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The Kaladawan Fe–Mo ore field in Altyn (Xinjiang Province, NW China) contains six Fe (–Mo) deposits, with total proven reserves of 60 Mt Fe and 10,000 t Mo. Tabular, lensoidal and stratiform orebodies occur in the Cambrian foliated marble, phyllite, carbonaceous slate, chlorite–sericite schist and quartz–sericite schist along the exocontact zone of the Kaladawan granite. Skarns are extensively developed and dominated by garnet, pyroxene, epidote, tremolite and actinolite, with minor chlorite, zoisite, quartz and calcite. Ore minerals are mainly magnetite and molybdenite. Five alteration and mineralization stages (I–V) were identified: the prograde (I) and retrograde (II) skarns are characterized by assemblages of garnet–pyroxene and epidote–tremolite–actinolite, respectively, intruded and replaced by mineral assemblages of magnetite–epidote–zoisite (III), quartz–sulfides (IV) and calcite–chlorite (V) in younging order. The Kaladawan garnet contains more andradite (61.2–94.4 mol%) than grossularite (37.5–5.0 mol%). Pyroxene is Mg-rich and Fe-poor, with an endmember range of 55.4–94.7 mol% diopside and 42.5–4.7 mol% hedenbergite. Amphibole comprises mainly tremolite and actinolite. The Kaladawan skarn mineral contents resemble typical skarn Fe and Mo deposits. In-situ LA-ICP-MS magnetite trace element analysis had identified unusually high Mg, Mo and Cr concentrations. The high Mo and the absence of molybdenite inclusions in magnetite suggest that the hydrothermal fluids may have been Mo-rich. The magnetite also contains similar (Ti + V) and (Al + Mn) values with typical skarn Fe deposits. Therefore, the Kaladawan Fe–Mo mineralization is best attributed to be skarn-type, and related to the Kaladawan granite intrusion. [ABSTRACT FROM AUTHOR]

Abstract: Principal component analysis (PCA) is employed to investigate the relationship between CO2 emissions (COEs) stemming from fossil fuel burning and cement manufacturing and their affecting factors. Eight affecting factors, namely, Population (P), Urban Population (UP); the Output Values of Primary Industry (PIOV), Secondary Industry (SIOV), and Tertiary Industry (TIOV); and the Proportions of Primary Industry's Output Value (PPIOV), Secondary Industry's Output Value (PSIOV), and Tertiary Industry's Output Value (PTIOV), are chosen. PCA is employed to eliminate the multicollinearity of the affecting factors. Two principal components, which can explain 92.86% of the variance of the eight affecting factors, are chosen as variables in the regression analysis. Ordinary least square regression is used to estimate multiple linear regression models, in which COEs and the principal components serve as dependent and independent variables, respectively. The results are given in the following. (1) Theoretically, the carbon intensities of PIOV, SIOV, and TIOV are 2573.4693, 552.7036, and 606.0791kt per one billion $, respectively. The incomplete statistical data, the different statistical standards, and the ideology of self sufficiency and peasantry appear to show that the carbon intensity of PIOV is higher than those of SIOV and TIOV in China. (2) PPIOV, PSIOV, and PTIOV influence the fluctuations of COE. The parameters of PPIOV, PSIOV, and PTIOV are ?2706946.7564, 2557300.5450, and 3924767.9807kt, respectively. As the economic structure of China is strongly tied to technology level, the period when PIOV plays the leading position is characterized by lagging technology and economic developing. Thus, the influence of PPIOV has a negative value. As the increase of PSIOV and PTIOV is always followed by technological innovation and economic development, PSIOV and PTIOV have the opposite influence. (3) The carbon intensities of P and UP are 1.1029 and 1.7862kt per thousand people, respectively. The carbon intensity of the rural population can be inferred to be lower than 1.1029kt per thousand people. The characteristics of poverty and the use of bio-energy in rural areas result in a carbon intensity of the rural population that is lower than that of P. [Copyright &y& Elsevier]

