No description available.

The study examines sediments of the Productive Series from the western South Caspian Basin. The main goal of this work is to reconstract provenance of the sediments and its relation to the climatic variability during the deposition of the Productive Series. The Productive Series is divided into a lower and upper division. The Russian Platform was the main sediment source area for the Lower Division. Three different sediment source areas were determined for the Upper Division: the Russian Platform was sediment source area for the Absheron Peninsula; the Greater Caucasus was the main sediment source area for the South Absheron Offshore Zone and the Lesser Caucasus was the main sediment source area for the Baku Archipelago. The sediments of the Lower Division have variable smectite and illite concentrations which indicate climate change between humid and arid conditions in the Russian Platform. The Upper Division of the Productive Series from the Absheron Peninsula is characterised by high amounts of illite. It suggests physical weathering under arid climatic condition on the Russian Platform at the time of deposition. Variation of the smectite and illite assemblages of the Upper Division from the South Absheron Offshore Zone probably indicate that the climate alternated between humid and arid conditions in the Greater Caucasus. The low amount of the TOC ratios in the Productive Series are associated with arid climatic condition in the Russian Platform and the Greater Caucasus. The much higher TOC/TN ratios (>35) indicate that sediments of the Productive Series were impacted by oil. However the low TOC/TN ratios (<12) in some intervals of the Productive Series suggest an aquatic source for an organic matter.

Based upon the examination of the palynostratigraphy of 28 well sections and 6 multi-well studies, the Westphalian sequences in the Southern North Sea Carboniferous Basin are divided into 7 biozones and 12 sub-biozones. These are related, via the known regional northwest European palynostratigraphy, to the chronostratigraphic units of the Westphalian. Analysis of 164 palynological samples from Westphalian sections in the Murdoch Gas Field wells 44/22-1,44/22-3 and 44/22-4, coupled with the recognition of diagnostic macrofossil faunas indicative of the Vanderbeckei Marine Band, allows the direct calibration of part of the palynostratigraphic classification with the chronostratigraphy. Palynological assemblages from these wells contain significant numbers of acritarch and miospore taxa interpreted as being reworked from Lower Palaeozoic, Devonian and early Namurian sediments, possibly during multiple phases of reworking. Assemblages also contain unusually old examples of striate disaccate and monocolpate pollen. One new genus (Ala rasmospo rites) and eighteen new species (Auroraspora? pickerillensis, Dibolisporites ranunculioides, Elaterites anfractus, Endosporites pygmaeus, Hymenospora murdochensis, Knoxisporites biceps, Kraeuselisporites crassus, K. pseudoornates, Marasmosporites semiesus, Neoraistrickia exigua, N. virgultorum, Pityosporites inaequus, Protohaploxypinus masonii, Raistrickia parvula, Savitrisporites semotus, Spelaeotriletes oppletus, S. bulboides and Vestispora dubia) are described.

No description available.

