Bulletin of the Geological Society of Finland最新文献

{"title":"A study of the stable carbon and oxygen isotope composition of recent shells of Mytilidae, especially of oxygen values in relation to temperature","authors":"J. Donner, E. Sonninen, J. Karhu, A. Kotilainen","doi":"10.17741/BGSF/86.2.001","DOIUrl":"https://doi.org/10.17741/BGSF/86.2.001","url":null,"abstract":"Analyses of the stable isotopes 18 O and 13 C were made of modern marine shells of the widely distributed Mytilidae, primarily intertidal species, collected from beaches in Europe and southern Africa, as well as from Australia and Argentina. At sites facing the open sea and where the field data of annual mean sea-surface temperatures have been recorded a comparison could be made between the stable isotope values of the shells and the seawater temperatures. The comparison shows that there is a good negative correlation between the seawater temperatures and the δ 18 O values of the Mytilidae shells. The analyses of a series of samples from the outer layer of the valves from five different sites, at right angles to the annual increments, reflected the seasonal variations of the seawater temperatures. The recorded amplitudes of the isotope temperatures in the shells based on the δ 18 O values were similar to the amplitudes of the recorded sea","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"86 1","pages":"61-70"},"PeriodicalIF":0.7,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630953","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":"Age and isotopic fingerprints of some plutonic rocks in the Wiborg rapakivi granite batholith with special reference to the dark wiborgite of the Ristisaari Island.","authors":"O. T. Rämö, V. Turkki, I. Mänttäri, A. Heinonen, K. Larjamo, Y. Lahaye","doi":"10.17741/BGSF/86.2.002","DOIUrl":"https://doi.org/10.17741/BGSF/86.2.002","url":null,"abstract":"Age and isotopic fingerprints of some plutonic rocks in the Wiborg rapakivi granite batholith with special reference to the dark wiborgite of the Ristisaari Island 1) Department of Geosciences and Geography, Division of Geology, P.O. Box 64, FI-00014 University of Helsinki, Finland 2) Rälssintie 12, FI-47200 Elimäki, Finland 3) Geological Survey of Finland, P.O. Box 96, FI-02150 Espoo, Finland 4) The National SGL Laboratory, c/o Geological Survey of Finland, P.O. Box 96, FI-02150 Espoo, Finland The mid-Proterozoic, locus classicus Wiborg rapakivi granite batholith of southeastern Finland and adjacent Russia comprises a varying, bimodal (silicic-basic) sequence of plutonic, subvolcanic, and volcanic rocks. At the current level of erosion silicic rocks are dominant, the most prominent of which are wiborgites and dark wiborgites (that have been considered to mark the main build-up stage of the batholith) and pyterlites. New observations and optical microscopy data from the dark wiborgite-dominated Ristisaari Island in the southern, off-shore part of the Wiborg batholith show that dark plagioclase megacrysts in dark wiborgite are calcic xenocrysts. They were probably incorporated into wiborgite magma from consanguineous massiftype anorthosite magmas in the course of the evolution of the bimodal magmatic system. Our new ID-TIMS U-Pb zircon age of the Ristisaari Island dark wiborgite, 1627±3 Ma, is the youngest isotopic age so far determined for the plutonic rocks of the Wiborg batholith. This, combined with preexisting U-Pb zircon data, implies a minimum duration of 12 m.y. (1642–1630 Ma) for the emplacement of the plutonic rocks of the batholith. Combined with data on highlevel dike rocks, a window of at least 20 m.y. (1642–1622 Ma) is implied. Furthermore, as the batholith grew, the overall locus of magmatism may have shifted southwards. New whole-rock Nd isotope data on the dark wiborgite of the Ristisaari Island and three further granites of the batholith, as well as Nd (whole-rock) and Sr (whole-rock, plagioclase) isotope data on a spectrolite massif-type anorthosite from the east-central part of the batholith, are also presented. These data suggest that the lithosphere across the Wiborg batholith area in the southeastern part of the Svecofennian orogen may vary slightly in overall mantle separation age.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"86 1","pages":"71-91"},"PeriodicalIF":0.7,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67631097","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":"Svecofennian intra-orogenic gabbroic magmatism: A case study from Turku, southwestern Finland","authors":"J. Nevalainen, M. Väisänen, Y. Lahaye, E. Heilimo, S. Fröjdö","doi":"10.17741/BGSF/86.2.003","DOIUrl":"https://doi.org/10.17741/BGSF/86.2.003","url":null,"abstract":"","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"86 1","pages":"93-112"},"PeriodicalIF":0.7,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630674","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":"Relationships between sanukitoids and crust-derived melts and their implications for the diversity of Neoarchaean granitoids: A case study from Surmansuo and nearby areas, Eastern Finland","authors":"Perttu Mikkola, E. Heilimo, H. Huhma","doi":"10.17741/BGSF/86.1.002","DOIUrl":"https://doi.org/10.17741/BGSF/86.1.002","url":null,"abstract":"Relationships between sanukitoids and crust-derived melts and their implications for the diversity of Neoarchaean granitoids: a case study from Surmansuo and nearby areas, Eastern Finland We present new isotopic data (U-Pb and Sm-Nd) from the Neoarchean granitoids of the Lentua complex, which is a part of the Western Karelia subprovince of the