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The Pulang ore deposit, one of the largest porphyry copper deposits in China, is located in the Yidun continental arc, SW China. The alteration zones in the deposit transit upward and outward from early potassium-silicate, through quartz–sericite, to later propylitization. The wallrock near the porphyry stock was mostly changed into hornfels. The former two alterations host the main orebodies, constituting the core of mineralized zone; the later two alterations only develop weak mineralization surrounding the core. In this paper, various fractal indices, including the exponent of lacunarity, multifractal spectrum, correlation dimension and Hurst exponent, are applied to characterize the Cu spatial distribution in 114 drillcores in the Pulang ore deposit, with the aim to correlate the element spatial pattern with its dynamic drive. Compared to fractal indices in the propylitic zone and hornfels, the exponents of lacunarity in the potassium-silicate and quartz–sericite zones exhibit lower and more stable values, the correlation dimensions are higher and more consistent; yet the values of height difference of multifractal spectrum are lower and largely varied, and the Hurst exponents show little difference. Variations of the former three indices suggest that the core of mineralized zone has more homogeneity, stronger compactness of high concentrations, and greater proportion of high concentrations in the Cu distribution compared to the other parts of the deposit. More importantly, the correlation dimension, indicating the complexity of controls underpinning the system, is closely correlated to the exponent of lacunarity, which represents the homogeneity of spatial pattern. This correlation between those two indices implies a genetic link, that is to say the greater complexity of controls results in a more homogeneous spatial distribution of Cu in the porphyry deposit. The stability of the two indices is considered to reflect the development of thick orebody, providing a new perspective to understand the genesis of porphyry ore deposit. This interpretation from the fractal perspective is consistent with the geological understanding for the formation of porphyry deposits, which is considered to be subject to the complexity of ore fluid evolution with multifaceted physicochemical conditions. For a pragmatic use, these two fractal indices are successfully applied in the delineation of the core of mineralized zone in the plane view. [ABSTRACT FROM AUTHOR]

The Beiya gold–polymetallic orefield, with gold reserves of 305 t, is one of the most representative porphyry-skarn orefields in the Jinshajiang–Ailaoshan Cu–Au ore belt within the Sanjiang region of southwest China. The orefield contains seven deposits: the Wandongshan, Hongnitang, Dashadi, Bijiashan, Weiganpo, Matouwan, and Bailiancun deposits. In this paper we report on the geochemistry and geochronology of porphyries associated with mineralization from the seven deposits. The results show that all the porphyries have similar geochemistry, with high alkalinity, high contents of SiO 2 , Al 2 O 3 , K 2 O, and Sr, high K 2 O/Na 2 O ratios, low MgO, Y, and Yb contents, enrichments in Ba, K, and Pb, depletions in P, Ti, Nb, and Ta, and non-evident to weak Eu depletions (δEu = 0.42–0.99). In the SiO 2 vs. Th/Ce diagram, the porphyry samples are distributed in the area of thickened lower crust, and in the Sr/Y vs. Y and La/Yb vs. Yb diagrams, the porphyries broadly followed the batch-melting trend of amphibolite containing up to 10% garnet. LA-MC-ICP-MS zircon U–Pb dating analysis suggests that the porphyries were emplaced between 34.62 ± 0.25 and 36.72 ± 0.25 Ma. They were coeval with lamprophyres (34 to 36 Ma) in the Beiya area and with potassic–ultrapotassic intrusive rocks (40 to 35 Ma) within the Jinshajiang–Ailaoshan magmatic belt, indicating possible genetic relation between these rock types. We suggest that the porphyries in the Beiya gold–polymetallic orefield were derived from the partial melting of a K-rich mafic source in the thickened lower crust, with the melting triggered by asthenospheric upwelling following the removal of lower lithospheric mantle. [ABSTRACT FROM AUTHOR]

