A new ore province, the Gold Line, southwest of the Skellefte District, northern Sweden, is currently under exploration. The largest known deposit in the Gold Line is the hypozonal Fäboliden orogenic gold deposit. The mineralization is hosted by arsenopyrite-bearing quartz veins, within a steep shear zone in amphibolite facies metagreywacke host rocks. Gold occur in fractures and as intergrowths in arsenopyrite-löllingite, and as free grains in the silicate matrix of the host rock. The hydrothermal mineral assemblage in the proximal alteration zone is diopside, calcic amphibole, biotite, and minor andalusite and tourmaline. Primary fluid inclusions in the Fäboliden quartz veins show a CO2-CH4 or a H2S (±CH4) composition (the latter recognized for the first time in a Swedish ore deposit). The primary fluid inclusions are associated with arsenopyrite-löllingite (+gold) and the CO2-CH4 fluid was also involved in precipitation of graphite. A prevalence of carbonic over aqueous fluid inclusions is characteristic for a number of hypozonal high-temperature orogenic gold deposits. The Fäboliden deposit, thus, shows fluid compositions similar to other hypozonal orogenic gold deposits. The proposed main mechanism for precipitation of gold from the fluids, is a mixing between H2S-rich and H2O?-CO2±CH4 fluids. Fluid inclusion data indicate arsenopyrite-löllingite and graphite deposition at a pressure condition of about 4 kbar. Graphite thermometry indicates maximum temperatures of 520-560°C for the hydrothermal alteration at Fäboliden, suggesting that at least the late stages of the mineralizing event took place shortly after peak-metamorphism in the area, i.e. at c. 1.80 Ga.

The Orvar Hill formation in Tiveden, south-central Sweden, constitutes a unique low-strain window of well preserved Svecofennian mafic volcanic rocks on the southwestern border of the Svecokarelian orogen. The area can be considered as the southwestern border of the Bergslagen region of the Svecokarelian orogen. The Orvar Hill formation consists of coherent pillowed and non-pillowed basalts alternating with mafic volcaniclastic racks in the lower part of the Lindberga supracrustal succession. Only minor felsic volcanic rocks occur in the upper part. Quartz-bearing metagreywackes comprise the top part of the Lindberga supracrustal succession. Geochemistry of lavas and volcaniclastic rocks suggests that the Orvar Hill mafic volcanic rocks were emplaced in a volcanic-are setting. This demonstrates that the Tiveden supracrustal units probably formed in response to volcanism related to subduction. The Tiveden area may thus represent a 1.89 Ga primitive, sediment-starved volcanic are at the margin of the continental volcanic are of the Bergslagen district. The relationship between Tiveden and Bergslagen at the time of formation is not clear and Tiveden may represent a remnant of an are that accreted to a continent at c. 1.88-1.86 Ga.

Microwave plasma (MWP) and inductively coupled plasma (ICP) have been used as excitation sources in spectroscopic analyses. The results show that MWP and ICP sources are excellent for spectroscopic determinations of a large number of major, minor and trace constituents in various geological materials. The low detection limits, the restricted matrix effects and the large number of elements that can easily be determined in a single process make MWP and ICP spectroscopy superior to atomic absorption and X-ray spectroscopy in many geochemical studies.

The Swedish contribution to the International Geodynamics Project (IGP) is concentrated in two major fields of research, the Caledonian Research Project and the Study of Postglacial Earth.Movements. Both projects are financed by the Swedish Natural Science Research Council This paper summarizes the research activities of the Caledonian Research Project (CRP). The IGP-CRP is an inter-disciplinary study involving geologists and geophysicists with a wide range of interests and drawn from institutions in Göteborg, Lund, Luleå, Stockholm and Uppsala. Various collaborative projects with foreign institutions are in progress. Research is concentrated geographically in a Geotraverse some 300 km long and 200 km wide, extending from the Caledonian Front in the vicinity of Östersund to the Norwegian coast west of Trondheim. CRP research is organized in nine subprojects, namely, Basement and Deep Structure, Basement—Cover Relationships, the Särv Nappe, the Seve—Köli Nappe Complex and Higher Tectonic Units, Pre-orogenic History, Palaeo-magnetism, Experimental and Theoretical Tectonics, Experimental and Theoretical Studies of the Mechanism of Rock Deformation, and Experimental and Theoretical Studies of Metamorphism within the Geotraverse Area. Priority is given to research leading to a better understanding of crustal movements during the Caledonian evolution, during both the accumulation of the late Pre-Cambrian to Devonian sequences and their orogenic deformation.

The Dannemora supracrustal inlier is located in the north-eastern part of the Bergslagen region in south-central Sweden and hosts the second largest iron ore deposit in the region. The metasupracrustal succession of the inlier consists of c. 1.9 Ga Palaeoproterozoic rocks that are mainly sub-alkaline, rhyolitic to dacitic, pyroclastic deposits, reworked pyroclastic deposits and metalimestone. It is c. 700-800-m thick and termed the Dannemora Formation. The formation is divided into lower and upper members and the former is in turn subdivided into subunits 1 and 2. The great thickness of individual pyroclastic deposits indicates deposition within a caldera. The rocks show characteristics of a pyroclastic origin by containing abundant pumice, cuspate and Y-shaped former glass shards, and fragmented crystals of quartz and subordinate feldspars. Scattered spherulites and lack of welding-compacted fiamme suggest that the lower member was slightly welded, where as the upper member contains sericite-replaced glass shards with preserved primary shapes indicating no welding. Undisturbed layers of ash-siltstone with normal grading and fluid-escape structures are attributed to subaqueous deposition below storm wave base in the eastern part of the inlier, where as erosion channels and cross-bedding in some of the volcaniclastic deposits imply deposition and reworking above wave base in the central part of the inlier. Epidote spots, previously interpreted as altered limestone fragments and an indicator for subaquatic deposition, are here reinterpreted as the result of selective alteration related to the intrusion of mafic dykes and to Ca release during dolomitisation of limestone.

