Distribution Of Palynomorphs Research Articles

Late Cretaceous/Early Paleocene Biostratigraphy of the Northern Portion of the Bornu Basin, Nigeria

Ditch cutting samples from Kasade-1 well were processed for microfauna, nannofossil and palynomorphs to throw more light on biostratigraphic events in the northern portion of the Bornu Basin, Nigeria. The lower section of the well within interval 990 - 1565 m yielded fairly abundant foraminifera species, while the upper section was barren. Palynomorph distribution follows the same pattern as observed for foraminifera except that few fresh-water algal species, Botryococcus braunii, were recovered from the upper section. The samples are devoid of nannofossil but contain few ostracod species, echinoid remains and fish tooth. Recognition of two planktonic foraminifera zones, Globotruncanella havanensis and Globotruncana aegyptiaca, enabled the delineation of the Campano-Maastrichtian and Maastrichtian boundary. The Cretaceous Tertiary boundary was inferred based on the top occurrence of palynomorph Dinogymnium euclaense. An abrupt truncation in the distribution of foraminifera species at a depth of about 990 m suggests unconformity, a widely reported event that followed the Santonian squeeze in the entire mega-Chad Basin.

Deposition pattern and sources of palynomorphs on the continental margin off Hokkaido Island, northwest Pacific

Abstract Hokkaido Island in northern Japan is located in a cool temperate to boreal climate zone influenced by summer monsoons and typhoons during summer–autumn, while its eastern area is influenced by the subarctic Oyashio Current. Palynomorph (pollen and spores) distribution was investigated in surface sediments from the shelf and slope (40–2300 m water depth) in the offshore area of Tokachi Plain, central-eastern Hokkaido Island. The objective of this study was to examine the source, transportation, and deposition of palynomorphs in marine environments. The majority of palynomorphs were transported from the Tokachi coastal plain by both strong local winds from the mountain areas during the spring–summer and the floods caused by heavy monsoon and typhoon rainfall. Approximately 10% of all palynomorphs were transported from both southwest and west areas by the wind. Palynomorph transportation by the Oyashio Current could not be discriminated because the same vegetation is present in Hokkaido and the islands in upper streams of the Oyashio Current. The total grain abundance was dependent on water depth. High concentrations were observed at depths of 700–1500 m, which is a region associated with high levels of fine silt and clay, suggesting that the transportation and deposition of palynomorphs are controlled by their grain sizes. This study supported a strong correlation between the distribution of sediments and the concentration of palynomorphs.

Middle-late Eocene dinoflagellate cysts from NE Ukraine (Borehole No. 230, Dnepr-Donets Depression): stratigraphic and palaeoenvironmental approach

Abstract Analysis of the stratigraphic and quantitative distribution of dinoflagellate cysts and other palynomorphs from a shallow marine Eocene section drilled from borehole No. 230 (NE Ukraine) resulted in an updated age-assessment of regional formations and a reconstruction of the major transgressive-regressive trends in the North Ukrainian palaeosedimentological province. Based on dinocyst age-diagnostic events, the Buchak Formation is attributed to the mid-upper Lutetian; the Kiev Formation is assigned to the Bartonian-?lowermost Priabonian; finally, the Obukhov Formation is dated Priabonian. The Buchak Formation accumulation reflects the first major transgressive episode in the North Ukrainian Province; the accumulation of the lower Kiev Formation corresponds to the maximum of regional marine transgression, while the palynological assemblages from the upper Kiev Formation indicate a protracted regression. The beginning of the Obukhov Formation accumulation corresponds to the last marine transgressive cycle.

Vegetation patterns, pollen deposition and distribution of non-pollen palynomorphs in an ice-wedge polygon near Kytalyk (NE Siberia), with some remarks on Arctic pollen morphology

