藏北羌塘盆地与西亚特提斯盆地构造比较及其油气远景

羌塘盆地是中国西部除塔里木、柴达木、准噶尔盆地外，又一大型古生代一中新生代盆地。与其具有相似构造背景的西亚特提斯带盆地群是目前世界上油气最富集的地区。通过对西亚特提斯带含油气盆地的形成、构造演化背景的分析，探讨了盆地油气富集的地质条件，认为羌塘盆地的形成演化与特提斯西段阿富汗地块具有相似性，侏罗纪的沉积演化和构造格局与中亚的长拉库姆油气盆地类似，故具备形成油气的基本条件。然而，羌塘盆地距喜马拉雅褶皱带较近，新近纪以来构造改造十分强烈。逆冲推覆作用一方面可以产生构造圈闭，但也使烃源岩的成熟度偏高，不利于油气的保存，这与中东地区含油气盆地油气大量聚集的油气田具有显著差异。为此羌塘盆地的油气勘探应寻找保存条件与生油条件相匹配的地区。

Comparison of structures between the Qiangtang basin,northern Tibet, China, and the Tethyan basin, Western Asia, and their petroleum prospect evaluation.

The Qiangtang basin is one large Paleozoic-Cenozoic basin besides the Tarim, Qaidam and Junggar basins in western China. The basin swarm of the West Tethys belt, which is the richest petroleum-bearing region in the world presently, has a similar tectonic setting to the Qiangtang basin. On the basis of an analysis of the formation and tectonic evolution of petroleum-bearing basins in the Tethys belt, the geological conditions for petroleum accumulation in basins are discussed. By a comparative analysis, the authors think that the formation and evolution of the Qiangtang basin are similar to those of the Afghanistan massif in the West Tethys segment and its Jurassic sedimentation and evolution and tectonic framework are similar to those of the Lacum basin in Central Asia. The Qiangtang basin has the basic conditions for petroleum formation. However, the Qiangtang basin is close to the Himalayan fold belt, and since the Neogene the basin has been reworked strongly and nappe-thrusting, on the one hand, generated structural traps but, on the other hand, caused source rocks to be more mature, which is unfavorable for petroleum preservation. Because of these factors, the Qiangtang basin is markedly different from the petroleum-bearing basins in Middle East where petroleum is accumulated in considerable amount. So, we should look for areas with both favorable oil-generating conditions and preservation conditions in petroleum exploration of the Qiangtang basin.