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Overprinting of an earlier formed deposit may obscure the nature of the deposit and hinder our understanding of regional metallogeny. The Qiaoxiahala Fe(-Cu/Au) deposit in eastern Junggar, NW China, is characterized by magnetite mineralization later replaced by sulfide minerals such as chalcopyrite. To reveal the genesis of Qiaoxiahala, we conducted Re-Os dating on post-magnetite molybdenite separated from chalcopyrite and rare earth elements (REEs) for basaltic volcanic rock, magnetite, chalcopyrite and diorite. An isochron age of 377±7 Ma was obtained together with a weighted mean age of 375±3 Ma, which is indistinguishable from mineralization ages determined in previous studies. Rare earth element (REE) data for basaltic volcanic rocks hosting the ore are comparable to that of the magnetite, while the REE signatures of chalcopyrite from the Cu ore and local intrusive diorite share a similar pattern. These suggest that two distinct fluid sources are responsible for the deposition of Fe and Cu in the Qiaoxiahala deposit. According to these experimental results, we consider that the iron mineralization in Qiaoxiahala is the result of fluid exsolution from basaltic volcanism which was further overprinted by fluids that deposited copper and gold, which may have been sourced from nearby dioritic intrusions.

The housing vacancy rate (HVR) is an important index in assessing the healthiness of residential real estate market. In China, it is hardly to take advantage of the basic data of real estate information due to the opaque of those data. In this paper, the HVR is estimated to two scales. At the grid level, urban area ratio was calculated by nighttime images after eliminating outliers of nighttime images and night light intensity of non-residential pixels in mixed pixels by a proposed modified optimal threshold method, and built-up areas in each pixel were extracted from the land-cover data. Then, the HVR is calculated by comparing the light intensity of specific grid with the light intensity of full occupancy rate regions. At the administrative scale, the GCI (‘ghost city’ index) is constructed by calculating the ratio of the total light radiation intensity of a city to the total construction land area of the city. The overall spatial differentiation pattern of the vacant houses in the national prefecture level administrative regions is analyzed. The following conclusions were drawn: vacant housing is rare in certain eastern coastal cities and regions in China with relatively fast economic development. Cities based on exhausted resources, some mountainous cities, and cities with relatively backward economic development more typically showed high levels of housing vacancy. The GCI of prefecture-level administrative units gradually declined from north to south, whereas the east-west distribution showed a parabolic shape. As city level decreased, the GCI registered a gradual upward trend. China’s urban housing vacancy can be divided into five categories: industry or resources driven, government planned, epitaxy expansionary, environmental constraint and speculative activate by combining the spatial distribution of housing vacancy with the factors of natural environment, social economic development level, and population density into consideration.

There are many Miocene collision- and subduction-related porphyry Cu deposits in the Eastern Tethyan orogenic belt. However, the petrogenesis of the ore-related magmas and the mechanism of metal enrichment remain controversial. Here, we present a geochemical study and comparison of the major Miocene ore-related porphyries and coeval ore-barren magmatic rocks in the Urumieh-Dokhtar magmatic arc in Iran and the Chagai belt in Pakistan, and the Eastern Gangdese belt of the Himalaya. The results show that ore-related porphyries are characterized by relatively depleted mean Sr isotopic compositions (0.704217–0.706859 in the Urumieh-Dokhtar magmatic arc; 0.705052–0.706588 in the Eastern Gangdese belt; 0.705252–0.706708 in the Chagai belt), but higher maximum Sr/Y ratios (40–149 in Urumieh-Dokhtar; 79–178 in Eastern Gangdese; 52–178 in Chagai). In contrast, the coeval ore-barren magmatic rocks yield relatively enriched, mean Sr isotopic compositions (0.704722–0.707653 in Urumieh-Dokhtar; 0.704701–0.707802 in Eastern Gangdese; 0.705982–0.707856 in Chagai), but lower maximum Sr/Y (2–88 in Urumieh-Dokhtar; 61–136 in Eastern Gangdese; and 19–35 in Chagai). A deep crustal hot zone model provides a robust explanation of these data. Melts derived from a deeper melt source in juvenile mafic lower crust, where mantle-derived materials are common, have a greater potential to yield a higher tonnage of metallic Cu, such as the Sar-Cheshmeh deposit in Iran, which is derived from a deep melt zone, and characterized by a low radioactive mean Sr isotopic value of 0.704851, but a huge tonnage of metallic Cu of 7.2 Mt and a high maximum Sr/Y value of 117 (representative of a deeper depth of the melt zone), whereas the Dalli deposit in Iran derived from a relatively shallow melt zone has a more radioactive mean Sr isotopic value of 0.706859, but a smaller amount of metallic Cu of 0.04 Mt and a lower maximum Sr/Y ratio of 40. Conversely, re-melting the contact between newly-formed and pre-existing crust where mantle-derived materials are absent will produce ore-barren rocks. Additionally, the ore-barren rocks with low Sr/Y ratios (

