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- Title
热水沉积区黑色页岩稀土元素特征及其地质意义:——以贵州中部和东部地区下寒武统牛蹄塘组页岩为例
- Authors
贾智彬; 侯读杰; 孙德强; 姜玉涵; 赵喆; 张自鸣; 洪梅; 畅哲; 董立成
- Abstract
In this paper, the Lower Cambrian Niutitang Fm shale in Guizhou was taken as an example to figure out the relationship between hydrothermal sedimentation and high-quality source rock development. Firstly, 22 samples taken from 5 sections in Guizhou (i.e.Lianxing-cun section in Bijie, Wenshui-cun section in Guiyang, Zhongnan-cun section in Zunyi, and Yangtiao-cun section and Jiumen-cun section in SE Guizhou) were tested for major elements and rare earth elements (REEs), in order to identify the characteristics of REEs under the effect of hydrothermal sedimentation. Then, the hydrothermal activity intensity and the sedimentary genesis of black shale were distinguished according to the REE characteristics. Finally, combined with total organic carbon (TOC) content, the relationship between hydrothermal sedimentation and high-quality source rocks was discussed. The following results were obtained. First, the deposition at the bottom of the Niutitang Fm is jointly controlled by terrestrial input, marine deposition and hydrothermal activity. The light and heavy REEs are obviously differential in the vertical direction. The heavy REEs are enriched at the bottom, while the light ones are enriched at the top. Extremely low REE content is only observed in the Yangtiao- cun section with the strongest hydrothermal activity. Second, there are two hydrothermal activity centers near the Yangtiao-cun and Zhongnan- cun sections, respectively. The influential intensity of hydrothermal activity increases from the west to the east in the study area, and the coverage of hydrothermal sedimentation intends to extend southeastwards to the Jiumen section. Third, δEu/Al (europium anomaly/aluminum) and δY/Al (yttrium anomaly/aluminum) are lower in the black shale formed in normal marine sedimentation and low-temperature hydrothermal sedimentation, and increase with the hydrothermal sedimentation intensity. And fourth, TOC of source rocks with δEu greater than 1 is higher. When δEu/Al and δY/Al range between 5 and 10, the low-temperature hydrothermal sedimentation is favorable for the enrichment and preservation of organic matters, and plays a positive role in the formation of high-quality source rocks.
- Publication
Natural Gas Industry, 2018, Vol 38, Issue 5, p44
- ISSN
1000-0976
- Publication type
Article
- DOI
10.3787/j.issn.1000-0976.2018.05.005