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Andrew J Patience - One of the best experts on this subject based on the ideXlab platform.
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relationships between organo mineral supply and early diagenesis in the Lacustrine Environment a study of surficial sediments from the lac du bouchet haute loire france
Quaternary Science Reviews, 1996Co-Authors: Andrew J Patience, Elisabeth Lallierverges, Patrick Alberic, A Desprairies, Nicolas TribovillardAbstract:The relationships between organo-mineral composition and early diagenetic processes in surface (< 50 cm) sediments from the Lac du Bouchet (Haute Loire, France) are presented. Parallel pore-water studies reveal downcore increases in dissolved organic carbon, inorganic carbon and CH4, illustrating the dominant methanogenetic degradation, but also highlighting regions of enhanced degradation due to sulphate reduction (confirmed by solid phase sulphur and pyrite distributions). Three sedimentary facies are observed: IA (0–25 cm) where the majority of compaction and degradation of the organic matter by diagenesis occurs in the absence of any significant change in the type of organic material or sedimentation rate; IB (25–40 cm) characterised by an increased grain size and diatom abundance; II (below 40 cm), whose base dates at 2500 ± 350 BP (i.e. within the Sub-Atlantic) shows high organic carbon contents and large grain size. Autochthonous amorphous organic matter is the dominant petrographical organic component, whereas pedogenetic (allochthonous) amorphous organic matter is slightly enriched in facies II and IA. This is coincident with the disappearance of the spores and pollen and suggests a greater continental runoff from the surrounding basin at these times. Proportions of kaolinite, chlorite and illite content do not vary greatly, indicating that the detrital input has not changed significantly over the last 2500 years. Downcore decreases in the SiAl curve (proxy for biogenic silica) parallel those of total organic carbon suggesting the dissolution of solid phase silica over time. The anthropogenic deforestation and consequent greater nutrient runoff into the oligotrophic lake encouraged an increased production of diatoms around 30 cm. The increased sedimentation rate at the beginning of the Sub-Atlantic (facies II), as a result of greater continental runoff due to installation of present climatic conditions, enhanced the preservation of the organic material by reducing the dia-genetic effects and by increasing the proportion of diagenetically inert and relatively resistant organic matter. These findings underline the critical role that bulk sedimentation rate and the nature of organic matter play in the final determination of sediment composition, both in terms of input and in post-depositional degradation.
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organic fluxes and early diagenesis in the Lacustrine Environment the superficial sediments of the lac du bouchet haute loire france
Lecture Notes in Earth Sciences Berlin Springer Verlag, 1995Co-Authors: Andrew J Patience, Elisabeth Lallierverges, Abdelfettah Sifeddine, Patrick Alberic, Bernard GuilletAbstract:Superficial sediments from the Lac du Bouchet were analysed to study the degradation processes which affect sedimentary organic matter in an oligotrophic Lacustrine Environment. This was undertaken by the study of the evolution of the organic matter composition, in terms of both early diagenesis and any possible variations in organic inputs. The petrographical study of the resistant organic matter shows that some marked variations in the type, nature and abundance of organic inputs have occurred through time over the last 2500 years. The geochemical study of the bulk organic matter and the distribution of alkalisoluble components indicate that the effects of early diagenesis are only visible when the organic inputs are unchanged (<1400 years). Due to the very low sedimentation rates, methanogenesis seems only to affect the autochthonous (algal, phytoplanktonic) organic matter which consists of a degraded and amorphous organic matter, whereas the organic matter deriving from the surrounding basin has been partially or totally degraded before its deposition.
Nicolas Tribovillard - One of the best experts on this subject based on the ideXlab platform.
