Carbonate Facies and Facies Models

Key words: 
• carbonate rocks /
• facies /
• depositional model /
• platform /
• slope /
• basin

Abstract: Carbonate rocks are widespread in China, and are important exploration targets for oil and gas. About carbonate facies and facies models, there still exist many problems to be solved, including chaotic nomination of facies, different names for the same environments, different meanings for the same name, incomplete facies models, obscure identification marks in such facies models and difficult application, and so on. In this paper, based on the author's experience of  long term  study on carbonate rocks and previous studies on modern and ancient carbonate environments, some carbonate facies are redefined, such as platforms, slopes and basins are classified into different types. Carbonate platforms are divided into islolated platform, rimmed platform and offshore platform. Rimmed platform is further divided into steep-slope rimmed platform and gentle-slope rimmed platform; offshore platform is further divided into steep-slope offshore platform and gentle-slope offshored platform. Slope is divided into gentle slope, steep slope and steep cliff. Basin is divided into shallow basin and deep basin. Origin and evolution sequence of platforms are analyzed, and platform evolution is divided into primary stage, early stage, middle stage and late stage. In different stages, platforms show different characteristics. Depositional models of different types of platforms and key characteristics of different facies are summarized.