Rare earth elements geochemistry characteristics and their geological implications of lacustrine oil shale from Chang 7 oil layer in southern Ordos Basin, China

In the Tanshan area, which is at the Liupanshui Basin, abundant oil shale resources are associated with coals. We analyzed the cores, geochemistry of rare earth elements (REE) and trace element of oil shale with ICP-MS technology to define the palaeo-sedimentary environment, material source and geological significance of oil shale in this area. The results of the summed compositions of REE, and the total REE contents (SREE), in the Yan'an Formation oil shale are slightly higher than the global average of the composition of the upper continental crustal (UCC) and are lower than that of North American shales. The REE distribution pattern is characterized by right-inclined enrichment of light rare earth elements (LREE) and relative loss of heavy rare earth elements (HREE), which reflects the characteristics of crustal source deposition. There is a moderate degree of differentiation among LREE, while the differences among HREE are not obvious. The dEu values show a weak negative anomaly and the dCe values show no anomaly, which are generally consistent with the distribution of REE in the upper crust. The characteristics of REE and trace elements indicate that the oil shale formed in an oxygen-poor reducing environment and that the paleoclimatic conditions were relatively warm and humid. The degree of differentiation of REE indicates that the sedimentation rate in the study area was low, which reflected the characteristics of relatively deep sedimentary water bodies and distant source areas. The results also proved that the source rock mainly consisted of calcareous mudstone, and a small amount of granite was also mixed in.

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Geochemical occurrences of rare earth elements in oil shale from Huadian

Journal of Fuel Chemistry and Technology ◽

10.1016/s1872-5813(11)60032-7 ◽

2011 ◽

Vol 39 (7) ◽

pp. 489-494 ◽

Cited By ~ 4

Author(s):

Jing-ru BAI ◽

Qing WANG ◽

Yan-zhen WEI ◽

Tong LIU

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Oil Shale

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Geochemistry Characteristics of Rare Earth Elements in Quartz of Chahe Copper Deposit, Yuanjiang, Yunnan

Acta Geologica Sinica - English Edition ◽

10.1111/1755-6724.12372_9 ◽

2014 ◽

Vol 88 (s2) ◽

pp. 366-367

Author(s):

Ping LI ◽

Zhengqi XU ◽

Hao SONG ◽

Ye WANG ◽

Jing ZHAO ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Copper Deposit ◽

Geochemistry Characteristics

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Petrography and geochemical characteristics of Chang 7 sandstone in Yanhe profile, Ordos Basin: Implication for paleoenvironment and tectonic background

Interpretation ◽

10.1190/int-2019-0158.1 ◽

2020 ◽

Vol 8 (4) ◽

pp. T981-T990

Author(s):

Haijun Gao ◽

Delu Li ◽

Dingming Dong ◽

Hongjun Jing ◽

Hao Tang

Keyword(s):

Grain Size ◽

Rare Earth ◽

Rare Earth Elements ◽

Ordos Basin ◽

Island Arc ◽

Geochemical Characteristics ◽

Hydrocarbon Exploration ◽

Source Rocks ◽

Grain Size Analysis ◽

Alkaline Basalt

The Chang 7 oil layer from the upper Triassic Yanchang Formation is an important layer for hydrocarbon exploration. Most studies on the Chang 7 oil layer have focused on the source rocks, while research on the sandstone is still inadequate, especially on the petrography and geochemical characteristics. Using seven sandstone samples of the Chang 7 oil layer in the Yanhe profile, the grain-size analysis, major elements, trace elements, and rare earth elements were tested. The results find that the sandstone of fine-grained sediments of the Chang 7 oil layer is dominated by arkose with a minor number of lithic arkose. The range of grain size (Mz) is from 2.72 to 3.92 Φ, and the C value and M value of the sandstone samples suggest characteristics of turbidity deposition. The Al/Si ratios of all of the samples imply high clay mineral content. The results of trace and rare earth elements demonstrate the reducing condition, freshwater, and cold and dry weather. The provenance of the sandstone samples is mainly from island arc acidic volcanic rock, and the type of provenance is mixed with sedimentary rock, granite, and alkaline basalt. The tectonic background is continental island arc. This study provides a systematic geologic foundation for the formation of sandstone of Chang 7 oil layer in Ordos Basin.

