准噶尔盆地二叠系源- 汇系统与古地理重建

源- 汇系统是目前国内外地球科学领域的研究热点，对于含油气盆地古地理重建以及源储预测评价有着重要的指导作用。本文以准噶尔盆地二叠系为研究对象，通过基于盆地地质大剖面的构造- 层序特征分析、定年数据的物源体系演化分析和沉积过程约束的正演模拟等方法，深化了对准噶尔盆地二叠纪古地理格局的认识，探讨了二叠纪源- 汇系统演化特征与二叠系源储分布规律。早二叠世为盆地断陷发育期，以石炭系为主物源，除东南部发育海相- 海陆过渡相沉积外，总体以近物源扇三角洲- 湖相沉积体系为主，多断陷的沉积格局控制了玛湖等凹陷优质烃源岩的分布，与火山岩相关的扇三角洲前缘砂体与混积云质岩构成有利储集体；中二叠世为盆地断- 拗转换期，物源年龄开始趋于复杂，沉积中心、沉降中心较早二叠世明显向盆内迁移，早期断陷趋于连通，盆地西部仍以近物源的扇三角洲群- 湖相沉积体系为主，东南部则转换为远物源三角洲群- 湖盆沉积体系，在盆地中部发育连片分布的规模烃源岩，可与同期（扇）三角洲前缘形成良好的源储组合；晚二叠世进入盆地拗陷发育期，物源供给范围更广，物源年龄进一步复杂化，大型浅水湖盆发育远物源为主的退覆型河流- 三角洲沉积体系，为盆地规模油气成藏奠定了储层基础。

Source- to- sink system and palaeogeographic reconstruction of Permian in the Junggar basin, northwestern China

Source- to- sink system is a hot topic in geosciences, which has an important guiding role in the paleogeographic reconstruction of hydrocarbon- bearing basins and in the prediction and evaluation of source and reservoir of hydrocarbon resources. This study takes the Permian in Junggar basin as an example to analyze the stratigraphic and sedimentary pattern in basin- scale geological sections to investigate the evolution of the provenance system based on the chronostratigraphy, and to set up stratigraphic forward models based on sedimentary constraints. Finally, it explores the evolution and source- reservoir distribution of the source- to- sink system. In the Early Permian, which belonged to faulted basin, Carboniferous of the basin s periphery provided the majority of sediments. Fan delta to lacustrine sedimentation with nearby provenance is dominant in most regions, while marine and continental- marine transition sedimentation developed in the southeastern region. The depositional pattern influenced by multiple faults controlled the distribution of high- quality hydrocarbon source rocks in the Mahu and other depressions, and the sand bodies in delta front and dolomite associated with volcanic rocks constituted favorable reservoirs. In the Middle Permian, which belonged to the transition period from faulted basin to depression, the dating results shows that provenance range tended to be wide and complex. The sedimentation center and subsidence center obviously migrated to the inner basin, and the early- formed faulted sags tended to be connected. The western part of the basin is still dominated by the fan deltas to lacustrine sedimentation system with nearby provenance, while the southeastern part converted to fan deltas to lacustrine sedimentation with distal provenance. The large- scale hydrocarbon source rocks with high connectivity in the central basin can form good source- reservoir association with the delta front formed during this period. In the Late Permian, which belonged to depression, provenance range tended to wider or more complex. Large shallow lake allowed the development of regressive river- delta systems with distal provenance. They provided the reservoir for the basin- scale stratigraphic reservoirs.