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relationships between organo mineral supply and early diagenesis in the Lacustrine Environment a study of surficial sediments from the lac du bouchet haute loire france
Quaternary Science Reviews, 1996Co-Authors: Andrew J Patience, Elisabeth Lallierverges, Patrick Alberic, A Desprairies, Nicolas TribovillardAbstract:The relationships between organo-mineral composition and early diagenetic processes in surface (< 50 cm) sediments from the Lac du Bouchet (Haute Loire, France) are presented. Parallel pore-water studies reveal downcore increases in dissolved organic carbon, inorganic carbon and CH4, illustrating the dominant methanogenetic degradation, but also highlighting regions of enhanced degradation due to sulphate reduction (confirmed by solid phase sulphur and pyrite distributions). Three sedimentary facies are observed: IA (0–25 cm) where the majority of compaction and degradation of the organic matter by diagenesis occurs in the absence of any significant change in the type of organic material or sedimentation rate; IB (25–40 cm) characterised by an increased grain size and diatom abundance; II (below 40 cm), whose base dates at 2500 ± 350 BP (i.e. within the Sub-Atlantic) shows high organic carbon contents and large grain size. Autochthonous amorphous organic matter is the dominant petrographical organic component, whereas pedogenetic (allochthonous) amorphous organic matter is slightly enriched in facies II and IA. This is coincident with the disappearance of the spores and pollen and suggests a greater continental runoff from the surrounding basin at these times. Proportions of kaolinite, chlorite and illite content do not vary greatly, indicating that the detrital input has not changed significantly over the last 2500 years. Downcore decreases in the SiAl curve (proxy for biogenic silica) parallel those of total organic carbon suggesting the dissolution of solid phase silica over time. The anthropogenic deforestation and consequent greater nutrient runoff into the oligotrophic lake encouraged an increased production of diatoms around 30 cm. The increased sedimentation rate at the beginning of the Sub-Atlantic (facies II), as a result of greater continental runoff due to installation of present climatic conditions, enhanced the preservation of the organic material by reducing the dia-genetic effects and by increasing the proportion of diagenetically inert and relatively resistant organic matter. These findings underline the critical role that bulk sedimentation rate and the nature of organic matter play in the final determination of sediment composition, both in terms of input and in post-depositional degradation.
Patrick Alberic - One of the best experts on this subject based on the ideXlab platform.
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sorption of organic matter on clay minerals in aquatic system influence on sedimentary organic preservation an example of a Lacustrine Environment lac pavin france
GFA-the Clay Minerals Society, 2006Co-Authors: Sylvain Drouin, Patrick Alberic, J L Robert, Mohammed Boussafir, Aude DurandAbstract:Sorption of organic molecules on clay surfaces in aquatic Environment influence organic sedimentation fluxes to bottom water and to sediment. It is well known that physical and chemical interactions produce the flocculation of organo-mineral complexes. Flocculation increases the density of sedimentary organic fractions and decreases the risks of oxidation and/or bacterial recycling, during transfer across the water column. Other studies, based on analyses of organic matter in sediments, revealed also that direct contacts between clay surfaces and organic molecules influence molecule availability to benthic fauna and bacteria. Many studies conclude that mineral sorption can be considered as one of the preservation mechanisms, leading to incorporation of metabolisable organic matter in sediments. The most part of these studies based their conclusions on analyses of sediments but never fully considered sorption processes resulting to organic matter preservation. Many questions in this topic remain unresolved. Does sorption of organic molecules on clay minerals can occur in the water column, i.e. before sedimentation ? Which organic molecules can be fixed on clays? What is the reactivity of these organo-mineral complexes in deep water? Does interaction can be considered as an efficient process for organic molecules protection, leading transport of organic matter from the dynamic water column to sediments? The aims of this work are first to test the possible in situ sorption of organic molecules on clay minerals, in a Lacustrine Environment, and secondly to test the stability of the organo-clay complexes formed under these conditions. In this respect, the behaviour of natural organic matter in presence of synthetic saponites (high- and low-charge Na-smectites) has been studied in oxic and anoxic levels of an oligotrophic meromictic crater lake (Lac Pavin, Massif Central, France). Clay samples were positioned in traps, closed by two membranes, allowing only circulation of dissolved organic matter. Interactions were interrupted on the spot, after 3, 10 and 21 days. Bulk chemical analyses showed the presence of organic carbon, associated with clays after interaction with the water lake. Low-charge saponites present higher organic carbon concentrations than high-charges, suggesting the non-prominence of cation bridge linkages between organic molecules and clay surfaces. Molecular pyro-GC/MS investigations, performed on clays, revealed the sorption of n- and iso- fatty acids, alkanes, alkenes and alcohols, in significant amounts. The molecular GC/MS analyses of organic extracts carried out on waters emphasized the lack of selectivity during fixation, since the same molecular fractions are present in waters and on clay surfaces. X-ray diffraction analyses, performed on the two saponites, proved the lack of molecular intercalation in clay mineral structure. ESCA analyses showed a loss of sodium in the interlayer space of the two saponites, and its probable substitution by divalent iron in anoxic deep water. Failure of extractions by saponification and organic solvents, tested on sorbed molecules, indicates the strong stability of the assemblages between clays and organic molecules.
