【摘要】 松潘-阿坝地区在区域构造演化过程中,经历两个主要拉张-挤压构造阶段。一是由元古代晚期中国古陆解体开始,在早古生代形成分隔扬子地块与华北地块的天山-祁连-秦岭洋,在松潘-阿坝地区北缘发育被动陆缘盆地。早古生代洋盆随原特提斯的消亡,经加里东期的俯冲,扬子地块与华北地块碰撞,最终形成加里东俯冲造山带,由此导致被动陆缘盆地的反转。二是在晚古生代以来,随着古特提斯洋的扩张,在扬子西缘出现的裂陷槽及其间的小洋壳,松潘-阿坝地区西(南)缘形成张裂大陆边缘,发育浊流沉积盆地。晚三叠世随古特提斯的闭合,经印支运动张裂陆缘发生反转,形成印支褶皱造山带。其后,随着新特提斯的俯冲消亡,印度板块与欧亚大陆的碰撞,这一地区与青藏高原一起发生隆升,其东部受龙门山陆内俯冲影响,发育陆内褶皱造山带,最终形成现今的构造格局。因此,松潘-阿坝地区沉积组合类型、盆地构造演化具有多旋回的特点。松潘-阿坝地区总体处于过成熟的早期阶段,进入生成大量甲烷气阶段,具有寻找天然气的前景。从区内已有化探及非地震勘探成果表明,若尔盖坳陷为油气保存条件最好的地区,是松潘-阿坝地区有利的油气勘探区带。更多还原

【Abstract】 Songpan-Aba area has experienced two major extensional-compressional tectonic stages during the regional tectonic evolution. The first stage began with the dismembering of late Proterozoic China ancient land. In Early Paleozoic, the Tianshan-Qilian-Qinling ocean was formed, which separated Yangtze landmass from North China landmass; and passive epicontinental basin was developed on the northern edge of Songpan-Aba area. The Early Paleozoic oceanic basins consumed along with the consumption of the proto-Tethys. Due to the Caledonian subduction, the Yangtze landmass collided with the North China landmass, which finally formed the Caledonian subducting orogenic belt, resulting in the inversion of the passive epicontinental basin. The second stage began in the Late Paleozoic, chasmic troughs and small oceanic crusts between them were developed on the western edge of Yangtze landmass along with the spreading of Paleo-Tethys, resulting in the formation of extensional and fractured continental margin and the development of turbidite sedimentary basin on the western and/or southern edge of Songpan-Aba area. In Late Triassic, the extensional and fractured continental margin was inverted during Indosinian movement along with the closure of the Paleo-Tethys, resulting in the formation of Indosinian folded orogen. Later, this area was uplifted together with Qinghai-Tibet plateau along with the subduction and consumption of Neo-Thetis and collision of Indian plate with Eurasia. Affected by the Longmenshan intracontinental subduction, an intracontinental folded orogen was developed in the eastern part, and finally formed the present tectonic framework. Therefore, the sedimentation types and tectonic evolution of the basins are characterized by their multicyclic features. As a whole, Songpan-Aba area is in the early stage of over-mature and begins to generate large amount of methane, thus it has gas potential. The available geochemical and non-seismic geophysical exploration results show that Norgai depression has the most favorable conditions for hydrocarbon preservation and is a favorable play in Songpan-Aba area.更多还原