The quest for internationally recognized divisions of Cambrian time

Abstract

the system currently has no formally agreed internationally recognized divisions. Since the IUGS Commission on Stratigraphy requires the definition of Global Boundary Stratotype Sections and Points (GSSPs), it has become the prime objective of the International Subcommission on Cambrian Stratigraphy to commence to document suitable biostratigraphic horizons within the system which might assist in achieving this goal. In this paper we suggest the consideration of fourteen late Early Cambrian-terminal Cambrian levels, and document their stratigraphical and biogeographical distributions. Once agreement within the Subcommission is reached on which are the most suitable, it will be necessary to search for appropriate stratotype sections, bearing in mind the necessity to calibrate the biostratigraphy by way of non-biological correlation techniques, such as chemostratigraphy and magnetostratigraphy.

Carbon and oxygen isotopic composition of Lower to Middle Cambrian sediments at Taijiang, Guizhou Province, China

“…More precisely, the boundary level is located at the base of bed 15 (at 52.8 m) (Zhao et al 2001a,b). In addition, this position of the boundary level is further supported by acritarch studies (Yin & Yang, 1999;Moczydłowska, 1999;Geyer & Shergold, 2000;Yang & Yin, 2001). Yuan et al 1997;Sundberg & McCollum, 1997).…”

THE DEMOSPONGE GENUS LEPTOMITUS and A NEW SPECIES FROM THE MIDDLE CAMBRIAN OF SPAIN

“…The Lower/Middle Caesaraugustan transition may be correlated with the Tomagnostus fissus and/or Acidusus atavus zones, which have been correlated with the lower part of the Bolaspidella Zone (Marjuman Stage) in the Laurentian scale (Text‐fig. 3, and correlation chart in Geyer and Shergold 2000).…”

Fallotaspidoid trilobite assemblage (Lower Cambrian) from the Esmeralda Basin (western Nevada, U.S.A.): The oldest trilobites from Laurentia

“…This terminology is badly in need of revision as indicated by recent field studies in the western Laurentia (Palmer & Halley 1979;Palmer & Repina 1993;Bohach 1997;Fowler 1999;Hollingsworth 1999aHollingsworth , 2005a and it fails to provide sufficient detail for comparison with other Cambrian continents (Geyer & Shergold 2000). The earliest of these zones, the 'Fallotaspis' Zone, was identified by Fritz (1972) as containing similar trilobites to those in Hupé's (1953) Zones I to IV in the Anti-Atlas Mountains of Morocco.…”