Mining industry generates a significant amount of waste including waste rock and tailings. The disposal of mine tailings has environmental impacts, such as the releasing of heavy metals to surface and underground waters. Therefore, adequate rehabilitation of mining waste storage facilities is essential. Abandoned tailings ponds may contain significant amounts of valuable minerals, including critical raw materials, and offer opportunities as secondary mineral resources. In this study geochemical and mineralogical characterization were made for the diverse mine tailings of the Rautuvaara tailings pond which was the final disposal site for different ore deposits. The samples were collected from two different locations in the tailings pond, preconcentrated and analysed with several methods including PSA, XRD, FE-SEM, EPMA, pXRF, WD-XRF and AAS. The geochemical results indicate substantially elevated Cu, As, Ni and Zn concentrations in the tailings. Mineralogical investigations revealed that the tailings contain valuable minerals such as gold, cobaltite, and W-bearing rutile. The last could be used as an indicator mineral in tailings classification and possibly also in future ore exploration. The study of secondary mineralogy revealed that the most weathered top layers of the tailings show secondary alteration rims on the surfaces of mineral particles, and the enrichment of As and Ni in the Fe- and Mn-oxide minerals.
{"title":"Geochemical and mineralogical characterization of mine tailings at the Rautuvaara mine site and aspects to environmental conditions and resource potential","authors":"Mitro Juutinen, Markku Seitsaari, P. Sarala","doi":"10.17741/bgsf/95.1.005","DOIUrl":"https://doi.org/10.17741/bgsf/95.1.005","url":null,"abstract":"Mining industry generates a significant amount of waste including waste rock and tailings. The disposal of mine tailings has environmental impacts, such as the releasing of heavy metals to surface and underground waters. Therefore, adequate rehabilitation of mining waste storage facilities is essential. Abandoned tailings ponds may contain significant amounts of valuable minerals, including critical raw materials, and offer opportunities as secondary mineral resources. In this study geochemical and mineralogical characterization were made for the diverse mine tailings of the Rautuvaara tailings pond which was the final disposal site for different ore deposits. The samples were collected from two different locations in the tailings pond, preconcentrated and analysed with several methods including PSA, XRD, FE-SEM, EPMA, pXRF, WD-XRF and AAS. The geochemical results indicate substantially elevated Cu, As, Ni and Zn concentrations in the tailings. Mineralogical investigations revealed that the tailings contain valuable minerals such as gold, cobaltite, and W-bearing rutile. The last could be used as an indicator mineral in tailings classification and possibly also in future ore exploration. The study of secondary mineralogy revealed that the most weathered top layers of the tailings show secondary alteration rims on the surfaces of mineral particles, and the enrichment of As and Ni in the Fe- and Mn-oxide minerals.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48008767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Nordbäck, Nikolas Ovaskainen, M. Markovaara‐Koivisto, P. Skyttä, A. Ojala, Jon Engström, C. Nixon
Fracture studies commonly lack data for the length range between 10 m to 1 km. For this reason, scaling laws are required to extrapolate fracture properties, for example in discrete fracture network models. This study focused on analysis and correlation of topology, orientation and length distribution of multiscale fracture datasets to assess their scalability. The used datasets comprise UAV-derived photogrammetric models from natural outcrops and lineaments mapped using airborne LiDAR, bathymetry and aerogeophysical data, in several contrasting scales and resolutions. This study highlights challenges in acquiring uncensored and coherent brittle structural datasets from source data characterized by a large span of resolutions between the remote sensing datasets and models of the fractured outcrop. In specific, collected data was found to be potentially biased and affected by uncertainties related to both the censoring by sedimentary cover and the scale of observation. Our results revealed differences between lineament and outcrop fracture orientations, as well as difficulties in assessing topological parameters from lineament datasets. The 1:200000 resolution was found best suited to the mapping of lineament length and resulted in a length distribution power law exponent of -1.92. For outcrop fractures that are less than 2 m long, the lognormal length distribution provided the only good fit to our data, while the longer outcrop fractures fitted relatively well with a power law exponent of -2.26.
