This study recovered the Guadalupian conodont faunas from Shangsi （上寺） Section in Northeast Sichuan （四川）. Four genera and nine species were identified, and three conodont zones were recognized and established;...This study recovered the Guadalupian conodont faunas from Shangsi （上寺） Section in Northeast Sichuan （四川）. Four genera and nine species were identified, and three conodont zones were recognized and established; they include Jinogondolella nankingensis Zone, J. aserrata Zone, and J. postserrata Zone. The Roadian and Wordian boundary is set in the interval 5 m from the top of Bed 86 by the first appearance of the conodont J. aserrata. The Wordian and Capitanian boundary is set in the interval 2.3 m from the top of the Bed 95 by the first appearance ofJ. postserrata. Most of the specimens demonstrated low color alteration index （CAI） as 1.5-3, indicating that most part of the Maokou （茅口） Formation may have the suitable thermal conditions for the formation of oil source rocks.展开更多
On the basis of establishment of radiolarian biostratigraphy and conodont biostratigraphy, a radiolarian Albaillella fauna in the transitional environment from Guadalupian to Lopingian Series in Permian was found at a...On the basis of establishment of radiolarian biostratigraphy and conodont biostratigraphy, a radiolarian Albaillella fauna in the transitional environment from Guadalupian to Lopingian Series in Permian was found at a pelagic chert section in southeast Guangxi, South China. Radiolarian Albaillella is one of the most sensitive biology to the transitional environment. The Albaillella fauna shows an ecological evolutionary process from Guadalupian to Lopingian: declined stage-recovery stage-flourishing stage. The study of characteristics of the Albaillella fauna in the transitional environment may provide more information, not only for the subdivision and correlation of a high-resolution biostratigraphy, but also for influence of radiolarian Albaillella fauna on the pre-Lopingian mass extinction.展开更多
The Gujingling （古井岭） Section in Xiaodong （小董）, Guangxi （广西） Zhuang Autonomous Region, China, consists of cherts and siliceous siltstones, which belongs to the Bancheng （板城）Formation of the Qinzhou （...The Gujingling （古井岭） Section in Xiaodong （小董）, Guangxi （广西） Zhuang Autonomous Region, China, consists of cherts and siliceous siltstones, which belongs to the Bancheng （板城）Formation of the Qinzhou （钦州） allochthon. Three successive radiolarian assemblage-zones related to the Guadalupian （Middle Permian） appear in the section in the following ascending order： Pseudoalbaillella sp. aff. Pseudoaibailleila longicornis-Pseudoalbaillella fusiformis, Follicucuilus monacanthus, and Follicucuilus scholasticus-Foilicucullus porrectus. The radiolarian content in this section is generally greater than that of sponge spicules. The radiolarian fauna commonly consists of abundant Albaillellaria and spherical radiolaria with minor Latentifistularia and Entactinaria. The sponge fauna is composed mainly of hexactinellids with minor demosponges. These siliceous fossil faunal features, comparable with those in a deep basin of the western belt of the Phosphoria Basin in the western United States, indicate that the Bancheng Formation in the Gujingling Section was deposited in a basin deeper than 1 000 m. The siliceous siltstones in the section are characterized by inclusion of silt-sized quartz and no inclusion of sand-sized materials, suggesting that the Gujingling Section was located at least a few hundred kilometers from the South China Block in the Guadalupian.展开更多
The end-Paleozoic biotic crisis is characterized by two-phase mass extinctions;the first strike,resulting in a large decline of sessile benthos in shallow marine environments,occurred at the end-Guadalupian time.In or...The end-Paleozoic biotic crisis is characterized by two-phase mass extinctions;the first strike,resulting in a large decline of sessile benthos in shallow marine environments,occurred at the end-Guadalupian time.In order to explore the mechanism of organisms' demise,detailed analyses of depositional facies,fossil record,and carbonate carbon isotopic variations were carried out on a Maokou-Wujiaping boundary succession in northwestern Sichuan,SW China.Our data reveal a negative carbon isotopic excursion across the boundary;the gradual excursion with relatively low amplitude(2.15‰) favors a long-term influx of isotopically light 12 C sourced by the Emeishan basalt trap,rather than by rapid releasing of gas hydrate.The temporal coincidence of the beginning of accelerated negative carbon isotopic excursion with onsets of sea-level fall and massive biotic demise suggests a cause-effect link between them.Intensive volcanic activity of the Emeishan trap and sea-level fall could have resulted in detrimental environmental stresses and habitat loss for organisms,particularly for those benthic dwellers,leading to their subsequent massive extinction.展开更多
A mixed siliciclastic-carbonate system that responds to changes in Permian climate and subsequent carbonate platform evolution is investigated using microscopic details of the Middle Permian Amb Formation(Fm.),in Saiy...A mixed siliciclastic-carbonate system that responds to changes in Permian climate and subsequent carbonate platform evolution is investigated using microscopic details of the Middle Permian Amb Formation(Fm.),in Saiyiduwali section,Khisor Range,northern Pakistan.Thin sections were made from rocks throughout the stratigraphic section of the Amb Fm.and analyzed with an emphasis on carbonate and clastic microfacies,and the latter interpreted within the existing chronostratigraphic framework.Outcrop observations reveal that the units comprise coarse-grained,channelized,ripplemarked,and burrowed sandstone and sandy,fossiliferous limestone with minor marls and shale