塔里木盆地北部上震旦统葡萄状白云岩的发现及成因探讨
发布时间：2019-06-19 06:59
【摘要】："皮壳—葡萄状"白云岩是一种非常特殊结构的白云岩。文中报道了塔里木盆地西北缘东二沟及塔北星火101井上震旦统奇格布拉克组中皮壳—葡萄状白云岩特征,并对其成因进行了探讨。皮壳状—葡萄状白云石中发育明、暗纤状白云石或纹层条带的含少量细晶的纤状—细粒状白云石以及肾状和葡萄状粉细晶白云石;由球形、杆形、孢子形等蓝细菌构成泡沫状结构;明暗、环带状橙红色光或中等橙红色光、核部发光较暗或不发光;与基质白云石相比,葡萄—皮壳状白云石δ~(13)C_(PDB)相似;但δ~(18)O_(PDB)正偏,87Sr/86Sr相对高(0.70887~0.70939)、但与震旦纪海水(0.7087~0.7094)相似,从皮壳边缘、暗色(蓝细菌)至核部,微区δ~(18)O_(PDB)、δ~(13)C_(PDB)显示了环带内变化较小、环带外的强烈负漂移;云化程度的增加,δ~(18)O_(PDB)、δ~(13)C_(PDB)负偏明显,~(87)Sr/~(86)Sr增加。皮壳—葡萄状白云岩中Al_2O_3、Fe_2O_3、MnO、LREE/HREE值均低于基质泥粉晶云岩对应值、稀土总量介于基质与粉细晶云岩之间,而Na_2O+K_2O、P_2O_5、Sr、Hg、Cu、Sr/Ba、Sr/Mn、δCe值均高于基质泥粉晶云岩对应值;且随着云化程度的提高,总体呈现出Mn含量增加,Al_2O_3、Fe_2O_3、Na_2O+K_2O、P_2O_5、Sr/Ba、Fe/Mn等值递减的趋势;由此判断皮壳状—葡萄状白云石可能是弱还原、保存较好的海水中形成,或在成岩早期或浅埋藏孔隙海水为主的流体中形成、部分经历了较强的大气水作用改造。
[Abstract]:Crust-grape dolomite is a very special structure of dolomite. In this paper, the characteristics of crust-grape dolomite in the Sigebrak formation of the Sinian formation in the Dongergou and Tabei Xinghuo 101 wells in the northwest margin of the Tarim Basin are reported, and the genesis of the dolomite is discussed. In shell-grape dolomite, there are a small amount of fine-grain fine-fine dolomite and kidney-shaped and grape-shaped fine-grain dolomite, which is composed of spherical, rod-shaped, spore-shaped and other blue bacteria, and dark, annular orange-red light or medium orange-red light, and the nucleus is dark or not luminous. Compared with the matrix dolomite, grape-shell dolomite 未 ~ (13) C _ (PDB) is similar. However, 未 ~ (18) O _ (PDB) is positive, 87Sr/86Sr is relatively high (0.70887 鈮，
本文编号：2502186
[Abstract]:Crust-grape dolomite is a very special structure of dolomite. In this paper, the characteristics of crust-grape dolomite in the Sigebrak formation of the Sinian formation in the Dongergou and Tabei Xinghuo 101 wells in the northwest margin of the Tarim Basin are reported, and the genesis of the dolomite is discussed. In shell-grape dolomite, there are a small amount of fine-grain fine-fine dolomite and kidney-shaped and grape-shaped fine-grain dolomite, which is composed of spherical, rod-shaped, spore-shaped and other blue bacteria, and dark, annular orange-red light or medium orange-red light, and the nucleus is dark or not luminous. Compared with the matrix dolomite, grape-shell dolomite 未 ~ (13) C _ (PDB) is similar. However, 未 ~ (18) O _ (PDB) is positive, 87Sr/86Sr is relatively high (0.70887 鈮，
本文编号：2502186
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