The bedrock in northernmost Sweden comprises Archaean (2.8–2.65 Ga) and Karelian (2.4–1.96 Ga) rocks and a volumetrically dominant population of magmatic rocks which formed during the Svecofennian (1.9–1.8 Ga) stage. New Ar–Ar (hornblende and muscovite) and U–Pb (zircon and monazite) isotopic results from representative lithologies are used to shed further light on the geological evolution. With respect to the Ar–Ar isotopic system, somewhat variable dates (hornblende) are interpreted as cooling ages that indicate different uplift histories, following a 1.8 Ga metamorphic peak, at different sides of the Karesuando-Arjeplog deformation zone. Other post-1.7 Ga 40Ar/39Ar ages are suggested to reflect either a neocrystallisation (muscovite) or an event leading to isotopic resetting (hornblende). It is suggested that post-1.76 Ga crustal processes have influenced the Ar–Ar mineral systems during three relatively short-lived (a few tens of million years) stages; peaking at 1.73 Ga, 1.63 Ga and 1.55 Ga. Tentatively, the timing of these stages is coupled with far-field effects that elsewhere are associated with the alkali-rich granitic magmatism forming part of the Transscandinavian Igneous Belt (the 1.73 Ga event) and Rapakivi massifs (the 1.63 and 1.56 Ga events). It is proposed that the N-S to NW–SE orientation of these vast, regional granitic complexes matches that of major deformation zones in northernmost Fennoscandia and that locally initiated hydrothermal fluids followed weakness zones in the crust and ultimately led to element mobilisation, new mineral growth and isotopic over-printing preferentially affecting shear- and ore zones.

The highly fractured Jurassic carbonates at Jbel Tirremi in northeastern Morocco host fluorite-baryte deposit. The mineralization occurs both as stratabound in marl-limestone contact and as fault (NS and NNW-SSE)-hosted veins. The mineral paragenesis consists of two fluorite and baryte generations and calcite with subordinate amounts of quartz, dolomite, traces of sulfides (chalcopyrite, pyrite, galena), and oxidized minerals. Fluid inclusion data reveal that hot moderately saline fluids derived from the Paleozoic basement mixed with Triassic brines and cooler, meteoric waters. The REY inventory, C-O-S-Pb-Sr-Nd isotope, and crush-leach data point to the Paleozoic basement as the primary source of metals with a contribution from the Triassic red beds. The refined ore genetic model developed in this study from our new geological and geochemical data includes the downward movement of Triassic-Jurassic evaporated seawaters along normal faults, followed by the leaching of metals from Paleozoic and Triassic rocks, and the subsequent upward flow of these metalliferous fluids. During the Late Cretaceous-Paleocene basin inversion, the deep-seated ore-forming fluids migrated upward, which eventually mixed with Triassic brines and cooler meteoric waters. This fluid mixing caused the precipitation of multiple generations of fluorite and baryte.

This study focuses on the origin of fluorite ore deposits that are associated with the Eocene alkaline igneous suite of the Tamazert complex in the Moroccan High Atlas. Based on field observations and mineralogy, two major ore styles were identified: 1) a disseminated purple fluorite in aegirine-rich nepheline syenites (stage 1) and 2) a banded purple-white fluorite ore in karstic cavities and veins hosted in the Jurassic carbonate (stage 2). Both fluorite mineralization stages are commonly accompanied by calcite. The distribution of fluorite deposits at the peripheries of syenite and the surrounding Jurassic carbonates suggests the development of long-lived hydrologic systems around the shallow intrusion. Based on fluid inclusion, Rare Earth Elements and Yttrium (REY), and C-O isotopic constraints, this study reveals that different fluid systems were responsible for the deposition of fluorite ores in and around the Tamazert alkaline igneous complex. The disseminated interstitial fluorite precipitated from a F-rich magmatic-hydrothermal fluid, which exsolved from the highly evolved alkaline-silicate melt and was subsequently altered by Na-Ca metasomatic brines. Vein-type fluorite deposits hosted in the Jurassic car-bonates precipitated from low salinity (1.6-8.5 wt% NaCl equiv.) and heated (T-h = 118-157 degrees C) meteoric fluids, which migrated in response to the heat flow around the shallow intrusion. Fluid cooling, fluid interaction with Jurassic carbonates, and pressure fluctuations were the most important fluorite deposition mechanisms. The evolved melt provided F and REY for the interstitial fluorites, whereas meteoric fluids leached F- from syenites and other F-bearing igneous rocks. Based on the fractionation pattern, the REY inventory of the vein fluorites was acquired by interaction of meteoric fluids with Jurassic carbonates.

