Welcome to the Subcommission on Triassic Stratigraphy (STS). Under the auspicities of the International Union of Geological Sciences (IUGS) and International Commission on Stratigraphy (ICS), the STS is charged with the establishment of a standard, globally applicable stratigraphic scale for the Triassic system.
Task Groups of the STS are organizational bodies created for the selection and definition of the lower boundaries of the stages of the Triassic System. Currently, there are six active task groups, and two inactive ones that have completed their tasks.
Base Rhaetian Task Group, M. Balini chair.
Base Norian Task Group, M. Hounslow, chair
Base Carnian Task Group, M. Gaetani, chair. Task Group work completed *
Base Ladinian Task Group, A. Baud, chair. Task Group work completed **
Base Anisian Task Group, M. Balini, chair.
Base Olenekian Task Group, Y. D. Zakharov, chair.
Base Induan Task Group, Yin Hongfu, chair. Task Group work completed ***
Non-marine Boundaries Task Group, S. Lucas, chair.
*In 2008, the base of Carnian Stage was approved by the STS and ratified by the ICS and IUGS. The boundary is defined at the first appearance of the ammonoid Daxatina canadensis (Whiteaves) which is coincident with the base of the D. canadensis subzone of the Trachyceras zone in the Prati di Stuores/Stuores Wissen section of northern Italy.
**In, 2005, the base of the Ladinian Stage was approved by the STS and ratified by the ICS and IUGS. The boundary is defined at the first appearance of the ammonoid Eoprotrachyceras curionii, in the Bagolino section, Province of Brescia, northern Italy.
***In 2001, the base of the Induan Stage (and therefore the Permian/Triassic boundary) was approved through majority vote by the STS and ratified by ICS (Yin et al., 2001). The boundary is defined at the first appearance of the conodont Hindeodus parvus at the base of Bed 27c of Meishan section D, Changxing County, Zhejiang Province, South China.