{"title":"Multiscale mapping and scaling analysis of the censored brittle structural framework within the crystalline bedrock of southern Finland","authors":"N. Nordbäck, Nikolas Ovaskainen, M. Markovaara‐Koivisto, P. Skyttä, A. Ojala, Jon Engström, C. Nixon","doi":"10.17741/bgsf/95.1.001","DOIUrl":"https://doi.org/10.17741/bgsf/95.1.001","url":null,"abstract":"Fracture studies commonly lack data for the length range between 10 m to 1 km. For this reason, scaling laws are required to extrapolate fracture properties, for example in discrete fracture network models. This study focused on analysis and correlation of topology, orientation and length distribution of multiscale fracture datasets to assess their scalability. The used datasets comprise UAV-derived photogrammetric models from natural outcrops and lineaments mapped using airborne LiDAR, bathymetry and aerogeophysical data, in several contrasting scales and resolutions. This study highlights challenges in acquiring uncensored and coherent brittle structural datasets from source data characterized by a large span of resolutions between the remote sensing datasets and models of the fractured outcrop. In specific, collected data was found to be potentially biased and affected by uncertainties related to both the censoring by sedimentary cover and the scale of observation. Our results revealed differences between lineament and outcrop fracture orientations, as well as difficulties in assessing topological parameters from lineament datasets. The 1:200000 resolution was found best suited to the mapping of lineament length and resulted in a length distribution power law exponent of -1.92. For outcrop fractures that are less than 2 m long, the lognormal length distribution provided the only good fit to our data, while the longer outcrop fractures fitted relatively well with a power law exponent of -2.26.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44313356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Modern techniques for detrital mineral provenance were applied to sediment core 96/12-1pc from the Lomonosov Ridge in the central Arctic Ocean. The techniques include quantitative clay mineralogy analysis combined with determination of Nd, Pb, and Sr isotopes from clay fraction. The clay mineral assemblage and the isotope signatures depict distinct changes during the Marine Isotope Stage (MIS) 4-3 transition corresponding to the Middle Weichselian deglaciation. This transition is characterised by a homogenous, 48 cm thick, dark grey, silty clay layer with a distinctive IRD concentration, forming a prominent marker bed for the central Arctic Ocean sediments. The elevated smectite and kaolinite contents in the transitional interval are possible weathering products of the Siberian basaltic rocks, such as the Putorana Plateau, feeding the shelves of the Kara Sea and the western Laptev Sea. The Nd and Sr isotope values are compatible with input from the basaltic rocks and fall within the isotopic range of sediments from these shelves. The abrupt changes in the Nd, Pb and Sr isotopic data from the distinct grey layer attributed to the MIS 4-3 transition likely mark a pronounced deglaciation event. An increase in coarse debris in the grey layer indicates a change in the sedimentation regime with a strong iceberg rafting component. This change may also be related to a sudden release of meltwater from a large ice-dammed lake in the northern Siberia.
{"title":"Clay mineral and Nd, Pb, and Sr isotope provenance of a MIS 4-3 sediment record from the Lomonosov Ridge, central Arctic Ocean","authors":"Raisa Alatarvas, Ninna Immonen, K. Strand","doi":"10.17741/bgsf/95.1.003","DOIUrl":"https://doi.org/10.17741/bgsf/95.1.003","url":null,"abstract":"Modern techniques for detrital mineral provenance were applied to sediment core 96/12-1pc from the Lomonosov Ridge in the central Arctic Ocean. The techniques include quantitative clay mineralogy analysis combined with determination of Nd, Pb, and Sr isotopes from clay fraction. The clay mineral assemblage and the isotope signatures depict distinct changes during the Marine Isotope Stage (MIS) 4-3 transition corresponding to the Middle Weichselian deglaciation. This transition is characterised by a homogenous, 48 cm thick, dark grey, silty clay layer with a distinctive IRD concentration, forming a prominent marker bed for the central Arctic Ocean sediments. The elevated smectite and kaolinite contents in the transitional interval are possible weathering products of the Siberian basaltic rocks, such as the Putorana Plateau, feeding the shelves of the Kara Sea and the western Laptev Sea. The Nd and Sr isotope values are compatible with input from the basaltic rocks and fall within the isotopic range of sediments from these shelves. The abrupt changes in the Nd, Pb and Sr isotopic data from the distinct grey layer attributed to the MIS 4-3 transition likely mark a pronounced deglaciation event. An increase in coarse debris in the grey layer indicates a change in the sedimentation regime with a strong iceberg rafting component. This change may also be related to a sudden release of meltwater from a large ice-dammed lake in the northern Siberia.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44780794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Digital elevation models, based on laser scanning imageries (LiDAR-DEM) and aided by ground penetrating radar (GPR) data, were used to study glaciofluvial Gilbert-type ice-contact deltas in the Younger Dryas Salpausselkä end-moraine zone in southern Finland. The geomorphological data analysed were used to reconstruct the water-level drop of the late glacial Baltic Ice Lake to the early Holocene Yoldia Sea and tie these changes to a wider stratigraphic context. The results indicate that the sudden drainage event at around 11 650 cal. yrs BP left its imprint not only on the varved sediments but also on ice-contact glaciofluvial deltas in the Second Salpausselkä zone throughout southern Finland. This morphostratigraphic boundary can be placed at locations where the ice-contact deltas occur at two different levels; the higher-level deltas formed during the Baltic Ice Lake B III water-level stage and the lower-level deltas during the Yoldia Sea Y I water-level stage. This morphostratigraphically defined boundary in southern Finland marks the Pleistocene/Holocene chronostratigraphic boundary in southern Finland and shows the corresponding positions of the Scandinavian Ice Sheet’s Finnish Lake District Ice Lobe and the Baltic Sea Ice Lobe.