Defining the variability and distribution ofmethane seeps and microbial activity in the aftermath of theMarinoan glaciation is a long-standing challenge in the field of Snowballmodels. Early diagenetic barite is commonly linked to tepee structures and associated breccias lacking microbial textures and fabrics, giving the impression that chemosynthetic microbes, or at least methane-tolerant microbes, did not participate in the carbonate production of their cap carbonate host. This apparent paradox has been an outstanding question in the lowermost Ediacaran cap carbonates of the Taoudeni Basin, NW Africa. In the Kaarta Mountains of Mali these carbonates exhibit, over short distances (<10 km), sharp facies-related environmentalmodifications with quiescent-dominated seafloor conditions, episodically interrupted by metre-scale disrupted substrates. The latter comprises fissure and fracture networks, occluded with tabular- and rosette-shaped barite cements, and sealed by decimetre-scale stromatolitic build-ups exhibiting intergrowths with barite needles. The strongly C-13-depleted carbon isotope values of the microbial carbonates (delta C-13 as low as -43.2 % PDB) suggest the influence of methane, also preserved as fluid inclusions in barite crystals (documentedwith RAMAN spectroscopy) derived froma gas reservoir belowthe cap carbonate. Th of other fluid inclusions (Linkam microthermometry), ranging from174 degrees C to 222 degrees C, provides minimum entrapment temperatures for barite precipitation. The microbially induced oxidation of methane and input of Ba-rich fluids were coupled to reduction of sulphate derived from seawater. The Sr/S isotope ratio and barite shape and size point to diagenetic barite crystals. The biomarkers yielded by the cap carbonate reflect a C-29-dominant steroidal signature characteristic of stigmastanoid algal blooms. Although present-day microbial build-ups related to methane sources commonly occur in deep substrates and under anoxic bottom waters, the cap carbonate of the KaartaMountains is representative of shallower substrates, whereas its biomarkers point to deposition under episodic non-oxidising conditions. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The Solstad copper deposit, located in SE Sweden, is hosted by a quartz-rich rock sliver surrounded by a granite belonging to the 1.8 Ga Transscandinavian Igneous Belt. Ore petrographic studies have revealed a number of previously unrecognized opaque phases, including several Co phases, selenides and tellurides. Based on an in situ U-Pb investigation of zircons from a mineralized sample, it is suggested that zircons have a detrital origin and that the quartz-rich host rock is a xenolith belonging to the c. 1.88-1.86 Ga Vastervik quartzite formation. A low-radiogenic galena sample implies that the source for the metals in the ore has a primitive origin, probably the basaltic lavas (now amphibolites) that are intercalated in the Vastervik quartzite. Fluid inclusion studies in quartz distinguish four distinct ore fluids: (1) a hypersaline halite-bearing aqueous fluid related to an early (1.85-1.86 Ga) chalcopyrite depositional stage, (2) a subsequent CO2-rich fluid, that deposited native gold, tellurides, selenides and bismuthinite, developed (at >= 1.8 Ga) as a result of a phase separation, (3), a moderate- to high-salinity aqueous fluid did also develop at this event and led to the deposition of bornite and (4) a concluding, low-salinity aqueous fluid stage (at <= 1.8 Ga) caused oxidation to covelline and digenite of previously formed phases. It is proposed that the Solstad deposit and other Cu +/- Co-rich sulphide (+/- magnetite) occurrences in the Vastervik region along the southernmost margin of the 1.9-1.8 Ga Svecofennian Domain, represent a distinct ore type associated with quartzites and amphibolites.

