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Thai T Phan - One of the best experts on this subject based on the ideXlab platform.
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rare earth elements and radiogenic strontium isotopes in carbonate minerals reveal diagenetic influence in shales and limestones in the appalachian basin
Chemical Geology, 2019Co-Authors: Thai T Phan, Alexandra J Hakala, Christina L Lopano, Shikha SharmaAbstract:Abstract Rare earth element (REE) signatures are often applied to interpret paleoenvironmental conditions in sedimentary basins, however the complicated diagenetic histories in dynamic depositional environments can affect interpretation of measured REE signatures. Prior studies on REE content in shales and limestones indicated that REE in specific mineral phases may provide unique information concerning diagenetic reactions occurring in sedimentary rocks during burial and compaction. Application of sequential extraction techniques to target REE signatures in specific mineral fractions may provide greater insight into the complex processes that occurred during diagenesis and Catagenesis. Thus, using this technique, this study provides a detailed account for REE, 87Sr/86Sr, and δ13C in the carbonate fraction of the Marcellus Shale and adjacent formations in the Appalachian Basin. A suite of 49 rock samples collected from two cores recovered from Monongalia County, West Virginia, USA was analyzed. The results showed that the carbonate concretions in calcareous shales and carbonate cements in black shales were very distinct. The REE plus yttrium (REY) were more concentrated in the carbonate concretions than in the carbonate cements. The carbonate concretions displayed REY patterns that are closely similar to modern seawater, while MREE-enrichment was observed in the carbonate cements. Likewise, the 87Sr/86Sr values in the carbonate concretions were similar to those measured for unaltered Middle Devonian carbonates, while the 87Sr/86Sr in the carbonate cements were much more radiogenic. This observation indicates that the carbonate cement could have been inherited radiogenic 87Sr expulsed from clays during illite-smectite transition. Overall, this study demonstrated two distinct processes involved with controlling the carbonate geochemistry within Appalachian Basin shales and limestones: one fraction displaying minimal diagenetic alteration relative to depositional conditions (carbonate concretions in calcareous shales and limestone carbonate in limestones), and another fraction displaying the evidence for extensive chemical alteration during illite-smectite transition and Catagenesis (carbonate cements in black shales). In addition, highly variable and significant enrichments of U and Mo demonstrate that the Union Spring member and the Lower Oatka Creek member of the Marcellus Shale in the southwestern Appalachian Basin (MSEEL site) were deposited under mainly anoxic environment whereas intermitted episodes of dysoxic to perhaps oxic conditions occurred during the deposition of the Upper Oatka Creek member.
Adel Arfaoui - One of the best experts on this subject based on the ideXlab platform.
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organic geochemical study of ypresian sediments at jebel ousselat tunisia
Geochemistry International, 2008Co-Authors: Adel Arfaoui, Mabrouk MontacerAbstract:This new study was carried out in order to accurately characterize the geochemical pattern of Ousselat organic-rich facies from the Ypresian basin in central-northern Tunisia. It has been found that the organic matter is located towards the end of diagenesis/beginning of Catagenesis. This assumption is supported by the relative low Tmax values (429–439°C) and by steranes maturity parameters such as C29 αα 20S/(20S + 20R), and C29 ββ/(ββ + αα). High HI values and the abundance of saturates (1–83%) compared to aromatics (2–27%) are unequivocal evidence of type-II organic matter as indicated by a high abundance of cholestane and the predominance of short-chain n-alkanes centred at n-C18 and at n-C20. Total organic carbon (TOC) content and petroleum potential values suggest that the Ypresian period corresponds to an anoxic event which led to the accumulation and preservation of large quantities of organic matter with high primary production. Due to their geochemical characteristics, the Lower Eocene facies represent a new potential source rocks in central-northern Tunisia.
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comparative study between rock eval pyrolysis and biomarkers parameters a case study of ypresian source rocks in central northern tunisia
Marine and Petroleum Geology, 2007Co-Authors: Adel Arfaoui, Mabrouk Montacer, Fekri Kamoun, Adel RiganeAbstract:Abstract Sedimentary rock samples from the Ypresian Basin, in central-northern Tunisia, were analyzed by two well-proven organic geochemical methods: Rock-Eval (RE) pyrolysis and gas chromatography–mass spectrometry (GC–MS) analysis. These techniques were uses to obtain independent parameters on organic matter composition, its thermal maturity, and environment of deposition. This study reveals a close concordance between Rock-Eval pyrolysis data and polycyclic biomarkers parameters such as hopanes and steranes. RE pyrolysis in conjunction with GC–MS analysis show that the Ypresian Basin sediments contain a variable but notable organic-rich facies during the Ypresian and prove an unequivocal evidence for Type-II organic matter, which lies dominantly prior to the peak stage of the conventional oil window (end of diagenesis-beginning of Catagenesis). The case study from the Ypresian Basin shows that these methods remain undoubtedly suitable for a good assessment of the petroleum potential of source rocks and rapid geochemical characterization of sedimentary organic matter.