The newly discovered Katbasu gold deposit in the South Tianshan region has a gold reserve of 76 t at an average grade of 3.84 g/t. It is the first large gold deposit in the central segment of the South Tianshan. Gold mineralization is hosted within granite, and is associated with potassic, phyllic and chloritic alteration. Gold-bearing pyrite occurs as disseminations in the host rock and as quartz-sulfide veins cross-cutting the potassic and phyllic alteration assemblage. Rubidium (Rb) - strontium (Sr) analyses on sericite within five individual pyrite grains from a phyllic alteration sample yield an isochron age of 322.5 ± 6.8 Ma (MSWD = 3.2). The host granite has a SIMS U-Pb zircon age of 351.4 ± 1.1 Ma (MSWD = 0.13). The Rb-Sr isochron age represents the mineralizing age of the Katbasu gold deposit, which significantly postdates the ore-hosting granite but is consistent with the age of regional porphyry type mineralization at ~ 320 Ma in the South Tianshan. Discovery of the Katbasu gold deposits indicates huge potential for gold exploration in the central segment of the South Tianshan as it is geologically similar to the western and eastern segments of the South Tianshan, which both host many world-class gold deposits.

Porphyry copper deposits are the world's largest source of copper, but their ultimate source and deep process are disputed. We compare the Sr/Y ratios and Nd isotopes of coeval ore-bearing and ore-barren intermediate rocks from collisional and subduction settings to unravel the sourced depth and nature. During the Miocene mineralization epoch in the Iranian plateau, the median Sr/Y ratios and the median eNd(T) values of ore-bearing rocks (56 ± 38, 1.1 ± 1.5) are slightly higher than those of the ore-barren rocks (30 ± 31, −0.3 ± 2.4), respectively. Such patterns also exist at mineralization epochs during the Miocene collision in the eastern Gangdese, and the early Cretaceous subduction in Southeast China. These results indicate that all ore-bearing and ore-barren rocks are from the thickened (>1.2 Gpa) juvenile dominated (>70% mantle contribution) lower crust, and the ore-bearing rocks are sourced from slightly deeper and more juvenile sources compared to the coeval ore-barren rocks. The subtle geochemical difference but contrasting ore-potentials indicate heterogeneous origins, and the ore-bearing rocks may be related to ore-enriched sources at the lower crust. A deep crustal hot zone with melting at different depths with heterogeneous sources can account for such phenomena. Delamination of a thickened orogenic root induces asthenosphere upwelling and generates abnormal heat flow in the lower crust. The porphyry mineralization is an indication of the balancing between the melting of thickened lower crust and mantle upwelling, which explains the rarity of mineralization compared to the prolonged orogenic magmatism.

The Axi and Jingxi-Yelmand gold deposits, being the largest gold deposits in the Chinese North Tianshan, NW China, are located ca. l0 km apart in the Tulasu Basin, and are hosted by the Late Devonian - Early Carboniferous Dahalajunshan Formation. In situ LA-ICP-MS titanium analyses on quartz from the Axi and Jingxi-Yelmand deposits are broadly identical. Accordingly, the calculated ore-forming temperatures by Ti-in-quartz thermometer give average temperatures of 279 °C and 294 °C, respectively. Results of in situ SIMS analyses of oxygen and sulfur isotopes on quartz and pyrite from these two deposits are similar. Temperature-corrected fluids of the Axi deposit have δ 18 O values of 2.6–8.1‰ and δ 34 S values of 0.8–2.4‰, whereas the fluids of the Jingxi-Yelmand deposit have δ 18 O of 6.4–8.9‰ and δ 34 S of −0.4 to 4.0‰. The oxygen and sulfur isotopes from the two deposits indicate a magmatic origin. LA-ICP-MS zircon U-Pb ages of Aqialehe Formation sandstone provided a lower limit for the mineralization timing of the Axi deposit (288 Ma). In situ SIMS U-Pb analyses on entrapped zircon (297 Ma) and newly recognized 284.5 Ma columnar rhyolite implies that the Jingxi-Yelmand deposit formed in the Early Permian. Based on the magmatic affinity of the ore fluids, similar age and ore-formation temperatures, we propose that the Axi and Jingxi-Yelmand deposits comprise an epithermal gold system, which was driven by the same Permian magma in the Tulasu Basin. The ore geological features together with our new results indicate that the Axi and Jingxi-Yelmand deposits are intermediate and high sulfidation type epithermal deposits, respectively.

