Sediments of carbonate gravity flows and terrigenous debris turbidites, and normal bathyal deposits were found at the Shaiwa Section, Ziyun County, Guizhou Province, southwestern China. Through grain size analysis of...Sediments of carbonate gravity flows and terrigenous debris turbidites, and normal bathyal deposits were found at the Shaiwa Section, Ziyun County, Guizhou Province, southwestern China. Through grain size analysis of some typical sediments at this section, the changing patterns of the grain parameters and the grain size cumulations were recovered. Results show that the study area was deposited under turbidite control during the Late Permian period, which we also recognized at the outcrop section upon sedimentary characteristics of the sediments. In addition, fossils are abundant in the Upper Permian of the Shaiwa Section, including radiolarians, sponge spicules, bivalves, brachiopods, ammonoids and trace fossils. Radiolarians and siliceous sponge spicules are typical deep water assemblages. Bivalves are dominated by genera of Hunanopecten and Claraia , both showing deep water living characteristics. Ammonoids are composed of planktonic types, showing characteristics of smooth and flat shells. Brachiopods are dominated by a small and thin shelled assemblage, which are commonly flat in shape and usually of slight ornamentations on shells. In addition, trace fossils found at the Shaiwa Section are also common types of deep water facies. Thus, the fossil evidence of the Shaiwa Section also suggests a deep water environment, possibly from the bathyal slope to the basin margin facies, of the studied area during the Late Permian period.展开更多
The Nanpanjiang Basin is a key area for paleontological and biostratigraphical study of the Middle Triassic.Herein we studied Middle Triassic conodonts from a well-exposed section,the Shaiwa Section,which is located a...The Nanpanjiang Basin is a key area for paleontological and biostratigraphical study of the Middle Triassic.Herein we studied Middle Triassic conodonts from a well-exposed section,the Shaiwa Section,which is located at the northwest end of the Nanpanjiang Basin.A total of six Anisian conodont zones are recognized;in ascending order,they are:the Nicoraella germanica Zone,the Nicoraella kockeli Zone,the Paragondolella bulgarica Zone,the Neogondolella constricta Zone,the Neogondolella cornuta Zone,and the Paragondolella excelsa Zone,respectively.The first occurrence of Nicoraella kockeli defines the Bithynian-Pelsonian boundary.The Pelsonian-Illyrian boundary is defined by the first occurrence of Neogondolella constricta.The Anisian-Ladinian boundary cannot be recognized at the Shaiwa Section due to the absence of conodont indicative of the Ladinian.However,the new conodont data indicate that the uppermost strata could be very close to the boundary.The abrasion of conodont surfaces provides evidence for demonstrating reworking at the Shaiwa Section,which makes some conodonts possess a longer stratigraphic range than previously recorded.The variation in relative abundance between blade-shaped conodonts and platform conodonts indicates that segminiplanate elements probably preferred deeper and oxygenated environments whereas a restricted marine environment is more suitable for segminate elements.展开更多
顶苏地区晒瓦组以灰色、深灰色薄—中厚层泥质岩屑粉砂岩为主,基本层序由细砂岩—粉砂岩—粘土岩组成,向上粒径变细,层理变薄。在顶苏—小革么—带晒瓦组底发育砾岩层,为晚二叠世沿中二叠统侵蚀面上发育的一套河流相碎屑岩沉积。砾岩层...顶苏地区晒瓦组以灰色、深灰色薄—中厚层泥质岩屑粉砂岩为主,基本层序由细砂岩—粉砂岩—粘土岩组成,向上粒径变细,层理变薄。在顶苏—小革么—带晒瓦组底发育砾岩层,为晚二叠世沿中二叠统侵蚀面上发育的一套河流相碎屑岩沉积。砾岩层之下灰岩中产牙形石Neogondolella granti Barskov et koroleva,同时根据晒瓦组假整合于峨眉山玄武岩之上,因此晒瓦组为晚二叠世产物。展开更多
基金the National Natural Science Foundationof China ( Nos. 40172012 and 40232025 ), the Australian Common wealth Government and Deakin University for the award of an Interna tional Postgraduate Research Scholarship (IPRS) to PYQ
文摘Sediments of carbonate gravity flows and terrigenous debris turbidites, and normal bathyal deposits were found at the Shaiwa Section, Ziyun County, Guizhou Province, southwestern China. Through grain size analysis of some typical sediments at this section, the changing patterns of the grain parameters and the grain size cumulations were recovered. Results show that the study area was deposited under turbidite control during the Late Permian period, which we also recognized at the outcrop section upon sedimentary characteristics of the sediments. In addition, fossils are abundant in the Upper Permian of the Shaiwa Section, including radiolarians, sponge spicules, bivalves, brachiopods, ammonoids and trace fossils. Radiolarians and siliceous sponge spicules are typical deep water assemblages. Bivalves are dominated by genera of Hunanopecten and Claraia , both showing deep water living characteristics. Ammonoids are composed of planktonic types, showing characteristics of smooth and flat shells. Brachiopods are dominated by a small and thin shelled assemblage, which are commonly flat in shape and usually of slight ornamentations on shells. In addition, trace fossils found at the Shaiwa Section are also common types of deep water facies. Thus, the fossil evidence of the Shaiwa Section also suggests a deep water environment, possibly from the bathyal slope to the basin margin facies, of the studied area during the Late Permian period.
基金funded by the National Natural Science Foundation of China(Nos.41972033,41830320,41572324)。
文摘The Nanpanjiang Basin is a key area for paleontological and biostratigraphical study of the Middle Triassic.Herein we studied Middle Triassic conodonts from a well-exposed section,the Shaiwa Section,which is located at the northwest end of the Nanpanjiang Basin.A total of six Anisian conodont zones are recognized;in ascending order,they are:the Nicoraella germanica Zone,the Nicoraella kockeli Zone,the Paragondolella bulgarica Zone,the Neogondolella constricta Zone,the Neogondolella cornuta Zone,and the Paragondolella excelsa Zone,respectively.The first occurrence of Nicoraella kockeli defines the Bithynian-Pelsonian boundary.The Pelsonian-Illyrian boundary is defined by the first occurrence of Neogondolella constricta.The Anisian-Ladinian boundary cannot be recognized at the Shaiwa Section due to the absence of conodont indicative of the Ladinian.However,the new conodont data indicate that the uppermost strata could be very close to the boundary.The abrasion of conodont surfaces provides evidence for demonstrating reworking at the Shaiwa Section,which makes some conodonts possess a longer stratigraphic range than previously recorded.The variation in relative abundance between blade-shaped conodonts and platform conodonts indicates that segminiplanate elements probably preferred deeper and oxygenated environments whereas a restricted marine environment is more suitable for segminate elements.
文摘顶苏地区晒瓦组以灰色、深灰色薄—中厚层泥质岩屑粉砂岩为主,基本层序由细砂岩—粉砂岩—粘土岩组成,向上粒径变细,层理变薄。在顶苏—小革么—带晒瓦组底发育砾岩层,为晚二叠世沿中二叠统侵蚀面上发育的一套河流相碎屑岩沉积。砾岩层之下灰岩中产牙形石Neogondolella granti Barskov et koroleva,同时根据晒瓦组假整合于峨眉山玄武岩之上,因此晒瓦组为晚二叠世产物。
