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• Two convergent basins and one collisional basin formed at 1.4, 0.93 Ga, and 1.2 Ga. • 1.4 and 0.9 Ga subduction-related A- and I-type granites generated in western XAB. • Evolution of the XAB related to process from the Nuna breakup to Rodinia assembly. The Xing'an-Airgin Sum Block (XAB) is located in central and northern Inner Mongolia, North China, and belongs to one of the oldest blocks in the Central Asian Orogenic Belt (CAOB). Previous studies have shown that there are Mesoproterozoic granites in the XAB; however, the formation process of the Precambrian basement, and also the tectonic evolution and origin of the block are unclear. In this work, the Mesoproterozoic and early Neoproterozoic stratigraphic sequences, ages and the related sedimentary basin types of the western XAB are reported for the first time. Our study reveals that the Mesoproterozoic to early Neoproterozoic stratigraphic sequence contains the Baoyintu Group and Airgin Sum Group with respective depositional ages of 1516–1392 Ma, and 1237–921 Ma. Sedimentation analysis suggests that the Baoyintu Group and the Airgin Sum Group formed in the coastal marine environment with clastic and carbonate provenances and the shallow marine clastic sedimentary environment, respectively. The age distribution patterns of detrital zircons indicate that there were two different types of sedimentary basins, including two convergent basins formed in ∼ 1400 and ∼ 930 Ma, and a collisional basin developed in ∼ 1237 Ma. However, the 1392–1379 Ma syenogranites and alkali-feldspar granites, which are geochemically similar to A-type granites, were generated by the partial melting of mixed Paleo- and Mesoproterozoic crustal materials in an extensional setting. The newly identified early Neoproterozoic I-type granite (921 Ma) was derived from reworking of the Paleo- to Mesoproterozoic crustal source in a hydrous, garnet-free and plagioclase residual condition. These geochemical signatures, coupled with the three sedimentary stages included on the block, suggest that the 1.4–1.3 Ga period recorded an extensional regime at a convergent continental margin (e.g., back-arc basin), whereas the early Neoproterozoic period was likely controlled by a continental arc setting. In summary, the tectonic evolution process of the XAB documented by three sedimentary and two magmatic events could be its response to the supercontinent cycle from the Nuna breakup to the Rodinia assembly. [ABSTRACT FROM AUTHOR]

Understanding the modes of occurrence of elements in coal is important, not only to help properly evaluate the impacts of potentially toxic elements on the environment and human health but also to provide technical guidance for recovering critical elements from coal ash. Statistical and multivariate data analysis methods have widely been used, together with physical and chemical methods, to determine the modes of occurrence of elements in coal. However, some of the statistical methods, e.g., average linkage hierarchical clustering algorithm have some disadvantages (e.g., statistical errors and poor visualization). A self-organizing map is an unsupervised artificial neural network, and it is known for its high data mining capability and excellent data visualization. In contrast to the average linkage hierarchical clustering algorithm that is commonly used for analyzing the modes of occurrence of elements in coal, the self-organizing map algorithm can provide a topological relationship among elements instead of merely providing the groups to which the elements belong. This paper focuses on the application of self-organizing map to coal elemental data for analyzing the modes of occurrence of elements in coal. Samples used in this study are from the Adaohai, Hailiushu, and Datanhao mines, all located in the Daqingshan Coalfield, Inner Mongolia, China. The results obtained from the self-organizing map algorithm are compared with those produced by average linkage hierarchical clustering algorithm. Based on the previous investigations (mainly direct methods) and further analysis, it can be concluded that the results from the self-organizing map algorithm in this investigation are more consistent with the geochemical nature and previous investigations by direct methods than those from average linkage hierarchical clustering algorithm. Consequently, the self-organizing map algorithm is a new reliable and intuitive method for analyzing the modes of occurrence of elements in coal. [ABSTRACT FROM AUTHOR]