens the plant by reducing the plants ability to absorb water and nutrients. It was thought that the larvae could not survive on roots of crops. Therefore, the most effective method for corn rootworm management was to rotate corn with soybean, (Glycine max C. Linnaeus), sorghum [Sorghum bicolor (C. Linnaeus) C. Moench], forage grasses such as johnson grass [S. halepense (C. Linnaeus) C. Persoon], or wheat (Triticum aestivum C. Linnaeus). In the early 1990’s, corn rootworm damage was reported in corn grown in fields where soybeans were planted the previous year. Pollen analyses were used to determine pollen feeding of western corn rootworm adults collected in Benton and Jasper Cos., Indiana. Collection sites consisted of five pairs of fields; each field pair consisted of a corn field and an adjacent soybean field. Insects were collected twice a week from 18 June - 8 August 1997, in the middle and the end of each field. The results of a single pair of fields, field 5, are reported. A total of 926 insects were examined, 463 captured in corn, and 463 in soybeans. Overall, 4,711 pollen grains were counted. Insects captured in corn contained more pollen grains (3276) than those in soybeans (1435). However, the pollen diversity was greater in insects from soybeans (40) than corn (32).

Gretchen D. Jones¹and Dick D. Hardee²

¹USDA-ARS, APMRU, 2771 F&B Rd., College Station, Texas USA 77802

²USDA-ARS, SIMRU, Stoneville, Mississippi USA 38776

Pollen analyses were used to determine foraging resources of adult boll weevils, Anthonomus grandis Boheman, captured from March 1996 through January 1997 near Elizabeth (Washington Co.), Mississippi. Overall, 87% of the samples (n = 821) contained pollen. Over 41,200 pollen grains were counted. Pollen representing 82 families, 132 genera, and 29 species was identified in the samples. The North Site samples contained significantly more pollen grains and taxa than other sites (ANOVA, F = 2.042, 5.518; df = 817, 817, P < 0.001, 0.001, respectively). Boll weevils collected from April through June, and August through October contained significantly more taxa than those collected during other months (ANOVA, F = 15.50, df = 820, P < 0.001, Tukey's). Asteraceae (21) contained more pollen taxa followed by Fabaceae (14). Pollen from Asteraceae (62%), Malvaceae (6% ), and Anacardiaceae (6%) represented the highest percentage of pollen grains; whereas, Asteraceae (67%), Poaceae (45%), and Anacardiaceae (39%) pollen were found in the greatest number of samples. There were no significant differences in species diversity and richness among the sites (ANOVA, F = 0.827, 0.577, df = 54, 54, P = 0.514, 0.681, respectively); nor was there any significant difference in species evenness among the sites or among the months (ANOVA, F = 0.763, 1.472, df = 54, 54, P = 0.554, 0.182, respectively). However, species diversity was significantly less during March and January, and species richness was significantly less during March, July, December, and January (ANOVA, F = 3.408, 6.521, df = 54, 54, P = 0.002, <0.001, respectively). This research shows that boll weevils foraged on a variety of pollen throughout the year.

R. Kalgutkar and J. Jansonius

Geological Survey of Canada, Calgary, 3303-33 Street NW, Calgary, AB, Canada T2L 2A7

In this Synopsis we bring together some 940 validly published names of species, attributed to some 230 genera (not including some 70 names of extant genera, nomina nuda, and junior synonyms and homonyms). We propose twelve new genera:

Axisporonites, Biporisporonites, Disparidicellites, Hilidicellites, Kumarisporites, Mathurisporites, Mossopisporites, Multicellites, Ramasricellites, Saccisporonites, Trihyphites and Varmasporites. We also propose one new species: Ctenosporites sherwoodiae. Transfers of species to more appropriate genera resulted in 31 junior homonyms, for which we provided the following nomina nova: Dicellaesporites largelongatus, D. perelongatus; Dictyosporites paradkarii; Didymoporisporonites gigas; Diporicellaesporites macellus, D. minifusiformis; Diporisporites pergranulatus; Dyadosporites antarcticus, D. neoconstrictus; Fusiformisporites duenasii; Hilidicellites dubius, H. trivedii; Hypoxylonites kumarii; Inapertisporites clarkei, I. edigeri, I. neopunctatus, I. triporitus; Kutchithyrites canadensis; Monoporisporites doubingerae, M. mathurii, M. nemagnus, M. neoglobosus, M. perpsilatus, M. singularovalis; Multicellaesporites? songii; Pluricellaesporites cooksoniae, P. edigeri, P. malevisus, P. mexicanus; Scolecosporites modicus; Staphlosporonites billelsikii. Some names of species, not validly published in their protologue, are here validly published "ex Kalgutkar & Jansonius": Biporipsilonites bellulus (Ke & Shi), Cercosporites torulosus (Trivedi & Verma), Dicellaesporites longus Trivedi & Verma, Diporisporites planus Martinez-Hernandez & Tomasini-Ortiz, Microthyriacites baqueroensis Martinez, Palambages colonica Trivedi & Verma, Pluricellaesporites dentatus Trivedi & Verma, P. minutus Trivedi & Verma and P. planus Trivedi & Verma. Our transfers also resulted in some 350 new combinations: too many to list in this abstract. While we tried to include all papers of interest particularly to palynologists, this Synopsis will provide benefit to mycologists who find the literature on fossil remains not easily accessible. The latter also may appreciate a brief survey of megascopic remains reported in the literature. Still, we did not access many of the earlier (nineteenth century) publications.

We give an introduction into paleomycology, as well as some mycological fundamentals, for palynologists; a brief section on palynological practices may benefit mycologists. Technical terms are explained in a glossary. The main part of this Synopsis is the systematics section, where the full descriptions of genera and species are given in alphabetic order; junior synonyms and homonyms are included, with cross-references to new combinations or names. The types of most species are illustrated with a line drawing.

Joyce Lucas-Clark¹ and Lucy E. Edwards²

¹Clark Geological Services, 1023 Old Canyon Rd.

