The Lower Ordovician Tongzi Formation containing abundant shoal sediments is the most promising stratum for the petroleum exploration in the Sichuan Basin.However,the current studies mainly focus on the central part o...The Lower Ordovician Tongzi Formation containing abundant shoal sediments is the most promising stratum for the petroleum exploration in the Sichuan Basin.However,the current studies mainly focus on the central part of the Basin,the systematic analysis of the southeastern part with well-developed shoal facies is lacking.This paper aims to clarify the characteristics and genesis of the Tongzi Formation reservoir in Southeastern Sichuan Basin,following an analysis of sedimentary facies within the sequence stratigraphic framework.The research shows that the main types of reservoir rocks are oolitic,intraclastic and bioclastic dolostones.And the reservoir spaces consist mainly of intergranular(dissolved)pores,intercrystalline(dissolved)pores,intragranular dissolved pores and fractures.Among them,intergranular pores account for the highest proportion,which is followed by intragranular dissolved pores.In addition,most throats are necking and flaky which mainly connect intergranular and intercrystalline pores,respectively.The diagenetic sequence shows that penecontemporaneous karst well improved the porosity of the reservoir in the early-stage although the cementation and compaction reduced parts of pores.The reservoir formation is associated with the tectonic-depositional settings,diageneses and terrigenous contamination.Paleohighlands and submerged uplifts,forming in the early Ordovician amalgamation between Yangtze and Cathaysia blocks,accumulated shoal sediments as the material basis for the reservoir formation.Penecontemporaneous karst forming intragranular dissolved pores and the dolomitization aiding grainstones to resist the pressure solution are the key to increasing porosity and preserving pores.The absence of terrigenous contamination prevented intergranular pores from being strongly cemented,which resulted in the reservoir difference between the central and southeastern Sichuan Basin.The study can be used as a reference for the further exploration of Ordovician petroleum in the Sichuan Basin and other regions owning similar geological settings.展开更多
The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is inco...The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is incomplete,and phylogenetic relationships within the order Nymphaeales remain controversial.In this study,12 chloroplast genomes of Nymphaea were assembled and analyzed for the first time.These genomes were 158,290-160,042 bp in size and contained 113 non-repeat genes,including 79 protein-coding genes,30 tRNA genes,and four rRNA genes.We also report on codon usage,RNA editing sites,microsatellite structures,and new repetitive sequences in this genus.Comparative genomics revealed that expansion and contraction of IR regions can lead to changes in the gene numbers.Additionally,it was observed that the highly variable regions of the chloroplast genome were mainly located in intergenic regions.Furthermore,the phylogenetic tree showed the order Nymphaeales was divided into three families,and the genus Nymphaea can be divided into five(or three)subgenera,with the subgenus Nymphaea being the oldest.The divergence times of nymphaealean taxa were analyzed,with origins of the order Nymphaeales and family Nymphaeaceae being about 194 and 131 million years,respectively.The results of the phylo-genetic analysis and estimated divergence times will be useful for future evolutionary studies of basal angiosperm lineages.展开更多
基金research was funded by National Natural Science Founda-tion of China(42102190,42102193,and U19B6003)CNPC Up-stream Field Fundamental Forward-looking Projects:Research on Reconstruction Technology of Remaining Marine Basin Tectonic-Lithofacies Paleogeography(No.2021DJ0501)。
文摘The Lower Ordovician Tongzi Formation containing abundant shoal sediments is the most promising stratum for the petroleum exploration in the Sichuan Basin.However,the current studies mainly focus on the central part of the Basin,the systematic analysis of the southeastern part with well-developed shoal facies is lacking.This paper aims to clarify the characteristics and genesis of the Tongzi Formation reservoir in Southeastern Sichuan Basin,following an analysis of sedimentary facies within the sequence stratigraphic framework.The research shows that the main types of reservoir rocks are oolitic,intraclastic and bioclastic dolostones.And the reservoir spaces consist mainly of intergranular(dissolved)pores,intercrystalline(dissolved)pores,intragranular dissolved pores and fractures.Among them,intergranular pores account for the highest proportion,which is followed by intragranular dissolved pores.In addition,most throats are necking and flaky which mainly connect intergranular and intercrystalline pores,respectively.The diagenetic sequence shows that penecontemporaneous karst well improved the porosity of the reservoir in the early-stage although the cementation and compaction reduced parts of pores.The reservoir formation is associated with the tectonic-depositional settings,diageneses and terrigenous contamination.Paleohighlands and submerged uplifts,forming in the early Ordovician amalgamation between Yangtze and Cathaysia blocks,accumulated shoal sediments as the material basis for the reservoir formation.Penecontemporaneous karst forming intragranular dissolved pores and the dolomitization aiding grainstones to resist the pressure solution are the key to increasing porosity and preserving pores.The absence of terrigenous contamination prevented intergranular pores from being strongly cemented,which resulted in the reservoir difference between the central and southeastern Sichuan Basin.The study can be used as a reference for the further exploration of Ordovician petroleum in the Sichuan Basin and other regions owning similar geological settings.
基金supported by the National Natural Science Foundation of China(No.32370244)the Taishan Scholar Project(No.tsqn202306214)+1 种基金the Shandong Province Natural Science Foundation of China(No.ZR2023MC157)the State Key Laboratory of Pal-aeobiology and Stratigraphy(No.223123).
文摘The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is incomplete,and phylogenetic relationships within the order Nymphaeales remain controversial.In this study,12 chloroplast genomes of Nymphaea were assembled and analyzed for the first time.These genomes were 158,290-160,042 bp in size and contained 113 non-repeat genes,including 79 protein-coding genes,30 tRNA genes,and four rRNA genes.We also report on codon usage,RNA editing sites,microsatellite structures,and new repetitive sequences in this genus.Comparative genomics revealed that expansion and contraction of IR regions can lead to changes in the gene numbers.Additionally,it was observed that the highly variable regions of the chloroplast genome were mainly located in intergenic regions.Furthermore,the phylogenetic tree showed the order Nymphaeales was divided into three families,and the genus Nymphaea can be divided into five(or three)subgenera,with the subgenus Nymphaea being the oldest.The divergence times of nymphaealean taxa were analyzed,with origins of the order Nymphaeales and family Nymphaeaceae being about 194 and 131 million years,respectively.The results of the phylo-genetic analysis and estimated divergence times will be useful for future evolutionary studies of basal angiosperm lineages.