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Rare Earth Elements in No. 2 Coal of Huangling Mine, Huanglong Coalfield, China

Energy Exploration & Exploitation ◽

10.1260/0144-5987.30.5.803 ◽

2012 ◽

Vol 30 (5) ◽

pp. 803-818 ◽

Cited By ~ 18

Author(s):

Cunliang Zhao ◽

Dujuan Duan ◽

Yanheng Li ◽

Jianya Zhang

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Depositional Environment ◽

Ordos Basin ◽

Average Concentration ◽

Source Rocks ◽

Tectonic Activity ◽

Geochemical Anomaly ◽

Metallogenic Belt ◽

Reported Data

Rare earth elements (REEs) can provide lots of information relevant to the evolution of source rocks, depositional environment, and epigenetic tectonic activity. In this study, 14 bench samples (including 11 coals, 1parting, 1roof and 1floor) of the No. 2 coal seam from Huangling Mine, Huanglong Coalfield, Ordos Basin, China were collected to study the REE geochemistry. The average concentration of REEs is 44.03 μg/g, and it is lower than those in coals of the Chinese and world coal. The coals are enriched in light REEs and the LREEs-HREEs have been highly fractionated, with an average (La/Yb) N of 11.38. The values of Ce/Ce* are more or less than 1 (with an average 0.92) and indicates that the anomaly of Ce is very slight. However, the values of Eu/Eu* (with an average 7.69 of coal) are distinctly higher than reported data of coals. The extremely high contents of Ba caused the geochemical anomaly of REEs. The Ba2+ was origin from the barium metallogenic belt in Qinling Old-upland.

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Provenance and Tectonic Setting of Lower Cretaceous Huanhe Formation Sandstones, Northwest Ordos Basin, North-Central China

Minerals ◽

10.3390/min11121376 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1376

Author(s):

Xiaoneng Luo ◽

Ziying Li ◽

Yuqi Cai ◽

Chao Yi ◽

Zilong Zhang ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Lower Cretaceous ◽

Chemical Weathering ◽

Tectonic Setting ◽

Ordos Basin ◽

Distribution Patterns ◽

Passive Margin ◽

Central China ◽

Average Value

In adjustment to fulfill the requirements of the investigation regarding the lower Cretaceous sandstone uranium deposit in the Naogaodai area within the northwest of Ordos Basin, twenty-seven sandstone samples obtained from the Lower Cretaceous Huanhe Formation were analyzed for major, trace and rare earth elements (REE). The source of clastic and tectonic background was additionally analyzed. The results show that Huanhe sandstone is feldspar rich sandstone, and also the mineral composition is principally quartz, albite and plagioclase; the ratio of light to heavy rare earth elements (LREE/HREE) is 9.25–10.83, with an average value of 10.00; (La/Yb)CN is 10.20–12.53, with an average value of 11.24, demonstrating that LREE is enriched and fractionated compared with HREE. REE distribution patterns are similar, which additionally reveals that Huanhe sandstone has a homogenous source; the Index of Compositional Variability (ICV) value is 1.17–1.73, with an average value of 1.35, both greater than 1, showing an immature property, which may be first-order cycle deposition. The average value of the Chemical Index of Alteration (CIA) is 50.29, suggesting that the source rock has encountered weak chemical weathering; sandstones are near-source first-cycle provenance, which is not significantly influenced by sedimentary sorting and recycling. The geochemical qualities further indicate that Huanhe sandstone was deposited in a passive margin and experienced moderate weathering.

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