Bulletin of the Geological Society of Finland最新文献

{"title":"The inselberg landscape in Finnish Lapland: a morphological study based on the LiDAR data interpretation","authors":"K. Nenonen, P. Johansson, O. Sallasmaa, P. Sarala, J. Palmu","doi":"10.17741/BGSF/90.2.008","DOIUrl":"https://doi.org/10.17741/BGSF/90.2.008","url":null,"abstract":"An advanced method to study geomorphology of the well-known inselberg landscape in Finnish Lapland is introduced. Conventionally topographical maps and altitude reference produced from stereographic aerial photographs has been used. Now the LiDAR data has opened a new way to study geomorphology and terrain in detail. We applied the new methods in eastern Finnish Lapland from where seven inselbergs have been identified and analysed. With an accurate elevation data and images we could identify the detailed morphology in the inselbergs and examine the processes that actively alter the terrain. LiDAR data opened a view to the preglacial history and processes. Some preliminary estimations of the rate and amount of preglacial erosion could be made. It seems that erosion rate may have been in order of 2–10 m/Myr in Lapland based on existing datings and stratigraphic observations. Weathering and erosion history in Lapland is long as the kaolinite clays of Late Cenozoic, Mesozoic or even Mesoproterozoic in age are found in the weathered bedrock. Although all disconformities older than the Mesozoic era have probably been eroded to an unidentifiable extent, there is good reason to suppose that the main characteristics of the relief, including inselbergs, originated as early as the Late Cretaceous or at least in","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48837635","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":"Glaciotectonically deformed glaciofluvial sediments with ruptured pebbles (the Koczery study site, E Poland)","authors":"B. Woronko, Szymon Belzyt, Ł. Bujak, M. Pisarska‐Jamroży","doi":"10.17741/BGSF/90.2.001","DOIUrl":"https://doi.org/10.17741/BGSF/90.2.001","url":null,"abstract":"Significant quantities of ruptured pebbles are found in glaciotectonically deformed glaciofluvial sediments of the Saalian glaciation (MIS 6) at the Koczery site (E Poland). To identify the responsible mechanisms for the pebble-rupture activity, structural, petrographic, roundness and shape analyses were done. Additionally, till fabric of overlying glacial diamicton was analysed and compared to the other outcomes. The origin of fractures in ruptured pebbles of glaciofluvial sediments is directly linked to compressive stress caused by glaciotectonic processes because of 1) ruptured pebbles occur mainly in glaciotectonically deformed sediments (a quarter of all pebbles is fractured); 2) ruptured pebbles almost always occur one-by-one primarily in gravelly lithofacies; 3) fractures occur in pebbles derived from all petrographic groups; 4) fracture occurrence is independent of pebbles size, shape and roundness; 5) fractures mostly occur parallel to each other (along long ‘a’ or short ‘c’ axis of pebbles) and parallel to the bedding of lithofacies; and 6) in most cases broken fragments of ruptured pebbles survived in the host sediment indicating that the observed damage occurred in situ. This novel study of ruptured pebbles found in glacigenic environments sheds new light on the dynamics of glaciotectonic processes, and may be useful in the characterization of palaeostresses that occur during glaciotectonic deformations.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47697568","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":"The SIS limits and related proglacial events in the Severnaya Dvina basin, northwestern Russia: review and new data","authors":"N. Zaretskaya, A. Panin, N. Karpukhina","doi":"10.17741/BGSF/90.2.012","DOIUrl":"https://doi.org/10.17741/BGSF/90.2.012","url":null,"abstract":"Two underlying problems of the Late Quaternary history of the Scandinavian Ice Sheet (SIS) are reviewed in the paper: the position of the southeastern SIS boundary at the Late Glacial Maximum (LGM), which is still widely “migrating” depending on authors’ concepts, and the formation of associated proglacial lakes (i.e. their dimensions, drainage and chronology) in the valleys of Severnaya Dvina River basin. The position of maximum ice limit in the northwest of the Russian Plain remains debatable and is the least reliable compared to the other SIS sectors. Most of the recent reconstructions concerning ice-dammed lakes (water overflows, restructuring of river valleys etc.) exploited the geological survey results of mid-20th century: since then no geological studies have been conducted of the proposed spillways, their filling sediments and age using the modern sedimentological and geochronological techniques. As a result, the majority of the above-mentioned reconstructions have to be considered hypothetical. Here we present new results on two valley sites that allow to suggest that: 1) the SIS did not advance through the lower and middle Vychegda valley at LGM as suggested in some recent publications; 2) the LGM glacier-dammed lake had a very limited extension in the Severnaya Dvina valley and did not exceed to the Vychegda River mouth.