Metamoprhism of hydrotermally altered rocks in the volcanogenic massive sulfide deposits: the Palmeirópolis, Brazil, example

Introduction Iran hosts numerous types of Volcanogenic massive sulfide (VMS) deposits that occur within different tectonic assemblages and have formed at discrete time periods (Mousivand et al. 2008). The Sabzevar zone hosts several VMS deposits including the Nudeh Cu-Ag deposit (Maghfouri, 2012) and some deposits in the Kharturan area (Tashi et al., 2014), and the Kharturan area locates in the Sabzevar subzone of the Central East Iranian Microcontinent. The Sabzevar subzone mainly involves Mesozoic and Cenozoic rock unites. The Late Cretaceous ophiolite mellanges and volcano-sedimentary sequences have high extension in the Subzone. Based on Rossetti (Rossetti et al. 2010), the Cretaceous rock units were formed in a back-arc setting due to subduction of the Neo-Tethyan oceanic crust beneath the Iranian plate. The exposed rock units of the Kharturan area from bottom to top are dominated by Early Cretaceous, orbitolina-bearing massive limestone, dacitic-andesitic volcanics and related volcaniclastic rocks٫ chert and radiolarite and Late Cretaceous globotrunkana- bearing limestone, paleocene polygenic conglomerate consisting of the Cretaceous volcanics and limestone pebbles (equal to the Kerman conglomerate), and Pliocene weakly-cemented polygenic conglomerate horizon. The Garmabe Paein copper-silver deposit and the Asbkeshan deposit and a few occurrences, are located at 290 km southeast of Shahrood and they have occurred within the Upper Cretaceous volcano-sedimentary sequence in the Sabzevar subzone. The aim of this study is to discuss the genesis of the Garmabe Paein deposit based on geological, textural and structural, mineralogical and geochemical evidence. Materials and methods A field study and sampling was performed during the year 2013. During the field observations, 94 rock samples were collected from the study area, and 45 thin sections were prepared and studied using a polarizing microscope. Also, 5 samples for the XRD method, 21 samples for the XRF and ICP-OES methods were analyzed in the Iranian Mines and Mining Industries Development and Renovation (IMIDRO) Company labs. Results The Garmabe Paein copper-silver deposit is located in the Sabzevar subzone of the Late Cretaceous Volcanio-sedimentary sequence. This mineralization occurred as stratiform and stratabound in a specific stratigraphic horizon. The host rocks of mineralization are andesitic-dacitic volcanic rocks and their related volcaniclastics. The mineralization occurred as four ore facies, from footwall to hanging wall: vein-veinlet-s (stringer), massive, bedded and exhalites. Ore textures and structures involve massive, semi-massive, laminated, banded, vein-veinlets, replacement and open space fillings. Minerlogically, the deposit contains primary minerals such as pyrite, chalcopyrite and magnetite, and secondary minerals such as native copper, cuprite, covellite, malachite and Fe-Mn oxides. Wallrock alterations are dominated by chloritic and minor siliceous and argillic. The highest grades of gold and silver in the deposit are 1 and 19 grams per ton, respectively. The amounts of Zn, Pb, Au, As, Ag and Mn increase from the stringer to the upper part of the deposit. It seems that the occurrence of submarine volcanic activity in the Late Cretaceous back- arc basin have resulted in the deposition of this Besshi type massive sulfide deposit. Discussion Most of characteristics of the Garmabe Paein Cu-Ag deposit including tectonic setting, geological environment, host rocks, geometry, textural and structural, mineralogical and geochemical features, are very similar to those of the Besshi- or pelitic mafic-type (Franklin et al., 2005) volcanogenic massive sulfide (VMS) deposits. Acknowledgements The authors are grateful to the University of Shahrood Grant Commission for research funding and the IMIDRO Company. References Franklin, J.M., Gibson, H.L., Galley, A.G. and Jonasson, I.R., 2005. Volcanogenic massive sulfide deposits. In: J.W. Hedenquist, J.F.H. Thompson, R.J. Goldfarb and J.P. Richads (Editors), Economic Geology 100th Anniversary Volume. Society of Economic Geologists, Littleton, Colorado, pp.523-560. Maghfouri, S., 2012. Geology, mineralogy, geochemistry and genesis of Cu mineralization Within Late Cretaceous Volcano- sedimentary sequence in southwest of Sabzevar, with emphasis on the Nudeh deposit. M.Sc. Thesis, Tarbit Modares University, Tehran, Iran, 312 pp. (In Persian with English abstract) Mousivand, F., Rastad, E. and Peter, J.M., 2008. An overview of volcanogenic massive sulfide deposits of Iran. 33rd International Geology Congress Oslo, Oslo, Norway. Rossetti, F., Nasrabady, M., Vignaroli, G., Theye, T., Gerdes, A., Razavi, M. and MoinVaziri, H., 2010. Early Cretaceous migmatitic mafic granulites from the Sabzevar range (NE Iran): implications for the closure of the Mesozoic peri- Tethyan oceans in central Iran. Journal of Terra Nova, 22(1): 26-34. Tashi, M., Mousivand, F. and Ghasemi, H., 2014. Volcanogenic massive sulfide Cu-Ag mineralization in the Kharturan area, southeast of Shahrood. 1th International Workshop on Tethyan Orogenesis and Metallogeny in Asia and Silk Road Higher Education Cooperation Forum, China University of Geosciences (Wuhan), Wuhan, China.