Fennoscandian Shield. Compositionally, the samples are granitoids belonging to the sanukitoid suite and K-rich granitoids. Certain samples interpreted as partial melts of pre-existing crust in this study display more mafic compositions than previously described from the surrounding areas. This indicates, at least locally, a source poorer in SiO2 than the TTG (Tonalite-Trondhjemite-Granodiorite) suite granitoids, which are the likely sources for the majority of the anatectic granitoids within the Lentua complex. Based on new geochronological data (LA-MC-ICPMS U-Pb on zircon), the sanukitoids and anatectic granitoids are at least partly coeval (2.69 Ga) in the area, but interaction between the two felsic magmas was limited. The dated sanukitoid sample is distinctly younger (2687±8 Ma) than the average age of the sanukitoids of the Western Karelia subprovince (2718±3 Ma) indicating, together with one previously published sanukitoid age, the existence of a younger sanukitoid phase. This study gives new important constraints to understanding the formation of the Western Karelia subprovince by expanding the observed compositional heterogeneity and the temporal overlap of the different Neoarchean granitoid suites.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"86 1","pages":"23-40"},"PeriodicalIF":0.7,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67631034","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 age and origin of the Vaasa migmatite complex revisited","authors":"E. Suikkanen, H. Huhma, M. Kurhila, Y. Lahaye","doi":"10.17741/BGSF/86.1.003","DOIUrl":"https://doi.org/10.17741/BGSF/86.1.003","url":null,"abstract":"The origin of the Vaasa migmatite complex was studied by using whole-rock Sm-Nd and zircon Lu-Hf and U-Pb data in conjunction with whole-rock major and trace element geochemistry. The concordia ages of five Vaasa area granitoid samples are 1.88–1.86 Ga, constraining the age of peak migmatization. The ages of inherited zircon cores in the samples show two clear age populations at 2.02–1.92 Ga and c. 2.7 Ga, which correspond to ages yielded by a mica schist sample from the adjacent Evijarvi belt, as well as with published values for the Evijarvi belt zircon. The initial e Nd values of the Vaasa complex samples are relatively unradiogenic (from -3.0 to -2.0). Such values are comparable to a value (-3.6) calculated for the Evijarvi mica schist, as well as to literature values (from 3.0 to -0.5) for the Evijarvi belt. The average initial zircon e Hf values of four of the granitoids range from -10 to -5 and are in agreement with the Nd-isotopic results, whereas the northmost sample has a significantly higher value (+1). The deviation is suggested to result from disequilibrium melting of zircon. The isotopic and geochronological data indicate that the Vaasa complex granitoids formed by partial melting of the Evijarvi belt metasedimentary rocks.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"86 1","pages":"41-55"},"PeriodicalIF":0.7,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67631091","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":"Exploration methods for granitic natural stones - Geological and topographical aspects from case studies in Finland","authors":"O. Selonen, C. Ehlers, H. Luodes, P. Härmä","doi":"10.17741/BGSF/86.1.001","DOIUrl":"https://doi.org/10.17741/BGSF/86.1.001","url":null,"abstract":"Regional and local geological constraints for location of natural stone deposits in glaciated terrains of southern and central Finland have been studied and applied to practical exploration for natural stone. A list of geological and topographical aspects to be considered in exploration, is presented. Important aspects refer to: 1. Regional geology of the target area. 2. Magmatism (type and structure of intrusion, relative time of pluton emplacement). 3. Metamorphism (grade, mineral composition, parent material). 4. Deformation (lineaments, shear zones, folding, fault zones, fracture zones, shape preferred mineral orientations), and 5. Topography (relative elevation, micro topography). The proposed aspects can be used as geological guidelines in exploration for granitic natural stones.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"337 1","pages":"5-22"},"PeriodicalIF":0.7,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67631022","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":"Application of lithogeochemistry in the assessment of nickel-sulphide potential in komatiite belts from northern Finland and Norway","authors":"G. Heggie, S. Barnes, M. Fiorentini","doi":"10.17741/BGSF/85.2.001","DOIUrl":"https://doi.org/10.17741/BGSF/85.2.001","url":null,"abstract":"G.J. HEGGIE, S.J. BARNES AND M.L. FIORENTINI 1 Centre for Exploration Targeting, School of Earth and Environment, Australian Research Council Centre of Excellence for Core to Crust Fluid Systems, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia 2 CSIRO Earth Science and Resource Engineering, Australian Resource Research Centre, PO. Box 1130, Bentley, WA 6102, Australia","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"85 1","pages":"107-126"},"PeriodicalIF":0.7,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630929","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":"Development of an ancient shoreline database to reconstruct the Litorina Sea maximum extension and the highest shoreline of the Baltic Sea basin in Finland","authors":"A. Ojala, J. Palmu, A. Åberg, S. Åberg, Hanna Virkki","doi":"10.17741/BGSF/85.2.002","DOIUrl":"https://doi.org/10.17741/BGSF/85.2.002","url":null,"abstract":"An ArcGIS