红色泥岩层系地球化学特征及物源分析——以松辽盆地东南隆起区上白垩统姚家组为例

对松辽盆地东南隆起区姚家组地层进行系统的地球化学分析,结果表明:本区细碎屑岩中含有较多的稳定组分。通过对微量元素PAAS标准化及稀土元素标准化曲线配分模式研究,研究区内姚家组地层应来自同一物源区。CIA值及Th/U值表明源区经历了中等的风化作用;Th/Sc和Zr/Sc比值变化范围小,地球化学特征基本受源岩控制,物源区岩石未经过沉积再搬运。根据源岩构造背景判别图解,并结合前人的研究成果认为:姚家组地层的母岩主要为花岗岩(海西期和燕山期),并有少量燕山期中酸性喷出岩;源岩来自大陆边缘,为大陆岛弧火山岩系。通过Sr/Cu,Ni/Co,V/Cr,U/Th等比值综合分析,姚家组沉积时为干热气候,水体富氧,因此造成姚家组厚层的红色泥岩沉积。

Geochemical characteristics and sediment provenance analysis of red mudstone formation: a case study of Upper Cretaceous Yaojia Formation of southeastern uplift area in Songliao Basin

Samples of Yaojia Formation of southeastern uplift area in Songlioa Basin were systematically ana- lyzed by the authors，and the geochemical data indicate that fine grained detrital rocks in this area mostly contain stable components． The PAAS- standardized distribution curves of trace elements and ＲEEs suggest that the material sources of Yaojia Formation in the studied area mainly came from one type of provenance． The CIA and the Th/U ratio suggest that provenances had underwent moderate weathering processes． The slight changes of Th/Sc and Zr/ Sc ratios illustrate that there were no second transportation of mudstones and geochemical features were mainly con- trolled by source rocks． On the basis of discrimination diagrams of tectonic setting of the source rocks and previous research material of former studies，the authors conclude that the provenance of the Yaojia Formation in the studied area was mainly Hercynian and Yanshannian granites，which also involves some Yanshannian intermediate- acid ex- trusive rocks． Source rocks were formed in the continental margin orogenic belt and belonged to continental island arc volcanic series． Comprehensive analysis on ratios of Sr/Cu， Ni/Co， V/Cr and U/Th shows the arid climate and shallow water with oxygen enrichment of Yaojia Formation deposition，which results in the red color．