The Evolution and Main Controlling Factors of Reef and Carbonate Platform in Wan'an Basin

Yang Zhen; Zhang Guangxue; Zhang Li

doi:10.3799/dqkx.2016.107

Abstract：The reef and carbonate platform is one of the most important reservoirs in the south of South China Sea,and the reefs and the sedimentary facies of carbonate platform in the Wan'an basin should be further studied.The high-resolution seismic profiles associated with well data in this paper facilitate the understanding of the reefs and carbonate platforms in the study are-a.The evolution of reefs and carbonate platform can be divided into four stages.In Early Miocene,a few isolated carbonate platforms that were small in size firstly initiated in center of this basin.They flourished in Middle Miocene and mainly devel-oped around the Northern Uplift,Central Uplift.Transversely,two bands there,namely western band and eastern band,were the distinct characteristic of its spatial distributions in this time.Platform-edge reef and massive reef were the main style of reef and there were also a few point reefs developing on the edge of carbonate platform.In Late Miocene,the carbonate platforms began to backstep to elevated topographic positions in response to a relative sea level rise.While,the number and style of reef increased in this stage,such as platform-edge reef,massive reef,atoll reef and point reef.Tectonics and eustasy are the two main controlling factors on platform development.Tectonics mainly controlled both the initial topography for reef growth and the distribution of platforms,and eustasy controlled carbonate sequence development.Since the Late Miocene,the rapid tec-tonic subsidence and the rise of relative sea-level should have led to the drowning of carbonate platform.