The Global Boundary Stratotype Section and Point (GSSP) of the Guzhangian Stage (Cambrian) in the Wuling Mountains, Northwestern Hunan, China

Abstract

each series it is expected that two to three stages whose boundaries correspond to horizons that can be correlated with a high degree of confidence through all paleocontinents will be recognized. As emphasized by Geyer and Shergold (2000), communication of timestratigraphic information will be maximized if the internal subdivisions of the system correspond to horizons recognizable on all paleocontinents. Traditional, regional stratigraphic schemes, based principally on unit stratotypes, do not meet this goal, and it is for this reason that the ISCS is now engaged in further developing our understanding of key horizons for correlation within the Cambrian, and newly defined series and stages that are readily traceable among Cambrian regions. The newly defined chronostratigraphic units are based on the principle of boundary stratotypes, in which the base of one unit (marked by a Global boundary Stratotype Section and Point, or GSSP) automatically delimits the top of the underlying unit. So defined, these intervals differ in substance from unit stratotypes, which have been variously defined in Cambrian regions (Geyer and Shergold, 2000; Peng et al., 2004a, 2006; Babcock et al., 2005). Apart from the Guzhangian Stage (discussed here), the boundary positions relevant to the Cambrian (Figure 1) that have been ratified are: 1, the conterminant base of the Paleozoic Erathem, Cambrian System,

Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

“…The base of the Drumian Stage coincides with the First Appearance Datum (FAD) of Ptychagnostus atavus (also published as Acidusus atavus; ). The base of the Guzhangian Stage coincides with the FAD of Lejopyge laevigata (Peng et al 2009b). The base of the Paibian Stage coincides with the FAD of Glyptagnostus reticulatus (Peng et al 2004a).…”

“…The base of the Guzhangian Stage coincides with the FAD of Lejopyge laevigata (Peng et al . ). The base of the Paibian Stage coincides with the FAD of Glyptagnostus reticulatus (Peng et al .…”

“…), and each of the other defined stage bases is identifiable primarily by the first appearance of a cosmopolitan agnostoid species (Peng et al . , ; Peng et al . ; Babcock et al .…”

“…Of these, two series (Terreneuvian and Furongian) and five stages (Fortunian, Drumian, Guzhangian, Paibian and Jiangshanian) are now ratified. The primary evolutionary marker for the conterminous Terreneuvian Series/Fortunian Stage base is a trace fossil Landing 1994;Landing et al 2007), and each of the other defined stage bases is identifiable primarily by the first appearance of a cosmopolitan agnostoid species (Peng et al 2004a(Peng et al , 2009bPeng et al 2012b;). The ratified GSSPs for the Drumian, Guzhangian, Paibian and Jiangshanian stages (Fig.…”

“…;Shergold et al 1990;Ahlberg 2003;Fatka et al 2004;Peng et al 2004aPeng et al , 2009b Peng et al 2012a,b;Peng & Babcock 2005b;Axheimer et al 2006; Jago et al 2006;Ahlberg et al 2007;Babcock et al , 2011Ergaliev & Ergaliev 2008;Ahlberg & Terfelt 2012;Peng et al 2015; but seeWestrop et al 2011 for a contrasting view).…”