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relationships between organo mineral supply and early diagenesis in the Lacustrine Environment a study of surficial sediments from the lac du bouchet haute loire france
Quaternary Science Reviews, 1996Co-Authors: Andrew J Patience, Elisabeth Lallierverges, Patrick Alberic, A Desprairies, Nicolas TribovillardAbstract:The relationships between organo-mineral composition and early diagenetic processes in surface (< 50 cm) sediments from the Lac du Bouchet (Haute Loire, France) are presented. Parallel pore-water studies reveal downcore increases in dissolved organic carbon, inorganic carbon and CH4, illustrating the dominant methanogenetic degradation, but also highlighting regions of enhanced degradation due to sulphate reduction (confirmed by solid phase sulphur and pyrite distributions). Three sedimentary facies are observed: IA (0–25 cm) where the majority of compaction and degradation of the organic matter by diagenesis occurs in the absence of any significant change in the type of organic material or sedimentation rate; IB (25–40 cm) characterised by an increased grain size and diatom abundance; II (below 40 cm), whose base dates at 2500 ± 350 BP (i.e. within the Sub-Atlantic) shows high organic carbon contents and large grain size. Autochthonous amorphous organic matter is the dominant petrographical organic component, whereas pedogenetic (allochthonous) amorphous organic matter is slightly enriched in facies II and IA. This is coincident with the disappearance of the spores and pollen and suggests a greater continental runoff from the surrounding basin at these times. Proportions of kaolinite, chlorite and illite content do not vary greatly, indicating that the detrital input has not changed significantly over the last 2500 years. Downcore decreases in the SiAl curve (proxy for biogenic silica) parallel those of total organic carbon suggesting the dissolution of solid phase silica over time. The anthropogenic deforestation and consequent greater nutrient runoff into the oligotrophic lake encouraged an increased production of diatoms around 30 cm. The increased sedimentation rate at the beginning of the Sub-Atlantic (facies II), as a result of greater continental runoff due to installation of present climatic conditions, enhanced the preservation of the organic material by reducing the dia-genetic effects and by increasing the proportion of diagenetically inert and relatively resistant organic matter. These findings underline the critical role that bulk sedimentation rate and the nature of organic matter play in the final determination of sediment composition, both in terms of input and in post-depositional degradation.
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organic fluxes and early diagenesis in the Lacustrine Environment the superficial sediments of the lac du bouchet haute loire france
Lecture Notes in Earth Sciences Berlin Springer Verlag, 1995Co-Authors: Andrew J Patience, Elisabeth Lallierverges, Abdelfettah Sifeddine, Patrick Alberic, Bernard GuilletAbstract:Superficial sediments from the Lac du Bouchet were analysed to study the degradation processes which affect sedimentary organic matter in an oligotrophic Lacustrine Environment. This was undertaken by the study of the evolution of the organic matter composition, in terms of both early diagenesis and any possible variations in organic inputs. The petrographical study of the resistant organic matter shows that some marked variations in the type, nature and abundance of organic inputs have occurred through time over the last 2500 years. The geochemical study of the bulk organic matter and the distribution of alkalisoluble components indicate that the effects of early diagenesis are only visible when the organic inputs are unchanged (<1400 years). Due to the very low sedimentation rates, methanogenesis seems only to affect the autochthonous (algal, phytoplanktonic) organic matter which consists of a degraded and amorphous organic matter, whereas the organic matter deriving from the surrounding basin has been partially or totally degraded before its deposition.
Elisabeth Lallierverges - One of the best experts on this subject based on the ideXlab platform.
