扬子地区牛蹄塘组矿物岩石学特征及黄铁矿的环境指示意义

发布时间：2018-04-11 06:39

  本文选题：扬子地区 + 牛蹄塘组　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：本文以扬子地块牛蹄塘组黑色页岩作为研究对象,通过对牛蹄塘组黑色页岩样品进行镜下观察、X射线粉晶衍射(XRD)及黄铁矿硫同位素等测试方法,对扬子地块牛蹄塘组黑色页岩的矿物岩石特征进行了分析研究,并且针对牛蹄塘组黑色页岩中不同成因黄铁矿进行识别与分类,分析了同生黄铁矿对沉积环境的指示意义,并得到了一定的认识。扬子地区下寒武统牛蹄塘组黑色页岩矿物成分主要为以石英为主的硅质矿物和及以伊利石为主的黏土矿物,并含有少量的碳酸盐矿物及黄铁矿。其中以石英为主的硅质矿物含量约为54.6%,黏土矿物含量约为34.8%,TOC约为0.04%~9.93%,平均为2.45%;本文通过在光学显微镜和SEM场发射扫描电镜下对黄铁矿的观察发现,扬子地区下寒武统牛蹄塘组黑色页岩主要含有同生黄铁矿和成岩黄铁矿两种,而只有同生黄铁矿具有沉积环境及对储层的指示意义;扬子地区牛蹄塘组黑色页岩中草莓状黄铁矿为同生草莓状黄铁矿,粒径集中在4~6μm范围,中值为5.15μm且变化范围较窄,指示牛蹄塘组黑色页岩形成于静滞-缺氧水体环境;同生黄铁矿及成岩黄铁矿在晶形、产状、硫同位素值等方面存在显著差异,同生黄铁矿的硫同位素(δ34SV-CDT)平均值明显高于受流体影响成岩黄铁矿,变化范围主要集中在19~25‰,平均为21.60‰,且均为17.4‰的正值。指示牛蹄塘组黑色页岩形成于一种封闭的海洋水体环境;
[Abstract]:In this paper, the black shale of Niutetang formation in Yangzi block was used as the research object, and the X ray powder diffraction (XRD) and pyrite sulfur isotopes were observed under microscope for the black shale samples of Niulitang formation.The mineral and rock characteristics of black shale of Niulitang formation in Yangzi block are analyzed, and the indication significance of syngenic pyrite to sedimentary environment is analyzed according to the identification and classification of different origin pyrite in black shale of Niulitang formation.And got a certain understanding.The black shale minerals of Niutetang formation of Lower Cambrian in Yangzi area are mainly composed of quartz siliceous minerals and Illite clay minerals with a small amount of carbonate minerals and pyrite.Among them, the content of siliceous minerals, mainly quartz, is about 54.6, and the content of clay is about 34.8TOC is about 0.04 and 9.93, with an average of 2.45.The observation of pyrite by optical microscope and SEM field emission scanning electron microscope shows that,There are two kinds of syngenic pyrite and diagenetic pyrite in the black shale of Niulitang formation of Lower Cambrian in Yangzi area, but only syngenic pyrite has sedimentary environment and indicative significance to reservoir.The strawberry pyrite in the black shale of Niulitang formation in Yangzi area is syngenic strawberry pyrite, the diameter of which is concentrated in the range of 4 ~ 6 渭 m, the median value is 5.15 渭 m and the range of variation is relatively narrow, indicating that the black shale of Niulitang formation is formed in the stagnant and anoxic water environment.There are significant differences between syngenic pyrite and diagenetic pyrite in crystal shape, occurrence and sulfur isotope value. The average value of sulfur isotope (未 34SV-CDT) of syngenic pyrite is obviously higher than that of fluid affected diagenetic pyrite, and the range of variation is mainly 1925 鈥，

本文编号：1734842