内蒙古雅布赖盆地红柳沟中侏罗统沉积相及沉积环境研究

野外考察发现,雅布赖盆地红柳沟发育一套较完整的中侏罗统扇三角洲沉积地层。其中沉积亚相有扇三角洲平原、扇三角洲前缘及前扇三角洲亚相;沉积微相包括辫状河道、天然堤、决口、沼泽、水下分流河道、水下分流河道间、河口坝、席状砂等沉积微相。从沉积构造特征分析可以看出,河道沉积发育于水动力条件较强的沉积环境,扇三角洲前缘河口坝沉积发育于强与弱水动力条件交替出现的沉积环境,而前扇三角洲则在比较稳定的水动力条件下沉积。对野外6个泥岩样品的微量元素化验结果用蜘蛛图解分析处理,得到样品所含微量元素V、Sr、Rb、B相对富集,而Zr、Cr、Ni相对亏损。通过对该地区样品w（Fe^2＋）/w（Fe^3＋）及气候指数计算表明,当时为弱氧化、半干旱的沉积环境。

Study on Sedimentary Facies and Environment of Middle Jurassic in Hongliugou of Yabulai Basin,Inner Mongolia

Based on the field investigation in Hongliugou of Yabulai Basin,the results indicate that the main sedimentary facies is Jurassic fan delta,which can be divided into three subfacies including fan delta plain,fan delta front and pre-fan delta and six microfacies including braided channel,natural levee,crevasse,marsh,underwater distributary channel,underwater distributary interchannel,mouth bar,sheet sand,and so on.According to the field characteristics of sedimentary structures,the channel deposits developed in the condition of strong hydrodynamic,mouth bar deposits of fan delta front developed in the condition of alternating dynamic of strong and weak,and the pre-fan delta developed in the condition of relatively stable hydrodynamic.According to the analysis of trace elements in six samples of mudstone with spider diagrams,the results show that the contents of V,Sr,Rb,B are relatively high,but Zr,Cr,Ni are relatively low.Calculations of climate index and the ratio of mass factions of Fe^2＋ and Fe^3＋ show that the sedimentary environment was weak oxidation and semi-arid in Middle Jurassic.