Microfacies and enrichment pattern of fossils in the fossiliferous beds of Luoping Biota, Yunnan Province

Abstract：Shangshikan stratigraphic section in Luoping of Yunnan Province is a representative fossiliferous bed that produced Luoping Biota. According to the standard microfacies model put forward by Wilson (1975), the authors recognized six types of microfacies, i.e., marlite, bioclastic wackestone, pelleted-bioclastic marlite, laminated micrite, bioclastic packstone and calcirudite, in the fossiliferous bed of Shangshikan section. The fossiliferous bed can be subdivided into two horizons: the Upper Fossil Horizon (UFH) and the Lower Fossil Horizon (LFH). The relationship between microfacies and fossil enrichment in each fossiliferous horizon was further studied. The result reveals that four kinds of microfacies are mainly developed in the fossil-enriched horizons, comprising marlite, bioclastic wackestone, pelleted-bioclastic marlite and laminated micrite, whose assemblage always occurs in the deep, low-energy intra-platform basin. The water in this environment implies a high anoxic and retained condition, This study shows that this intra-platform basin is highly anoxic and retained, which is suitable for the preservation of fossils.