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Ian D. Campbell and Celina Campbell
Experimental degradation of pollen by repeated wet-dry cycles in saline and desalinated sediments show differences in preservation between taxa and between salinity environments. In desalinated sediment, from which the salts were removed artificially, pollen is rapidly degraded, with a significant net loss of pollen after ten wet-dry cycles. Picea pollen, which remains identifiable even when heavily damaged, suffers greater breakage in desalinated sediments. Artemisia pollen is rapidly rendered unidentifiable by degradation of the sculptural elements in both saline and desalinated sediments. In comparison to desalinated sediments, saline sediments appear to contain less damaged pollen. Growing salt crystals may envelop the pollen grains and stabilize them against mechanical breakage otherwise incurred by flexing of the pollen wall during desiccation. Caution should be exercised when analyzing sediments subject to wet-dry cycles, and laboratory procedures modified if necessary to avoid desiccation of pollen during processing.
James B. Riding
The Lower-Middle Jurassic dinoflagellate cyst Fromea elongata Beju 1971 is superficially similar to the typically Lower Cretaceous species Wallodinium cylindricum (Habib 1970) Duxbury 1983. Fromea elongata is transferred to Phallocysta Dorhofer & Davies 1980 by virtue of its anterior intercalary periarcheopyle; the specific diagnosis is emended to include this periarcheopyle type. Andreedinium Below 1987 is considered to be a junior synonym of Phallocysta and A. arcticum Below 1987 is transferred to Phallocysta. The uppermost Jurassic-Cretaceous Wallodinium cylindricum is emended largely to note the loose mutual contact of the two cyst walls and the apical peri- and endoarcheopyles, the principal periarcheopyle suture of which appears to be indicative of a gonyaulacacean paratabulation. Wallodinium Loeblich & Loeblich 1968 is therefore emended to include epicavate forms and to note its apparent gonyaulacacean paratabulation. The range of Phallocysta elongata is uppermost Toarcian (Lower Jurassic) to lower Bajocian (Middle Jurassic); all known records are from Europe. Wallodinium cylindricum has been observed from the Kimmeridgian (Upper Jurassic) to the lowermost Cenomanian (Upper Cretaceous) of the North Atlantic, Europe and North Africa; it is most common and persistent in the Lower Cretaceous.
Stephen Ellin and Duncan McLean
The application of a commercially available, microwave digestion system to hydrofluoric acid digestion of rock samples for palynological analysis allows considerable savings of time, laboratory space, chemical costs and waste disposal costs. The system offers several advantages in terms of workplace safety and environmental hazard over existing rapid silicate digestion techniques.
Guus van de Geer, Linda E. Heusser, Jean Lynch-Stieglitz and Christopher D. Charles
Pollen and oxygen isotope analyses of sediments from deep-sea core SO36-7SL (42û18' S, 144û40' E; 1085-m water depth) provide a chronostratigraphically-controlled paleoenvironmental record of the last 75,000 years from southeastern Australia. During the early Holocene and later part of the preceding period of deglaciation (post-14,000 yr B.P.), the vegetation of coastal central western Tasmania consisted mainly of Phyllocladus-Eucalyptus mixed forest with a mesic understory, implying warm and humid climate. Grassy herbland communities with scattered Athrotaxis and Lagarostrobos were widespread during the last major phase of highland glaciation (~25,000-14,000 yr B.P.), and reflect much lower temperatures than at present. During much of the last glaciation (~63,000-25,000 yr B.P.), the vegetation was a mosaic of Eucalyptus woodland, shrubland, herbland and sedgeland communities that developed under generally cool and moist climate. Very high Asteraceae and low Eucalyptus, Phyllocladus and Dicksonia/Cyathea pollen and spore values indicate colder and probably drier environments ~70,000-63,000 yr B.P. The basal Eucalyptus-Dicksonia/Cyathea-Phyllocladus forest assemblage, deposited ~75,000-70,000 yr B.P., signifies a rapid transition from a moderately warm and moist interglacial-like climate to the colder conditions and open environments that characterized much of the last glacial period. The results of the past 50,000 years are broadly consistent with paleoenvironmental reconstructions inferred from radiocarbon dated lowland pollen sequences in western Tasmania and further afield.
Andrew McMinn and Sun Xuekun
Twenty-one species of dinoflagellate cysts are present in Recent sediments from around the Chatham Rise, Southern Oceam, east of New Zealand. Abundant species include Nematosphaeropsis lemniscata, Operculodinium centrocarpum and Spiniferites mirabilis. The distribution of many species show a close relationship to the major oceanographic frontal area, the Subtropical Convergence. One new genus, Dalella and two new species, Dalella chathamense and Pyxidinopsis reticulata, are described.
Ian D. Campbell and Gail L. Chmura
Thirty water samples from a cross-section of the Atchafalaya River taken at Morgan City, Louisiana in June 1991, have pollen concentrations on the order of 3500 grains/l. There are only rare grains attributable exclusively to long-distance transport from the northern United States, and the assemblage is dominated by species common in the local area. However, the condition of much of the pollen suggests that it is largely reworked.