Fremont, California USA 94536

²U.S. Geological Survey, Reston, Virginia USA 20192

Two lineages of fossil dinoflagellate cysts comprise a set of index species for the southeastern United States, particularly in South Carolina, Georgia, and Alabama. The Gonyaulacaceae genus Pentadinium and closely related species ancestral to it (Hafniasphaera goodmanii and H. septata) evolved through the Paleocene, Eocene, Oligocene, and Miocene. The Peridiniaceae genus Wezeliella and genera ancestral to and descendant from it (Apectodinium and Charlesdowniea) evolved through the Late Paleocene, Eocene, and Oligocene. Species of the two lineages are common to abundant throughout much of Southeastern USA. First and last occurrences of the species can be used to establish relative dates on strata. Paleoenvironments of most of the datable strata are delta plain and adjacent shallow marine settings.

PROFILE PATTERNS AND THEIR PALEOECOLOGICAL INTERPRETATION IN THE HERRIN (NO. 6) COAL MEMBER AT OLD BEN NO. 24 MINE (FRANKLIN COUNTY, ILLINOIS)

James F. Mahaffy

Biology Department, Dordt College, Sioux Center, Iowa USA 51250

Two miospore profiles and lateral sampling of the Herrin Coal member (Carbondale Formation, Middle Pennsylvanian) from Old Ben 24 Mine are used to study intraseam vegetational changes and patterns of lateral variation at different levels of the seam. The palynological changes are also compared to patterns of changes in vegetative matter preserved as macro-fossils in coal-balls at the same locality.

Although the miospore flora at Old Ben 24 is more uniform than other Carbondale coals (like the Springfield) and even other localities in the Herrin, the same vegetation stages could be distinguished in two seam profiles separated by 381 meters. Both seam profiles can be divided into three major sections. Each of these sections, in turn, can be subdivided into smaller zones or vegetation phases that are traceable in both profiles. The two lower sections of the coal seam are both dominated by Lycospora at about 50% abundance. A clastic parting, "the blue-band", physically separates the lowermost from the middle section.

Lateral variation at one locality is documented by comparing amounts of individual miospores in the two profiles. Many miospore taxa show very similar changes in abundance at the same level of the seam. Patterns of Lycospora are very similar at the two sites (R2 = 0.79669 with linear regression). Patterns of combined tree-fern (Psaronius) are also similar, but with different tree fern miospores abundant in each profile. The top coal zone (high in Diaphorodendron, and Endosporites globiformis) is distinctive showing the most variation between profiles.

Changes in miospore abundance were also correlated with changes in lithotype of the coal and with five preservation categories of the miospores (excellent to very poor). Changes in spore preservation often occurred when major miospore changes took place, resulting in some vegetational phases of distinctively poor spore preservation, while others in the same profile showed excellent preservation.

Distribution patterns of some of the plants within a coal swamp can be deduced by comparing patterns within spore profiles and coal-ball profiles. Some of the plants appear to have formed scattered stands in the swamp, while others were randomly distributed throughout most of the coal-swamp vegetation.

E. Martínez-Hernández and E. Ramírez Arriaga

Instituto de Geología, Depto. de Paleontología, Ciudad Universitaria 04510, Coyoacan, México, D.F.

The undifferentiated Cenozoic beds in the Tepexi De Rodriguez region have yielded valuable palynological assemblages ranging in age from Paleocene to Oligocene. Initially, the Tertiary sequence was considered as Pliocene-Pleistocene based on mammal tracks at the Pie de Vaca locality. This confusion increased due to the presence of Quaternary sediments with horses, glyptodonts and mammoths that uncorformably overlie the Pie de Vaca Formation.

Initially, the palynological assemblages indicated an abundance of certain taxa such as Pinus sp. and grasses that characterize the Quaternary of Central Mexico. However, the significant evidence of Plio-Pleistocene tracks in the region suggests that the initial palynological results support a Pliocene-Pleistocene age, although the possibility of a Neogene age for the Cenozoic sequence was never discarded.

The discovery of Cedrelospermum and Eucommia, taxa that occur in the Lower Tertiary of North America, has once again brought up the question of age assignment of the Cenozoic rocks in this region. This issue prompted a new palynological study of the volcaniclastic sequence, based upon the total pollen content and distinction of different kinds of biozones. That work finally allows the palynostratigraphical assignment of the beds to the Eocene.

The palynological assemblages indicate that during the Paleogene several plant communities were present locally and regionally, forming different mosaics of vegetation that were distributed along an altitudinal gradient. Regionally, the forest of conifers (Picea and Pinus) occupied the mountain ranges, together with abundant grasses and Ephedra spp., where the climate was cold-temperate. In contrast, the slopes of hills were more humid with temperate to subtropical climate with a mesophytic community characterized by the abundance of Engelhardtia (Momipites spp.), Cedrelospermum, Eucommia, Betula, Ulmus, Juglans and Platanus. Near the depositional basin, the climate regime became subtropical and drier, with an abundance of legume fruits and abundant pollen of Caesalpinea, Mimosaceae, Bombacaceae, Burseraceae, grasses, and Ulmaceae, which could indicate savannah to scrubland vegetation. The previous vegetational types should be considered as a models since it is clear that vegetational types are distinguished because of their physiognomic pecularities and not because of their taxonomic composition. Supporting the interpretation of this mosaic of vegetation is the fact that in the macrofossils the conifer remains are rare and the leaves that predominate in the florule are rather small, indicating that the vegetation growing near the site of deposition was subject to a dry subtropical regime.

In spite of the presence of grasses, but based upon the chronostratigraphic relevance of certain taxa such as Pterocarya, Erdtmanipollis, Aglaoreidia , Pandanus and several Momipites spp., the age of the assemblage is considered to be uppermost Eocene. Furthermore, the presence of freshwater algae and the pollen of Aglaoreidia and Pandanus confirm the palustrine and coastal paralian lacustrine environment of these beds. The pollen appear to have affinities with the Tertiary floras of the Rocky Mountains.

