The Role of Mineral Assemblages in the Environmental Impact of Cu-Sulfide Deposits: A Case Study from Norway

Metallic mineral deposits represent natural geochemical anomalies of economically valuable commodities but, at the same time, their weathering may have negative environmental implications. Cu-sulfide mineral deposits have been recognized as deposits with a particularly large environmental footprint. However, different Cu deposits may result in significantly different environmental impacts, mostly depending on weathering conditions, but also on geological characteristics (mineralogy, geochemistry, host-rock lithology) of the Cu mineralization. This study presents new mineral and geochemical data from the Repparfjord Tectonic Window sediment-hosted Cu deposits and the Caledonian volcanogenic massive sulfides (VMS) deposits. The deposits share similar mineral features, with chalcopyrite and bornite as the main ore minerals, but they differ according to their trace element composition, gangue mineralogy, and host lithology. The studied sedimenthosted Cu deposits are depleted in most toxic metals and metalloids like Zn, As, Cd, and Hg, whereas the Røros Caledonian VMS mineralization brings elevated concentrations of Zn, Cd, In, Bi, As, and Cd. The conducted leaching experiments were set to simulate on-land and submarine weathering conditions. A high redox potential was confirmed as the main driving force in the destabilization of Cu-sulfides. Galvanic reactions may also contribute to the destabilization of minerals with low rest potentials, like sphalerite and pyrrhotite, even under near-neutral or slightly alkaline conditions. In addition, the presence of carbonates under near-neutral to slightly alkaline conditions may increase the reactivity of Cu sulfides and mobilize Cu, most likely as CuCO3 (aq)

Geochemistry of sediment-hosted copper deposits and their environmental impact: A case study from the Nussir and Ulveryggen deposits, Repparfjord Tectonic Window, Northern Norway

Modern growing economy and technology require metals. Therefore mining is an unavoidable process. Mining in its turn results in the production of large amounts of mine waste. This research is focused on one type of mine waste, mine tailings, formed after the processing of Cu-sulphides deposits. Acid mine drainage (AMD) is a consequence of the oxidation of sulphide-rich rocks and has a drastic impact on the environment. In order to better understand the factors that can influence the rate of sulphides oxidation, a thorough investigation of primary ore and petrographic, mineralogical and geochemical characterization of host rocks was made on two sedimentary-hosted Cu deposits of Nussir and Ulveryggen in northern Norway. The exploitation of the Ulveryggen deposit in 1972-1978/79 resulted in mine tailings disposal in Repparfjorden. Mineralogical and geochemical investigation of marine sediments revealed that in spite of the fact that sulphides are generally well-preserved, some signs of AMD are present. To compare the submarine conditions of mine tailings disposal with on-land deposition, the Røros mining area, in Trøndelag, was chosen as a case study. Thermodynamical modeling was applied for determination of dissolved Cu speciation under the varying pH. The redox potential (Eh) is the major factor that influences the sulphides solubility while pH determines the dissolved species. In anoxic submarine conditions, the sulphides remain well-preserved, while in oxic atmospheric conditions, the strong weathering occurs. Laboratory weathering tests were conducted during 90-days period to simulate the oxidation of sulphides in the submarine and on-land conditions. Carbonates and/or organic matter were added to marine sediments or quarzitic sand and infiltrated with seaweater or meteoric freshwater. The results demonstrated that organic matter prevents oxidation while carbonates trigger the Cu-sulphides weathering

Geochemistry of sediment-hosted copper deposits and their environmental impact: A case study from the Nussir and Ulveryggen deposits, Repparfjord Tectonic Window, Northern Norway