Abstract: The Wandongshan gold poly-metallic deposit, one of the largest gold deposits in China, is composed of magmatic Fe–Au (M-FA), porphyry Cu–Au (P-CA), skarn-type poly-metallic (S-P) and laterite-type Fe–Au (L-FA) orebodies, manifesting complex multi-stage mineralizations. The vertical distributions of concentrations of ore-forming elements (Au, Ag, Cu, Pb and Zn) in 101 mineralized drillcores with various mineralization types are examined using self-affine fractal and multifractal models. The study reveals that the vertical distributions of element concentrations are controlled by ore type, geological position and spatial co-existence of multi-type mineralizations. Generally, element distributions in most drillcores dominated by M-FA orebodies exhibit higher Hurst exponent (H) and lower correlation dimension (D 2) than those dominated by P-CA or S-P orebodies, representing that the M-FA mineralization has a strong persistent element distribution and weak compact distribution of high element concentrations. This is likely due to the wide transportation of ore-bearing fluids and heterogeneous metal enrichment during formation of M-FA orebodies. Variations in mathematical parameters for M-FA dominated drillcores are strongly influenced by variations in geological positions and corresponding orebody shapes. High element concentrations are more compact mostly in contact areas than in distal Triassic carbonates. The spatial co-existence of multi-type mineralizations causes strong persistence of element distributions and weak compactness of high element concentrations. The correlations of D 2 for Au vs. Cu and Pb vs. Zn in M-FA dominated and L-FA drillcores are high, suggesting that Au and Cu have similar distribution patterns, and Pb and Zn have similar distributions. In P-CA and S-P orebodies, only Pb and Zn exhibit similar spatial distributions. [Copyright &y& Elsevier]

The article discusses research about muscovite, with an aim of understanding the geochronology of the Mahuaping W-Be deposit in Yunnan Province, China. It states that muscovite was cleaned using ultrasound and mass analysis was conduced using noble gas mass spectrometry. It is concluded that Mahuaping W-Be deposit was formed in the Late Eocene.

Highlights: [•] This study had produced four monoclonal antibodies against RDV. [•] Using the MAb, three serological methods were developed for RDV detection. [•] This study proved that RDV occurred in Yunnan Province of China. [ABSTRACT FROM AUTHOR]

Based on comprehensive petrological, geochronological, and geochemical studies, this study analyzed the relationships between the Beiya gold‐polymetallic skarn deposit and quartz syenite porphyries, and discussed the source(s) and evolution of magmas. Our results suggest that syenite porphyries (i.e. the Wandongshan, the Dashadi, and the Hongnitang porphyries), which formed between the Eocene and the early Oligocene epochs, are the sources for the gold‐polymetallic ores at the Beiya deposit. Carbonate rocks (T2b) of the Triassic Beiya Formation in the ore district provide favorable host space for deposit formation. Fold and fault structures collectively play an important role in ore formation. The contact zone between the porphyries and carbonates, the structurally fractured zone of carbonate and clastic rocks, and the zone with well‐developed fractures are the ideal locations for ore bodies. Four types of mineralization have been recognized: 1) porphyry‐style stockwork gold–iron (copper) ore, 2) skarn‐style gold‐iron (copper and lead) ore in the near contact zone, 3) strata‐bound, lense‐type lead–silver–gold ore in the outer contact zone, and 4) distal vein‐type gold–lead–silver ore. Supergene processes led to the formation of oxide ore, such as the weathered and accumulated gold–iron ore, the strata‐bound fracture oxide ore, and the structure‐controlled vein‐type ore. Most of these ore deposits are distributed along the axis of the depressed basin, with the hypogene ore controlling the shape and characteristics of the oxide ore. This study provides critical geology understanding for mineral prospecting scenarios. [ABSTRACT FROM AUTHOR]

Abstract: The Heqing area, located in the Sanjiang ore belt, China, consists of the Beiya gold orefield related to the alkaline porphyry, the Emeishan volcanic mafic rocks and a series of sedimentary rocks. Thirty-nine elements of stream sediment samples taken in the 1:200,000 geochemical survey in the Heqing area can be classified into four groups using principal component analysis. Two fractal models, i.e., the concentration–area model and the number–size model, are applied in determination of the thresholds for the representative elements in the four groups. The thresholds obtained from the two models are similar. According to the thresholds, the element concentration distribution can be divided into 3 segments, each of them is mainly correlated to one type of rocks, including the alkaline porphyry related to gold-mineralized rocks, mafic rocks and sedimentary rocks. This paper reveals that the various geological events can be characterized by the different fractal models of element distribution. [Copyright &y& Elsevier]