The Tjårrojåkka area is located about 50 km WSW of Kiruna, northern Sweden, and hosts one of the best examples of spatially and possibly genetically related Fe-oxide and Cu-Au occurrences in the area. The bedrock is dominated by intermediate and basic extrusive and intrusive rocks. An andesite constrains the ages of these rocks with a U-Pb LA-ICPMS age of 1878±7 Ma. They are cut by dolerites, which acted as feeder dykes for the overlying basalts. Based on geochemistry and the obtained age the andesites and basaltic andesites can be correlated with the 1.9 Ga intermediate volcanic rocks of the Svecofennian Porphyrite Group in northern Sweden. They formed during subduction-related magmatism in a volcanic arc environment on the Archaean continental margin above the Kiruna Greenstone Group. Chemically the basalts and associated dolerites have the same signature, but cannot directly be related to any known basaltic unit in northern Sweden. The basalts show only minor contamination of continental crust and may represent a local extensional event in a subaquatic back arc setting with extrusion of mantle derived magma. The intrusive rocks range from gabbro to quartz-monzodiorite in composition. The area is metamorphosed at epidote-amphibolite facies and has been affected by scapolite, K-feldspar, epidote, and albite alteration that is more intense in the vicinity of deformation zones and mineral deposits. Three events of deformation have been distinguished in the area. D1 brittle-ductile deformation created NE-SW-striking steep foliation corresponding with the strike of the Tjårrojåkka-Fe and Cu deposits and was followed by the development of an E-W deformation zone (D2). A compressional event (D3), possible involving thrusting from the SW, produced folds in the central part of the area and a NNW-SSE striking deformation zone in NE.

A palaeomagnetic and geochemical study has been performed on basic dykes in northern Sweden. The dykes and a gabbro formation were sampled in 28 sites and characteristic magnetizations could be defined in 23 of them. The dykes form a part of a swarm that trends in NE-SW to E-W. From differences in palaeomagnetic signatures and composition it is concluded that this swarm is composed of two generations of dykes, group A and B, trending in similar directions. The dykes of group A have compositions that are similar to rapakivi related dykes, while those of group B are different from most rapakivi dykes in Fennoscandia. The calculated pole positions may suggest that the group B dykes are older than those of group A and both groups intruded within the time span 1.77 Ga to 1.50 Ga. The trend of the dykes is more or less parallell to a palaeo-compressional stress field that may be expected from the collisional tectonics related to the Gothian orogeny. The intrusion of the rapakivi formations in Fennoscandia has been suggested to be related with the Gothian orogeny and the intrusion of the dykes may thus be guided by the stress field generated by the collisional tectonics.

The Svärdsjö Zn-Pb-Cu deposit is situated in the heavily mineralised Bergslagen lithotectonic unit of the Fennoscandian shield, south-central Sweden. Intense hydrothermal alteration followed by a strong overprint by deformation and metamorphism during the Svecokarelian orogeny complicate interpretation of the local geology. Integration of whole-rock lithogeochemical and petrographic methods has allowed the mainly dacitic volcanic host succession and effects of ore-related hydrothermal alteration to be characterised. Mineralisation is hosted by 2–15 m thick, commonly skarn-altered dolomitic marble interbeds. Zones of strong–intense hydrothermal chlorite-sericite alteration envelop the marble units, recording mass gains of Fe and Mg, as well as Na depletion. Minerals such as cordierite, anthophyllite and sillimanite formed in these rocks during regional metamorphism. Mineralisation via sub-seafloor replacement is suggested for the deposit based on alteration zoning and the irregular, stratabound, marble-hosted style of sulphide lenses. It is inferred that mineralisation formed via neutralisation of hot, acidic metalliferous fluids. Geochemically and lithologically distinct units adjacent to the mineralised zones can serve as marker units to aid further exploration in the area. Mass change calculations reveal that Fe and Mg enrichment, as well as Na depletion exhibit detectable changes extending up to 100 m from the mineralised lenses, providing exploration vectors.

The origin of the more than 100 km wide Lycksele ring structure in Sweden has puzzled geoscientists for years. In this short note we present results from field analysis, detailed sampling and laboratory analysis executed in search for evidence of an impact, e.g. shatter cones and shock features in minerals. Both approaches gave negative results and consequently an impact origin could neither be confirmed nor rejected. The circular structure of the Lycksele ring and its central uplift are, however, typical features of large, complex impact structures.

A structural investigation of the Sala Zn–Pb–Ag deposit in the Bergslagen mining district of southern Sweden shows that it is associated with two tectonic structures: the N–NW-trending Storgruveskölen shear zone (SSZ), which is parallel to the strike of the mined ore bodies, and the F1 Sala syncline with a fold hinge plunging c. 35° towards NNW, which is parallel to the plunge of the entire mineralised system. The Sala syncline was refolded by F2 folds, leading to flattening and local reversals in the plunge of F1 folds and the ore bodies. Field evidence suggests that the SSZ represents both a phase of D3 reverse dip-slip shearing and a later (D4) phase of dextral strike-slip reactivation. However, a high concentration of pre- to syn-D1skarn- and sulphide-bearing vein networks and breccias adjacent to the SSZ, which are gradational into the mined massive sulphide ore bodies, suggest that stages in the formation of the SSZ predated D3 and D4. It may consequently constitute a reactivated pre- to syn-D1 structure. The distribution of breccia and hydrothermal alteration together with the highly discordant nature of the deposit are consistent with a pre- to syn-D1 timing of ore formation, involving of cross-stratal fluid flow along the proto-SSZ and subordinate fluid flow parallel to volcanic interbeds in the host carbonate rock. Three δ34S determinations on sphalerite (2.1–2.4‰) and galena (1.2‰), respectively, are consistent with a magmatic source for ore sulphur, as has been suggested for many other sulphide deposits in Bergslagen.