{"title":"The morphostratigraphic imprint of the Baltic Ice Lake drainage event in southern Finland","authors":"J. Lunkka","doi":"10.17741/bgsf/95.1.004","DOIUrl":"https://doi.org/10.17741/bgsf/95.1.004","url":null,"abstract":"Digital elevation models, based on laser scanning imageries (LiDAR-DEM) and aided by ground penetrating radar (GPR) data, were used to study glaciofluvial Gilbert-type ice-contact deltas in the Younger Dryas Salpausselkä end-moraine zone in southern Finland. The geomorphological data analysed were used to reconstruct the water-level drop of the late glacial Baltic Ice Lake to the early Holocene Yoldia Sea and tie these changes to a wider stratigraphic context. The results indicate that the sudden drainage event at around 11 650 cal. yrs BP left its imprint not only on the varved sediments but also on ice-contact glaciofluvial deltas in the Second Salpausselkä zone throughout southern Finland. This morphostratigraphic boundary can be placed at locations where the ice-contact deltas occur at two different levels; the higher-level deltas formed during the Baltic Ice Lake B III water-level stage and the lower-level deltas during the Yoldia Sea Y I water-level stage. This morphostratigraphically defined boundary in southern Finland marks the Pleistocene/Holocene chronostratigraphic boundary in southern Finland and shows the corresponding positions of the Scandinavian Ice Sheet’s Finnish Lake District Ice Lobe and the Baltic Sea Ice Lobe.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43333437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Editorial: The 3rd PalaeoArc 2022 Conference in Finland","authors":"P. Sarala","doi":"10.17741/bgsf/95.1.002","DOIUrl":"https://doi.org/10.17741/bgsf/95.1.002","url":null,"abstract":"","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46909806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Tiira, T. Janik, T. Veikkolainen, K. Komminaho, T. Skrzynik, Sakari Väkevä, A. Heinonen
We present results from a deep seismic sounding (DSS) experiment carried out along the southern coast of Finland in summer 2015. Data used in the survey derived from industrial blasts recorded by temporary project stations and permanent network stations. The western 220 km part of the 450 km long Southern Finland Coastal (SOFIC) profile runs along the Uusimaa belt (UB) in the 1.7–1.9 Ga Southern Finland subprovince (SFS) of the Svecofennian domain, while the 170 km part in the east crosses the 1.62–1.65 Ga Wiborg rapakivi batholith (WRB). The farthest 60 km cross a geologically diverse area consisting of supracrustal rocks and granitoids of the Saimaa area (SA), an eastern extension of the SFS. Our results show that the Moho boundary depth varies significantly, from ca. 52–54 km below UB to 40–45 km below WRB. All three crustal layers (upper, middle, and lower) have their maximum depth in the contact zone between UB and the WRB. Below WRB, a lower crust with Vp ~6.7–6.9 km/s is observed. High velocity lower crust was observed below UB (Vp ~7.2 km/s) and possibly below SA (Vp ~7.35 km/s). The modelling was based on ray tracing, using the extrapolation of seismic wave arrival times with the help of travel times predicted from a one-dimensional velocity model. The resulting two-dimensional velocity model partly relies on data from the intersecting DSS profiles and supports previous observations of the lithospheric structure of southeastern Fennoscandia.