Mesozoic volcanogenic massive sulfide (VMS) deposits in Mexico

Volcanogenic massive sulphide (VMS) deposits are important global sources of base and precious metals. Igneous geochemistry (petrochemistry) of mafic and felsic rocks associated with VMS deposits is extremely useful in delineating potentially fertile ground for VMS mineralization. In mafic-dominated, juvenile environments (e.g. mafic, bimodal mafic and mafic-siliciclastic VMS-types) VMS deposits are associated with boninite and low-Ti island arc tholeiite, mid-ocean ridge basalt, and back-arc basin basalt. These rocks are ultimately sourced from either depleted arc mantle wedge (e.g. boninite, low Ti island arc tholeiite) or upwelling depleted, mid-ocean ridge or back-arc asthenospheric mantle (e.g. MORB and back-arc basin basalt). In evolved environments, those associated with continental crust and typically dominated by felsic magmatism (e.g. bimodal felsic and felsic-siliciclastic VMS-types), VMS-associated mafic rocks have alkalic (ocean island basalt-like) and/or mid-ocean ridge/back-arc basin basalt-like signatures. In these environments alkalic basalt and mid-ocean ridge/back-arc basin basalt-like mafic rocks overlie felsic rocks and mineralization and represent melts derived from lithospheric and asthenospheric mantle sources, respectively. Felsic rocks in Archean sequences are typically tholeiitic, have elevated high field strength elements (HFSE) and rare earth elements (REE), and FIII affinities (low Zr/Y and La/Yb n , flat chondrite-normalized rare earth element profiles). In post-Archean evolved environments, felsic rocks associated with VMS deposits have HFSE- and REE-enrichment and within-plate signatures on discrimination diagrams, like their Archean counterparts, but are more calc–alkalic in composition and commonly have FII affinities. Felsic rocks associated with VMS deposits in post-Archean mafic-dominated, juvenile substrates are associated with trace element depleted rhyolites with tholeiitic to boninite-like signatures and M-type and FIV affinities on discrimination plots. Using mafic or felsic rocks in isolation may lead to erroneous assignments of prospectivity for terrains; however, when mafic and felsic rocks are used in tandem with geological context they are powerful tools in outlining potentially prospective regions. Within VMS-hosting environments there are specific petrochemical assemblages of mafic and felsic rocks. Petrochemical assemblages are specific lithogeochemical associations between mafic and felsic rocks that are common to VMS forming environments and are useful in identifying two key ingredients required to form prospective VMS belts: (1) rifting; and (2) high temperature magmatism.