The Bou Azzer district in Morocco has a long mining history since the beginning of the XXst century during which it has become the only world producer of Co from primary, hydrothermal Co arsenide ores. Orebodies are structurally controlled, and mainly distributed along fault contacts between Cryogenian ophiolite-related serpentinite bodies and intrusive quartz diorite or, locally, ophiolitic gabbros or Ediacaran volcanic rocks. Ore formation took place through a multi-stage mineralizing process that included an early stage composed by gold, quartz, chlorite, muscovite and calcite, followed by the main arsenide and sulfarsenide stage (subdivided into three substages, IIa: Ni-rich, Co ores, IIb: Co-Fe ores and IIc: Fe-Co ores), and ending with an epithermal stage characterized by the precipitation of sulfides along with quartz and calcite. Field relations and most previous geochronologic dating pointed to a post Pan-African age of ore formation, mainly coincident with the Hercynian orogeny. The isotopic study presented in this paper includes S, Pb, Rb/Sr and Sm/Nd data of a set of ore mineral samples from three deposits (Aghbar, Tamdrost and Ait Ahmane), as well as of regional samples representative of the different lithologies occurring in the Bou Azzer area. The isotope data set was completed with S isotope analyses of arsenide and sulfarsenide minerals from five ore deposits (Filon 7/5, Aghbar, Tamdrost, Ightem and AitAhmane) and of some whole-rock regional samples. Results show that ores formed during multi-episodic hydrothermal events connected with hercynian reactivation of Devonian-Carboniferous faults, supporting previous geochronologic dating. The obtained Pb, Sr, Nd and S isotopic signatures of ore minerals and regional rocks further show that ophiolite-related lithologies became isotopically modified by interaction with crustal material and afterwards acted as the main source of ore-forming elements. Nevertheless, isotopic data do not fully concur with such a simple scenario but are quite consistent with a rather complex interpretation based on multi-source origin of some elements and isotopes scavenged from a number of isotopically different lithologies both from the inferred basement and the volcanic and sedimentary cover.

We present the results of a study of an Eoarchean rock assemblage in the Dniester-Bouh Domain of the Ukrainian Shield. This comprises granulite-facies granitoids intercalated with mafic and ultramafic granulites. Zircon U-Pb geochronology indicates enderbite crystallisation at 3786 +/- 32 Ma, followed by a subsequent event at ca. 3500 Ma. Several events can be tentatively identified that affected these rocks between ca. 3000 and 2700 Ma. The last zircon growth event took place in response to granulite facies metamorphism and included two separate episodes at ca. 2000 and ca. 1900 Ma. The oldest two zircon populations in enderbites have epsilon Hf values around 0, indicating their crystallisation from a protolith with a short crustal residence time. Zircons that crystallised during the 3000-2700 Ma event(s) vary in Hf isotope systematics from epsilon Hf similar to 1 at ca. 3000 Ma to epsilon Hf similar to -14 at c. 2700 Ma. Paleoprotemzoic zircons reveal even more significant variations in EHf value from +6 to -22. Such variations are indicative of juvenile input and mixing with old non-radiogenic Hf. All Eoarchean rocks are depleted in incompatible trace elements and have negative Ta-Nb, P, and Ti anomalies. Compared to the typical TTG associations, enderbites record depletion in felsic components (SiO2, Na2O, K2O, Rb, Th), and enrichment in mafic ones (TiO2, MgO, CaO, V), allowing them to be defined as "mafic" or "depleted" TTG. Geochemical data indicate that mafic and ultramafic rocks of the Dniester-Bouh Domain formed by shallow high-degree melting of the mantle, with the absence of garnet in their source, and the presence of residual Tibearing minerals and/or amphibole. In contrast, enderbites were formed from a mixed garnet-bearing amphibolite - eclogite source, i.e. melting over a range of pressures/depths. Our preferred model for the formation of the Eoarchean rock association involves the shallow melting of mantle and formation of basalts and accompanying ultramafic cumulates at a spreading centre, with subsequent underthrusting of one segment of oceanic crust beneath the other, and partial melting of hydrated metamorphosed (eclogitized) mafic rocks in the underthrust plate, leading to the formation of the TTG melts.

