Establishment of GSSP for Guzhangian Stage
After a long-term study in Luoyixi Town, Guangzhang County, the research team led by Prof. Peng Shanchi found that a Lejopyge laevigata of 8 mm in size resembling a peanut first appeared in a set of limestone formations developed in the Luoyixi Section. This is consistent with the location of Lejopyge laevigata that first appeared, marking the beginning of a new phase. It has extensive significance for comparison of international Cambrian strata, and can help solve the problem of accurately comparing strata of Cambrian system all over the world. In view of this, the research team submitted to the IUGS a report on establishing the lower boundary of the 7th Stage of the Cambrian system in Hunan, China, and naming the GSSP with Guzhang County, where the strategraphic section is located.
The Executive Board Meeting of IUGS was held in Morocco in March 2008. In the first round of voting of the Working Group of the International Subcommittee on Cambrian Stratigraphy, the candidate Luoyixi Section defeated the candidate section of Kazakhstan with a 100% of votes to become the only candidate strategraphic section. It was approved with another 100% of votes in the subsequent two rounds of voting by the International Subcommittee on Cambrian Stratigraphy and International Commission on Stratigraphy, which approved to establish the lower boundary GSSP of the 7th Stage of the Cambrian system in Guzhang County, Hunan, China, and to name the stage with Guzhang County, where the strategraphic section is located.
Cross section of GSSP for Guzhangian Stage in the Cambrian System
Luoyixi Section , where the GSSP for Guzhangian Stage in the Cambrian System is located, starts from the lower boundary of Drumian Stage, and ends at the lower boundary of Paibian Stage , with a total length of about 880m. The core part of the GSSP section is about 260m long. The GSSP Section lies in the stratum of Huaqiao Formation, while Lejopyge laevigata which defines the lower boundary of GSSP for Guzhangian Stage, is situated at 121.3 m above the lower boundary of Huaqiao Formation.
The section starts from Drumian Stage (the sixth stage) in the Cambrian System, with Ptychagnostus atavus as the point of first appearance at the lower boundary, and ends at Paibian Stage in the Cambrian System, with Glyptagnostus reticulates as the point of first appearance.
Topographic map of GSSP for Guzhangian Stage
Lejopyge laevigata
Lejopyge laevigata
Cross-section of Guzhangian Stage stratotype
Enlarged view of Guzhangian GSSP section--1
Enlarged view of Guzhangian GSSP section--2
Enlarged view of Guzhangian GSSP section--3
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