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Late Paleozoic granitoids, meta-granitoids and meta-volcanic rocks predominate in the metamorphic basement of the northern and western parts of the Sakar-Strandzha Zone (SASTZ) in southeast Bulgaria, together with subsidiaryTriassic rocks of the same nature. Generally, igneous minerals and textures are preserved, except the meta-granitoids and meta-volcanic rocks that experienced a low- to high-grade metamorphic overprint. The volcanic rocks have a peraluminous and high-K calc-alkaline composition, and the granitoids range between I- to S-type compositions, typical of volcanic arcs and syn-collisional settings. LILE and LREE-enrichment and Nb-Ta anomalies characterize the intrusive and extrusive rock suites. U-Pb zircon geochronology has yielded crystallization ages between 245 and 230 Ma for the majority of the studied igneous rocks, and between 297 and 281 Ma for a small group of igneous rocks. Early Permian and Middle Triassic igneous suites of the northern and western SASTZ have similar compositions and a similar tectonic setting when compared to Late Carboniferous-Early Permian intrusive and extrusive suites of the adjacent Sakar unit of the SASTZ, confirming a common regional late Paleozoic-early Mesozoic tectono-magmatic event. As the Late Carboniferous-Permian to Middle Triassic magmatic arc components extend across the SASTZ, they trace the time-correspondent active continental margin along the Eurasian plate during subduction of the Paleotethys oceanic lithosphere. The late Paleozoic Eurasian active continental margin magmatic arc evolution of the SASTZ can be linked with the Serbo-Macedonian-Rhodope zones to the southwest, where coeval meta-granitoids document the same geodynamic context. By contrast, the Triassic igneous suite of the SASTZ is unrelated to the Serbo-Macedonian-Rhodope zones, where Triassic meta-ophiolite and meta-granitoids record Neotethys rifting.

The average contents F = 788 ppm and Cl < 45 ppm of the clay fraction from Amazon River mouth sediments represent the composition of a large portion of weathered South American continental crust prior to any contact with high salinity formation waters. The data show a large fractionation between F and Cl with the latter being strongly leached during weathering along with Na and Ca. The one-order-of-magnitude fractionation is com- parable to Cl fractionation from degassing during early Earth accretion. In contrast, F is strongly retained in the hydroxyl sites of neoformed clay minerals, mainly illite, as well as in detrital apatite and muscovite. The high average ratio F/Cl > 10 of the clay fraction from Amazon River sediments are comparable only to Cl-poor MORB and evolved granite and rhyolite. The high content Cl = 180 ppm and low F/Cl = 3 of average shale is due to interaction of the sediments with high salinity diagenetic fluids. The Seridó schist belt is used to assess the behavior of F and Cl during shale metamorphism and anatexis. Its ratio F/Cl > 10 ppm is high compared to average shale and is related to the strong partitioning of Cl into metamorphic fluids. The obtained data suggest that the Cl partitioned into shales during diageneses is released back into fluids produced during metamorphic conditions. The experimental data indicate that anatexis of mica schist significantly fractionates F/Cl ratios producing schist residue with F/Cl > 38 and peraluminous melts with F/Cl = 6.

In Senegal, the environmental impact of artisanal small-scale gold mining (ASGM) using mercury (Hg) is poorly documented despite its intensification over the past two decades. We report here a complete dataset including the distribution and speciation of Hg in soil, sediment, and water in pristine and ASGM impacted sites of the Gambia River ecosystem (Kedougou region - eastern Senegal). Selective extraction showed that soils surrounding ASGM activities were contaminated with elemental Hg [Hg(0)] at concentrations up to 3.9 mg kg−1. In the Gambia River, high total Hg (THg: 1.16 ± 0.80 mg kg−1) and methylmercury (MeHg: 3.2 ± 2.3 ng g−1) were also measured in sediment samples collected at ASGM sites. Along the stream, THg concentrations in sediment decrease with distance from the ASGM sites, while those of methylmercury increase downstream. The study of THg and MeHg partitioning between filtered surface water and suspended particles demonstrate that particulate transport is responsible for the downstream dissemination of the Hg contamination from ASGM sites. Sedimentation of fine particles enriched in Hg downstream ASGM sites likely favors MeHg production and accumulation in sediment. Although elemental Hg is weakly labile, surface soil erosion may also provide important and long-term Hg inputs to downstream aquatic ecosystems, where it can be oxidized and methylated. Finally, the dissemination of THg and MeHg downstream from the ASGM sites in the Gambia River may constitute a long-term source of contamination and can have a large scale impact on the aquatic ecosystem through biomagnification.

Greece hosts a variety of magmatic-hydrothermal ore deposits/prospects with porphyry- and epithermal styles playing a major role in its total gold endowment. These deposit types are mainly clustered in two areas, the Rhodope- and Attico-Cycladic massifs, and formed from about 33 Ma to the Pleistocene, as a result of back-arc extension in the Aegean Sea, metamorphic core complex formation, and contemporaneous post-subduction and arc magmatism. In the Serbo-Macedonian massif, porphyry Cu-Au deposits include Skouries, Fisoka, Tsikara, Vathi and Gerakario. Causative intrusives are Oligocene to Miocene granodiorites to monzonites. Gold and PGE mineralization is associated with potassic alteration of the intrusives. In the eastern Rhodope massif and the NE Aegean islands, porphyry prospects occur at Pagoni Rachi, Konos Hill, Myli, Melitena (west Thrace), Fakos, Sardes, and Kaspakas (Limnos island) and Stypsi (Lesvos island). Mineralization is associated with Oligocene to Miocene subvolcanics of calc-alkaline to shoshonitic affinity. Feature of these prospects, which they share in common with several porphyry Au-only systems, is their shallow depth of emplacement, the presence of potassic/sodic-calcic and/or phyllic alteration, a strong epithermal overprint, their low Cu content, an extreme Re-enrichment, the multistage introduction of Au, the presence of banded quartz veinlets, and the local presence of tourmaline. New discoveries of porphyry-style mineralization at King Arthur, St. Philippos and Aisymi, increases the gold potential in west Thrace. High-intermediate sulfidation epithermal Au-Ag polymetallic deposits/prospects overprint and/or occur laterally from porphyry-style mineralization, where they are spatially associated with lithocaps of advanced argillic alteration. High-intermediate sulfidation Au-Ag epithermal mineralization at Perama Hill, Mavrokoryfi and Pefka in west Thrace, and at Pterounda, Mesotopos and Megala Therma on Lesvos island is controlled by steeply-dipping extensional faults within volcanic rocks, without any obvious genetic relationship to spatially-related porphyry-style mineralization. Polymetallic epithermal deposits and prospects contain critical and energy critical metals (e.g., Te, Se, Bi, Sb, In, Ge and Ga), which may be considered as by-products. In the Attico-Cycladic area, porphyry Mo-W mineralization occurs as sheeted quartz veins and stockworks cutting a potassic- to sericitic-altered Miocene granodiorite stock in the Lavrion district. Bonanza grade Au- and/or Ag-rich veins with epithermal affinities crosscut metamorphic rocks at Lavrion, and on Syros, Tinos, Antiparos and Anafi islands. Milos island is characterized by shallow submarine volcanic-hosted IS-HS epithermal Au-Ag-Te and base metal deposits. Antimony-As-Ag-Au deposits/prospects on Chios, Samos and Kos islands in the eastern Aegean Sea, indicate the potential for Carlin-style mineralization in Greece. Several factors played a role to the metal endowment of the Aegean porphyry-epithermal systems: magma fertility in the source regions, depth of emplacement of causative intrusives, relative contribution of mantle versus crustal material, redox state of subduction-related magmas, and physico-chemical fluid conditions at the site of ore deposition.

The magmatic arcs of the Eastern Pontides and Lesser Caucasus lie in continuation from one another. A comparison of the subduction related magmatic rocks outcropping throughout this segment of the Northern Tethyan belt exhibits chronological disparities, questioning the common subduction history of the Eastern Pontides and the Lesser Caucasus regions. New data and observations including geochronological and geochemical data, relative to subduction to collision related magmatic rocks argues a novel paleogeographic reconstruction illustrating Mesozoic and Cenozoic evolution of this region. Jurassic to Early Cretaceous arc magmatism runs mainly from the Sochi-Ritsa/Bechasyn regions (Greater Caucasus) towards the south-east to the Alaverdi region and further into the Lesser Caucasus. Late Cretaceous and Cenozoic arc magmatism is evidenced throughout the Eastern Pontides extending through the Bolnisi region to the Lesser Caucasus arc. East to west, Jurassic to Early Cretaceous and Late Cretaceous to Cenozoic portions of arc split to the north and south of the Eastern Black Sea, respectively. Throughout Cretaceous subduction, this segment of the magmatic arc of the Southern Eurasian margin was torn in two due to the oblique opening of the Eastern Black Sea as a back- to intra-arc basin, from west to east. This reconstitution implies that the Jurassic-Early Cretaceous subduction related magmatic rocks of the Greater Caucasus are remnant potions of the Eastern Pontides and Lesser Caucasus arcs. This infers the emplacement of subduction to collision related magmatic rocks throughout the Mesozoic and Cenozoic along the entire Southern Eurasian margin is solely due to a single long-lasting north-dipping subduction.

