三江盆地南部猴石沟组砂岩地球化学特征及地质意义  

GEOCHEMICAL CHARACTERISTICS OF THE SANDSTONE FROM HOUSHIGOU FORMATION IN SOUTHERN SANJIANG BASIN:Geological Implication

作　　者：李研 LI Yan(No.240 Institute of Nuclear Industry,Shenyang 110000,China)

机构地区：[1]核工业240研究所,辽宁沈阳110000

出　　处：《地质与资源》2024年第3期315-322,共8页Geology and Resources

基　　金：中国核工业地质局项目“吉林省辽源-黑龙江省富锦地区砂岩型铀矿资源调查评价”(202225)。

摘　　要：三江盆地白垩系猴石沟组是主要的铀矿含矿层,发育大面积灰色、浅黄色含砾中—细砂岩.本文以松木河凹陷猴石沟组砂岩为研究对象,通过详细的岩石学、地球化学等特征探讨了猴石沟组的物源区成分、源区风化强度及构造背景.结果表明,猴石沟组砂岩以长石和岩屑砂岩为主,主量元素SiO_(2)含量在58.91%~71.51%之间,全碱含量4.59%~10.05%,铝含量12.87%~16.12%.稀土元素总量100.72×10^(-6)~171.34×10^(-6),平均为134.532×10^(-6),Eu负异常相对明显(δEu=0.27~0.84),说明岩石来源于上地壳.元素地球化学特征表明,猴石沟组砂岩CIA=13.13~45.25,ICV=0.74~1.02,PIA=53.08~67.90,整体说明猴石沟组沉积时期为干旱—半干旱环境,源区经历了弱风化作用.Sr/Ba大多数小于1,相当B含量大多数亦小于200×10^(-6),SiO_(2)/Al_(2)O_(3)平均为4.35,表明猴石沟组沉积时期为低盐度环境.砂岩具有活动大陆边缘地球化学属性,结合区域演化史,认为其物源区应为佳木斯隆起地区发育的长英质岩石.The Cretaceous Houshigou Formation in Sanjiang Basin is the main ore-bearing layer of uranium deposit,developed with a large area of grey and light yellow gravel fine-medium sandstone.Taking the sandstone of Houshigou Formation in Songmuhe sag as the study object,the paper discusses the provenance composition,weathering intensity and tectonic setting of Houshigou Formation on the basis of detailed petrological and geochemical characteristics.The results show that the formation is mainly feldspar and lithic sandstone,with the major element SiO_(2) content of 58.91%-71.51%,total alkali content of 4.59%-10.05%,and Al content of 12.87%-16.12%.The total content of rare earth element(∑REE)is 100.72×10^(-6)-171.34×10^(-6),averagely 134.532×10^(-6),with obvious negative Eu anomaly(δEu=0.27-0.84),indicating that the rock originates from the upper crust.The element geochemical characteristics reveal that CIA is 13.13-45.25,ICV 0.74-1.02 and PIA 53.08-67.90,indicating that the sedimentary period of Houshigou Formation was in arid-semi arid environment,and the source area experienced weak weathering.The Sr/Ba ratio is mostly less than 1,the equivalent B content mostly less than 200×10^(-6) and the SiO_(2)/Al_(2)O_(3) ratio averagely 4.35,indicating that the sedimentary period of Houshigou Formation was in low salinity environment.The sandstone has the geochemical properties of active continental margin.Combined with the regional evolution history,it is believed that the source area should be the felsic rock developed in Jiamusi uplift.

关 键 词：猴石沟组 铀矿 砂岩 松木河凹陷 地球化学 三江盆地 

分 类 号：P619.14[天文地球—矿床学]