Modern growing economy and technology require metals. Therefore mining is an unavoidable process. Mining in its turn results in the production of large amounts of mine waste. This research is focused on one type of mine waste, mine tailings, formed after the processing of Cu-sulphides deposits. Acid mine drainage (AMD) is a consequence of the oxidation of sulphide-rich rocks and has a drastic impact on the environment. In order to better understand the factors that can influence the rate of sulphides oxidation, a thorough investigation of primary ore and petrographic, mineralogical and geochemical characterization of host rocks was made on two sedimentary-hosted Cu deposits of Nussir and Ulveryggen in northern Norway. The exploitation of the Ulveryggen deposit in 1972-1978/79 resulted in mine tailings disposal in Repparfjorden. Mineralogical and geochemical investigation of marine sediments revealed that in spite of the fact that sulphides are generally well-preserved, some signs of AMD are present. To compare the submarine conditions of mine tailings disposal with on-land deposition, the Røros mining area, in Trøndelag, was chosen as a case study. Thermodynamical modeling was applied for determination of dissolved Cu speciation under the varying pH. The redox potential (Eh) is the major factor that influences the sulphides solubility while pH determines the dissolved species. In anoxic submarine conditions, the sulphides remain well-preserved, while in oxic atmospheric conditions, the strong weathering occurs. Laboratory weathering tests were conducted during 90-days period to simulate the oxidation of sulphides in the submarine and on-land conditions. Carbonates and/or organic matter were added to marine sediments or quarzitic sand and infiltrated with seaweater or meteoric freshwater. The results demonstrated that organic matter prevents oxidation while carbonates trigger the Cu-sulphides weathering

Stability of Cu-Sulfides in Submarine Tailing Disposals: A Case Study from Repparfjorden, Northern Norway

Mine tailings that were produced during the exploitation of the Ulveryggen siliciclastic sediment-hosted Cu deposit in northern Norway were disposed into the inner part of Repparfjorden from 1972 to 1978/1979. This study focuses on the mineralogy and geochemistry of the submarine mine tailings and underlying natural marine sediments from the inner part of Repparfjorden, as well as on the primary Ulveryggen ore. The ore mineralization from the neighboring Nussir carbonate sediment-hosted Cu deposit was studied too, due to the forthcoming mining of both deposits. Bornite and chalcopyrite are the major Cu-sulfides, and are characterized by low concentrations of potentially toxic elements including Cd, Hg, and As. The tailing material occupies the uppermost 9 cm of Repparfjorden sediments. It is characterized by predomination of a silty component with elevated Cu (up to 747.7 ppm), Ni (up to 87 ppm), and Cr (up to 417 ppm) concentrations. The high Cu concentration is related to the deposition of mine tailings. In contrast, Ni and Cr concentrations are close to those in naturally occurring stream sediments from the feeding river, Repparfjordelva, reflecting the compatibility of these elements with hosting mafic volcanics, which are widely spread in the Repparfjord Tectonic Window. Copper in the uppermost part of the sediments is bound to the acid-soluble fraction while Ni and Cr are bound to the residual fraction. Artificial placement of large masses of fine-grained material, i.e., smothering, resulted in a diminished biological activity and/or physical distortion of mostly benthic fauna, which was reflected in total organic carbon (TOC) values as low as 0.15% in the uppermost strata. Sulfide minerals are found both in natural marine sediments and in the mine tailings. They are generally well-preserved with an exception for chalcopyrite from the uppermost part of the submarine tailing, which shows signs of incipient weathering. Thermodynamic modeling confirmed that redox potential and pH are important factors in the weathering of sulfides. Available ligands contribute to the Cu speciation. In near-neutral to slightly alkaline conditions a presence of carbonates can lead to the mobilization of Cu in form of CuCO3 complexes

The Nussir copper deposit: petrology, mineralogy, geochemistry and distribution of ore mineralization

The geology, petrography, mineralogy and geochemistry of the Nussir copper deposit in Finnmark, Northern Norway were studied during writing this thesis. The Nussir deposit of copper is a sedimentary-hosted hydrothermal deposit affected by low grade methamorphism and ductile deformation. The copper mineralization includes chalcopyrite, chalcocite, bornite, covellite, and digenite. The deposit contains also economically interesting trace elements, such as silver, gold, and PGE. The deposit shows a vertical zonation of ore minerals, accordingly from top to bottom: pyrite, chalcopyrite, silver minerals, galena→bornite→digenite, chalcocite, and covellite

