摘要
为深入探讨贵州黔南地区早石炭世打屋坝组黑色岩系的沉积环境与物源分析,笔者选取了贵州惠水王佑地区早石炭世打屋坝组黑色岩系进行系统采样和稀土元素地球化学分析,探讨该区域黑色岩系的沉积环境变化特征,为下一步页岩气勘探提供参考。分析结果表明,研究区域的稀土元素总量ΣREE为(100.52~627.32)×10^(-6),平均值为191.20×10^(-6),比北美页岩稀土总量(200.21×10^(-6))略低。通过LREE/HREE,δCe,δEu等相关参数显示,研究区域的黑色岩系经北美页岩标准化后曲线呈平坦状,表现为轻稀土富集,重稀土相对亏损;研究区域样品的δEu值为0.86~1.11,平均值为0.97,δCe值为0.92~1.12,平均值为1.03,异常表现不明显,结合野外岩性特征变化,可推断研究区域的沉积环境表现为弱氧化-弱还原环境,属于台地边缘斜坡-浅海陆棚相;通过w(ΣREE)-w(La)/w(Yb)图解可知,研究区域的物源属于上地壳花岗岩与沉积岩的混合物;此外,结合研究区域样品的TOC含量与黄铁矿的富集程度可知,贵州惠水王佑地区早石炭世打屋坝组黑色岩系具有良好的生烃潜力。
In order to discuss sedimentary environment and source analysis of black rock series from the Early Carboniferous Dawuba Formation in southern Guizhou furtherly,the authors selected the black rock series of Wangyou Huishui area from the Early Carboniferous Dawuba Formation in southern Guizhou for sampling and analyzing rare earth element geochemistry,explored the regional sedimentary environment of black rock series characteristic and provided information for further shale gas exploration. The results of research showed that the ΣREE values for the early Carboniferous black rock series varied from 100. 52 × 10-6to 627. 32 × 10-6,with an average of 191. 20 × 10-6,which is slightly lower than the 200. 21 × 10-6for the North American Shale Composites. The geochemical parameters such as LREE/HREE,δCe and δEu ratios indicated that for the black rock series from the studied area after standardization of North American shale the curve showed the flat shape. It showed the enrichment of LREE and the depletion of HREE. The δEu values of the studied area samples ranged from 0. 86 to 1. 11,with an average of0. 97. The δCe values ranged from 0. 92 to 1. 12,with an average of 0. 97,and the abnormal performance was not obvious. In combination with the changes of lithologic characteristics in the field,it can be concluded that the sedimentary environment of the studied area changed from weak oxidation to reduction environment,which belonged to the platform edge-shallow shelf facies. By w（ ΣREE）-w（ La）/w（ Yb） diagrams,the material source of the area is a mixture of crustal granites and sedimentary rocks. On the basis of the TOC content and degree of enrichment of pyrite,it implied that the black rock series of Huishui Wangyou have good hydrocarbon generation potential for the Early Carboniferous Dawuba Formation in southern,Guizhou.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2017年第5期620-631,共12页
Journal of the Chinese Society of Rare Earths
基金
中国地质调查局页岩气调查项目(DD20160182-05)
贵州省重点学科地质资源与地质工程建设项目(黔学位合字ZDXK[2015]20)资助
关键词
黔南惠水
打屋坝组
黑色岩系
稀土元素
沉积环境
Huishui in southern Guizhou
Dawuba Formation
black rock series
REE
sedimentary environment