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42638823","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":"Some features of deformation structures in an esker on the southern margin of the Fennoscandian shield","authors":"A. Poleshchuk, D. Zykov, S. Shvarev","doi":"10.17741/BGSF/90.2.011","DOIUrl":"https://doi.org/10.17741/BGSF/90.2.011","url":null,"abstract":"As a result of melting of the last ice sheet in the southeastern edge of the Fennoscandian shield, ridge structures called eskers were formed. One of these eskers is the subject of our study. We have identified both typical non-deformed sedimentary layers and specific intrusive mixture of sand and silt in the esker. The sand and silt were deformed with formation of recumbent and overturned folds, which indicate that they have experienced displacement in a ductile (wet) state. The formation of similar dislocations (diapir folds or glacial intrusion structures) can occur as a result of either dead ice melting or liquefaction during earthquakes.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42003995","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":"Orientation of gravels and soft-sediment clasts in subaqueous debrites – implications for palaeodirection reconstruction: case study from Puck Bay, northern Poland","authors":"P. Woźniak, M. Pisarska‐Jamroży, Ł. Elwirski","doi":"10.17741/bgsf/90.2.002","DOIUrl":"https://doi.org/10.17741/bgsf/90.2.002","url":null,"abstract":"Subaqueous debrites on a fan were recognized at Rzucewo (N Poland). Analysis of debrite fabric enabled debris-flow palaeodirections to be traced on the fan. The long axis azimuth and dip direction of lithic clasts (gravels) as well as soft-sediment clasts (SSC) were measured in the debrites. The results obtained indicate a palaeotransport direction to NNW, similar to the palaeocurrents interpreted from the asymmetrical ripples. However, detailed measurements of both gravels and SSC orientation show variability of palaeoflow directions between NW and NE sectors. In the proximal part of the fan, gravels indicate variable dip directions and dip angles, and a mostly scattered distribution of a-axis orientation. In the medial and distal parts of the fan, clasts are better ordered and usually their a-axes are oriented upslope or transverse to the palaeoslope inclination direction. Probably during the decelerating and halting of debris flows, the compression processes induced clast rotation and a change of inclination. In the distal part of the fan, debrites reveal a distinct variability of palaeoflow directions caused by flattened topography in which debris-flow lobes split and spread freely in different directions. Finally, we conclude that the individual sets of clast fabric usually indicate only local debris-flow directions.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48245197","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":"Characterization and origin of dunitic rocks in the Ni-Cu-(PGE) sulfide ore-bearing Kevitsa intrusion, northern Finland : whole-rock and mineral chemical constraints","authors":"K. Luolavirta, E. Hanski, W. Maier, F. Santaguida","doi":"10.17741/BGSF/90.1.001","DOIUrl":"https://doi.org/10.17741/BGSF/90.1.001","url":null,"abstract":"The ca. 2.06 Ga Kevitsa intrusion is one of the ore-bearing mafic-ultramafic igneous bodies in the Central Lapland greenstone belt. A large disseminated Ni-Cu-(PGE) sulfide ore deposit is hosted by olivine-pyroxene cumulates in the lower ultramafic part of the intrusion, indicating involvement of a multiply saturated magma in the ore formation. There are also various dunitic rocks, which occur as numerous inclusions within the Kevitsa intrusion, most commonly in the economic resource area. On textural basis, two distinct types of inclusions are recognized: i) cumulate-textured (Kevitsa Dunite) and ii) recrystallized ultramafic inclusions. In addition, there also exists a separate dunitic body (Central Dunite) with a suface area of 0.6 x 1.0 km, cropping out in the central part of the intrusion. The Central Dunite and Kevitsa Dunite are similar olivine-chromite cumulates and with comparable whole-rock and mineral compositions, suggesting that they are cogenetic. A magmatic, rather than replacement origin for the dunitic cumulates is evidenced by their systematic mineral compositional trends consistent with magmatic fractionation. Wholerock major and trace element and mineral compositional data of the dunitic cumulates and Kevitsa olivine pyroxenites fall on the same linear trends and record similar REE characteristics indicating a genetic link between these two. The parental magmas for the dunitic cumulates were probably picritic and related to the picritic and basaltic volcanic rocks in the area. The high Fo content of olivine (up to ~89 mol.