The lacustrine organic-rich shale in the Permian Lucaogou(LCG)Formation of the Jimsar Sag,Junggar Basin,is one of the main shale oil plays in China.In this paper,geological and geochemical research techniques were emp...The lacustrine organic-rich shale in the Permian Lucaogou(LCG)Formation of the Jimsar Sag,Junggar Basin,is one of the main shale oil plays in China.In this paper,geological and geochemical research techniques were employed to evaluate the geochemical variability of the lacustrine shale and the pro-duction of organic matter and its preservation conditions.The LcG Formation is characterized by its complex mineral compositions and a wide range of organic matter richness and quality.The presence of high proportions ofβ-carotane and C2g steranes,indicates that the organic matter mainly originated from phytoplankton and aquatic algal-bacterial organisms,especially cyanobacteria.This study found that the productivity of the Lower LCG Member(P2li)was highest,and the Middle LCG Member(P_(2)l_(2))was the lowest.During the deposition of the Lower LCG Member,the lake's bottom water was predominantly a reducing environment,and the degradation of organic matter was largely a result of bacterial sulfate reduction.During the deposition of the Middle and Upper LCG members,the lake's bottom water was mainly oxidizing,and the degradation of organic matter was likely to be caused by aerobic processes.Based on a comprehensive analysis of the origin and production of organic matter,as well as its depo-sitional environment and preservation conditions,two organic matter accumulation models were pro-posed to explain the distribution of the organic-rich shale.In model A,the high influx of volcanic ash released nutrients and brought abundant sulfate into the water,the accumulation of organic matter was mainly controlled by the preservation of organic matter,which was mainly controlled by BsR.In the model B,the influx of volcanic ash was small,organic matter was mainly degraded by oxygen and the accumulation of organic matter is mainly determined by the production of organic matter.展开更多
Colloform pyrite with core-rim texture is commonly deposited in carbonate platforms associated with the sulfide ores such as the Caixiashan Pb-Zn deposit.However,the genesis of colloform pyrite in Pb-Zn deposits,its g...Colloform pyrite with core-rim texture is commonly deposited in carbonate platforms associated with the sulfide ores such as the Caixiashan Pb-Zn deposit.However,the genesis of colloform pyrite in Pb-Zn deposits,its growth controls and their geological implication are insufficiently understood.Integration of in-situ trace element and SIMS sulfur isotopes has revealed geochemical variations among these pyrite layers.These colloform pyrite occur as residual phases of core-rim aggregates,the cores are made up of very fine-grained anhedral pyrite particles,with some rims being made up of fine-grained and poorlycrystallized pyrite,while the other rims were featured with euhedral cubic pyrite.which are cemented by fine-grained calcite and/or dolomite with minor quartz.Sulfur isotope analysis shows that some wellpreserved rims have negative δ^34 S values(-28.12‰to-0.49‰),whereas most of the cores and rims have positive δ^34 S values(>0 to+44.28‰;peak at+14.91‰).Integrating with the methane and sulfate were observed in previous fluid inclusion study,we suggest that the 34 S depleted rims were initially formed by bacteria sulfate reduction(BSR),whereas the positive δ^34 S values were resulted from the sulfate reduction driven by anaerobic methane oxidation(AOM).The well-developed authigenic pyrite and calcite may also support the reaction of AOM.Combined with petrographic observations,trace element composition of the colloform pyrite reveals the incorporation and precipitation behavior of those high abundance elements in the pyrite:Pb and Zn were present as mineral inclusion and likely precipitated before Fe,as supported by the time-resolved Pb-Zn signal spikes in most of the analyzed pyrite grains.Other metals,such as Hg,Co and Ni,may have migrated as chloride complexes and entered the pyrite lattice.Arsenic and Sb,generally influenced by complex-forming reactions rather than substitution ones,could also enter the pyrite lattice,or slightly predate the precipitation of colloform pyrite as mineral inclusions,which are controlled by their hydrolysis constant in the ore fluids.The colloform pyrite may have grown inward from the rims.The successive BSR reaction process would enrich H^32/2S in the overlying water column but reduce the metal content,the nucleation of these pyrite rims was featured by strongly negative sulfur isotopes.The following AOM process should be activated by deformation like the turbidity sediment of the mudstone as the sulfide deposition are associated with fault activities that caused the emission of methane migration upward and simultaneously replenishing the metal in the column.The higher AOM reaction rate and the higher metal supply(not only Fe.but with minor other metals such as Pb and Zn) caused by sediment movement enhanced the metal concentration within the pyrite lattice.展开更多
