B. Woronko, Szymon Belzyt, Ł. Bujak, M. Pisarska‐Jamroży
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.
{"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":null,"pages":null},"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}
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.
{"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":null,"pages":null},"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}
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.
{"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":null,"pages":null},"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}
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.
约2.06 Ga Kevitsa侵入体是拉普兰中部绿岩带的含矿基性-超镁铁性火成岩之一。岩体下部超基性橄榄石-辉石堆积为大型浸染型镍铜(PGE)硫化物矿床，表明成矿过程中有多次饱和岩浆参与。还有各种双质岩，它们以大量包裹体的形式出现在Kevitsa侵入体中，最常见于经济资源区。在结构上，可识别出两种不同类型的包裹体:1)堆积织构(Kevitsa Dunite)和2)再结晶超镁铁质包裹体。此外，在侵入体的中部还存在一个单独的泥质体(中央泥质体)，其表面积为0.6 x 1.0 km。中央灰岩和凯维特沙灰岩是相似的橄榄铬铁矿堆积，具有相似的全岩和矿物组成，表明它们是同成的。与岩浆分馏相一致的系统矿物组成趋势证明了双质堆积的岩浆成因，而不是替代成因。双质岩和凯维特萨橄榄辉石岩的主微量元素和矿物组成数据均呈相同的线性趋势，稀土元素特征相似，表明两者之间存在成因联系。泥质堆积物的母岩浆可能为苦橄质，与该区苦橄质和玄武质火山岩有关。橄榄石的高Fo含量(高达~89 mol.%)与高mg母熔体相一致。再结晶超镁铁质包裹体晶粒细，呈花岗质/片间织构，表明热织构调整。鉴定出两个亚群:第1群显示出与二元堆积的化学亲和力，并被解释为它们的再结晶碎屑。第2组包裹体的成分与该区~2.06 Ga科马马岩质火山岩相当，属于脱水变质火山包体。大量包裹体的包裹使Kevitsa岩浆流速降低，从而促进了硫化物的沉降，促进了镍铜矿的形成。
{"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":null,"pages":null},"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}
Soili Solismaa, A. Ismailov, Marjaana Karhu, Harisankar Sreenivasan, M. Lehtonen, P. Kinnunen, M. Illikainen, M. Räisänen
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.
{"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":null,"pages":null},"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}
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
Rompas-Rajapalot金矿床位于古元古代Peräpohja带的北部。它的面积至少为10 x 10 km，包括各种类型的金矿化，从含铀岩中的局部高品位Au囊和镁铁质变火山岩中的含焦沥青钙硅酸盐碳酸盐石英脉（Rompas地区）到富含铁-镁的变质沉积物和石英-电气石-硫化物原生金矿（Palokas地区）中的浸染状金粒。本研究涉及Palokas金矿化的岩石学和矿物化学，该金矿化发生在Rompas-Rajapalot勘探区的东部。利用电气石的主、微量元素数据和流体包裹体特征，对热液的成因和压力-温度-流体组成参数进行了评价。利用全岩地球化学分析来评价寄主岩石原岩的性质。金以天然形式存在于至少两种不同的结构环境中：1）散布在堇青石-正角闪石岩石中的岩石形成硅酸盐中的单一、相对较粗的颗粒，以及2）石英-硫化物-电气石角砾岩中电气石裂缝和与富含电气石的角砾岩相邻的氯化堇青石-斜角闪石岩石裂缝中出现的较小颗粒。与断裂有关的金与含Bi-Se-S的碲化物、原生Bi、辉钼矿、黄铜矿和磁黄铁矿有关。未发现粗粒浸染状金与硫化物或任何裂缝明显相关。统计相关性表明，Au浓度与Te、Cu、Co、Se、Bi、Mo和Ag密切相关（ρ=0.730–0.619），而Au与As、Fe、W适度相关（ρ=0.523–0.511），与U、Pb和Ni的相关性较小（ρ=0.492–0.407）。金与Sr和Ca的负相关性最强。Au矿化岩石电气石（包括脉型和主岩电气石）和晚造山后花岗岩的球粒陨石归一化REE模式部分重叠，并显示出相似的LREE富集趋势，其中花岗岩电气石的富集度较低。《芬兰地质学会含金公报》2018年第90卷第69–108页中电气石的流体包裹体研究，https://doi.org/10.17741/bgsf/90.1.00470 J.-P.Ranta、F.Molnár、E.Hanski和N.Cook石英-电气石硫化物矿脉表明，这些矿脉是由沸腾系统中的H2O-Na2O-CO2CH4-（H2S）流体在从岩石静力到流体静力的压力条件下形成的，深度约5km，温度约300°C。根据早期研究（包括电气石的Re-Os辉钼矿年龄和硼同位素数据），成矿流体的性质支持了约1.78 Ga的晚造山-后造山花岗岩类岩浆作用与断裂金矿化形成之间的成因联系。根据全岩地球化学，堇青石-正长角闪岩和层间钙硅绿柱石是全盆地湖相序列的一部分，至少部分是蒸发岩序列。堇青石-正角闪岩的原岩很可能是一个湖缘沉积堆，含有丰富的富镁粘土。
{"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":null,"pages":null},"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}
J. Konnunaho, E. Hanski, T. Karinen, Y. Lahaye, H. Makkonen
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.
{"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":null,"pages":null},"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}
