Depositional Architecture and Facies of a Complete Reef Complex Succession: A Case Study of the Permian Jiantianba Reefs, Western Hubei, South China

Abstract

The Upper Permian Changhsingian Jiantissanba reef complex is a well-known platform marginal reef, located in the western Hubei Province, China. Based on field observations and lithological analysis of the entire exposed reef complex, 12 reef facies have been distinguished according to their sedimentary components and growth fabrics. Each of the lithofacies is associated with a specific marine environment. Vertically traceable stratal patterns reveal 4 types of the lithologic associations of the Jiantianba reef: (1) heterozoan reef core association: developed in the deep marginal platform with muddy composition; (2) photozoan reef core association developed within the photic zone; (3) tide-controlled reef crest association with tidal-dominated characteristic of lithofacies in the shallow water; and (4) reef-bank association dominated by bioclastic components. The entire reef complex shows a complete reef succession revealing a function of the wave-resistant and morphological units. This study displays a complete sedimentary succession of Jiantianba reef, which provides a more accurate and comprehensive description of the reef lithofacies and a better understanding of the structure and composition of organic reefs.

Thickness Variation Characteristics of Tidal Rhythmites—An Example From the Pinghu Formation, Xihu Sag, East China Sea Shelf Basin

“…Wavelet analysis not only retains the advantages of the Fourier transform but also makes up for the deficiency that the Fourier transform cannot reflect signal characteristics in local time (space). Many scholars have introduced this method into a high-precision sequence unit division to amplify the information in logging signals and to identify sequence cycles of different levels (Zhu et al, 2010;Chen et al, 2018;He, 2020;Fontana et al, 2021). Through frequency division processing on the data on variation in the thickness of sandy laminae, argillaceous laminae, and couplets, the frequency division signal was extracted and compared with the sedimentary facies divided by core observations, and the corresponding relationship between the frequency signal and sedimentary facies was summarized.…”