The timing of Palaeoproterozoic magmatism in the Garpenberg area in the Bergslagen region of the Fennoscandian shield has been constrained by secondary ion mass spectrometry (SIMS) U-Pb zircon dating of metamorphosed igneous rocks. Volcanism is constrained by igneous crystallisation ages of 1895 ± 4Ma for a syn-volcanic rhyolite porphyry intrusion and 1893 ± 3Ma for a rhyolitic pumice breccia. Granite and microgranodiorite, which intruded into the stratigraphy, are dated at 1895 ± 3 and 1894 ± 4 Ma, respectively. The identical U-Pb ages suggest rapid geological evolution from the emplacement of volcanics, their burial and subsidence to 2-5 km depths and intrusion by granitoids. The timing of metamorphism and the extent of metamorphic resetting of titanite have been evaluated. SIMS titanite 207Pb-206Pb ages from the same samples as the zircon yield younger ages. Although errors are large in individual analyses and fractions, a weighted average of 59 analyses from four samples yields a 207Pb-206Pb age of 1858 ± 14 Ma, interpreted as the age of regional metamorphism. The results add constraints to the timing of sulphide and iron oxide mineralisation at Garpenberg. The rhyolite porphyry is intruded into a syngenetic iron formation. Its crystallisation age provides a minimum age for syngenetic iron oxide deposits at Garpenberg. The major Zn-Pb sulphide deposits are accompanied by alteration envelopes. Units formed before alteration yield similar igneous crystallisation ages as intrusions post-dating alteration. It is concluded that both iron oxide and sulphide mineralisation formed within the same age-span as the dated units.

We address controls on Co and Ni distribution, based on their solubility in hydrothermal fluids as functions of pH, ƒO₂ and T, in two end-member types of sulphide deposits in Bergslagen, Sweden. Oxidized hydrothermal fluids, as have been suggested for the formation of the Zinkgruvan deposit, would efficiently transport Co and Ni in solution, even at 150 ^oC. Formation of Co and Ni sulphides and sulphosalts supersedes or overlaps the precipitation of other sulphides along a reduction or H₂S-mixing path. This is consistent with the presence of Co and Ni sulphides and sulphosalts in vent-proximal Cu-Zn mineralization at Zinkgruvan.

Reduced, acidic and hot (≥250 ^oC) hydrothermal fluids that have been invoked for the formation of deposits like Falun and Stollberg could also transport Co and Ni in solution. However, their solubility is strongly dependent on high T and low pH. Cooling and neutralization are here proposed as likely key triggers for the deposition of Co and Ni, yet, unlike in the Zinkgruvan scenario, saturation will occur within the pyrite stability field, whereby these metals may be sequestered as stoichiometric lattice substitutions in pyrite and other sulphides rather than forming minerals of their own.

We conclude that at any T or realistic pH, hydrothermal systems involving oxidized brines have a greater ability to traverse and leach large rock volumes of Co and Ni. Consequently, areas hosting deposits that formed from such brines have a significant exploration potential for these metals, even in areas where Co-enriched source rocks are lacking or subordinate.

The Zinkgruvan deposit has been included in compilations of exceptionally Ga- and Ge-endowed deposits in Sweden. Available published data sets do however not support a substantial enrichment in Ga and Ge. In this contribution, we investigate the Ga- and Ge-endowment based on a whole-rock lithogeochemical data and ore grade analyses from the deposit. Based on our results, we find it highly unlikely that a Ga-endowment exists in the ore. A Ge-endowment may exist, but we find no evidence of Ge grades at the 1,000 ppm level that have been reported previously.

During the last stages of the Weichselian glaciation (ca. 9,000-15,000 years B.P.), reduced ice loads and glacially affected stress fields resulted in active faulting in Fennoscandia with fault scarps up to 160 km long and up to 30m high. These postglacial (PG) faults are usually SE dipping, SW-NE oriented thrusts, and represent reactivated, pre-existing crustal discontinuities. Postglacial faulting indicates that the glacio-isostatic compensation is not only a gradual viscoelastic phenomenon, but also includes unexpected violent earthquakes, suggestively larger than other known earthquakes in stable continental regions. We explore here possibilities and benefits for investigating, via scientific drilling, the characteristics of postglacial faults in northern Fennoscandia, including their structure and rock properties, present and past seismic activity and state of stress, as well as hydrogeology and associated deep biosphere. The research is anticipated to advance science in neotectonics, hydrogeology and deep biosphere studies, and provide important information for nuclear waste disposal, petroleum exploration on the Norwegian continental shelf and studies of mineral resources in PG fault areas.

The Jokkmokk granitoid is exposed in a large plutonic massif northwest of Jokkmokk in northern Sweden. It is light grey to white, fine-grained, with megacrysts of feldspar and glomeroporphyritic hornblende and biotite. Small enclaves of mafic rocks and synplutonic mafic dykes are products of mingling with a coeval and possibly cogenetic mafic magma. The Jokkmokk granitoid was previously considered to belong to the c. 1.8 Ga Lina S-type intrusive suite, but the Jokkmokk granitoid has a unique calc-alkaline to alkali-calcic, metaluminous to weakly peraluminous, character with a moderate LREE enrichment and a flat HREE pattern, and a flat to slightly positive Eu-anomaly. U–Pb TIMS zircon dating of the Jokkmokk granitoid gives an age of 1883±15 Ma which is coeval with the emplacement of the Haparanda suite, but contrary to the Haparanda suite it displays a positive _Nd(t) value of 2.8, indicating a more juvenile Palaeoproterozoic character similar to the Jörn suite in the Skellefte district. This type of magma seems to be restricted to the palaeoboundary between the Archaean craton in the north and Palaeoproterozoic juvenile crust in the south. Spatial correlation with low angle, south dipping, WNW-trending shear zones and NNE-trending subvertical shear zones, highlight the possibility that this unique magma type is related to transtension in the overriding plate and partial melting in a sub-arc mantle wedge during NE-directed subduction processes related to the early stages of the Svecokarelian orogen. This type of setting has been advocated as the potentially most favourable tectonic setting for porphyry copper formation.