我们介绍了2015年夏天在芬兰南部海岸进行的深地震测深（DSS）实验的结果。调查中使用的数据来源于临时项目站和永久网络站记录的工业爆炸。450公里长的芬兰南部海岸（SOFIC）剖面的西部220公里部分沿Svecofennian域1.7–1.9 Ga芬兰南部子省（SFS）的Uusimaa带（UB）延伸，而东部170公里部分穿过1.62–1.65 Ga Wiborg rapakivi岩基（WRB）。最远的60 km穿过由Saimaa地区（SA）的表壳岩石和花岗岩组成的地质多样性区域，该地区是SFS的东部延伸。我们的结果表明，莫霍边界深度变化很大，从UB下方52–54公里到WRB下方40–45公里不等。所有三个地壳层（上部、中部和下部）在UB和WRB之间的接触带中具有最大深度。在WRB下方，观测到Vp~6.7–6.9 km/s的下地壳。在UB以下（Vp~7.2km/s）和SA以下（Vp ~7.35km/s）观测到高速下地壳。建模基于射线追踪，利用一维速度模型预测的传播时间对地震波到达时间进行外推。由此产生的二维速度模型部分依赖于相交DSS剖面的数据，并支持先前对芬诺斯坎迪亚东南部岩石圈结构的观测。
{"title":"Implications on crustal structure from the South Finland Coastal (SOFIC) deep seismic sounding profile","authors":"T. Tiira, T. Janik, T. Veikkolainen, K. Komminaho, T. Skrzynik, Sakari Väkevä, A. Heinonen","doi":"10.17741/bgsf/94.2.004","DOIUrl":"https://doi.org/10.17741/bgsf/94.2.004","url":null,"abstract":"We present results from a deep seismic sounding (DSS) experiment carried out along the southern coast of Finland in summer 2015. Data used in the survey derived from industrial blasts recorded by temporary project stations and permanent network stations. The western 220 km part of the 450 km long Southern Finland Coastal (SOFIC) profile runs along the Uusimaa belt (UB) in the 1.7–1.9 Ga Southern Finland subprovince (SFS) of the Svecofennian domain, while the 170 km part in the east crosses the 1.62–1.65 Ga Wiborg rapakivi batholith (WRB). The farthest 60 km cross a geologically diverse area consisting of supracrustal rocks and granitoids of the Saimaa area (SA), an eastern extension of the SFS. Our results show that the Moho boundary depth varies significantly, from ca. 52–54 km below UB to 40–45 km below WRB. All three crustal layers (upper, middle, and lower) have their maximum depth in the contact zone between UB and the WRB. Below WRB, a lower crust with Vp ~6.7–6.9 km/s is observed. High velocity lower crust was observed below UB (Vp ~7.2 km/s) and possibly below SA (Vp ~7.35 km/s). The modelling was based on ray tracing, using the extrapolation of seismic wave arrival times with the help of travel times predicted from a one-dimensional velocity model. The resulting two-dimensional velocity model partly relies on data from the intersecting DSS profiles and supports previous observations of the lithospheric structure of southeastern Fennoscandia.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42270594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The E-MORB type Haveri basalt differs from the volcanic arc type rocks in the Tampere belt showing no subduction signature. It is considered to have formed in a marginal basin prior to the volcanic arc. We present here zircon U-Pb dating on two samples. The basalt and the felsic dyke yielded 207Pb/206Pb ages of 1902 ± 5 Ma and 1891 ± 2 Ma, respectively, interpreted as crystallisation ages. The basalt also contains older 1.98 Ga grains while the felsic dyke contains older 1.92 Ga, 1.94 Ga, 1.98 Ga and 2.0 Ga grains, which are inferred as inherited. The age dating of E-MORB type basalts can be used to identify the extensional episodes of the accretionary Svecofennian orogeny.
