Two important geological issues have a long history of debate in the Xingmeng area.The first concerns the final closure of the North China plate,Siberia plate and several intermediate massifs in the area,and the other...Two important geological issues have a long history of debate in the Xingmeng area.The first concerns the final closure of the North China plate,Siberia plate and several intermediate massifs in the area,and the other concerns the folding and lifting of the Xingmeng Trough.Disagreements arise because of issues involving the tectonicpalaeogeographical environment of the Upper Permian deposits of the Linxi Formation.The Linxi Formation(Upper Permian)is generally considered to be either an exclusively continental deposit or separated into marineterrigenous facies deposited during the Lower to Middle Linxi Period and continental deposits in the Upper Linxi Period.However,in this study,large numbers of bryozoan and sponge spicule fossils were discovered for this first time in the thick limestone layers and lenses of the upper part of the Linxi Formation found in the Guandi section of Linxi county in eastern Inner Mongolia.At the same time,abundant bryozoan fossils were also found in sedimentary tuff slices that were collected from the upper part of the Taohuayingzi Formation from the Taohuayingzi section in Ar Horqin Banner,and abundant small connecting body crinoid stem fossils were found in the dark shale of the Yangjiagou Formation from the Yangjiagou section of Jiutai county,Jilin Province.These marine fossils provide the first evidence that the Xingmeng area was still a marine or mainly marine environment at the end of the late Permian.This not only provides conclusive evidence for the recognition of the above two major geological issues but also promotes changes in the approach towards research,exploration and development of oil and gas,shale gas(oil),and other mineral resources that are preserved in the late Permian layers of the Northeast-Xingmeng area.展开更多
The Yinisala ophiolitic melange is located in the southern part of the Xiemisitai Mountains in western Junggar （NW China）, and is composed of mafic-ultra mafic rocks, siliceous blocks, marble （marbleized limestone...The Yinisala ophiolitic melange is located in the southern part of the Xiemisitai Mountains in western Junggar （NW China）, and is composed of mafic-ultra mafic rocks, siliceous blocks, marble （marbleized limestone） and pyroclastic rocks, which all crop out as faulted blocks. Rich radiolarian and sponge spicule fossils are found in the siliceous rock for the first time. There are six genera of radiolarians （including one gen. et sp. Indet.） belonging to two families： Inaniguttid gen. et sp. Indet., Inani- gutta sp., Inanibigutta sp., Inanihella bakanasensis （Nazarov）, Triplococcus acanthicus （Danelian and Popov）, Antygopora sp., which are identified to be of late Early to Middle Ordovician age, representing the upper limit of the formation age of the Yinisala ophiolite melange. The ophiolites were developed in the Early Cambrian-Middle Ordovician oceanic environment, probably an important part of the early Paleozoic Paleo-Asian Ocean, based on the composition and structure of the siliceous rock and associated deep-water fossils. The Yinisala, Taerbahatai, and Hongguleleng ophiolitic melange belts can be correlated as a suite of unified subduction accretionary complex, which extends eastward to the eastern Junggar. We consider that there existed an ancient ocean connecting the east and west of northern Junggar in the Early Cambrian-Middle Ordovician.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
基金supported by the Chinese Geological Survey(1212011120972)the National Natural Science Foundation(41072021)the Geologic Survey Project of China(1212011121067)
文摘Two important geological issues have a long history of debate in the Xingmeng area.The first concerns the final closure of the North China plate,Siberia plate and several intermediate massifs in the area,and the other concerns the folding and lifting of the Xingmeng Trough.Disagreements arise because of issues involving the tectonicpalaeogeographical environment of the Upper Permian deposits of the Linxi Formation.The Linxi Formation(Upper Permian)is generally considered to be either an exclusively continental deposit or separated into marineterrigenous facies deposited during the Lower to Middle Linxi Period and continental deposits in the Upper Linxi Period.However,in this study,large numbers of bryozoan and sponge spicule fossils were discovered for this first time in the thick limestone layers and lenses of the upper part of the Linxi Formation found in the Guandi section of Linxi county in eastern Inner Mongolia.At the same time,abundant bryozoan fossils were also found in sedimentary tuff slices that were collected from the upper part of the Taohuayingzi Formation from the Taohuayingzi section in Ar Horqin Banner,and abundant small connecting body crinoid stem fossils were found in the dark shale of the Yangjiagou Formation from the Yangjiagou section of Jiutai county,Jilin Province.These marine fossils provide the first evidence that the Xingmeng area was still a marine or mainly marine environment at the end of the late Permian.This not only provides conclusive evidence for the recognition of the above two major geological issues but also promotes changes in the approach towards research,exploration and development of oil and gas,shale gas(oil),and other mineral resources that are preserved in the late Permian layers of the Northeast-Xingmeng area.
基金supported by China Geological Survey(Grant No.1212011120502)National Natural Science Foundation of China(Grant Nos.41472001,41290260)the Special Research Fund for the Doctoral Program of Higher Education of China(Grant No.2012014-5110012)
文摘The Yinisala ophiolitic melange is located in the southern part of the Xiemisitai Mountains in western Junggar （NW China）, and is composed of mafic-ultra mafic rocks, siliceous blocks, marble （marbleized limestone） and pyroclastic rocks, which all crop out as faulted blocks. Rich radiolarian and sponge spicule fossils are found in the siliceous rock for the first time. There are six genera of radiolarians （including one gen. et sp. Indet.） belonging to two families： Inaniguttid gen. et sp. Indet., Inani- gutta sp., Inanibigutta sp., Inanihella bakanasensis （Nazarov）, Triplococcus acanthicus （Danelian and Popov）, Antygopora sp., which are identified to be of late Early to Middle Ordovician age, representing the upper limit of the formation age of the Yinisala ophiolite melange. The ophiolites were developed in the Early Cambrian-Middle Ordovician oceanic environment, probably an important part of the early Paleozoic Paleo-Asian Ocean, based on the composition and structure of the siliceous rock and associated deep-water fossils. The Yinisala, Taerbahatai, and Hongguleleng ophiolitic melange belts can be correlated as a suite of unified subduction accretionary complex, which extends eastward to the eastern Junggar. We consider that there existed an ancient ocean connecting the east and west of northern Junggar in the Early Cambrian-Middle Ordovician.
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.
