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Shizuishan is a typical exhausted resources-based city in the northern area of the Ningxia Hui autonomous region in China. In order to develop the planting industry of selenium (Se)-rich agricultural products and promote green and sustainable urban development and transformation, investigations on the quality of Se-rich land were carried out in Shizuishan City, where 7399 surface soil (0-20 cm) samples of farmlands, 30 atmospheric precipitation samples, and nine parent rocks were collected. By means of semi variogram model construction by GS

South China is a well-known grand felsic igneous rocks province. However, it is still controversial and not well understood whether the Mesozoic tectono-magmatic pattern is dominated by the subduction of the paleo-Pacific oceanic plate. In this study, we address this question by concentrating on the long-term evolutionary Guandimiao batholith, which has complex lithofacies with different formation ages and can be a superb record of the Mesozoic tectonic evolution in South China. Geochronologically, four stages of magmatism can be identified combined with previous reports: granodiorite (G1, 239 Ma), biotite monzogranite (G2-1) and two-mica monzogranite (G2-2) (230–203 Ma), granite porphyry (G3, 211–190 Ma), and lamprophyre (L4, 121 Ma). G1 and G2-1 have an affinity with I-type granite and were derived from metabasaltic to metatonalitic sources, whereas G2 and G3 show S-type granite characteristics and were derived from the para-metamorphic basement of the Cathaysia block. The L4 was derived from partial melting of garnet and spinel lherzolite and underwent mixing between Mesoproterozoic pelagic and/or terrigenous sediments and the subcontinental lithosphere mantle (SCLM) of South China. The granitoids of the Guandimiao batholith underwent intensely fractional crystallization of feldspar, Ti-bearing minerals, allanite and monazite. The zircon U–Pb dating of L4 in the Guandimiao batholith completely records the six stages of pre-Mesozoic tectonic events in the SCB. During the Mesozoic, the main body of the Guandimiao batholith (G1, G2-1 and G2-2) recorded the closure of the paleo-Tethys Ocean in the Triassic and the subsequent regional extension of the postcollision. G-3 and L4 of the Guandimiao batholith documented the transition of tectonic and dynamic regimes in the early Yanshanian and the rollback and steep subduction of the paleo-Pacific Ocean in the late Yanshanian.

The safety of drinking and irrigation water is an issue of great concern worldwide. The rational development and utilization of water resources are vital for the economic and societal stability of Altay, an extremely arid area. In this study, three types of water samples (25 river waters, 10 groundwaters, 6 lake waters) were collected from main rivers and lakes in Altay and analyzed for electrical conductivity, total dissolved solids, pH, major ions (i.e., K

The Zhaibei Granite in Jiangxi Province, southern China, hosts an ion-adsorption light rare earth element (LREE) deposit. Recently, heavy REE (HREE) ores have also been reported from weathered crusts of the granitic rocks. In this study, petrological, geochemical, and mineralogical characteristics of the Zhaibei pluton were analysed to establish the genesis of this REE deposit. The pluton contains coarse-grained biotite syenogranite and minor hornblende–biotite–quartz monzonite in its central zone, medium-grained biotite syenogranite in its transitional zone, and fine-grained muscovitic alkali-feldspar granite and porphyritic muscovitic biotite–alkali-feldspar granite together with monzogranite porphyry intrusions in its marginal zone. The REE minerals include titanite, allanite, monazite, bastnasite, and thorite-(Y) in the central zone, allanite, monazite, xenotime, bastnasite, and thorite-(Y) in the transitional zone, and synchysite-(Y), thorite-(Y), and xenotime in the marginal zone. The SiO2 content increases from 62 to 77 wt% from the centre to the margin, whereas the Al2O3, TiO2, MgO, FeO, and CaO contents decrease. In addition, the size of the negative Eu anomaly and HREE content increase, accompanied by decreases in Co, Zr, Hf, Sr, and Ba and increases in Rb, Cs, Nb, and Sn. These observations indicate that the Zhaibei Granite might have been formed by crystallisation differentiation of magma. The granitic pluton was also influenced by reactions with late-magmatic F-, CO2–, and REE-rich fluids that altered magmatic minerals and crystallised as REE-fluorocarbonates and thorite. The hydrothermal REE minerals constitute ∼ 40% of the total REEs in the bedrock and are the major supplier of ion-exchangeable REEs in the ores of the Zhaibei deposit. LREE-rich ores may have been derived from the LREE-rich granitic rocks, which contain bastnasite, titanite, and allanite, whereas HREE-rich ores were sourced mainly from the HREE-rich granites, which contain synchysite-(Y) and thorite-(Y). Furthermore, REE ores with enrichment in both HREEs and LREEs were probably sourced from the monzogranite porphyry bedrock, which contains bastnasite-(Y), bastnasite, allanite, and thorite-(Y).