intercalations,suggesting deposition in a subaqueous tide-dominated delta to beach barrier.Based on the determined seven microfacies coupled with outcrop observation,the Amb Fm.was deposited in a tide-influenced subaqueous delta to middle shelf environment under fluctuating sea level.The deposition of compositionally mature sandstone in the lower part of the formation suggests reworking of detritus from the rift shoulders and an adjacent source area with an ambient warm and humid climate.The stratal mixing of carbonates and compositionally mature siliciclastic units in the middle part suggest deposition under tectonic and climate-induced terrigenous and carbonate fluxes to the basin.Thus the deposition shows a perfect transition from clastic-dominated deltaic to pure carbonate platform settings as a result of warm climate and tectonics.This Middle Permian warming is confirmed by sea-level rise and the presence of a temperature-sensitive fusulinid fauna in association with photozoan-based ooids.Deposition of the Amb Fm.and establishment of a carbonate platform are envisaged to be associated with major rifting of northern Gondwana,which subsequently resulted in the development of a rift basin at the passive margin of the NW Indian Plate then in northern Pakistan.展开更多
The Permian is one of the most important periods during which the vegetative earth witnessed the transition from icehouse to greenhouse climate and the global environment changes.Organisms on the planet encountered gr...The Permian is one of the most important periods during which the vegetative earth witnessed the transition from icehouse to greenhouse climate and the global environment changes.Organisms on the planet encountered great challenge and the demise of swamp caused the extinction of arborescent lycopods and the rising of Mesophytic plants accomplished the floral transition from the Paleophytic to Mesophytic vegetation.In order to depict the climatic changes and floral succession in the middle and high latitudes of the North Hemisphere,palynological investigation was engaged,and 40 samples collected from the uppermost of Taerlang Formation,Hongyanchi Formation and Quanzijie Formation in the Tianshan Town,Turpan-Hami Basin,eastern Xinjiang,China.The result shows that the palynoflora in the studied area is composed of 50 species of 33 genera,dominated by disaccites and striatiti gymnosperm pollen,and characterized by diverse Protohaploxypinus,Hamia-pollenites,Alisporites and Klausipollenites.It is quite similar to those Middle and Late Permian palynological assemblages reported in the Dalongkou section and other localities in southern margin of Junggar Basin,and aged at Middle and Late Permian.The diversity of typical Angara and sub-Angara pollen,such as Falcisporites,Alisporites,Protohaploxypinus,Vittatina,Lunatisporites,Hamiapollenites,etc.indicates that the studied palynoflora belonged to the sub-Angara phytoprovince,while the presence of Lueckisporites virkkiae implied Euramerica pollen intruded northward sometimes.The paleoclimate of the studied area might be warm and humid with fluctuated dry seasons during the late Guadalupian and early Lopingian time.展开更多
Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraph...Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between the Transpecos composite sequence (chronozone)and the UAA- 1 composite sequence (chronozone).展开更多
The Permian radiolarian zones and their correlations with conodont zones or other chronostratigraphic schemes are still under debate. In this study, four genera, 21 species and two subspecies of radiolarians together ...The Permian radiolarian zones and their correlations with conodont zones or other chronostratigraphic schemes are still under debate. In this study, four genera, 21 species and two subspecies of radiolarians together with one genus and six species of conodonts were recovered from the Linghao Formation cropping out at the Longwangpo(LWP) section, northwestern Guangxi, South China. Six radiolarian interval zones and one abundance zone are recognized in the section, namely in ascending order, the Follicucullus scholasticus, Albaillella cavitata, A. protolevis, A. levis, A. excelsa, A. triangularis Interval zones and A. yaoi Abundance Zone. They are correlated with the Clarkina dukouensis, C. guangyuanensis and C. orientalis conodont zones recognized at the same section. Based on our data, the F. scholasticus Interval Zone and the lowermost part of A. cavitata Interval Zone are recognized to be upper Capitanian age, whereas the four Albaillella Interval zones are of Lopingian age(Wuchiapingian to the late Changhsingian). Two previously known Changhsingian radiolarian zones, namely the A. triangularis and A. yaoi Interval zones, should be extended down to the uppermost Wuchiapingian in this studied section.展开更多
基金supported by the SINOPEC project (G0800-06-ZS-319)the National Natural Science Foundation of China (No. 40621002)+1 种基金the Program for Changjiang Scholars and Innovative Research Team (IRT0546)the "111" Project (No. B08030)
文摘This study recovered the Guadalupian conodont faunas from Shangsi （上寺） Section in Northeast Sichuan （四川）. Four genera and nine species were identified, and three conodont zones were recognized and established; they include Jinogondolella nankingensis Zone, J. aserrata Zone, and J. postserrata Zone. The Roadian and Wordian boundary is set in the interval 5 m from the top of Bed 86 by the first appearance of the conodont J. aserrata. The Wordian and Capitanian boundary is set in the interval 2.3 m from the top of the Bed 95 by the first appearance ofJ. postserrata. Most of the specimens demonstrated low color alteration index （CAI） as 1.5-3, indicating that most part of the Maokou （茅口） Formation may have the suitable thermal conditions for the formation of oil source rocks.
