Studies on the pollen of New Zealand gymnosperms

This thesis has been particularly concerned with the interpretation of gymnosperm pollen percentages in modern and fossil pollen spectra in New Zealand. The morphology of the pollen of the indigenous gymnosperms was first studied to enable a correct identification of those types present in a sample to be made. Dacrydium pollen can be identified specifically except for D. bidwillii and D. biforme which are inseparable; Podocarpus pollen is readily separated into groups but further identification, especially within the P. totara complex, is difficult; the three species of Phyllocladus possess small pollen grains making specific identification impossible, especially with the light microscope; and Libocedrus plumosa and L. bidwillii are similar in all characters and thus inseparable. A new term, region of 'weakness', has been introduced for a feature previously not recognised in gymnosperm pollen. This region is adjacent to the dorsal roots of the bladders at the lateral margins of the cap and may have a function in harmomegathy. Modern pollen rain has been studied quantitatively in South Westland where pollen percentages in moss cushions were compared to a quantitative assessment of the local vegetation surrounding the sampling sites; qualitatively at various localities in the South Island and Stewart Island; and qualitatively and quantitatively at Lady Lake, North Westland, where surface lake sediments and moss cushions were analysed for their pollen content. Representation of pollen in surface samples is shown to be related to the pollination mechanism of each species present, the size of the plant and the structure of the local vegetation. Gymnosperm pollen is usually well represented because all species are anemophilous and thus produce large quantities of pollen. Most are trees (except Dacrydium laxifolium and Podocarpus nivalis) and their pollen is therefore released into the atmosphere above the vegetation from where it is effectively dispersed. The Aranuian vegetation at Lady Lake was studied and for the last 5700 radiocarbon years has been broadly similar to that of the present day. The pollen analysis provides evidence for complexity in the development of Aranuian vegetation in Westland and also suggests that, locally, fluctuations in lake level have been responsible for subtle changes in the vegetation

Morphology and ultrastructure of elater-bearing pollen from the Albian to Cenomanian of Brazil and Ecuador: implications for botanical affinity

The morphological range of elaterate pollen grains is reassessed on the basis of detailed light, scanning electron and transmission electron microscope analyses of representatives from upper Albian-Cenomanian sections in Brazil and Ecuador. Included in the elaterate complex are Alaticolpites, Elaterocolpites, Elateroplicites, Elateropollenites, Elaterosporites, Galeacornea, Pentapsis, Regalipollenites, Senegalosporites and Sofrepites. All possess elater-like protuberances, but are otherwise morphologically disparate. Ultrastructural analyses of three taxa, Elateroplicites africaensis, Elaterosporites klaszii and Sofrepites legouxiae, reveals granular-alveolate ektexine and wall organization comparable to that of gnetalean pollen and to fossil Equisetosporites/Ephedripites. A correlation exists between diversity/frequency levels of Elaterates and successive events in opening of the northern part of the South Atlantic Ocean. This is interpreted to reflect rapid diversification of the gnetalean sources of elaterate pollen in response to climatic perturbations associated with opening and enlargement of this ocean. The introduction and diversification of Elaterates coincides with early phases of angiosperm diversification, whereas extinction of the Elaterates-producing gnetalean group at the close of the Cenomanian heralded the rise to dominance of angiosperms in low latitudinal areas fringing the northern South Atlantic

Assessing palaeobathymetry and sedimentation rates using palynomaceral analysis: A study of modern sediments from the Gulf of Papua, offshore Papua New Guinea

© 2015 © 2015 AASP - The Palynological Society. Palynologists interested in better understanding the sedimentation and energy of depositional environments have often included studies of palynomaceral fragments, particularly when performing palynofacies analyses. Due to the difficult nature of classifying these fragments, researchers have developed numerous, often overlapping, classification schemes. These different schemes make it difficult to compare and contrast between research projects. Determining the appropriate scheme to apply when counting these fragments can be confusing, and application of these schemes can yield inconclusive results, especially when sedimentation and energy are in constant flux. A scheme of five categories, including brown wood (palynomaceral 1-2), leaf cuticle (palynomaceral 3), black debris (palynomaceral 4), structureless organic matter (SOM) and resin, is utilised here. It is applied to the analysis of 64 modern samples from the top 0-4 cm of sediment collected throughout the Gulf of Papua, Papua New Guinea. These samples span a suite of common marine depositional environments: river mouths and deltas, the proximal portion of the continental shelf dominated by a large clinoform, and turbidite and hemipelagic/pelagic deposits on the slope and in the deep ocean basin. Principal component analysis (PCA) confirms this simplified classification scheme provides an indirect means of assessing distance from shore and shelf-slope break, overall water depth and sediment accumulation rate, but other factors, such as processing technique, marine productivity, sediment source, time in transport and residence and bioturbation, are taken into account to fully explain distribution

Assessing palaeobathymetry and sedimentation rates using palynomaceral analysis: a study of modern sediments from the Gulf of Papua, offshore Papua New Guinea

© 2015 © 2015 AASP - The Palynological Society. Palynologists interested in better understanding the sedimentation and energy of depositional environments have often included studies of palynomaceral fragments, particularly when performing palynofacies analyses. Due to the difficult nature of classifying these fragments, researchers have developed numerous, often overlapping, classification schemes. These different schemes make it difficult to compare and contrast between research projects. Determining the appropriate scheme to apply when counting these fragments can be confusing, and application of these schemes can yield inconclusive results, especially when sedimentation and energy are in constant flux. A scheme of five categories, including brown wood (palynomaceral 1-2), leaf cuticle (palynomaceral 3), black debris (palynomaceral 4), structureless organic matter (SOM) and resin, is utilised here. It is applied to the analysis of 64 modern samples from the top 0-4 cm of sediment collected throughout the Gulf of Papua, Papua New Guinea. These samples span a suite of common marine depositional environments: river mouths and deltas, the proximal portion of the continental shelf dominated by a large clinoform, and turbidite and hemipelagic/pelagic deposits on the slope and in the deep ocean basin. Principal component analysis (PCA) confirms this simplified classification scheme provides an indirect means of assessing distance from shore and shelf-slope break, overall water depth and sediment accumulation rate, but other factors, such as processing technique, marine productivity, sediment source, time in transport and residence and bioturbation, are taken into account to fully explain distribution