Gotland is an island in the central part of the Baltic Sea, with up to 800 m Palaeozoic sedimentary rocks on top of a Precambrian basement belonging to the East European Craton. In this contribution, two major ductile deformation zones (Lickershamn - Ostergarn and Lilla Karlso-Ronehamn) are recognized and connected with the Vingaker-Nykoping and Linkoping-Loftahammar Deformation Zones in the adjacent Fennoscandian Shield. These deformation zones constitute the borders between three main Precambrian segments that are correlated with crustal units within the Fennoscandian Shield and concealed parts of the East European Craton east of the Baltic Sea. The Faro-Northern Gotland segment is dominated by continental Jotnian sandstones and Svecofennian metasedimentary rocks, separated from each other by a fault and an associated dolerite dyke. The metasediments show a specific provenance pattern with 3.29 Ga, 2.95-2.63 Ga and 2.11-1.96 Ga sources, devoid of < 1.90 Ga detrital zircons. The Alby granite truncates the metasedimentary rocks of the Faro-Northern Gotland segment and is part of the 1.58 Ga Riga rapakivi batholith. The Central Gotland segment is dominated by metabasalts and 1.90-1.88 Ga granitoids and is correlated with the Tiveden and Valdemarsvik areas in the Fennoscandian Shield. The amphibolites in the Southern Gotland segment are correlated with 1.87-1.86 Ga metabasalts, intercalated with the Vastervik quartzites in the Fennoscandian Shield. They were intruded by TIB 0 granitoids, recognized at Frigsarve and correlated with the Askersund-Loftahammar granitoids in the Fennoscandian Shield. The TIB 0 granitoids on Gotland can also be followed to the east, first to the E6-1 offshore drill hole, 30 km west of the Latvian coast and further east into southwestern Latvia and western Lithuania as a major component in the MidLithuanian Domain. The Kvarne granitoid on southernmost Gotland is correlated with the TIB 1a generation in the Fennoscandian Shield and with granitoids within the Mid-Lithuanian Domain. 1.48 Ga small stitching plutons on southern Gotland penetrate the TIB 0 and 1a granitoids and are correlated with the Gotemar and Karlshamn plutons in the Fennoscandian Shield and several plutons in western and southern Lithuania.

Concentrations of a large set of major and trace elements, and Sr, Nd and Pb isotope ratios were measured in Holocene sediments cored in the western deep Black Sea in order to unravel: (1) the controls of element enrichment, and (2) sources of the detrital component. The transition of the basin from oxic to euxinic resulted in enrichment or depletion in a number of elements in the deep-sea sediments. Authigenic Fe enrichment appears to depend on the amount of Fe mobilized from the sediment through the benthic redox shuttle mechanism and amount of Fe mobilized from the sediment through the benthic redox shuttle mechanism and free H2S in the water column (degree of "euxinization"). Manganese enrichment is controlled by diagenetic reactions within the sediment: the dissolution of Mn minerals, Mn2+ diffusion upward and reprecipitation. Barium enrichment is also controlled by diagenetic reactions, sulfate reduction and methanogenesis, that take place above and below the sulfate-methane transition, respectively. The major part of V, Co, Ni, Cu, Zn, Cr, Mo, Cd and Sb is inferred to have co-precipitated with Fe in the euxinic deep waters and to have been incorporated into authigenic Fe-sulfides. Basin reservoir effect additionally influences the Mo enrichment. The U enrichment is interpreted to have a different origin in the two organic-rich stratigraphic units (II and I). It is inferred to be: (i) at the expense of the U inventory of the deepwater pool and a result of inorganic reduction of U at euxinic conditions in the lower Unit II; and (ii) at the expense of the U inventory of the surface water pool and a result of biogenic uptake and transfer to the sediment by the plankton in the upper Unit I. The high field strength elements are closely linked to the detrital component and their depletion in the organic-rich sediments reflects a dilution of the detrital component by the biogenic one. The enrichments of REE, Sn and Th are likely controlled by adsorption on clay minerals. Sr-Nd-Pb isotope compositions of the alumino-silicate component of the studied sediments are relatively uniform. They are most likely controlled by riverine suspended matter supplied mainly in the NW Black Sea (Danube Delta) and transported southward by marine currents, and to a lesser degree by suspended matter from the small rivers draining SE Bulgaria and NW Turkey. Wind-blown dust from the Sahara Desert appears to have a minor contribution to the alumino-silicate component of the sediments. The slight shift in the Pb isotopes in Unit I upper layers is possibly caused by the addition of anthropogenic Pb. (C) 2020 Institute of Oceanology of the Polish Academy of Sciences. Production and hosting by Elsevier B.V.