Biogeochemical impact of historical submarine mine tailings on benthic ecosystems in the Repparfjord (Northern Norway)

Historical copper mine tailings deposited in the Repparfjord, Northern Norway, provided new insight into the biogeochemical impact of submarine tailings disposals on high-latitude coastal ecosystems. The submarine tailings disposal in the Repparfjord represents a product of mining activities between 1972 and 1979. Their environmental impact has been extensively studied during the last decade, but geochemistry of the sediment pore water, which is crucial to assess and monitor the in-situ metal leaching and bioavailability, has never been analysed. The actual impact on the benthic fauna remains poorly known. Therefore, this study couples the pore water chemistry and the foraminiferal analysis obtained from selected sediment cores (gravity core, multicore, box cores) to examine metal stability and the past and current status of the foraminifera community. We measured down-core sulfate and trace metal concentrations and Eh-Ph and applied the Shannon index, the AZTI's Marine Biotic Index (F-AMBI) index and the foraminiferal abnormality index. This study confirms the ongoing leaching of copper from the underlying mine tailings and release across the sediment-water interface. Leaching of Ni, Zn and Pb have been attributed to weathering of natural bedrock lithologies. The original benthic foraminiferal community disappeared almost entirely during the disposal period, and now it is dominated by stress-tolerant and opportunistic species like Bulimina marginata and Spiroplectammina biformis. Anyhow, against previous assumptions, the community composition changed, while the overall diversity and abnormalities (FAI) shell formation is unaffected by elevated copper concentrations

Interaction of chitosan with hydrogel of poly(acrylic acid) and preparation of encapsulated drugs.

The complexation of linear chitosan with hydrogel of poly(acrylic acid) was studied in acetic acid solutions. It was found that the complexation is accompanied by contraction of hydrogel samples with formation of turbid layer on their surface. The dynamic changes of swelling ratio of poly(acrylic acid) hydrogel in course of the interaction with chitosan are interpreted from the diffusion theory point of view considering the properties of double electric layer on hydrogel-solution boundary. The FTIR spectroscopy method revealed the electrostatic mechanism of interaction between poly(acrylic acid) hydrogel and chitosan. The spectrum of polycomplex shows the bands, which are characteristic for both poly(acrylic acid) (1725, 1450, 1249 cm-1) and chitosan (1648, 1536, 1165, 1091, 1023 cm-1) confirming the sorption of the later polymer by hydrogel of poly(acrylic acid). The possibility of encapsulation of antibiotic levomycetin into polycomplex hydrogels as well as its release from the capsules has been studied. It was found that the maximal value of the drug released from the polycomplex capsule is achieved after the longer period in comparison with control experiment with its release from pure PAA hydrogel. It was shown that the interpolymer interactions between oppositely charged linear polymers and hydrogels could be successfully used for preparation of encapsulated forms of various physiologically active substances

Evolution of metal-bearing fluids at the Nussir and Ulveryggen sediment-hosted Cu deposits, Repparfjord Tectonic Window, northern Norway