The Ni‐Cu ore bearing Lainijaur intrusion is situated in the northern part of the Palaeoproterozoic Skellefte ore district in northern Sweden. The lowest part of the intrusion is composed of gabbroic rocks that pass upwards into granodiorite. At the bottom of the gabbro, two linear, pyrrhotite dominated, sulphide bodies occur. Geochemical data indicate a comagmatic suite, including olivine gabbro, ophitic gabbro, quartz diorite, and granodiorite. The olivine gabbro is a cumulate of olivine, pyroxene, and plagioclase. Analytical data of the remaining parts of the suite show a consistent differentiation trend when plotted in variation diagrams. The different rock types were emplaced during several pulses of magma injection; the gabbroic rocks formed first. The cumulative olivine gabbro, containing the highest amounts of sulphides, was not formed in situ, but accumulated and was transported from a deeper magma chamber. The parent magma was a Cu‐ and Ni‐rich, low‐Ti tholeiite with a flat REE‐pattern; in classification diagrams exhibiting an LKT to WPB character. North of the Skellefte district, several other intrusions are found which exhibit similarities to Lainijaur. Available data indicate that they were formed in an extensional environment at the end of the major 1890–1870 Ma magmatic event in the area.

The 1.85-1.67 Ga Transscandinavian Igneous Belt (TIB) forms a major Paleoproterozoic igneous complex in the western part of the Fennoscandian Shield. Different tectonic models propose that the TIB was formed in a tectonic regime governed either by compression or by extension. This paper presents an analysis of anisotropy of magnetic susceptibility (AMS) and paleomagnetic data from the Rätan granite (1.70 Ga), which forms a large pluton in the central part of the TIB. The major aim of the study is to test the existing tectonic models and to define a paleomagnetic pole position for the Rätan granite. Three contrasting magnetic fabric domains are identified. In the eastern and western domains the AMS fabric is characterized by NW-SE to N-S trending subvertical foliation planes and a girdle distribution of the maximum and intermediate anisotropy axes. The central domain is characterized by subhorizontal magnetic foliation planes and lineations that cluster in a NW-SE trending direction. We suggest that the Rätan granite was emplaced in a tectonic regime governed by NW-SE directed extension and that the pluton was fed obliquely with a magma source situated to the present northwest. A positive baked contact test is demonstrated for a basic dyke suggesting that the Rätan granite has not been remagnetized since c. 1.6 Ga. A paleomagnetic formation mean direction is defined for the granite (decl. = 2°, incl. = 59°) that yields a paleopole position of Plat = 67° and Plon = 190°.

An anisotropy of magnetic susceptibility (AMS) and paleomagnetic study has been performed on post-Jotnian basic sills of the Ulvö complex, of the Central Scandinavian Dolerite Group (CSDG). The CSDG intruded some 1.27 Ga ago in the central part of the Fennoscandian Shield and extends over an area of c. 150 000 km2. Previously presented AMS data of the CSDG sills from southcentral and northern Sweden indicated a NW or SE directed magma flow. In this study new measurements of the AMS reveal a fairly uniform pattern of NW-SE lineation directions also for the dolerites of the Ulvö complex. While the magma is flowing in a dyke or a sill, elongated particles become imbricated against the chilled margins, and the AMS can be used to determine not only the lineation but also the true direction of the magma flow. An imbrication pattern defined for one of the sills suggests that the magma propagated from the present NW towards SE. The established paleomagnetic pole position (Plat=-3° and Plon=157°) is in very good agreement with other paleomagnetic data from the Ulvö complex and from other parts of the CSDG. The new AMS data from the Ulvö complex presented in this study fit well in to the magnetic fabric pattern previously presented for the CSDG sills and support a plate tectonic model suggesting that the CSDG is a related to the break up of Baltica from Laurentia at c. 1.27 Ga ago.

Patterns seen in coarse gabbroid with dykes of both mafic and felsic compositions are described, giving insight into rheological behaviour of injections at different stages of cooling

The geographical subdivision between the Haparanda and the Jörn suites of intrusive rocks in northern Sweden has not been very well defined. Early stratigraphical schemes placed these two granitoid suites in two separate orogenic cycles, where the Jörn belonged to the older cycle and Haparanda to the younger. Our present knowledge regarding the isotopic ages of these rocks in northern Sweden has changed this view, but has also made the distinction between the two suites less clear. Based on recent Sm–Nd isotopic work combined with geochemistry and some new U–Pb zircon data, we point out some similarities as well as some differences between the Jörn and Haparanda suites of rocks. Two U–Pb zircon age determinations performed give upper intercept ages of 1891±32 Ma and 1861±19 Ma which are interpreted as maximum ages. The two samples are taken from the Luleå area, on each side of the Archaean–Proterozoic boundary, as defined by Sm–Nd isotopic analyses of c.1.9 Ga old intrusive rocks combined with the southern limit of outcropping Archaean rocks. On the basis of new results together with results from previous studies of areas north and south of the Archaean–Proterozoic boundary, we also suggest how to separate the Haparanda and Jörn suites of rocks due to their geochemical, and isotope geochemical, characteristics. The Haparanda suite generally has negative εNd(t) values and was formed within or in marginal parts of the Archaean craton. The Jörn suite was formed in an juvenile, island-arc terrane, that was accreted to the Archaean craton during the later, collisional stages of the Svecokarelian orogeny. In a similar way, we connect the Haparanda suite of rocks with the Archaean craton, and the Jörn suite of rocks with Svecofennian juvenile crust.

Pre-existing bedrock structures that reactivated following deglaciation through a combination of tectonic and isostatic stresses are well documented in northern Fennoscandia. Due to their possible implications for seismic hazards, there is a need to document the locations and geometries of these features. The recent availability of a high-resolution, LiDAR-derived, digital elevation model coveringmost of Sweden provides an ideal base upon which to map post-glacial fault scarps that appear to crosscut glacial sediments and landforms. The current mapping project has identified new post-glacial fault scarps in central Sweden, and both refined and rejected scarps previously mapped by aerial photographicinterpretation in northern Sweden. No post-glacial fault scarps, however, were identified in southern Sweden. The current inventory of post-glacial fault scarps is available for download and will be updated as more data become available.