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relationships between organo mineral supply and early diagenesis in the Lacustrine Environment a study of surficial sediments from the lac du bouchet haute loire france
Quaternary Science Reviews, 1996Co-Authors: Andrew J Patience, Elisabeth Lallierverges, Patrick Alberic, A Desprairies, Nicolas TribovillardAbstract:The relationships between organo-mineral composition and early diagenetic processes in surface (< 50 cm) sediments from the Lac du Bouchet (Haute Loire, France) are presented. Parallel pore-water studies reveal downcore increases in dissolved organic carbon, inorganic carbon and CH4, illustrating the dominant methanogenetic degradation, but also highlighting regions of enhanced degradation due to sulphate reduction (confirmed by solid phase sulphur and pyrite distributions). Three sedimentary facies are observed: IA (0–25 cm) where the majority of compaction and degradation of the organic matter by diagenesis occurs in the absence of any significant change in the type of organic material or sedimentation rate; IB (25–40 cm) characterised by an increased grain size and diatom abundance; II (below 40 cm), whose base dates at 2500 ± 350 BP (i.e. within the Sub-Atlantic) shows high organic carbon contents and large grain size. Autochthonous amorphous organic matter is the dominant petrographical organic component, whereas pedogenetic (allochthonous) amorphous organic matter is slightly enriched in facies II and IA. This is coincident with the disappearance of the spores and pollen and suggests a greater continental runoff from the surrounding basin at these times. Proportions of kaolinite, chlorite and illite content do not vary greatly, indicating that the detrital input has not changed significantly over the last 2500 years. Downcore decreases in the SiAl curve (proxy for biogenic silica) parallel those of total organic carbon suggesting the dissolution of solid phase silica over time. The anthropogenic deforestation and consequent greater nutrient runoff into the oligotrophic lake encouraged an increased production of diatoms around 30 cm. The increased sedimentation rate at the beginning of the Sub-Atlantic (facies II), as a result of greater continental runoff due to installation of present climatic conditions, enhanced the preservation of the organic material by reducing the dia-genetic effects and by increasing the proportion of diagenetically inert and relatively resistant organic matter. These findings underline the critical role that bulk sedimentation rate and the nature of organic matter play in the final determination of sediment composition, both in terms of input and in post-depositional degradation.
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organic fluxes and early diagenesis in the Lacustrine Environment the superficial sediments of the lac du bouchet haute loire france
Lecture Notes in Earth Sciences Berlin Springer Verlag, 1995Co-Authors: Andrew J Patience, Elisabeth Lallierverges, Abdelfettah Sifeddine, Patrick Alberic, Bernard GuilletAbstract:Superficial sediments from the Lac du Bouchet were analysed to study the degradation processes which affect sedimentary organic matter in an oligotrophic Lacustrine Environment. This was undertaken by the study of the evolution of the organic matter composition, in terms of both early diagenesis and any possible variations in organic inputs. The petrographical study of the resistant organic matter shows that some marked variations in the type, nature and abundance of organic inputs have occurred through time over the last 2500 years. The geochemical study of the bulk organic matter and the distribution of alkalisoluble components indicate that the effects of early diagenesis are only visible when the organic inputs are unchanged (<1400 years). Due to the very low sedimentation rates, methanogenesis seems only to affect the autochthonous (algal, phytoplanktonic) organic matter which consists of a degraded and amorphous organic matter, whereas the organic matter deriving from the surrounding basin has been partially or totally degraded before its deposition.
Wan Hasiah Abdullah - One of the best experts on this subject based on the ideXlab platform.
