Jurassic sequences have long been considered the key source rocks in the Norwegian Sea. However, ... more Jurassic sequences have long been considered the key source rocks in the Norwegian Sea. However, in the Møre and Vøring Basins, these intervals are likely to be exhausted of any hydrocarbon generation potential due to deep burial and corresponding high maturity. An integrated geochemical and basin modelling investigation was therefore carried out to explore the potential for younger deepwater plays on this part of the Norwegian Continental Shelf. Evaluation of key source rock characteristics including richness, kerogen type and maturity, provided an initial appraisal of Cretaceous sources, which indicated the potential for both oil and gas generation, whilst optical maturity data indicated immatureearly oil window maturity throughout most of the drilled locations. Many hydrocarbon samples from the deepwater wells exhibit very different geochemical compositions compared to hydrocarbons associated with Jurassic sources. For example, stable carbon isotope compositions of fluids and sta...
Abstract—Hopanoids bound into the insoluble organic matter (kerogen) of Recent sediments from a f... more Abstract—Hopanoids bound into the insoluble organic matter (kerogen) of Recent sediments from a freshwater lake (Priest Pot) and an anoxic sulphidic fjord (Framvaren) were released by hydropyrolysis and examined by gas chromatography-mass spectrometry. Bound hopanoids are present in high concentration (190–1400 �g/g TOC) and represent 22 to 86 % of the total analysable hopanoids (i.e., bound and solventsoluble), this proportion increasing with depth in Framvaren Fjord. The hopanes generated by hydropyrolysis contain higher amounts of the C35, C32, and C30 homologues, reflecting the carbon number distribution of the bound hopanoids and indicating that both biohopanoids (C30 and C35) and their diagenetic products (dominated by C32) are incorporated into the kerogen on a timescale of only 0 to 350 years. Sequential (multiple temperature) hydropyrolysis experiments gave an indication of the relative strengths of bonds being cleaved in association with hopane generation: The hopanoids of...
Records of recent and past bacterial populations and processes can be preserved in sediments as b... more Records of recent and past bacterial populations and processes can be preserved in sediments as bacteriohopanepolyol (BHP) distributions. Due to the taxonomic variation expressed by the producer organisms (e.g. Rohmer, 1993) BHPs offer great potential as molecular markers and can be used to fingerprint hopanoid-producing bacterial community structure in modern environments. They also have the potential to provide a valuable record of past bacterial community structure in the geological record. Hopanoids occurring in sedimentary environments can no longer be considered to only be potential indicators of aerobic organisms and processes, having been identified in a range of anaerobic organisms (e.g. Blumenberg et al., 2006 and references therein). However, careful consideration of the fully intact BHP structures can still reveal insights into different bacterial communities (recent and past). Whilst some structures are known to have a wide range of potential source organisms others hav...
The major biomarker compounds in surface (0.95 meters below seafloor [mbsf]) and deep (579.92 mbs... more The major biomarker compounds in surface (0.95 meters below seafloor [mbsf]) and deep (579.92 mbsf) sediment samples from the Benguela Current coastal upwelling system off Lüderitz, Namibia (Leg 175 Hole 1084A), have been identified and quantified. Lipids of marine origin (especially long-chain alkenones) dominate the solvent-soluble extracts of both samples with minor constituents of terrestrially derived lipids. The paleoenvironmental significance of the more labile biomarker distributions (sterols) is limited by losses from depth-related diagenetic transformations. These losses may have led to the relative enrichment of the more refractory biomarkers (alkenones) with depth.
A series of diahopanes and a second, unknown, early-eluting series of triterpanes are reported in... more A series of diahopanes and a second, unknown, early-eluting series of triterpanes are reported in lacustrine oil samples from three different basins. We suggest that these compounds, together with 18a (H) 30-norneohopane, show distributions which vary with the salinity of the depositional environment.
A suite of black shales, calcareous shales and limestones, representing the Toarcian anoxic event... more A suite of black shales, calcareous shales and limestones, representing the Toarcian anoxic event (Jurassic, ~ 192 Ma), was collected from a 14-m length of core taken from the Belluno Trough, northern Italy, and examined in detail to assess variations in depositional environment during this interval. Geochemical and optical data indicate organic matter of algal and bacterial origin, with only trace contribution from terrestrial sources. Detailed biological marker data, interpreted with the aid of multivariate statistics, demonstrate fluctuations in primary producers and bacterial populations during black shale deposition. The onset of the anoxic event was not abrupt, but characterized by an apparent gradual development of anoxia and consequent enhanced organic-matter preservation. Different hopane biomarkers proved especially useful in recognizing preservation potential in the section, and correlate well with other "preservation" indicators. Increased oxygenation at the end of the event may have been associated with changes in primary productivity.
