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现代地质 ›› 2021, Vol. 35 ›› Issue (02): 568-578.DOI: 10.19657/j.geoscience.1000-8527.2021.040

• 岩石学 • 上一篇    下一篇

松辽盆地北部上二叠统林西组古生物年代学、地球化学特征及地质意义

张海华(), 李晓海(), 张健, 郑月娟, 陈树旺, 张德军, 苏飞, 卞雄飞, 孙雷   

  1. 中国地质调查局沈阳地质调查中心,辽宁 沈阳 110034
  • 收稿日期:2020-11-30 修回日期:2021-02-20 出版日期:2021-04-25 发布日期:2021-05-25
  • 通讯作者: 李晓海
  • 作者简介:李晓海,男,硕士,1982年出生,高级工程师,构造地质专业,主要从事油气基础地质调查研究。Email: 641426683@qq.com
    张海华,男,硕士研究生,1986年出生,构造地质专业,主要从事岩石学、大地构造学研究。Email: zhanghaihua311@163.com
  • 基金资助:
    中国地质调查局项目(DD20160163);中国地质调查局项目(DD20190097)

Paleochronology, Geochemical Characteristics, and Geological Significance of the Upper Permian Linxi Formation in the Northern Songliao Basin

ZHANG Haihua(), LI Xiaohai(), ZHANG Jian, ZHENG Yuejuan, CHEN Shuwang, ZHANG Dejun, SU Fei, BIAN Xiongfei, SUN Lei   

  1. Shenyang Center of Geological Survey, China Geological Survey, Shenyang, Liaoning 110034, China
  • Received:2020-11-30 Revised:2021-02-20 Online:2021-04-25 Published:2021-05-25
  • Contact: LI Xiaohai

摘要:

对松辽盆地北部地区黑富地1井钻遇的上二叠统林西组碎屑岩样品进行微体化石以及主量元素、微量元素和稀土元素测试分析,进而探讨该区林西组时代、地球化学特征、沉积环境及构造背景。获得的Protohaploxypinus fertilis-Piceaepollenites opimus-Alisporites communis孢粉化石组合表明地层时代为晚二叠世。样品主量元素平均质量分数:SiO2为60.41%,CaO为3.65%,Al2O3为16.36%,K2O为2.69%, Na2O为3.25%, K2O/Na2O值介于0.40~7.01之间,A12O3/(CaO+Na2O)值介于0.92~6.89之间。稀土元素ΣREE为63.20×10-6~208.05×10-6,平均值147.56×10-6;δEu介于0.56~1.34之间,平均为0.73,绝大部分表现为Eu负异常;δCe介于0.90~0.98之间,为弱的Ce负异常;呈现LREE富集、HREE亏损。微量元素以亏损Nb、Ta、Sr和相对较富集Rb、Ba、La、Sm、Pb、Nd为特征。碎屑岩元素分析和物源La/Th-Hf、TiO2-Ni等判别图表明,林西组具有多样性沉积物源,其碎屑岩沉积物主要源于长英质物质,少量来自基性岩。样品稀土元素标准化配分模式图、微量元素标准化蛛网图、K2O/Na2O-SiO2、构造背景判别函数(F1-F2)等分析结果及地球化学参数对比表明,松辽盆地北部黑富地1井林西组物源区构造背景主要为活动大陆边缘和大陆岛弧,推测为形成于靠近大陆岛弧的活动大陆边缘构造背景,所形成的沉积环境应为海陆过渡相逐渐转变为陆相。

关键词: 松辽盆地, 林西组, 孢粉, 地球化学, 构造背景

Abstract:

The paleontological fossils, major and trace elements (including rare earth elements (REEs)) of the Upper Permian Linxi Formation (Fm.) clastic rocks in well Heifudi 1 in the northern Songliao Basin were analyzed, in order to explore the age, geochemical characteristics, sedimentary environment, and tectonic background of the Linxi Formation. The Protohaploxypinus fertilis, Piceaepollenites opimus, and Alisporites communis palynological fossil assemblages obtained in this study indicate that the stratigraphic age is Late Permian. The average content of major elements is SiO2=60.41%, CaO=3.65%, Al2O3=16.36%, K2O=2.69%, Na2O=3.25%, K2O/Na2O=0.40-7.01, and A12O3/(CaO+Na2O)=0.92-6.89. The total REE (ΣREE) contents are of 63.20×10-6-208.05×10-6(average 147.56×10-6), with mainly negative Eu anomalies (δEu) of 0.56-1.34 (average 0.73) and weakly-negative Ce anomalies (δCe=0.90-0.98). The clastic rocks are characterized by LREE enrichments and HREE depletions. The trace element contents are characterized by depletions in Nb, Ta, and Sr, and enrichments in Rb, Ba, La, Sm, Pb, and Nd. Geochemical features of the clastic rocks and the discrimination diagrams of La/Th-Hf and TiO2- Ni show that the Linxi Formation has diverse sediment sources, mainly from upper-crustal felsic rocks and minor from mafic rocks. The primitive-mantle normalized multi-element and chondrite-normalized REE diagrams, K2O/Na2O-SiO2 plot, together with tectonic discrimination functions (F1, F2) and geochemical parameters indicate that the northern Songliao basin provenance source region was largely in an active continental margin and continental island arc setting, whilst the sedimentary facies was transitioned from marine-terrestrial to terrestrial.

Key words: Songliao Basin, Linxi Formation, spores and pollen, geochemistry, tectonic setting

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