In ice-wedge polygon mires, small-scaled microrelief of ridges enclosing small depressions results in a short-distance vegetation mosaic. The correct recognition of these landscape elements in palaeoecological studies of peat sections in order to reconstruct their patterns and dynamics requires insight in the short-distance relationship between vegetation and pollen deposition. This paper presents an analysis of pollen surface samples in a high-resolution (1 m) transect across an ice-wedge polygon near Kytalyk (NE Siberia), including a discussion on the morphology of some critical pollen types and non-pollen palynomorphs (NPPs). We found a strong correlation between vegetation and surface elevation and a fair correspondence between pollen deposition and vegetation. Distribution of NPPs reflects surface elevation well, with algal spores dominating deep spots and testate amoebae prevailing on higher spots. Peak pollen/spore values unrelated to high species coverages (e.g. of Salix, Betula, Sphagnum, Poaceae) indicate that single plants within a population may cause the bulk of the pollen production. The absence of pollen of taxa with an important presence in the vegetation (e.g. Utricularia) must be attributable to low pollen productivity. Distributional patterns point at pollen transport by water in the polygon troughs/depressions. Our study shows that Arctic pollen records mainly reflect short-distance vegetation patterns. Palaeosequences consequently allow accurate reconstruction of local microtopography and its dynamics, but should not be over-interpreted in terms of changing (over)regional vegetation patterns and associated drivers.

Distribution and Abundance of Airborne Palynomorphs in Aku, Enugu State, Nigeria

A study of airborne palynomorphs of Aku was carried out with the use of tauber pollen sampler from October to December, 2004. A total of 3,390 palynomorphs was recorded with the breakdown as follows: October, 1248; November, 1156 and December, 1526. Out of the counted palynomorphs, pollen grains constituted 2,125.The count of 736 pollen in October was followed by a decrease to 545 in November and a further increase to 844 in December. The pollen grains belonged to 20 families of flowering plants (17 dicotyledons and 3 monocotyledons) consisting of 20 genera. The result revealed dominance of wooded shrub grassland/woodland vegetation sub-type, relics of tropical lowland rainforest and secondary grassland. The taxa of both tropical lowland rainforest and secondary Grassland decreased from October to November and increased again in December. Fungi were the major spore contributors to the atmosphere and were dominated by the spores of S padicoides, Curvularia, Dreschlera/Helminthosporium and Nigrospora . Pollen grains were next to fungi in total abundance and were dominated by the pollen of; E laeis guineensis Jacq, Poaceae, Milicia excelsa Wild C.C. Berg, Irvingia wombolu Vermoesen, Syzygium guineense Engl. and Ageratum conyzoides L. December had a high influx of charred gramineae cuticles indicative of increased burning activities in the area. Fungal spores recorded per month had an inverse relationship with the monthly rainfall and relative humidity. Keywords : Distribution, Abundance, Airborne spore, Palynomorphs, Aku

Non-pollen palynomorphs as indicators of water quality in Lake Simcoe, Ontario, Canada

The distribution of non-pollen palynomorphs (NPP) in a core from Cook's Bay, Lake Simcoe, shows a response to changes in water quality accompanying agriculture, urbanization and industrialization. Low concentrations of nutrients in sediments with little non-arboreal pollen (NAP) record low disturbance prior to European settlement ∼1850s. These sediments are rich in desmids such as Cosmarium spp., Euastrum spp., and Staurastrum spp., an assemblage indicative of oligotrophic conditions. A decline in desmids together with an increase in dinoflagellates and thecamoebians up-core is consistent with increased nutrients. Abundant phytoliths in sediments that are relatively rich in Poaceae and other NAP records the draining of the Holland Marshes. A sharp increase in nutrient levels, together with a transition from high nitrite (NO2) to high nitrate (NO3) concentrations, records a sudden increase in biological oxygen demand leading to depletion of dissolved oxygen associated with the creation of polders in the 1920s and 1930s. A second influx of phytoliths immediately preceded the sharp rise in Ambrosia, recording rapid land clearing accompanying the five-fold post-World War II population boom in the Cook's Bay watershed. These Ambrosia-rich sediments are rich in metals and have high total phosphorus and NO3, with abundant Pediastrum spp. and Peridinium spp., notably Peridinium willei and Peridinium volzii, recording eutrophication. The abundance of the ciliate Codonella cratera and the difflugiid thecamoebians Cucurbitella tricuspis and Difflugia protaeiformis in palynological preparations as well as in washed thecamoebian samples from the upper part of the core records low dissolved oxygen associated with continued eutrophication of Cook's Bay.