Hopanoic acids were found in all but the two most mature of a suite of 30 Triassic to Cretaceous ... more Hopanoic acids were found in all but the two most mature of a suite of 30 Triassic to Cretaceous sedimentary rocks. Their carbon number distributions generally maximise at C 32 , consistent with hopanoic acids found in modern sediments. The extent of isomerisation (measured ...
... Isolated anaerobic hydrocarbon degrading bacteria/archaea have also exhibited pronounced subs... more ... Isolated anaerobic hydrocarbon degrading bacteria/archaea have also exhibited pronounced substrate specificities (Widdel and Rabus, 2001) and the complex alteration of oils is the work of various specialised reservoir/region specific micro-organisms acting in concert during ...
A molecular stratigraphic approach is applied to a suite of sediment samples from Hole 686B in th... more A molecular stratigraphic approach is applied to a suite of sediment samples from Hole 686B in the Peru upwelling area to address past changes in sea-surface temperatures, biomass composition, marine productivity, and the supply of terrestrial organic matter. A complex history of sea-surface temperatures is revealed in the alkenone unsaturation index (U 3^) , particularly over the last 350,000 yr, probably reflecting increased intensity of coastal upwelling above this site. Changes in the relative contributions from marine and terrestrial sources of organic matter throughout the sediment sequence are revealed and discussed.
This study describes the molecular composition of the solvent-extractable organic matter of sedim... more This study describes the molecular composition of the solvent-extractable organic matter of sediment samples from the Peru upwelling area, collected from Hole 686B, Ocean Drilling Program (ODP) Leg 112. The postulated biological sources of individual lipids are discussed, and their concentrations calculated for a representative sediment sample. The solvent-soluble organic matter is dominated by lipids of marine origin, derived from
Jurassic sequences have long been considered the key source rocks in the Norwegian Sea. However, ... more Jurassic sequences have long been considered the key source rocks in the Norwegian Sea. However, in the Møre and Vøring Basins, these intervals are likely to be exhausted of any hydrocarbon generation potential due to deep burial and corresponding high maturity. An integrated geochemical and basin modelling investigation was therefore carried out to explore the potential for younger deepwater plays on this part of the Norwegian Continental Shelf. Evaluation of key source rock characteristics including richness, kerogen type and maturity, provided an initial appraisal of Cretaceous sources, which indicated the potential for both oil and gas generation, whilst optical maturity data indicated immatureearly oil window maturity throughout most of the drilled locations. Many hydrocarbon samples from the deepwater wells exhibit very different geochemical compositions compared to hydrocarbons associated with Jurassic sources. For example, stable carbon isotope compositions of fluids and sta...
Abstract—Hopanoids bound into the insoluble organic matter (kerogen) of Recent sediments from a f... more Abstract—Hopanoids bound into the insoluble organic matter (kerogen) of Recent sediments from a freshwater lake (Priest Pot) and an anoxic sulphidic fjord (Framvaren) were released by hydropyrolysis and examined by gas chromatography-mass spectrometry. Bound hopanoids are present in high concentration (190–1400 �g/g TOC) and represent 22 to 86 % of the total analysable hopanoids (i.e., bound and solventsoluble), this proportion increasing with depth in Framvaren Fjord. The hopanes generated by hydropyrolysis contain higher amounts of the C35, C32, and C30 homologues, reflecting the carbon number distribution of the bound hopanoids and indicating that both biohopanoids (C30 and C35) and their diagenetic products (dominated by C32) are incorporated into the kerogen on a timescale of only 0 to 350 years. Sequential (multiple temperature) hydropyrolysis experiments gave an indication of the relative strengths of bonds being cleaved in association with hopane generation: The hopanoids of...