High-sulfur,heavy petroleum is widely occurring in the Tertiary lacustrine Jiyang sub-basin, Bohai Bay Basin.They are differentiated into two families based on the bulk properties and biomarker compositions.Family 1 i...High-sulfur,heavy petroleum is widely occurring in the Tertiary lacustrine Jiyang sub-basin, Bohai Bay Basin.They are differentiated into two families based on the bulk properties and biomarker compositions.Family 1 is characterized by high resins（40%-71%）and sulfur（2%-4%）,and low wax （l%-6%）,with n-alkanes removed by biodegradation,whereas family 2 is characterized by extremely abundant sulfur（3%-10%）,and high asphaltenes（7%-31%）and wax（2%-19%）,with no evidence of microbial attack.The oils of family 1 are distributed in the reservoir,lower than 1500 m throughout the sub-basin.Biomarker assemblages,such as low pristane/phytane ratios（1 Pr/Ph）and a high abundance of carotane,gammacerane,and dinosterane,suggest that they are derived from the calcareous mudstones and shales among the stratified,saline Es_4~u unit,in addition to the in situ biodegradation-concentrated sulfur content.However,the oils of family 2 are identified only in the western Zhanhua and eastern Chezhen depressions,with a depth deeper than 1700 m.Physical properties,together with biomarker ratios,including even-numbered n-alkanes,1 Pr/Ph,trace diasteranes,higher C35 homohopanes,and abundant dibenzothiophene series,with1 dibenzothiophene/phenanthrene,indicate an origin from carbonate source rocks.The X-ray diffraction analysis showed that the carbonate source rock is limited in the Es_4~u unit of the Bonan sag,which is different from most other source rocks in the same horizon.It is suggested that the high-sulfur,heavy oils are generated at the early stage of the oil window.Bacterial sulfate reduction might be responsible for the occurrence of sulfur species in the high-sulfur,heavy oils,while heavy biodegradation will enhance sulfur concentrations.展开更多
Nitrobenzene (NB) is frequently found in wastewaters containing sulfate and may affect biological sulfate reduction process, but information is limited on the responses of sulfate reduction efficiency and microbial co...Nitrobenzene (NB) is frequently found in wastewaters containing sulfate and may affect biological sulfate reduction process, but information is limited on the responses of sulfate reduction efficiency and microbial community to the increased NB contents. In this study, a laboratory-scale expanded granular sludge bed reactor was operated continuously to treat high-sulfate organic wastewater with increased NB contents. Results successfully demonstrated that the presence of more than 50 mg/L NB depressed sulfate reduction and such inhibition was partly reversible. Bath experiments showed that the maximum specific desulfuration activity (SDA) decreased from 135.80 mg SO4^2-/gVSS/d to 30.78 mg SO4^2-/gVSS/d when the NB contents increased from none to 400 mg/L. High-throughput sequencing showed that NB also greatly affected bacterial community structure. Bcicteroidetes dominated in the bioreactor. The abundance of Proteobacteria increased with NB addition while Firmicutes presented an opposite trend. Proteobacteria gradually replaced Finnicutes for the dominance in response to the increase of influent NB concentrations.The genus Desulfovibrio was the dominant sulfate-reducing bacteria (SRB) with absence or presence of NB, but was inhibited under high content of NB. The results provided better understanding for the biological sulfate reduction under NB stress.展开更多
The Fankou Pb-Zn deposit is a very important and famous deposit in China. The time of Pb-Zn enrichment has been debated for a long time in this deposit. A total of seventeen samples of three sections were taken from t...The Fankou Pb-Zn deposit is a very important and famous deposit in China. The time of Pb-Zn enrichment has been debated for a long time in this deposit. A total of seventeen samples of three sections were taken from the Fankou mine for the study of mineralization time and the mechanism of ore formation. The samples were analyzed by microscope, Soxhlet-extract, GC, and GC/MS methods. The results indicated that organic bulk parameters vary with the Pb-Zn contents in different samples and clearly were influenced by ore sulfide formation. Organically geochemical parameters (MPI 1, CPI) indicate that the paleotemperatures in the Fankou deposit are lower than 80℃ in all three sections. Sulfides in the wall rocks might occur mainly during synsedimentation or early diagenesis by BSR or partly by PR, rather than by TSR at such low temperatures, this stage may be the first mineralization stage. Sulfides near the faults might be formed by TSR after sedimentation, this stage may be the second mineralization stage.展开更多