TAPHONOMIC CONTROLS ON THE DISTRIBUTION OF PALYNOMORPHS IN TIDALLY INFLUENCED COASTAL DELTAIC SETTINGS

Palynomorph concentrations for water-column and sediment-water interface samples are presented for two coastal deltaic systems influenced by the range of tidal regimes to assess whether any taphonomic bias exists in pollen assemblages. The localities are the microtidally influenced Mobile-Tensaw River Delta, Alabama, United States, and the meso- to macrotidally influenced Rajang River Delta, Sarawak, East Malaysia. Mobile-Tensaw Delta data represent collections over a 13-month period; Rajang River Delta data represent sampling during the 1992 dry season. Results are reported for: (1) pollen concentration in suspended sediment loads and bottom sediments of distributary channels, and (2) selected spore-and-pollen frequencies in channels influenced by meso- and macrotidal processes. An increase in pollen concentration/liter occurs in all delta distributaries at water-column depth, and a positive relationship exists between pollen concentration and suspension load. Concentrations at the sediment-water interface are highest in tidally influenced areas where Heterogenous Aggregate Organic Matter (OM) clasts (floccules) dominate palynofacies assemblages, and statistically significant for Mobile-Tensaw lower delta plain sites. Hence, microtidal influence at the interface between fresh and brackish waters affects palynomorph concentration in bottom sediment and may be a function of flocculation induced by salinity flux. In contrast, concentrations are highest in bottom sediments of Rajang River distributaries where little active sediment transport occurs and tidal range is highest, and is due to several factors including a high proportion of Heterogenous Aggregate OM clasts. Additionally, the magnitude of tidal displacement impacts palynomorph distribution in the Rajang Delta, with mangrove pollen found in alluvial plain samples, a distance of

Spatial distribution of pollen grains and spores in surface sediments of Guanabara Bay, Rio de Janeiro, Brazil

Aiming to investigate the deposition of pollen grains and spores in Guanabara Bay, Rio de Janeiro State, 61 surface sediment samples were analyzed. The results showed that the current deposition of palynomorphs in surface sediments of Guanabara Bay represents the regional vegetation of this hydrographic basin. The differential distribution of palynomorphs followed a pattern influenced by bathymetry, tidal currents speed, discharge of numerous rivers, and by human activity. The dominance of representatives of Field Vegetation reflects the changes of the original flora caused by intense human activities in the region. The continued presence and richness of pollen types of rain forest in the samples indicates that their source area might be the vegetation from riparian border of rivers in the western sector of the Bay, where the mangrove vegetation is being preserved. The large amount of damaged palynomorphs may be related to abrasion that occurs during river transport, indicating removal or reworking from their areas of origin.

A palynological and sequence-stratigraphic study of Santonian–Maastrichtian strata from the Upper Magdalena Valley basin in central Colombia

This paper presents a sequence-stratigraphic interpretation from the palynological analysis and lithologic data of two outcrop sections on the NE flank of the Upper Magdalena Valley (UMV) basin primarily comprising the Santonian–Lower Maastrichtian interval. Important stratal horizons are identified in the northeastern part of the UMV basin and ages assigned to them. A cyclic pattern of palynomorph distribution was recognized in both sections and tied to the different stages of the stratigraphic chart. Spikes in abundance of spores accompanied by pollen characterize the lowstand systems tracts and are replaced by the occurrence of euryhaline dinoflagellate cysts (ceratioids and/or gymnodinioids) during the subsequent transgressive phase. Maximum flooding surfaces (MFS) are recognized by a sudden increase in open marine palynomorphs (peridinioids and/or gonyaulacoids) and the scarcity of terrestrial representatives. As sea level starts to fall, the gradual decrease in open marine dinoflagellates along with the occurrence of euryhaline dinoflagellate cysts and terrestrial representatives corresponds to highstand systems tracts. The sequence-stratigraphic interpretation from palynological analysis was correlated to the global sea-level curve allowing the identification of the Santonian–Campanian and Campanian–Maastrichtian boundaries. System tracts from supercycles ZC-3, ZC-4 and TA-1 were recognized from the palynological data.