HIGH-RESOLUTION PALYNOLOGY OF A MARINE CORE FROM SAANICH INLET, BRITISH COLUMBIA

Rolf W. Mathewes and Marlow G. Pellatt

Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6

Saanich Inlet is a near-shore anoxic basin with laminated sediments that were cored as part of Ocean Drilling Project Leg 169S. One of the cores (1034B) was studied palynologically at approximately 25-year intervals and dated by varve counting and radiocarbon analysis. Results were compiled in standard pollen per centage diagrams and also as an influx (pollen accumulation rate) diagram for the Holocene portion. Using constrained cluster analysis, the diagram was divided into six pollen assemblage zones or subzones. The zones correspond well to previous biostratigraphic schemes and climatic reconstructions based on pollen analyses of regional lakes. Of particular interest are some rapid changes, such as the sudden

increase in per centages and influx values of oak (Garry Oak) around 7500 yr BP (uncalibrated age). This event indicates formation of oak woodland, replacing a more open vegetation with abundant grass and bracken fern, probably under a wetter climate. Another rapid change is the sudden increase in Cupressaceae (mostly western redcedar) pollen around 4900 yr BP, which also suggests increased wetness and perhaps neoglacial cooling. Both the above changes were rapid for forested landscapes, probably taking less than 100 years to complete.

At 10,000 yr BP, at the Pleistocene/Holocene transition, two massive beds of clay-rich sediment were deposited. Total pollen accumulations are relatively low, and palynological analysis reveals abundant reworked Tertiary pollen and spores. Preliminary analysis indicates the presence of Paleogene to Miocene types, including true cedar, hickory, linden, walnut, and others. These assemblages and their associated age and lithology suggest that a catastrophic flood may have eroded Tertiary rocks following the breaching of ice dams during deglaciation. Floodwaters rushing down the Fraser River, east of Saanich Inlet, are the most likely source of the Tertiary pollen and spores, which likely came from sedimentary rocks underlying the present Fraser River Delta.

Francine M.G. McCarthy, Kevin E. Gostlin, and Jennifer Hopkins

Department of Earth Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1

A major objective of ODP Leg 174A was to investigate how sea level change affects sedimentation on continental margins, and, more specifically, to test the concept that sequence boundaries result from glacioeustatic fluctuations. Palynological data were used to reconstruct the sea level and climatic conditions associated with the generation of inferred sequence boundaries in Quaternary sediments on the New Jersey margin defined by the Leg 174A Scientific Party. The palynological character of surfaces identified as sequence boundaries from seismic reflection profiles records the generation of erosional unconformities during extreme lowstand events. Lowstands altered the geometry of the margin, and were followed by rapid transgressions. Erosional unconformities are characterized by very low palynomorph concentrations and oxidized palynological assemblages (containing few protoperidinioid dinocysts or thin-walled pollen grains). The strong seismic reflection associated with sequence boundaries results from physical contrasts between the transgressive sediments (with very high palynomorph concentration, P:D values declining rapidly upcore, and Pinus-dominated pollen assemblages) and the underlying lowstand sediments (with low palynomorph concentration, high P:D values, taphonomically altered and ecologically mixed palynological assemblages) on which the erosional unconformities were generated. The palynological content of Quaternary sediments at ODP Sites 1072 and 1073 thus supports the role of eustasy as an important factor in shaping the New Jersey margin, although other factors, such as sediment influx are also important.

WHAT DO PALYNOLOGICAL RECORDS RECORD?

Francine M.G. McCarthy¹, Peta J. Mudie² and Kevin E. Gostlin¹

¹Department of Earth Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1

²Geological Survey of Canada - Atlantic, Box 1006, Dartmouth, Nova Scotia, Canada B2Y 4A2

The presence of both marine and terrestrial palynomorphs in virtually all marine sediments makes them potentially valuable paleoenvironmental and biostratigraphic markers, particularly in neritic and high latitude environments where other microfossils are scarce. It may be possible to reconstruct sea surface conditions from the dinocyst record and to directly correlate between land and sea using the pollen record. However, this potential can only be realized if the palynological assemblages preserved in the sediments accurately reflect environmental conditions that existed in the overlying ocean waters and on the adjacent landmass. Every palynological assemblage is skewed, relative to the actual vegetation and plankton, by taphonomic factors, such as differential transport and preservation of palynomorph taxa. If taphonomic alteration is not thoroughly accounted for, erroneous paleoenvironmental reconstructions will result. When recognized, taphonomic complexity can be accounted for in reconstructing paleoenvironments, and can also be exploited to extract geological information about sedimentation. Comparisons between modern palynomorph distributions and Quaternary records in the North Atlantic ocean illustrate the impact of taphonomy on the paleoenvironmental signal, and reveal the additional sedimentological and stratigraphic information that can be obtained by understanding the taphonomic impact.

CONTROLS ON PALYNOMORPH DISTRIBUTION IN THE NORTH ATLANTIC FROM THE MIOCENE TO THE RECENT (POSTER)

Clayton R. Morgan¹ and Francine M.G. McCarthy²

¹School of Geography and Geology, McMaster University, Hamilton, Ontario, Canada L8S 4M1

²Department of Earth Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1

We need to understand ocean processes and patterns in order to better predict, and prepare for, changing climates. Changes in palynomorph distribution through time reflect changing biological, physical and chemical oceanographic processes such as productivity, current patterns and sediment deposition. Terrigenous (pollen and spore) and marine (dinoflagellate) palynomorphs in marine sediments are used to reconstruct past terrestrial and marine conditions. The ratio of pollen and spores to dinoflagellate cysts (P:D) is employed in studies of ocean sediment and deposition systems because wind is the main mechanism of terrestrial palynomorph transport while dinocyst (dinoflagellate cyst) distribution is closely associated with water masses. Very high P:D ratios correlated with late Pliocene-Pleistocene glacioeustatic lowstands in North Atlantic deep-sea cores reflect increased terrigenous sediment influx to the mid-latitude abyssal North Atlantic Ocean.