Palaeozoic granitoids and meta-granitoids dominate the metamorphic basement of the Sakar unit of the Sakar-Strandzha Zone (SASTZ) in southeast Bulgaria. In this article, we present new wholerock geochemical data and U–Pb zircon geochronology for the Sakar unit granitoids. The igneous minerals and textures are preserved, except the meta-granitoids that experienced a weak amphibolite-facies overprint. Geochemistry reveals compositions of peraluminous high-K calc-alkaline Ito S-type granitoids of volcanic arc origin. A major group of LILE-LREE-enriched granitoids and meta-granitoids and a single HFSE-HREE-enriched meta-granitoid are distinguished. U–Pb geochronology has yielded crystallization ages between 305 and 295 Ma for the major group granitoids and a ca. 462 Ma crystallization age of HFSE-HREE-enriched meta-granitoid. Late Palaeozoic granitoids of the Sakar unit show similar compositions and a similar tectonic setting when compared to other granitoids of the SASTZ, confirming a uniform region-wide tectonomagmatic event. As the Late Carboniferous-Permian magmatic arc components extend across the SASTZ, they trace the time-correspondent active continental margin along the Eurasian plate during subduction of the Palaeotethys oceanic lithosphere. The late Palaeozoic Eurasian active continental margin magmatic arc evolution of the SASTZ can be extended into the Serbo-Macedonian-Rhodope zones to the west, where time equivalent meta-granitoids support the same geodynamic context.

The composite Meghri-Ordubad pluton (MOP) is located in the southernmost Lesser Caucasus and outcrops over ~1000 km2 in southern Armenia and Nakhitchevan. It is characterized by nested intrusions incrementally emplaced over ~30 Myr from the Middle Eocene to Early Miocene, coeval with the closure of the Neotethyan Ocean and the regional Arabia-Eurasia continental collision. We recognize three compositionally distinct intrusive series in the MOP: a medium- to high-K calc-alkaline series 1 dominated by gabbro, quartz diorite and tonalite, a shoshonitic to high-K calc-alkaline series 2 including gabbro, monzogabbro, monzodiorite, monzonite and syenite, and a high-K calc-alkaline adakitic series 3 characterized by the emplacement of lamprophyre dikes followed by porphyritic granodioritic intrusions and dikes. Thermobarometry calculations together with detailed petrography, mineral chemistry and experimental mineral stability P-T diagrams indicate a polybaric crystallization history and magma emplacement at mid- to upper crustal levels (0.1-0.3 GPa). Mineral textures and compositions reveal open-system magmatic processes such as mafic magma replenishment and reactivation of crystal mushes prior to transport towards shallower crustal levels in the MOP. The evolution of magma chemistry (calc-alkaline vs shoshonitic) and mineral assemblages (amphibole-bearing vs amphibole-free) indicate fluctuation in primary melt alkali and water contents over time. Such chemical evolution is ascribed to a decrease in the degree of partial melting of a chemically heterogeneous, but isotopically homogeneous, mantle source. Overall, the MOP is characterized by the successive emplacement of hydrous magma batches in the mid- to upper crust and petrological processes that were dominated by fractional crystallization (± crustal assimilation) upon cooling and, or, decompression (± degassing). We propose a new temporal and spatial petrogenetic model for the MOP, encompassing three long-lived, chemically distinct magmatic series incrementally assembled over 30 Myr within a pre-, syn- and post-collisional geodynamic setting.

We modeled non-steady-state, fluid-assisted diffusion in a sheet plane, infinite cylinder and finite thin cylinder using analytical solutions of the diffusion equation and the experimental diffusivity of F-in-biotite. Diffusion experiments on natural biotite in the presence of hydrofluoric acid at 0.4 GPa and 650, 700, and 750 °C produced diffusive influx perpendicular to the c-axis. EPMA mapping and profiling allow us to define the following Arrhenius expression of F diffusion in biotite: D = 7.04 m 2 s × 10 − 4 × exp − 221 kJ mol RT − 1 The results yield the discrimination of a high-T homogenization domain where cooling paths continuously reequilibrate F-in-biotite, an intermediate-T zonation domain where cooling paths record F-in-biotite diffusion profiles and a low-T closure domain where F-in-biotite remains unchanged. The zonation domain significantly expands with increasing cooling rates and decreasing diffusion time. We systematically analyzed F-in-biotite with electron microprobe in samples collected along representative cross-sections within the Serido Belt, northeastern Brazil. Its metasedimentary units reached upper amphibolite grade metamorphic conditions, with constant F-in-biotite (F ≈ 0.33 wt.%) in grains from mica schist and paragneiss. The Ti-in-biotite geothermometer yielded nearly constant temperatures around 623 °C. The F-in-biotite regional background values remain unchanged at the contact with the major Ediacaran F-rich Acari pluton. It indicates the absence of magmatic fluid influx into the host rocks and is evidence for a fluid-absent nature of melts. By contrast, the F-in-biotite of the metric mica schist enclaves within dykes and sills of Cambrian pegmatitic granites was reequilibrated by interaction with exsolved fluids. The Ti-in-biotite geothermometer indicates temperatures around 642 °C, and our model suggests 100 kyr as a minimal duration for fluid-rock interaction. The preservation of intra-grain F-in-biotite homogeneity requires fluid flux cessation before cooling or fluid-present cooling rates below 100 °C Myr−1. Higher cooling rates would generate F-in-biotite intra-grain zonation. At the contact with the pegmatitic granites, the metasedimentary rocks show meter-scale F-in-biotite gradients due to thermal profiles setting the fluid (fH2O/fHF) gradient. The preservation of such gradients is related to a relatively fast fluid flux episode compared to the overall duration of the elevated thermal profile. The absence of intra-grain zonation indicates that F-in-biotite re-equilibration was fast relative to that of the fluid flux duration. We found intra-grain F-in-biotite zonation within an orthogneiss sample from the Paleoproterozoic Caico complex basement nearby the metasedimentary belt and intruded plutons. The fit of the natural profile by modeled profiles for cooling rates below 10 °C Myr−1, obtained from available Serido Belt U-Pb and 40Ar/39Ar ages, indicates that the orthogneiss cooled from 475 °C. It suggests the existence of a thermal gradient as the inner part of the belt cooled from 623 °C.

Three magmatic series of substantially different ages and compositions were successively emplaced to form the composite Meghri–Ordubab pluton (MOP) in the southernmost Lesser Caucasus. The protracted incremental assembly during 30 Myr, from Middle Eocene to Early Miocene, renders this location particularly suitable to characterize the petrogenetic evolution of Cenozoic magmatism during the final stage of the Neotethyan subduction. Based on whole-rock geochemistry, two main transitions tightly constrained in time are recognized. The first transition from Middle Eocene medium-K calc-alkaline to Late Eocene–Middle Oligocene shoshonitic magmatism corresponds to a marked increase in LREE and MREE and more juvenile 87 Sr/ 86 Sr and 143 Nd/ 144 Nd ratios. The second transition to Late Oligocene–Early Miocene high-K calc-alkaline “adakite-like” magmatism is coeval with a marked increase in Mg#, and Ni and Cr contents together with a depletion in MREE and HREE. Although the three differentiation series are derived from lower to mid-crustal hydrous magma fractionation, temporal variations of the magmatic source conditions are required to explain the contrasting chemistry of the parental magmas over time. Medium-K calc-alkaline parental magmas were generated by high degree of partial melting (~ 15%) of a garnet lherzolite. The shoshonitic and adakitic magmatic series represent magmas produced by low degree (1–5%) of partial melting of a garnet lherzolite, but a higher amount of residual garnet is required to reproduce the "adakite-like" signature. The timing of the two main geochemical transitions in the MOP is correlated with a progressive evolution from a compressional to an extensional stress regime linked to (1) the final stage of the Neotethyan subduction followed by the Arabia–Eurasia continental collision during the Eocene–Oligocene, and (2) the transition toward post-collisional magmatism, combined with a switch toward transcurrent tectonics during the Late Oligocene–Early Miocene.

We investigated the Sakar unit metamorphic rocks of the Sakar–Strandzha zone in Bulgaria, using 40Ar/39Ar dating of amphibole from the polymetamorphic basement and white mica in the overlying upper Permian metasedimentary rocks of the Paleokastro Formation. The amphibole and white mica revealed plateau ages of 140.50 ± 1.75 Ma and 126.19 ± 1.29 Ma, respectively, indicating an Early Cretaceous cooling history of the regional amphibolite-facies metamorphism to greenschist-facies conditions. Similar metamorphic grades and cooling histories of the Sakar unit share evidence with the nearby Rhodope Massif for the northern Aegean region-wide early Alpine tectonometamorphic event.

