Objective The Simao Basin in Yunnan Province has developed Cretaceous evaporite-bearing clastic deposits, including the Mangang and Mengyejing Formations which were originally interpreted as fluvial and lacustrine dep...Objective The Simao Basin in Yunnan Province has developed Cretaceous evaporite-bearing clastic deposits, including the Mangang and Mengyejing Formations which were originally interpreted as fluvial and lacustrine deposits. The Mangang Fm. composed of well-rounded quartz sandstones, were commonly considered as the bottom part of the Mengyejing salt series. Dttring last decades,展开更多
The Qiangtang Basin of Tibetan Plateau most widely outcrops marine Jurassic strata in China,even in eastern Asian,and the Jurassic strata and ammonites’occurrence are in favor of researching evolution of paleoceanogr...The Qiangtang Basin of Tibetan Plateau most widely outcrops marine Jurassic strata in China,even in eastern Asian,and the Jurassic strata and ammonites’occurrence are in favor of researching evolution of paleoceanography in the Tethyan region and global stratigraphic comparison.This work focused on the carbon isotope changes across the J I–J 2 boundary in the eastern Tethys region.展开更多
Objective The organic-matter-rich oil shales outcropped at the Biluo Co area of the Qiangtang Basin in Tibet are of the Toarcian(Early Jurassic)based on the ammonite fauna(Yi et al.,2003).We first proposed its sedimen...Objective The organic-matter-rich oil shales outcropped at the Biluo Co area of the Qiangtang Basin in Tibet are of the Toarcian(Early Jurassic)based on the ammonite fauna(Yi et al.,2003).We first proposed its sedimentary age to be the Early Toarcian and correlated with the Posidonia shales and the early Toarcian Oceanic Anoxic Event(TOAE)(Chen et al.,2005).The carbon isotopes excursions and Buchi bivalves suggest that these oil shales at the Biluo Co section are represent of T-OAE in the Asian Tethyan regions.展开更多
Objective The East Kunlun Orogenic belt constitutes the first marked change in the topographic reliefs north of the Qinghai-Tibet Plateau.The Cenozoic tectonic evolution of this orogenic belt is crucial for understand...Objective The East Kunlun Orogenic belt constitutes the first marked change in the topographic reliefs north of the Qinghai-Tibet Plateau.The Cenozoic tectonic evolution of this orogenic belt is crucial for understanding the remote deformational effects of the Eurasian plate collision and the migration track at the northern margin of the plateau.However,when and how the uplift occurred remains展开更多
As a special sedimentary grain type, the coated grain(with an ooid model) has been known for two centuries due to its fascinating special fabric and genesis developments. The leading factors in forming the coated grai...As a special sedimentary grain type, the coated grain(with an ooid model) has been known for two centuries due to its fascinating special fabric and genesis developments. The leading factors in forming the coated grain consist mainly of:(1) microorganism movement field;(2) chemical sedimentary effect;(3) hydrodynamic force environment and topography condition;(4) abundant core material supply;(5) embedding condition; and(6) humic acids condition in water medium. With the development of the coated grain genesis, the single factor theory cannot reasonably explain the exact formation of the surface sediment of coated grain. Here, we find a new way to study the coated grain on the basis of traditional research methods. The Wenquan area on the northeast edge of the Qiangtang Basin is one of the few areas where the coated grain is developing, and is a rare "natural laboratory" for the study of the coated grain and the thermal spring sediment. The oolitic sinter of the area has the triaxiality modality of pea polymer, and is obviously different from the karst travertine and the normal lacustrine ooid. We found that the hot spring water in the Wenquan area has higher partial pressure of CO2(PCO2) and saturation index of the calcite(SIc) than normal. Macrocosmically, the oolitic sinter is shaped like a pea, and its grains and gap fillings are light yellow. Microcosmically, the sinter grain forms six types of fundamental lamina, and those six types are developed to be four grain types with different combinations. The C-axis of the mineral grain of sinter cement(calcite) is normal to the lamina face, and grows on it with distinct generation formations. In short, the grain type of oolitic sinter is the oncoid, with the grain development caused by the factors such as the shallow water of strong hydrodynamic force, the special hydrochemistry condition, and the extensive algae activities(diatom).展开更多