Silurian to Early Devonian organic‐walled phytoplankton and miospores from Argentina: biostratigraphy and diversity trends

The distribution and diversity of marine palynomorphs, such as acritarchs and chlorophytes, and terrestrial palynomorphs, such as miospores, are controlled mainly by palaeoenvironmental and palaeogeographical conditions. Recently, global patterns of organic‐walled phytoplankton were illustrated for the Late Silurian to earliest Devonian based on data from different stratigraphic sections and palaeocontinents. Here, we analyze the Silurian and the Early Devonian diversity in the Argentinean Precordillera, Central Andean, and Chacoparanense basins. The evolution of the diversity is evaluated in a well‐constrained biostratigraphic framework, bearing in mind local palaeoenvironmental conditions and changes within each basin. Taking into account recently published and unpublished data from well‐dated sections, the biodiversity of Silurian phytoplankton seemingly increases upwards, reaching its maximum peak during the Ludlovian. However, palynomorphs are rarely recorded in Wenlockian strata, and the supposed Pridolian layers are not confidently well constrained. The first record of trilete spores in Argentina is Ludlovian, approximately 30 million years after their first appearance in the Late Ordovician. Palynomorph diversity increases in the Early Devonian, with a higher diversity of miospores than that of the marine phytoplankton. We interpret possible discrepancies in biodiversity trends of organic‐walled phytoplankton between Argentina and other regions, as related to the quantitatively and qualitatively disparity of data, as well as the lack of rigorous biostratigraphic and palaeoenvironmental assessments of the Argentinean basins. Copyright © 2011 John Wiley & Sons, Ltd.

Model selection using Minimal Message Length: an example using pollen data

In this paper we examine the use of the minimum message length criterion in the process of evaluating alternative models of data when the samples are serially ordered in space and implicitly in time. Much data from vegetation studies can be arranged in a sequence and in such cases the user may elect to constrain the clustering by zones, in preference to an unconstrained clustering. We use the minimum message length principle to determine if such a choice provides an effective model of the data. Pollen data provide a suitably organised set of samples, but have other properties which make it desirable to examine several different models for the distribution of palynomorphs within the clusters. The results suggest that zonation is not a particularly preferred model since it captures only a small part of the patterns present. It represents a user expectation regarding the nature of variation in the data and results in some patterns being neglected. By using unconstrained clustering within zones, we can recover some of this overlooked pattern. We then examine other evidence for the nature of change in vegetation and finally discuss the usefulness of the minimum message length as a guiding principle in model choice and its relationship to other possible criteria.

Contrasting Pliocene fluvial depositional systems within the rapidly subsiding South Caspian Basin; a case study of the palaeo-Volga and palaeo-Kura river systems in the Surakhany Suite, Upper Productive Series, onshore Azerbaijan

The South Caspian Basin contains major hydrocarbon reservoirs within the largely Early Pliocene Productive Series. This paper describes and contrasts outcrops of the uppermost ∼500 m of the series (the Surakhany Suite) deposited by two of the main fluvial systems that supplied the Azeri margin of the basin. Sedimentary facies and, for the first time from the Productive Series, palynological analyses document fluvial channel belt complexes, sheetflood overbank and flood plain to flood plain lake environments. The Productive Series on the Apsheron Peninsula, Azerbaijan, was supplied predominantly from the north by the palaeo-Volga river system. It displays an overall fining-upward trend, such that the Surakhany Suite at Lokbatan is dominated by mudstone. Siltstone and coarser-grained sediments make up 28% of the section. Channel bodies are on average 1.5 m thick and form 13% of the succession. In the sub-surface of the Apsheron Peninsula, ratty wireline log responses also indicate that siltstone and sandstone bodies are predominantly thin bedded, with SP-derived net-to-gross sand ratios of ∼0.35–0.40. The succession in the Kura Basin was sourced predominantly from the west by the palaeo-Kura river system. It displays a coarsening-upward trend, such that in the middle and upper Surakhany Suite at Babazanan siltstone and coarser sediments make up 52% of the section. It is characterised by numerous stacked and laterally continuous channel sandstone bodies that are on average 5.8 m thick and comprise 42% of the outcrop. In the sub-surface of the Kura Basin, wireline log responses of the Surakhany Suite have a blocky character and indicate SP-derived net-to-gross sand ratios of 0.26–0.38. These values are similar to calculated sandstone volumes at outcrop (44%). The palynological data, including multivariate analyses, show that the main controls on palynomorph distribution are the degree of fluvial or lacustrine influence, subaerial exposure and salinity. Despite their more lithic nature, Surakhany Suite sandstones derived from the palaeo-Kura river system along the Kurovdag-Babazanan-Neftchala trend have similar or better petrophysical properties than those derived from the palaeo-Volga river on the Apsheron Peninsula and its offshore continuation. This is probably due to their coarser-grain size. This, combined with their greater sandstone body thickness, would suggest that the axis of the Kura Basin forms the most promising part of the Azeri sector of the South Caspian Basin for exploration within the uppermost part of the Productive Series.

