CHARACTERISTICS AND DISTRIBUTION OF DEPOSITIONAL SYSTEMS OF SILURIAN IN TARIM BASIN

In order to determine sedimentary facies types and their distribution in Tarim basin, based on the recent sedimentology and sequence stratigraphy, a lot of coring data, well logging and seismic data from Silurian in Tarim basin were comprehensively studied. The Silurian of study area was divided into two types of sedimentary sequences. It mainly developed offshore depositional system with high maturities of content and texture, swash bedding and prograted sequence, and also developed a shelf and slope depositional system with a plenty of bioturbation structure and alternating sandstone mudstone. But it lacked the clastic tidal flat depositional systems with the plane and barrier bar. The sedimentary characteristics and distributions of the above depositional systems were analyzed. The sedimentary models of clastic coast and tidal flat were found. The sedimentary center of Silurian was determined at the Manjiaer depression. The transgression direction was from east to west in Tarim basin. The relations of deposional systems with source rock, reservoir and capping bed show that the sandstones in the southern slope of Tabei uplift and the northern slope of Tazhong uplift are the faverable exploration targets.