The Global Stratotype Section and Point(GSSP)for the Cretaceous/Paleogene(K/Pg)boundary was defined at the base of the boundary clay at a section near El Kef,Tunisia,but the outcrop became quite deteriorated.In order ...The Global Stratotype Section and Point(GSSP)for the Cretaceous/Paleogene(K/Pg)boundary was defined at the base of the boundary clay at a section near El Kef,Tunisia,but the outcrop became quite deteriorated.In order to better characterize the boundary and to solve problems of correlation,several auxiliary sections are designed and described in detail including:Aïn Settara and Ellès in Tunisia,Caravaca and Zumaya in Spain,Bidart in France and El Mulato and Bochil in Mexico.These sections are the most continuous,expanded and representative of marine sedimentation in areas proximal and distal to the Chicxulub meteorite impact site.展开更多
The Kyrshabakty section in the Malyi Karatau Range,southern Kazakhstan,has been approved as the Auxiliary boundary Stratotype Section and Point(ASSP)for the base of the Jiangshanian Stage of the Furongian Series(Cambr...The Kyrshabakty section in the Malyi Karatau Range,southern Kazakhstan,has been approved as the Auxiliary boundary Stratotype Section and Point(ASSP)for the base of the Jiangshanian Stage of the Furongian Series(Cambrian System).The first appearance datum(FAD)of the agnostoid trilobite Agnostotes orientalis coincides with the horizon marking the base of the Jiangshanian Stage,and the FAD of A.orientalis occurs at 259.0 m in the measured section,61.2 m above the base of Unit 8 in the Zhumabai Formation.The boundary interval in the Kyshabakty section shows a relatively monotonous succession of carbonate deposits.The section contains an abundance of Cambrian fossils including diverse trilobites,brachiopods,molluscs,bradoriids,protoconodonts and paraconodonts.展开更多
The global Hangenberg Crisis or Hangenberg Extinction is a mass extinction near the Devonian-Carboniferous boundary.Comprehensive research of petrology and geochemistry on the Devonian-Carboniferous boundary,as expose...The global Hangenberg Crisis or Hangenberg Extinction is a mass extinction near the Devonian-Carboniferous boundary.Comprehensive research of petrology and geochemistry on the Devonian-Carboniferous boundary,as exposed in the Nanbiancun auxiliary stratotype section,South China,elucidates paleoenvironmental changes and controls on marine strontium(^(87)Sr/^(86)Sr)and carbonate carbon(δ^(13)C_(carb))isotopes during the Hangenberg Crisis.The new^(87)Sr/^(86)Sr data reveal a regression in the Middle Siphonodella praesulcata Zone,while the Hangenberg Extinction was occurring in South China.Moreover,theδ^(13)C_(carb)data records a negative excursion near the base of the Middle Siphonodella praesulcata Zone that may have been connected with the Hangenberg Extinction.A positiveδ^(13)C_(carb)excursion,corresponding with the Upper Siphonodella praesulcata Zone,may reflect the effects of a vigorous biological pump.The magnitude of the Hangenberg Carbon Isotopic Excursion in peakδ^(13)carb values andδ^(13)C_(carb)gradient in carbonate Devonian-Carboniferous boundary sections of the South China Craton during the Hangenberg Crisis,are a function of depositional water depth and distance from the shore.The carbon cycling during the Hangenberg Carbon Isotopic Excursion had a much stronger impact on oceanic surface waters than on the deep ocean and theδ^(13)C_(carb)gradient of local seawater was likely caused by enhanced marine productivity,associated with biological recovery in platform sediments during the Hangenberg Crisis.展开更多
基金funded by the IUGS,the Spanish Ministerio de Educación y Ciencia(Consolider project CGL2007-63724 and AECI project A/4845/06)the Aragonian Departamento de Educación y Ciencia(DGA group E05)L.Alegret acknowledges support from a Ramon y Cajal research contract from the Spanish Ministry of Science and Technology.
文摘The Global Stratotype Section and Point(GSSP)for the Cretaceous/Paleogene(K/Pg)boundary was defined at the base of the boundary clay at a section near El Kef,Tunisia,but the outcrop became quite deteriorated.In order to better characterize the boundary and to solve problems of correlation,several auxiliary sections are designed and described in detail including:Aïn Settara and Ellès in Tunisia,Caravaca and Zumaya in Spain,Bidart in France and El Mulato and Bochil in Mexico.These sections are the most continuous,expanded and representative of marine sedimentation in areas proximal and distal to the Chicxulub meteorite impact site.
文摘The Kyrshabakty section in the Malyi Karatau Range,southern Kazakhstan,has been approved as the Auxiliary boundary Stratotype Section and Point(ASSP)for the base of the Jiangshanian Stage of the Furongian Series(Cambrian System).The first appearance datum(FAD)of the agnostoid trilobite Agnostotes orientalis coincides with the horizon marking the base of the Jiangshanian Stage,and the FAD of A.orientalis occurs at 259.0 m in the measured section,61.2 m above the base of Unit 8 in the Zhumabai Formation.The boundary interval in the Kyshabakty section shows a relatively monotonous succession of carbonate deposits.The section contains an abundance of Cambrian fossils including diverse trilobites,brachiopods,molluscs,bradoriids,protoconodonts and paraconodonts.
基金financially supported by the National Natural Science Foundation of China(92055208)Guangxi Natural Science Foundation for Distinguished Young Scholars(2018GXNSFFA281009)+3 种基金the CAS‘Light of West China’Program(2018-XBYJRC-003)the Guangxi Science Innovation Base Construction Foundation(Guike ZY21195031)the Fifth Bagui Scholar Innovation Project of the Guangxi Province(to Xu Jifeng)the grant of the Laboratory for Marine Geology,Qingdao National Laboratory for Marine Science and Technology(MGQNLM201901)。
文摘The global Hangenberg Crisis or Hangenberg Extinction is a mass extinction near the Devonian-Carboniferous boundary.Comprehensive research of petrology and geochemistry on the Devonian-Carboniferous boundary,as exposed in the Nanbiancun auxiliary stratotype section,South China,elucidates paleoenvironmental changes and controls on marine strontium(^(87)Sr/^(86)Sr)and carbonate carbon(δ^(13)C_(carb))isotopes during the Hangenberg Crisis.The new^(87)Sr/^(86)Sr data reveal a regression in the Middle Siphonodella praesulcata Zone,while the Hangenberg Extinction was occurring in South China.Moreover,theδ^(13)C_(carb)data records a negative excursion near the base of the Middle Siphonodella praesulcata Zone that may have been connected with the Hangenberg Extinction.A positiveδ^(13)C_(carb)excursion,corresponding with the Upper Siphonodella praesulcata Zone,may reflect the effects of a vigorous biological pump.The magnitude of the Hangenberg Carbon Isotopic Excursion in peakδ^(13)carb values andδ^(13)C_(carb)gradient in carbonate Devonian-Carboniferous boundary sections of the South China Craton during the Hangenberg Crisis,are a function of depositional water depth and distance from the shore.The carbon cycling during the Hangenberg Carbon Isotopic Excursion had a much stronger impact on oceanic surface waters than on the deep ocean and theδ^(13)C_(carb)gradient of local seawater was likely caused by enhanced marine productivity,associated with biological recovery in platform sediments during the Hangenberg Crisis.
