No evidence for a large Mesozoic overthrust in the Lantian area of Anhui Province, south China

This paper presents new geological data from the Lantian area of Anhui Province, SE China, that contradict the hypothesis of the Lantian tectonic window-one of the key argument in Hsü's Mesozoic collision tectonic model for south China. The 1:50,000-scale geological mapping of the Lantian area -located along the eastern part of the Neoproterozoic Jiangnan Belt, confirms that the Sinian-Cambrian strata unconformably overlies the Pre-Sinian formations, and that they form a syncline preserved from early Paleozoic deformation. Pre-Sinian formations (including the Banxi Group distributed in the Jiangnan Belt) do not form a Mesozoic tectonic mélange, but a normal Pre-Sinian stratigraphic sequence. The subsequent tectonic events only slightly transformed the structural framework of this area, which does not exhibit a tectonic window. Thus, these geological data call into question the model of 'Huanan Alps' that invokes large Mesozoic overthrust tectonics in south China. We believe that early Paleozoic tectonic activity has clearly affected the Sinian-Early Paleozoic formations in the Lantian area and given rise to the Jiangnan Belt.