Distribution and Controlling Factors of Siliceous Sponge Reefs in Western Sichuan Province
川西上三叠统海绵生物礁的分布及其控制因素

The Maantang Formation in western Sichuan basin was probably located in the shelf of the passive continental margin in Upper Triassic. The kind of the Carnian siliceous reefs distributed along the Longmenshan Mountain is patch reef in western Sichuan. The complex of a reef is composed of reef base, reef core, reef flank and reef cap. The distribution of reefs is affected by such factors as properties of siliceous sponge, sediment environment, tectonic settings, biotic guild, temperature, oxygen-bearing zone, ocean current and suspend nutrient. Based on these factors, the authors hold that the reefs in a NE-SW extending belt are distributed in a continental shelf ca. 100 meters below the sea level. A part of the reefs is now exposed on the surface, and about 20 kinds of reefs have been discovered. The other part of the reefs might be covered by thrust blocks and overlying strata. It is evident that the reef complex is of good petroleum potential and exploration prospects.