摘要
为明确顺北地区中下奥陶统硅质岩特征及其成因。在岩石学特征研究基础上,对不同产状硅质岩样品进行稀土元素和微量元素测试分析,结合硅氧同位素测试结果开展顺北地区中下奥陶统硅质岩特征及成因研究。研究结果表明:硅质以灰黑色条带状、团块状和灰白色条带状分布于灰岩之间,与基质灰岩粒屑镶嵌发育。岩心断面局部可见贝壳类和介壳类生物碎屑。硅质岩样品稀土元素含量很低,平均仅0.3μg/g,整体表现为轻稀土富集、重稀土亏损,两者分异明显且具有明显正Eu和正Ce异常,指示热液流体对硅质岩形成具有重要影响,且硅质岩颗粒Ni/Co值为6.53~55.45,平均值23.7,表明硅质岩主要形成于相对还原的成岩环境中。不同产状硅质岩δ30 Si‰值分布范围0.6‰~2.74‰,平均1.74‰,指示交代成因为主。综合分析认为,顺北地区中下奥陶统硅质主要来源于深部富硅流体,流体在颗粒灰岩发育相带交代围岩形成硅质岩,但改造作用使原岩颗粒孔隙降低,整体表现为破坏性成岩作用。
In order to clarify the characteristics and genesis of middle lower Ordovician siliceous rocks in Shunbei Area.Based on the study of petrological characteristics,rare earth elements and trace elements of siliceous rocks with different occurrence were tested and analyzed,and the characteristics and genesis of middle and lower Ordovician siliceous rocks in Shunbei area were studied combined with the results of silicon oxygen isotope test.The results show that the siliceous rocks are distributed among the limestones in gray black banded,agglomerated and gray white banded forms,and are embedded with the matrix limestone particles.Shellfish and crustacean bioclasts can be seen locally in the core section.The REE content of siliceous rock samples is very low,with an average of only 0.3%μg/g and Ni/CO ratio of siliceous rocks is 6.53~55.45,with an average of 23.7,indicating that the siliceous rocks were mainly formed in a relatively reduced diagenetic environment.Siliceous rocks with different occurrence.The distribution ofδ30Si‰values ranged from 0.6‰to 2.74‰,with an average of 1.74‰,indicating that metasomatism is the main cause.Comprehensive analysis shows that the middle and lower Ordovician siliceous rocks in Shunbei area are mainly derived from deep silicon rich fluids,which metasomatize the surrounding rocks in the developed facies zone of granular limestone to form siliceous rocks,but the transformation reduces the grain pores of the original rocks,showing destructive diagenesis as a whole.
作者
王昱翔
顾忆
傅强
王斌
于晓东
WANG Yu-xiang;GU Yi;FU Qiang;WANG Bin;YU Xiao-dong(SINOPEC Geophysical Research Institute, Nanjing 210014, China;Institute of Petroleum Geology, Research Institute of Petroleum Exploration and Development of SINOPEC, Wuxi 214126, China;School of Ocean and Earth Science, Tongji University, Shanghai 200092, China)
出处
《科学技术与工程》
北大核心
2021年第27期11506-11513,共8页
Science Technology and Engineering
基金
中国石油化工股份有限公司科技开发部项目(P15115)。
关键词
稀土元素
微量元素
硅氧同位素
硅质岩
顺北地区
塔里木盆地
rare earth element
trace element
silicon and oxygen isotopes
silicate
Shunbei Area
Tarim Basin
