Geochemical characteristics and geologic significance of rare earth elements in oil shale of the Yan’an Formation in the Tanshan area, in the Liupanshan Basin, China

Abstract

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.

Chemical Characteristics of Coil Heavy Metal Elements and Ecological Security Risks Caused by Fertilization

“…e principal component analysis is a method that converts multiple indexes into a few comprehensive indexes to reflect the original data information, which is used to distinguish various metal sources in soil research. Elements with a high load on the same principal component may have similar sources [13]. Principal component analysis of heavy metal elements in the research area showed that 3 principal components were extracted from the eight heavy metal elements (see Table 3).…”

Rare earth elements in aeolian loess sediments from Menyuan Basin, northeastern Tibetan plateau: Implications for provenance

“…The granites contained a relatively high concentration of rare earth elements, being enriched in LREE, having high LREE/HREE ratios, and exhibiting significant negative Eu anomalies. In contrast, the basal basalts were relatively low in rare earth elements and moderately increased in HREE, with low LREE/HERR ratios and minor Eu anomalies (Cullers and Graf, 1984;Condie, 1993;Hai et al, 2021). The Menyuan loess has low rare earth elements and HREE contents, high LREE/HREE ratios, and substantial negative Eu anomalies; hence, it is doubtful that the Menyuan loess source rocks are basaltic, but rather granite and sedimentary rocks.…”

The Sequence Stratigraphic Division and Depositional Environment of the Jurassic Yan’an Formation in the Pengyang Area, Southwestern Margin of the Ordos Basin, China

“…The Yan'an Formation of the Middle Jurassic is the main coal-bearing stratigraphic unit in the study area. According to the data in published papers, the Yan'an Formation has a large variation in depositional thickness and lithology and is a sandstone-conglomerate-mudstone assemblage with predominantly fluvial deposits, along with local sections deposited in lake and marsh phases [27][28][29]. Depending on their lithology and depositional environment, they can be regionally divided into four lithological members.…”