松辽盆地南部中央凹陷区姚家组砂岩地球化学特征及沉积物源

沉积物源对研究含铀砂体展布和含铀流体运移通道均具有指示意义.以松辽盆地南部中央凹陷区姚家组为研究对象，在砂岩样品系统地球化学测试和收集邻区钱家店铀矿研究成果的基础上，讨论研究区姚家组砂岩的地球化学、形成环境和沉积物源并与钱家店地区对比.研究表明，姚家组砂岩碎屑相对富含硅和铝元素，岩石类型主要为岩屑砂岩和长石砂岩；稀土元素含量160.12×10^-6~253.74×10^-6，表现为轻稀土（La、Ce、Pr等）富集、重稀土（Ho、Er、Tm、Yb、Lu）平坦、中度铕（Eu）负异常；主量、微量和稀土元素揭示砂岩形成于干旱-半干旱气候，化学蚀变程度不高，物源构造背景为主动大陆边缘.结合区域构造背景，认为研究区与钱家店地区物源成分相似而物源的方向不同，研究区姚家组砂岩碎屑母质源自东北或西南物源，源岩类型主要为花岗闪长岩和花岗岩.

GEOCHEMISTRY AND SEDIMENT PROVENANCE OF SANDSTONE FROM YAOJIA FORMATION IN CENTRAL DEPRESSION,SOUTHERN SONGLIAO BASIN

The sediment provenance is of indicative significance to study the distribution of uranium sand body and migration channel of uranium fluid. Taking the Yaojia Formation in Central Depression of southern Songliao Basin as object, based on the systematic geochemical testing of sandstone samples and collected data of neighboring Qianjiadian uranium deposit, the paper discusses the geochemistry, formation environment and sediment provenance of sandstone of Yaojia Formation and compares with those in Qianjiadian area. The results show that the sandstone detrital of Yaojia Formation is relatively rich in Si and Al, with the main rock types of lithic sandstone and arkose. The REE content is 160.12×10^-6-253.74×10^-6, characterized by enriched LREEs (La, Ce, Pr, etc.), flat HREEs (Ho, Er, Tm, Yb and Lu) and moderate negative Eu anomaly. The analysis of major, trace and rare earth elements reveal that the sandstone was formed in arid-semiarid climate, without high degree of chemical alteration, and the tectonic setting of provenance is active continental margin. Combined with the regional tectonic background, it is considered that the provenance component of the study area is similar to that of Qianjiadian area, but the source directions are different. The parent material for sandstone detrital of Yaojia Formation in the study area is derived from the northeast or southwest provenance, with the main source rocks of granodiorite and granite.