The Changhsingian foraminiferal fauna of a Neotethyan seamount: the Gyanyima Limestone along the Yarlung-Zangbo Suture in southern Tibet, China

The Gyanyima Limestone is one of the isolated carbonate build-ups that have a probable Neotethyan seamount origin, distributed along the Yarlung-Zangbo Suture in southern Tibet. The limestone yields a highly diversified foraminiferal fauna consisting of nine fusuline and 37 taxa of non-fusuline foraminifers. This foraminiferal fauna is dominated by Reichelina pulchra, Colaniella parva and the characteristic boultoniid genus Dilatofusulina. We propose a new foraminiferal zone, the Reichelina pulchra-Colaniella parva-Dilatofusulina orthogonios Zone that represents the last prosperous stage of foraminifers just before the end-Permian mass extinction. This zone can be correlated broadly with the Palaeofitsulina sinensis Zone in the Eastern Tethys based on advanced features observed in the major elements of the fauna. The composition of the fauna suggests that during the late Changhsingian, the Gyanyima Limestone occupied a palaeogeographic position at lower latitudes in the Neotethys. The fauna was largely influenced by the warm-water equatoro-tropical Palaeotethys. Copyright (C) 2010 John Wiley & Sons, Ltd.