Samples were collected continuously and systematically from Beds 2 to 30 of the Meishan D section, and nearly 4,000 foraminiferal specimens were recognized. In total, 72 species （partially including undetermined spec...Samples were collected continuously and systematically from Beds 2 to 30 of the Meishan D section, and nearly 4,000 foraminiferal specimens were recognized. In total, 72 species （partially including undetermined species and conformis species） in 34 genera of foraminifers were identified. Twelve foraminiferal community zones were established from Beds 2 to 27 based on the abundance, dominance, diversity, and equitability of the foraminiferal fauna and a functional morphological analysis of the dominant and characteristic species. The habitat type indicated by each community zone and the sedimentary features were used to determine the paleo-water depths and the relative changes in sea level. We generated curves of both the habitat type and the hydrodynamic conditions, which together indicate the relative changes in the paleo-water depth and the substrate features in the studied area during the Changhsingian. This study discusses the possible relationship between the foraminiferal community zones and the sea-level changes based on a statistical analysis of the foraminiferal community zones.展开更多
On the basis of researches over several years on biostratigraphy of Changhsingian at Meishan Section D in Changxing County, the abundant materials were accumulated. This paper studies the ecostratigraphy and establis...On the basis of researches over several years on biostratigraphy of Changhsingian at Meishan Section D in Changxing County, the abundant materials were accumulated. This paper studies the ecostratigraphy and establishes 7 community zones (CZ), in ascending order, Sinoplatysomus-Geinitzina-Clarkina subcarinata, Tapashanites-Nodosaria-Clarkina subcarinata, Crurithyris-Geinitzina-Clarkina subcarinata, Glomospira-Clarkina changxingensis, Colaniella-Clarkina changxingensis, Rotodiscoceras-Palaeofusulina-Hindeodus typicalis, Clarkina meishanensis-Hypophiceras .The habitat type (HT) is different from upper shallow sea to the lower part of the lower shallow sea.展开更多
Abundant siliceous micro-fossils were found from the Dalong Formation,Xinmin section,Guizhou,which include nine species of radiolarians belonging to seven genera as well as nine types of siliceous spongy spicules.The ...Abundant siliceous micro-fossils were found from the Dalong Formation,Xinmin section,Guizhou,which include nine species of radiolarians belonging to seven genera as well as nine types of siliceous spongy spicules.The radiolarian fauna consists of all spherical radiolarians,without any species of Albaillellaria and Latentifistularia,indicating a relative shallow water sedimentary environment.The high relative co-efficient between the radiolarian abundance and total organic carbon(TOC)shows that the radiolarian assemblage represented by Copicyntra and Paracopicyntra can be used as a proxy to the paleo-productivity.However,the relative co-efficient between biogenic silica and the radiolarian and sponge spicule abundances is low.A possible explanation is that an oceanic circulation has changed the biogenic silica content after radiolarian test and siliceous spongy spicule were dissolved.展开更多
A well-preserved, abundant radiolarian fauna was obtained from three sections: the Dongpan, Liuqiao, and Paibi sections, in southern Guangxi, South China. Sixteen species belonging to Albaillella and Neoalbaillella, i...A well-preserved, abundant radiolarian fauna was obtained from three sections: the Dongpan, Liuqiao, and Paibi sections, in southern Guangxi, South China. Sixteen species belonging to Albaillella and Neoalbaillella, including seven undetermined species, are recognized. On the basis of stratigraphic distribution of these species, two radiolarian zones, the Albaillella triangularis Zone and the Albaillella yaoi Zone, are established. The correlation between radiolarian zones and conodont zones is suggested based on the discovery of coexisting conodonts. Albaillella triangularis and Albaillella yaoi zones correspond to Neogondolella postwangi and Neogondolella yini zones respectively.展开更多
Sedimentary environment and distribution of brachiopods during the Changhsingian in Xingwen, Si-chuan Province of the upper Yangtze region, are statistically analyzed. Changing regularity in diversity of brachiopod is...Sedimentary environment and distribution of brachiopods during the Changhsingian in Xingwen, Si-chuan Province of the upper Yangtze region, are statistically analyzed. Changing regularity in diversity of brachiopod is synthetically investigated based on qualitative and quantitative analysis of transgres-sion-regression cycles. The results show that the diversity of brachiopods in this region in the trans-gression (aggradation) sequence is higher than that in the regression (progradation) sequence. The brachiopods in this area began to diversify in the early Changhsingian. And the species diversity had four peak stages which are respectively in the middle Early Changhsingian, late Early Changhsingian, early Late Changhsingian and late Late Changhsingian. The species diversity reached its highest in the late Late Changhsingian but this is followed by a sharp decrease at the end-hanghsingian, indicating the mass extinction of most brachiopod species which were prosperous in the Late Paleozoic.展开更多
The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic m...The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic matter(OM)enrichment throughout this period is still controversial.Based on geochemical data,the marine redox conditions,paleogeographic and hydrographic environment,primary productivity,volcanism,and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section,Chaohu,to provide new insights into OM accumulation.Five Phases are distinguished based on the TOC and environmental variations.In Phase I,anoxic conditions driven by water restriction enhanced OM preservation.In Phase II,euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition.During Phase III,intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition.Phase IV was characterized by a relatively higher abundance of mercury(Hg)and TOC(peak at 16.98 wt%),indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment.In Phase V,extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity.Phases I,II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors,namely paleogeographic,hydrographic environment,volcanism,and redox conditions.展开更多
基金supported by the Foundation of the Geological Survey of China [grant no. 121201004000150021]
文摘Samples were collected continuously and systematically from Beds 2 to 30 of the Meishan D section, and nearly 4,000 foraminiferal specimens were recognized. In total, 72 species （partially including undetermined species and conformis species） in 34 genera of foraminifers were identified. Twelve foraminiferal community zones were established from Beds 2 to 27 based on the abundance, dominance, diversity, and equitability of the foraminiferal fauna and a functional morphological analysis of the dominant and characteristic species. The habitat type indicated by each community zone and the sedimentary features were used to determine the paleo-water depths and the relative changes in sea level. We generated curves of both the habitat type and the hydrodynamic conditions, which together indicate the relative changes in the paleo-water depth and the substrate features in the studied area during the Changhsingian. This study discusses the possible relationship between the foraminiferal community zones and the sea-level changes based on a statistical analysis of the foraminiferal community zones.
