South China Sea carbonate build-up seismic characteristics

More than 600 active reefs in the Spratly Islands and 200 build-ups in Central Luconia, buried in the Upper Miocene, all begun at the Middle Miocene Unconformity. Their seismic character results from the subsidence regime of the marginal basin. Central Luconia build-ups within the continental shelf remained in shallow water and were buried by an Upper Miocene influx from nearby Sarawak, known onland as the Setap Shale. Build-ups within the continental rise (Dangerous Grounds) and North-West Borneo Trough were drowned by rapidly deepening water then occasionally draped over by a thin layer of deep water sediments. Spratly Islands reef builders colonized cuesta highs and kept pace with the deepening sea. The build-ups now continued to be active and none were drowned. Young sediment influx could only settle as thin ponded turbidites within the sea between the reefs that had deepened to at least 1.8 km.