The Bolnisi district is a distinct tectonic zone of the Lesser Caucasus, which is considered to represent the eastern extremity of the Turkish Eastern Pontides. Late Cretaceous, low-K, calc-alkaline to high-K rhyolite of the Mashavera and Gasandami Suites is the predominant rock type of the district, and is accompanied by subsidiary dacite, and rare high-alumina basalt and trachyandesite of the Tandzia Suite. The Mashavera and Gasandami rhyolite and dacite have yielded U-Pb LA-ICP-MS and TIMS zircon ages between 87.14 ± 0.16 and 81.64 ± 0.94 Ma, which are in line with the Coniacan-Santonian ages of radiolarian fauna of the Mashavera Suite. The felsic rocks of the Mashavera and Gasandami Suites were deposited during a ~6.6 m.y.-long silicic magmatic flare-up event, which together with the Tandzia Suite mafic rocks, documents Late Cretaceous bimodal magmatism in an extensional tectonic setting. Trace element data indicate that high Y-Zr, low- to high-silica rhyolite and dacite, and low Y-Zr high-silica rhyolite have been erupted, respectively, from coeval deep and shallow crustal reservoirs. The rocks of the bimodal magmatic event are overlain by high-K volcanic rocks of the Campanian Shorsholeti Suite, which have been erupted during slab roll-back and steepening, from magmas produced by deep melting of a metasomatised mantle. Eocene postcollisional felsic intrusions crosscut the Late Cretaceous rock. The Coniacian to early Campanian bimodal magmatism, and the subsequent high-K magmatism of the Bolnisi district are contemporaneous and share geochemical characteristics with the Late Cretaceous magmatism of the Eastern Pontides. It documents the existence of a Late Cretaceous regional silicic magmatic province, and subsequent high-K magmatism during slab steepening. This regional magmatic evolution coincided with the opening of the Black Sea and the Adjara-Trialeti basins. This evolution was coeval with the wanning stages of northern Neotethyan subduction, after a ~40 m.y.-long magmatic lull along the southern Eurasian convergent margin. Early Eocene adakite-like magmatism affected both the Bolnisi district and the Eastern Pontides, demonstrating a common postcollisional magmatic evolution.

The PA +/- narbaAYA +/- Mo-Cu prospect is hosted within the PA +/- narbaAYA +/- intrusion, which is exposed together with the NW-SE-trending Koyunoba, Egrigoz, and Baklan plutons along the northeastern border of the Menderes massif. The PA +/- narbaAYA +/- intrusion predominantly comprises monzonite, porphyritic granite, and monzodiorite. All units of the PA +/- narbaAYA +/- intrusion have sharp intrusive contacts with each other. The principal mineralization style at the PA +/- narbaAYA +/- prospect is a porphyry-type Mo-Cu mineralization hosted predominantly by monzonite and porphyritic granite. The porphyry type Mo-Cu mineralization consists mostly of stockwork and NE- and EW-striking sub-vertical quartz veins. Stockwork-type quartz veins hosted by the upper parts of the porphyritic granite within the monzonite, are typically enriched in chalcopyrite, molybdenite, pyrite, and limonite. The late NE- and EW-striking normal faults cut the stockwork vein system and control the quartz-molybdenite-chalcopyrite-sphalerite-fahlore-galena veins, as well as molybdenite-hematite-bearing silicified zones. Lithogeochemical and whole-rock radiogenic isotope data (Sr, Nd and Pb) of the host rocks, together with Re-Os molybdenite ages (18.3 +/- 0.1 Ma - 18.2 +/- 0.1 Ma) reveal that the monzonitic and granitic rocks of the PA +/- narbaAYA +/- intrusion were derived from an enriched lithospheric mantle-lower crust during Oligo-Miocene post-collisional magmatism. The lithospheric mantle was metasomatised by fluids and subducted sediments, and the mantle-derived melts interacted with lower crust at 35-40 km depth. This mechanism explains the Mo and Cu enrichments of the PA +/- narbaAYA +/- intrusion during back-arc magmatism. We conclude that the melt of the PA +/- narbaAYA +/- intrusion could have rapidly ascended to mid-crustal levels, with only limited crustal assimilation along major trans-lithospheric faults as a result of thinning of the middle to upper crust during regional extension, and resulted in the development of porphyry-style mineralization during the early Miocene (similar to 18 Ma). The subsequent exhumation history of the Mo-Cu-bearing PA +/- narbaAYA +/- intrusion is attributed to regional-scale uplift, and further exhumation along detachment faults of the associated core complexes during the middle to late Miocene.

This study focuses on the Elbeyli-Ordu, Emeksen-Giresun, Guzelyayla-Trabzon and Uluta-Ispir porphyry-type prospects located in the Eastern Pontides, Turkey. Our new LA-ICP-MS U-Pb zircon age data reveal that the Elbeyli-Ordu Mo-Cu mineralization is hosted by a 77.0 +/- 1.3 Ma-old monzonite/monzodiorite with a shoshonitic character. The Emeksen Mo mineralization, located similar to 40 km southeast of the Elbeyli-Ordu prospect, consists of NW- and NE-striking quartz veins crosscutting a high-K calc-alkaline to shoshonitic granite dated at 78.5 +/- 0.8 Ma, a granodiorite dated at 78.7 +/- 05 Ma and porphyry granite dated at 77.7 +/- 0.5 Ma. The Guzelyayla porphyry Cu-Mo prospect consists of a stockwork-type Cu-Mo mineralization crosscutting a calc-alkaline 81.4 +/- 1.1 Ma-old dacite porphyry and Late Cretaceous calc-alkaline andesite. The Ispir-Ulutas mineralization is hosted within a highly sericitized 131.1 +/- 0.9 Ma-old quartz-porphyry that intruded into a 132.9 +/- 0.6 Ma-old calc-alkaline granite porphyry. Our new U-Pb zircon ages, lithogeochemical and radiogenic isotopic data of the host rocks associated with the porphyry-type prospects in the Eastern Pontides indicate that they formed in an arc-related environment during Cretaceous subduction of the Neotethys Ocean, and the Ispir-Ulutas prospect is attributed to the main stage of the northward subduction of the Neotethys during the Early Cretaceous. We conclude that the Guzelyayla and Emeksen hydrothermal systems were formed during a transitional compressional to extensional tectonic evolution, whereas the Late Cretaceous Elbeyli hydrothermal system was emplaced during an extensional arc magmatic event. Highly-oxidized, high-K calc-alkaline to shoshonitic magmas at Emeksen and Elbeyli were derived from a metasomatized, heterogeneous and enriched lithospheric mantle, with variable degrees of partial melting of the mantle wedge and variable crustal contamination. Mixing/mingling processes between mafic magmas derived from the lower crust and acidic magmas at upper crustal levels played an important role in the formation of Cu-Mo porphyry-type mineralization in the Eastern Pontides. (C) 2016 Elsevier B.V. All rights reserved.

The Shamlugh polymetallic deposit located in the Alaverdi mining district, Armenia is hosted by Middle Jurassic magmatic rocks of the Somkheto-Karabakh island arc, Lesser Caucasus. Lithogeochemistry and radiogenic isotope geochemistry indicate a subduction setting with an evolution from tholeitiic to transitional Middle Jurassic magmatism to calc-alkaline to high-K/shoshonitic Late Jurassic magmatism. A progressively more juvenile mantellic input in the magmatic source is noted. Ore consists of stratabound massive sulfide ore bodies, ore-bearing breccia, stockwork-style mineralization and disseminated ore hosted by a pyroclastic host rock unit below a subvolcanic rhyolitic sill. Towards depth, the stratabound ore is connected to subvertical high-grade sulfide veins hosted by basaltic andesitic, andesitic and dacitic tuff and lava breccia. Ore minerals include principally pyrite and chalcopyrite with minor sphalerite and hematite. Hydrothermal alteration consists of quartz, chlorite, carbonate and sericite in the footwall pyroclastic rock, tuff and lava breccia, which are also crosscut by late stage carbonate and barite veins. The rhyolitic sill has been affected by silicification and sericite alteration, and contains rare sulfides. Sulfur isotope values for sulfides range from +0.7 to +4.6 ‰, and suggest an essentially magmatic source for sulfur. Strontium isotopic compositions of hydrothermal carbonates and sulfates (0.70507 - 0.70660), sulfur isotopes of sulfates (+16.8 to +17.3 δ34S ‰ VCDT) and carbon and oxygen isotopic compositions of late stage carbonates (δ18O: +15.9 to +17.6 ‰ VSMOW; δ13C: -1.8 to -0.8 ‰ VPDB) are permissive with seawater incursion in the ore-forming hydrothermal system, but can also be attributed to fluid-rock interaction with hidden metamorphic basement rocks and Jurassic magmatic rocks. The lead isotopic composition of sulfides (206Pb/204Pb: 18.505 to 18.586, 207Pb/204Pb: 15.611 to 15.636, 208Pb/204Pb: 38.516 to 38.640) implies leaching of the Middle Jurassic host rocks as the main source of metals. LA-ICP-MS U-Pb zircon dating of the hanging wall rhyolitic sill affected by hydrothermal alteration yielded an age of 155.0 ± 1.0 Ma, and provides a maximum age for mineralization. Ore formation at Shamlugh is younger than the immediate Middle Jurassic host rocks and is related to the Late Jurassic calc-alkaline and high-K/shoshonitic magmatic evolution. Late Jurassic magmatism includes a tonalite dated by LA-ICP-MS U-Pb zircon geochronology at 152.9 ± 0.7 Ma that hosts the 146 Ma-old Teghout porphyry deposit. In the absence of other age constraints, the genetic relationship of the polymetallic Shamlugh deposit with the Teghout porphyry deposit remains open to question. Nevertheless, hydrothermal opaque mineral and alteration paragenesis, and the lithologically and structurally controlled ore body geometry at Shamlugh are consistent with a low to intermediate sulfidation epithermal model.

