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William A. Gregory and George F. Hart
Fifty conventional core samples from the Ragley Lumber #D1 well located in Allen Parish, Louisiana (Sec 29, T5S, R7W) were analysed for terrigenous palynomorphs. The sediment was deposited during the Sabinian in a marine environment as evidenced by the presence of in situ dinocysts and acritarchs in every sample.
One hundred twenty-nine terrigenous taxa are recognized as compared with marine palynomorph diversity of 46 taxa. Single sample diversity among the terrigenous palynomorph component ranged from 23 to 65 taxa, while single sample marine palynomorph diversity ranged from 7 to 25 taxa. High terrigenous diversity intervals possibly indicate sourcing from multiple onshore environments or a single onshore environment with a very diverse flora.
Because the terrigenous component is reworked from the onshore environments to the offshore ones, intervals of terrigenous abundance possibly indicate deltaic progradation associated with changes in sediment supply or sea-level. Confirmation of this interpretation awaits regional studies.
The subdivision of the section into palynofacies based on the terrigenous portion of the palynoflora shows general correspondence with the palynofacies of Gregory (1991) based on the total palynoflora. In general, mean percentages of palynomorphs used in the process of discrimination were lowered by the exclusion of the marine portion of the palynoflora.
The Sabinian-Claibornian boundary is not present in the cored interval, based on consistant occurrences of Thomsonipollis magnifica (Thomson & Pflug 1953) Krutzch 1960 at the top of the core. The absence of diagnostic middle and late Paleocene indicator pollen, such as Momipites dialatus (Fairchild) Stover et al. 1966 and Holkopollenites chemardensis (Fairchild) Stover et al. 1966 along with other characteristic palynomorphs, suggests that the entire Sabinian is not present in the core as was previously believed based on lithostratigraphic studies (Lowery, 1987).
Due to the lack of regionally significant taxa with restricted temporal distributions, a biozonation for the Ragley Lumber #D1 well is proposed based on the constrained palynomorphs from the principle components and discriminant function analyses.
William A. Gregory and George F. Hart
Fifty conventional core samples from the Ragley Lumber # 1 well located in Allen Parish Louisiana (Sec 29, T5S, R7W) were analyzed for palynomorphs. Dinoflagellate cysts, not considered to be recycled, were present in all samples along with abundant to very abundant pollen, spores and fungal spores. Dinoflagellate cyst abundances varied considerably from sparse (< 20 cysts per sample) to abundant (> 100 cysts per sample). Preservation also displayed considerable range, even within the same sample.
Biostratigraphically useful taxa include: Adnatosphaeridium multispinosum, Apectodinium homomorphum, Areosphaeridium dictyoplokus, Deflandrea phosphoritica, Spinidinium sagittula, Lingulodinium machaerophorum, Muratodinium fimbratum, Palaeocystodinium golzowense, and Hafniasphaera septata.
Other taxa described include: Achomosphaera alcicornu, Cleistosphaeridium diversispinosum, Cordosphaeridium inodes, Diphyes colligerum, Operculodinium centrocarpum, Polysphaeridium subtile, Trichodinium hirsuitum, and Senegalinium sp. 1. In addition to the indigenous flora, a recycled flora was also encountered. These specimens were assignable to the following genera: Muderongia, Dinogymnium and Odontochitina.
Based on abundances of Spiniferites and Cleistosphaeridium types and general scarcity of peridiniacean dinoflagellate cysts and Impagidinium species an outer neritic water depth is postulated. Benthic foraminiferal data from a section of the core generally support this interpretation.
Scott W. Mathison and Gail L. Chmura
In this study we examine the nature of microforaminifera test linings found in palynological preparations and demonstrate the potential of these palynomorphs for paleoenvironmental interpretation. Sediment samples from four marsh salinity zones of the Barataria Basin, Mississippi Delta, were processed by conventional palynological techniques which included HCl and acetolysis treatments. Taxonomic identification was not attempted, but it is assumed that Rotalidae forams, Miliammina fusca and Ammonia beccari, are important constituents of the test lining assemblages. Multi-chambered forms were classed by morphotype, size, number of chambers, spacing of chambers, and condition. The absence of a relationship between size and chamber number within each morphotype implies the presence of multiple species populations. There is also no relationship between foram concentration and salinity. Using stepwise discriminant analysis, six classes were selected which enable successful discrimination among the four salinity zones.
