The Global Boundary Stratotype Section and Point (GSSP) for the base of the Hirnantian Stage (the uppermost of the Ordovician System)

Xu Chen, Jiayu Rong, Junxuan Fan, Renbin Zhan, Charles E. Mitchell, David A.T. Harper, Michael J. Melchin, Ping'an Peng, Stan C. Finney, Xiaofeng Wang
2006 Episodes  
The GSSP level coincides with the first appearance of the graptolite species Normalograptus extraordinarius (Sobolevskaya). Secondary markers include the onset of a positive carbon-isotope excursion, and a slightly earlier first appearance of Normalograptus ojsuensis (Koren and Mikhailova). The Wangjiawan North section possesses continuity of sedimentation and biozonation with completeness of exposures, abundant and well-preserved graptolites and shelly fossils, i. e. the Hirnantia-Dalmanitina
more » ... helly fauna which is a key element for recognition of the Hirnantian Stage. The Wangjiawan North, South and Riverside sections possess favorable facies and widespread correlation potential, are free from structure complication, metamorphism and other alteration, and have good accessibility. The Riverside section in particular possesses amenability to isotopic age determination. The beginning of the Hirnantian was followed by a global episode of a major extinction event, which happened in the Diceratograptus mirus Subzone.
doi:10.18814/epiiugs/2006/v29i3/004 fatcat:vsjlknv5g5hqne5x5dmr3txp6u