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
{"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":null,"pages":null},"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}
LiDAR-based (Light Detection And Ranging) 2 m-grid digital elevation models (DEM) are exceptional remote sensing data in geosciences in many aspects: they can be used to constrain terrain features in greater detail than ever before (Johnson et al., 2015), allow extraction of new geomorphological features and relationships (Mäkinen et al., 2017), provide a possibility of acquiring 3D information of the terrain, and nowadays cover extensive areas in Finland (ca. 90%), and elsewhere in the Fennoscandian Shield. LiDAR DEMs open up new ways of investigating and modelling of geological processes and geomorphological characteristics, and thus provide significant potential for advancing theories in geosciences. In Scandinavia, high-resolution LiDAR imagery has so far been employed to study and map a wide range of glacial geomorphology and postglacial terrain features. These include research on issues such as ribbed (Rogen) and hummock moraines and their tracks and corridors (Möller and Dowling, 2015; Peterson et al., 2017), ice streaming (Greenwood et al., 2015), De Geer moraines (Bouvier et al., 2015; Ojala et al., 2015; Ojala 2016), subglacial meltwater systems (Sarala et al., 2015), beach ridges, cliffs and shore terraces (Ojala et al., 2013), fluvial terraces, floods plains and lateral meltwater channels (Eilertsen et al., 2015), Bulletin of the Geological Society of Finland, Vol. 89, 2017, pp 61–63, https://doi.org/10.17741/bgsf/89.2.ed
基于激光雷达(lidar)的2米网格数字高程模型(DEM)在地球科学的许多方面都是特殊的遥感数据:它们可用于比以往更详细地约束地形特征(Johnson et al.， 2015)，允许提取新的地貌特征和关系(Mäkinen et al.， 2017)，提供获取地形3D信息的可能性，如今覆盖了芬兰(约90%)的广大地区，以及芬诺斯坎地盾的其他地方。激光雷达dem开辟了研究和模拟地质过程和地貌特征的新途径，从而为推进地球科学理论提供了巨大的潜力。在斯堪的纳维亚半岛，高分辨率激光雷达图像迄今已被用于研究和绘制广泛的冰川地貌和冰川后地形特征。其中包括对肋状(罗根)和丘状冰碛及其轨迹和走廊等问题的研究(Möller和Dowling, 2015;Peterson等人，2017)，冰流(Greenwood等人，2015)，De Geer moraines (Bouvier等人，2015;Ojala et al.， 2015;Ojala 2016)，冰下融水系统(Sarala等人，2015)，海滩山脊，悬崖和海岸阶地(Ojala等人，2013)，河流阶地，洪泛平原和侧向融水通道(Eilertsen等人，2015)，芬兰地质学会公报，2017年第89卷，61-63页，https://doi.org/10.17741/bgsf/89.2.ed
{"title":"Editorial: LiDAR – rapid developments in remote sensing of geological features","authors":"A. Ojala, P. Sarala","doi":"10.17741/BGSF/89.2.ED","DOIUrl":"https://doi.org/10.17741/BGSF/89.2.ED","url":null,"abstract":"LiDAR-based (Light Detection And Ranging) 2 m-grid digital elevation models (DEM) are exceptional remote sensing data in geosciences in many aspects: they can be used to constrain terrain features in greater detail than ever before (Johnson et al., 2015), allow extraction of new geomorphological features and relationships (Mäkinen et al., 2017), provide a possibility of acquiring 3D information of the terrain, and nowadays cover extensive areas in Finland (ca. 90%), and elsewhere in the Fennoscandian Shield. LiDAR DEMs open up new ways of investigating and modelling of geological processes and geomorphological characteristics, and thus provide significant potential for advancing theories in geosciences. In Scandinavia, high-resolution LiDAR imagery has so far been employed to study and map