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usefulness of rock eval pyrolysis liquid chromatography and gc ms in the characterization of ypresian chaker organic matter central northern tunisia
Fuel Processing Technology, 2007Co-Authors: Adel Arfaoui, Mabrouk Montacer, Dorra MehdiAbstract:Abstract The present paper compares Rock-Eval pyrolysis (RE), liquid chromatography (L.C), and gas chromatography-mass spectrometry (GC–MS) data from a geochemical study of Jebel Chaker organic-rich facies, in central-northern Tunisia, in order to obtain independent parameters on organic matter source, composition, and thermal maturity. This study shows a clear evidence of planktonic organic matter as indicated by the hydrogen index, n-alkanes distribution, predominance of saturated, and the high concentration of cholestane. The thermal maturity of Ypresian organic matter was estimated by T max , abundance of hetero (N.S.O) compounds, and sterane geochemical parameters such as C 29 αα 20S / (20S + 20R) and C 29 ββ (ββ + αα) maturity ratios…, to be of low thermal maturity (end of diagenesis–beginning of Catagenesis). These data reveal a close concordance between RE, L.C., and GC/MS data, and show that these methods remain valuable and practical for geochemical characterization of sedimentary organic matter.
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geochemical characterization given by rock eval parameters and n alkanes distribution on ypresian organic matter at jebel chaker tunisia
Resource Geology, 2007Co-Authors: Adel Arfaoui, Mabrouk MontacerAbstract:Sedimentary rock samples from Jebel Chaker in the eastern part of the Ypresian basin in central-northern Tunisia were analyzed using various geochemical methods in order to decipher their organic signature. Examination of the distribution of total organic carbon (1.04–1.82%) suggests that the petroleum potential of Ypresian facies is not ignored in such area. The Ypresian episode permitted the accumulation of organic matter, which is typically marine plankton as indicated by the unimodal distribution of N-alkane at nC18 and by the predominance of the aliphatic hydrocarbons compared to the aromatics. It is concluded that the Ypresian organic matter is relatively immature, as indicated by the high content of polar compounds (3–67%) in bitumen. This conclusion is supported by the relative low Tmax values (433–438°C), suggesting that the organic matter is located towards the end of diagenesis and beginning of Catagenesis. These new results testify to the establishment of suboxic conditions that led to the accumulation and preservation of good quantities of organic matter in central-northern Tunisia during the Ypresian. Due to their geochemical characteristics, the Chaker facies represent new potential source rocks in central-northern Tunisia.
Murray R Gray - One of the best experts on this subject based on the ideXlab platform.
