准南西段侏罗系——白垩系物源特征及沉积背景

准噶尔盆地南缘西段侏罗系—白垩系储层油气勘探潜力巨大，但目前有关其物源条件及沉积背景认识极为有限，严重制约了后续储层的有效预测和勘探。据此，通过对侏罗系—白垩系储层碎屑矿物及砾石成分特征、重矿物类型及组合特征、古水流特征、地层岩性比例特征等进行深入对比分析，并在此基础上结合区域构造演化对各地层沉积物源体系及其演化进行详细探讨。研究结果表明:侏罗系—白垩系储层物源主体受控于北部和南部再循环沉积岩系山体，但仍受北部扎伊尔山和南部中天山结晶变质岩系山体源区的影响，其影响程度自早侏罗世到早白垩世逐渐降低。下组合沉积期南部、北部物源同时存在，且研究区存在混源特征，但不存在统一且稳定的沉积中心。早侏罗世沉积物源背景相对稳定，原始沉积边界距现今最远；自中侏罗世开始受控于车莫古隆起演化影响，北部物源得以加强，同时地层发育不均衡并存在剥蚀现象；自晚侏罗世开始直至早白垩世，周缘沉积岩系山体隆升范围和幅度不断加大，并阻隔结晶变质岩系山体供源路径，沉积边界也随之逐渐萎缩，但这一时期北部物源可为优势物源，且研究区整体处于“填平补齐”状态，即齐古组沉积期可存在沟谷—残丘地貌特征，而下白垩统清水河组沉积前研究区整体呈准平原化状态。

Provenance and Depositional Setting of the Jurassic-Cretaceous Within the Western Part of the Southern Junggar Basin

The lower assemblage reservoirs within the western part of the southern Junggar Basin have great hydrocarbon exploration potential. However， the current understanding of the provenance condition and sedimentary background of these reservoirs is extremely limited， which severely restricts the subsequent effective prediction and exploration processes. Therefore， based on the detailed analysis of sandstone detrital mineral composition and conglomerate gravel content， heavy mineral type and assemblage， paleocurrent direction， and strata lithology ratio with regional tectonic evolution research findings， this study fully discusses the provenance and sedimentary system characteristics and evolution histories of different formations in the lower assemblage. The research results show that the main provenance of the lower assemblage reservoir is controlled by the northern and southern recirculating sedimentary rock mountains， but it can be still affected by the crystalline metamorphic parent rock of the Zaire Mountains in the north and the central Tianshan Mountains in the south. However， the affects gradually decreased from the Early Jurassic to the Cretaceous. In particular， the southern and northern provenances existed at the same time； thus， the study area shows mixed provenance characteristics， with no unified and stable depocenter. The sedimentary background during the Early Jurassic was relatively stable， and the original sedimentary boundary may show the farthest distance away from the present basin boundary. During the Middle Jurassic， controlled by the evolution of the Chemo paleo-uplift， the northern provenance was strengthened， with uneven stratigraphic distribution and occurrence of denudation. However， from the Late Jurassic to the Early Cretaceous， the uplift range and amplitude of the peripheral sedimentary rock mountains continuously increased and blocked the supply path of the crystalline metamorphic rock mountains. The sedimentary boundary gradually shrank， and the northern provenance became dominant. Moreover， the study area may show valley-monadnock landforms before the deposition of the Qigu Formation， while peneplain characteristics are evident before the deposition of the Qingshuihe Formation.