基金supported by the Chinese National Key Project for Basic Research(grant No. 2011CB403007)the National Natural Science Foundation of China(grant No.41602127)
文摘Objective The Simao Basin in Yunnan Province has developed Cretaceous evaporite-bearing clastic deposits, including the Mangang and Mengyejing Formations which were originally interpreted as fluvial and lacustrine deposits. The Mangang Fm. composed of well-rounded quartz sandstones, were commonly considered as the bottom part of the Mengyejing salt series. Dttring last decades,
基金supported by the National Natural Science Foundation of China(grants No.41572089 and 41572095)
文摘The Qiangtang Basin of Tibetan Plateau most widely outcrops marine Jurassic strata in China,even in eastern Asian,and the Jurassic strata and ammonites’occurrence are in favor of researching evolution of paleoceanography in the Tethyan region and global stratigraphic comparison.This work focused on the carbon isotope changes across the J I–J 2 boundary in the eastern Tethys region.
基金supported by the National Natural Science Foundation of China (grants No. 41572089, 41572095 and 41602122)
文摘Objective The organic-matter-rich oil shales outcropped at the Biluo Co area of the Qiangtang Basin in Tibet are of the Toarcian(Early Jurassic)based on the ammonite fauna(Yi et al.,2003).We first proposed its sedimentary age to be the Early Toarcian and correlated with the Posidonia shales and the early Toarcian Oceanic Anoxic Event(TOAE)(Chen et al.,2005).The carbon isotopes excursions and Buchi bivalves suggest that these oil shales at the Biluo Co section are represent of T-OAE in the Asian Tethyan regions.
基金financially supported by the National Natural Science Foundation of China (grants No. 41402099 and No. 40972084)
文摘Objective The East Kunlun Orogenic belt constitutes the first marked change in the topographic reliefs north of the Qinghai-Tibet Plateau.The Cenozoic tectonic evolution of this orogenic belt is crucial for understanding the remote deformational effects of the Eurasian plate collision and the migration track at the northern margin of the plateau.However,when and how the uplift occurred remains
基金supported by the National Natural Science Foundation of China (Grant Nos. 40972084 and 41102060)
文摘As a special sedimentary grain type, the coated grain(with an ooid model) has been known for two centuries due to its fascinating special fabric and genesis developments. The leading factors in forming the coated grain consist mainly of:(1) microorganism movement field;(2) chemical sedimentary effect;(3) hydrodynamic force environment and topography condition;(4) abundant core material supply;(5) embedding condition; and(6) humic acids condition in water medium. With the development of the coated grain genesis, the single factor theory cannot reasonably explain the exact formation of the surface sediment of coated grain. Here, we find a new way to study the coated grain on the basis of traditional research methods. The Wenquan area on the northeast edge of the Qiangtang Basin is one of the few areas where the coated grain is developing, and is a rare "natural laboratory" for the study of the coated grain and the thermal spring sediment. The oolitic sinter of the area has the triaxiality modality of pea polymer, and is obviously different from the karst travertine and the normal lacustrine ooid. We found that the hot spring water in the Wenquan area has higher partial pressure of CO2(PCO2) and saturation index of the calcite(SIc) than normal. Macrocosmically, the oolitic sinter is shaped like a pea, and its grains and gap fillings are light yellow. Microcosmically, the sinter grain forms six types of fundamental lamina, and those six types are developed to be four grain types with different combinations. The C-axis of the mineral grain of sinter cement(calcite) is normal to the lamina face, and grows on it with distinct generation formations. In short, the grain type of oolitic sinter is the oncoid, with the grain development caused by the factors such as the shallow water of strong hydrodynamic force, the special hydrochemistry condition, and the extensive algae activities(diatom).
