The Mesoproterozoic Wumishan Formation at the Jixian section in Tianjin is a set of more than 3000-m-thick stromatolitic carbonate succession.In this succession,several lithofacies units,that is,the subtidal stromatol...The Mesoproterozoic Wumishan Formation at the Jixian section in Tianjin is a set of more than 3000-m-thick stromatolitic carbonate succession.In this succession,several lithofacies units,that is,the subtidal stromatolitic biostrome,the thrombolitic bioherm,tidal-flat micritic dolomite and lagoon dolomitic shale,make up many meter-scale cycles of the peritidal carbonate type that have been nominated as the Wumishan cycles.Importantly,many microdigital stromatolites make up the stromatolitic biostrome unit of the Wumishan cycles in the lower part of the Wumishan Formation. These microdigital stromatolites have been grouped as a stromatolitic assemblage by paleontologists, that is,＂Pseudogymnosolen mopanyuensis-Scuphus-Yangzhuang columnaris＂assemblage.These microdigital stromatolites had also been interpreted as the aragonite（tufa） sea-floor precipitates by sedimentologists,and has further been thought as the special products of the transitional period from the sea-floor aragonite precipitates of the Archean to the clastic and muddy carbonates of the Neoproterozoic.Although there are some restrictions for the stratigraphic meaning of the concept of the stromatolitic assemblage,detailed studies on classification by paleontologists provide an important clue to understand the sedimentological meaning of the microdigital stromatolites.Furthermore,an important and obvious horizon for the end of the microdigital stromatolites was recorded in the Mesoproterozoic Wumishan Formation at the Jixian section,which provides useful information to understand the stromatolite decline occurred at c.1250 Ma and the evolving carbonate world of the Precambrian.展开更多
1 Introduction Chabocuo Lake is located in the territory of Gaize County Ali area Tibet,the altitude of the lake-surface is4505 m with a total area of 32 Km2.It is a typical sulfate type saline and rich in boron and l...1 Introduction Chabocuo Lake is located in the territory of Gaize County Ali area Tibet,the altitude of the lake-surface is4505 m with a total area of 32 Km2.It is a typical sulfate type saline and rich in boron and lithium.In the natural evaporation process,several mineral sylvites cocrystallize out,thus increases the difficulties for separating and展开更多
EDITOR’S NOTE: Yuan Imperial Tutor Kongge Norgu Norsgyansang was the great grandson of Pagba,In 1319, he issued a written order to the Bodongye.The order called on lamas in areas subject to Bodongye rule to refrain f...EDITOR’S NOTE: Yuan Imperial Tutor Kongge Norgu Norsgyansang was the great grandson of Pagba,In 1319, he issued a written order to the Bodongye.The order called on lamas in areas subject to Bodongye rule to refrain from levying more taxes on the populace, putting up tents outside monasteries,and bullying the people.展开更多
基金part of the project"Study on Cycles and Events and Their Relative Sedimentological Problems for the Mesoproterozoic Jixian System in the Yanshan Region"(Grant No.40472065)financially supported by the National Natural Sciences Foundation of China+1 种基金is part of the project"Study on Lithofacies and Paleogeography from Meso- to Neoproterozoic in North China"financially supported by the China Petrochemical Corporation(Grant No.C0800-07-ZS- 164).
文摘The Mesoproterozoic Wumishan Formation at the Jixian section in Tianjin is a set of more than 3000-m-thick stromatolitic carbonate succession.In this succession,several lithofacies units,that is,the subtidal stromatolitic biostrome,the thrombolitic bioherm,tidal-flat micritic dolomite and lagoon dolomitic shale,make up many meter-scale cycles of the peritidal carbonate type that have been nominated as the Wumishan cycles.Importantly,many microdigital stromatolites make up the stromatolitic biostrome unit of the Wumishan cycles in the lower part of the Wumishan Formation. These microdigital stromatolites have been grouped as a stromatolitic assemblage by paleontologists, that is,＂Pseudogymnosolen mopanyuensis-Scuphus-Yangzhuang columnaris＂assemblage.These microdigital stromatolites had also been interpreted as the aragonite（tufa） sea-floor precipitates by sedimentologists,and has further been thought as the special products of the transitional period from the sea-floor aragonite precipitates of the Archean to the clastic and muddy carbonates of the Neoproterozoic.Although there are some restrictions for the stratigraphic meaning of the concept of the stromatolitic assemblage,detailed studies on classification by paleontologists provide an important clue to understand the sedimentological meaning of the microdigital stromatolites.Furthermore,an important and obvious horizon for the end of the microdigital stromatolites was recorded in the Mesoproterozoic Wumishan Formation at the Jixian section,which provides useful information to understand the stromatolite decline occurred at c.1250 Ma and the evolving carbonate world of the Precambrian.
文摘1 Introduction Chabocuo Lake is located in the territory of Gaize County Ali area Tibet,the altitude of the lake-surface is4505 m with a total area of 32 Km2.It is a typical sulfate type saline and rich in boron and lithium.In the natural evaporation process,several mineral sylvites cocrystallize out,thus increases the difficulties for separating and
文摘EDITOR’S NOTE: Yuan Imperial Tutor Kongge Norgu Norsgyansang was the great grandson of Pagba,In 1319, he issued a written order to the Bodongye.The order called on lamas in areas subject to Bodongye rule to refrain from levying more taxes on the populace, putting up tents outside monasteries,and bullying the people.