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geochemical characteristics of crude oils their asphaltene and related organic matter source inputs from fula oilfields in the muglad basin sudan
Marine and Petroleum Geology, 2015Co-Authors: Yousif M Makeen, Wan Hasiah Abdullah, Mohammed Hail Hakimi, Yousif Taha Hadad, Osman M A Elhassan, Khairul Azlan MustaphaAbstract:Abstract Bulk geochemical characteristics of crude oils, coupled with geochemical analyses of reservoir oil asphaltenes from Fula oilfields in the Muglad Basin, have provided information on source organic matter input, depositional Environment and the correlation between these crude oils and their potential source rocks in the basin. Only one oil family is present within the Fula oilfields as indicated by biomarker and non-biomarker parameters. The Fula oils are characterized by moderate API gravity, low sulphur and moderate trace metal (Ni, V) contents, and high wax contents. This suggested that the oils were generated from source rock that was deposited in a principally Lacustrine Environment. This is supported by bulk geochemical characteristics and biomarker compositions. A variety of biomarker–specific parameters obtained from n -alkanes, regular isoprenoids, terpanes and steranes indicate that the Fula oils were generated predominantly from algae-derived organic matter that was deposited in a Lacustrine Environment which then experienced a slight seawater influence under suboxic to relatively anoxic conditions. These oils were generated from source rock with a wide range of thermal maturity ranging from early to peak oil window. The biomarker characteristics of these oils are consistent with those of the early Cretaceous Abu Gabra shales. The oil-source rock relationship is also demonstrated by similarities in the structural moieties of the Fula oil asphaltene and the Abu Gabra shale kerogens. The Pyrolysis GC of the analyzed Fula oil asphaltene indicates that the oils were derived from Type I-algal organic matter, consistent with paraffinic high wax oils.
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the origin type and preservation of organic matter of the barremian aptian organic rich shales in the muglad basin southern sudan and their relation to paleoEnvironmental and paleoclimate conditions
Marine and Petroleum Geology, 2015Co-Authors: Yousif M Makeen, Mohammed Hail Hakimi, Wan Hasiah AbdullahAbstract:BarremianeAptian organic-rich shales from Abu Gabra Formation in the Muglad Basin were analysed using geochemical and petrographic analyses. These analyses were used to define the origin, type of organic matters and the influencing factors of diagenesis, including organic matter input and preservation, and their relation to paleoEnvironmental and paleoclimate conditions. The bulk geochemical characteristics indicated that the organic-rich shales were deposited in a Lacustrine Environment with seawater influence under suboxic conditions. Their pyrolysis hydrogen index (HI) data provide evidence for a major contribution by Type I/II kerogen with HI values of >400 mg HC/g TOC and a minor Type II/III contribution with HI values <400 mg HC/g TOC. This is confirmed by kerogen microscopy, whereby the kerogen is characterized by large amounts of structured algae (Botryococcus) and structureless (amorphous) with a minor terrigenous organic matter input. An enhanced biological productivity within the photic zone of the water columns is also detected. The increased biological productivity in the organicrich shales may be related to enhanced semi-arid/humid to humid-warm climate conditions. Therefore, a high bio-productivity in combination with good organic matter preservation favoured by enhanced algae
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geochemical characterisation of early cretaceous Lacustrine sediments of bima formation yola sub basin northern benue trough ne nigeria organic matter input preservation paleoEnvironment and palaeoclimatic conditions
Marine and Petroleum Geology, 2015Co-Authors: Babangida Sarki M Yandoka, Wan Hasiah Abdullah, M B Abubakar, Adebanji Kayode Adegoke, Mohammed Hail HakimiAbstract:The Bima Formation is the oldest lithogenetic unit occupying the base of the Cretaceous successions in the Yola Sub-basin of the Northern Benue Trough. It is differentiated into Lower (B1), Middle (B2) and Upper (B3) Bima Members. Integrated organic and inorganic geochemical studies were applied on the Lacustrine sediments of the Bima Formation with the aim of reconstructing the palaeodepositional Environment and organic matter input in response to climate and tectonism. The analysed sediments were deposited in a freshwater Lacustrine Environment with a low-salinity stratified water column and suboxic to relatively anoxic conditions, as indicated by the bulk geochemical parameters. The biomarkers provide evidence for a contribution of aquatic algae and microorganisms, with a significant amount of terrigenous organic matter input. The preservation of the organic matter is possibly attributed to the stratified water column with low salinity and suboxic to relatively anoxic conditions. Based on the geochemistry of major and trace elements, the sediments were deposited during semi-arid climatic conditions within passive continental margin setting. This agrees with the tectonic events in the West and Central African Rift System (WCARS) during the Early Cretaceous period.
