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- Title
柴达木盆地北缘平台地区下干柴沟组下段 稀土元素特征及物源分析.
- Authors
蒋 赟; 潘世乐; 秦彩虹; 蒋峥文; 朱文军; 张明峰; 孙国强
- Abstract
Fluvial facies clastic rocks are mainly developed in the lower part of the Lower section of Xiaganchaigou Formation of Paleogene in the tectonic belt platform area in the northern margin of Qaidam Basin. By analyzing and testing the main trace elements in the drilling core samples of the Lower section of Xiaganchaigou Formation, the results showed that the total content of rare earth elements(∑REE)was between 125.96 μg/g and 169.91 μg/g, with an average value of 151.11 μg/g.(La/Yb)N value ranged from 8.99 to 11.29, with an average of 9.91.(La/Sm)N value ranged from 3.42 to 4.10, with an average of 3.80.(Gd/Yb)N value ranges from 1.51 to 2.25,with an average of 1.73. On the whole, it is characterized by enrichment of light rare earth el⁃ ements,loss of heavy rare earth elements, and negative anomaly of Eu. Ceanom anomaly index and(La/Yb)n value indicate that the sedimentary water at that time is in an oxidizing environment with a faster deposition rate. The heavy mineral combination is dominated by garnet, magnetite, zircon, titanite and porphyry, and contains a small amount of tourmaline, sphene and amphibolyte. The analysis results of rare earth elements and heavy minerals show that the lithology of the lower sedimentary source area of Lower section of Xiaganchaigou Formation in the platform area is mainly granite and sedimentary rock, and a small amount comes from alkaline basalt. The tectonic setting of the study area is dominated by the continental island arc environment. By comparing the tectonic setting and bedrock types of the surrounding Laoshan, it is believed that the sediment source is mainly from the western section of Seshiteng Mountain. This study provides a geological basis for the fine division of sedimentary system and the search for favorable reservoir sand bodies in the platform area.
- Subjects
HEAVY minerals; CLASTIC rocks; PETROLOGY; SEDIMENTARY rocks; HEAVY elements; RARE earth metals; TRACE elements; YTTERBIUM
- Publication
Natural Gas Geoscience, 2020, Vol 31, Issue 11, p1537
- ISSN
1672-1926
- Publication type
Article
- DOI
10.11764/j.issn.1672-1926.2020.06.002