The production of Cu-Zn from volcanogenic massive sulfide (VMS) deposits in the eastern Pontides began in the early 1900s, with the exploitation of high-grade ores scattered across the district. The district still possesses economically important blind VMS and associated sulfide deposits. Careful descriptive documentation of the typical features of these VMS ores illustrated the geological characteristics that are important in identifying ore localities and can be used to define exploration targets. The eastern Pontide VMS deposits are examples of volcanic-hosted massive sulfide deposits that exhibit many of the characteristics typical of bimodal-felsic- type VMS mineralization. Nearly all known VMS deposits in the region are hosted by the Kızılkaya Formation, which is characterized by Late Cretaceous dacitic/rhyolitic volcanic rocks that are typically located at the top contact of the dacitic/rhyolitic pile or within the lower part of the overlying polymodal sequence containing various proportions of volcanic and sedimentary facies. Most VMS deposits are composed of a mound of high-grade massive sulfides formed above a zone of lower-grade stringer veins and disseminated mineralization. The dominant sulfide minerals in most deposits are pyrite, chalcopyrite, and sphalerite. Au also occurs in some deposits. The hydrothermal ore facies are diagnostic of subaqueous emplacement of the Pontide massive sulfide deposits that were deposited on the Cretaceous ocean floor. The immediate host lithologies associated with VMS mineralization have typically experienced intense and widespread alteration. The trace element geochemical signatures of the host rocks indicated that the Pontide VMS deposits likely formed in an extensional tectonic regime during subduction. Major lineaments and circular structures exerted fundamental controls on the locations of the VMS deposits in the eastern Pontide district. Age determinations indicated that almost all of the deposits in this region formed in a restricted time interval between ca. 91.1 and 82 Ma. The sulfur isotope compositions of the ore-forming fluids were consistent with those of fluids derived from modified seawater.

Partial least squares-discriminant analysis of trace element compositions of magnetite from various VMS deposit subtypes: Application to mineral exploration

Chapter 5 Characterisation of Archean Subaqueous Calderas in Canada: Physical Volcanology, Carbonate-Rich Hydrothermal Alteration and a New Exploration Model

We report whole-rock major, trace, and platinum-group element (PGE) geochemistry of volcanic rocks from the Teutonic Bore complex that hosts the Jaguar and Bentley Cu–Zn volcanogenic massive sulfide (VMS) deposits. This study aims to understand their sulfide saturation history and chalcophile element evolution during differentiation of the Jaguar and Bentley magmas, and investigate the role of chalcophile element fertility on the formation of VMS deposits. The fractionated primitive mantle–normalized trace element patterns, with negative Nb and Ti anomalies of basalts, andesites, dacites, and rhyolites from Jaguar and Bentley, are similar to each other. The trace elements and PGE show continuous variations when plotted against fractionation indices such as Yb, which can be explained by a two-stage fractional crystallization model: stage 1 Rayleigh fractionation of plagioclase + clinopyroxene + Cr-spinel, and stage 2 the fractional of plagioclase + clinopyroxene + magnetite + 0.1 wt% sulfide liquid. Dolerites, which postdate the mineralization, differ from the other rock types and require a different magma source. Andesite and basalt are the most PGE-enriched lithologies in Jaguar and Bentley. The PGE behave incompatibly in the early stage of magma differentiation at < 4 ppm Yb, whereas they abruptly decrease at > 4 ppm Yb, indicating sulfide saturation at this point. When Pd/MgO and Pd/Pt are used as chalcophile element fertility indicators, the andesite before sulfide saturation (< 4 ppm Yb) is as fertile as the magmas associated with porphyry Cu-only deposits. In contrast, the andesite after sulfide saturation and other lithologies are characterized by markedly depleted fertility similar to those of barren suites. This suggests that sulfide-undersaturated andesite, and probably basalt, may have been a significant source for Cu in the Jaguar and Bentley Cu–Zn VMS deposits. However, the Au fertility of the Jaguar and Bentley andesite must have been low and not enough to form Au-rich VMS deposits because their Pd/MgO and Pd/Pt values are 5–10 times lower than those of andesite and dacite from the modern Au-rich seafloor massive sulfide deposits. This can be explained if ore formation occurred shortly after sulfide saturation. If the amount of sulfide melt to precipitate was small, Au, with its high partition coefficient into immiscible sulfide melts, would have been largely stripped from the silicate melt, whereas Cu, with its lower partition coefficient, would be little affected. Our study shows that chalcophile element fertility may play an important role in the formation of VMS deposits, especially in controlling the Au contents of the ore, if the magmatic-hydrothermal component is the dominant source for metals in VMS systems.

