敦煌盆地五墩凹陷中间沟组一段物源体系

为明确敦煌盆地五墩凹陷中间沟组一段物源体系及展布,以岩矿与主量元素分析为基础,结合水动力条件、地震剖面反射特征和古地貌分析,研究砂体的发育程度、物源方向与搬运通道,探讨五墩凹陷侏罗系中间沟组不同井区的沉积物来源。研究结果表明：XC1与D2井具有同源性,岩屑类型以变质岩岩屑为主,D1井物源表现出一定差异性,岩屑类型以岩浆岩岩屑为主,主量元素分析结果与岩屑类型分析结果相一致；XC1、D2井主要为近源扇三角洲沉积,D1井主要为远源辫状河三角洲沉积；XC1和D2井区主要接受南部三危山隆起物源区的沉积物供给,D1井区主要接受北部北山物源区的沉积物供给。重新落实的物源体系展布对于研究区砂体展布规律具有重要的指导意义。

Provenance system within the 1st member of Zhongjiangou formation in Wudun Sag of Dunhuang Basin

Based on the analysis of the rock cuttings types and the major elements, and combined with the hydrodynamic conditions, seismic reflection characteristics and the sedimentary palaeogeomorphology, the provenance attribution of different well and distribution are implemented. The results show that well XC1 and well D2 are homologous with the metamorphic rock cuttings mainly, while well D1 shows certain difference with the magmatic rock cuttings mainly. The results of major element analysis are consistent with the results of rock cuttings type analysis. The hydrodynamic condition analysis shows that well XC1 and well D2 are mainly near source fan delta deposits, while well D1 is mainly far source braided river delta deposits. Combined with the analysis of seismic in-phase axial reflection characteristics and sedimentary paleogeomorphic characteristics, XC1 and D2 well block are mainly received the sediment supply from the provenance area of Sanweishan uplift in the south, and D1 well block are mainly received the sediment supply from the provenance area of Beishan in the north. The re-implemented distribution of provenance system is of great significance for the distribution of sand bodies in the study area.