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Formation of Archipelago Structures during Thermal Cracking Implicates a Chemical Mechanism for the Formation of Petroleum Asphaltenes
2015Co-Authors: Ali H Alshareef, Alexander Scherer, Xiaoli Tan, Khalid Azyat, Jeffrey M Stryker, Rik R Tykwinski, Murray R GrayAbstract:A series of model compounds for the large components in petroleum, with molecular weights from 534 to 763 g/mol, was thermally cracked in the liquid phase at 365–420 °C to simulate Catagenesis over a very short time scale and reveals the selectivity and nature of the addition products. The pyrolysis of three types of compounds was investigated: alkyl pyrene, alkyl-bridged pyrene with phenyl or pyridine as a central ring group, and a substituted cholestane–benzoquinoline compound. Analysis of the products of reaction of each compound by mass spectrometry, high-pressure liquid chromatography, and gas chromatography demonstrated that a significant fraction of the products, ranging from 26 to 62 wt %, was addition products with molecular weights higher than that of the starting compounds. Nuclear magnetic resonance (NMR) spectroscopic analysis showed that the pyrene compounds undergo addition through the attached alkyl groups, giving rise to bridged archipelago products. These results imply that the same geochemical processes that generate the light components of petroleum, such as n-alkanes, simultaneously produce some of the most complex heavy components in the asphaltenes. Similarly, thermal cracking reactions during refinery processes, such as visbreaking and coking, will drive addition reactions involving the alkyl groups on large aromatic compounds
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formation of archipelago structures during thermal cracking implicates a chemical mechanism for the formation of petroleum asphaltenes
Energy & Fuels, 2011Co-Authors: Ali H Alshareef, Alexander Scherer, Xiaoli Tan, Khalid Azyat, Jeffrey M Stryker, Rik R Tykwinski, Murray R GrayAbstract:A series of model compounds for the large components in petroleum, with molecular weights from 534 to 763 g/mol, was thermally cracked in the liquid phase at 365–420 °C to simulate Catagenesis over a very short time scale and reveals the selectivity and nature of the addition products. The pyrolysis of three types of compounds was investigated: alkyl pyrene, alkyl-bridged pyrene with phenyl or pyridine as a central ring group, and a substituted cholestane–benzoquinoline compound. Analysis of the products of reaction of each compound by mass spectrometry, high-pressure liquid chromatography, and gas chromatography demonstrated that a significant fraction of the products, ranging from 26 to 62 wt %, was addition products with molecular weights higher than that of the starting compounds. Nuclear magnetic resonance (NMR) spectroscopic analysis showed that the pyrene compounds undergo addition through the attached alkyl groups, giving rise to bridged archipelago products. These results imply that the same geoc...
Mabrouk Montacer - One of the best experts on this subject based on the ideXlab platform.
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organic geochemical study of ypresian sediments at jebel ousselat tunisia
Geochemistry International, 2008Co-Authors: Adel Arfaoui, Mabrouk MontacerAbstract:This new study was carried out in order to accurately characterize the geochemical pattern of Ousselat organic-rich facies from the Ypresian basin in central-northern Tunisia. It has been found that the organic matter is located towards the end of diagenesis/beginning of Catagenesis. This assumption is supported by the relative low Tmax values (429–439°C) and by steranes maturity parameters such as C29 αα 20S/(20S + 20R), and C29 ββ/(ββ + αα). High HI values and the abundance of saturates (1–83%) compared to aromatics (2–27%) are unequivocal evidence of type-II organic matter as indicated by a high abundance of cholestane and the predominance of short-chain n-alkanes centred at n-C18 and at n-C20. Total organic carbon (TOC) content and petroleum potential values suggest that the Ypresian period corresponds to an anoxic event which led to the accumulation and preservation of large quantities of organic matter with high primary production. Due to their geochemical characteristics, the Lower Eocene facies represent a new potential source rocks in central-northern Tunisia.
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comparative study between rock eval pyrolysis and biomarkers parameters a case study of ypresian source rocks in central northern tunisia
Marine and Petroleum Geology, 2007Co-Authors: Adel Arfaoui, Mabrouk Montacer, Fekri Kamoun, Adel RiganeAbstract:Abstract Sedimentary rock samples from the Ypresian Basin, in central-northern Tunisia, were analyzed by two well-proven organic geochemical methods: Rock-Eval (RE) pyrolysis and gas chromatography–mass spectrometry (GC–MS) analysis. These techniques were uses to obtain independent parameters on organic matter composition, its thermal maturity, and environment of deposition. This study reveals a close concordance between Rock-Eval pyrolysis data and polycyclic biomarkers parameters such as hopanes and steranes. RE pyrolysis in conjunction with GC–MS analysis show that the Ypresian Basin sediments contain a variable but notable organic-rich facies during the Ypresian and prove an unequivocal evidence for Type-II organic matter, which lies dominantly prior to the peak stage of the conventional oil window (end of diagenesis-beginning of Catagenesis). The case study from the Ypresian Basin shows that these methods remain undoubtedly suitable for a good assessment of the petroleum potential of source rocks and rapid geochemical characterization of sedimentary organic matter.