Stephen A. Hall
The Late Cenozoic lacustrine and fine-grained sediments from the south-central United States should contain abundant, well-preserved pollen assemblages; unfortunately, many are entirely devoid of pollen, while others contain only corroded pollen in low concentrations. The absence of pollen in the southern Great Plains is widespread, encompassing many lacustrine and alluvial deposits. This absence or poor preservation of pollen and other organic matter within these materials is probably the result of post-depositional biotic or chemical oxidation, perhaps related to drying out of the deposits and subsequent movement of meteoric or ground water through the sediments.
Among southern Plains localities barren of pollen are the type sections of the Clarendonian, Hemphillian, and Blancan North American Land Mammal ages in Texas. Other localities barren of pollen or containing low concentrations of poorly preserved grains include the Laverne (Miocene), Camp Rice (early Pleistocene), and Tule (early-middle Pleistocene) formations, sediments below the Pearlette O ("Lava Creek B") and Bishop ashes (middle Pleistocene), the Slaton (Illinoian), Easley Ranch (Sangamon), Quiteque, Jones, Howard Ranch (Wisconsinan), Clovis, Lubbock Lake, and Plainview sites (late Wisconsin-Holocene), and several early Holocene lacustrine and alluvial localities.
Only a few localities in the region have provided reliable pollen records. The Rita Blanca beds in the Texas Panhandle have yielded the only Pliocene pollen record in the region; it indicates a cool-climate sagebrush grassland vegetation. The only pre-Illinoian Pleistocene pollen record is Hansen Bluff, south-central Colorado, which shows local shifts from sagebrush grassland to forest vegetation. Illinoian-age pollen assemblages from northwestern Oklahoma and southwestern Kansas indicate a sagebrush grassland with significant percentages of pine and spruce, possibly signaling the presence of pine and spruce populations in the central Plains. Well-preserved Wisconsin-age pollen assemblages also document a full-glacial sagebrush grassland on the southern High Plains.
Owen K. Davis
Nearly 1,400 samples from over 50 sources have been assembled and analyzed to characterize the contemporary pollen rain of the arid western U.S.A. Of the nearly 300 pollen types recorded, Pinus, Quercus, and Cupressaceae are the most common arboreal types; Chenopodiaceae - Amaranthus, Gramineae, Artemisia, Ambrosia, and "Other Compositae" are the most frequent non-arboreal pollen types. Forest vegetation is represented by 661 samples, steppe by 450 samples, and desert by 116 samples. Ambrosia, Cactaceae, Cruciferae, Leguminosae, Larrea, Malvaceae, Nyctaginaceae, and Prosopis achieve maximum percentages in hot - dry climate (>20°C mean annual temperature and <250 mm mean annual precipitation); Artemisia, Juniperus, Sarcobatus, Caryophyllaceae, Liguliflorae, Other Compositae, and Polygonaceae have minor peaks in cold dry climate (<15°C and <250 mm); Arceuthobium, Abies, Picea, Pinus, Pseudotsuga, Sequoiadendron, Tsuga heterophylla, and T. mertensiana reach maxima in cool moist climate (10 - 15°C, 500 - 2000 mm); and Cyperaceae, Umbelliferae, and Salix reach maxima in cold wet climate (<5°C and >2000 mm). The frequency distribution of dissimilarity values among vegetation types is similar to that of other surface sample studies, with squared-chord-distances <0.15, five times more likely to be same-type comparisons than different-type. Holocene temperature and precipitation curves for three western U.S.A. sites, based on the closest analogs in the contemporary surface samples, exhibit the "early Holocene Xerothermic" of the Pacific Northwest and early Holocene moistness of the Southwest.
