GSSP for Changhsingian Stage
Definition:
The Base of the Changhsingian Stage is defined at the base of Bed 4a-2, 88 cm above the base of the Changxing Limestone at the Meishan D Section, just above a flooding surface marking the second parasequence in the Changxing Limestone. The GSSP coincides with the FAD of the conodont species Clarkina wangi within the lineage from Clarkina longicuspidata to Clarkina wangi.
The section is located at the Meishan Section D, Changxing County, Zhejiang Province between Nanjing and Shanghai, China at a latitude of 31°4'55"N and a longitude of 119°42'22.9"E and is freely accessible and well protected.
The exposure at the Meishan D section contains only the uppermost part of the Longtan Formation. These beds include earthy yellow, calcareous siltstone and mudstone with horizontal beds of increasing thickness that contain ammonoids and brachiopods. This bed appears to be conformable with the overlying Baoqing Member of the Changxing Limestone.
The lowest bed (Bed 2) of the Changxing Limestone at section D, which is represented by dark grey, thick-bedded silty wackestone, appears to form the upper part of a cycle or parasequence.
Bed 3 contains greyish black calcareous mudstone and thin-bedded argillaceous mudstone that may represent the flooding unit of a second parasequence in the section.
Beds 4 and 5 include thin to medium bedded wackestone and represent the regressive portion of this second parasequence.
Primary Markers:
The base of the Changhsingian Stage is defined at the FAD of the conodont species Clarkina wangi within the lineage from Clarkina longicuspidata to Clarkina wangi at the base of Bed 4a-2
Secondary Markers:
Ammonites
The ammonoid Sinoceltites has its first occurrence in the same bed as Clarkina wangi. The first occurrence of the ammonoid Tapashanites is only 42 cm above the GSSP.
Fusulinaceans
Palaeofusulina aff. sinensis has its first appearance together with Clarkina wangi in Bed 4a-2.
Correlation Events:
Conodont FAD Clarkina wangi
Notes on Derivation of Age:
Permian-Carboniferous time scale is derived from calibrating a master composite section to selected radiometric ages.