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By analyses on the trace elements of coals, host-rocks and wall-rocks, this study aims to trace the sources and evaluate the utilization prospects of REE+Y (REY) in coals from Bayili Coal Mine (Wensu, Xinjiang, China). The distribution patterns of REY in the coals are divided into two groups, flat-type and heavy REE-enrichment type (H-type). The REY of the former was mainly from the gneisses of the basement of the coal-bearing basin, and that of the later was partly from hydrothermal solution. The host-rocks show two types of REY patterns, middle REE-enrichment type (M-type) and H-type, which are due to the injection of REY from acid terrestrial water and hydrothermal solution, respectively. Almost all the coal samples are plotted into the promising area on the diagram of percentage of critical elements (REYdef, rel) vs ratio of sum of critical elements to the sum of excessive elements (Coutl) and half of the coal samples have high contents of Ga closing to the cut-off grade of Ga deposit as by-product, which indicate that the REY and Ga in Bayili Coal Mine are of utilization prospects as by-product.

Volcanic rocks preserved in the Houay kham area, Loei Fold Belt are important components of the giant Paleo-Tethyan igneous belt. These magmatic rocks, previously mapped as Triassic-Jurassi...

The Ningwu Volcanic Basin (NVB), located in the Lower Yangtze Metallogenic Belt, is characterized by the widespread occurrence of porphyritic iron-ore deposits. These deposits are clustered in thre...

The Cretaceous Huahui basin lies along the Dunhua–Mishan fault (Dun–Mi fault), which is one of the northern branches of Tan–Lu fault in northeastern China. The study of the formation and the tectonic movements that took place in the basin can provide very important information for deciphering the tectonic evolution of northeastern China during Cretaceous–Early Cenozoic. The field analysis of fault-slip data collected from different units in the basin, demonstrates changes in the paleo-stress state that reveals a three-stage tectonic movement during the Cretaceous–Early Cenozoic. The earliest tectonic movement was NW–SE extension, which was responsible for the formation of the basin and sedimentary infilling during the Early Cretaceous. Dating of the andesite in the fill indicates it began during about 119.17 ± 0.80 Ma. The extensional structures formed in the Latest Early Cretaceous imply that this tectonic movement lasted until the beginning of the Late Cretaceous. The second stage began during the Late Cretaceous when the tectonic stress state changed and was dominated by NW–SE compression and NE–SW extension, which caused the inversion of the extensional basin. This compression folded the Early Cretaceous deposits and reactivated pre-existing faults and uplifted pre-existing granite in the basin. The strata and the unconformity in the basin shows that this compressive phase probably took place during the Late Cretaceous and ended in the Early Paleogene by a compressional regime with NE–SW compression and NW–SE extension that constitutes the third stage. The tectonic stress fields documented in the Huahui basin provide insight into the influences of plate tectonics on the crustal evolution of northeastern China during the Cretaceous to Early Cenozoic. These results show that the development of Huahui basin was controlled by the northwestward subduction of the paleo-Pacific plate during the Cretaceous, and later by the far-field effects of India–Asia collision in the Paleogene.