{"title":"Zircon dating of the basalt and felsic dyke in Haveri, SW Finland","authors":"Jaakko Kara, M. Väisänen, H. O'Brien","doi":"10.17741/bgsf/94.2.001","DOIUrl":"https://doi.org/10.17741/bgsf/94.2.001","url":null,"abstract":"The E-MORB type Haveri basalt differs from the volcanic arc type rocks in the Tampere belt showing no subduction signature. It is considered to have formed in a marginal basin prior to the volcanic arc. We present here zircon U-Pb dating on two samples. The basalt and the felsic dyke yielded 207Pb/206Pb ages of 1902 ± 5 Ma and 1891 ± 2 Ma, respectively, interpreted as crystallisation ages. The basalt also contains older 1.98 Ga grains while the felsic dyke contains older 1.92 Ga, 1.94 Ga, 1.98 Ga and 2.0 Ga grains, which are inferred as inherited. The age dating of E-MORB type basalts can be used to identify the extensional episodes of the accretionary Svecofennian orogeny.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49092445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Heilimo, Sini Halonen, S. Mertanen, Sami Niemi, Perttu Mikkola
The Paleoproterozoic Svecofennian Central Finland Granitoid Complex (CFGC) has been regarded as an area of low mineralisation potential. The Hiekkapohja area, 20km north-east of the town of Jyväskylä, host a concentration of variable metalliferous showings. Samples from mineralised boulders and outcrops display variable combinations of anomalously high concentrations of Cu, Mo, Zn, Pb, W, Pb, Ag, As, and Au. The area is composed mainly of peraluminous and ferroan granitoids. The dominant porphyritic Hiekkapohja granodiorite (~1.88 Ga) is cross-cut by the equigranular Soimavuori granite of similar age. The porphyritic Lehesvuori granite on the western side of the study area represents marginally older (~1.89 Ga) magmatism. The paragenetic sequence of the ore minerals shows that the Hiekkapohja area has been affected by at least two separate stages of hydrothermal activity. The first mineralisation stage was widespread, crystallising typically chalcopyrite, pyrrhotite, sphalerite, galena, arsenopyrite, magnetite and Ag-bearing minerals. After the first stage, a low temperature oxidising phase formed hematite and marcasite. The second mineralisation stage enclosed low temperature minerals, such as marcasite and native Ag and Ag-minerals, as inclusions inside chalcopyrite, pyrite, pyrrhotite, sphalerite, and arsenopyrite. The mineralised samples typically display signs of K-metasomatism and less commonly signs of propylitic alteration. During the second mineralisation stage the fluid flow was controlled by the dominant 120°–135° trending shear zones. Both the hydrothermal activity and the regional geology indicate that porphyry type ore forming processes have occurred in the Hiekkapohja area. Paleoproterozoic resetting of the remanent magnetisation is further evidence for the role of the hydrothermal system.
{"title":"Hiekkapohja hydrothermal system – ore mineral, lithogeochemical and paleomagnetic evidence from the Paleoproterozoic Central Finland Granitoid Complex","authors":"E. Heilimo, Sini Halonen, S. Mertanen, Sami Niemi, Perttu Mikkola","doi":"10.17741/bgsf/94.2.003","DOIUrl":"https://doi.org/10.17741/bgsf/94.2.003","url":null,"abstract":"The Paleoproterozoic Svecofennian Central Finland Granitoid Complex (CFGC) has been regarded as an area of low mineralisation potential. The Hiekkapohja area, 20km north-east of the town of Jyväskylä, host a concentration of variable metalliferous showings. Samples from mineralised boulders and outcrops display variable combinations of anomalously high concentrations of Cu, Mo, Zn, Pb, W, Pb, Ag, As, and Au. The area is composed mainly of peraluminous and ferroan granitoids. The dominant porphyritic Hiekkapohja granodiorite (~1.88 Ga) is cross-cut by the equigranular Soimavuori granite of similar age. The porphyritic Lehesvuori granite on the western side of the study area represents marginally older (~1.89 Ga) magmatism. The paragenetic sequence of the ore minerals shows that the Hiekkapohja area has been affected by at least two separate stages of hydrothermal activity. The first mineralisation stage was widespread, crystallising typically chalcopyrite, pyrrhotite, sphalerite, galena, arsenopyrite, magnetite and Ag-bearing minerals. After the first stage, a low temperature oxidising phase formed hematite and marcasite. The second mineralisation stage enclosed low temperature minerals, such as marcasite and native Ag and Ag-minerals, as inclusions inside chalcopyrite, pyrite, pyrrhotite, sphalerite, and arsenopyrite. The mineralised samples typically display signs of K-metasomatism and less commonly signs of propylitic alteration. During the second mineralisation stage the fluid flow was controlled by the dominant 120°–135° trending shear zones. Both the hydrothermal activity and the regional geology indicate that porphyry type ore forming processes have occurred in the Hiekkapohja area. Paleoproterozoic resetting of the remanent magnetisation is further evidence for the role of the hydrothermal system.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49601509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In migmatitic environments the behaviour of the system is controlled by the generation and amount of the anatectic melt. Accordingly, migmatites typically show a genetic linkage between the tectonic deformation and melt migration. We investigated this relationship in Olkiluoto (SW Finland) and identified four phases of ductile deformation, which are distinguished by the multiple folding phases, ductile shear events and cross-cutting features associated with pegmatitic leucosomes and/or a specific type of diatexitic migmatite with feldspar megacrysts. U–Pb LA-MC-ICPMS data on zircon cores and rims from migmatites and cross-cutting pegmatites indicate two distinct metamorphic events associated with melt generation and migration at 1.87–1.84 Ga and 1.82–1.78 Ga. These two migmatitic events suggest that the orogenic evolution of the area was long-lasting and characterized by slow cooling. The structural data and the age constraints presented in this paper support the idea of similar tectonic evolution and metamorphic environment in SW Finland and central E Sweden.