Volcanogenic massive sulfide (VMS) deposits with advanced argillic alteration display characteristics typical of conventional VMS and high-sulfidation epithermal deposits. Unlike conventional VMS deposits, these “hybrid” VMS are interpreted to have formed through a magmatic fluid contribution to an evolved, seawater-dominated, hydrothermal system. The close spatial association of advanced argillic alteration assemblages with more typical chlorite–sericite assemblages in the same VMS deposit has implications for the controls on magmatic versus seawater convective systems that have not been previously addressed in the literature. The Neoarchean Onaman assemblage (ca. 2780–2769 Ma) in northwestern Ontario hosts a conventional base metal VMS system with chlorite–sericite alteration that is overprinted by argillic and advanced argillic alteration, now manifested as a metamorphosed zone of kyanite–chloritoid–calcite–Fe–chlorite, that is associated with a barren, pyritic VMS deposit. The change from typical to advanced argillic alteration occurred during, or immediately following, the deposition of a tonalite clast-bearing heterolithic breccia, which recorded the uplift and subaerial exposure of the larger volcanic edifice. We postulate that the reactivation of synvolcanic structures during uplift, concomitant localized subsidence, and magmatism enhanced cross-stratal permeability and allowed for a direct magmatic volatile input into, or overprint on, an evolved seawater-dominated hydrothermal system. Our results suggest that geodynamic regimes exert a strong local, and possibly regional, control on the style, timing, and fluid characteristics of VMS hydrothermal systems. The association of advanced argillic alteration with barren pyritic massive sulfide also suggests that magmatic volatile input alone is not sufficient to enrich VMS systems in gold. This interpretation is consistent with observations from other magmatic–hydrothermal systems such as porphyry and epithermal deposits.

A large number of volcanogenic massive sulfide (VMS) deposits are associated with Late Cretaceous to Eocene arc-like volcanic rocks in the eastern Pontides of NE Turkey. Cu isotope studies on thirteen VMS and two vein deposits were undertaken to examine the nature of copper isotope variations and to compare these with other VMS and black smoker deposits. ϕ65Cu of chalcopyrite from these deposits range between +0.34 and -0.62‰. Chalcopyrite from the VMS deposits of the eastern Pontides have a mean ϕ65Cu = −0.13‰. ϕ65Cu of chalcopyrite is generally heavier than that of corresponding bornite. The range of ϕ65Cu for chalcopyrite from VMS deposits in the eastern Pontides is larger than that observed from Alexandrinka, a Devonian VMS deposit in the southern Urals, but is significantly smaller than the up to 3‰ variations observed from individual modern sea-floor hydrothermal fields along modern mid-ocean ridges. The range of Cu isotope variation in VMS deposits from the eastern Pontides is interpreted to result from processes related to both oxidation and leaching of previously deposited copper by seawater and to its subsequent deposition elsewhere in the hydrothermal system.

ABSTRACT: Ground-Penetrating Radar (GPR) simulation plays a pivotal role in geophysical methods, aiding in survey design, understanding physical behaviour, and quantifying responses. This study employs the gprMax software to simulate the propagation of electromagnetic waves through different Volcanogenic Massive Sulfide (VMS) deposits, each with unique electrical properties. The fundamentals of GPR modeling and factors influencing survey design (operating frequency, recording time window, temporal and spatial sampling interval) are outlined. Careful consideration of these parameters is essential for effective GPR surveys. In addition, results from the simulations of EM wave propagation through VMS minerals such as Galena, Bornite, Magnetite, Pyrite, Sphalerite and Hematite, and their host rocks were utilized to calculate wave velocities in each mineral, rendering it possible to determine the location of Boundaries of VMS veins within the host rock using this method. Some deposits with lower electrical conductivities, showed possibility of being imaged successfully using Electromagnetic (EM) methods. In contrast, some other deposits, having higher electrical conductivities, tended to weaken electromagnetic signals, especially within the frequency range used in GPR applications. This study enhances our comprehension of GPR simulation and its possible uses in geophysics, specifically in the characterization of diverse geophysical materials that possess distinct electrical properties. 1 INTRODUCTION Volcanogenic massive sulfide (VMS) deposits, are key sources of metals like Zn, Cu, Pb, Ag, and Au. Also, there is a substantial proportion of pyrite, or iron sulphide (FeS2) that is frequently connected to VMS occurrences. The economic importance of these deposits is underscored by their contribution to metal production. Most VMS deposits consist of massive (&amp;gt;40 percent) sulphide (typically pyrite, pyrrhotite, chalcopyrite, sphalerite, and galena as well as magnetite) (Best, 2015). These minerals and their associated economic minerals are listed in Table 1. GPR simulation is a powerful tool in delineating VMS deposits, crucial for optimizing GPR survey parameters and understanding mineral-host rock interactions. This approach facilitates accurate mapping and exploration of VMS deposits, enhancing the effectiveness of geophysical surveys by allowing for precise adjustments in survey design based on the simulation outcomes.