%) is consistent with a highMg parental melt. The recrystallized ultramafic inclusions are fine-grained and show a granoblastic/interlobate textures indicative for thermal textural readjustment. Two subgroups are identified: Group 1 shows a chemical affinity towards the dunitic cumulates and are interpreted as their recrystallized clasts. The Group 2 inclusions are compositionally comparable to the ~2.06 Ga komatiitic volcanic rocks in the area and are considered as dehydrated metavolcanic xenoliths. A decrease in the flow rate of the Kevitsa magmas due to entrapment of a high number of inclusions is proposed as a mechanism to promote settling of sulfides, contributing to the formation of the Ni-Cu-(PGE) ore.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"90 1","pages":"5-32"},"PeriodicalIF":0.7,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47254536","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":"Valorization of Finnish mining tailings for use in the ceramics industry","authors":"Soili Solismaa, A. Ismailov, Marjaana Karhu, Harisankar Sreenivasan, M. Lehtonen, P. Kinnunen, M. Illikainen, M. Räisänen","doi":"10.17741/BGSF/90.1.002","DOIUrl":"https://doi.org/10.17741/BGSF/90.1.002","url":null,"abstract":"The present study valorized Finnish mining tailings waste to identify opportunities for the use of ceramics technologies. On the basis of their mineralogical and chemical contents, the five selected tailings wastes represented felsic mining tailings (FMT) rich in quartz and alkali feldspars, mining tailings dominated by Mgand Fe-bearing minerals (MgFeMT), and mining tailings rich in carbonate minerals (CMT). Preliminary pilot studies indicated that the FMT materials are potential secondary raw materials for mullite-type ceramics. An Al additive was needed, since the Al2O3 content of the studied tailings was too low for mullitization. In addition, carbonate-bearing tailings with Ca silicates can be applicable for chemically bonded phosphate ceramic (CBPC) synthesis. Based on a literature review, FMT are viable source materials for the production of geopolymers, but a high initial Si:Al ratio (in quartz-rich FMT) may lead to partial geopolymerization. Preliminary results from the geopolymerization of pre-heated phlogopite mica mixed with metakaolin gave promising findings, with the formation of a geopolymer having good compressive strength. The findings support the viability of MgFeMT materials rich in phlogopite mica for the production of alkali-activated ceramics.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49116377","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":"Epigenetic gold occurrence in a Paleoproterozoic meta-evaporitic sequence in the Rompas-Rajapalot Au system, Peräpohja belt, northern Finland","authors":"J. Ranta, F. Molnár, E. Hanski, N. Cook","doi":"10.17741/BGSF/90.1.004","DOIUrl":"https://doi.org/10.17741/BGSF/90.1.004","url":null,"abstract":"The Rompas-Rajapalot gold prospect is located in the northern part of the Paleoproterozoic Peräpohja belt. It covers an area of at least 10 x 10 km and comprises various styles of gold mineralization ranging from localized high-grade Au pockets in uraniniteand pyrobitumen-bearing calcsilicate-carbonate-quartz veins in mafic metavolcanic rocks (Rompas area) to disseminated gold grains in Fe-Mg-rich metasediments and quartz-tourmaline-sulfide-native gold veins (Palokas area). This study deals with the petrography and mineral chemistry of the gold mineralization at Palokas, which occurs in the eastern part of the Rompas-Rajapalot prospect. Major and trace element data and fluid inclusion characteristics of tourmaline are used to evaluate the origin and the pressure-temperature-fluid composition parameters of hydrothermal fluids. Whole-rock geochemical analyses are utilized to evaluate the nature of the protolith of the host rocks. Gold occurs in a native form in at least two different textural settings: 1) single, relatively coarse grains disseminated among the rock-forming silicates in cordierite-orthoamphibole rocks and 2) smaller