{"title":"Palaeoproterozoic structural evolution of polyphase migmatites in Olkiluoto, SW Finland","authors":"Jon Engström, A. Kärki, S. Paulamäki, I. Mänttäri","doi":"10.17741/bgsf/94.2.002","DOIUrl":"https://doi.org/10.17741/bgsf/94.2.002","url":null,"abstract":"In migmatitic environments the behaviour of the system is controlled by the generation and amount of the anatectic melt. Accordingly, migmatites typically show a genetic linkage between the tectonic deformation and melt migration. We investigated this relationship in Olkiluoto (SW Finland) and identified four phases of ductile deformation, which are distinguished by the multiple folding phases, ductile shear events and cross-cutting features associated with pegmatitic leucosomes and/or a specific type of diatexitic migmatite with feldspar megacrysts. U–Pb LA-MC-ICPMS data on zircon cores and rims from migmatites and cross-cutting pegmatites indicate two distinct metamorphic events associated with melt generation and migration at 1.87–1.84 Ga and 1.82–1.78 Ga. These two migmatitic events suggest that the orogenic evolution of the area was long-lasting and characterized by slow cooling. The structural data and the age constraints presented in this paper support the idea of similar tectonic evolution and metamorphic environment in SW Finland and central E Sweden.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44423038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Mollehuara-Canales, N. Afonin, E. Kozlovskaya, J. Lunkka, D. Pedretti
We applied active-source seismic method for the interpretation of elastic parameters in tailings facilities which is essential for evaluating stability and seismic response. The methodology uses different analysis methods on the same dataset, i.e., conventional seismic refraction (SR) to determine compressional-wave velocity (Vp) and multichannel analysis of surface wave (MASW) to estimate shear-wave velocity (Vs). Seismic velocities in conjunction with tailings physics approach revealed interpretable data in terms of elastic parameters and hydrogeological conditions. The results determined the empirical linear relationships between Vp and Vs that are particular to an unconsolidated media such as tailings and showed that variability of hydrogeological conditions influences the elastic seismic response (Vp and Vs) and the elastic parameters. The analysis of the elastic parameters identified the state condition of the tailings at the time of the survey. The Bulk modulus K that relates the change in hydrostatic stress to the volumetric strain was predominant between 1.0−2.0 GPa. The Young’s modulus E in the tailings media was in the low range of 0.15−0.23 GPa. Poisson’s ratio values in all sections were in the upper limit in the range of 0.37−0.49, meaning that the tailings media is highly susceptible to transverse deformation under axial compression.
{"title":"Leveraging active-source seismic data in mining tailings: Refraction and MASW analysis, elastic parameters, and hydrogeological conditions","authors":"R. Mollehuara-Canales, N. Afonin, E. Kozlovskaya, J. Lunkka, D. Pedretti","doi":"10.17741/bgsf/93.2.002","DOIUrl":"https://doi.org/10.17741/bgsf/93.2.002","url":null,"abstract":"We applied active-source seismic method for the interpretation of elastic parameters in tailings facilities which is essential for evaluating stability and seismic response. The methodology uses different analysis methods on the same dataset, i.e., conventional seismic refraction (SR) to determine compressional-wave velocity (Vp) and multichannel analysis of surface wave (MASW) to estimate shear-wave velocity (Vs). Seismic velocities in conjunction with tailings physics approach revealed interpretable data in terms of elastic parameters and hydrogeological conditions. The results determined the empirical linear relationships between Vp and Vs that are particular to an unconsolidated media such as tailings and showed that variability of hydrogeological conditions influences the elastic seismic response (Vp and Vs) and the elastic parameters. The analysis of the elastic parameters identified the state condition of the tailings at the time of the survey. The Bulk modulus K that relates the change in hydrostatic stress to the volumetric strain was predominant between 1.0−2.0 GPa. The Young’s modulus E in the tailings media was in the low range of 0.15−0.23 GPa. Poisson’s ratio values in all sections were in the upper limit in the range of 0.37−0.49, meaning that the tailings media is highly susceptible to transverse deformation under axial compression.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49077994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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