Thrombolites are widespread in the Mesoproterozoic Wumishan Formation in the North China Platform.This study shows that they mainly concentrated in subtidal carbonate facies with relatively low hydrodynamic conditions...Thrombolites are widespread in the Mesoproterozoic Wumishan Formation in the North China Platform.This study shows that they mainly concentrated in subtidal carbonate facies with relatively low hydrodynamic conditions,rather than in intertidal zone as suggested previously.From the deep lower to the shallow upper subtidal facies,the thrombolites show evident changes in morphology from dominantly domal to tabular forms,likely suggestive of environmental controls on their morphogenesis and distribution.As the most important component in thrombolites,mesoclots typically consist of organic-rich micritic nuclei and organic-poor fibrous aragonite rims.Mesoclots may vary considerably in their morphology,but a type of specifically shaped mesoclots tends to concentrate predominantly in a particular group of thrombolites.The proportion of the fibrous aragonite rims in mesoclots decrease as the depositional environments become shallower,likely suggesting that the environmental changes also have controls on the internal fabrics of thrombolites.Putative filamentous bacterial colonies are well preserved in some aragonite fans in the matrix between mesoclots,invoking rapid precipitation and aragonite-supersaturated conditions in the ambient waters.It seems that a suboxic to anoxic environment,highly alkaline seawater and relatively low hydrodynamic conditions were among the important factors that facilitated the development and preservation of thrombolites in the Mesoproterozoic epeiric sea on the North China Platform.展开更多
基金supported by National Science Foundation for Young Scientists of China(Grant 41702143)Major basic science and technology projects of CNPC(2021DJ0206-03)。
文摘The lacustrine organic-rich shale in the Permian Lucaogou(LCG)Formation of the Jimsar Sag,Junggar Basin,is one of the main shale oil plays in China.In this paper,geological and geochemical research techniques were employed to evaluate the geochemical variability of the lacustrine shale and the pro-duction of organic matter and its preservation conditions.The LcG Formation is characterized by its complex mineral compositions and a wide range of organic matter richness and quality.The presence of high proportions ofβ-carotane and C2g steranes,indicates that the organic matter mainly originated from phytoplankton and aquatic algal-bacterial organisms,especially cyanobacteria.This study found that the productivity of the Lower LCG Member(P2li)was highest,and the Middle LCG Member(P_(2)l_(2))was the lowest.During the deposition of the Lower LCG Member,the lake's bottom water was predominantly a reducing environment,and the degradation of organic matter was largely a result of bacterial sulfate reduction.During the deposition of the Middle and Upper LCG members,the lake's bottom water was mainly oxidizing,and the degradation of organic matter was likely to be caused by aerobic processes.Based on a comprehensive analysis of the origin and production of organic matter,as well as its depo-sitional environment and preservation conditions,two organic matter accumulation models were pro-posed to explain the distribution of the organic-rich shale.In model A,the high influx of volcanic ash released nutrients and brought abundant sulfate into the water,the accumulation of organic matter was mainly controlled by the preservation of organic matter,which was mainly controlled by BsR.In the model B,the influx of volcanic ash was small,organic matter was mainly degraded by oxygen and the accumulation of organic matter is mainly determined by the production of organic matter.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41702067 and 41602067)National Key Research and Development Program of China(Grant No.2018YFC0603603)+1 种基金Natural Science Foundation of Guangdong Province(Grant No.2017A0303113246)the Fundamental Research Funds for the Central Universities(171gpy63 and 181gpy25)