Palynomorph distribution in modern tropical deltaic and shelf sediments– mahakam delta, Borneo, Indonesia

The Mahakam Delta is a tropical, fluvio‐tidally dominated delta prograding onto a mixed siliciclastic‐carbonate shelf. Surface sediments were collected from 12 distinctive depositional environments extending from the head of the Mahakam Delta to the shelf edge. Organic matter was extracted from 200 samples by acid digestion, and seven palynomorph types (pollen, embryophyte spores, fungal spores, foraminiferal linings, copepod eggs, tintinnomorphs, and dinocysts) were identified and counted, and their percentages and concentrations calculated. Total organic carbon (TOC), lithology, and depositional environments were recorded for each sediment sample. The amounts of terrestrial palynomorphs in sediments can be explained by transport and depositional processes, and four groups of environments are identified (tidally influenced, detrital peat beach, lowland rain forest, and marine shelf)‐ Because of tidal flushing of the delta plain, pollen, embryophyte spores, fungal spores and soft plant debris from the soil litter are deposited together with clastic mud at slack‐water periods. As a result, all tidally‐influenced environments exhibit constant numbers of pollen, embryophyte spores, and fungal spores per unit of TOC. In lowland rain forest sediments, there is minor clastic dilution and the numbers of pollen and spores are three to 10 times higher per unit TOC than in tidally‐influenced sediments. In detrital peat beach and marine shelf sediments, the number of sporomorphs per unit TOC is lower than expected because of the selective removal of sporomorph‐sized particles by wave action and of dilution with autochthonous marine organic matter respectively. In contrast, the amounts of marine palynomorphs in sediments are related to the depositional environments. Relative amounts of marine palynomorphs increase gradually offshore, as both the sporomorph percentages and concentrations decrease simultaneously. Once in fully marine conditions, concentrations of marine palynomorphs are comparable in all shelf environments. The marine assemblages are mainly represented by Zooplankton (copepod eggs) and benthic protists (foraminiferal linings), the phytoplanktonic constituent (dinocyst) playing a subordinate role.

CRETACEOUS PALYNOLOGY (SPORES, POLLEN AND DINOFLAGELLATE CYSTS) OF THE SIQEIFA 1-X BOREHOLE, NORTHERN EGYPT

Diverse and well preserved palynofloras were recognized in the Lower Cretaceous succession penetrated by well Siqeifa 1-X in northern Egypt. Dinoflagellate cysts such as Subtilisphaera senegalensis was regarded, with the spores Impardecispora apiverrucata and Aequitriradites spinulosus, as important Berriasian to Barremian species. Afropollis operculatus/zonatus pollen and spores such as Balmeisporites holodictyus, Trilobosporites laevigatus and Duplexisporites generalis are diagnostic of Aptian. The lowest occurrences of the pollen Afropollis jardinus, the spore Crybelosporites pannuceus and elaterates such as Elaterosporites klaszii, Elaterocolpites castelainii and Elateroplicites africaensis characterize the Albian/lower Cenomanian interval. The palynofloras enabled the recognition of five spore-pollen and four dinoflagellate zones, which are correlated with regional records, mainly from Egypt and Libya. The vertical distribution of terrestrial and marine palynomorphs, along with palynodebris, reflects two regressive marginal marine cycles during Berriasian-Barremian and Albian-lower Cenomanian times whereas the Aptian witnessed a transgressive open marine (inner shelf) environment. A warm humid palaeoclimate was inferred during deposition of the investigated succession of the borehole, in contrast to the known warm arid to semi-arid climate, suggested for the Northern Gondwana Realm during Early Cretaceous times. This is probably due to the palaeogeographic position of Egypt during Early Cretaceous times or, to a local reason. Palynofloras from Siqeifa 1-X borehole, with Afropollis pollen and elaterates, are of North African aspect and share the broad characteristics of the Albian-Cenomanian Elaterates Province of Herngreen et al. (1996). Abundance of spores and araucariacean pollen are transitional features between those in North Gondwana and Southern Laurasia but, unlikely, typical transitional assemblages lack bisaccates conifers and have Gleicheniaceae spores.