Metallogeny of volcanogenic massive sulfide deposits of Iran

Hydrothermal mobilisation of Au and other metals in supra-subduction oceanic crust: Insights from the Troodos ophiolite

Ancient volcanogenic massive sulfide (VMS) deposits formed in rifted arc, back-arc, and other extensional geodynamic environments and were deformed during later convergent collisional and/or accretionary events. Primary features of deposits influenced the development of tectonic structures. Except for pyrite, common sulfides in VMS deposits are much weaker than their volcanic host rocks. During deformation, strain is taken by the weak sericitic and chloritic alteration envelope surrounding the deposits and by the sulfide bodies themselves, which act as shear zones, undergo hinge thickening and limb attenuation during regional folding, and are deformed into elongate bodies parallel to regional fold hinges and stretching lineations. A tectonic foliation forms as a sulfide banding in the interior of VMS lenses due to shearing and flattening of primary textural and compositional heterogeneities and as a banded silicate-sulfide tectonic foliation along the margins of the VMS lenses due to transposition and shearing of primary silicate (exhalites)-sulfide layers. Other characteristic structures, such as cusps, piercement cusps, piercement veins, and durchbewegung structures (sulfide breccias), formed as a result of the strong competency contrast between the massive sulfide deposits and their host volcanic rocks. Some features of VMS deposits may have both primary and tectonic components, requiring careful mapping of volcanic lithofacies and primary and tectonic structures to assess the nature of these features. One example is the vertical stacking of VMS lenses. The stacking may be primary, due to the rapid burial of lenses by volcanic or sedimentary deposits as the upward flow of hydrothermal fluids continued and precipitated new lenses above the earlier formed lenses. Or it may be tectonic, due to thrusting or isoclinal folding and transposition of the VMS lenses. Metal zoning (Cu/Cu + Zn), produced by zone refining at the seafloor or subseafloor, is refractory to deformation and metamorphism and can be used to delineate hydrothermal fluid upflow zones and, together with stratigraphic mapping, determine if the stacking is primary, tectonic, or both. Similarly, the elongation of VMS lenses may have a primary component due to the deposition and coalescence of sulfide lenses along linear synvolcanic faults or fissures, as well as a tectonic component due to mechanical remobilization of sulfides parallel to linear structural features in the host volcanic rocks. Structural mapping of VMS deposits is hampered by low-temperature recrystallization of sulfides, which masks the effects of deformation, by discontinuous and abrupt lithofacies changes in the volcanic host rocks, and by the weak development of tectonic fabrics and strong strain partitioning in volcanic rocks. To mitigate these issues, mapping of volcanic lithofacies should be done concurrently with structural mapping to delineate repeated stratigraphic panels across reactivated faults and to identify, in the absence of well-developed fabrics, regional folds characterized by abrupt changes in strata orientation from limbs to hinge. Where well-layered sedimentary rocks are intercalated with volcanic rocks, structures should be mapped in the sedimentary rocks and then correlated with those in volcanic rocks to alleviate difficulties in mapping structures in volcanic rocks and defining the sequence of deformation events that affected the volcanic rocks and their VMS deposits.

