摘要
基于东营凹陷南坡沙河街组四段砂岩的某些常量元素和微量元素(包括稀土元素)含量的变化规律,研究了该地区砂岩的地球化学特征。本地区沙河街组四段砂岩类型以岩屑长石砂岩和长石岩屑砂岩为主,部分砂岩为岩屑砂岩和长石砂岩。A-CN-K三角图解反映了砂岩的母岩中斜长石含量要高于钾长石含量,主要在花岗闪长岩和花岗岩(含相应的片麻岩)之间变化。砂岩在风化过程中受到了钾的交代作用。化学风化作用指标(CIW)和化学蚀变作用指标(CIA)反映了该地区砂岩受到了强烈的风化作用,尤以纯梁地区为强。化学组份变化指标(ICV)反映了有些砂岩中含有第一次旋回沉积物。微量元素比值(La/Yb)N、(La/Lu)N等也反映了该地区砂岩来源于花岗闪长岩和花岗岩的混合物。
Based on some changing laws of invariable primary element and trace element （including REE） contents in Wangjiagang, Guangli and Chunliang areas, the sedimento-geochemical features of sandstones from the Fourth Member, Shahejie Formation in the Southern Slope of Dongying Sag were studied in this paper. The majority of the sandstones was feldspathic litharenite and lithic arkose, and the subordinate parts were lithic sandstones and feldspar sandstones. The A-CN-K diagram indicated that the average plagioclase content was higher ＇than the potassium feldspar content in the provenance, which varied from granodioritic rocks to granitic ones （including the relevant gneisses）. The sandstones underwent K-metasomatism during weathering processes. The parameters of chemical index of weathering （CIW） and the chemical index of alteration （CIA） suggested that the sandstones in the area might be weatheringed intensely, especially in the Chunliang area. The index of compositional variability （ICV） showed that there might be some first cycle material in the sandstones. In addition, the trace el- ement ratios, such as （La/Yb） N and （La/Lu） N, suggested further that the provenance for the sandstones in the Southern Slope of Dongying Sag should be a mixed one of granodioritic and granitic （including relevant gneissic） rocks.
出处
《地质科学》
CAS
CSCD
北大核心
2007年第2期303-318,共16页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
中国石油化工股份有限公司胜利油田有限公司"十五"科技攻关项目(东营凹陷南坡沙四段沉积相研究及有利目标预测)的部分成果
关键词
砂岩
沉积地球化学
物源区
沙河街组四段
东营凹陷南坡
Sandstones, Sedimento-geochemical features, Provenance, The Fourth Member of Shahejie Formation, The Southern Slope of Dongying Sag