We focused on the Pirin–Pangeon–Thasos carbonate sequence of the Rhodope thrust system, combining Sr isotopes from marble with U–Pb dating of detrital zircons from interlayered schists with outcrop near the villages of Ilindentsi and Petrovo in Bulgaria. The youngest zircon age at Ilindentsi is 266 Ma, i.e. Middle Permian, while the youngest zircon at Petrovo yielded an age of 290 Ma, i.e. Early Permian. Strontium isotopes range from 0.707420 to 0.707653, and are consistent with a Middle Permian maximum depositional age. Middle Permian sedimentation of this carbonate platform most likely occurred along the Eurasian margin rather than the Gondwana margin.

We present field, chemical and U–Pb age data for metamafic–ultramafic bodies of the Triassic rift-related Therma–Volvi–Gomati (TVG) complex of the Serbo-Macedonian Massif (SMM) in the northern Aegean region. The TVG rocks record igneous textures overprinted by Alpine metamorphism and deformation. The high-Ti Volvi body was transformed into amphibolites, which also rim the low-Ti Gomati and Nea Roda bodies. The compositions are compatible with normal (N-) and enriched (E-) mid-ocean ridge basalt (MORB) and weak ocean island basalt (OIB) signatures of the high-Ti rocks, whereas the low-Ti rocks are depleted with respect to MORB, suggesting melt extraction from a mantle source. U–Pb geochronology reveals Triassic crystallization of the Volvi body at 240 Ma. Ordovician to Carboniferous xenocrystic zircons were found in the Stratoni body of the TVG complex, which were sampled from the SMM basement. The Triassic Arnea rift-related metagranite intrudes the Volvi body. Comparison of the compositions of the Volvi body and the Arnea metagranite of the SMM with Triassic metagranite of the Rhodope Massif (RM) supports the presence of a regional bimodal rift suite. The location of the TVG complex at the SMM–RM margin of Eurasia confirms its origin as a Middle Triassic rift suite, and its nature as a continental margin ophiolite representing an ocean–continent transition of the propagating Neotethys. Supplementary material: Whole-rock chemical analyses and U–Pb geochronology analytical results data tables are available at https://doi.org/10.6084/m9.figshare.c.4087022 Thematic collection: This article is part of the ‘Tethyan ophiolites and Tethyan seaways collection9 available at: https://www.lyellcollection.org/cc/tethyan-ophiolites-and-tethyan-seaways

Economically important porphyry Cu-Mo deposits (PCDs) are generally hosted by upper-crustal plutons of variable chemical compositions related to distinct geodynamic settings. The absolute timing and duration of pluton assembly and PCD formation are critical to understanding the genetic relationship between these interrelated processes. Here, we present new comprehensive zircon U-Pb and molybdenite Re-Os ages that tightly constrain the timing and duration of pluton assembly and the age of mineralization in one of the largest ore-bearing plutons of the central Tethyan metallogenic belt, the Meghri-Ordubad pluton, southern Armenia and Nakhitchevan, Lesser Caucasus. This composite pluton was incrementally assembled during three compositionally distinct magmatic episodes over ∼30 m.y., comprising Middle Eocene (48.9–43.1 Ma) calc-alkaline subduction-related magmatism lasting 5.8 ± 0.8 m.y., followed by postsubduction Late Eocene–Middle Oligocene (37.8–28.1 Ma) shoshonitic magmatism over 9.7 ± 0.9 m.y., and Late Oligocene–Early Miocene (26.6–21.2 Ma) adakitic magmatism consisting of shoshonitic dikes and high-K calc-alkaline granodioritic magmas emplaced over 5.4 ± 0.4 m.y. Despite the distinct geodynamic settings and magma compositions, each intrusive suite culminated in the formation of variably sized PCDs, including the giant Oligocene Kadjaran porphyry Cu-Mo deposit associated with high-Sr/Y shoshonitic magmas. Complementary in situ zircon hafnium (eHfzircon = +8 to +11.3) and oxygen (δ18Ozircon = +4.6‰ to +6.0‰) isotope data support a mantle-dominated magma source with limited crustal contribution and/or cannibalization of young and juvenile lower-crustal cumulates. We conclude that, independent of geodynamic setting and magma composition, long-lived (5–10 m.y.) incremental mantle-derived magmatism is a prerequisite to form fertile magmatic-hydrothermal systems, and especially giant PCDs.

The Konos Hill prospect in NE Greece represents a telescoped Mo⁻Cu⁻Re⁻Au porphyry occurrence overprinted by deep-level high-sulfidation mineralization. Porphyry-style mineralization is exposed in the deeper parts of the system and comprises quartz stockwork veins hosted in subvolcanic intrusions of granodioritic composition. Ore minerals include pyrite, molybdenite, chalcopyrite, and rheniite. In the upper part of the system, intense hydrothermal alteration resulted in the formation of a silicified zone and the development of various advanced argillic alteration assemblages, which are spatially related to N⁻S, NNW⁻SSE, and E⁻W trending faults. More distal and downwards, advanced argillic alteration gradually evolves into phyllic assemblages dominated by quartz and sericite. Zunyite, along with various amounts of quartz, alunite, aluminum phosphate⁻sulfate minerals (APS), diaspore, kaolinite, and minor pyrophyllite, are the main minerals in the advanced argillic alteration. Mineral-chemical analyses reveal significant variance in the SiO2, F, and Cl content of zunyite. Alunite supergroup minerals display a wide compositional range corresponding to members of the alunite, beudantite, and plumbogummite subgroups. Diaspore displays an almost stoichiometric composition. Mineralization in the lithocap consists of pyrite, enargite, tetrahedrite/tennantite, and colusite. Bulk ore analyses of mineralized samples show a relative enrichment in elements such as Se, Mo, and Bi, which supports a genetic link between the studied lithocap and the underlying Konos Hill porphyry-style mineralization. The occurrence of advanced argillic alteration assemblages along the N⁻S, NNW⁻SSE, and E⁻W trending faults suggests that highly acidic hydrothermal fluids were ascending into the lithocap environment. Zunyite, along with diaspore, pyrophyllite, and Sr- and Rare Earth Elements-bearing APS minerals, mark the proximity of the hypogene advanced argillic alteration zone to the porphyry environment.

Native iron has been identified in an active thermogenic travertine deposit, located at Ilia area (Euboea Island, Greece). The deposit is forming around a hot spring, which is part of a large active metallogenetic hydrothermal system depositing ore-bearing travertines. The native iron occurs in two shapes: nodules with diameter 0.4 and 0.45 cm, and angular grains with length up to tens of &mu, m. The travertine laminae around the spherical/ovoid nodules grow smoothly, and the angular grains are trapped inside the pores of the travertine. Their mineral-chemistry is ultra-pure, containing, other than Fe, only Mn (0.34&ndash, 0.38 wt.%) and Ni (&le, 0.05 wt.%). After evaluating all the possible environments where native iron has been reported up until today and taking under consideration all the available data concerning the study area, we propose two possible scenarios: (i) Ilia&rsquo, s native iron has a magmatic/hydrothermal origin i.e., it is a deep product near the magmatic chamber or a peripheral cooling igneous body that was transferred during the early stages of the geothermal field evolution, from high temperature, reduced gas-rich fluids and deposited along with other metals in permeable structural zones, at shallow levels. Later on, it was remobilized and mechanically transferred and precipitated at the Ilia&rsquo, s thermogenic travertine by the active lower temperatures geothermal fluids, (ii) the native iron at Ilia is remobilized from deep seated ophiolitic rocks, originated initially from reduced fluids during serpentinization processes, however, its mechanical transport seems less probable. The native iron mineral-chemistry, morphology and the presence of the other mineral phases in the same thermogenic travertine support both hypotheses.

