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赫南特阶(上奥陶统)的全球界线层型剖面和点位确立在中国宜昌王家湾北剖面观音桥层底界之下0.39m处。该剖面位于中国湖北省宜昌市以北42km处的王家湾村,经纬度为30°58′56″N、111°25′10″E。赫南特阶底界的GSSP点位以笔石Normalograptusextraordinarius的首次出现层位(FAD)为标志。碳同位素在此层位显示的正漂移以及N.ojsuensis的首现可作为第二标志。赫南特阶始于自Diceratograptusmirus亚带开始的全球生物大灭绝事件的主幕之后。王家湾北剖面出露完整,沉积和生物序列连续,笔石和壳相动物化石丰富并保存良好,王家湾北、王家湾南和王家湾小河边剖面都发育了合适的沉积相和生物相并具有广泛对比的潜力。该地区地质构造简单,岩石未经历较强的变质作用,且交通便利。王家湾小河边剖面尤其适合进行化学地层学研究和同位素年龄的测定。建立赫南特阶底界的全球界线层型剖面和点位的提案报告于2004年10月被国际地层委员会奥陶系分会通过,经补充完善后,于2006年2月被国际地层委员会通过,同年5月被国际地科联正式批准。
The global boundary stratigraphic profile and site of the Hernán Nantelese (Upper Ordovician) were established at 0.39 m below the bottom boundary of the Guanyinqiao layer in the north section of Wangjiawan, Yichang, China. The profile is located at Wangjiawan Village, 42km north of Yichang City, Hubei Province, China. The latitude and longitude are 30 ° 58’56 “N and 111 ° 25’10” E. The GSSP of the Hernández-Oddi boundary is marked by the first occurrence of FAD in Normalograptusextraordinarius. The positive shift of the carbon isotopes at this horizon and the first appearance of N. ojsuensis can serve as secondary markers. The Hernándezian sequence follows the main curtain of the global mass extinction that began with the Diceratograptusmirus sub-band. The north profile of Wangjiawan is complete with continuous sedimentary and biological sequences, rich and well preserved petroglyphic and shell facies fossils, and suitable sedimentary facies and biofacies have been developed in both Wangjiawanbei, Wangjiawanan and Wangjiawan profiles Potential for broad comparison. Geological structure in the area is simple, the rock has not undergone a strong metamorphism, and convenient transportation. The Wangjiawan small river profile is particularly suitable for chemical stratigraphy and isotopic dating. The report on the proposal of establishing a global boundary layer profile and point for the Hernández-Degenerate bottom boundary was adopted by the Ordovician Branch of the International Stratigraphy Commission in October 2004. After being supplemented and supplemented, it was passed by the International Stratigraphy Commission in February 2006, May the same year by the International Federation of Lands officially approved.