Hydrogeochemistry of porphyry related solutes in ground and surface waters; an example from the Casino Cu-Au-Mo deposit, Yukon, Canada

The Casino Cu-Au-Mo deposit is one of the largest and highest-grade porphyries of its kind in Canada, residing in an unglaciated region of west central Yukon. A batch of 22 stream water samples and eight groundwater samples were collected proximal to the deposit for the purpose of identifying the most diagnostic trace element and isotopic pathfinders associated with the hydrothermal mineralization, as well as establishing natural hydrogeochemical baselines for the area. Water chemistry around this deposit was investigated because: (i) the deposit has not yet been disturbed by mining; (ii) the deposit was known to have metal-rich waters in local streams; and (iii) the deposit has atypically preserved ore zones. Surface and ground waters around the Casino deposit are anomalous with respect to Cd (up to 5.4 µg/L), Co (up to 64 µg/L), Cu (up to 1657 µg/L), Mo (up to 25 µg/L), As (up to 17 µg/L), Re (up to 0.7 µg/L), and Zn (up to 354 µg/L) concentrations. Sulfur and Sr isotopes are consistent with proximal waters interacting with the Casino rocks and mineralization; a sulfide-rich bedrock sample from the deposit has δ34S = -1.2 ‰ and proximal groundwaters are only slightly heavier (-0.3 to 3.1 ‰). These geochemical and isotopic results indicate interaction and dispersion of porphyry related solutes in ground and surface waters and point to suitability of hydrogeochemistry as a medium for mineral exploration for porphyry-style mineralization in the Yukon, and elsewhere in Canada.Supplementary material: The physicochemical, major, trace, and isotopic data of stream and groundwaters used in this manuscript is publicly available as an Open File Report (OF 8823) from the Geological Survey of Canada.Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues

Epidote metasomatic zone in pegmatites from the vicinity of Strashimir Pb-Zn vein deposit, Central Rhodopes: mineralogy, geochemistry and in-situ U/Pb age determination

The epidote-group minerals are the major hydrothermal constituent, along with titanite, chlorite, quartz, and carbonates, developed in pegmatite on the contact with marble in the vicinity of Strashimir Pb-Zn vein deposit, Central Rhodopes. The U-Pb age of titanite (39.7±1.3 Ma) fixes the time of the hydrothermal mineralization. Trace element signatures of epidotes reveal minor REE-amounts, probably due to the concurrent growth of other REE-concentrating minerals (e.g. hydrothermal titanite).

A Combined EPMA and LA-ICP-MS Investigation on Bi-Cu-Au Mineralization from the Kizhnica Ore Field (Vardar Zone, Kosovo)

This paper describes a newly discovered Bi-Cu ± Au mineralization co-occurring with Pb-Zn-Ag hydrothermal mineralization within the Kizhnica-Hajvalia-Badovc ore field, central Kosovo, Vardar Zone. The mineralogy of two styles of Bi-Cu ± Au mineralization was described using EPMA in combination with reflected and transmitted light microscopy. Hydrothermal Cu-Bi veinlets in the Kizhnica andesite quarry consist of Bi sulfosalts (bismuthinite, cosalite, aikinite, and krupkaite), pyrite, hematite, chalcopyrite, galena, sphalerite, and tetrahedrite group minerals. Disseminated Bi-Au-Cu-Te mineralization from the contact type of mineralization (hornfels) consists of Bi sulfosalts (cannizzarite, bismuthinite, galenobismutite, cosalite), associated with sulfarsenides (arsenopyrite, gersdorffite, and cobaltite), base metal sulfides (chalcopyrite, pyrite, sphalerite, pyrrhotite, and galena), native gold, native bismuth, and tetradymite. LA-ICP-MS analyses of sphalerite, chalcopyrite, and tetrahedrite indicate increased content of In and Sn in the Kizhnica Bi-Cu-Au mineralizing system, while LA-ICP-MS analyses in pyrites show the presence of many elements, e.g., Au, As, Co, Sb, Tl, Hg, Pb, Bi related to the structure of pyrite or controlled by nano-inclusions. The results suggest a connection between Bi-Cu±Au mineralization and the proximity to intrusive rocks, which may be helpful for Au exploration in Kosovo.