The Paleoproterozoic Flin Flon mining district is one of the world’s most prolific volcanogenic massive sulfide (VMS) camps and includes a single stratigraphic interval that hosts the 85.5 million tonne (Mt) Flin Flon, 777, and Callinan Zn-Cu-(Au) deposits. Rapid seafloor burial of the VMS hydrothermal system by a thick succession of pillowed basalt resulted in the hanging-wall strata being affected to varying degrees by the still upward migrating fluids. This hanging-wall alteration hydrothermal fingerprint allows delineation of the regionally metamorphosed paleohydrothermal system, and its characterization has the potential to lead to discovery of buried, stacked, or structurally displaced mineralization. Evidence for the presence of continued seafloor hydrothermal activity above the Flin Flon-Callinan VMS horizon is observed in the pillowed flows, interlayered hyaloclastite-rich flow tops, and also within finely bedded interflow volcaniclastic sediment. A 30% to 60% metalliferous exhalative component was detected through geochemical and mineral analysis in interpillow volcaniclastic rocks, chert, and epidosite in the hanging-wall sequence. The regional distribution of Fe- and Mg-rich chlorite, epidote-clinozoisite, biotite-annite, actinolite-hornblende-ferrotschermakite, and stilpnomelane and albite-oligoclase modifies metamorphic isograds and defines discrete vertical fluid pathways controlled by synvolcanic growth faults and associated sill-dike swarms. Silica-enriched hanging-wall alteration zones are proximal to Fe-Ti basalt sills and occur as discrete hanging-wall zones parallel to the plunge of the 62 Mt Flin Flon deposit. Anomalous concentrations of Hg, Sb, Ag, Pb, Te, As, Au, and Bi form within these hanging-wall halo alteration zones, indicating migration of the more volatile metals present in the underlying VMS deposits. Synvolcanic depressions, dike swarms, and hydrothermal-metamorphic fluid corridors are detectable through trace element anomalies, trace mineral chemistry, and 18O isotope geochemistry. Oxygen isotope analysis of the Flin Flon-777-Callinan VMS hanging-wall strata defines a number of high δ O18 anomalies extending 1,200 m above that indicate that <300°C subseafloor hydrothermal activity continued after burial of the massive sulfide deposits. Coupled with the geochemical and mineral chemical anomalies, this is indicative of the presence of continued, relatively low temperature hydrothermal fluid “leakage” from a robust seafloor hydrothermal event that generated the VMS deposits. A combination of techniques, including mineral chemistry, isotope, and trace element data, is demonstrated to be successful in identifying and delineating zones of hanging-wall hydrothermal alteration in greenschist- to amphibolite-grade metamorphic rocks of the Flin Flon mining camp. Use of these, coupled with mapping to define periods of quiescence as marked by horizons of sedimentary rocks in the hanging-wall basalts of the Hidden Formation, has the potential to lead to discovery of deeply buried deposits on the Flin Flon horizon or deposits at higher stratigraphic levels. Our findings indicate that the basaltic hanging wall on the Flin Flon-777-Callinan hydrothermal system was an efficient cap on the system, with vestiges of continued hydrothermal fluid flow detected in the interpillow and interflow components. These volumetrically minor components are critical sampling media and are pertinent to global exploration for detection of VMS mineralization buried beneath thick mafic volcanic sequences.

The Skellefte district in northern Sweden hosts many volcanogenic massive sulfide (VMS) deposits and is considered one of the most important European mining districts for Cu, Zn, Pb, Ag, and Au. The volcanic and sedimentary rocks that the VMS deposits are hosted in were deformed during the Svecokarelian orogeny, with three documented regional deformation phases. These events imparted a distinct attitude and geometry to the deposits, their host succession, and discordant zones of synvolcanic hydrothermal alteration. Few studies have investigated the detailed deformation effects on the sulfide minerals. In this contribution, we document the structural characteristics and remobilization history of mineralization at the Rävliden North Zn-Pb-Cu-Ag deposit—one of the most important recent discoveries in the district consisting of 8.5 million tonnes (Mt) grading 1.01% Cu, 3.45% Zn, 0.53% Pb, 78.60 g/t Ag, and 0.23 g/t Au. At Rävliden, massive to semimassive sphalerite-rich mineralization with lesser pyrrhotite, galena, pyrite, and silver minerals occurs structurally above stringer-type mineralization dominated by chalcopyrite, pyrrhotite, and pyrite. These mineralization types exhibit evidence of deformation and remobilization such as (1) sulfide-alignment parallel to tectonic foliations; (2) rounded wall-rock tectonoclasts in a ductile deformed sulfide matrix (“ball ore” or durchbewegt ore); and (3) sulfides in tension gashes, strain shadows, piercement veins, and late, straight veinlets crosscutting tectonic fabrics. These features are attributed to polyphase deformation during the D1, D2, and D3 events at temperature ranging from 200° to 550°C. Remobilization of sulfides was mostly within the bounds of the main mineralization (i.e., 10–100 m), with few local external occurrences. A combination of solid-state and fluid-assisted remobilization processes are inferred. Rare brittle veinlets and zeolite-cemented breccias with sphalerite, galena, and silver minerals occur in the stratigraphic hanging wall, where they crosscut all Svecokarelian structures. This mineralization type is highly reminiscent of Phanerozoic low-T vein- and breccia-hosted Pb-Zn deposits of the Lycksele-Storuman area west of Rävliden North, which have been linked to far-field effects associated with the opening of the Iapetus Ocean (0.7–0.5 Ga). We suggest that this Zn-Pb mineralizing event led to the formation of the late sulfide-zeolite veinlets and breccias at Rävliden North, and that elements such as Ag and Sb within this mineralization were locally remobilized from Rävliden.