文摘Colloform pyrite with core-rim texture is commonly deposited in carbonate platforms associated with the sulfide ores such as the Caixiashan Pb-Zn deposit.However,the genesis of colloform pyrite in Pb-Zn deposits,its growth controls and their geological implication are insufficiently understood.Integration of in-situ trace element and SIMS sulfur isotopes has revealed geochemical variations among these pyrite layers.These colloform pyrite occur as residual phases of core-rim aggregates,the cores are made up of very fine-grained anhedral pyrite particles,with some rims being made up of fine-grained and poorlycrystallized pyrite,while the other rims were featured with euhedral cubic pyrite.which are cemented by fine-grained calcite and/or dolomite with minor quartz.Sulfur isotope analysis shows that some wellpreserved rims have negative δ^34 S values(-28.12‰to-0.49‰),whereas most of the cores and rims have positive δ^34 S values(>0 to+44.28‰;peak at+14.91‰).Integrating with the methane and sulfate were observed in previous fluid inclusion study,we suggest that the 34 S depleted rims were initially formed by bacteria sulfate reduction(BSR),whereas the positive δ^34 S values were resulted from the sulfate reduction driven by anaerobic methane oxidation(AOM).The well-developed authigenic pyrite and calcite may also support the reaction of AOM.Combined with petrographic observations,trace element composition of the colloform pyrite reveals the incorporation and precipitation behavior of those high abundance elements in the pyrite:Pb and Zn were present as mineral inclusion and likely precipitated before Fe,as supported by the time-resolved Pb-Zn signal spikes in most of the analyzed pyrite grains.Other metals,such as Hg,Co and Ni,may have migrated as chloride complexes and entered the pyrite lattice.Arsenic and Sb,generally influenced by complex-forming reactions rather than substitution ones,could also enter the pyrite lattice,or slightly predate the precipitation of colloform pyrite as mineral inclusions,which are controlled by their hydrolysis constant in the ore fluids.The colloform pyrite may have grown inward from the rims.The successive BSR reaction process would enrich H^32/2S in the overlying water column but reduce the metal content,the nucleation of these pyrite rims was featured by strongly negative sulfur isotopes.The following AOM process should be activated by deformation like the turbidity sediment of the mudstone as the sulfide deposition are associated with fault activities that caused the emission of methane migration upward and simultaneously replenishing the metal in the column.The higher AOM reaction rate and the higher metal supply(not only Fe.but with minor other metals such as Pb and Zn) caused by sediment movement enhanced the metal concentration within the pyrite lattice.
基金Funds to support this research were provided by the National Science Foundation of China(no. 40703011)
文摘High-sulfur,heavy petroleum is widely occurring in the Tertiary lacustrine Jiyang sub-basin, Bohai Bay Basin.They are differentiated into two families based on the bulk properties and biomarker compositions.Family 1 is characterized by high resins（40%-71%）and sulfur（2%-4%）,and low wax （l%-6%）,with n-alkanes removed by biodegradation,whereas family 2 is characterized by extremely abundant sulfur（3%-10%）,and high asphaltenes（7%-31%）and wax（2%-19%）,with no evidence of microbial attack.The oils of family 1 are distributed in the reservoir,lower than 1500 m throughout the sub-basin.Biomarker assemblages,such as low pristane/phytane ratios（1 Pr/Ph）and a high abundance of carotane,gammacerane,and dinosterane,suggest that they are derived from the calcareous mudstones and shales among the stratified,saline Es_4~u unit,in addition to the in situ biodegradation-concentrated sulfur content.However,the oils of family 2 are identified only in the western Zhanhua and eastern Chezhen depressions,with a depth deeper than 1700 m.Physical properties,together with biomarker ratios,including even-numbered n-alkanes,1 Pr/Ph,trace diasteranes,higher C35 homohopanes,and abundant dibenzothiophene series,with1 dibenzothiophene/phenanthrene,indicate an origin from carbonate source rocks.The X-ray diffraction analysis showed that the carbonate source rock is limited in the Es_4~u unit of the Bonan sag,which is different from most other source rocks in the same horizon.It is suggested that the high-sulfur,heavy oils are generated at the early stage of the oil window.Bacterial sulfate reduction might be responsible for the occurrence of sulfur species in the high-sulfur,heavy oils,while heavy biodegradation will enhance sulfur concentrations.
