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The ophiolites along the North Qilian Orogenic Belt are considered to be fragments of ancient oceanic crusts and lithospheric mantle of the Palaeozoic North Qilian Ocean (a branch of the Proto‐Tethys). Compared with other ophiolites in this belt, the genesis of the Xiejiayao ophiolite has been poorly studied so far, making it difficult to understand the tectonic evolution of the ocean. In this study, we present new compositional and Sr‐Nd isotopic analyses of basaltic rocks from the Xiejiayao ophiolite to shed light on its petrogenesis and geodynamic background. These oceanic basalts are characterized by flat REE patterns, low elemental ratios of high‐field‐strength elements (e.g., La/Sm, Sm/Yb, La/Yb, Gd/Yb, [Th/Yb]PM) and abundant spinels, implying that they were generated via partial melting in the spinel stability field of the mantle. Their positive εNd(t) values (6.1–8.4), high Zr/Nb (43.65–79.40) as well as low Nb/Ta (10.91–15.09), Zr/Hf (34.64–39.28), and Nb/Yb (0.41–0.59) ratios further reflect that the ancient mantle had already become depleted to some extent before the onset of the Palaeozoic ocean. Additionally, basalts share many geochemical similarities (e.g., Zr, Y, Ti, and V) with both mid‐ocean ridge and island arc basalts. This supports the strong likelihood of origin in a back‐arc basin close to the suprasubduction zone for the ophiolite. Therefore, accompanied by the northward subduction of the oceanic lithosphere during the early Palaeozoic, a large‐scale back‐arc basin developed progressively in response to the back‐arc expansion. The Xiejiayao basaltic magmas were generated in the back‐arc basin via partial melting of the depleted mantle and their source was probably mixed with subducted melts/fluids from the dehydration and melting of oceanic slabs and sediments. [ABSTRACT FROM AUTHOR]

High‐precision measurement of X‐ray spectra is affected by the statistical fluctuation of the X‐ray beam under low‐counting‐rate conditions. It is also limited by counting loss resulting from the dead‐time of the system and pile‐up pulse effects, especially in a high‐counting‐rate environment. In this paper a detection system based on a FAST‐SDD detector and a new kind of unit impulse pulse‐shaping method is presented, for counting‐loss correction in X‐ray spectroscopy. The unit impulse pulse‐shaping method is evolved by inverse deviation of the pulse from a reset‐type preamplifier and a C‐R shaper. It is applied to obtain the true incoming rate of the system based on a general fast–slow channel processing model. The pulses in the fast channel are shaped to unit impulse pulse shape which possesses small width and no undershoot. The counting rate in the fast channel is corrected by evaluating the dead‐time of the fast channel before it is used to correct the counting loss in the slow channel. [ABSTRACT FROM AUTHOR]

Cu-Au mineralization is rare in the Jurassic-Early Tertiary batholiths related to the India-Asia collision. Geochemical analysis and U-Pb isotope chronology was carried out on Shuangbujiere biotite hornblende granodiorite from the Zedong area. Zircon grains of the biotite hornblende granodiorite show oscillatory growth zonation and have high Th/U ratios of 1.08-2.39, indicating a magmatic origin for the zircons. Geochrological test yielded a LA-ICP-MS U-Pb age of 51.5±1.0 Ma, suggesting that the emplacement age of the biotite hornblende granodiorite is Early Eocene. The Shuangbujiere biotite hornblende granodiorites have geochemical features characteristic of adakite and are associated with a calc-alkaline metaluminous I-type granite enriched in Sr, high in Mg# (49.6-54.9) and Sr/Y, and depleted in Y and Yb. These results indicate that this intrusion formation may have been associated with crustal thickening caused by the early collision of the Indian and Eurasian Plates. As the process of crustal thickening continued, the heating of the underplated basaltic magma caused the thickened lower crust amphibolite to dehydrate the melt and form a high-K calc-alkaline adakitic melt at about 848°C. Meanwhile, magma mixing of the underplated basaltic melt and high-K calc-alkaline adakitic melt formed a high-Mg# adakite representative of the sys-collisional tectonic setting. [ABSTRACT FROM AUTHOR]

The carbonaceous-siliceous-argillitic rock type uranium deposit in the Zoige area is located in the northeastern margin of the Tibetan Plateau, and has gained much attention of many geologists and ore deposit experts due to its scale, high grade and abundant associated ores. Because of the insufficient reliable dating of intrusive rocks, the relationship between mineralization and the magmatic activities is still unknown. In order to study this key scientific issue and the ore-forming processes of the Zoige uranium ore field, the LA-ICP-MS zircon U-Pb dating of magmatic rocks was obtained: 64.08±0.59 Ma for the granite-prophyry and ∼200 Ma for the dolerite. U-Pb dating results of uraninite from the Zoige uranium ore field are mainly concentrated on ∼90 Ma and ∼60 Ma. According to LA-ICP-MS U-Pb zircon dating, the ages for the dolerite, porphyry granite and granodiorite are 200 Ma, 64.08 Ma approximately and 226.5-200.88 Ma, respectively. This indicates that the mineralization has close relationship with activities of the intermediate-acidic magma. The ages of the granite porphyry are consistent with those uraninite U-Pb dating results achieved by previous studies, which reflects the magmatic and ore-forming event during the later Yanshanian. Based on the data from previous researches, the ore bodies in the Zoige uranium ore field can be divided into two categories: the single uranium type and the uranium with polymetal mineralization type. The former formed at late Cretaceous (about 90 Ma), while the latter, closely related to the granite porphyry, formed at early Paleogene (about 60 Ma). And apart from ore forming elemental uranium, the latter is often associated with polymetallic elements, such as molybdenum, nickel, zinc, etc. [ABSTRACT FROM AUTHOR]

The article discusses the research study conducted to examine the geologic history of the iron oxide copper gold (IOCG) deposits in Southwestern China that was associated with polymetallic mineralization. It reveals the age of magmatic rocks and metallogenic epoch and the coupling relationship between polymetallic elements. It also reveals the ore-forming process including the volcanic sedimentation, grenville orogenic event, and superimposed mineralization.

The article focuses on a research paper analyzing the platinum-group element (PGE) constraint on the origin mechanism of the Hetaoshu PGE deposit in the Xiaoguanhe Region in Panxi Area, China. The concentrations of PGE, copper and nickel in rock samples show that the ore forming elements consists of nickel and copper. It also evaluates the impact of sulfide segregation on the ore-forming process of Hetaoshu deposit.

The article discusses a study on lead isotopic geochemistry of Nuri copper-tungsten-molybdenum (Cu-W-Mo) Deposit and highlights its implications in Shannan Area, Southern Tibet, China. It mentions that ore sulphides of Nuri deposit have the same lead isotopic compositions as magmatic rocks. It states that ore sulphides have localized distributions within Gangdese batholith range. It also mentions that ore-bearing intrusions and ore sulphides have lead isotopic composition.