Role of Basin Filling Patterns on the Evolution of Carbonate Platform Margin Architecture

Abstract

Previous studies have addressed the role of siliciclastic basin infill on accommodation space and consequent influence on progradation geometry of carbonate platforms. Few studies have addressed the role of siliciclastic basin fill on carbonate platform margin evolution from a basin-wide perspective. In order to analyze the impact of siliciclastic turbidite basin infill on platform architecture, this study integrates a regional analysis of turbidite provenance and compares evolution of Triassic margin architecture of the Great Bank of Guizhou (an isolated platform) in the Nanpanjiang Basin of South China and its adjacent extensive attached Yangtze Platform. In the Yangtze Platform, earlier arrival of Anisian siliciclastic turbidites sourced from the Jiangnan uplift in the eastern area filled the basin margin at Guiyang, producing a substratum above which the platform could prograde basinward. In the western area at Guanling, synchronous infilling of the basin margin allowed intertonguing and promoted stability of the margin and vertical aggradation. Later arrival of the turbidite basin fill distant from the Jiangnan uplift coupled with high subsidence rates caused margin instability and development of a backstepped and gravitational collapse architecture in the Zhenfeng and Anlong areas. Likewise in the Great Bank of Guizhou, earlier arrival (Anisian) and infilling of the basin by turbidites resulted in progradation of the platform margin in the Xiliang area proximal to the Jiangnan uplift, whereas in western areas distal from the siliciclastic sources the platform aggraded to develop extreme relief and gravitationally collapsed margins. High rates of subsidence coupled with the lack of basin infilling locked the platform into aggradational growth and resulted in the development of a high-relief escarpment architecture and large-scale gravitational collapse. The timing and pattern of basin infill impacts carbonate platform evolution in a regionally predictable pattern: early infill enables margin progradation in areas proximal to siliciclastic sources, whereas late infill in platform areas distant from sources results in aggradation and development of extreme platform margin relief with large-scale gravitational sector collapse.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015