Sequence Stratigraphic Analysis of the Neodevonian—Carboniferous in the Tarim Basin

Key words: 
• sequence /
• system tracts /
• Tarim Basin /
• the Neodevonian-Carboniferous /
• sea level /
• tectonism

Abstract: Tarim Basin, enclosed or semienclosed by the paleocontinent or islands on the south, north and east, was the vast epicontinental sea on the continental shelf in the Neodevonian- Carboniferous which formed a series of multi type and multicyclic carbonate rocks, evaporites, clastic rocks and transitional rocks. The sequence stratigraphic patterns of the Tarim Basin are different from those proposed by P. R. Vail et al. mainly on the basis of passive continental margin basins. The Neodevo nian-Carboniferous of the Tarim Basin can be divided into fives equences and subdivided into fourteen system tracts. The Sequence I was formed under the conditions of the rising of sea level and quick compensation of more terrigenous clastic materials. The SequenceⅡ formed in an environment in which the feeding of terrigenous materials changed from quick to slow. The Sequence Ⅲ formed in an environment in which the rising of sea level changed from quick to slow and the feeding of terrigenous clastic was relatively constant. The SequenceⅣ formed in an environment in which the rising rate of sea level gradually slowed down and terrigenous clastic feeding was relatively constant, and the SequenceⅤ formed in an environment of quick rising of sea level and lacking of terrigenous clastic feeding. The Neodevonian-Carboniferous deposition in the Tarim Basin occurred during a general transgression process of rising of the relative sea level by stages. The changes of the sea level in the Neodevonian～Carboniferous may be divided into five 3rnd-order cycles, of which the generation of the CycleⅠ、Ⅱ、Ⅴ were mainly controlled by the regional tectonism and the others by the eustasy.