Numerous sandstone-hosted Pb-Zn deposits occur along the present-day erosional front of the eastern Scandinavian Caledonides. The largest deposit is Laisvall (64.3 Mt at 4.0% Pb, 0.6% Zn and 9.0 g/t Ag) and since mineralisations generally share similar characteristics (reminding of both SEDEX and MVT-style) the term Laisvall-type has often been used. Typically, mineralised zones occur along sedimentary bedding and consist of disseminated galena and sphalerite and lesser amounts of calcite, fluorite, baryte, pyrite and sericite forming a cement that fill interstitial pores in Neoproterozoic/Eocambrian (e.g. Laisvall) to Cambrian (e.g. Vassbo) sandstones. Deposits occur both in autochtonous and allochtonous sedimentary rocks, and a broad consensus exists about their epigenetic nature, their spatial relationships to syn-sedimentary faults and that ore fluids have scavenged metals from the crystalline basement. However, the detailed ore depositional history and the timing of ore deposition have remained more controversial. New analyses aimed to complement earlier Rb-Sr data (crush-leach technique using sphalerite) fail to support a published three-point isochron age of 467 +/- 5 Ma. This is probably due to syn-ore mixing between fluids carrying isotopically variable strontium and inherited problems to analyse sphalerite grains that strictly were deposited from a single ore pulse. Tentatively, strontium in the ores originate from a mix of components derived from the basement, seawater and the local sedimentary host sequences. The lead component has highly radiogenic compositions, and data define sub-parallel linear arrays interpreted to essentially represent mixing of isotopically different types of lead released from regional basement rocks. There are obvious similarities when comparing features of deposits representing two Pb-Zn ore styles, the sandstone-hosted dissemination and the fracture-controlled mineralisation in the granite-dominated basement occurring further east of the Caledonian margin. These include low temperature brines responsible for mineral deposition, the mineralogy and the nature of Rb-Sr and Pb isotope data. We suggest that these types of mineralisation have a common origin and time of emplacement, but it is elusive to propose a well-constrained age. Nonetheless, field observations and other evidence suggest that ore formation is due to large-scale fluid flow triggered by the transition from an extensional to compressional tectonic setting at about 500 Ma. Connected to this mid-Cambrian stage was the development of syn-sedimentary faults and fractures in the basement and in overlying consolidated sandstones. The opening of such zones of weakness enabled a movement of ore-forming fluids infilling pore space in sandstones (disseminated ore) and fractures in the basement (vein ore).

The sandstone-hosted Osen lead deposit, Norway: new Pb isotope evidence for sourcing in the underlying granitoid basement

This paper is focused on methodology and scientific interpretations by use of isotopes in heritage science—what can be done today, and what may be accomplished in the near future? Generally, isotopic compositions could be used to set time constraints on processes and manufacturing of objects (e.g. the 14C technique). Furthermore, isotopic compositions (e.g. Sr and Pb isotopes) are useful for tracing the origin of a component or a metal. The concepts isotope and isotopic fractionation are explained, and the use of stable respectively radioactive isotopes is exemplified. Elements which today have a large potential in heritage research are reviewed, and some recent and less known applications from the literature are summarized. Useful types of mass spectrometers are briefly described, and the need for reliable standards as well as accurate measurements and corrections is stressed. In future, further chemical elements may be utilized for isotope studies in heritage science, and possible candidates are discussed. The paper may in particular be valuable to readers less acquainted with the use of isotopic measurements. The many examples from referenced papers and also results from the authors’ studies in this field may inspire imaginative and inquisitive scientists to try new applications utilizing isotope data in heritage science.