• Primary VMS and deformation-metamorphism overprints present at the Keketale Pb-Zn(-Ag) deposit. • Elements remobilized from parental grains re-precipitated as mineral inclusions and/or liberated. • Primary VMS S-Pb isotope signatures largely retained during deformation and metamorphism. The effects of post-VMS (volcanogenic massive sulfide) deformation/metamorphism on sulfide trace element and sulfur-lead isotopic compositions remain unclear. The greenschist to lower amphibolite facies metamorphosed Keketale VMS Pb-Zn(-Ag) deposit, located in the Devonian Maizi volcanic-sedimentary basin in the Chinese Altay, NW China, provides an opportunity to resolve the abovementioned issue. Two mineralization stages are recognized at Keketale, including (1) primary banded, massive and disseminated ores derived from sea-floor hydrothermal mineralization and (2) ore remobilization, as represented by intensively-deformed ores and quartz-polymetallic sulfide ore veins that crosscut the primary ores. Sulfide trace elements data suggest that Stage II pyrite and pyrrhotite have higher contents of Cu, Zn, Ag, Sb and Pb, whereas contents of these elements are higher in Stage I sphalerite and galena than their Stage II counterparts. Such elemental remobilization was probably caused by the rapid intragrain diffusion and subsequent fluid-mediated liberation with trace elements re-precipitated as particles within the same grain and nearby minerals, respectively. The δ34S CDT values in both stages show a trimodal distribution (−25.9 to −22.7‰, −17.0 to −10.6‰ and 0.6 to 2.1‰). Sulfide mineral pairs formed during primary VMS mineralization are not in sulfur isotopic equilibrium, and only localized re-equilibration occurs during deformation and metamorphism. In addition, the lead isotopic values of galena from remobilized sulfide veins overlap with those of the Stage I galena and pyrite. These data indicate that regional deformation and metamorphism of the Keketale deposit can be approximated as a closed system in terms of sulfur-lead isotopes. Whilst the presence of the anomalously low δ34S values (minimum −25.9‰) and the distinct lead isotopic ratios of sulfides from the calcite-quartz veins argue for that in the late part of the metamorphic event, some exotic lead and light sulfur were sourced from outside the ore field. In situ δ34S values of Stage I sulfides vary widely (−17.0 to +2.1‰), suggesting that the sulfur was originated from bacterial sulfate reduction (BSR) of marine sulfates with probably some magmatic input. Lead isotopes of the sulfides and mineralized meta-sedimentary-volcanic rocks display a linear distribution between the mantle and upper crust line in the 206Pb/204Pb vs. 207Pb/204Pb diagram. The lead source may be derived from both felsic volcanic rocks and mafic igneous rocks (and/or magmatic volatiles), and the sulfur-lead isotopes may result from a shallow-level seawater circulating process. An additional group of lead isotopic compositions of the meta-volcanic rocks show elevated present-day 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values, probably due to decay of Th and U carried by deeply-penetrative circulation (~13 km) of CO 2 -F-Cl-rich hydrothermal (metamorphic) fluids. Both syn-VMS shallow (seawater) and post-VMS deep (metamorphic fluids) circulation processes are critical for the metal concentration at Keketale. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three orders of ore-controlled faults with distinct occurrences were identified. • Their evolution and roles in orefluids migration and ores trap were clarified. • An updated paragenesis sequences related to structural evolution was established. • The southeast Fankou Zn-Pb deposit is a promising exploration target in future. The Fankou giant deposit (with exceeding 10 Mt Zn + Pb metals, grading at 15 wt%) is a carbonate-hosted, stratabound Zn-Pb deposit in the northern Quren Basin, South China. Lenticular, stratiform and wedge-shaped orebodies are strictly hosted in specific layers of Upper Devonian to Lower Carboniferous carbonate sequences along a series of NE and NNE trending faults. Previous ore geological and geochemical studies proposed that the Fankou can be analogous to a Mississippi Valley-type (MVT) deposit, but how the evolution of complex fault system controls ore-forming fluids migration, metals accumulation and orebodies localization remains unclear. To address this question, we conducted a deposit-scale structural analysis based on the geological