geodatabase called the Ancient Shoreline Database (ASD) was developed for the study and interpretation of ancient shorelines and shoreline displacement information. It was further divided into the Isolation Database (ISD) and Shoreline Landform Database (SLD) based on the characteristics of the available information. In the current study, observations related to the maximum extension of the Litorina Sea and the highest shoreline in Finland were carefully recorded and classified in the ASD. A total of 1625 shoreline observations were stored in the ASD, of which 106 were stratigraphic data points from dated isolation horizons (ISD) and the remaining 1519 were data points representing morphological shoreline observations (SLD). This paper describes the content of the ASD in terms of the variability and reliability of collated data points, but also introduces how modern LiDAR-based digital elevation models were utilized in validating the published observations as well as in interpreting new data points related to ancient shorelines from areas lacking information. The compiled ASD was used to reconstruct the diachronous maximum extension of the Litorina Sea and the highest shoreline of the Baltic Sea basin in Finland.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"85 1","pages":"127-144"},"PeriodicalIF":0.7,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630982","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":"Timing of the Baltic Ice Lake in the eastern Baltic","authors":"J. Vassiljev, L. Saarse","doi":"10.17741/BGSF/85.1.001","DOIUrl":"https://doi.org/10.17741/BGSF/85.1.001","url":null,"abstract":"A shoreline database for the Baltic, covering the Late Weichselian and Holocene, was compiled. The database includes about 1600 sites from Estonia, Latvia, Lithuania, Finland, NW Russia, Poland, Sweden and was used to create a GIS-based palaeogeographical reconstructions on the development of the Baltic Ice Lake (BIL). The formation of the highest shoreline of the BIL in Estonia was connected with the development of the Pandivere ice marginal zone (Estonia) and the lowest with the Salpausselka ice-marginal formations (Finland). There was a well-accepted knowledge that the Pandivere ice marginal zone correlates with the Neva ice marginal zone in NW Russia dated to 13 300 cal yr BP. Recent studies of the late glacial sites in northern Estonia indicate that the age of the Pandivere ice marginal zone and hence the highest shoreline of the BIL A 1 is about 13 800–14 000 cal yr BP. It was followed by the BIL stage A 2 , which formed in front of the Palivere ice marginal belt about 13 200–13 500 cal yr BP. The final drainage of the BIL took place about 11 650 cal yr BP. The timing of the BIL stages was derived from AMS- 14 C dates and correlated with varve chronology, OSL and 10 Be dates.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"85 1","pages":"9-18"},"PeriodicalIF":0.7,"publicationDate":"2013-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630615","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":"A comparative analysis of two Early Palaeozoic marine impact structures in Estonia, Baltic Sea: Neugrund and Kärdla","authors":"S. Suuroja, K. Suuroja, T. Flodén","doi":"10.17741/BGSF/85.1.006","DOIUrl":"https://doi.org/10.17741/BGSF/85.1.006","url":null,"abstract":"Kardla and Neugrund are two Early Palaeozoic offshore impact structures located some 50 km apart along the Estonian coast of the Baltic Sea. They share many similarities but differing features are also found. The Kardla impact structure is located at the NE coast of Hiiumaa Island (58°58’N, 22°46’E). The inner crater has a 4 km rim-to-rim diameter and a c. 130 m high central uplift, surrounded by a ring fault, c. 12 km in diameter. The well-preserved buried inner crater is outlined in the landscape by a circular ridge of uplifted bedrock. The perimeter of the outer crater is outlined on the seafloor by a semicircular ridge of narrow shoals. The variable height of the rim wall (50–240 m above the crystalline basement level) and the asymmetric location of the inner crater is obviously a result of an oblique impact in a layered target and partial collapse of the rim wall. Shortly after the impact in a shallow epicontinental sea during Late Ordovician time (c. 455 My), calcareous biodetritic muds were deposited and the crater was buried. The Neugrund impact structure is located in the seabed at the entrance of the Gulf of Finland (59°20’N, 23°31’E). The inner crater has a 7 km rim-to-rim diameter and the outer limit of the structure passes through the Osmussaar Island to the southwest of the impact centre. The crater was buried in a shallow epicontinental sea with siliciclastic deposition shortly after the impact at Early Cambrian time, c. 535 My. It was partially re-exposed by erosion during Pliocene. The target had a three-layered composition: Precambrian metamorphic rocks covered by Ediacaran and Early Cambrian siliciclastic rocks (c. 150 m) and water (c. 100 m). The structure has been studied with seismoacoustic and sidescan sonar profiling, and by diving and sampling of submarine outcrops. Several hundred samples of impact breccias have been collected and investigated from erratic boulders distributed by glacial action in the west Estonian mainland, islands and sea floor.","PeriodicalId":55302,"journal":{"name":"Bulletin of the Geological Society of Finland","volume":"67 1","pages":"83-101"},"PeriodicalIF":0.7,"publicationDate":"2013-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67630912","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}