Records of recent and past bacterial populations and processes can be preserved in sediments as b... more Records of recent and past bacterial populations and processes can be preserved in sediments as bacteriohopanepolyol (BHP) distributions. Due to the taxonomic variation expressed by the producer organisms (e.g. Rohmer, 1993) BHPs offer great potential as molecular markers and can be used to fingerprint hopanoid-producing bacterial community structure in modern environments. They also have the potential to provide a valuable record of past bacterial community structure in the geological record. Hopanoids occurring in sedimentary environments can no longer be considered to only be potential indicators of aerobic organisms and processes, having been identified in a range of anaerobic organisms (e.g. Blumenberg et al., 2006 and references therein). However, careful consideration of the fully intact BHP structures can still reveal insights into different bacterial communities (recent and past). Whilst some structures are known to have a wide range of potential source organisms others hav...
The major biomarker compounds in surface (0.95 meters below seafloor [mbsf]) and deep (579.92 mbs... more The major biomarker compounds in surface (0.95 meters below seafloor [mbsf]) and deep (579.92 mbsf) sediment samples from the Benguela Current coastal upwelling system off Lüderitz, Namibia (Leg 175 Hole 1084A), have been identified and quantified. Lipids of marine origin (especially long-chain alkenones) dominate the solvent-soluble extracts of both samples with minor constituents of terrestrially derived lipids. The paleoenvironmental significance of the more labile biomarker distributions (sterols) is limited by losses from depth-related diagenetic transformations. These losses may have led to the relative enrichment of the more refractory biomarkers (alkenones) with depth.
A series of diahopanes and a second, unknown, early-eluting series of triterpanes are reported in... more A series of diahopanes and a second, unknown, early-eluting series of triterpanes are reported in lacustrine oil samples from three different basins. We suggest that these compounds, together with 18a (H) 30-norneohopane, show distributions which vary with the salinity of the depositional environment.
A suite of black shales, calcareous shales and limestones, representing the Toarcian anoxic event... more A suite of black shales, calcareous shales and limestones, representing the Toarcian anoxic event (Jurassic, ~ 192 Ma), was collected from a 14-m length of core taken from the Belluno Trough, northern Italy, and examined in detail to assess variations in depositional environment during this interval. Geochemical and optical data indicate organic matter of algal and bacterial origin, with only trace contribution from terrestrial sources. Detailed biological marker data, interpreted with the aid of multivariate statistics, demonstrate fluctuations in primary producers and bacterial populations during black shale deposition. The onset of the anoxic event was not abrupt, but characterized by an apparent gradual development of anoxia and consequent enhanced organic-matter preservation. Different hopane biomarkers proved especially useful in recognizing preservation potential in the section, and correlate well with other "preservation" indicators. Increased oxygenation at the end of the event may have been associated with changes in primary productivity.
Hopanoic acids were found in all but the two most mature of a suite of 30 Triassic to Cretaceous ... more Hopanoic acids were found in all but the two most mature of a suite of 30 Triassic to Cretaceous sedimentary rocks. Their carbon number distributions generally maximise at C 32 , consistent with hopanoic acids found in modern sediments. The extent of isomerisation (measured ...
... Isolated anaerobic hydrocarbon degrading bacteria/archaea have also exhibited pronounced subs... more ... Isolated anaerobic hydrocarbon degrading bacteria/archaea have also exhibited pronounced substrate specificities (Widdel and Rabus, 2001) and the complex alteration of oils is the work of various specialised reservoir/region specific micro-organisms acting in concert during ...
A molecular stratigraphic approach is applied to a suite of sediment samples from Hole 686B in th... more A molecular stratigraphic approach is applied to a suite of sediment samples from Hole 686B in the Peru upwelling area to address past changes in sea-surface temperatures, biomass composition, marine productivity, and the supply of terrestrial organic matter. A complex history of sea-surface temperatures is revealed in the alkenone unsaturation index (U 3^) , particularly over the last 350,000 yr, probably reflecting increased intensity of coastal upwelling above this site. Changes in the relative contributions from marine and terrestrial sources of organic matter throughout the sediment sequence are revealed and discussed.
This study describes the molecular composition of the solvent-extractable organic matter of sedim... more This study describes the molecular composition of the solvent-extractable organic matter of sediment samples from the Peru upwelling area, collected from Hole 686B, Ocean Drilling Program (ODP) Leg 112. The postulated biological sources of individual lipids are discussed, and their concentrations calculated for a representative sediment sample. The solvent-soluble organic matter is dominated by lipids of marine origin, derived from
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