Geographic Information Systems is an excellent means to map palynomorph distribution patterns. By mapping pollen/spore and dinocyst spatial distribution in marine sediments for various time slices over the Neogene to Recent, we attempt to identify paleoenvironmental and taphonomic controls on palynomorph distribution. Time slices are calibrated using calcareous nannofossil and magnetostratigraphic zone boundaries, which are established and well-dated. Multivariate analyses will be employed to study these changing relationships related to identified influencing factors such as changes through time in ocean and atmospheric circulation patterns, sediment accumulation rates, sea level, etc., which are associated with a changing climate. Increased knowledge of the distribution of palynomorphs and their responses to paleoenvironmental and taphonomic controls will allow us to more effectively predict affects of climate change on oceanographic processes.

Peta J. Mudie¹, Andre Rochon² and Elisabeth Levac2

¹Geological Survey of Canada©Atlantic, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada B2Y 4A2

²Centre for Marine Geology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5

Historical records document the occurrence of red tides for the past 3,000 years and show apparent increases during the past 50 years on both East and West coasts of Canada. Laboratory and field observations over the past 20 years suggest that blooms of toxic (PSP) Alexandrium and Gonyaulax species are often stimulated by warm sea surface temperature (SST) and high river runoff, but laboratory results are variable. Longer (10,000 years) records from Holocene sediments may provide some insight into the apparent modern increase of red tides and the possible correlation with temperature and/or salinity. First, varved marine sediment cores were used to show that there is a good correlation between annual cyst concentrations and PSP plankton numbers. Subsequently, three geological case histories were studied in Atlantic Canada: Bedford Basin, Nova Scotia, Emerald and La Have basins, on the Scotian Shelf. Here cysts of Alexandrium tamarense show peak abundances either during the 6 Ka Holocene thermal maximum (e.g. in Bedford Basin) or at about 7,500 yrs B.P. Two case histories are now being studied at sites on the West coast: in Saanich Inlet and Santa Barbara Basin, respectively. Here records of Alexandrium, G. polyedra and Gymnodinium catenatum also suggest that larger and more frequent blooms of PSP species occurred in the 1 degree C warmer climate interval 6,000 to 7,000 yrs B.P. The continuous Holocene record of annual (varved) sediment deposits at ODP Site 1034 also allows analysis of seasonal changes in red tide production. The seasonal records show that there were much larger blooms of non-toxic red tide species, e.g. Protoceratium reticulatum, and G. spinifera when summers were warmer ca. 10,000 years ago, although the annual sea surface temperature at this time was lower than now.

Samuel Piriou¹, Daniel Michoux ² and Rene Braun ²

¹Université Claude Bernard

²TOTALFINA, Route de Versailles 78470, Rémy-les-Chevreuse, France

The organic content of Early Cretaceous sediments deposited in the Austral Basin of Tierra del Fuego (Argentina) was studied and correlated with the various depositional settings (flood plain, bay/lagoon, shoreface, offshore). Samples were submitted to standard palynological processing. The unoxidized residue was then split in two fractions: 10 to 200µm and above 200µm. One slide was mounted for each fraction. These are also referred to as "fine" and "coarse" fractions in the discussion below. The organic residue components are subdivided into three main categories, namely phytoclasts, palynomorphs and Amorphous Organic Matter (AOM). Phytoclasts comprise the following elements: inertinite, vitrinite, structured wood debris, cuticles and epidermal tissue. Palynomorphs are both terrestrial (pollen and spores), and marine, (dinocysts, acritarchs, foraminiferal linings). The characteristics of the different environments can be summarized as follows:

Flood plain: The coarse fraction is dominated by vitrinite and inertinite. The fine fraction shows very high frequencies of terrestrial palynomorphs (up to 50%).

Upper shoreface: the coarse fraction is winnowed away. The fine fraction is dominated by vitrinite and inertinite.

Middle shoreface: the coarse fraction is dominated by highly resilient particles (vitrinite and inertinite), while the fine fraction is characterized by abundant structured debris.

Lower shoreface: structured debris increases in the coarse fraction, while inertinite and vitrinite are prominent in the fine fraction.

The shoreface-offshore transition is marked by the dominance of structured elements (wood and thick, dense, resilient cuticles) in the coarse fraction. The fine fraction shows equal proportions of wood debris, tracheids and low buoyancy elements (small size cuticles, pollen and spores). Lower offshore facies are characterized by the dominance of thin cuticles in the coarse fraction. Spores, pollen and cuticles dominate the fine fraction. Of note is the prominence of blade shape elements. AOM is present, albeit in variable proportions, in all depositional environments. It is most prominent in condensed, glauconitic intervals. However there is a great variability in this so called "amorphous" material. Up to 10 AOM types were distinguished, based on size, shape and color. As an example, shoreface facies are characterized by large (ca 150µm) brown to dark gray flakes, whereas bay facies show grayish-pink small fragments (ca 10µm) or large sheet-like elements, the latter possibly derived from bacterial degradation of cuticle fragments.

Mirta E. Quattrocchio ¹ and William A.S. Sargeant ²

¹Departamento de Geologia, Universidad Nacionale del Sur, 8000 Bahia Blanca, Argentina

²Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2

The dinoflagellate assemblages from the Punta Pratt locality, on the western side of the Brunswick Penninsula , Chile, are described. The oldest Tertiary rock unit recognized within this area is the Chorrillo Chico Formation. It consists of a hard, shaley, glauconitic siltstone with thin beds of limestone and limestone concretions. The following stratigraphically important species occur in this formation: Deflandrea cygniformis, D. dilwynensis, D. fuegensis, Hafniasphaera cryptovesiculata, Hystrichosphara cornuta, Paleocystodinium golzowensis, Palaeperidinium pyrophorum, Pyxidinopsis waipawaensis, Spinidinium densispinatum, S. macmurdoensis, Thalssiphora pelagica, Turbiosphaera filosa, and others. The stratigraphic distribution of the dinoflagellate species in the profile is presented. A Paleocene age (Mid to Late ?) is proposed for the studied section. A comparison with other basins, especially from the southern hemisphere, is attempted.