The four Maurliden massive to network sulphide deposits are hosted by a silicic volcanic succession in the Palaeoproterozoic Maurliden domain in the central part of the Skellefte district, northern Sweden. The bedrock in the Maurliden domain can be divided into primary volcanic rocks and volcaniclastic sedimentary rocks. The primary volcanic rocks comprise coherent rhyolitic, dacitic, andesitic and mafic volcanic facies and their related autoclastic and pumiceous breccia facies. The volcaniclastic sedimentary rocks include monomict to slightly polymict breccia-conglomerates, which are related to terrestrial to shallow marine erosion of domes, and sandstone turbidites and mudstones, which indicate submarine settings below wave base. The primary volcanic rocks and volcaniclastic sedimentary rocks collectively define a submarine volcanic centre. This volcanic centre was characterized by the emplacement of rhyolitic domes and cryptodomes, accompanied by subordinate explosive activity. It was developed in the ensialic back-arc or intra-arc basin of the Skellefte district. The facies architecture shows that prior to massive sulphide deposition, feldspar porphyritic rhyolitic volcanism, and both terrestrial/shallow marine and below wave base environments characterized the volcanic centre. At the time of massive sulphide deposition the Maurliden volcanic centre was characterized by quartz-feldspar porphyritic rhyolite volcanism and below wave base environment. This volcanism resulted in strongly quartz-feldspar porphyritic rhyolite cryptodomes, domes and quartz-feldspar porphyritic pumice breccia-sandstone (QFP pumice unit). The QFP pumice unit erupted explosively and was rapidly sedimented on the sea floor as a series of subaqueous mass-flows. All four Maurliden sulphide deposits are hosted within this QFP pumice unit, which suggest a genetic connection between eruption of the QFP pumice unit and formation of the sulphide deposits.

Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) has been used to determine the concentrations of 17 trace elements (V, Mn, Cu, Zn, Rb, Sr, Mo, Ag, Cd, Sb, Ba, Ce, Tl, Pb, B, Th, and U) in magnetite from the Kiirunavaara iron deposit in northern Sweden. Magnetite grains were sampled from four different parts of the concentrating plant. An attempt was made to investigate if there are any concentration differences between the surface layer and interior layers in magnetite grains, using a two-stage soft ablation procedure. Possible non-representative sampling due to fractionation, was evaluated by using a polished in-house calibration standard. The two-stage ablation showed no significant differences between the first and second layer, in terms of elemental compositions. Concentrations of V (up to 2300 µg/g) and Mn (up to 7850 µg/g) are the most abundant trace elements encountered. Cu, Zn, and Pb are among the less common trace elements in magnetite. The conversion of intensity signals of the elements to concentration values mg/g was achieved by using a polished in-house magnetite standard and Fe for internal standardization.

It is generally assumed that c. 1.9 Ga ago the northern part of the Fennoscandian (Baltic) Shield comprised a continental margin along which plate tectonism and subduction took place. The main division of the region is a marine domain towards the south and a continental domain towards the north. At Bure in northern Sweden, the marine-continental transition is exposed and the lithologies and palaeotectonic environment of this area are investigated in the present paper. The results show that the former lithostratigraphic division has to be modified and a reconstruction of the geological development is necessary. The Bure supracrustal sequence shows a successive change from a marine schist-greywacke-basaltic environment in the stratigraphically lowest part (Stalo Formation) to a continental volcanic environment in the upper part (Bure Formation). The continental volcanic rocks are intermediate-felsic and mildly alkaline. Minor intercalations of similar volcanic rocks occur within the marine sequence. The youngest event in the Bure area is the deposition of the Loito Formation which consists of a red conglomerate-sandstone lying on top of the Bure and Stalo volcanic rocks. The chemical character and lithological associations infer that the Bure Formation volcanic rocks were deposited in an extensional environment and may constitute the late stage member of the calc-alkaline volcanism that occurs further east, the Arvidsjaur Porphyries. Continental bimodal and slightly alkaline volcanic rocks occur north and northwest of the Bure area and would, together with the continental Bure volcanic rocks, form a separate group, here collectively referred to as the Arjeplog Porphyries

Recent foundation and rock-excavation works have shown that the gneiss bedrock in the harbour area of Karlshamn is clay-weathered. Swelling clay minerals form part of the weathering products and this has created a number of practical problems, the choice of a suitable foundation pressure to avoid heaving being the most important one. This requires the prediction of a reasonably safe value of the swelling pressure and it is shown that the Yong & Warkentin theory can be used for this purpose, provided that the density of the clay mass is fairly moderate and that the particle orientation is taken into consideration. □ Engineering geology, foundations, settlement, rock excavation, clay-weathered gneiss, weathering, swelling clay, heaving, ground pressure, swelling pressure.

The Kuså orthomagmatic Ni-Cu sulphide deposit is situated c. 13 km west of Falun in Bergslagen, southcentral Sweden. Ion probe data on zircon from the mafic to ultra-mafic host rocks yield a 207Pb/206Pb weighted average age of 1798 ± 4 Ma, suggesting a genetic connection to intrusive activity forming theTransscandinavian Igneous Belt (TIB-1 phase). TIB-1 ages have recently been reported also for the Kleva deposit of similar type in Southern Sweden. The presence of these two occurrences suggests prospectivity potential for Ni-Cu mineralisation in mafic to ultramafic members of the areally extensive TIB.

The Sjangeli supracrustal belt occurs at the eastern margin of the Rombak-Sjangeli basement culmination that involves Proterozoic basement, which became incorporated into the Caledonian orogen as old basement faults were reactivated. The lead isotopic composition of early Proterozoic marbles from the Sjangeli supracrustal belt fall in the ²⁰⁶Pb/²⁰⁴Pb-²⁰⁷Pb/²⁰⁴Pb diagram on a linear array that is interpreted as a mixing line. Using the age of granite intrusion and Proterozoic metamorphism as source age for the lead (t1≈ 1.8 Ga), the corresponding mixing age is t1≈ 0.4 Ga, which suggests that the radiogenic lead was introduced during the Caledonian deformation of the marbles. The isotopic compositions of lead and strontium, which also is highly variable and radiogenic, are positively correlated, indicating that radiogenic lead and strontium were introduced together. Combining lead and strontium isotope data from the marbles and Paleozoic galena-calcite veins demonstrates that the lead and strontium were derived from local sources with isotopically distinct characteristics. Sample suites from deformed marbles that define linear arrays in the ²⁰⁶pb/²⁰⁴pb-²⁰⁷pb/²⁰⁴pb diagram probably represent mixing lines rather than secondary isochrons.