基金the National Natural Science Foundation of China (Grant Nos. 51378251 and 51408298)National Key R&D Program of China (No. 2016YFE0112300).
文摘Nitrobenzene (NB) is frequently found in wastewaters containing sulfate and may affect biological sulfate reduction process, but information is limited on the responses of sulfate reduction efficiency and microbial community to the increased NB contents. In this study, a laboratory-scale expanded granular sludge bed reactor was operated continuously to treat high-sulfate organic wastewater with increased NB contents. Results successfully demonstrated that the presence of more than 50 mg/L NB depressed sulfate reduction and such inhibition was partly reversible. Bath experiments showed that the maximum specific desulfuration activity (SDA) decreased from 135.80 mg SO4^2-/gVSS/d to 30.78 mg SO4^2-/gVSS/d when the NB contents increased from none to 400 mg/L. High-throughput sequencing showed that NB also greatly affected bacterial community structure. Bcicteroidetes dominated in the bioreactor. The abundance of Proteobacteria increased with NB addition while Firmicutes presented an opposite trend. Proteobacteria gradually replaced Finnicutes for the dominance in response to the increase of influent NB concentrations.The genus Desulfovibrio was the dominant sulfate-reducing bacteria (SRB) with absence or presence of NB, but was inhibited under high content of NB. The results provided better understanding for the biological sulfate reduction under NB stress.
基金support to this study by the NSFC Projects (Nos.40173004 and 40773040) is gratefully acknowledged
文摘The Fankou Pb-Zn deposit is a very important and famous deposit in China. The time of Pb-Zn enrichment has been debated for a long time in this deposit. A total of seventeen samples of three sections were taken from the Fankou mine for the study of mineralization time and the mechanism of ore formation. The samples were analyzed by microscope, Soxhlet-extract, GC, and GC/MS methods. The results indicated that organic bulk parameters vary with the Pb-Zn contents in different samples and clearly were influenced by ore sulfide formation. Organically geochemical parameters (MPI 1, CPI) indicate that the paleotemperatures in the Fankou deposit are lower than 80℃ in all three sections. Sulfides in the wall rocks might occur mainly during synsedimentation or early diagenesis by BSR or partly by PR, rather than by TSR at such low temperatures, this stage may be the first mineralization stage. Sulfides near the faults might be formed by TSR after sedimentation, this stage may be the second mineralization stage.
基金supported by the Ministry of Science and Technology(No.2011CB808806)the National Natural Science Foundation(No.41272039 and No.40921062) of China
文摘Thrombolites are widespread in the Mesoproterozoic Wumishan Formation in the North China Platform.This study shows that they mainly concentrated in subtidal carbonate facies with relatively low hydrodynamic conditions,rather than in intertidal zone as suggested previously.From the deep lower to the shallow upper subtidal facies,the thrombolites show evident changes in morphology from dominantly domal to tabular forms,likely suggestive of environmental controls on their morphogenesis and distribution.As the most important component in thrombolites,mesoclots typically consist of organic-rich micritic nuclei and organic-poor fibrous aragonite rims.Mesoclots may vary considerably in their morphology,but a type of specifically shaped mesoclots tends to concentrate predominantly in a particular group of thrombolites.The proportion of the fibrous aragonite rims in mesoclots decrease as the depositional environments become shallower,likely suggesting that the environmental changes also have controls on the internal fabrics of thrombolites.Putative filamentous bacterial colonies are well preserved in some aragonite fans in the matrix between mesoclots,invoking rapid precipitation and aragonite-supersaturated conditions in the ambient waters.It seems that a suboxic to anoxic environment,highly alkaline seawater and relatively low hydrodynamic conditions were among the important factors that facilitated the development and preservation of thrombolites in the Mesoproterozoic epeiric sea on the North China Platform.