Over > 40 years of implementation of the International Geoscience Programme (IGCP), a partnership and flagship programme between UNESCO and the International Union of Geological Sciences (IUGS), UNESCO realized that the involvement of Africa both in terms of projects devoted to the continent and leadership, was marginal. Between 2011 and 2013, UNESCO collaborated with the Swedish International Development Cooperation Agency (Sida) to support capacity-building activities aiming to increase the participation of Africa in IGCP. From this exercise, two projects (UNESCO/Sida IGCP-594 and IGCP-606) emerged as a research networking platform between scientists from Africa and Europe on the environmental and health challenges of mining activities in Africa. At the end of their implementation, the two projects jointly prepared and published a Special Issue on “Impacts of mining and mineral processing on the environment and human health in Africa” in the Journal of Geochemical Exploration in 2014 edited by Kříbek et al. (2014). However, it was obvious that the challenges facing African countries as a result of mining activities go well beyond simple IGCP projects, and need extensive mobilisation in terms of human re- sources, laboratory facilities and fund raising. The success of two major IGCP projects (IGCP-594 and IGCP-606) encouraged UNESCO to enter into a new Programme Cooperation Agreement with Sida for the period 2014–2018 to support an expanded project entitled “Mapping and Assessing the Environmental and Health Impacts of Abandoned Mines in Sub- Saharan African Countries”. The project aimed to reduce the adverse effects of mining activities on the ecosystem and health of adjacent communities while, at the same time, promote a peaceful mining atmosphere among industry, authorities and local communities. An important advancement in the mining sector is the legal ob- ligation for mining companies to rehabilitate former operational mine sites and ensure that they are restored to a safe environmental state after the mine is closed. While this concept is well rooted in mining legislation in many developed countries, this is not always the case in developing countries, especially in Sub-Saharan Africa. Apart from poor environmental governance as highlighted in the Africa Mining Vision, many African countries lack a precise inventory and assessment of abandoned and derelict mines. It is therefore important to make an assessment of the true extent of the detrimental effects of metal and metalloid pollutants and their impact on human and animal health, as well as on ecosystems. This is a pre-requisite for appropriate legislation development and enforcement. This new project intended to provide crucial scientific knowledge that will contribute to understanding of the factors that control cycling of pollutants from abandoned mines in soils, water and vegetation and the impact on the food chain. Development of appropriated technologies to mitigate environmental risk associated with mining activities was also at the heart of the project. Furthermore, influencing policies, training, education and awareness focusing on communities involved or living around mine sites were important aspects of the project. We anticipate that the results of the project will be used to improve the environmental norms in individual countries in Sub-Saharan Africa and the efficiency of governments in addressing the challenges related to the adverse effects of abandoned mines. The new project builds on a strong network of > 100 scientists working on 29 sites in 17 African countries, with focus on field assessment of pollution (soil, water, crops, health of human and animals), rehabilitation of degraded ecosystems, and policy issues for the attention of communities and governments. For the monitoring of the project, UNESCO put in place a scientific board composed of international experts in this field, some of whom have served as Co-Guest Editors of this Special Issue. An important meeting took place in April 2018 in Nairobi, Kenya, where all project leaders met with the members of the scientific board to evaluate the progress of the project. A key resolution by participants of this meeting was the preparation of another Special Issue to avail the new research contributions to the scientific community.

A detailed field and petrographic study constrains the volcanic evolution and environment setting of the volcano-sedimentary-hosted Chelopech Cu–Au epithermal deposit, Bulgaria. Magmatic activity and associated high-sulfidation epithermal mineralization occurred at about 91 Ma in the Panagyurishte ore district of the Eastern European Banat–Timok–Srednogorie metallogenic belt. Volcanic and hydrothermal activity took place in a complex subaqueous setting, resulting in the intercalation of quartz sandstone with andesitic volcanic and volcaniclastic breccia. There are also hypabyssal andesite intrusion, phreatomagmatic breccia and interbeds of pyroclastic, oolithic and bioclastic rocks. The presence of altered cerebroid ooid-bearing sedimentary units characteristic of salty environment is in accordance with a lagoon environment predating the mineralization at Chelopech. Four principal stages of evolution for the Chelopech district are proposed based on field and petrographic observations. Initial volcanism occurred in a lake or in a coastal, shallow lagoon environment above crystalline basement. The Chelopech “phreatomagmatic” breccia and subsurface andesites were emplaced at this time. Subsequent hydrothermal activity produced the different hydrothermal breccia types, advanced argillic and quartz–phyllic alteration, and Au–Cu vein and replacement mineralization. The end of volcanism and hydrothermal activity was associated with opening of a pull-apart basin that covered the Chelopech environment with a sedimentary flysch. Tertiary compression faulting juxtaposed various rocks and tilted the ore deposit during the Alpine orogeny.

The polymetallic Cu–Au–Ag–Zn ± Pb, Cu–Au and Cu deposits in the Kapan, Alaverdi and Mehmana mining districts of Armenia and the Nagorno–Karabakh region form part of the Tethyan belt. They are hosted by Middle Jurassic rocks of the Lesser Caucasus paleo-island arc, which can be divided into the Kapan Zone and the Somkheto–Karabakh Island Arc. Mineralization in Middle Jurassic rocks of this paleo-island arc domain formed during the first of three recognized Mesozoic to Cenozoic metallogenic epochs. The Middle Jurassic to Early Cretaceous metallogenic epoch comprises porphyry Cu, skarn and epithermal deposits related to Late Jurassic and Early Cretaceous intrusions. The second and third metallogenic epochs of the Lesser Caucasus are represented by Late Cretaceous volcanogenic massive sulfide (VMS) deposits with transitional features towards epithermal mineralization and by Eocene to Miocene world-class porphyry Mo–Cu and epithermal precious metal deposits, respectively. The ore deposits in the Kapan, Alaverdi and Mehmana mining districts are poorly understood and previous researchers named them as copper–pyrite, Cu–Au or polymetallic deposits. Different genetic origins were proposed for their formation, including VMS and porphyry-related scenarios. The ore deposits in the Kapan, Alaverdi and Mehmana mining districts are characterized by diverse mineralization styles, which include polymetallic veins, massive stratiform replacement ore bodies at lithological contacts, and stockwork style mineralization. Sericitic, argillic and advanced argillic alteration assemblages are widespread in the deposits which have intermediate to high-sulfidation state mineral parageneses that consist of tennantite–tetrahedrite plus chalcopyrite and enargite–luzonite–colusite, respectively. The ore deposits are spatially associated with differentiated calc-alkaline intrusions and pebble dykes are widespread. Published δ 34 S values for sulfides and sulfates are in agreement with a magmatic source for the bulk sulfur whereas published δ 34 S values of sulfate minerals partly overlap with the isotopic composition of contemporaneous seawater. Published mineralization ages demonstrate discrete ore forming pulses from Middle Jurassic to the Late Jurassic–Early Cretaceous boundary, indicating time gaps of 5 to 20 m.y. in between the partly subaqueous deposition of the host rocks and the epigenetic mineralization. Most of the described characteristics indicate an intrusion-related origin for the ore deposits in Middle Jurassic rocks of the Lesser Caucasus, whereas a hybrid VMS–epithermal–porphyry scenario might apply for deposits with both VMS- and intrusion-related features. The volcanic Middle Jurassic host rocks for mineralization and Middle to Late Jurassic intrusive rocks from the Somkheto–Karabakh Island Arc and the Kapan Zone show typical subduction-related calc-alkaline signature. They are enriched in LILE such as K, Rb and Ba and show negative anomalies in HFSE such as Nb and Ta. The ubiquitous presence of amphibole in Middle Jurassic volcanic rocks reflects magmas with high water contents. Flat REE patterns ([La/Yb] N = 0.89–1.23) indicate a depleted mantle source, and concave-upward (listric-shaped) MREE–HREE patterns ([Dy/Yb] N = 0.75–1.21) suggest melting from a shallow mantle reservoir. Similar trace element patterns of Middle Jurassic rocks from the Somkheto–Karabakh Island Arc and the Kapan Zone indicate that these two tectonic units form part of one discontinuous segmented arc. Similar petrogenetic and ore-forming processes operated along its axis and Middle Jurassic volcanic and volcanosedimentary rocks constitute the preferential host for polymetallic Cu–Au–Ag–Zn ± Pb, Cu–Au and Cu mineralization, both in the Somkheto–Karabakh Island Arc and the Kapan Zone.