Hiroshi Kurita and David J. McIntyre
Shallow marine deposits of the Paleocene Turtle Mountain Formation on the northeastern flank of the Williston Basin, southwestern Manitoba, yielded dinoflagellate assemblages which include Senegalinium microgranulatum, S. obscurum, Senegalinium sp., Spinidinium densispinatum, S.? pilatum, Cerodinium speciosum, Isabelidinium viborgense and Phelodinium magnificum. The assemblages indicate that the Turtle Mountain Formation is Early to early Late Paleocene in age. Low species diversity and high dominance of a few species are characteristics of the assemblages and suggest a nearshore depositional environment for the formation. Additional investigation of dinoflagellates of the Cannonball Formation in southcentral North Dakota confirms an early Late Paleocene age which permits correlation of the Cannonball Formation with the upper part of the Turtle Mountain Formation. Distinct similarities are present in dinoflagellate assemblages of Paleocene marine deposits within the Williston Basin. The assemblages also have marked similarities with Paleocene assemblages of the eastern Gulf Coastal Plain, U.S.A., which suggests extension of the Gulf sea into the Williston Basin during the Paleocene.
Mary E. Dettmann, David M. Jarzen, and Susan A. Jarzen
Palynology has proven an effective method in providing supportive and new information on the visitation/foraging habits of the mahogany glider (Petaurus gracilis) in coastal northern Queensland, Australia. Pollen constitutes at least 30% by volume of the maceral contents in six of the eight fecal and intestinal samples examined. Pollen counts indicate that Myrtaceae taxa and Xanthorrhoea are the most frequently visited flowers, but significant occurrences of Banksia pollen suggest that it may also have been foraged. Incidental occurrences of Acacia, Grevillea/Hakea, Asteraceae, Casuarina, Deplanchea, and Ilex confirm the presence of these taxa within the glider's habitat.
John P. Kokinos and Donald M. Anderson
The previously undescribed morphological development of resting cysts of the living marine dinoflagellate Lingulodinium ("Gonyaulax") polyedrum has been observed in laboratory cultures. Referred to as L. machaerophorum in cyst-based taxonomy, this species has a fossil record extending back at least to the Early Eocene. In our cultures, planozygotes preparing to encyst showed a distinctive interstice in the peripheral cytoplasm and often displayed a characteristic swimming behavior. The transition from motile planozygote to morphologically mature hypnozygote (resting cyst) took approximately 10-20 minutes. Encystment began with several events occurring simultaneously: (1) the cell stopped swimming and came to rest at the bottom of the observation chamber, (2) flagella were expelled from their respective thecal grooves, (3) localized swelling of a membrane external to the theca formed bubble-like protrusions on the surface of the cell, (4) the theca began to dissociate along one or more plate sutures, and (5) a single layer of globules appeared in the interstice between the theca and cytoplasm. External protrusions then enlarged and merged to liberate a continuous membrane which surrounded the entire cell. Subsequent expansion of this membrane gave the encysting cell the appearance of an inflating balloon. In most cases, the outer membrane remained partially attached to the theca so that expansion caused thecal sections to pull away from the underlying globules and cytoplasm. As the outer membrane enlarged, globules on the surface of the cytoplasmic mass grew radially outward (i.e., centrifugally) beneath the dissociating theca to form processes. Morphological development of the resting cyst ended when the expanding membrane ruptured. The maximum lateral dimension attained by this membrane was about twice the diameter of the internal body of the cyst. In these cases, cysts developed the distinctive processes characteristic of Lingulodinium. Premature rupture of the balloon-like membrane, however, resulted in processes showing considerable variation in size and morphology. Based on the variability of process morphology observed in laboratory cultures of L. polyedrum, three morphotypes currently designated as separate species of the genus Lingulodinium are here synonymized with L. machaerophorum.
