This paper presents a comprehensive evaluation on the Devonian-Carboniferous Boundary (DCB) sectionin Nanbiancun. Guilin. Guangxi on the basis of Palaeontological, biostratigraphical and sedimentarypetrological studie...This paper presents a comprehensive evaluation on the Devonian-Carboniferous Boundary (DCB) sectionin Nanbiancun. Guilin. Guangxi on the basis of Palaeontological, biostratigraphical and sedimentarypetrological studies as well as microfacies analysis. REE and trace element analysis and isotopic dating. The DCB at this section conforms to the definition of this boundary and essentially measure up the criteriaand conditions for selection of the boundary stratotype. Up to 14 fossil groups are contained in the section. Thesection presents a general biostratigraphical framework with multispecies fossils zones, assemblage zones andmultiple groups of fossils and has latent preponderant conditions for magnetostratigraphic andchronostratigraphic studies. The boundary and point occur in a persistent and continuous monofacialcarbonate succession. and the section is located in a tourist city with convenient communication, where variousfacies of DCB sections are developed. allowing the correlation within a small area. So it is an ideal candidateboundary stratotype.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
文摘This paper presents a comprehensive evaluation on the Devonian-Carboniferous Boundary (DCB) sectionin Nanbiancun. Guilin. Guangxi on the basis of Palaeontological, biostratigraphical and sedimentarypetrological studies as well as microfacies analysis. REE and trace element analysis and isotopic dating. The DCB at this section conforms to the definition of this boundary and essentially measure up the criteriaand conditions for selection of the boundary stratotype. Up to 14 fossil groups are contained in the section. Thesection presents a general biostratigraphical framework with multispecies fossils zones, assemblage zones andmultiple groups of fossils and has latent preponderant conditions for magnetostratigraphic andchronostratigraphic studies. The boundary and point occur in a persistent and continuous monofacialcarbonate succession. and the section is located in a tourist city with convenient communication, where variousfacies of DCB sections are developed. allowing the correlation within a small area. So it is an ideal candidateboundary stratotype.
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.