Distribuição diferencial de palinomorfos na baía de Guanabara, Rio de Janeiro, Brasil

DIFFERENTIAL DISTRIBUTION OF PALYNOMORPHS IN THE GUANABARA BAY, RIO DE JANEIRO, BRAZIL. The present paper aims to characterize the modern depositional processes that control the palynomorph accumulation in several sectors of the Guanabara Bay. A total of 27 samples of surface sediments obtained inside the Guanabara Bay were collected and treated using palynological sieving methodology followed by the standard chemical treatment for Quarternary sediments. The results obtained showed a high percentual of fields (“Vegetacao Campestre”) elements and a high richness of pollen grains from the mixed rainforest (“Floresta Ombrofila” ). The differential distribution of palynomorphs followed a pattern that was influentiated by the bathymetry associated to the guidance of tide currents, which originated the highest concentration of palynomorphs in the deeper and topographical obstructed areas. The differential deposition in relation to the size of palynomorphs followed a model of accumulation of small palynomorphs inside the areas of high energy of the aquatic flow, and large size palynomorphs in quiet water areas and laterally to the discharge of the rivers.

Assessing mechanisms of environmental change: Palynological signals across the Late Ludlow (Silurian) positive isotope excursion ( δ13C, δ18O) on Gotland, Sweden

The Silurian is characterised by strong environmental changes, as indicated by several pronounced positive δ 13C and δ 18O excursions. The mechanisms responsible for these isotopic shifts are a matter of much debate. The purpose of the present study is a quantitative high-resolution evaluation of the palynomorph distribution across the Late Ludlow (Ludfordian) isotope excursion on Gotland. Marine and terrestrial palynomorphs have been chosen as palaeoenvironmental indicators because they are widely distributed and exceptionally well preserved. Moreover, the combined analysis of marine and terrestrial palynomorphs allows the reconstruction of contemporaneous palaeoenvironmental change in the marine and terrestrial realms. To correlate our results with the carbon isotope stratigraphy, we have sampled only localities with published isotope data from diagenetically unaltered brachiopod shells. Our results show that fluctuations in the composition of the acritarch assemblages are closely correlated with the stable isotope development. Low abundances of acritarchs occur in times of high stable isotope values and vice versa, indicating that an increase in marine productivity cannot have been the reason for the positive δ 13C excursion. The results are in good agreement with climatic models for the Silurian assuming alternating humid and arid climatic conditions in low latitudes. Times of high stable isotope values correspond to arid climatic conditions in low latitudes, with low input of terrestrial nutrients resulting in impoverished acritarch and conodont communities, whereas times of low stable isotope values correlate with humid climate, high nutrient input, and abundant and diverse acritarch communities. The major change in acritarch communities took place during the increase of the stable isotope values after hemipelagic planktonic or nektonic organisms (graptolites, conodonts) have been affected. This indicates that environmental changes connected with the stable isotope excursion first affected deeper-water settings and later the photic zone. The absolute abundance of terrestrial spores closely mirrors the marine δ 13C and δ 18O development, showing that both the marine and the terrestrial realm were synchronously affected by the climatic changes. The high abundance of spores during the isotope excursion might be explained by increased aeolian input.

Acritarch distribution along an inshore–offshore transect in the Gorstian (lower Ludlow) of Gotland, Sweden

To better understand palaeoecological signatures in Palaeozoic acritarch assemblages, the distribution of palynomorphs has been quantitatively studied in eight localities from the Gorstian, lower Ludlow (Late Silurian) of Gotland, Sweden. The localities are situated along an inshore–offshore transect comprising shallow marine lagoonal environments to distal shelf facies. Process-bearing acritarchs and sphaeromorphs constitute the main components within the palynomorph assemblages. The lateral distribution of palynomorphs exhibits characteristic features at three different levels as follows. (1) With regard to the overall composition of the palynomorph assemblages, the abundance of process-bearing acritarchs increases towards the distal shelf, while the abundance of sphaeromorphs decreases. (2) At the generic level, the acritarchs Micrhystridium and Dilatisphaera are more abundant in the proximal facies, while Evittia, Percultisphaera and Oppilatala are more common in distal environments. (3) At an infrageneric level, Micrhystridium morphotypes with shorter processes are mainly present in proximal environments, while those with longer and ramified processes occur in more distal shelf environments. The palynomorph distribution along the inshore–offshore transect highlights the potential of acritarchs and prasinophytes as palaeoenvironmental indicators.