South China is famous for its large-scale mineralization genetically related to widespread Mesozoic granites. The Jiulongnao complex is one of the largest intrusions in southern Jiangxi Province, and is closely associated with W-dominated polymetallic mineralization. The complex comprises four intrusive phases (I-IV). Phase I consists of medium- to coarse-grained, biotite granite, whereas medium- to coarse-grained, porphyritic, biotite granite and muscovite-bearing granite comprise Phase II. Phase III is composed of medium- to fine-grained, porphyritic, biotite granite and Phase IV consists of medium- to fine-grained, garnet- and biotite-bearing granite. These intrusive phases have LA-ICP-MS zircon U-Pb ages of 160.9 ± 0.6 Ma, 158.6 ± 0.7 Ma, 157.0 ± 1.5 Ma and 154.1 ± 1.2 Ma, respectively. All of the granites are enriched in Rb, Th, U, Ta and Pb, and significantly depleted in Eu, Ba, Nb, Sr, P and Ti. They have eHf(t) and eNd(t) values ranging from −17.9 to −8.2, and −10.7 to −9.8, respectively, with two-stage Hf model ages of 1.7–2.3 Ga. They are S-type granites derived by partial melting of Paleo-Proterozoic metasedimentary rocks. The four phases have TZr of 746–760 °C, 712–802 °C, 798–810 °C, and 648–731 °C, respectively. Oxygen fugacities of Phases I to III display a decreasing trend but Phase IV has much higher oxygen fugacity in its early stage, which decreased in the late stage. The four phases have different accessory mineral assemblages: Phase I is characterized by an assemblage of zircon, apatite, fergusonite, thorite and uraninite, whereas Phase II is rich in thorite, uraninite, REE-bearing minerals (e.g., monazite, fergusonite and xenotime) and fluorite. Monazite is the main accessory mineral in Phase III, whereas Phase IV contains a wide range of minerals, including thorite, uraninite, Nb-Ta-bearing minerals (e.g., fergusonite and pyrochlore), cassiterite and rutile. These mineral assemblages, together with other geological and geochemical features, suggest that W mineralization was genetically related to Phases I, II and IV, whereas U mineralization was most extensive in Phase II. Sn, Nb and Ta mineralization was associated with the highly fractionated of magmas of Phase IV.

South China hosts more than 80% W reserves of China and about 50% of the world, with thousands of world-class W deposits of various types. Recently, more and more giant W deposits have been discovered in both the Nanling region to the south and the Yangtze River region to the north, such as the Zhuxi, Dahutang, Pangushan, and Taoxikeng deposits. In this paper, based on previous publications and new exploration results of the W deposits in South China, the majority of such deposits are reviewed, and are divided into 8 types: quartz-vein, skarn, greisen, porphyry, granite veinlet-disseminated, fractural-hydrothermal, stratabound, and weathering-placer types. Those deposits are closely related to the widely-distributed granitoids. These ore-bearing granitoids typically belong to S-type or highly-fractionated I-type metaluminous-peraluminous calc-alkaline granitic magma series. The magma fractionation degrees are generally increased from those associated with skarn-type W deposits to those with veinlet-disseminated deposits. Crust materials played a key role in the formation of these W-mineralized granites, and also contributed to the various associated metals, such as W-Cu, W-Sn, W-Bi, W-Mo, and W-Be. According to the temporal-spatial association of W deposits with tectono-thermal events in South China, three metallogenic belts can be outlined for future exploration: Nanling W metallogenic Belt (NLB) (170–150 Ma), Eastern Yangtze W metallogenic Belt (EYB) (150–120 Ma), and Southeast Coast W metallogenic Belt (SCB) (120–80 Ma). According to the deep crustal structure features of these W metallogenic belts combined with characteristics of different W mineralization types, a generic model is proposed for the formation of the Mesozoic W deposits in South China. During the Mesozoic, from the southeast coast to the inland, the South China block experienced the west-toward subduction, retreating and conversion of the paleo-Pacific plate. Furthermore, deep faults in different areas enhance the local crust-mantle interaction, and W deposits types and temporal-spatial distribution of Mesozoic W deposits in different belts have good correspondence to the deep processes.

