The Huanghuachang section near Yichang,southern China was successively approved by ISOS,recognized by ICS and then officially ratified as being the Global Stratotype Section and point(GSSP)for the base of the Middle O...The Huanghuachang section near Yichang,southern China was successively approved by ISOS,recognized by ICS and then officially ratified as being the Global Stratotype Section and point(GSSP)for the base of the Middle Ordovician Series and the Third Stage,named as Dapingian,of the Ordovician System.The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus,Gothodus,Microzarkodina and Periodon are represented.The base of the Middle Ordovician Series and the Daping Stage is defined at a point 10.57 m above the base of the Dawan Formation at the base of Bed SHod-16 of the Huanghuachang section,22km NE of Yichang City,Hubei Province,South China.It coincides with the first appearance datum(FAD)of the conodont species Baltoniodus triangularis within the Baltoniodus lineage starting from Baltoniodus cf.B.triangularis to Baltoniodus navis.It is associated with the FAD of Periodon sp.A and followed closely by the FAD of Microzarkodina flabellum,which is taken as a reasonable proxy for the boundary.This level approxi-mates the boundary between the lower and upper Azygograptus suecicus graptolite Biozone,and nearly coincides with the base of the Belonechitina cf.henryi chitinozoan Biozone.The same faunal succession is also recorded from the Chenjiahe section,near Daping village,5 km to the north of the Huanghuachang section.展开更多
基金Research on the Huanghuachang GSSP and preparation of this proposal was financially supported by the China Geological Survey(NO:200113900072)National Natural Science Foundation of China(NO:40272020)the Germany Academic exchange Centre(DAAD),Chinese Commission of Stratigraphy and Yichang Institute of Geology and Mineral Resources(YIGMR).
文摘The Huanghuachang section near Yichang,southern China was successively approved by ISOS,recognized by ICS and then officially ratified as being the Global Stratotype Section and point(GSSP)for the base of the Middle Ordovician Series and the Third Stage,named as Dapingian,of the Ordovician System.The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus,Gothodus,Microzarkodina and Periodon are represented.The base of the Middle Ordovician Series and the Daping Stage is defined at a point 10.57 m above the base of the Dawan Formation at the base of Bed SHod-16 of the Huanghuachang section,22km NE of Yichang City,Hubei Province,South China.It coincides with the first appearance datum(FAD)of the conodont species Baltoniodus triangularis within the Baltoniodus lineage starting from Baltoniodus cf.B.triangularis to Baltoniodus navis.It is associated with the FAD of Periodon sp.A and followed closely by the FAD of Microzarkodina flabellum,which is taken as a reasonable proxy for the boundary.This level approxi-mates the boundary between the lower and upper Azygograptus suecicus graptolite Biozone,and nearly coincides with the base of the Belonechitina cf.henryi chitinozoan Biozone.The same faunal succession is also recorded from the Chenjiahe section,near Daping village,5 km to the north of the Huanghuachang section.