Differences between U‐Pb zircon and Rb‐Sr whole‐rock ages are often interpreted to be due to later geologic disturbances such as low‐grade metamorphism and slow cooling. Yet, apparently contrasting ages can also be due to erroneous ages derived from non‐ideal systems. Their incorporation into geological models results in distorted time scales and may ultimately lead to the suggestion of geologic processes and events that are not real. I illustrate this point discussing the geochronologic database that originally was used (1) to constrain the evolution of silicic crust in the Svecofennian area, (2) to define the geographic extent of the Sveconorwegian‐Grenville orogeny in north Norway and east Greenland, (3) to determine the age of thrusting in the southern Swedish Caledonides, and (4) to confine the Apparent Polar Wander Path (APWP) of the Baltic Shield.

Rare-element pegmatites at Stora Vika are emplaced in gneisses and a metamorphosed carbonate layer. Earlier geochronologic investigations gave a U-Pb zircon age of 1854±5 Ma (2ω), which originally was interpreted to be the age of emplacement, and a Rb-Sr whole-rock isochron of 1777±12 Ma (1ω). The U-Pb zircon age is in conflict with the U-Pb columbite age of 1785±3 Ma (2ω) for another pegmatite from the same swarm. It is argued that the U-Pb zircon age is strongly influenced by inherited zircon and therefore lacks geologic relevance

The age of migmatitic granites that form in response to crustal thickening after large collision events provides a minimum estimate for the end of subduction-related processes and the beginning of crustal thickening. Migmatitic granites in south-central Sweden are bracketed in age by two major phases of granitoid magmatism: 1.89-1.85 Ga arc-related magmatism and 1.80-1.77 Ga post-kinematic and post-metamorphic magmatism.The migmatitic granite at Köping yields a U-Pb monazite age of 1846 +- 1 Ma and is the oldest so far identified anatectic granite south-central Sweden. Its age demonstrates that: 1) subduction processes ceased before ca. 1.85 Ga, 2) migmatite granites in south-central Sweden have the same age as corresponding rocks in southern Finland, and 3) this type of granite seems to be distinctly older in south-central Sweden than corresponding rock in the Bothnian Basin. The 1846 +/- 1 Ma of the migmatitic granite at Köping extends the previously recognized age zonation in geochemically related pegmatites to comprise also migmatitic granites. This age zonation indicates for corresponding rocks older ages to the south, and may be interpreted to be indicative for earlier collision and crustal thickening of the Svecofennian region in the south.

The Yxsjoberg scheelite-skarn deposit of western Bergslagen (south-central Sweden) formed in Palaeoproterozoic time when aqueous fluids migrating along lithologic discontinuities replaced limestones in acid volcanic rocks. The age of the mineralization and, thus, the source of the fluids are controversial. U-Pb dating of titanite that formed during the skarnification of the limestones yields an age of 1789+ or -2 Ma. This age is not compatible with an exhalative origin of the deposit or a genetic relation to Svecofennian arc magmatism, as has been suggested. Instead, the U-Pb titanite age corresponds to the age of Y, Rb, F, and Nb-rich post-kinematic granitoids from the Bergslagen area and granitoids of the Transscandinavian Igneous Belt (TIB) farther to the west. As the TIB granitoids are not fertile with respect to W-mineralizations, the U-Pb titanite age indicates that the post-kinematic granitoids were the source of heat, metals, and probably fluids for the formation of the Yxsjoberg scheelite-skarn deposit

The low-grade Aitik Cu-Au-Ag deposit is a deformed and metamorphosed porphyry-type deposit, and as such it belongs to the group of ores that require detailed mineralogical investigations of precious metal occurrences to assist in determining the recovery processes. The character of gold in the Aitik deposit varies substantially. Gold alloys display highly variable Au/(Au + Ag) ratios, and Hg is commonly a constituent. A change from dominantly sulphide-associated to groundmass-associated gold as mining progresses towards depth is accompanied by a change in the chemical composition of gold. Towards depth, the gold content in electrum and amalgam decreases (from c. 66 to 22% in electrum and c. 23 to 4% in amalgam), and the amount of native gold grains increases. The most common mineral assemblage associated with gold at deep levels (600m and below) is K-feldspar, biotite, plagioclase, quartz, chalcopyrite and pyrite. This study demonstrates that magmatic-hydrothermal and metamorphic processes responsible for the diversity in copper mineralisation styles within the Aitik ore body probably have also played a role in the variable character of gold observed at Aitik today

Petrographical and lithogeochemical investigations in combination with mapping in the Gällivare area, northern Norrbotten, Sweden, have led to the identification of several igneous intrusive rock types. These include: (1) ultramafic-mafic complexes, (2) mafic-intermediate rocks, (3) dolerites and (4) felsic plutons. The ultramafic-mafic rocks include the ca. 1.88 Ga Dundret complex and ca. 1.80 Ga Vassaravaara complex. The Dundret complex has tholeiitic to calc-alkaline affinity, shows a primitive mineral content and was formed in an extensional tectonic setting. The Vassaravaara complex has a similar chemical signature as the Dundret complex. The mafic-intermediate plutons vary in composition from gabbro to diorite. The chemical signature of the dioritic rocks indicate formation in a volcanic arc setting. Dolerites occur as solitary dikes and have calc-alkaline affinity. The felsic plutons include granite and syenite of ca. 1.88, 1.80 and 1.78 Ga age. The felsic plutons have calc-alkaline to shoshonitic affinity and mostly show a metaluminous I-type character. Results indicate subduction at 1.90 Ga resulting in a volcanic arc system, and including extensional events generating back-arc environments leading to mafic, intermediate and felsic magmatism in the Gällivare area. Subduction at 1.80 Ga is suggested to have caused a similar process generating mafic and felsic magmatic rocks in the same area. A subsequent collision event finally generated 1.78 Ga granitic rocks.