文摘On the basis of researches over several years on biostratigraphy of Changhsingian at Meishan Section D in Changxing County, the abundant materials were accumulated. This paper studies the ecostratigraphy and establishes 7 community zones (CZ), in ascending order, Sinoplatysomus-Geinitzina-Clarkina subcarinata, Tapashanites-Nodosaria-Clarkina subcarinata, Crurithyris-Geinitzina-Clarkina subcarinata, Glomospira-Clarkina changxingensis, Colaniella-Clarkina changxingensis, Rotodiscoceras-Palaeofusulina-Hindeodus typicalis, Clarkina meishanensis-Hypophiceras .The habitat type (HT) is different from upper shallow sea to the lower part of the lower shallow sea.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40839903,40921062)special funding from the GPMR
文摘Abundant siliceous micro-fossils were found from the Dalong Formation,Xinmin section,Guizhou,which include nine species of radiolarians belonging to seven genera as well as nine types of siliceous spongy spicules.The radiolarian fauna consists of all spherical radiolarians,without any species of Albaillellaria and Latentifistularia,indicating a relative shallow water sedimentary environment.The high relative co-efficient between the radiolarian abundance and total organic carbon(TOC)shows that the radiolarian assemblage represented by Copicyntra and Paracopicyntra can be used as a proxy to the paleo-productivity.However,the relative co-efficient between biogenic silica and the radiolarian and sponge spicule abundances is low.A possible explanation is that an oceanic circulation has changed the biogenic silica content after radiolarian test and siliceous spongy spicule were dissolved.
基金NSFC Inovation Research Group Programm (Grant No. 40621002)MOE Innovative Research Team Progam (Grant No. IRT0546)+1 种基金"111" Project (Grant No. B08030)the SINOPEC Project (Grant No. G0800-06-ZS-319)
文摘A well-preserved, abundant radiolarian fauna was obtained from three sections: the Dongpan, Liuqiao, and Paibi sections, in southern Guangxi, South China. Sixteen species belonging to Albaillella and Neoalbaillella, including seven undetermined species, are recognized. On the basis of stratigraphic distribution of these species, two radiolarian zones, the Albaillella triangularis Zone and the Albaillella yaoi Zone, are established. The correlation between radiolarian zones and conodont zones is suggested based on the discovery of coexisting conodonts. Albaillella triangularis and Albaillella yaoi zones correspond to Neogondolella postwangi and Neogondolella yini zones respectively.
基金the National Natural Science Foundation of China (Grant No. 40272016) the State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology,CAS (Grant No.043105)
文摘Sedimentary environment and distribution of brachiopods during the Changhsingian in Xingwen, Si-chuan Province of the upper Yangtze region, are statistically analyzed. Changing regularity in diversity of brachiopod is synthetically investigated based on qualitative and quantitative analysis of transgres-sion-regression cycles. The results show that the diversity of brachiopods in this region in the trans-gression (aggradation) sequence is higher than that in the regression (progradation) sequence. The brachiopods in this area began to diversify in the early Changhsingian. And the species diversity had four peak stages which are respectively in the middle Early Changhsingian, late Early Changhsingian, early Late Changhsingian and late Late Changhsingian. The species diversity reached its highest in the late Late Changhsingian but this is followed by a sharp decrease at the end-hanghsingian, indicating the mass extinction of most brachiopod species which were prosperous in the Late Paleozoic.
基金supported by the Fundamental and Commonwealth Geological Survey of Oil and Gas of China(Grant No.DD 20221662)the National Natural Science Foundation of China(NSFC)Program(Grant No.42302124).
文摘The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic matter(OM)enrichment throughout this period is still controversial.Based on geochemical data,the marine redox conditions,paleogeographic and hydrographic environment,primary productivity,volcanism,and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section,Chaohu,to provide new insights into OM accumulation.Five Phases are distinguished based on the TOC and environmental variations.In Phase I,anoxic conditions driven by water restriction enhanced OM preservation.In Phase II,euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition.During Phase III,intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition.Phase IV was characterized by a relatively higher abundance of mercury(Hg)and TOC(peak at 16.98 wt%),indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment.In Phase V,extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity.Phases I,II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors,namely paleogeographic,hydrographic environment,volcanism,and redox conditions.
