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Abstract: The abundances of nine major elements and thirty-eight trace elements in 520 samples of low sulfur coals from the Zhuji Mine, Huainan Coalfield, Anhui, China, were determined. Samples were mainly collected from 10 minable coal seams of 29 boreholes during exploration. The B content in coals shows that the influence of brackish water decreased toward the top of coal seams; marine transgression and regression occurred frequently in the Lower Shihezi Formation. A wide range of elemental abundances is found. Weighted means of Na, K, Fe, P, Be, B, Co, Ni, Cr, Se, Sb, Ba, and Bi abundances in Zhuji coals are higher, and the remainder elements are either lower or equal to the average values of elements in coals of northern China. Compared to the Chinese coals, the Zhuji coals are higher in Na, K, Be, B, Cr, Co, Se, Sn, Sb, and Bi, but lower in Ti, P, Li, V and Zn. The Zhuji coals are lower only in S, P, V and Zn than average U.S. and world coals. Potassium, Mg, Ca, Mn, Sr, As, Se, Sb and light rare earth elements (LREE) had a tendency to be enriched in thicker coal seams, whereas Fe, Ti, P, V, Co, Ni, Y, Mo, Pb and heavy rare earth elements (HREE) were inclined to concentrate in thinner coal seams. The enrichment of some elements in the Shanxi or Upper Shihezi Formations is related to their depositional environments. The elements are classified into three groups based on their stratigraphic distributions from coal seams 3 to 11-2, and the characteristics of each group are discussed. Lateral distributions of selected elements are also investigated. The correlation coefficients of elemental abundances with ash content show that the elements may be classified into four groups related to modes of occurrence of these elements. [Copyright &y& Elsevier]

Abstract: The comprehensive information of coal quality and its relationship with coal-forming environment in Zhuji exploration area, Huainan coalfield Anhui, China, have been studied. The data of coal quality including proximate and ultimate analysis, calorific values, sulfur forms, petrography and selected trace elements (Ga, Ge, V, U, Th, Cl and As) are based on 614 samples of 13 minable coal seams from 88 drilling holes collected during exploration periods. These data were designed to provide information on the technological performance of coal. Characteristics of coal quality deposited in three different sedimentary environments, namely in coal-bearing strata of the Shanxi Formation, Lower Shihezi Formation and Upper Shihezi Formation, were analyzed. Results show that moisture, volatile matter, and ash yield all increase stratigraphically upward, which is opposite to the variation of calorific values. The correlation between ash yield and calorific value shows negatively higher relevance that than of moisture and ash yield. The coal quality parameters of the boreholes along the divided faults were rarely controlled by geological setting. It was suggested that other factors such as magmatic activity and underground water cycling may modify the parameters of coal quality to some extent and cause their redistribution. [Copyright &y& Elsevier]

Abstract: Rare earth element (REE) concentrations in coals are a source of information relevant to the evolution of source rocks, depositional environment, and epigenetic tectonic activity as well as the effects of igneous intrusions. In this study, 186 coal samples, 11 intrusion-affected coal samples, 4 samples representative of the intrusive rocks, one coal roof and one parting samples were collected from 29 boreholes at the Zhuji coal mine, Huainan Coalfield, Anhui Province, China. The main objective is to characterize the intrusive rocks in the coal-bearing sequence and to investigate the correlation of REE parameters in the coals with the source rocks, depositional environment, localized faults, igneous intrusions, and thickness of the coal beds. A sequence (from base to top) of acidic to basic intrusive rocks through the coal-bearing strata was identified, which possibly corresponds to different intrusive episodes of granite, diorite/monzonite and gabbro. Both the REE contents and degree of fractionation of light rare earth elements (LREE) and heavy rare earth elements (HREE) increase from acidic to basic rocks. Most rocks are slightly depleted in Ce but highly depleted in Eu. The REE concentrations in coals from the Zhuiji mine (average of 118μg/g) are nearly identical to recently-updated average Chinese values, but significantly higher than global values. The REE content of the intrusion-affected coals is not distinctively different from that of the other coals (P=0.2), and REE concentrations of the igneous rocks appear to have no clear relationship to those of the intrusion-affected coals. The depositional environment and source rocks are presumably the main REE contributors to the coal-accumulation basin. The REE content in coals from fault-affected boreholes is higher than that in other boreholes and this trend is stronger in the coal seams of the upper strata. The HREE tend to be incorporated into thinner coal seams and the degree of fractionation between LREE and HREE of the coal-forming materials increases with coal thickness. [Copyright &y& Elsevier]

To investigate the magnitude to which the carbon isotopic ratio (δ 13 C) varies in coals in response to their contemporary terrestrial environment, the Early-Middle Permian Huainan coals (including coals from the Shanxi Formation, Lower Shihezi Formation and Upper Shihezi Formation) in North China were systematically sampled. A 2.5‰ variation range of δ 13 C values (−25.15‰ to −22.65‰) was observed in Huainan coals, with an average value of −24.06‰. As coal diagenesis exerts little influence on carbon isotope fractionation, δ 13 C values in coals were mainly imparted by those of coal-forming flora assemblages which were linked to the contemporary climate. The δ 13 C values in coals from the Shanxi and Lower Shihezi Formations are variable, reflecting unstable climatic oscillations. Heavy carbon isotope is enriched in coals of the Capitanian Upper Shihezi Formation, implying a shift to high positive δ 13 C values of coeval atmospheric CO 2 . Notably, our study provides evidence of the Kamura event in the terrestrial environment for the first time. [ABSTRACT FROM AUTHOR]

The Huainan coalfield situated in the southern margin of North China Plate contains coal deposits of Carboniferous–Permian age. The 1 and 3 seams of the Early Permian Shanxi Formation and seams 4-1, 4-2, 5-1, 7-2 and 8 of the Late Early Permian Lower Shihezi Formation were analyzed for coal petrography, mineralogy and geochemical parameters. Collected data were designed to offer basic information on the assessment of coal quality and further to reveal possible factors controlling on coal quality. The shift of basin subsidence center from Huaibei coal-bearing basin to Huainan coal accumulation region caused the change of coal-forming environment (groundwater table, detrital matters and swamp style) which may further cause the differences in coal quality. The average vitrinite contents, ash yields and mineral matters are higher in the Lower Shihezi Formation coals than in the Shanxi Formation coals. The contents of vitrinite sharply decrease upward within coal seam 4, whereas the inertinite contents, ash yields and mineral matters show opposite trend which may be attributed to the relatively high-accommodation settings produce coals usually in the form of an upward high-to-low vitrinite succession. Two groups of elements are classified among coal seams. According to the vertical variation of elements contents among coal seams, most of elements in Group 1 are depleted in coal seam 4-2 except for Be, B, Sc, Fe, Mg, Ca, Li, Sn while almost all the elements in Group 2 are enriched in coal seam 4-2. [ABSTRACT FROM AUTHOR]