The Bancheng Formation exposed along the Shift Reservoir nearby Bancheng Town, Qinfang Basin, southern Guangxi, is mainly composed of thin-bedded chert. The radiolarian assemblages in the studied section suggest it wa...The Bancheng Formation exposed along the Shift Reservoir nearby Bancheng Town, Qinfang Basin, southern Guangxi, is mainly composed of thin-bedded chert. The radiolarian assemblages in the studied section suggest it was a pelagic setting and the age of the Bancheng Formation is Late Carboniferous to Early Permian. The detrital zircon U-Pb ages from the section are characterized by a Permian peak at -282 Ma. Detrital zircon provenance analysis suggests that the Permian detrital zircons in the Bancheng Formation were likely from volcanic-magmatic arc rocks related to the subducfton of the Paleo-Tethyan Ocean. The long-lived deposition （from Upper Devonian to Middle Permian, about 125 Ma） of the radiolarian cherts in the Qinfang Basin was comparable with that deposited in Ailaoshan Ocean. The radiolarian assemblages in Qinfang Basin show a Tethyan affinity. Together with the Permian subduction-related arc volcanic rocks and the E-MORB type basalts to the northwest of the study area, our data support the existence of a Permian arc-related basin in the Qinfang area.展开更多
The Gujingling （古井岭） Section in Xiaodong （小董）, Guangxi （广西） Zhuang Autonomous Region, China, consists of cherts and siliceous siltstones, which belongs to the Bancheng （板城）Formation of the Qinzhou （...The Gujingling （古井岭） Section in Xiaodong （小董）, Guangxi （广西） Zhuang Autonomous Region, China, consists of cherts and siliceous siltstones, which belongs to the Bancheng （板城）Formation of the Qinzhou （钦州） allochthon. Three successive radiolarian assemblage-zones related to the Guadalupian （Middle Permian） appear in the section in the following ascending order： Pseudoalbaillella sp. aff. Pseudoaibailleila longicornis-Pseudoalbaillella fusiformis, Follicucuilus monacanthus, and Follicucuilus scholasticus-Foilicucullus porrectus. The radiolarian content in this section is generally greater than that of sponge spicules. The radiolarian fauna commonly consists of abundant Albaillellaria and spherical radiolaria with minor Latentifistularia and Entactinaria. The sponge fauna is composed mainly of hexactinellids with minor demosponges. These siliceous fossil faunal features, comparable with those in a deep basin of the western belt of the Phosphoria Basin in the western United States, indicate that the Bancheng Formation in the Gujingling Section was deposited in a basin deeper than 1 000 m. The siliceous siltstones in the section are characterized by inclusion of silt-sized quartz and no inclusion of sand-sized materials, suggesting that the Gujingling Section was located at least a few hundred kilometers from the South China Block in the Guadalupian.展开更多
基金supported by the National Natural Science Foundation of China(No.41772016)the China Geological Survey(Nos.1212011220529,121201004000150021,and 121201017000172004)the Key Research and Development Project of the Ministry of Science and Technology(No.2016YFC0601005)
文摘The Bancheng Formation exposed along the Shift Reservoir nearby Bancheng Town, Qinfang Basin, southern Guangxi, is mainly composed of thin-bedded chert. The radiolarian assemblages in the studied section suggest it was a pelagic setting and the age of the Bancheng Formation is Late Carboniferous to Early Permian. The detrital zircon U-Pb ages from the section are characterized by a Permian peak at -282 Ma. Detrital zircon provenance analysis suggests that the Permian detrital zircons in the Bancheng Formation were likely from volcanic-magmatic arc rocks related to the subducfton of the Paleo-Tethyan Ocean. The long-lived deposition （from Upper Devonian to Middle Permian, about 125 Ma） of the radiolarian cherts in the Qinfang Basin was comparable with that deposited in Ailaoshan Ocean. The radiolarian assemblages in Qinfang Basin show a Tethyan affinity. Together with the Permian subduction-related arc volcanic rocks and the E-MORB type basalts to the northwest of the study area, our data support the existence of a Permian arc-related basin in the Qinfang area.
基金supported by the National Natural Science Foundation of China (Nos. 40839903 and 40921062)the "111" Project (No. B08030)the Niigata University’s Scholarship Program for graduate school students conducting research abroad
文摘The Gujingling （古井岭） Section in Xiaodong （小董）, Guangxi （广西） Zhuang Autonomous Region, China, consists of cherts and siliceous siltstones, which belongs to the Bancheng （板城）Formation of the Qinzhou （钦州） allochthon. Three successive radiolarian assemblage-zones related to the Guadalupian （Middle Permian） appear in the section in the following ascending order： Pseudoalbaillella sp. aff. Pseudoaibailleila longicornis-Pseudoalbaillella fusiformis, Follicucuilus monacanthus, and Follicucuilus scholasticus-Foilicucullus porrectus. The radiolarian content in this section is generally greater than that of sponge spicules. The radiolarian fauna commonly consists of abundant Albaillellaria and spherical radiolaria with minor Latentifistularia and Entactinaria. The sponge fauna is composed mainly of hexactinellids with minor demosponges. These siliceous fossil faunal features, comparable with those in a deep basin of the western belt of the Phosphoria Basin in the western United States, indicate that the Bancheng Formation in the Gujingling Section was deposited in a basin deeper than 1 000 m. The siliceous siltstones in the section are characterized by inclusion of silt-sized quartz and no inclusion of sand-sized materials, suggesting that the Gujingling Section was located at least a few hundred kilometers from the South China Block in the Guadalupian.