This study describes Hg-resistant bacterial present in the aquatic sediments artisanal small-scale gold mining ASGM activities along Gambia River Kedougou, Senegal. Mercury (Hg) is used for gold amalgamation in artisanal small-scale gold mining (ASGM) activities. The level of total Hg in sediment samples was determined by automatic mercury analyser. Bacterial (colony-forming units) susceptibility to Hg was evaluated by minimal inhibitory concentrations. The phylogenetic diversity analysis of the Hg-resistant bacteria was performed by PCR amplification of 16S rDNA on isolated bacterial strains, followed by restriction fragment length polymorphism, cloning and sequencing. The results documented high concentrations of Hg in ASGM activity areas ranging from 2.4 to 6.2 mg kg-1. Population densities of heterotrophic bacteria in wet sediment ranging from 3.7 × 106 to 4.6 × 108 CFU g−1. The isolated bacterial strains from highly Hg-contaminated sites can grow to medium containing up to 17 mg L−1 of Hg2+. In this study, bacterial strains resistant to Hg are Stenotrophomonas maltophilia, Dyella ginsengisoli, Arthrobacter defluvi, Arthrobacter pascens, Bacillus firmus and Pseudomonas moraviensis. Our results demonstrate the occurrence the presence of diverse groups of bacterial strains resistant to metal (Hg) under tropical conditions. The isolated strains are particularly interesting for further studies to evaluate their role in bioremediation of Hg in contaminated aquatic ecosystems.

Field, geochemical, and geochronologic data of high-grade basement metamafic and evolved rocks are used to identify the nature and timing of pre-Alpine crustal growth of the Rhodope Massif. These rocks occur intrusive into clastic-carbonate metasedimentary succession. Petrography and mineral chemistry show compositions consistent with Alpine amphibolite-facies metamorphism that obliterated the original igneous textures of the protoliths. Bulk-rock geochemistry identifies low-Ti tholeiitic to calc-alkaline gabbroic-basaltic and plagiogranite precursors, with MORB-IAT supra-subduction zone signature and trace elements comparable to modern back-arc basalts. The U-Pb zircon dating revealed a mean age of 455 Ma for the magmatic crystallization of the protoliths that contain inherited Cambrian (528–534 Ma) zircons. Carboniferous, Jurassic, and Eocene metamorphic events overprinted the Ordovician protoliths. The radiometric results of the metamorphic rocks demonstrate that Ordovician oceanic crust was involved in the build-up of the Rhodope high-grade basement. Dating of Eocene-Oligocene volcanic rocks overlying or cross-cutting the metamorphic rocks supplied Neoproterozoic, Ordovician and Permo-Carboniferous xenocrystic zircons that were sampled en route to the surface from the basement. The volcanic rocks thus confirm sub-regionally present Neoproterozoic and Paleozoic igneous and metamorphic basement. We interpret the origin of the Middle-Late Ordovician oceanic magmatism in a back-arc rift-spreading center propagating along peri-Gondwanan Cadomian basement terrane related to the Rheic Ocean widening. The results highlight the presence of elements of Cadomian northern Gondwana margin in the high-grade basement and record of Rheic Ocean evolution. The eastern Rhodope Massif high-grade basement compared to adjacent terranes with Neoproterozoic and Cambro-Ordovician evolution shares analogous tectono-magmatic record providing a linkage among basement terranes incorporated in the Alpine belt of the north Aegean region.

Heating of quartz crystals in order to study melt and high-temperature fluid inclusions is a common practice to constrain major physical and chemical parameters of magmatic and hydrothermal processes. Diffusion and modification of trace element content in quartz and its hosted melt inclusions have been investigated through step-heating experiments of both matrix-free quartz crystals and quartz crystals associated with sulfides and other minerals using a Linkam TS1500 stage. Magmatic and hydrothermal quartz were successively analyzed after each heating step for Cu, Al, and Ti using electron probe micro-analyzer. After the last heating step, quartz crystals and their hosted melt inclusions were analyzed by laser ablation inductively coupled plasma mass spectrometry and compared to unheated samples. Heated samples reveal modification of Cu, Li, Na, and B contents in quartz and modification of Cu, Li, Ag, and K concentrations in melt inclusions. Our results show that different mechanisms of Cu, Li, and Na incorporation occur in magmatic and hydrothermal quartz. Heated magmatic quartz records only small, up to a few ppm, enrichment in Cu and Na, mostly substituting for Li. By contrast, heated hydrothermal quartz shows enrichment up to several hundreds of ppm in Cu, Li, and Na, which substitute for originally present H. This study reveals that the composition of both quartz and its hosted melt inclusions may be significantly modified upon heating experiments, leading to erroneous quantification of elemental concentrations. In addition, each quartz crystal also becomes significantly enriched in Cu in the sub-surface layer during heating. We propose that sub-surface Cu enrichment is a direct indication of Cu diffusion in quartz externally sourced from both the surrounding sulfides as well as the copper pins belonging to the heating device. Our study shows that the chemical compositions of both heated quartz and its hosted inclusions must be interpreted with great caution to avoid misleading geological interpretations.

The ophiolitic rocks of the Attic-Cycladic crystalline belt are considered of key importance for understanding the Mesozoic tectonic evolution of the Aegean region. Unresolved questions concern their tectono-stratigraphic relationships across the region. The mode of occurrence of the Cycladic ophiolites varies, as they appear as: (a) dismembered blocks (olistoliths) within the supra-detachment units of Paros and Naxos; (b) mélange formations in the upper structural unit of western Samos and Skyros; and (c) meta-ophiolitic mélange in the Cycladic Blueschist Unit (CBU) from central Samos. The trace element geochemistry and Pb-Sr-Nd isotopes of the mafic ophiolitic rocks indicate four geochemical groups: (a) the upper unit metabasites from Paros and western Samos (Kallithea) display an evolved basaltic composition (Mg# 40.2–59.6), with low Zr/Nb values (5–16) and high Ce/Y values (1.3 to 2.6) compared to MORB, indicating island-arc tholeiite affinities; (b) Naxos upper unit metabasalts show spider diagrams patterns indicating ocean island basalt (OIB-type) affinities; (c) Central Samos metagabbros (CBU) are primitive rocks with Back-Arc Basin basalt affinities; (d) the Skyros metadolerites and Tinos (Mt Tsiknias) and S. Evia (CBU) metagabbros, cluster as a separate geochemical group; they exhibit high MgO values (>10 wt %), very low TiO2 values (0.1–0.2 wt %), Y and Yb, and depleted trace element N-MORB normalized patterns, similar to volcanic rocks formed in modern oceanic fore-arc settings, such as boninites. A combination of the Pb- and Sr-isotopic compositions of Cycladic metabasites indicate that the Pb and Sr incorporated in the Cycladic ophiolites correspond to mixtures of magmatic fluids with seawater (206Pb/204Pb = 18.51–18.80; 207Pb/204Pb = 15.59–15.7; 208Pb/204Pb = 39.03–39.80 and initial 87Sr/86Sr80 = 0.705–0.707). Furthermore, peridotite relicts from Samos, Paros, and Naxos—irrespective of the structural unit—display chemical affinities of ocean floor peridotites formed in a supra-subduction zone. The characteristics of harzburgite relicts in Cycladic serpentinites and Skyros indicate a highly residual nature of the mantle source. Geochemical data from this study shed further light on the complex structure of the oceanic lithosphere from which the Cycladic ophiolites originated.

The Lac Herbin deposit consists of a network of mineralized, parallel steep-reverse faults within the synvolcanic Bourlamaque granodiorite batholith at Val-d’Or in the Archean Abitibi greenstone belt. There are two related quartz-tourmaline-carbonate fault-fill vein sets in the faults, which consist of subvertical fault-fill veins associated with subhorizontal veins. The paragenetic sequence is characterized by a main vein filling ore stage including quartz, tourmaline, carbonate, and pyrite-hosted gold, chalcopyrite, tellurides, pyrrhotite, and cubanite inclusions. Most of the gold is located in fractures in deformed pyrite and quartz in equilibrium with chalcopyrite and carbonates, with local pyrrhotite, sphalerite, galena, cobaltite, pyrite, or tellurides. Petrography and microthermometry on quartz from the main vein filling ore stage reveal the presence of three unrelated fluid inclusion types: (1) gold-bearing aqueous-carbonic inclusions arranged in three-dimensional intragranular clusters in quartz crystals responsible for the main vein filling stage, (2) barren high-temperature, aqueous, moderately saline inclusions observed in healed fractures, postdating the aqueous-carbonic inclusions, and considered as a remobilizing agent of earlier precipitated gold in late fractures, and (3) barren low-temperature, aqueous, high saline inclusions in healed fractures, similar to the crustal brines reported throughout the Canadian Shield and considered to be unrelated to the gold mineralization. At the Lac Herbin deposit, the aqueous-carbonic inclusions are interpreted to have formed first and to represent the gold-bearing fluid, which were generated contemporaneous with regional greenschist facies metamorphism. In contrast, the high-temperature aqueous fluid dissolved gold from the main vein filling ore stage transported and reprecipitated it in late fractures during a subsequent local thermal event.