a wide range of glacial geomorphology and postglacial terrain features. These include research on issues such as ribbed (Rogen) and hummock moraines and their tracks and corridors (Möller and Dowling, 2015; Peterson et al., 2017), ice streaming (Greenwood et al., 2015), De Geer moraines (Bouvier et al., 2015; Ojala et al., 2015; Ojala 2016), subglacial meltwater systems (Sarala et al., 2015), beach ridges, cliffs and shore terraces (Ojala et al., 2013), fluvial terraces, floods plains and lateral meltwater channels (Eilertsen et al., 2015), Bulletin of the Geological Society of Finland, Vol. 89, 2017, pp 61–63, https://doi.org/10.17741/bgsf/89.2.ed","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44270504","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 SIS (Scandinavian Ice Sheet) became divided into several active, semi-independent ice lobes during the last deglaciation ca 13 000–10 000 years ago. The largest of them, the North Karelian/Oulu Ice Lobe (NKIL/OIL), covered vast areas in central Finland and in northwest Russian Karelia. This paper studies the behaviour and subglacial conditions of the NKIL/OIL with the inversion modelling method. The method is based on the identification and interpretation of mapped glacigenic streamlined lineations, formed during active flow stages of the NKIL/OIL. DEM and LiDAR data on lineations was obtained from seven subsets in different zones of the NKIL/OIL. Results indicate that the NKIL/OIL dynamics were strongly affected by pre-existing Quaternary sediment thickness, bedrock lithology, structures and topography. Due to these factors, the NKIL/ OIL operated through several flow corridors and had several retreat and re-advance cycles throughout its life span.
{"title":"Factors affecting the dynamics of the North Karelian/Oulu Ice Lobe, Central Finland, during the last deglaciation – a LiDAR and DEM interpretation of subglacial lineation patterns","authors":"T. Nikarmaa, J. Lunkka, N. Putkinen","doi":"10.17741/BGSF/89.2.003","DOIUrl":"https://doi.org/10.17741/BGSF/89.2.003","url":null,"abstract":"The SIS (Scandinavian Ice Sheet) became divided into several active, semi-independent ice lobes during the last deglaciation ca 13 000–10 000 years ago. The largest of them, the North Karelian/Oulu Ice Lobe (NKIL/OIL), covered vast areas in central Finland and in northwest Russian Karelia. This paper studies the behaviour and subglacial conditions of the NKIL/OIL with the inversion modelling method. The method is based on the identification and interpretation of mapped glacigenic streamlined lineations, formed during active flow stages of the NKIL/OIL. DEM and LiDAR data on lineations was obtained from seven subsets in different zones of the NKIL/OIL. Results indicate that the NKIL/OIL dynamics were strongly affected by pre-existing Quaternary sediment thickness, bedrock lithology, structures and topography. Due to these factors, the NKIL/ OIL operated through several flow corridors and had several retreat and re-advance cycles throughout its life span.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47043685","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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