Three generations of calcite veins filling in fractures have been recognized in Dabashan Thrust and Fold Belt in China. Reconstruction of the paleostress states corresponding to and studies on fluid inclusions and stable isotopes from the wall-rocks and the veins filled in the fractures have been carried out. The first vein, which occurs in the fractures limited to competent bed and perpendicular to the layer, was precipitated from liquids during diagenesis. Homogenization temperatures (Th) of fluid inclusions in the veins range from 126°C to 267°C, which are similar to those obtained by the wall-rocks, i.e., from 152°C to 227°C. The second-generation veins were filled in three groups of faults corresponding to NE-SW compression. Homogenization temperatures of the fluid inclusions show bimodal distribution, with peak Th-population values from 140°C to 210°C and 230°C to 270°C. The salinity values exhibit evidently two groups either. The bimodal distribution of both homogenization temperatures and salinities indicates that the fluid flowing within the fractures posses two stages of evolution. The third-generation vein was filled in NNW-SSE to NWW-SEE trending strike-slip faults, which were formed under NW-SE tectonic compression. The homogenization temperatures obtained by fluid inclusions in the veins range from 101°C to 257°C. The wide change in Th values possibly indicates that re-equilibrium has occurred for the fluid inclusions during the activity of the faults. The δ 13 C and δ 18 O values of the wall rocks range from -1.6‰ to 5.6‰ and 16.7‰ to 25.2‰, respectively. The values of δ 18 O are similar to or lower slightly than marine carbonate(29‰). The δ 13 C and δ 18 O values of the first-generation veins are from -1.8‰ to 2.2‰ and 18.4‰ to 23.1‰, respectively, which are similar to those of wallrocks except showing smaller variation. The δ 13 C and δ 18 O values of the second-generation veins range from -9.2‰ to 4.7‰ and 13.2‰ to 27.9‰. Compared to wallrocks and the first-generation veins, the second-generation veins exhibit larger variability in both δ 13 C and δ 18 O values. The third-generation veins show similar situation to the second-generation veins in δ 13 C values and the large variation in carbon isotopic compositions with the δ 13 C values from -9.2‰ to 4.8‰. But the δ 18 O values are not as large variable as that of the second-generation veins, and the δ 18 O values are from 12.8‰ to 19.8‰. The δD values measured by fluid inclusions from the second- and third-generation veins are from -62‰ to -90‰ and -74‰ to -87‰, respectively. On the plot of δ 18 O fluids vs δD fluids , parts of samples are fall in the scope of formation water, some samples show slightly lower δD values relative to formation water.

High-pressure(HP) veins were extensively developed in western Tianshan high-pressure(HP) metamorphic belt. The HP vein and host-rocks were analyzed by electronic microprobe to trace the origin of vein-forming fluids. Analytical data show that the immediately adjacent host-rocks of the studied HP vein are eclogites and gradually turned into blueschist as the distance from the veins increases, which indicates that the vein-forming fluid was derived from adjacent host-rocks; the boundaries between the vein and the host-rocks are sharp, which indicates that the fracture of the host-rocks is brittle during the vein-forming process. It is suggested that this type of HP veins is precipitated from the liquid formed by the dehydration of the host-rocks during the prograde metamorphism from blueschist to eclogite facies, which results in hydrofracturing of the rocks and provides the space for the vein to precipitate. The width of the eclogite-facies host-rocks is usually 1–2 cm, which provides the direct evidence that the fluid flow is on centimeter-scale.

Shaxi porphyry Cu-Au deposit was one of the important discoveries of the exploration in the middle-lower reaches of Yangtze River in China in 1970’s. Gold occurrence in the Shaxi porphyry copper-gold deposit (central Anhui province, eastern China) was investigated by means of microscope analyses, EPMA and PIXE. Combined with geological and mineralogical methods, the characteristies of occurrence of gold in the large scale sulfide mineralization in this region were fully investigated. The results show that gold distributes in both chalcopyrite and pyrite as submicroscopic inclusions (less than 1 µm). Au is positively correlated with As, Fe, S, Cu, Zn and Ti. The condition of gold transformation in thermal fluid system controlling deposition of Au in the region is probably the oxidation potential of the red sedimentary rocks of shale and fine grain sandstone which may be crucial as a geochemical barrier to the reducing fluid. This study lays foundation for the further research and exploration of the porphyry copper-gold deposit both theoretically and practically in the lower reaches of Yangtze region.

Since the mid-late Eocene, North China has been subjected to extensional stress, resulting in the formation and development of basins. The dynamic origin of this crustal extension has long been an issue of debate. This paper presents the results of kinematic analyses of faults obtained from two seperated areas in North China. In the Weihe graben situated on the southernmost margin of the Ordos block, analyses of fault kinematics were coupled with an analysis of the basin's subsidence history. Three successive extensional tectonic phases accompaning the basin's formation and development have been distinguished. The Palaeogene extension was oriented in a WNW-ESE direction; the Neogene extension in a NE-SW direction and the Pliocene-Quaternary extension in a NW-SE direction. Such changes have also been recorded by fault kinematics along the southern Tanlu fault zone. This has been demonstrated by three successive sets of fault striations indicating normal dip slip resulting from NW-SE extension, then left-lateral slip with a normal component resulting from NE-SW extension, and right-lateral slip with a minor normal component, respectively. The kinematic history of faults and their chronological evolution indicate changes in continental dynamics acting in North China over Cenozoic time.