Point-velocities obtained for each sample vary from 0.58 m/sec to 1.3 m/sec. There are only minor variations among pollen assemblages, with differences in velocity and position (i.e., water surface or deeper in the water column) having only minimal influence on the pollen distribution. It is likely the differences that do exist reflect unmixed waters of drainages which confluence immediately upstream of the sample site.
Compared to 1987 data from the Mississippi River, the June pollen spectra of the Atchafalaya are enriched in the locally abundant Taxodiaceae-Cupressaceae-Taxaceae. While the Mississippi has a June pollen concentration of about 2000 grains/l (approximately half of the Atchafalaya concentration), a higher proportion of the Mississippi pollen was damaged or degraded beyond identifiability. While this may suggest a greater contribution from reworked sediments, it may also be that the nature of the reworked sediment differs - the Atchafalaya may derive its pollen largely from eroded swamp and marsh sediments, in which the previously deposited pollen may be better preserved.
The Mississippi is estimated to supply some 10 to the power of 19 grains of pollen/year to the Gulf of Mexico; if the contribution of the Atchafalaya is of similar magnitude, then together they supply approximately 2000 grains/cm2/year to the Gulf. Information on the taphonomy of pollen grains in these rivers is not only important to analyses of pollen assemblages in sediments from the Gulf of Mexico, but can serve as models of fluvial transport and deposition in large river systems.
Xuekun Sun
Eocene dinoflagellate cysts from five exploration wells in the Liaohe Depression, northeast China, have been examined with particular emphasis regarding their morphology and taxonomy. Sixteen genera and 29 species of fossil dinoflagellates, including one new genus, Songiella, and two new species, Bohaidina tuberculata and Protoellipsodinium minutus, are described and illustrated. Songiella gen. nov. is proposed herein to include those dinoflagellate cysts which were originally described as Bipolaribucina huanghuaensis (Song et al., 1978). Four peculiar proximate cyst genera - Bohaidina, Parabohaidina, Conicoidium and Prominangularia - are discussed and emended on the basis of archeopyle morphology and overall shape. The emendation of Bohaidina suggests that it has a variable archeopyle (I, 3I or 3Ia) and that its shape varies from rhomboidal to approximately conical; this emendation makes Prominangularia a junior synonym of Bohaidina. Furthermore, Conicoidium is considered to be a junior synonym of Parabohaidina for similar reasons.
Sally P. Horn, Thomas R. Wallin and Lisa A. Northrop
A method is described for collecting soil pollen from mineral soil horizons, using a root corer and copper sampling tubes. The method is faster than traditional methods, which rely on the digging of a soil pit, and has the additional advantage of simultaneously providing large volume soil samples for companion analyses of macroscopic charcoal or other soil components.
Norman O. Frederiksen
This paper is based on study of angiosperm pollen from (1) 75 upper Paleocene samples from eight coreholes in the Lower Indus coal region of southern Pakistan, (2) two middle Paleocene and two upper Paleocene outcrop samples from the northern part of this coal region, and (3) eight middle Paleocene samples from the Surghar and Salt ranges of northern Pakistan. Forty-five formally named pollen species are illustrated as well as a number of informally named taxa. The known stratigraphic distributions are given particularly for the new species and for taxa that appear to have restricted stratigraphic ranges. The taxa studied include two new genera, Crassivestibulites and Rhombipollis, and 21 formally named new species: Triporopollenites ranikotensis, T. parviannulatus, T. cracentis, T. trilobus, Triatriopollenites rectus, Spinizonocolpites adamanteus, Longapertites psilatus, L. punctatus, L. discordis, L. dupliclavatus, Brevitricolpites vadosus, Myrtacidites secus, Warkallipollenites? medius, W.? solox, W.? exilis, Porocolpopollenites? duplex, Compositoipollenites dilatus, Crassivestibulites karii, Yeguapollis prolatus, Rhombipollis geniculatus, and Polycolporopollenites calvus.
Most taxa found in the upper Paleocene of southern Pakistan range throughout that subseries or are too rare to be useful as zonal indicators. However, three species do have range bases or tops that may be used for zoning or subzoning that interval.
According to data of pollen and other fossils, the upper part of the Bara Formation of southern Pakistan is probably lower Selandian, whereas the lowermost part of the formation is probably upper Danian.
More species of the brackish-water palm pollen genus Spinizonocolpites are now known from the middle and upper Paleocene of Indo-Pakistan than perhaps anywhere else in the world. Normapolles pollen is reported for the first time from the upper Paleocene of Indo-Pakistan. This pollen, the previously reported Normapolles pollen in the Upper Cretaceous of India, and the apparent lack of Normapolles pollen in the middle Paleocene of Pakistan, support the hypothesis of sporadic filtered migrations from Eurasia to the Indo-Pakistan island before the collision of the two continents in the middle Eocene.