Stratigraphy and ages of Palaeoproterozoic metavolcanic and metasedimentary rocks at Kaymajarvi, northern Sweden

Understanding geochemical processes in mining environments are essential to waste management decisions including remediation. In an attempt to understand geochemical processes, chemical data have m ...

The North-Western region of the Ukrainian Shield hosts numerous dykes varying widely in terms of their age and composition. One of the distinguished group of dykes embraces subalkaline basic rocks that belong to the Palaeoproterozoic (1815-1740 Ma) Korosten anorthosite-mangerite-charnockite-granite plutonic complex. Based on geological relationships with rocks of the Korosten complex and geochronological data, it is indicated that dykes were repeatedly emplaced at c. 1800, 1760 and 1750 Ma. Swamis of subalkaline limfrc dykes are also found at a large distance from the Korosten plutonic complex that indicates the large areal distribution of igneous activity of this type. In terms ofgeochemistry, these dykes are characterized by low #M.g (24.5-39), low SiO2 (46-54 wt. %), and highTiO(2) (1.7-3.8 wt. %), Ca (5-8 wt. %), 1(70 (1.0-3.1. wt. %), and P20, (up to 1.9 wt. %). Dykes of the Korosten complex are enriched in incompatible trace elements (Rb, Zr REE) and heavily depleted in compatible elements (Ni, Cr, Cu, V), and in strontium. The REF pattern is rather fractionated and [La/Yb]N varies from 5 to 14. eNd (1760 Ma) ranges from-1.6 to 1.6, while epsilon Sr (1760 Ma) varies from -5 to 19, with exception of two dykes that have much more radiogenic Sr isotope composition. The lead isotope composition embraces a wide range from unradiogenic (Pb-206/Pb-204 = 16.2) to radiogenic (Pb-206/Pb-204 = 20.2) values. The composition of rock-forming minerals in subalkaline dykes is close to that of anorthosites that constitute a major phase of the Korosten plutonic complex. This indicates that cumulative minerals of anorthosites had crystallized from melts that were close in composition to the subalkaline dykes. The evolution of the dyke chemistry is defined by the fractional crystallization of plagioclase and olivine. The residual melt. is getting enriched in those components that constitute K-feldspar and in incompatible elements that accumulate in the accessory minerals. The REE patterns suggest that the source of the initial melts for subalkaline matte dykes contained garnet-bearing rocks (eclogites?). The distribution of trace elements indicates a crustal origin of the primary melts. In terms of their composition, the dyke rocks of the Korosten plutonic complex are similar to jotunites that occur in the Rogaland anorthosite province, and in some other anorthosite provinces worldwide.

The Northern Norrbotten region, and in particular the Kiruna area, hosts a number of large apatite iron oxide deposits (e.g. the huge Kiirunavaara ore) of significant economic importance. Age data from rock lithologies hosting these ores, represented by metamorphosed rocks of the Porphyrite and Kiirunavaara Groups, are complex to interpret. This is illustrated by (LA-ICP-MS) data for titanite, and to some extent for rutile, which scatter considerably yielding ages within a span from ca. 2.1 Ga to 1.7 Ga. These analysed hydrothermal minerals, characterized by complex BSE images revealing darker and brighter zones, are located in ore zones and associated with e.g. strong scapolitisation, albitisation and actinolitisation. Previous (TIMS) zircon ages of host rocks, on the other hand, define a more narrower age interval between ca. 1900 and 1870 Ma, and this is supported by new U-Pb zircon results presented here. Furthermore, one coherent set of SIMS data for titanite from the Luossavaara ore favour that crystallization took place at ca 1.88 Ga, although laser ICP data from the same locality are much more complex. An implication arising from published pre-1.9 Ga laser ablation ages for titanites is that the emplacement of host rocks started already at around 2.1 Ga. As the depositional time of these rocks is crucial for the understanding of the overall crustal formation in northern Norrbotten, additional rocks were selected for age dating. New zircon age data (LA-ICP-MS and SIMS) give support to a scenario where host rocks to ores started to develop at around 1900 Ma and this calls for a re-evaluation of published LA-ICP-MS data of hydrothermal mineral phases. Here, we present four models that aim to explain how pre-1.9 Ga titanite ages, believed to have a questionable geological significance, may develop. The principal idea is that <= 2.1 Ga alteration events were not responsible for the crystallization of the hydrothermal minerals, instead it is believed that apparent old age domains carry excess radiogenic lead due to the effect of <= 1.9 Ga hydrothermal processes. Currently, the interpretation of U-Pb isotope data in the study area remains enigmatic, and further radiometric analyses are required.

