三塘湖盆地芦草沟组烃源岩及其古环境

The Source Rock and Its Palaeo-environment of Lucaogou Formation, Permian in Santanghu Basin

三塘湖盆地中二叠统芦草沟组分布于马朗凹陷和条湖凹陷西南部边缘 ,主要由碳酸盐岩和暗色泥岩组成 ,是盆地主力生油岩。碳酸盐岩、伽马蜡烷指数 (GI)、原油碳同位素组成表明芦草沟组沉积于咸水—半咸水古水体环境中 ,其主要沉积中心位于盆地西南边缘东侧 ,呈北西—南东方向延伸 ,与区域构造延伸方向基本一致。芦草沟组时期的原型盆地范围比现在大 ,尤其是原型盆地的西南边界应位于现在边界的更西南部 ,从其碳酸盐岩厚度和伽马蜡烷含量的变化来看 ,三塘湖盆地与相邻的吐哈盆地和准噶尔盆地呈相互独立分隔的状态。

The middle Permian Lucaogou Fm. was distributed within Malang sag and the southwestern part of Tiaohu sag. It was the main source rock composed from carbonate rocks and dark shale. Lucaogou Fm. was deposited in the paleao-environment from saltwater to half-saltwater based on carbonate rocks, gammacerane index (GI) and carbon isotopes of crude oils. Its depositional center, located on the eastern side of the southwest thrust structure belt, extended along the northwest-southeast direction and paralleled to the regional structural range. The prototype basin's scope of Lucaogou Fm. was greater than present. In particular, its southwest boundary should be out of the Lucaogou Fm. basin. Santanghu basin was separated reciprocally with Tu-Ha basin and Junggar basin based on the variations of carbonate rock's thickness and gammacerane index during Lucaogou Fm. sedimentation.