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usefulness of rock eval pyrolysis liquid chromatography and gc ms in the characterization of ypresian chaker organic matter central northern tunisia
Fuel Processing Technology, 2007Co-Authors: Adel Arfaoui, Mabrouk Montacer, Dorra MehdiAbstract:Abstract The present paper compares Rock-Eval pyrolysis (RE), liquid chromatography (L.C), and gas chromatography-mass spectrometry (GC–MS) data from a geochemical study of Jebel Chaker organic-rich facies, in central-northern Tunisia, in order to obtain independent parameters on organic matter source, composition, and thermal maturity. This study shows a clear evidence of planktonic organic matter as indicated by the hydrogen index, n-alkanes distribution, predominance of saturated, and the high concentration of cholestane. The thermal maturity of Ypresian organic matter was estimated by T max , abundance of hetero (N.S.O) compounds, and sterane geochemical parameters such as C 29 αα 20S / (20S + 20R) and C 29 ββ (ββ + αα) maturity ratios…, to be of low thermal maturity (end of diagenesis–beginning of Catagenesis). These data reveal a close concordance between RE, L.C., and GC/MS data, and show that these methods remain valuable and practical for geochemical characterization of sedimentary organic matter.
-
geochemical characterization given by rock eval parameters and n alkanes distribution on ypresian organic matter at jebel chaker tunisia
Resource Geology, 2007Co-Authors: Adel Arfaoui, Mabrouk MontacerAbstract:Sedimentary rock samples from Jebel Chaker in the eastern part of the Ypresian basin in central-northern Tunisia were analyzed using various geochemical methods in order to decipher their organic signature. Examination of the distribution of total organic carbon (1.04–1.82%) suggests that the petroleum potential of Ypresian facies is not ignored in such area. The Ypresian episode permitted the accumulation of organic matter, which is typically marine plankton as indicated by the unimodal distribution of N-alkane at nC18 and by the predominance of the aliphatic hydrocarbons compared to the aromatics. It is concluded that the Ypresian organic matter is relatively immature, as indicated by the high content of polar compounds (3–67%) in bitumen. This conclusion is supported by the relative low Tmax values (433–438°C), suggesting that the organic matter is located towards the end of diagenesis and beginning of Catagenesis. These new results testify to the establishment of suboxic conditions that led to the accumulation and preservation of good quantities of organic matter in central-northern Tunisia during the Ypresian. Due to their geochemical characteristics, the Chaker facies represent new potential source rocks in central-northern Tunisia.
Shikha Sharma - One of the best experts on this subject based on the ideXlab platform.
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rare earth elements and radiogenic strontium isotopes in carbonate minerals reveal diagenetic influence in shales and limestones in the appalachian basin
Chemical Geology, 2019Co-Authors: Thai T Phan, Alexandra J Hakala, Christina L Lopano, Shikha SharmaAbstract:Abstract Rare earth element (REE) signatures are often applied to interpret paleoenvironmental conditions in sedimentary basins, however the complicated diagenetic histories in dynamic depositional environments can affect interpretation of measured REE signatures. Prior studies on REE content in shales and limestones indicated that REE in specific mineral phases may provide unique information concerning diagenetic reactions occurring in sedimentary rocks during burial and compaction. Application of sequential extraction techniques to target REE signatures in specific mineral fractions may provide greater insight into the complex processes that occurred during diagenesis and Catagenesis. Thus, using this technique, this study provides a detailed account for REE, 87Sr/86Sr, and δ13C in the carbonate fraction of the Marcellus Shale and adjacent formations in the Appalachian Basin. A suite of 49 rock samples collected from two cores recovered from Monongalia County, West Virginia, USA was analyzed. The results showed that the carbonate concretions in calcareous shales and carbonate cements in black shales were very distinct. The REE plus yttrium (REY) were more concentrated in the carbonate concretions than in the carbonate cements. The carbonate concretions displayed REY patterns that are closely similar to modern seawater, while MREE-enrichment was observed in the carbonate cements. Likewise, the 87Sr/86Sr values in the carbonate concretions were similar to those measured for unaltered Middle Devonian carbonates, while the 87Sr/86Sr in the carbonate cements were much more radiogenic. This observation indicates that the carbonate cement could have been inherited radiogenic 87Sr expulsed from clays during illite-smectite transition. Overall, this study demonstrated two distinct processes involved with controlling the carbonate geochemistry within Appalachian Basin shales and limestones: one fraction displaying minimal diagenetic alteration relative to depositional conditions (carbonate concretions in calcareous shales and limestone carbonate in limestones), and another fraction displaying the evidence for extensive chemical alteration during illite-smectite transition and Catagenesis (carbonate cements in black shales). In addition, highly variable and significant enrichments of U and Mo demonstrate that the Union Spring member and the Lower Oatka Creek member of the Marcellus Shale in the southwestern Appalachian Basin (MSEEL site) were deposited under mainly anoxic environment whereas intermitted episodes of dysoxic to perhaps oxic conditions occurred during the deposition of the Upper Oatka Creek member.