Nearly thirty C20, C25, and C30 highly branched isoprenoid (HBI) hydrocarbons have been detected, sometimes in high concentrations, in recent freshwater, estuarine, coastal and hypersaline sediments, and water column particulate matter from numerous locations worldwide. The parent structures have been proved but only a few of the double bond positions have been established. The assignment of C21, C22 and C26 homologues and other C20 and C25 isomers, remains tentative. A wide body of evidence suggests that the compounds are biogenic in origin, with algae and possibly bacteria the most likely source organisms. A few of the compounds have been identified in field samples of algae but none have been reported in laboratory cultured biota. The alkenes with more than two double bonds appear to be rapidly removed from the hydrocarbon fraction in most sediments, whereas the alkanes and monoenes seem to be more resistant to biodegradation and hence occur in some more ancient sediments and oils. There is evidence that some of the alkenes react rapidly with sulphur to form either S-containing HBI heterocycles or become bound within macromolecular aggregates both found in sediments and some oils. The compounds, both as hydrocarbons and S-containing analogues, may prove useful environmental indicators once the sources and exact structures of more of them have been established. In the literature the structural elucidation of C25 and C30 alkenes has been based mainly on the analysis of their hydrogenation products. However, some authors concluded that the alkenes are cyclic since some could not be fully hydrogenated. The structure of a C25 HBI diene was proven to be a cyclic by hydrogenation studies and GC and GCMS analyses which showed the HBI compound to be fully saturated. The isolation and characterisation of synthetic alkenes resulted in the assignment, or partial assignment, of structures to four C20, six C25 and four C30 monoenes. The formation of novel monoenes via isomerisation reactions has also been achieved. The compounds form a valuable database of chromatographic and spectroscopic information for the assignment of sedimentary alkenes but the importance of isolation and micro-ozonolysis has been emphasised. Synthetic HBI alkenes were used to assign structures and partial structures to naturally occurring HBI hydrocarbons in three sediments. Other monoenes (both with methylene double bonds) were isolated from the sediments and characterised using spectroscopic and micro-ozonolysis data. The widespread occurrence of C20 and C23 HBI hydrocarbons in Tamar sediments and associated algae (macrophytes and diatoms), the large variation in isotopic composition evident for the C20 monoene, and the seasonal sedimentary distribution all suggest two possible sources for the HBI hydrocarbons; microalgae and/or heterotrophic bacteria. Investigation of the distribution of hydrocarbons from the Peru upwelling area confirmed the rapid decrease in concentration of C25 HBI alkenes with depth. A mixture of HBI monoenes was successfully incorporated into melanoidins but not detected in the humic acid pyrolysate which implied that incorporation of HBI alkenes into accreting humic substances was not a major mechanism of diagenesis of HBI alkenes. This study has extended present knowledge of the structures of HBI monoenes and has suggested two possible biological sources. There is still much to be learned about HBI polyenes and the subject is proving to be a fruitful area for further research into biomarker potential. Some possible future approaches are suggested.

No description available.

No description available.

Partly laminated sediments on the upper continental slope (200-600 m) off central Peru contain a diverse assemblage of fish debris, diatoms, and the remains of a variety of other nektonic, planktic, and benthic organisms. Approximately 97 percent of the fish scales recovered from the best preserved cores come from the anchoveta (79 percent) , Peruvian hake (16 percent) , and sardine (2 percent). Most of the diatoms belong to the genera Chaetoceros, Skeletonema, Thalassionema, Thalassiosira, Coscinodiscus, and Rhizosolenia. A discontinuous sedimentary record at 11°S. and 13°S. shows that the species composition of diatom and fish debris assemblages has changed very little in the past 15,000 years. However, the relative abundance of diatom species and genera, and to a lesser extent, fish species and genera, has fluctuated throughout the Holocene. These fluctuations may be attributed to changes of primary and secondary productivity in the overlying water column and to subsequent chemical and physical alteration of the depositional environment. An explanation of Holocene upwelling and productivity was developed based on the distribution of fish debris, diatoms, and silicoflagellates in sediments deposited during the Second Neoglacial Period (about 2700-1800 yr. B.P.) from core 7706-40 at 11°15'S. Floral and faunal assemblages, variously enriched in sardine and saury scales, diatoms of the species Rhizosolenia shrubsolei, R. bergonii, and Skeletonema costatum, and the silicoflagellate genera Dictyocha and Distephanus, suggest that periods of global atmospheric cooling were accompanied by both enhanced productivity and warmer surface water off the coast of Peru. Abundant sardine scales in sediments deposited during the close of the last ice age (11,700-11,400 yr. B.P.) and a tropical oceanic assemblage of diatoms (Coscinodiscus nodulifer, Asteromphalus spp., Rhizosolenia bergonii) deposited together with large numbers of Skeletonerna costatum and Rhizosolenia shrubsolei at 11°15'S. during the 'Little Ice Age' (200-500 yr. B.P.) are further evidence supporting the proposed explanation of Holocene upwelling and productivity patterns. Latitudinal compression of atmospheric and oceanic circulation in the South Pacific Ocean and a southward shifting Intertropical Convergence Zone are phenomena frequently attributed to climatic cooling. Intensified oceanic circulation and weakened southeast trade winds directly off Peru that may have resulted from the compressed and shifted circulation belts could have interacted to produce the paradoxical simultaneity of warm surface water and high productivity signals preserved in Peruvian marine sediments during some episodes of global atmospheric cooling. Further testing of this and competing hypotheses depends upon the availability of cores from the northern and southern reaches of the Peruvian continental margin that exhibit greater temporal continuity. / Graduation date: 1980

Graduation date: 1983

Graduation date: 1984