Eva Bundgaard Koppelhus and Lars Henrik Nielsen
The Baga Formation includes up to approximately 400 m of paralic, lacustrine and alluvial deposits without marine macrofossils. Detailed palynological and sedimentological studies have been undertaken of all available cored boreholes and exposures of the formation. A total of 150 palynological samples were examined from partially overlapping sections amounting to a total of ca. 650 m. The palynomorphs recovered, some of which are stratigraphically important, comprise very diverse and well-preserved assemblages from which 130 species including 67 spore, 32 pollen and 31 microplankton species are identified. The assemblages are subdivided into the Chasmatosporites, Spheripollenites - Leptolepidites and Callialasporites - Perinopollenites miospore zones and the Mendicodinium reticulatum, Luehndea spinosa and Nannoceratopsis gracilis dinoflagellate cyst zones. Three of these, the Chasmatosporites, Callialasporites - Perinopollenites and Mendicodinium reticulatum zones, are newly proposed here. The BagÔ Formation spans the late Pliensbachian, Toarcian, Aalenian, Bajocian and Bathonian time intervals. This has an important implication for the recognition of the regional NW European mid-Jurassic unconformity on Bornholm, which is shown to occur within the formation and not at the base as previously thought. The unconformity divides the formation into a lower part with brackish-marine influence and an upper, non-marine part. The recognition of both the unconformity and late Pliensbachian-Toarcian marine incursions facilitate a close correlation with other Jurassic sections in the region. The study illustrates the value of combining palynology and sedimentology in interpreting the depositional history of non-marine and marginal marine successions.
Gordon D. Wood
Togachitina eamesi gen. et sp. nov. is described and illustrated from the Devonian Iquiri Formation of Bolivia. This new chitinozoan is flask-shaped (ancyrochitinid-like) and has a distinctive outer wall enclosing the entire vesicle. This is the second bilayered member of the Lagenochitinidae to exhibit an outer sleeve with pronounced separation of wall layers but the first with an ancyrochitinid vesicle shape. A new subfamily, the Togachitininae, is proposed for cylindro-conical chitinozoans with separated wall layers.
John G. Jones
Analysis of fossil pollen from the Maya site of Colha, Belize, revealed a complex history of human-caused forest and land modification. Evidence of forest clearing, irrigation canal and raised field construction, and prehistoric domesticated plant use are apparent in the fossil pollen assemblages. Radiocarbon dates attest to a widespread clearing and the early cultivation of manioc (Manihot esculentum) and probably maize (Zea mays) by 2500 BC, with later Maya populations growing cotton (Gossypium) and chilies (Capsicum). The use of pollen analysis at this tropical archaeological site provides a wealth of data unavailable through other means.
Fransisca E. Oboh and Lisa M. Reeves Morris
Palynomorph data from two localities in southwestern Alabama and southeastern Mississippi have been used to interpret the palynofloral succession of six of the seven lithostratigraphic units of the Vicksburg Group, to test the current sequence stratigraphic framework for the area, and to infer paleoclimatic conditions during the Early Oligocene. The samples group statistically by multivariate methods according to sporomorph types and relative frequencies, and two broad groups of high and low diversity assemblages have been identified. Quercoidites, Carya, Momipites, Siltaria sp. cf. S. scabriextima, Cupressacites hiatipites and Cupuliferoipollenites dominate the high diversity assemblage in the Bumpnose Limestone, Red Bluff Clay, Forest Hill Sand and Bucatunna Clay. These lithostratigraphic units have previously been interpreted as deposits of a highstand systems tract. The main difference between the Bucatunna sporomorph assemblage and that of the other units is the absence of the two taxodiaceous conifer pollen species resembling Sequoia. The Mint Spring Marl, which is considered the lower part of a transgressive systems tract, is slightly less diverse than the highstand deposits, but the assemblage is rich in the two Sequoia type pollen species. In southwestern Alabama, nonmarine palynomorphs outnumber marine palynomorphs in this unit, whereas the marine palynomorphs are the dominant constituents in southeastern Mississippi. This a reflection of transgression progressing from southeast to northwest that resulted in a thinner, older and more marginal Mint Spring facies in Alabama.
The low diversity assemblage is present in the transgressive Marianna Limestone and highstand Glendon Limestone. The Marianna Limestone has fewer sporomorphs than the underlying Mint Spring Marl, with Sequoia type pollen also accounting for >70% of counted sporomorphs, but the unit is much richer in marine palynomorphs than nonmarine palynomorphs. The Glendon Formation has the poorest recovery of nonmarine and marine palynomorphs among the sediments, and this poor recovery may be related to diagenetic processes.
The Early Oligocene paleoclimate was evidently warm temperate. Prominent in the Vicksburg assemblage are pollen elements related to Quercus, Taxodium, Sequoia, Cyrilla, and Castanea which suggest that the paleoclimate was cooler than the Gulf Coast Early and Middle Eocene subtropical conditions.