Dispersed organic matter in samples from the western continental shelf of Southern Africa: palynofacies assemblages and depositional environments of Late Cretaceous and younger sediments

The composition and distribution of dispersed microscopic organic matter particles (phytoclasts) and palynomorphs in sediments and sedimentary rocks reflect factors that influenced their production in their original environments, transport to depositional sites, burial, and post-depositional changes. Thus, they can be used as proxies for reconstructing provenance, temporal and spatial paleoenvironmental conditions, and diagenetic changes. In this study, phytoclasts and palynomorphs in 55 spot samples from Upper Cretaceous, Eocene, Miocene and uppermost Pleistocene sediments on the western continental shelf of Namibia and South Africa were examined. They were used to test lateral depositional facies inferred from unpublished micropaleontological analysis, and to decipher any stratigraphic trends in the distribution of the organic particles in the sediments. Thirteen types of phytoclasts and palynomorphs were identified and analyzed in two ways: visually with basic quantitative techniques and statistically with two multivariate techniques. Three components, namely amorphous organic matter, wood, and black debris, were visually and statistically significant. Average linkage cluster analysis of these three components and discrete changes in the amounts of marine palynomorphs and other terrigenously derived organic material, such as spores and pollen, brown-black fragments, and plant tissues, delineated seven palynofacies assemblages. By contrast, principal components analysis revealed two groups of samples based on the amounts of amorphous organic matter and wood. Five groups of samples (referred to as associations) were identified visually from the pattern of organic matter distribution and compared with the statistical results. A palynofacies depositional model is proposed to re-evaluate the fluvial to inner shelf settings previously inferred for the sediments. Some clear stratigraphic trends were obvious in both sets of results, such as the dominance of amorphous organic matter in Turonian, Coniacian, and uppermost Pleistocene sediments, and higher percentages of black debris in the older sediments. These trends appear to be controlled more by provenance and depositional conditions than by age. The dominance of amorphous organic matter in several uppermost Pleistocene sediments (deposited during a global fall in sea level) were attributed to in-situ physical and biological degradation of mostly marine algal material in an inner shelf setting.

Palynological and sequence stratigraphic analysis of the Napo Group in the Pungarayacu 30 well, Sub-Andean Zone, Ecuador

The study of palynomorphs and calcareous nannofossils from the Albian–Campanian Napo Group in the Pungarayacu 30 well in the Subandean Zone of Ecuador has led to a new biostratigraphic framework revealing the existence of several hiatuses for this area. The palynological and palynofacies data are used together with other fossils and lithological evidence to define a sequence stratigraphic framework. The distribution of palynomorphs and palynofacies indicates a strong terrestrial input for the lower part of the Napo Group (Napo Basal and Lower Napo formations). In the upper part (Middle and Upper Napo formations), terrestrial input is reduced and a restricted marine environment with several dysoxic–anoxic intervals can be inferred. The hydrocarbons present in the well studied have traditionally been regarded as locally sourced. However, several lines of evidence (TAS, Tmax and VR) prove the immature stage of the source rock in this borehole as well as in a larger area.

Population-based analysis and graphic interpretation of fossil palynomorph records from Palynodata: taxonomic and biostratigraphic implications

Palynodata is a comprehensive database of the occurrences of pre-Quaternary palynomorphs, encompassing over 20 000 publications. Taxa are assumed to have distributions in time and space which are localized to a region around a central point, and, in the idealized case, can be visualized as a bell-shaped curve. A palynological study can be imagined as drawing a sample from each taxon’s time/space distribution. The probability of recording any taxon is partly a function of its abundance at the sampled point in the distribution. A comprehensive database such as Palynodata should allow approximation of the underlying population distribution of the taxon. Retrievals show that useful information is recovered from Palynodata, although there are errors and inadequacies in the database, of which the chief is the generalized study locality record. A computer program, Palynoplot, produces graphic plots of retrievals from Palynodata, allowing improved recognition of the patterns and problems in the database. Images of the database may have future applications for palynological taxonomy, paleoclimatology, paleoecology, modelling of palynomorph distributions, and possibly plate tectonic reconstruction.