A preliminary study on the element abundance in the Hulusimpang Formation, Way Kalianda, Pesawaran, Lampung, Indonesia

Hulusimpang Formation.has known as Oligocene-Miocene rocks that consisted of volcanoclastic rock. Its scope was wide, especially in southern Sumatra. This formation is supposed as a prospect host of various hydrothermal mineralization. A preliminary study was carried out to examine the abundance of elements located in Way Kalianda River, Pesawaran, Lampung. This study was conducted by easuring its stratigraphy and analyzing its composition using an X-Ray fluorescence analyzer. The lithologies generally consist of lapilli tuffs, volcanic breccias, interbeded by claystone and sandstone; in addition, it is also frequently found petrified wood and andesitic-lithic fragments. As a result, the significant abundant elements are Fe (35.5%), Si (27.9%), Al (17.4%), K (6.7%), Cl (5.5%), Ti (1.7%), and Ca (1.5%) and also Mn, Ag, P, Mg, Sr, Zr, and Co. It also presents trace elements such as Rb, Zn, Pb, Te, V, Ba, Cr, Sn, Ni, Ga, Nb, Mo, and Eu. These elements are suggested from distal facies of intermediates-magma series Tertiary volcano.

Magmatic-Hydrothermal Mineralization Processes at the Yidong Tin Deposit, South China: Insights from In Situ Chemical and Boron Isotope Changes of Tourmaline

Owing to the superimposition of water-rock interaction and external fluids, magmatic source signatures of ore-forming fluids for vein-type tin deposits are commonly overprinted. Hence, there is uncertainty regarding the involvement of magmatic fluids in mineralization processes within these deposits. Tourmaline is a common gangue mineral in Sn deposits and can crystallize from both the magmas and the hydrothermal fluids. We have therefore undertaken an in situ major, trace element, and B isotope study of tourmaline from the Yidong Sn deposit in South China to study the transition from late magmatic to hydrothermal mineralization. Six tourmaline types were identified: (1) early tourmaline (Tur-OE) and (2) late tourmaline (Tur-OL) in tourmaline-quartz orbicules from the Pingying granite, (3) early tourmaline (Tur-DE) and (4) late tourmaline (Tur-DL) in tourmaline-quartz dikelets in the granite, and (5 and 6) core (Tur-OC) and rim (Tur-OR), respectively of hydrothermal tourmaline from the Sn ores. Most of the tourmaline types belong to the alkali group and the schorl-dravite solid-solution series, but the different generations of magmatic and hydrothermal tourmaline are geochemically distinct. Key differences include the hundredfold enrichment of Sn in hydrothermal tourmaline compared to magmatic tourmaline, which indicates that hydrothermal fluids exsolving from the magma were highly enriched in Sn. Tourmaline from the Sn ores is enriched in Fe3+ compared to the hydrothermal tourmaline from the granite and displays trends of decreasing Al and increasing Fe content from core to rim, relating to the exchange vector Fe3+Al–1. This reflects oxidation of fluids during the interaction between hydrothermal fluids and the mafic-ultramafic wall rocks, which led to precipitation of cassiterite. The hydrothermal tourmaline has slightly higher δ11B values than the magmatic tourmaline (which reflects the metasedimentary source for the granite), but overall, the tourmaline from the ores has δ11B values similar to those from the granite, implying a magmatic origin for the ore-forming fluids. We identify five stages in the magmatic-hydrothermal evolution of the system that led to formation of the Sn ores in the Yidong deposit based on chemical and boron isotope changes of tourmaline: (1) emplacement of a B-rich, S-type granitic magma, (2) separation of an immiscible B-rich melt, (3) exsolution of an Sn-rich, reduced hydrothermal fluid, (4) migration of fluid into the country rocks, and (5) acid-consuming reactions with the surrounding mafic-ultramafic rocks and oxidation of the fluid, leading to cassiterite precipitation.

Mineral Associations of Veins with Quartz of the "Diamonds оf Donbass" Type in the Seleznevsky Coal-Bearing District (Folded Donbass)

The authors have established quartz and quartz-carbonate veins, the formation of which is associated with a low-temperature hydrothermal system of methane-water composition within the Seleznevsky coal-bearing region of the Folded Donbass. The article considers the features of localization of hydrothermal mineralization containing quartz with inclusions of hydrocarbons, and its potential ore content. It is established that the vein bodies are localized mainly in the near-hinge parts of the third-order brachianticlines in the central and marginal parts of the Seleznevskaya syncline. These veins form systems associated with the fracturing of the inter-layer stratification or intersecting the layers. Interplastic veins are subdivided into plate-like massive and vein-like bodies with a druze texture. The veins of the second type contain quartz crystals with hydrocarbon inclusions, referred to as "diamonds of Donbass". They form a paragenetic association with dickite. In addition, calcite in the form of short-prismatic crystals is a typical associated mineral in the vein bodies among limestone strata. In the veins among the sandstone layers, the association with goethite, oxides and hydroxides of manganese is developed. Two morphological types of cinnabar were found in the vein bodies on the basis of HMS sampling, the largest number is confined to the brachianticlines of the marginal parts of the Seleznevskaya syncline. The analysis of the results indicates the prospects for identifying mercury mineralization with quartz-dickite-cinnabar type of mineralization.