Mirta Quattrocchio¹and Wolfgang Volkheimer²

¹Departamento de Geologia, Universidad Nacional del Sur, 8000 Bahia Blanca, Argentina

²CONCIT, Instituto Argentino de Nivologia, Glaciologia y Ciencias Ambientales, 5500 Mendoza, Argentina

Two major paleophytogeoprovinces can be recognized in the Danian of Argentina, based on the palynological record. Data exist at the generic, specific, and paleocommunity levels. The presence of Verrustephanoporites simplex Leid. (Ulmaceae) in the north is associated mostly with tropical and subtropical families, and Nothofagidites pollen in the south is mostly associated with temperate families. In the central-northwest of Argentina a subprovince with "triprojectate" pollen (Michedlishvilia) could be distinguished. Warm and humid climatic conditions are indicated for the Ulmaceae Phytogeoprovince, and more temperate conditions for the Phytogeoprovince of Nothofagidites. A brief consideration of the Mesozoic-Cenozoic paleogeographic and geodynamic evolution of southern South America is presented.

THE SIGNIFICANCE OF A TURONIAN SPORE AND POLLEN FLORA FROM THE MATANUSKA FORMATION, TALKEETNA MOUNTAINS, ALASKA (POSTER)

Sabra L. Reid¹ and Anne D. Pasch ²

¹Alaska Museum of Natural History, Eagle River, Alaska USA 99577

²Department of Geology, University of Alaska, Anchorage, Alaska USA 99508

A diverse suite of over 80 species of a paleomicroflora was recovered from the marine mudstone matrix surrounding a Turonian hadrosaur that was discovered in the Talkeetna Mountains in 1994. The dinosaur is one of the oldest hadrosaurs found on the North American continent. The unusual dinosaur occurrence was also associated with a suite of 90 million year old marine invertebrates, including two species of ammonites previously unknown in Alaska, and was deposited in an outer shelf or upper bathyal environment at a paleodepth of approximately 35 m. The fossil-bearing beds occur in the Matanuska Formation, in the southeast portion of the Talkeetna Mountains approximately 126 miles north of Anchorage, Alaska. This formation also contains remnants of a small Mesozoic volcanic island arc.

Most grains of this spore and pollen flora, especially the gymnosperm pollen, were moderately to strongly corroded. However, many spores of the pteridophyte species are generally robust and, in some cases, show slight to no signs of corrosion. Initial classification of these palynomorphs revealed relatively large abundances of 5 angiosperm species, 10 gymnosperm species, 69 pteridophyte species, but no sphenopsid species, one grain of a lycopsid species, and 1 grain of a bryophyte species. This spore and pollen flora suggests that Alaska’s oldest fossil dinosaur lived in a volcanic island arc terrestrial ecosystem containing a mixed forest with abundant ferns.

The Turonian-aged microflora containing extremely low numbers of lycopsid and bryophyte species is in contrast to the abundance and species diversity of the microfloras from several other sites within the Matanuska Formation. The microflora of Campanian age from Hicks Creek, and the microfloras from Mazuma Creek, Syncline Mountain and Slide Mountain, all of Campanian to Maastrichtian ages, contain large numbers of lycopod and bryophyte spores, although there is a limited number of species.

Fredrick J. Rich

Department of Geology and Geography, Georgia Southern University, Statesboro, Georgia USA 30460

The distinction between the Tertiary and the Quaternary of the Georgia Coastal Plain is notoriously difficult to define. The fact that the southeastern United States has remained in the tropics or subtropics for millions of years has lead to there being remarkable floristic stability. There is a resulting lack of significant, abundant , and easily identified palynological biostratigraphic markers. Furthermore, the uniformity of depositional systems that has prevailed, the lack of abundant, well-exposed outcrops and road cuts, and the intensity of weathering have resulted in most strata looking nearly the same regardless of geographic location or stratigraphic position. Huddlestun’s 1988 discussion of the Miocene through the Holocene of the Georgia Coastal Plain remains our most comprehensive treatment of the subject, but it lacks significant detail as to how one can reliably distinguish strata in the region.

Recent palynological investigations from areas as diverse as Grays Reef National Marine Sanctuary, the Boatright kaolin mine near Deepstep, Georgia, and a railroad yard near Waycross, Georgia, have lead to several conclusions that bear upon the question "Is it Tertiary or Quaternary?"

1. If the strata are of Late Tertiary marine origin (e.g., the Pliocene Raysor Formation) they may be abundantly fossiliferous, bearing many biostratigraphically useful molluscs. Exposures, though palyniferous, are very, very rare, however.

2. Late Tertiary samples can be expected to contain large numbers of extant pollen and spore genera. This is no surprise insofar as the dominance of living taxa over extinct forms was how the Late Tertiary was originally defined.

2. Extinct or extirpated genera usually include Pterocarya and Sciadopitys. Amounts will be as small as .5-1%, but they are consistent.

3. The onset of Late Tertiary-Early Quaternary glaciations resulted in the southward migration of the temperate flora, but it did not replace the indigenous flora. Curiously mixed communities that have no modern analog (i.e., no model) were common.

4. The southward migration of the temperate flora was not necessarily accompanied by spruce-fir forest. Looking for Picea as a sign of Quaternary cooling may not be as valuable as looking for increases in Alnus.

5. It appears that making the distinction between Miocene and Early Quaternary may be as difficult as distinguishing between Pliocene and Early Quaternary. In the Inner Coastal Plain the biostratigraphic distinction seems to be defined by the presence of marine dinoflagellates in the Miocene. These may be accompanied by attapulgite.

Continued efforts will certainly result in clarification of the lithostratigraphic and biostratigraphic details of the Georgia Coastal Plain. In spite of our best efforts, however it is largely terra incognita.