An attempt is made to correlate the chemical compositions of certain minerals from different parts of fold structures with the theoretical stress pattern. A partial analysis was made on amphibole, plagioclase, garnet, diopside, sphalerite and biotite with a microprobe and the theoretical stress pattern was calculated by means of the finite-element method (FEM). Two of the four fold structures investigated show a systematic variation in the chemistry of some minerals, but there is no simple relationship to the theoretical stress model. The Fe-Mg silicates from the hinge zones often show lower values of iron, compared with the rest of the structure. A systematic variation between co-existing minerals indicates that chemical equilibrium has been attained. In many cases, the studied minerals from a folded layer are quite constant, which may be due either to small pressure gradients or to the fact that we have chosen minerals and elements which are not very sensitive to pressure. Though stress-induced diffusion may create some chemical variations, small fluctuations in partial pressures and local chemistry will very soon mask this pattern.

Subhorizontal joints filled with sediments were found at Forsmark in north-eastern Uppland, Sweden. The sediments are glacial in character and show varves, graded and current bedding, and clay laminae. The occurrence, structure and pollen frequency of the sediments imply a deposition during a Pre-Holocene age, possibly during Early or Middle Weichsel.

The Aitik Cu-Au-Ag deposit in northern Sweden is hosted by strongly altered and deformed 1.9 Ga old Svecofennian volcaniclastic rocks. A porphyritic quartz monzodiorite intrusion of subvolcanic origin is situated in the structural footwall to the ore. U-Pb TIMS zircon dating of the quartz monzodiorite yielded an age of 1887±8 Ma, which coincides with the age obtained for the subduction-related Haparanda suite of granitoids in Norrbotten. It is intruded by minor, comagmatic phases, including units of finer grained quartz monzodiorite and diorite. The finer grained intrusive phase, which can be traced into the ore zone of the Aitik deposit, is believed to represent apophyses protruding from the upper part of the quartz monzodiorite. The Aitik intrusion, comprising the quartz monzodiorite and its comagmatic phases, is affected by regional metamorphism, deformation, and hydrothermal alteration. Potassic alteration is most evident, and expressed by the growth of secondary biotite and K-feldspar. The sub-economic Cu-Au-Ag mineralization hosted by the Aitik intrusion mainly consists of chalcopyrite, pyrite, and magnetite of dominantly magmatic-hydrothermal origin, and is present in four forms: disseminated, as veinlets, in quartz-feldspar veins, and in biotite-amphibole veins. This mineralization extends in economic grades into the adjacent volcaniclastic rocks in the roof of the intrusion. The Aitik intrusion is similar in many respects to porphyry copper generating intrusions regarding tectonic setting, petrography and chemical composition. The intrusion-hosted sub-economic mineralization might form part of a porphyry system with its major part represented by the main mineralization in the overlying volcaniclastic rocks.

The Liikavaara Östra Cu-(W-Au) deposit is situated close to the operating Aitik Cu-Au mine in northern Sweden. It is scheduled for production in 2023. Modern geological descriptions of the deposit are lacking though knowledge of geological and mineralogical details prior to operation is beneficial to avoid surprises. In this study, petrological, mineralogical and geochemical investigations of the wall rocks, host rock and mineralisation, and zircon U-Pb analysis of a footwall granodioritic intrusion were carried out. The mineralisation is hosted by quartz±tourmaline-calcite veins, calcite veins and aplite dykes that cross-cut biotite-amphibole schists and gneisses. The wall rocks to the ore are metavolcaniclastic rocks of basaltic to andesitic composition. A granodiorite intrusion occurs in the footwall. The mineralisation is mainly chalcopyrite, pyrrhotite and pyrite with some sphalerite, galena, scheelite, molybdenite and magnetite. It shows slight enrichments in Au, Ag and Bi. Gold and Ag occur as electrum and Ag also in hessite and an Ag-sulphide. The Bi mineralogy includes native Bi, Bi-tellurides and Bi-sulphides. These minerals are found as inclusions, along the borders of and in cracks in chalcopyrite, pyrite, pyrrhotite, sphalerite, molybdenite and quartz. The footwall granodiorite intrusion was dated at 1.87 Ga. It is suggested here to be the source for ore genesis based on its spatial relation to the mineralisation, as well as on high-salinity fluids and metal composition of the ore. The aplite dykes may have acted as pathways for the magmatic hydrothermal fluids that carried the metals from the intrusion to the host rock.

The Skellefte 1.9 Ga volcanic arc in northern Sweden is one of the most mineralized (VMS, orogenic gold, mafic hosted Ni, porhyry style Cu-Au) Palaeoproterozoic arc systems in the world. The Skellefte District is interpreted to have accreted, or formed as a continental volcanic arc system, during accretionary processes related to the Svecokarelian Orogeny. Based on Sm-Nd isotope studies it has been concluded that the basement to the ore-bearing Skellefte Group cannot be much older than the volcanic arc and was thus probably juvenile Palaeoproterozoic crust. The basement is not known to outcrop and recently it was speculated, based on high resolution seismic work in the western part of the district, that the basement is dipping gently northwards beneath the ore-bearing Skellefte Group. It was further postulated from these studies that the basement could at least partly constitute the Bothnian supergroup, metasedimentary rocks that outcrop south of the Skellefte District. Part of this supergroup has been dated at 1.95 Ga. For economic reasons it is extremely important to understand the 3-dimensional extent of the Skellefte Group and this constitutes one direct aim of a future deep drilling proposal. The basic scientific aim for the drilling project is to better understand the accretionary processes that constitute the Svecokarelian Orogeny. One of the best places to study these processes is the Skellefte District where well preserved volcanic rocks form an arc system on the older Karelian Craton margin. A drilling programme in the Skellefte District will thus benefit the exploration and mining industry directly and at the same time address fundamental questions related to the tectonic processes that built the Fennoscandian Shield during one of the most intense orogenic periods in the evolution of the earth, between 1.95 and 1.80 Ga.