文摘On the basis of establishment of radiolarian biostratigraphy and conodont biostratigraphy, a radiolarian Albaillella fauna in the transitional environment from Guadalupian to Lopingian Series in Permian was found at a pelagic chert section in southeast Guangxi, South China. Radiolarian Albaillella is one of the most sensitive biology to the transitional environment. The Albaillella fauna shows an ecological evolutionary process from Guadalupian to Lopingian: declined stage-recovery stage-flourishing stage. The study of characteristics of the Albaillella fauna in the transitional environment may provide more information, not only for the subdivision and correlation of a high-resolution biostratigraphy, but also for influence of radiolarian Albaillella fauna on the pre-Lopingian mass extinction.
基金supported by the National Natural Science Foundation of China (Nos. 40839903 and 40921062)the "111" Project (No. B08030)the Niigata University’s Scholarship Program for graduate school students conducting research abroad
文摘The Gujingling （古井岭） Section in Xiaodong （小董）, Guangxi （广西） Zhuang Autonomous Region, China, consists of cherts and siliceous siltstones, which belongs to the Bancheng （板城）Formation of the Qinzhou （钦州） allochthon. Three successive radiolarian assemblage-zones related to the Guadalupian （Middle Permian） appear in the section in the following ascending order： Pseudoalbaillella sp. aff. Pseudoaibailleila longicornis-Pseudoalbaillella fusiformis, Follicucuilus monacanthus, and Follicucuilus scholasticus-Foilicucullus porrectus. The radiolarian content in this section is generally greater than that of sponge spicules. The radiolarian fauna commonly consists of abundant Albaillellaria and spherical radiolaria with minor Latentifistularia and Entactinaria. The sponge fauna is composed mainly of hexactinellids with minor demosponges. These siliceous fossil faunal features, comparable with those in a deep basin of the western belt of the Phosphoria Basin in the western United States, indicate that the Bancheng Formation in the Gujingling Section was deposited in a basin deeper than 1 000 m. The siliceous siltstones in the section are characterized by inclusion of silt-sized quartz and no inclusion of sand-sized materials, suggesting that the Gujingling Section was located at least a few hundred kilometers from the South China Block in the Guadalupian.
基金supported by National Natural Science Foundation of China(Grant No. 40839907)
文摘The end-Paleozoic biotic crisis is characterized by two-phase mass extinctions;the first strike,resulting in a large decline of sessile benthos in shallow marine environments,occurred at the end-Guadalupian time.In order to explore the mechanism of organisms' demise,detailed analyses of depositional facies,fossil record,and carbonate carbon isotopic variations were carried out on a Maokou-Wujiaping boundary succession in northwestern Sichuan,SW China.Our data reveal a negative carbon isotopic excursion across the boundary;the gradual excursion with relatively low amplitude(2.15‰) favors a long-term influx of isotopically light 12 C sourced by the Emeishan basalt trap,rather than by rapid releasing of gas hydrate.The temporal coincidence of the beginning of accelerated negative carbon isotopic excursion with onsets of sea-level fall and massive biotic demise suggests a cause-effect link between them.Intensive volcanic activity of the Emeishan trap and sea-level fall could have resulted in detrimental environmental stresses and habitat loss for organisms,particularly for those benthic dwellers,leading to their subsequent massive extinction.