mapping, underground works, and diamond drills logging. We identified three-order structures gradually growing in the Fankou deposit, including: 1) The first-order fault represented by F203 is a NW-striking thrust fault penetrating basement and acts as a major conduit for ultimate hydrothermal fluids migrations from depth; 2) The second-order faults include a spectrum of NNW-striking faults F2, F3, F4, F4, F5, F6, F7, F8 and F9. They are intersected with F203 in depth, and soon before and synchronous activities with Zn-Pb mineralization; 3) The third-order faults contain a series of NNE-striking F100, F101 and F102 with limited scale, which is subordinate to second-order faults and control the terminal localization of Zn-Pb orebodies. Collectively, we conclude that the evolutionary three groups of deposit-scale faults, derived from the regional NE-striking Wuchuan-Sihui Fault, jointly control the ore-forming fluids migrations from deep to shallow and from SE to NW in space. It is noteworthy that the second- to third-order faults act as the direct metal precipitation space when the upwards metalliferous fluids replaced with the favorable lithological layers. Therefore, we highlight that the southeast part of the mining area, where the metalliferous fluids came from, is a promising exploration target area in future. [ABSTRACT FROM AUTHOR]

• Stratiform "green rocks" are referred to as stratiform skarns. • Skarns are metasomatic products of magmatic instead of SEDEX fluids. • Skarns result from infiltration rather than contact metasomatism. • Stratabound Pb-Zn ore deposits in Fozichong belong to skarn-type. The Fozichong Pb-Zn ore district, located in the Yunkai Domain, southern section of the Qin-Hang Metallogenic Belt (QHMB) in South China, consists of several large-size stratabound ore deposits. The ore bodies are mainly stratiform and stratoid, bounded within the Ordovician and Silurian strata that are intruded by the Yanshanian porphyries. These deposits are debated between syngenetic sedimentary exhalative (SEDEX)- and epigenetic skarn-type. Since the occurrence of ore bodies is accompanied by the green-color stratiform rock (GSR), the GSR origin may play an important role to resolve the controversy. This motivates us to conduct a set of petrographic investigations, whole-rock and mineral chemistry analyses of the GSR coupled with zircon U–Pb geochronology of the intrusions. Detailed petrographic observations reveal that the GSR is mainly composed of a mineral assemblage of garnet, pyroxene, epidote, amphibole and chlorite, in analogy with that of traditional skarns. In addition, the concentrations of ore-related Pb, Zn, Cu and Ba consistently decrease from rim to core of an individual GSR layer, supporting an origin of hydrothermal fluid replacement rather than comparatively homogeneous sedimentation. Therefore, the Fozichong GSR is referred to as the stratiform skarn in literature. The Mn-poor and Ca-rich andradite, diopside-hedenbergite and calcic amphibole in the skarn provide robust evidence for the magmatic hydrothermal origin. The skarn is believed to be formed by the infiltration of magmatic hydrothermal fluids since it is not confined in the intrusion contact zone. Where the hydrothermal fluids derived from is complicated due to the multi-stages magmatic intrusions present in the district. Detailed investigations indicate that the late Yanshanian porphyries (zircon U–Pb dated at ~ 100 Ma, including dacite porphyry and granite porphyry) have a genetic link with the Fozichong skarn mineralization, while the Indosinian Dachong pluton and the early Yanshanian Guangping pluton exhibit insignificant correlation with the mineralization. The redox state of the skarn system changes from oxidation (prograde and retrograde stages) to reduction (late retrograde and quartz-sulfide stages), as recorded by the Fe2+/Fe3+ ratios in skarn minerals (i.e., 0.05 for garnet, 0.01–0.23 for amphibole and 55.6–178.1 for chlorite, respectively). During the redox transition, the mineralization has been developed with the precipitation of chlorite at moderate temperatures (~255 to 278 °C). In combined with the above analyses, the Fozichong is representative of a stratabound skarn Pb-Zn mineralization system in the Yunkai Domain, South China. [ABSTRACT FROM AUTHOR]