The Pagoni Rachi/Kirki Cu-Mo ± Re ± Au deposit is a telescoped porphyry-epithermal system that contains molybdenite with up to 4.7 wt.% Re and the rare mineral rheniite (ReS2). The deposit is spatially related to an Oligocene, calc-alkaline hornblende-biotite- bearing granodiorite-tonalite porphyry stock; however, a genetic link to a buried stock of quartz-feldspar porphyry magma beneath Pagoni Rachi cannot be excluded. Alteration types and vein relationships suggest that mineralization can be divided into four paragenetic stages, which are, from early to late: (1) sodic/potassic-calcic alteration with quartz- and magnetite-bearing veins (A- and M-type) and distal propylitic alteration, (2) sodic/potassic alteration with quartz-pyrite-chalcopyrite-molybdenite veins (B-type), (3) sericitic alteration with “transitional” porphyry to epithermal pyrite-chalcopyrite-molybdenite veins (D-type), and (4) argillic alteration with quartz-calcite base metal and precious metal rich veins (E-type) with epithermal affinity. Bulk ore analyses and mineralogical data are consistent with deposition of precious metals in all mineralization stages: electrum in A- and M-type veins is spatially associated with bornite and chalcopyrite, whereas tellurides (cuprian hessite, stutzite, petzite) and Ag-Au alloy occur in the epithermal veins. The D-type veins contain the highest gold grades (up to 5 g/t) and include Ag-, Bi-, Te-, and Se-bearing minerals indicating a possible genetic relationship with E-type epithermal veins. Fluid inclusion data indicate that A- and B-type veins (porphyry style mineralization) were deposited at 360–510 °C and at pressures up to 690 bars ( 74 wt.% NaCl equiv.) fluids. Subsequent dilution of the moderately saline fluid formed a lower temperature (210–340 °C), less saline (1.4–2.9 wt.% NaCl equiv.) fluid in late epithermal E-veins. Based on the Au and Re grades, Cu/Mo ratios, presence of rheniite and the extremely high Re content of molybdenite, Pagoni Rachi may be considered as a distinct class of porphyry deposits, a Cu-Mo±Re±Au system that is derived from rocks transitional between calc-alkalic and alkalic porphyries. Its similarity with other Re-Au enriched porphyry-style deposits in northeastern Greece indicates that this area may represent a new Au-Re-Te metallogenetic province.

The Kapan Zone in southern Armenia is a Middle Jurassic to Upper Cretaceous island-arc domain at the southern margin of Eurasia that collided with the Gondwana-derived South-Armenian Block in the Upper Cretaceous–Paleocene. Igneous rocks of Middle Jurassic to Quaternary age record the geodynamic evolution of the Kapan Zone, whose tectonic setting changed from an active arc environment, related to the northeastwards subduction of the Neotethys, to a post-collisional setting. U–Pb zircon ages of intrusive rocks from the Kapan Zone confirm the division of the stratigraphic column into the Middle Jurassic, Upper Jurassic–Lower Cretaceous and Paleogene magmatic complexes. Middle Jurassic tonalite was sampled from pebble dykes and dated at 165.6 ± 1.4 Ma, voluminous plutons intruded in the Kapan Zone between 137.7 ± 1.6 Ma and 131.5 ± 2.1 Ma within a time span of less than 10 Ma and Paleogene gabbro was dated at 50.82 ± 0.51 Ma. Volcanic rocks in the Kapan Zone range from basaltic to rhyolitic composition with andesite being the most common rock type. Intrusive and volcanic rocks from the three magmatic complexes and Quaternary basanite have subduction-related signatures. They are enriched in fluid-mobile LILE such as K, Rb and Ba and are depleted in HFSE such as Zr, Nb and Ta, which suggest their derivation from a metasomatized mantle source as old crustal material is virtually absent in the Kapan Zone. The subduction-related signature is conserved in post-collisional rocks from the Paleogene magmatic complex and the Quaternary basanite, indicating their origin from a mantle source which was metasomatized during preceding subduction. REE patterns from igneous rocks of the Kapan Zone are characterized by increased slope in younger rocks. Flat patterns in Middle Jurassic rocks indicate melting from a depleted mantle reservoir whereas REE patterns with increased slope in rocks from the Upper Jurassic–Lower Cretaceous magmatic complex, the Paleogene magmatic complex and the Quaternary basanite suggest either smaller amounts of partial melting and/or input of less depleted mantle material in the source region. The initial isotopic signature of rocks from the Kapan Zone supports melting of a primitive mantle source with limited contribution of assimilated crustal material. The more crustal isotopic signature of rocks from the Middle Jurassic and Paleogene magmatic complexes relative to rocks from the Upper Jurassic–Lower Cretaceous magmatic complex indicates subduction of continent-derived sedimentary material and interaction with old basement units at depth. Reported coeval subduction-related Middle Jurassic to Cretaceous intrusive and volcanic rocks from the Sanandaj–Sirjan Zone in Iran are in good agreement with our results from the Kapan Zone in southern Armenia. This suggests a continuation of the magmatic arc of the Lesser Caucasus to the southwest of the Kapan Zone, indicating continuous arc magmatic activity along the Eastern Pontides, the Lesser Caucasus and the Sanandaj–Sirjan Zone.

The composite Meghri–Ordubad and Bargushat plutons of the Zangezur–Ordubad region in the southernmost Lesser Caucasus consist of successive Eocene to Pliocene magmatic pulses, and host two stages of porphyry Cu–Mo deposits. New high-precision TIMS U–Pb zircon ages confirm the magmatic sequence recognized by previous Rb–Sr isochron and whole-rock K–Ar dating. A 44.03 ± 0.02 Ma-old granite and a 48.99 ± 0.07 Ma-old granodiorite belong to an initial Eocene magmatic pulse, which is coeval with the first stage of porphyry Cu–Mo formation at Agarak, Hanqasar, Aygedzor and Dastakert. A subsequent Oligocene magmatic pulse was constrained by U–Pb zircon ages at 31.82 ± 0.02 Ma and 33.49 ± 0.02 Ma for a monzonite and a gabbro, and a late Miocene porphyritic granodioritic and granitic pulse yielded ages between 22.46 ± 0.02 Ma and 22.22 ± 0.01 Ma, respectively. The Oligo-Miocene magmatic evolution broadly coincides with the second porphyry-Cu–Mo ore deposit stage, including the major Kadjaran deposit at 26–27 Ma. Primitive mantle-normalized spider diagrams with negative Nb, Ta and Ti anomalies support a subduction-like nature for all Cenozoic magmatic rocks. Eocene magmatic rocks have a normal arc, calc-alkaline to high-K calc-alkaline composition, early Oligocene magmatic rocks a high-K calc-alkaline to shoshonitic composition, and late Oligocene to Mio-Pliocene rocks are adakitic and have a calc-alkaline to high-K calc-alkaline composition. Radiogenic isotopes reveal a mantle-dominated magmatic source, with the mantle component becoming more predominant during the Neogene. Trace element ratio and concentration patterns (Dy/Yb, Sr/Y, La/Yb, Eu/Eu*, Y contents) correlate with the age of the magmatic rocks. They reveal combined amphibole and plagioclase fractionation during the Eocene and the early Oligocene, and amphibole fractionation in the absence of plagioclase during the late Oligocene and the Mio-Pliocene, consistent with Eocene to Pliocene progressive thickening of the crust or increasing pressure of magma differentiation. Characteristic trace element and isotope systematics (Ba vs. Nb/Y, Th/Yb vs. Ba/La, 206 Pb/ 204 Pb vs. Th/Nb, Th/Nb vs. δ 18 O, REE) indicate that Eocene magmatism was dominated by fluid-mobile components, whereas Oligocene and Mio-Pliocene magmatism was dominated by a depleted mantle, compositionally modified by subducted sediments. A two-stage magmatic and metallogenic evolution is proposed for the Zangezur–Ordubad region. Eocene normal arc, calc-alkaline to high-K calc-alkaline magmatism was coeval with extensive Eocene magmatism in Iran attributed to Neotethys subduction. Eocene subduction resulted in the emplacement of small tonnage porphyry Cu–Mo deposits. Subsequent Oligocene and Miocene high-K calc-alkaline and shoshonitic to adakitic magmatism, and the second porphyry Cu–Mo deposit stage coincided with Arabia–Eurasia collision to post-collision tectonics. Magmatism and ore formation are linked to asthenospheric upwelling along translithospheric, transpressional regional faults between the Gondwana-derived South Armenian block and the Eurasian margin, resulting in decompression melting of lithospheric mantle, metasomatised by sediment components added to the mantle during the previous Eocene subduction event.