基金supported by the National Natural Science Foundation of China(NSFC Grant Nos.41272115,41572086)。
文摘A mixed siliciclastic-carbonate system that responds to changes in Permian climate and subsequent carbonate platform evolution is investigated using microscopic details of the Middle Permian Amb Formation(Fm.),in Saiyiduwali section,Khisor Range,northern Pakistan.Thin sections were made from rocks throughout the stratigraphic section of the Amb Fm.and analyzed with an emphasis on carbonate and clastic microfacies,and the latter interpreted within the existing chronostratigraphic framework.Outcrop observations reveal that the units comprise coarse-grained,channelized,ripplemarked,and burrowed sandstone and sandy,fossiliferous limestone with minor marls and shale intercalations,suggesting deposition in a subaqueous tide-dominated delta to beach barrier.Based on the determined seven microfacies coupled with outcrop observation,the Amb Fm.was deposited in a tide-influenced subaqueous delta to middle shelf environment under fluctuating sea level.The deposition of compositionally mature sandstone in the lower part of the formation suggests reworking of detritus from the rift shoulders and an adjacent source area with an ambient warm and humid climate.The stratal mixing of carbonates and compositionally mature siliciclastic units in the middle part suggest deposition under tectonic and climate-induced terrigenous and carbonate fluxes to the basin.Thus the deposition shows a perfect transition from clastic-dominated deltaic to pure carbonate platform settings as a result of warm climate and tectonics.This Middle Permian warming is confirmed by sea-level rise and the presence of a temperature-sensitive fusulinid fauna in association with photozoan-based ooids.Deposition of the Amb Fm.and establishment of a carbonate platform are envisaged to be associated with major rifting of northern Gondwana,which subsequently resulted in the development of a rift basin at the passive margin of the NW Indian Plate then in northern Pakistan.
基金Supported by National Natural Science Foundation of China(No.31670215).
文摘The Permian is one of the most important periods during which the vegetative earth witnessed the transition from icehouse to greenhouse climate and the global environment changes.Organisms on the planet encountered great challenge and the demise of swamp caused the extinction of arborescent lycopods and the rising of Mesophytic plants accomplished the floral transition from the Paleophytic to Mesophytic vegetation.In order to depict the climatic changes and floral succession in the middle and high latitudes of the North Hemisphere,palynological investigation was engaged,and 40 samples collected from the uppermost of Taerlang Formation,Hongyanchi Formation and Quanzijie Formation in the Tianshan Town,Turpan-Hami Basin,eastern Xinjiang,China.The result shows that the palynoflora in the studied area is composed of 50 species of 33 genera,dominated by disaccites and striatiti gymnosperm pollen,and characterized by diverse Protohaploxypinus,Hamia-pollenites,Alisporites and Klausipollenites.It is quite similar to those Middle and Late Permian palynological assemblages reported in the Dalongkou section and other localities in southern margin of Junggar Basin,and aged at Middle and Late Permian.The diversity of typical Angara and sub-Angara pollen,such as Falcisporites,Alisporites,Protohaploxypinus,Vittatina,Lunatisporites,Hamiapollenites,etc.indicates that the studied palynoflora belonged to the sub-Angara phytoprovince,while the presence of Lueckisporites virkkiae implied Euramerica pollen intruded northward sometimes.The paleoclimate of the studied area might be warm and humid with fluctuated dry seasons during the late Guadalupian and early Lopingian time.
文摘Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between the Transpecos composite sequence (chronozone)and the UAA- 1 composite sequence (chronozone).
基金supported by the National Natural Science Foundation of China(Grant nos.41172202,40839903 and 41372030)the Ministry of Education of China(Grant No.20110145130001)+1 种基金the 111 Project(Grant No.B08030)the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan(Grant No.MSFGPMR201502)。
文摘The Permian radiolarian zones and their correlations with conodont zones or other chronostratigraphic schemes are still under debate. In this study, four genera, 21 species and two subspecies of radiolarians together with one genus and six species of conodonts were recovered from the Linghao Formation cropping out at the Longwangpo(LWP) section, northwestern Guangxi, South China. Six radiolarian interval zones and one abundance zone are recognized in the section, namely in ascending order, the Follicucullus scholasticus, Albaillella cavitata, A. protolevis, A. levis, A. excelsa, A. triangularis Interval zones and A. yaoi Abundance Zone. They are correlated with the Clarkina dukouensis, C. guangyuanensis and C. orientalis conodont zones recognized at the same section. Based on our data, the F. scholasticus Interval Zone and the lowermost part of A. cavitata Interval Zone are recognized to be upper Capitanian age, whereas the four Albaillella Interval zones are of Lopingian age(Wuchiapingian to the late Changhsingian). Two previously known Changhsingian radiolarian zones, namely the A. triangularis and A. yaoi Interval zones, should be extended down to the uppermost Wuchiapingian in this studied section.