Accurate quantification of evaporation loss from irrigation canals at an irrigation district scale is very useful for developing efficient irrigation strategies, particularly in water-deficient regions. The double-deck surface air layer (DSAL) model, a new aerodynamic method proposed by Kobayashi et al. (2013), is used for estimating the evaporation loss from a running water surface in irrigation canals. In this study, based on the long-term meteorological measurements made at automatic weather stations in 2013 and the field experiment conducted at - midstream areas of the Heihe River Basin (HRB), northwestern China, the DSAL model was applied to estimate the long-term evaporation loss from irrigation canals, which was the remarkable highlight of the study. The results showed that the rate of evaporation from irrigation canals exhibited a concave-up trend for the period from June to September, with higher values in June and September (20 to 50 mm day&minus, 1) and lower values in July and August (around 10 mm day&minus, 1). During the four months, for the Yingke and Daman irrigation districts in the Zhangye Oasis, the total water losses from irrigation canals due to evaporation were approximately 23.9 &times, 105 m3 and 36.6 &times, 105 m3, or 3.2% and 4.8% of the total amount of irrigation water, respectively. Results of the study are not only important for improving the irrigation water use efficiency, but also are beneficial to develop sustainable water resource management in the midstream areas of the HRB.

Soil moisture and salinity are crucial parameters of the Earth&rsquo, s ecosystem, how to understand the radiation properties of them is of great significance for remote sensing monitoring. In this study, the application of mixed soil dielectric models (Dobson and generalized refractive mixing dielectric model (GRMDM)) and saline soil dielectric models (Dobson-S, HQR (Qingrong Hu), and WYR (Yueru Wu)) were analyzed to select the optimal models to simulate brightness temperature based on observational data. The brightness temperature of the soil moisture and multilevel salinity was simulated by using the Q-H (parameter of polarization mixing and parameter of characterizing height) model and Holmes parameterization scheme of soil effective temperature. The results show that both the Dobson model and the GRMDM model can well reproduce the real part and imaginary part of the dielectric constant of non-saline soil, and the GRMDM model was better. With the increase of the frequency, the simulation error of the dielectric constant of the saline soil by using the Dobson-S model, HQR model, and WYR model also increased, and the simulation result of the WYR model was better in the L band. The simulated result of the brightness temperature of soil moisture between the observation value and simulation value presented a high correlation both in the horizontal polarization and vertical polarization, with R greater than 0.967 and 0.948, and the root mean square error smaller than 3.998 K and 2.766 K, respectively. Meanwhile, the correlation coefficients of the brightness temperature of the saline soil in the horizontal polarization and vertical polarization were 0.935 and 0.971, and the root mean square errors were 5.808 K and 4.65 K, respectively. The brightness temperature decreased as the soil salinity increased, and the higher the salinity content was, the quicker the brightness temperature decreased. We expect that the experimental results can be used as a reference for algorithm developers to further enhance the accuracy of soil moisture and soil salinity retrievals.

Katbasu is a gold (and copper) deposit located in an arc on the southern margin of the Ili-Central Tianshan micro-continent. An in-situ method was conducted to acquire trace element concentrations to elucidate the origins and chemistry of the fluid in the Katbasu deposit. This included oxygen isotopes in quartz, as well as sulfur isotopes and trace elements concentrations in pyrite. Trace elements in gold deficient veins have higher concentrations compared to those in the gold bearing veins. The δ18O values of gold deficient veins are between 3.9 and 8.1‰, which imply a magmatic oxygen isotope signature. In contrast, oxygen isotopes in gold bearing veins range between −1.3 and 5.8‰, indicating the involvement of meteoric water in the mineralization system. This data, combined with evidence from alteration style and metal assemblages, shows that the ore-forming fluids at the Katbasu gold deposit is of a magmatic origin. The data also indicates that meteoric water diluted the magmatic fluid and caused an oversaturation of gold, causing precipitation of native gold grains. Trace elements in pyrite show no difference among the veins analyzed. However, they have distinctly different trace element patterns of pyrite from orogenic gold deposits. Based on the δ34S values of pyrite (8.3–12.9‰), and the lack of coeval regional metamorphism, we conclude that the enriched 34S at the Katbasu gold deposit is derived from a subducted slab during the Late Carboniferous.