## 1 Introduction  
Carbonate platforms are mainly distributed in tropical and subtropical low-latitude ocean shallow water areas, and their growth and development are very sensitive to environmental changes, such as water depth, temperature, waves, salinity, dissolved oxygen, sediment and nutrients [1, 2, 3, 4]. Changes in any of these controlling factors may alter the sedimentary structures of carbonate rocks and even cause their submerged death. Since the Cenozoic, the South China Sea has benefited from its advantageous geographical location (0-23\({}^{\circ}\) N) and suitable climate conditions; because of these, abundant carbonate platforms formed [1, 2, 3]. Though most of these carbonate platforms have been submerged, they still recorded a great deal of important information about the evolution of the South China Sea and also are the main producing reservoirs of hydrocarbon exploration in this area. More than 50 carbonate-type oil/gas fields have been uncovered so far [1, 2, 3, 4]. Previous studies found that the carbonate platforms in the southern part of the South China Sea initially developed in the Middle Oligocene, earlier than in the north [5], and their scales were much larger than in the north.  
The Miocene carbonate platforms in the southern South China Sea were mainly found in the Liyue Basin, the Zengmu Basin and the Wan'an Basin [6; 7; 8; 9; 10]. Among them, the Wan'an Basin is close to the Indochina Peninsula, as shown in Figure 1, and its characteristics and evolution have certain particularities. [PERSON] et al. [7] used drilling and seismic data to reveal that the Northern Palawan Platform on the periphery of the Liyue Basin is an isolated platform developed on the shoulder of the oblique fault block. The Luconia carbonate platform in the Zengmu Basin began to develop in the Early Miocene. After the Miocene, the carbonate platform in the northern part of the Nankang Platform continued to develop, while most of the carbonate platform in the south was covered by progressive delta siliceous clastic rocks. Three-dimensional seismic and well data in the central area of Luconia show that the cause of the inundation of the northern platform may be the rapid rise of relative sea level or sea eutrophication, which is similar to the inundation of the Liuhua Platform (Miocene) in the northern part of the South China Sea [11; 12].  
Figure 1: The location of study area in the South China Sea. The red enclosed area is the Wan’an Basin.  
Based on some seismic data, previous researchers determined that the carbonate platforms of Wan'an Basin have the characteristics of east and west zoning, initially developed in the Early Miocene period and experienced uplifting and denudation in the Late Middle Miocene period [9; 10; 13; 14; 15].  
However, due to the limited seismic and drilling data, the structure and development process of the carbonate platforms in Wan'an Basin are still unclear. Recently, using nine drilling wells, well log data and reprocessed high-quality seismic data, the attempt was made to achieve three goals: (1) finely characterize the seismic reflection structures of reefs and carbonate platforms (hereinafter referred to as RCPs); (2) determine the distribution and evolution of RCPs; (3) clarify the main controlling factors including tectonic activities, terrestrial elastic input processes and relative sea level changes to investigate the development and evolution of RCPs.