grains occurring in fractures of tourmaline in quartz-sulfide-tourmaline breccias and in fractures of chloritized cordierite-orthoamphibole rocks adjacent to the tourmaline-rich breccias. Fracture-related gold is associated with Bi-Se-S-bearing tellurides, native Bi, molybdenite, chalcopyrite, and pyrrhotite. Coarser-grained disseminated gold were not found to be clearly associated with sulfides nor any fractures. Statistical correlations show that the Au concentration correlates strongly with Te, Cu, Co, Se, Bi, Mo, and Ag (ρ = 0.730–0.619) whereas Au correlates moderately with As, Fe, W (ρ = 0.523–0.511) and to a lesser extent with U, Pb, and Ni (ρ = 0.492–0.407). Gold has the strongest negative correlations with Sr and Ca. The chondrite-normalized REE patterns of tourmaline from the Au-mineralized rocks (both vein type and host-rock tourmaline) and the lateto post-orogenic granite partly overlap and show similar LREE-enriched trends, with the enrichment being lower in tourmaline from the granite. Fluid inclusion studies from tourmaline in gold-bearing Bulletin of the Geological Society of Finland, Vol. 90, 2018, pp 69–108, https://doi.org/10.17741/bgsf/90.1.004 70 J.-P. Ranta, F. Molnár, E. Hanski and N. Cook quartz-tourmaline-sulfide veins indicate that the veins were formed from H2O-Na2O-CO2CH4-(H2S) fluids in a boiling system under pressure conditions ranging from lithostatic to hydrostatic, with the depth being ~5 km and the temperature ~300°C. The properties of the ore-forming fluids support the genetic link between the lateto post-orogenic granitoid magmatism at ~1.78 Ga and the formation of the fracture-hosted gold mineralization, suggested based on earlier studies (including Re-Os-molybdenite age and boron isotope data from tourmaline). Based on the whole-rock geochemistry, it is highly plausible that the cord","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47763197","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":"The petrology and genesis of the Paleoproterozoic mafic intrusion-hosted Co-Cu-Ni deposit at Hietakero, NW Finnish Lapland","authors":"J. Konnunaho, E. Hanski, T. Karinen, Y. Lahaye, H. Makkonen","doi":"10.17741/BGSF/90.1.005","DOIUrl":"https://doi.org/10.17741/BGSF/90.1.005","url":null,"abstract":"Cobalt is a highly sought-after metal due to its economic importance in many high-tech applications. It is mainly obtained from sedimentary-hosted Cu-Co deposits and magmatic Ni-Cu deposits as a by-product. We describe a recently discovered Co-enriched Cu-Ni deposit hosted by the Hietakero mafic intrusion in north-western Finnish Lapland. The intrusion contains gabbroic to pyroxenitic cumulates and was emplaced into a supracrustal strata composed mainly of mafic volcanic rocks, sulfur-bearing graphite schists and felsic volcanic interlayers. Hybrid rocks provide clear evidence for interaction of mafic magma with its country rocks. All these rocks have undergone intensive post-magmatic hydrothermal alteration by influx of H 2 O-, CO 2 - and Cl-bearing saline fluids, forming strongly scapolitized (±albitized) rocks and resulting in re-mobilization of sulfides and their metals. The Hietakero deposit is associated with pyroxenitic cumulates and hybrid rocks, with the sulfides (pyrrhotite, cobaltian pentlandite, chalcopyrite and pyrite) occurring as patches, brecciated to net-textured and Instead, an external source of cobalt is needed, which is also consistent with the high Zn, Pb and Mo contents of the mineralized rocks. Based on sulfur isotope compositions, the associated black shales were not the primary source of sulfur, but sulfur was rather derived from a so far unrecognized, potentially Co-bearing contaminant with close to mantle-like δ 34 S. Our study reveals a new Co-Cu-Ni deposit type related to the widespread Paleoproterozoic mafic magmatism in Lapland.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41493962","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":"2.5D open source modeling of rock aggregate resources in the Helsinki metropolitan area","authors":"Samppa Mäkelä","doi":"10.17741/BGSF/90.1.003","DOIUrl":"https://doi.org/10.17741/BGSF/90.1.003","url":null,"abstract":"The objective of this study is to develop a method of appraising rock aggregate resources, using open data and open source tools. The availability of aggregates in Finland is mostly determined by competing land use and restrictions on extraction. Therefore, it is important to determine the extent of available resources, especially near areas of high","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2018-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45316721","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}