The three main intrusive suites: early calc-alkaline, late I/Atype, and late S-type intrusive rocks in relation to the Svecokarelian orogeny (1.9–1.8 Ga) have been dated at the Archaean craton margin in the Palaeoproterozoic Skellefte district and surrounding areas in northern Sweden. In addition, new SIMS data have been obtained on a calcalkaline intrusion for which unusually young TIMS ages existed, compared to similar calc-alkaline intrusions elsewhere in the region. Titanite and zircon from a subvolcanic intrusion affected by a major N–S trending shear zone have also been dated to constrain the last ductile deformation in the area. The 1895+14–12 Ma zircon age for a calc-alkaline intrusion is interpreted as the crystallisation age and is significantly older than the existing 1825 Ma age on titanite from a pyroxene skarn in a marble horizon close to the contact. The latter age is instead interpreted as the age of peak metamorphism in this area. The 1798±4 Ma age for the S-type granite confirms that the S-type magmatism is largely coeval with the I/A type magmatism previously dated at 1803±6 Ma. At a larger scale, a zoned belt over 2000 km long with A/I-type magmatism in the west and S-type magmatism in the east can be inferred. Either mafic underplating or Cordilleran type settings can explain the magmatic belt, which trends oblique to the roughly NE-directed subduction that led to the accretion of volcanic arcs onto the older craton between 1.95 and 1.87 Ga. An intimate temporal relationship between the extensive 1.80 Ga magmatism and regional N–S-trending shear zones in the area is confirmed by the titanite age of c. 1.80 Ga from one such shear zone. Kinematics on this shear zone suggest E–W shortening. SIMS data from a calc-alkaline intrusion at Sikträsk indicate that the previously obtained conventional zircon ages of 1.85–1.86 Ga are actually mixed ages of 1.88 Ga magmatic zircons, and c. 1.80 to 1.82 Ga metamorphic overgrowths. This shows that the 1.80 Ga event was not only constrained to shear zones. It is argued that both the 1.80 to 1.82 Ga deformation and metamorphism discussed here is related to E-W shortening and the voluminous magmatism at 1.82–1.80 Ga. This is in contrast to the older c. 1.88 Ga deformation identified to the north and east within the Karelian craton that was related to Svecokarelian accretionary processes.

The Palaeoproterozoic, c. 1.88 Ga old Långdal VHMS deposit is situated in the eastern part of the Skellefte District, northern Sweden. In the stratigraphic footwall to the VHMS ore a sulphidequartz vein system with high gold grades was mined in the second half of the 1990’s. The Långdal VHMS ore is hosted by the uppermost part of the Skellefte Group volcanic rocks, close to the contact with an overlying fine-grained sedimentary unit. Regional structural studies indicate that bedding surfaces in volcanic rocks are parallel to the contact between the volcanic and the sedimentary rocks. Based on the differences in structural style on each side, the contact is interpreted as a major structural break. The Långdal ore is situated close to this break that may have focussed fluid flow during metamorphism and deformation. The orientation of the contact indicates that it either is a D2 structure or that it was at least active during D2. The structural development in the altered footwall rocks to the Långdal VHMS ore indicates that gold-bearing sulphide and sulphide-quartz veins both pre- and post-date the first deformation. Gold associated with the vein system can thus not only be attributed to syngenetic exhalative or replacement processes. The close spatial relationship with the massive sulphide deposits suggests, however, that the gold was remobilized from these syngenetic systems. It is concluded that sulphides were introduced at several stages during the geological evolution of the area as: a) syngenetic disseminations of sulphide and folded, pre-S1 stringer sulphide±quartz veins in the footwall related to the syngenetic VHMS deposit, b) syn-S1 sulphide veins in the footwall gold ore, c) main, post-S1, sulphide-quartz veins associated with the gold ore in the footwall rocks to the Långdal VHMS deposit, and d) post-S1 to pre-S2 galena and sphalerite rich veins post-dating the main, post-S1, sulphide-quartz vein system in the footwall to the Långdal ore. From these relationships it is suggested that gold was re-mobilized from the sulphide rich parts of the VHMS system into post-D1 structures during or slightly after the peak metamorphism. The timing of this event is poorly constrained to post-date the syngenetic ore emplacement by 20–80 m.y.

Geochemical studies of pore water and groundwater in sulphide-bearing tailings have been performed at the Laver mine in northern Sweden. Pore water has been sampled from just above the groundwater table down to the peat and till underlying the tailings. Groundwater has been sampled weekly from April to November in pipes installed at various depths in the tailings. All samples were analysed for major and trace elements by using ICP-AES and ICP-MS. When the oxidation front in the tailings is moving downwards, metals released by weathering in this low-pH environment are to a large extent retained secondarily in the tailings below the oxidation front and do not reach the groundwater, except in areas where the oxidation front is situated close to the groundwater table. Vertical flow of precipitation water contaminated with metals released by sulphide oxidation is, thus, not the major explanation for groundwater contamination. Instead, contamination occurs when the advancing oxidation front pushes the secondary enrichments of metals ahead to meet the groundwater table and the metals are released to the groundwater. The release of metals is caused by desorption due to the low pH in this environment. Areas of the tailings deposit with shallow groundwater table are at present the main sources of metal release. There is a seasonal variation in the composition of groundwater, particularly shallow groundwater. This is caused by changing levels of the groundwater table. Rising groundwater table results in outflush of metals in areas where the groundwater reaches secondarily retained metals. A steady trend with rising groundwater table after snowmelt results in a larger proportion of contaminated water in shallow groundwater, which decreases during the autumn. Concentration peaks of Cu and other metals in shallow groundwater may be the result of small, rapid rises of the groundwater table due to strong precipitation, superimposed on the general seasonal trend.

Two major types of late Svecofennian granitoids occur in south central Sweden. Large homogeneous massifs of coarse-grained granite with trace element characteristics typical of granites formed in tensional settings occur along the Central Swedish Gravity Low (CSGL). The other type comprises smaller intrusions of irregular, heterogeneous, locally derived granites (IHLD granites). We present U-Pb zircon ages are presented of one IHLD granite and of three varieties of the homogeneous intrusions. The result for the IHLD granite is 1779+-8 Ma. One of the samples of the homogeneous type yielded an age of 1769.7 +- 3.4 Ma. The remaining two samples have heterogeneous zircon populations. The emplacement age of these rocks is bracketed by the intercept ages of 1770 +- 6 and 1779 +- 23 Ma.The overlapping ages of granite groups of different types show that different types of granites were formed contemporaneously in the same region as a result of melt formation at various depths and from various sources.