Susanne Feist-Burkhardt
The dinoflagellate cyst genus Willeidinium gen. nov., from the Middle Jurassic of France, shows an unusual, fundamentally gonyaulacacean paratabulation pattern with a reduced number of epicystal paraplates. The most important features are the presence of only five precingular and three apical paraplates, and one of two anterior intercalary homologues reaching the apex. The fifth precingular and the third apical paraplates are extremely large. This is interpreted as a result of fusion of adjacent paraplates (5'' + 6'' and 3' + 4') in a gonyaulacacean paratabulation pattern with A/ai-arrangement. The obvious relationship of Willeidinium with other Middle Jurassic leptodinioidean dinoflagellate cysts required the emendation of the families Gonyaulacaceae and Ceratocoryaceae. The application of the plate labeling systems of Kofoid and Taylor-Evitt is discussed. The type species, W. baiocassinum sp. nov., seems to be a good stratigraphic marker for the latest Bajocian to early Bathonian of Europe.
Svein B. Manum and Graham L. Williams
The unique archeopyle in the dinoflagellate cyst (dinocyst) genus Caligodinium Drugg has previously been regarded as apical gonyaulacalean with the operculum consisting of three partially or completely separated pieces, despite there being a problem with determination of the paraplate relationships. A more logical interpretation would be to regard the opercular pieces as representing the three fundital plates in a peridinialean tabulation, making the archeopyle hypocystal. The apparent stratigraphic range of the Caligodinium type of archeopyle is Albian to Early Miocene, although there is some uncertainty over the archeopyle morphology in the Cretaceous forms.
Thomas Servais and Klaus H. Eiserhardt
The new term "galeate" acritarchs is proposed for Lower Paleozoic taxa characterized by a hemispherical vesicle outline and with a large polar excystment opening closed by an operculum. Included in the "galeate" acritarch plexus are such common genera as Caldariola Molyneux in Molyneux & Rushton 1988, Cymatiogalea Deunff 1961, Priscogalea Deunff 1961, and Stelliferidium Deunff et al. 1974. An historical overview, a revision of the taxonomic concept, and proposals for a classification scheme at the generic level are presented.
The following "galeate" taxa are described from the late Tremadoc to early Arenig subsurface of RÄgen (NE-Germany): Caldariola glabra (Martin 1973) Molyneux in Molyneux & Rushton 1988, Caldariola sp. cf. C. glabra, Cymatiogalea deunffi JardinÚ et al. 1974, Cymatiogalea messaoudi JardinÚ et al. 1974, Cymatiogalea sp. cf. C. cristata (Downie 1958) Rauscher 1974, "Stelliferidium?" sp. 1, and "Stelliferidium?" sp. 2.
Susanne Feist-Burkhardt
The new phallocystean dinoflagellate cyst genus Weiachia is described from the Toarcian of Switzerland. In contrast to the genus Moesiodinium AntonesÙu 1974, the new genus is characterized by an intercalary archeopyle with an adnate operculum. The type species, W. fenestrata, has openings in the periphragm which correspond in geometry and topology to paraplates. For this kind of opening a new morphological term, "fenestrae" (sing. "fenestra"), is introduced. The generic value of the free versus adnate operculum, used by Below (1987) for differentiating phallocystean dinoflagellate cyst genera, is discussed. It is a stable character for the group and is therefore considered to be a better classificatory criterion than either wall structure or the degree of expression of paratabulation by ornamentation and protuberances; both are variable characters which have been used previously in generic differentiation. The differentiation of genera using a free versus adnate operculum seems to be useful in palynostratigraphy for the late Early to early Middle Jurassic.
Gordon D. Wood
The acritarch (organic-walled microphytoplankton) Bimerga bensonii gen. et sp. nov. has an elongate, bilaterally symmetrical vesicle with the poles bisected into two broad-based processes possessing homomorphic or heteromorphic terminations. This acritarch was first illustrated, and named in open nomenclature, from the subsurface of Ghana and is reported here from an outcrop sample of the Devonian Los Monos Formation and subsurface cuttings samples from Bolivia. The presence of Bimerga bensonii gen. et sp. nov. in both Africa and South America further supports the existence of an oceanic connection between these Malvinokaffric areas and indicates that palynomorphs may provide a key to intra- and intercontinental correlations for the Gondwanan Devonian.