The Chuankou tungsten ore field, situated in the central area of the Qing-Hang ancient suture zone in South China, is characterized by predominantly quartz vein-type tungsten mineralization that formed near the contact between the Chuankou granite and slightly metamorphosed silt-bearing sericite slate. Based on field work, cathodoluminescence, molybdenite Re-Os dating and in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis, the Chuankou tungsten ore was formed at 230.6 ± 2.9 Ma to 229.4 ± 2.6 Ma in a typical Indosinian metallogenic event. In addition, three distinct generations of scheelite and two types of wolframite can be clearly distinguished. Type 1 wolframite has a semiautomorphic grain or brecciated vein structure with a high heavy rare earth element (HREE) content and an obvious negative Eu anomaly. Type 2 wolframite grains are strongly altered as residual-pseudomorphic structures by ore-forming fluids and have relatively low REE contents. Sch-1 scheelite is present in the interior of the type 2 wolframite grains. The Sch-1 scheelite grains have an elevated REE content and low 87Sr/86Sr ratios with a strongly negative Eu anomaly, which suggests an inheritance signal of the host rocks. Comparatively, Sch-2 and the altered Sch-1 scheelite have characteristic extremely low REE contents and remarkably strong positive Eu anomalies. These scheelites also have increased 87Sr/86Sr ratios and low 88Sr signals. Sch-3 is idiomorphic with perfect oscillating zoning. The REE content of Sch-3, which typically has the lowest 87Sr/86Sr ratios, is higher than those in Sch-1 and Sch-2, and the extremely high 88Sr signals indicate a distinct thermal fluid event that was directly derived from the host rock. The correlations between the REE and Nb of scheelite imply a type B-substitution of Sch-1 and Sch-2 but a type C-substitution for Sch-3. The correlation of EuN and EuN* shows an Eu3+ substitution process for stages Sch-1 and Sch-2 and an Eu2+ substitution process for stage Sch-3. Thus, we confirm that ore-bearing hydrothermal rocks must undergo early-stage metasomatism and filling, middle-stage fluid mixing between wall rocks and magmatic hydrothermal activity, and refilling of late-stage magmatic hydrothermal activity during the metallogenic process. During the Indosinian period, the mineralization stages of polymetallic deposits in the Indosinian were composed of Stage 1 (240 to 220 Ma) and Stage 2 (220 to 200 Ma). The Chuankou tungsten ore field can be considered as the typical representation of the Stage 1 metallogenic event in South China. This ore field is derived from remelting of the ancient basement and was reduced by regional extension under the dominant compression regime in the South China Block.

In the present paper, ten aqueous samples which contain-different concentrations of REE were collected in south Jiangxi province, and the reflectance spectra and the concentrations of REE were measured by analytical spectral devices (ASD) FieldSpec-3 reflectance spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results show that the spectra presented mix characteristics of pure water and rare earth oxide. In addition, six diagnostic absorption features caused by REE in visible and near-infrared wavelengths were detected. Then, relative absorption depths of the six absorption wavelength were calculated by the ratio spectra of sample spectra and pure water spectra. Finally, concentrations of total REE of ten samples and relative absorption depths of the six absorption wavelength were selected as two factors, and their relationship was perfectly described using linear regression analysis in which correlation coefficient was up to 96%-97%. The study provides a new method for quantitative estimation of different concentrations of dissolved REE in aqueous media, and strengthens theoretical basis for hyperspectral information extraction of REE.