In the Thrace region of NE Greece, the crystallization and post-solidification cooling below 600 °C of the intrusive suite of the Circum-Rhodope Belt arc-related Evros ophiolite span from 176.4 ± 0.93 to 163.5 ± 3.85 Ma. In the underlying Rhodope high-grade metamorphic basement, (ultra-) high-pressure metamafic rocks are cross-cut by orthogneisses with granitoid protoliths and crystallization ages between 160 ± 0.69 and 154 ± 1.5 Ma. This new U–Pb LA–ICP-MS zircon geochronological data provides evidence that the timing of the evolution of the Evros ophiolite coincides, within analytical error, with granitoid magmatism in the underlying high-grade basement. One of the dated metagranitoid rocks cross-cuts amphibolitized eclogite, indicating that the high-pressure conditions have a maximum age of 160 Ma postdating one of the proposed ages of ultra-high pressure conditions in the Rhodope Massif. The currently earliest recognised Rhodope high/ultra-high pressure metamorphic event is therefore related to the subduction setting which formed the Evros ophiolite. Based on these new temporal constraints and the regional tectonic–geochronologic framework, we discuss and update the geodynamic context connected to the Jurassic subduction–collisional setting at the Rhodope continental margin of Eurasia.

We report here the first inventory of mercury (Hg) contamination in the region of Kedougou, Senegal, where mercury (Hg) is used for gold amalgamation in artisanal small-scale gold mining (ASGM) activities. Sediment cores were sampled during the dry and wet seasons, and at different locations along the Gambia River in the Kedougou region to evaluate the spatio-temporal trends of Hg distribution related to ASGM activities. The sediment samples were analysed for total mercury and trace element concentrations (Cr, Cu, Zn, Pb, As, and Sc). The results highlight high concentrations of total Hg (reaching up to 9.9 mg kg− 1) in sediment cores sampled in the vicinity of ASGM operations, with the highest values reported for the dry season. The calculation of the Hg Enrichment Factor (EF) using Sc as refractory element confirms high enrichments around active sites of gold mining being proportional to the density of miners and the duration of mining activities. The Hg spatial distribution reveals a very local contamination and a limited downstream dispersion of the contaminant. The high Hg concentrations obtained at ASGM sites largely exceed the Sediment Quality Guidelines (SQGs) and the Probable effect concentration (PEC) for the Protection of Aquatic Life recommendation. Our results demonstrate that the ASGM activities discharged large amounts of Hg into the Gambia River ecosystem and that the accumulation of Hg in sediments may represent a significant human health risk and a potential source of toxicity for aquatic organisms.

We quantify the timing of the Tertiary crustal extension in the eastern Rhodope Massif of south Bulgaria using 40Аr/39Аr geochronology to constrain the temporal evolution of exhumation of the metamorphic domes. 40Аr/39Аr analyses of mineral phases with different closure temperatures extracted from metamorphic rocks collected in the footwall and the hanging wall of the extensional system reveal the low-temperature cooling history towards shallow crustal levels. The results reveal that subsequent to regional amphibolite facies metamorphism (i) the hanging wall gradually cooled between 500 and 300 °C during the Paleocene to Late Eocene (64–34 Ma), starting at a low rate of 25 °C/Ma and increasing to 50–67 °C/Ma during 38–34 Ma, (ii) cooling below 400–300 °C of the footwall beneath the extensional detachments occurred in the Middle–Late Eocene (39–35.5 Ma) at an average rate of 35 °C/Ma. 40Аr/39Аr data from the metamorphic basement has been combined with 40Аr/39Аr data from the volcanic and hydrothermal rocks in the vicinity to the extensional domes, to determine the temporal relationships between extensional tectonics, ore-forming and magmatic processes in the region. Extension of the high-grade basement, the ore-formation and volcanism overlaps within a 5 Ma lasting time interval, especially during the cooling and exhumation of the footwall. The eastern Rhodope Massif records an early stage of Eocene extension within the Aegean extensional province, where distinct crustal-scale processes occurred simultaneously implying the presence of cause and effect processes, and thus represents a key example of coeval continental extension, magmatism and hydrothermal activity in the late-stage evolution of the orogens.

The Economic Geology of Iran: Mineral Deposits and Natural Resources . Mansour Ghorbani. Pp. 569. Springer. 2013. ISBN 978-94-007-5624-3. Hardcover or softcover $209US, eBook $159US. This book was written by Mansour Ghorbani with the aim of providing an encyclopedia of Iran’s natural resources, including mineral, energy, and water. The publication covers a large diversity of themes and is subdivided into nine chapters. They are followed by a bibliography subdivided into a section called “References” and a second one termed “Knowledge Sources,” but no explanation is given for this subdivision. As the preface states, this book represents the compilation of 25 years of studies and research, by the author, on mineral and natural resources across Iran. The first chapter, “Nature of Iran and Its Climate,” covers 44 pages and provides a summary of the physiographic divisions, vegetation cover, weather, bird and mammal types, the main mountain ranges, deserts, seas, lakes, and rivers of Iran. This chapter is completed by a set of photos presenting panoramic views of young faults, a mud volcano, islands, ruins, and other attractions. In chapter 2, 20 pages in length, the author summarizes the main geological aspects of Iran, illustrated with five figures representing structural and …

The Coka Marin polymetallic (Cu-Au-Ag-Zn-Pb) deposit belongs to the world-class Bor ore district in Serbia and consists of three lens-shaped orebodies hosted by Late Cretaceous andesitic volcanic rocks. Pyrite is the dominant mineral in the deposit and shows a great variety of textures and zoning. It occurs as fine- to coarse-grained crystals and massive, spongy, colloform, framboidal, oolitic, and replacement aggregates. Complex relationships with other minerals and the presence of microscale mineral inclusions and micro- to nanoscale porosity are common features of the pyrite at Coka Marin. Minor amounts of Cu (up to 7.9 wt.%), Pb (up to 7 wt.%), As (up to 4 wt.%), Ag (up to 1 wt.%), Te (up to 0.07 wt.%), and rarely Sb (up to 0.11 wt.%) were detected in pyrite using an electron microprobe. Zoning and heterogeneity in pyrite is mainly caused by variable copper content. Structurally bound Cu in pyrite from this deposit reported in a previous study was confirmed by our new electron microprobe analyses. Distinct Pb-bearing zones frequently occur in pyrite following oscillatory zoning and crystal shapes. These zones also contain lesser amounts of the other elements mentioned above. Using the focused ion beam (FIB) technique to prepare electron-transparent foils and transmission electron microscopy (TEM), we found that these elements form nanoscale Pb-(±As, Ag, Cu)-bearing inclusions (mosty

Mineralium Deposita, 44 (6), ISSN:0026-4598, ISSN:1432-1866

The Rocabruna and Coll de Pal barite deposits, located in the eastern Pyrenees of Spain, fill karstic cavities within carbonate rocks of Cambrian and Devonian age, respectively. The deposits contain barite, chalcopyrite, tetrahedrite, pyrite and minor sphalerite and galena with saddle dolomite and quartz as gangue. Fluid inclusion data from Coll de Pal quartz and dolomite indicate that the mineralizing fluid was a polysaline CaCl2-rich brine, with temperatures between 125 and 150 °C. C and O isotopic compositions of carbonates in both deposits are consistent with a progressive increase in temperature during deposition. The 34S values of barite, which range from 14.2 to 15.9‰ in Coll de Pal, and from 13.9 to 19.3‰ in Rocabruna, together with 87Sr/86Sr ratios ranging from 0.7118 to 0.7168 in Rocabruna, and from 0.7115 to 0.7136 in Coll de Pal, indicate two different fluid sources. We propose that these deposits formed as a result of mixing between a Ba-rich, sulfate-poor hot fluid, and sulfate-rich solutions of surficial origin. The different Sr isotope ratios in the deposits indicate that the hot Ba-rich fluids involved in each deposit were equilibrated with different rock types (carbonates and shales), in agreement with the geology of the two areas.

Extremely Re-rich molybdenite occurs with pyrite in sodic–calcic, sodic–sericitic and sericitic-altered porphyritic stocks of granodioritic–tonalitic and granitic composition in the Sapes–Kirki–Esymi, Melitena and Maronia areas, northeastern Greece. Molybdenite in the Pagoni Rachi and Sapes deposits is spatially associated with rheniite, as well as with intermediate (Mo,Re)S2 and (Re,Mo)S2 phases, with up to 46 wt % Re. Nanodomains and/or microinclusions of rheniite may produce the observed Re enrichment in the intermediate molybdenite–rheniite phases. The extreme Re content in molybdenite and the unique presence of rheniite in porphyry-type mineralization, combined with preliminary geochemical data (Cu/Mo ratio, Au grades) may indicate that these deposits have affinities with Cu–Au deposits, and should be considered potential targets for gold mineralization in the porphyry environment. In the post-subduction tectonic regime of northern Greece, the extreme Re and Te enrichments in the magmatic-hydrothermal systems over a large areal extent are attributed to an anomalous source (e.g., chemical inhomogenities in the mantle-wedge triggered magmatism), although local scale processes cannot be underestimated.