Eddie B. Robertson

Math and Sciences, Reinhardt College, Waleska, Georgia USA 30183

The study summarizes the dinoflagellates, pollen and spores, and fungal fruiting structures identified in samples from the aquifer test core VG-7, in Burke County, Georgia, and compares the results to an earlier study of cored material from the Savannah River Site in Aiken and Barnwell Counties, South Carolina. The concurrent ranges of the dinoflagellates Apectodinium homomorpha, Wetzeliella coleothrypta and W. articulata suggest an Early Eocene (probably Lutetian) age determination. The dinocyst assemblage used to date the coastal Georgia and South Carolina sediments is a local expression of the widely recognized Early Paleogene Wetzeliella Event. Within the Mackenzie Delta in northwest Canada, Staplin et al. recognize a Wetzeliella association including Apectodinium homomorpha and other species related to W. articulata which provides the most useful biostratigraphic zone in the Mackenzie Delta Paleogene section. In Paleocene to Early Eocene sediments form offshore eastern Canada, Williams and Brideaux report a similar palynoflora dated Early to Late Eocene based on the abundant occurrence of Apectodinium homomorpha along with W. coleothrypta and Rhombodinium glabra. In wells from the Grand Banks and the Scotian shelf, Williams and Bujak also report a related Areoligera senonensis Peak Zone characterized by the abundance of Wetzeliella homomorpha and Areoligera senonensis. They compare their dinocyst assemblage to the Early Eocene assemblages described by Morgenroth and Gocht from northwest Europe. In the Tertiary sediments of the Norwegian-Greenland Sea, Manum reports a similar diagnostic (Wetzeliella) Apectodinium assemblage in the Early Eocene sediments. The Georgia/South Carolina in situ assemblage indicates that the sediments represent shallow water (lagoonal) environments. Associated with the lagoonal environments are riparian sources of high terrigenous input. Fluvial input into the shallow lagoons carried sporomorphs that represent both subtropical coastal swamps and temperate riparian themophilic deciduous forests. The presence of similar terrigenous input is evident in the Mackenzie Delta, Scotian shelf, and Greenland occurrences.

FOSSIL POLLEN RECORDS AND THE ORIGIN OF MANGROVE COMMUNITIES

Valentí Rull

PDVSA Exploration & Production, Box 829, Caracas 1010-A, Venezuela.

Contrary to the current view that mangroves originated more or less synchronously around the world near the Late Cretaceous/Paleocene (~65 Ma), this report proposes that, in the Caribbean region, these communities did not establish in full until the early/middle Eocene (54 to ~40 Ma). According to the results presented, although few mangrove-related elements were already present in the Late Paleocene, the dominant and structurally-important taxa did not appear until the early Eocene. They were, however, too scarce to develop extensive mangrove ecosystems. The first record of well-developed Caribbean communities is in the middle Eocene. These results are an example of qualitative studies based only on presence/absence fossil data can lead to wrong conclusions. Similar studies are proposed for other tropical regions that host mangrove ecosystems.

Valentina L. Shalaboda

Institute of Geological Sciences, NAS of Belarus, Kuprevicha st, 7, Minsk, 220141, Republic of Belarus

A comparative analysis of nine pollen diagrams derived from seven sections of Muravian (Eemian) Interglacial deposits from several areas of Belarus was carried out. The studied deposits of the Niemen and Dnieper drainage basins are represented by owbow and oxbow/lacustrine genetic types (gyttja, peat, interbeded sand and sandy loams). Their thicknesses vary from 1.5m in the Bogatyrevichy 2 sample to 3.7m at Pyshky. In the northeastern and southern regions of Belarus the cores went through 1.5m of lacustrine deposits (marl, diatomite) at Vladyky and of 29.0 m at Shetena. Thin deposits (1.5m) investigated in Khmelevka consist of peat which accumulated in a shallow lake.

Pollen zones are identified as follows:

szi, Postglacial - Picea-NAP-Betula, or Pinus-Picea-NAP-Betula

mr1, end of the Interglacial - maximum Betula

mr2, maximum PInus

mr3, Pinus-Betula-Quercus, or Pinus-Betula-Carpinus

mr4, maximum Quercus-Pinus-Corylus

mr5, maxima of Corylus, Tilia, and Alnus

mr6, maximum Carpinus

mr7, maxima of PInus-Carpinus-Corylus or Pinus-Corylus-Quercus-Carpinus

mr8, beginning of the Interglacial - maximum Betula and NAP

pzs, the Preglacial - maximum NAP-Betula

The most distinct differences were revealed between the sites in the Niemen (western Belarus) and Dnieper (southeastern Belarus) drainage basins. These include strata from both the Postglacial and the Optimum phases of vegetation development. The prevalence of Pinus with decreasing Picea values is characteristic of the Postglacial pollen zone of the sections from the Niemen basin. Larix is present continiously up to the mr5 zone. In the southeast area of Belarus in sections from the Dnieper basin, the Postglacial pollen zone is characterized by domination of Picea with a high NAP percentage, while Larix appears for the first time only in phase mr8. Significant amounts of Quercus appear earlier in sections from the Niemen basin than elsewhere. A comparatively high content of Ulmus is peculiar in these sections as well. Pollen of Corylus and Carpinus appear first in the Dnieper drainage basin. The other diagrams reflect a gradual transition from the vegetation of the Niemen basin to the vegetation of the Dnieper basin.

The regional variations that are revealed enable us to elucidate the stages of vegetation development in Belarus. The most distinct differences can be seen when the sections Pyshky and Loev 2 are compared. The Postglacial spore-pollen spectra are characterictic of both sections. It is known that lakes of Muravian (Eemian) age were most numerous in Belarus during phases mr5 (the maximum of Tilia) and mr6 (the maximum of Carpinus). Shallow lakes existed even within small depressions in uplands at Khmelevka. Worthy of note is a rather significant percentage ofPicea in zones mr6- mr7 in the western (Bogatyrevichy) and northwestern (Vladyky) sections, and tts stable though not high values in the southern sections (Shetena). Very small amounts occur in the southeast section at Loev. Additionally, within zone szi in the latter section, Picea achieves its maximum abundnace. The transition from the Postglacial to the Interglacial was gradual. In the section known as Loev 2, pollen of the arboreal species of the Interglacial appears for the first time in the background, with a rather high percentage of the NAP (Artemisia, Chenopodiaceae, Poaceae being the dominants among the latter). Rare grains of Quercetum mixtum appear first in the southeastern sections, though a noticeable percentage of this pollen is recorded in older pollen zones in the diagrams derived from the western sections. A significant difference in the Tilia contents is observed between the studied sections. Its maximum amounts are in the spore-pollen spectra of the western sections, while the amounts of Corylus decrease from the west to the southeast.

