Search

Integrated geochemical, U-Pb zircon, and Pb isotopic data from granitoids of the Wulandele porphyry molybdenum deposit, northeastern Inner Mongolia, are reported to disclose the possible magmatic process and Mo ore-forming process. LA-ICP-MS zircon U-Pb dating constrains the timing of the quartz diorite and monzonitic granite to 282 ± 2.4 Ma and 135.4 ± 2.1 Ma, respectively. The ages are accordant with geological facts which state that the shallow Permian granitoids are only the ore-hosting rock while the concealed Cretaceous fine-grained granite is the causative intrusion. Whole-rock geochemical data show that the granitoids belong to the high-K calc-alkaline series, and are enriched in LILEs, but depleted in HSFEs. Permian granitoids exhibit I-type characteristics, while Cretaceous granite is akin to A-type granite. Pb isotopic ratios are consistent between Permian granitoids and Cretaceous granite with ratios of 206Pb/204Pb = 18.048–18.892, 207Pb/204Pb = 15.488–15.571, and 208Pb/204Pb = 37.066–38.441. Considering geological and geochemical features together, Permian granitoids are interpreted as subduction-related continental margin high-K calc-alkaline rocks, while Cretaceous granite may be the result of the remelting of the relic Permian arc in an extensional environment induced by the rollback of the Paleo-Pacific plate. Different from classical porphyry-type deposits, the Wulandele Mo deposit, which formed in an intraplate tectonic setting, indicates that the intraplate porphyry Mo deposit should be one of the important exploration targets in the Central Asian Orogenic Belt, especially its eastern segment.

Alkaline rock-type rare-earth (RE) ores have significant utilisation value. However, the exploitation of such resources faces great challenges owing to the complex mineral and element assemblages. Composite collectors exhibit excellent performances, which may provide solutions to the flotation problem of alkaline rock-type RE ores. Therefore, 16 collectors typically used in RE ores flotation were selected. Flotation tests were performed to identify collectors with high selectivity and collection ability for RE minerals, then nine composite collectors were prepared by combining the satisfactory collectors. The flotation performances of single and composite collectors for RE minerals were examined, and the composite collector FA301 with different carbon chain lengths was identified as the best one. When FA301 was applied in optimal conditions of slurry temperature, grinding size, collector and inhibitor dosage, RE concentrate yield of 6.29%, REO grade of 32.013%, and recovery of 59.02% were achieved. According to the results of the zeta potential, FTIR, and XPS test, the functional groups (dominated by carboxyl groups) in FA301 chemically adsorbed onto the main active sites (La, Ce, Y, etc.) on the surface of RE minerals. The findings can provide scientific basis for the development of efficient collectors to facilitate the exploitation of RE resources.

The large Shuangwang gold deposit (>80 t gold) is located in the Western Qinling Orogen (WQO) of central China. It is an orogenic-type gold deposit hosted in an NW-extending breccia belt in the Devonian Xinghongpu Formation. Gold mineralization of the Shuangwang deposit is featured by hydrothermal breccia ores with strata fragments cemented by hydrothermal minerals dominated by ankerite, quartz, and pyrite with minor amounts of calcite and albite. Pyrite is the major gold-hosting sulfide and the most abundant ore mineral. Crystal habits, thermoelectricity, and trace-element composition of pyrites from the main ore-forming stage of the Shuangwang gold deposit were studied by microbinocular, BHTE-06 thermoelectric coefficient measuring instrument, and high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). Spatial distribution of the above data for pyrites was delineated by contour maps of morphology index, P-type frequency, and primary halo elements (e.g., supraore halo elements Ba and Sb; near-ore halo elements Pb, Zn, and Cu; and subore halo elements Co, Mo, and Bi). Based on the above results, four target areas (areas between prospecting lines 0 and 1, between lines 14 and 18 below orebody KT9; areas between prospecting lines 30 and 34, between lines 44 and 46 below orebody KT8) were put forward for deep gold exploration in the future. These targets are consistent with the depth extrapolation of proven gold orebodies, indicating the practicality of typomorphic characterization of pyrites as vector to deep/concealed gold orebodies. The effectiveness of the pyrite typomorphic parameter for deep gold prediction seems to be chemical composition, crystal habits, and then thermoelectricity.

The Haoyaoerhudong gabbro is a mafic intrusion located in the Haoyaoerhudong gold deposit, which is a giant gold deposit (148 t Au) hosted in Proterozoic strata on the northern margin of the North China Craton. In this paper, we present integrated SHRIMP U⁻Pb, geochemical and Sr⁻Nd isotopic data from gabbro of the Haoyaoerhudong gold deposit to reveal the magmatic processes behind its origin. SHRIMP zircon U⁻Pb dating constrains the timing of crystallization of the Haoyaoerhudong gabbro to 278.8 ± 0.81 Ma. Whole-rock geochemical results indicate that the Haoyaoerhudong gabbro has calc-alkaline features with enrichments of large-ion lithophile elements (LILE) and light rare-earth elements (REE) as well as depletions of high-field strength elements (HFSE). The relatively high (87Sr/86Sr)i (0.7053 to 0.7078) and low εNd(t) (−4.6 to −15.1) values of the gabbro indicate the involvement of crustal materials. Low Ce/Pb ratios (1.35 to 7.38), together with nearly constant La/Sm and Th/Yb ratios and variable Ba/Th and Sr/Nd ratios, suggest that the ancient mantle was modified by slab dehydration fluids. Based on new geochemical data and regional geological investigations, we propose that both the Haoyaoerhudong gold deposit and the Haoyaoerhudong gabbro formed in a post-orogenic extensional setting.