This article presents the results of a comprehensive provenance study based on a combined geochemical-isotopic and archaeological approach, comprising 98 analyses of 97 copper-alloy objects from the Danish Bronze Age. When it comes to the question of the origin of the metal, our interpretations diverge somewhat from earlier established theories about the origin of copper imported to Denmark, which mainly pointed to Central and Eastern Europe. Clear geochronological patterns in the Danish dataset are interpreted as being due to shifts in ore sources; reflecting varying areas of origin as well as the utilization of varying ore types. This again relates to shifting trade networks/suppliers and shifting technological trends. Plausible sources for Danish copper-alloys identified in the current study are ore regions in the British Isles, Alpine ore districts in Italy and Austria, as well as ore regions in the western part of the Mediterranean and to some degree the Slovak Carpathians. The comparison includes hundreds of recently published lead isotope data for ores in Slovakia, the Iberian Peninsula and the Italian and Austrian Alps.

Medium- to high-grade metamorphosed, 1.9 Ga, stratiform, syngenetic Zn-Pb +/- Ag sulfide deposits constitute an economically important type of ore deposit in the Bergslagen lithotectonic unit of the Fennoscandian Shield. The Lovisa Zn-Pb deposit occurs in a metamorphosed succession of rhyolitic ash-siltstone, rhyolitic mass flow deposits, limestone, and Fe formation, deposited at a stage of waning volcanism in Bergslagen. Accessory graphite, absence of Ce anomalies in shale-normalized rare earth element (REE) data, and absence of hematite in Mn-rich Fe formations stratigraphically below the Lovisa Zn-Pb deposit indicate a suboxic-anoxic depositional environment. The uppermost Mn-rich Fe formation contains disseminated, inferred syngenetic Pb-Ag mineralization with mainly negative delta S-34 values in sphalerite and galena (-6.1 to -1.9 parts per thousand). Deposition of this Fe formation terminated during a pulse of explosive felsic volcanism. The Lovisa Zn-Pb deposit is interpreted to have formed in an alkali-rich brine pool developed immediately after this volcanic event, based on lithogeochemical and stratigraphic evidence. The first stage of mineralization deposited stratiform sphalerite mineralization with mainly positive delta S-34 values (-0.9 to 4.7 parts per thousand). This was succeeded by deposition of more sphalerite-galena stratiform mineralization with delta S-34 values close to 0%0 (-2.1 to 1.5 parts per thousand). The more galena-rich mineralization partitioned strain and was partly remobilized during later ductile deformation. The stratigraphic context, sulfide mineralogy, S isotopes, and alteration geochemistry suggest that the metal-liferous fluids and the depositional environment were H2S deficient (S poor or SO42- dominant). The source of S is interpreted to have In a mixture of H2S derived from bacterial and thermochemical seawater sulfate reduction and S derived from leaching of volcanic rocks, with the latter becoming more important over time. Lovisa formed in a setting where basin subsidence was periodically punctuated by the deposition of thick, syneruptive felsic volcaniclastic mass flow deposits. Coeval volcanism was likely important for driving hydrothermal activity and supplying a reservoir of metals and S. However, the high rate of deposition of volcaniclastic sediment in Bergslagen also precluded the establishment of long-lived, deep, and anoxic environments favorable for accumulation of organic matter and H2S. This stratigraphic pattern is common in Bergslagen and may explain why large stratiform Zn-Pb deposits are uncommon in the region and restricted to the uppermost part of the metavolcanic succession, directly stratigraphically beneath postvolcanic politic rocks.