Valentina L. Shalaboda

Institute of Geological Sciences, NAS of Belarus, Kuprevicha st, 7, Minsk, 220141, Republic of Belarus

During a palynological study of five sections from the western and eastern part of the Minsk Upland in Belarus we discovered and described the pollen of two species of the genus Armeria Willd. The investigated deposits formed in basins of various types. Basal interglacial deposits from the Matveev Rov ravine and Borehole 9 (Baranovichi) are composed of marl and diatomite that is indicative of deep-water basinal conditions. Boreholes 156 and 195 (near the village of Sokoly) produced stratified sandy loam with intermittent but intact pollen and spore spectra suggesting breaks in sedimentation that developed apparently within a low flloodplain. Borehole 7 (near the village of Shalashi) included deposits of littoral origin, an interpretation that is based on the presence of abundant stalks of higher aquatic plants. this interpretation is supported by the presence of interstratified gyttja and sandy loam that accumulated in association with water level changes in this part of the basin (produced, perhaps, in an oxbow lake).

All the investigated deposits occur at almost equal absolute heights, are underlain and overlain by sand, with moraine found in some of them near the bottom (Borehole 156 and 195), and at the bottom and top (Borehole 7). The pollen and spore spectra that we obtained illustrate the evolution of the vegetation of the period, namely the Alexandrian Interglacial (Middle Pleistocene) before the beginning of the Dnieper Glaciation. The summary palynological diagram may be subdivided into several pollen zones that correspond to certain stages of the vegetation evolution (from al2 up to dns). Individual pollen grains of thrift (Armeria) were found in pollen spectra of zones al5 and dns in all the investigated sections. The fossil pollen was identified specifically, using data obtained from recent pollen observed with a scanning electron microscope (SEM). The following conclusions were made:

1. The discovery of pollen of entomophilous Armeria in the deposits suggests

that it grew in the studied region or nearby. If the occurrences are of regular character, zonal distribution of a species may be suggested.

2. At the beginning of the Dnieper Glaciation at least two species of thrift grew in the territory of Belarus. They were identified as Armeria vulgaris Willd. and Armeria cf. scabra Pall. ex Schult. These species showed a zonal distribution

which is evident from their presence in sandy and sandy - loam deposits of the end of the Alexandrian Interglacial - beginning of the Dnieper Glaciation (al5 , dns) both to the west and to the east of the Minsk Upland.

3. The fossil pollen of Armeria may be determined in SEM even from fragments of pollen grains when atlases for species determination by SEM are available, or when recent pollen is studied simultaneously, because basic species distinctions are shown in elements of the tectum structure.

4. At the beginning of the Dnieper Glaciation, arctic species appeared in the middle lattitudes and form joint areas with local species.

5. The recognized zone of thrift with pollen of two species of thrift found in pollen and spore spectra allows the correlation of several sequences and helps in determining the Alexandrian age of deposits with even fragmentary palynological spectra.

Paul K. Strother¹ and Gordon Wood ²

¹Weston Observatory of Boston College, Weston, Massachusetts USA 02493

¹ 23222 Willow Pond Place, Katy, Texas USA 77494

Cryptospores of probable embryophyte affinity have been recovered from Middle Cambrian rocks in both eastern and western North America. The microfossils are preserved in tetrad and dyad configurations, in addition to cell clusters and solitary cells.  Many are surrounded by resistant envelopes. The discovery by Edwards, Wellman and others of cryptospore dyads in early Devonian rhyniophytoid sporangia, provides an unambiguous association between dispersed cryptospore dyads and embryophytes.  Since the prior first occurrence of cryptospores was Llanvirn (early Middle Ordovician) in age, there is now a considerable temporal gap between the first occurrence of cryptospores and the first macrophytes in the Silurian.  Some previously problematic palynomorphs of Late Cambrian to Early Ordovician age can now be properly interpreted as cryptospores, especially Attritasporites and Virgatasporites which are found in the Lower Ordovician of North Africa, the Prague Basin, and in Sardinia.  It is now possible to construct a fossil record of spore-like microfossils of probable embryophytic affinity throughout most of the lower Paleozoic.  Fossil evidence supports the acquisition of resistant-walled spores borne in tetrads and dyads as a primitive embryophytic character that originated by the Middle Cambrian, predating the evolution of vascular tissue (tracheids) by 100 Myr.  This is consistent with botanical arguments supporting hepatics as the basal embryophyte group.  Plants of bryophyte grade could have occupied a range of subaerial, terrestrial habitats from Middle Cambrian through Silurian time, forming an evolving eoembryophytic flora. A Cambrian origin for land plants opens up a plethora of potential speculation regarding possible links between the invertebrate Cambrian explosion in the marine realm and the origin of terrestrial photosynthetic ecosystems.  But two possible evolutionary scenarios seem worth pursuing: 1) the trophic links between detrital and dissolved carbon runoff and marginal marine ecology as an agent for evolutionary change, and, 2) the possibility that common extrinsic thresholds (such as pO₂levels) were breached to produce two different but extremely far-reaching results.

Sarah H. Tiffin¹, F.M.G. McCarthy¹, and Steve Blasco²

¹Department of Earth Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1

²Geological Survey of Canada

Cores taken from within Georgian Bay near Manitoulin Island contain a palynological record extending back to the end of the latest Pleistocene. This record correlates well with standard records compiled from elsewhere in Central Ontario. Previously established dates for pollen zones provide a temporal proxy that is correlated with sedimentological data to provide evidence for and date periods of high and low water levels in the Georgian Bay basin. Changing lake levels in the basin were mainly the result of isostatic rebound and changing outlet levels for the upper Great Lakes, although climate change may have also contributed to past fluctuations.

Five cores taken along a transect off the southeast shore of Manitoulin Island were analyzed and appear to record a series of low level stages in the Georgian Bay basin during the Mattawa phase. When comparing the palynostratigraphy and lithostratigraphy of the cores along the transect, a distinct pattern of sedimentation emerges. The oldest sediments, deposited from 12, 000 to 9,000 yr BP drape the entire basin, while sedimentary units deposited after this time are characterized by sediments eroded from the shoreline and exposed bathymetric highs, due to the high energy conditions in the basin during the Nipissing Transgression, a long period of steadily rising water levels. Following a long hiatus in sedimentation in the basin, infilling resumed in bathymetric lows about 130 yr BP when sediments were again available for erosion into the basin as a result of human land disturbance. Evidence for active modern sediment transport is found in a series of underwater dunes composed of recent sediments found off Tobermory. The result of this pattern of sedimentation is that sediments of greatly differing ages are exposed on the surface of the lake bottom in Georgian Bay.