The Palaeoproterozoic greenstone belts of Fennoscandia are metamorphosed and deformed volcanic and sedimentary rocks that formed in basins with a high base-metal ore potential. One of these, the Repparfjord Tectonic Window (RTW), is exposed in the Caledonides of northern Norway and contains several sediment-hosted Cu deposits including Nussir and Ulveryggen. The RTW is composed of mafic metavolcanic rocks (metabasalts, volcanoclastic metabreccia and metatuffite) intercalated with carbonate-siliciclastic sedimentary rocks (dolomitic marble, metasandstone to metapelite). This succession was deformed and metamorphosed up to greenschist to lower amphibolite facies during the Svecofennian Orogeny (c. 1.84 Ga). The Cu-mineralisation at the Nussir deposit is hosted by a dolomitic marble. It occurs mostly in the form of quartz-carbonate veins with chalcopyrite, bornite, chalcocite and covellite as the main ore minerals. In contrast, the Ulveryggen mineralisation is predominantly disseminated within a metasiliciclastic succession and dominated by chalcopyrite, bornite, chalcocite, covellite and neodigenite. Mineralogical, geochemical, stable isotope and fluid-inclusion studies provide insights into the evolution of the Cu-bearing fluids. A wide range in homogenisation temperatures (135–350°C at the Nussir deposit and 102–520°C at the Ulveryggen deposit) and fluid-inclusion salinities (from 0.35 up to 36 wt.% NaCl equivalents) suggest an evolving system with brines developed by subsurface evaporite dissolution. Fluid-inclusion and Cu-sphalerite geothermometry data constrain the temperature-pressure conditions of the Cu mineralisation in the Nussir deposit at 330–340°C and 1.1–2.7 kbars. High salinities at relatively high temperatures within the ore-bearing fluids imply that Cu was transported predominantly by Cu-chloride complexes. The interaction of ore-bearing fluids with carbonate-rich host lithologies is proposed as the main mechanism for deposition of the Cu mineralisation at Nussir. In contrast, at the Ulveryggen deposit the mineralisation was mostly controlled by dilution and cooling when ore-bearing fluids mixed with groundwaters. Locally, reaction of Cu-bearing fluids with sediment-hosted pyrite might also have triggered copper precipitation. Similar ranges of δ13C (- 0.9 to + 2.9‰ V-PDB) and δ18O (- 18.3 to - 15.9‰ V-PDB) values in carbonates from ore-bearing veins and underlying host dolomitic marbles reflect a carbonate rock-buffered system without a significant contribution of magmatic or hydrothermal CO2

Stability of Cu-Sulfides in Submarine Tailing Disposals: A Case Study from Repparfjorden, Northern Norway

Mine tailings that were produced during the exploitation of the Ulveryggen siliciclastic sediment-hosted Cu deposit in northern Norway were disposed into the inner part of Repparfjorden from 1972 to 1978/1979. This study focuses on the mineralogy and geochemistry of the submarine mine tailings and underlying natural marine sediments from the inner part of Repparfjorden, as well as on the primary Ulveryggen ore. The ore mineralization from the neighboring Nussir carbonate sediment-hosted Cu deposit was studied too, due to the forthcoming mining of both deposits. Bornite and chalcopyrite are the major Cu-sulfides, and are characterized by low concentrations of potentially toxic elements including Cd, Hg, and As. The tailing material occupies the uppermost 9 cm of Repparfjorden sediments. It is characterized by predomination of a silty component with elevated Cu (up to 747.7 ppm), Ni (up to 87 ppm), and Cr (up to 417 ppm) concentrations. The high Cu concentration is related to the deposition of mine tailings. In contrast, Ni and Cr concentrations are close to those in naturally occurring stream sediments from the feeding river, Repparfjordelva, reflecting the compatibility of these elements with hosting mafic volcanics, which are widely spread in the Repparfjord Tectonic Window. Copper in the uppermost part of the sediments is bound to the acid-soluble fraction while Ni and Cr are bound to the residual fraction. Artificial placement of large masses of fine-grained material, i.e., smothering, resulted in a diminished biological activity and/or physical distortion of mostly benthic fauna, which was reflected in total organic carbon (TOC) values as low as 0.15% in the uppermost strata. Sulfide minerals are found both in natural marine sediments and in the mine tailings. They are generally well-preserved with an exception for chalcopyrite from the uppermost part of the submarine tailing, which shows signs of incipient weathering. Thermodynamic modeling confirmed that redox potential and pH are important factors in the weathering of sulfides. Available ligands contribute to the Cu speciation. In near-neutral to slightly alkaline conditions a presence of carbonates can lead to the mobilization of Cu in form of CuCO3 complexes