EARLY TRIASSIC AMMONOID SUCCESSION IN CHAOHU,ANHUI PROVINCE

The uppermost Permian and Lower Triassic are completely exposed in Mt. Pingdingshan and Mt. Ma jiashan , Northwest Chaohu City, Anhui Province, East China, where the Lower Triassic is well developed and composed of the alternations of mudrock and limestone deposited on a deep part of the Lower Yangtze carbonate ramp, containing rich ammonoid fossils. 37 genera and 60 species are recognized from the uppermost Permian and Lower Triassic at the North Pingdingshan Section, West Pingdingshan Section and South Majiashan Section. In addition, many specimens were also collected from the North Majiashan Section and the Guimengguan Section in South Chaohu. A complete Lower Triassic ammonoid zonation can be retrieved in ascending order: Ophiceras Lytophiceras Zone, Gyronites Prionolobus Zone, Flemingites Euflemingites Zone, Anasibirites Zone, Columbites Tirolites Zone and Subcolumbites Zone. The base of the Flemingites Euflemingites Zone is very close to the FAD of conodont Neospathodus waageni at the West Pingdingshan Section, which was proposed as the GSSP of the Induan Olenekian boundary. This paper describes some better preserved ammonoid fossils of biostratigraphic importance with emphasis on those around the Induan Olenekian boundary, plus a few specimens from the uppermost Permian Tapashanites Pleuronodoceras Zone.

Project Supported:

Clc Number:

Q914.2