Anneli Uutela¹ and William A.S.²

¹Geological Museum, P.O. Box 11 (Snellmaninkatu 3), Fin - 00014, Helsinki University, Helsinki, Finland

²Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2

A restudy of the Ordovician (Arenig-Llanvirn) acritarch genera Tranvikium polygonale Tynni, 1982 and Ampullula suetica Righi, 1991, indicates that they represent extremes in a single morphological plexus. This ranges from forms with a polar "excystment" aperture (closed by an operculum or two opercular pieces) and a smaller opening (plugged or open) at the opposite pole, to forms lacking a polar aperture but having, at the opposite pole, a tube open distally and plugged or open basally. New morphological terms for these structures are proposed. The genera and species are treated as synonyms and an emended diagnosis is given for Tranvikium polygonale. The possible purposes of the structures exhibited and the likely affinity of T. polygonale to various groups of algae are discussed.

V. Wahnert and B.A.R. Mohr

Museum fur Naturkunde, Inst. fur Palaontologie, Berlin, Germany

During ODP (Ocean Drilling Program) Legs 120 and 183 to the Kerguelen Plateau, early Albian to late Albian/early Cenomanian material was cored. These sediments overlay the basaltic basement and are of terrestrial origin. The kerogen consists mostly of large plant debris and contains, in addition to cuticles showing excellent preservation, palynomorphs and pieces of wood, the latter of which are in part highly charcoalified. These are considered to be recycled from strata which were in contact with the lava flows. The basement age for Leg 120, Site 750 has been radiometrically determined as ca. 110-120 Ma. This age is in accordance with data gathered from the sporomorph flora in Cores 14 through 12, which indicate an early Albian age (late Microcachryidites to early Hoegisporis - miospore superzone). Sediments recovered at Site 1138, Cores 73 and 72, which also directly overlay basement, are slightly younger according to palynodata, and are of late Albian to early Cenomanian age.

Site 1138 sediments contain a mesoflora in addition to the diverse palynofloras. This consists mostly of fern and conifer remains, such as abundant sporangia of Gleicheniaceae, conifer wood, and fragments of resin. The palynofloras from both sites contain mostly fern spores and conifer pollen. During the early Albian, fern spore diversity reached over 40 taxa; it was even slightly higher in the late Albian/early Cenomanian. The conifer pollen include various species of Cheirolepidiaceae, podocarps including Podocarpus , Microcachrys, Dacrydium, and Trisaccocladus, as well as Araucariaceae (Araucaria and Callialasporites). Pteridosperms, cycads, and angiosperms are also present. Angiosperm pollen are very rare and consist mostly of monocolpate pollen types. During the late Albian the Balmeiopsis - type pollen, which might have derived from araucarians, seem to have increased in comparison to older floras. Meso- and palynofloras reflect very well the paleovegetation during the Albian/early Cenomanian in the southernmost Gondwana region. The paleovegetation was characterized by conifer woods with diverse ferns, but rare cycads and angiosperms in the understory. This vegetation is characteristic for the southernmost paleobiogeographic province, and indicates that the Kerguelen Plateau during the Albian was located in very high latitudes.

POSSIBLE CHROOCOCCACEAE COLONIES FROM THE LOWER ORDOVICIAN COOLIBAH FORMATION, GEORGINIA BASIN, QUEENSLAND, AUSTRALIA (POSTER)

Reed Wicander¹ Clinton B. Foster² and Geoffrey Playford³

¹Department of Geology, Central Michigan University, Mt. Pleasant, Michigan USA 48859

²Australian Geological Survey Organisation, Canberra 2600, Australia

³Department of Earth Sciences, The University of Queensland, Brisbane 4072, Australia

In 1988, Playford and Wicander reported a well-preserved and moderately diverse acritarch assemblage from seven samples of the lower Ordovician (Arenig) Coolibah Formation intersected in Mount Whelan 2 borehole, Georgina Basin, Queensland, Australia. In addition to the acritarchs, the enigmatic palynomorph Gloeocapsomorpha prisca Zalessky, 1917 emend. Foster, Reed, and Wicander 1989 was also reported and recorded as the most abundant palynomorph. Reexamination of this non-acritarch palynomorph indicates it is not identifiable with G. prisca.

The supposedly G. prisca-like algal masses were described as consisting of a tightly packed mass of individual cells, each of which is circular or oblong to pillow-shaped in outline, and originally inflated. The cells are consistent in size within the mass and range in maximum diameter from 8 to 21µm. The cells are also closely packed vertically and horizontally with distinct contacts between them. While some of these masses superfically resemble G. prisca, their structure and arrangement precludes assignment to G. prisca, thus necessitating renaming and reassignment of them to another algal group.

Because new taxonomic names cannot be validated in an abstract, we note that these palynomorph masses most closely resemble the extant cyanobacteria Merismopedia, a member of the family Chroococcaceae and order Chroococcales. Merismopedia forms tabular colonies resulting from cell division along only two planes. Modern Merismopedia are abundant in fresh water and also occur in salt marshes, coastal, and brackish waters. This setting is consistent with the subtidal and/or intertidal marine paleoenvironment suggested for the Coolibah Formation. Lithologically, the Coolibah Formation is a varied and somewhat repetitive sequence of dense, fine-grained, grey to white limestones, dolostones, and grey calcareous siltstones. Within the carbonates, algal nodular beds are common as are occasional cherty lenses.

Based on the morphologic similarity of the palynomorph masses to extant Merismopedia, we believe these Ordovician forms may represent fossil representatives of the cyanobacteria family Chroococcaceae that either were transported into the intertidal-subtidal marine Coolibah environment or were flourishing in that environment.