准噶尔盆地构造演化与油气成藏特征

对准噶尔盆地构造特征、地层分布和地层不整合等特征进行的研究结果表明 ,该盆地内经历了裂陷盆地、碰撞前陆盆地、陆内坳陷盆地和陆内俯冲前陆盆地等 4个演化阶段。裂陷盆地控制了石炭系烃源岩 ,使其沿裂陷槽分布 ;碰撞前陆盆地将二叠系烃源岩局限于玛湖、昌吉、克拉美丽山等山前坳陷内 ;陆内坳陷期从三叠纪一直持续到古近纪末 ,盆地内泥岩和煤岩广泛分布 ;陆内俯冲前陆盆地发育在南缘西部。因而 ,古、新近系烃源岩主要分布在安集海呼图壁一带。烃源岩演化和油源对比表明 ,盆地内有 3次成藏期 ,分别为印支期 (T3 )、燕山期 (J3 )和喜山期(E2 ) ,形成了石炭系、二叠系、侏罗系和古近系 4个复合含油气系统。根据构造特征和成藏条件的差异性 ,在盆地内可划分出西北部、西部、南部、东部和腹部 5个油气聚集区带。准噶尔盆地的成藏模式主要有逆冲断阶不整合单向充注、压扭背斜双向充注、断隆带双向充注、披覆背斜单向充注、逆冲背斜带单向充注和斜坡带单向充注 6种类型。

Structural evolution and pool-forming in Junggar Basin

The study of tectonic characters, strata distribution and strata unconformity analyses showed that Junggar Basin underwent four evolution periods of aulacogen basin, collision foreland basin, inland depression basin and inland subduction foreland basin. The aulacogen basin controlled the Carboniferous source rock distributed along rift valley. The collision foreland basin controlled the Permian source rock limited in Mahu, Changji and Kelameili piedmont depressions. The term of inland depression was continuous from the Triassic to the end of the lower Tertiary. During this term, mudstone and coal rock were widespread in Junggar Basin. The inland subduction basin was developed in the west of southern basin. The Tertiary source rock was mainly distributed in the Anjihai and Hutubi areas. The correlation of source rock evolution and oil origin showed that there were three times of pool-forming, namely Indosinian epoch (T_3), Yanshan epoch(J_3) and Xishan epoch(E_2). During this term, four composite petroleum systems, including Carboniferous, Permian, Jurassic and the lower Tertiary composite petroleum systems, were developed. According to the difference of tectonic characters and pool-forming condition, oil and gas accumulation area can be divided into five zones of north-west, west, south, east and central areas in Junggar Basin, there are six types of pool-forming models including subduction fault terrace-unconformity single charge, compressive wrench anticline double charge, fault-uplift zone double charge, drape anticline single charge, thrust anticline zone single charge and slope zone single charge.