Olav Eklund

• Dr.Sci.
• Professor (Full) at Åbo Akademi University

In the southernmost part of the Svecofennian province in Finland, leucogranites and migmatites stemming from both igneous and sedimentary protoliths reflect the complex magmatic history of the Svecofennian orogeny between 1.89 and 1.82 Ga. Although the migmatites and leucogranites in southernmost Finland display similar ages as their counterparts e...

Fifteen post-orogenic, basic to acidic High-Barium-Strontium (HiBaSr) intrusions of shoshonitic affinity have been recognized in central and southern Finland. Most of the intrusions are found in a 500 km long E–W-trending belt in the Southern Finland Subprovince, with three of them in the Western Finland Subprovince. These rocks have distinctive fi...

Kiirunavaara in northernmost Sweden hosts the largest so far known iron oxide-apatite (IOA) ore body worldwide (>2000 Mt of pre-mining ore). It was also the first IOA deposit subjected to detailed scientific study as to geological relations and origin (Geijer 1910). Here we concentrate on a group of porphyry dykes (DPs) that penetrate the foot wall...

High-shear exfoliation of graphite is a cost-effective liquid-phase exfoliation (LPE) method for producing few-layer graphene dispersions. However, the drawbacks of LPE such as low graphene concentrations, long processing times and solvent residuals hamper the scalability of the process and applicability of the dispersions. Here, we demonstrate a f...

Southern Finland consist of belts of migmatitic infra-and supracrustal rocks. The southernmost migmatitic belt and Uusimaa belt have coeval and presumably similar tectonic histories, although it is proposed that they are separated by a terrane boundary. In this study, we investigated leucosomes, granitic intrusions and deformation history in the so...

Leucosome sizes in migmatites has been shown to follow power-law distribution, which is indicative of self-organized criticality governing accumulation and transport of partial melts in anatexis. In our measurements of leucosome widths in the Olkiluoto migmatite in western Finland, we found double power-law distributions in addition to single power...

The flake graphite occurrence in Piippumäki, Eastern Finland, as indicated by an airborne electromagnetic anomaly, was located during fieldwork by electromagnetic measurements with Slingram. The anomaly is approximately 0.1 × 1 km in size. The flake graphite is hosted by quartz-feldspar gneiss and amphibolite that have been subjected to retrograde...

Tectonic evolution of the Paleoproterozoic Vaasa migmatitic complex (VMC) in the central part of the Svecofennian accretionary orogen is deciphered using aeromagnetic and gravity maps, deep seismic and magnetotelluric profiles, and structural and metamorphic data. The VMC is a semicircular structure with migmatitic rim and granitic core composed of...

Vermiculite is a mineral with many potential uses in various industrial areas, such as in insulation, horticulture, and environmental applications. The regolith of the Sokli carbonatite intrusion in northern Finland consists of weathered micas which reportedly contain vermiculite. The aim of the present study was to characterize the weathered mica...

The Paleoproterozoic Svecofennian orogenic domain of Southern Finland consists principally of belts of strongly migmatized infra- and supracrustal rocks in upper amphibolite to granulite facies, with areas of less migmatized rocks in between. The granite-migmatite belts are presumably related to each other. However, the relationship between the for...

The Vaasa migmatitic complex (VMC), which is a part of the Paleoproterozoic Svecofennian accretionary orogen, has been studied by geological and geophysical methods. Lithological, structural, geochronological (U/Pb) and geophysical (MT and seismic reflection sections, aeromagnetic and gravity maps) data are used to interpret the structure and forma...

For the first time, the ammonium sorption from a municipal solid waste landfill leachate into the natural and nanomodified vermiculite mineral (NMV) were examined. NMV is a novel material developed to further improve the excellent ammonium absorption capacity of vermiculite. It can be prepared by heat treatment of natural raw vermiculite. In this s...

The Paleoproterozoic Svecofennian orogenic domain of Southern Finland consists principally of belts of strongly migmatized infra- and supracrustal rocks and granitoids in upper amphibolite to granulite facies, with areas of less migmatized rocks in between. The granite-migmatite belts are presumably related to each other. However, their structural...

The earliest Svecofennian magmatism in southern Finland has been dated at 1.90-1.88Ga. As an example of this, the Orijärvi (ca. 1.89Ga) and Enklinge (ca. 1.88Ga) volcanic centres comprise bimodal plutonic batholiths surrounded by volcanic rocks of comparable ages and chemical compositions. Here, we report geochemical and Sm-Nd isotope data from int...

The principle of the ÅA route method for mineral carbonation is to produce magnesite from Mg cations extracted from silicates, precipitate Mg as Mg(OH)2 and fuse it with CO2 to produce magnesite (MgCO3). Since Mg is situated in distinct parts of the crystal lattice in different silicate groups, it varies from group to group how easily Mg can be ext...

The magmatic history of batholiths formed as the result of tectonic accretion mirrors the evolution of the underlying crust from island arcs to accretion and collapse. Chemical composition, age and structure give information about the magma source and emplacement depths. The target of this study is the Central Finland batholith (CFGC) that provides...

Serpentinite rocks are considered to be a suitable raw material for Carbon Capture and Mineralization (CCM), which has been recognized as a potential method for the management of the industrial CO2-emissions. Different serpentine minerals, that form serpentinite rocks, feature divergent characteristics that influence the eventual suitability of a s...

The aim of this study has been to determine the quality of flake graphite in high-grade metamorphic rocks in Sortland, Vesterålen, northern Norway. Flake graphite is present in graphite schist and samples were collected at three different locations, Hornvatnet, Lamarkvatnet and Vikeid. The host rocks of the graphite schist are dolomite or calcite m...

Arc-collisional batholiths may record their magmatic history from an arc to arc-collision zone, hence the batholiths mirrors the underlying crustal evolution. Change in the geochemical composition, age and structure can give direct and indirect information of the changing tectonic setting. We have used the Central Finland granitoid complex (CFGC) i...

Geodynamic models offer insight into deformation styles of syn- and post-collisional extensional processes. Such models often ignore the effect of lateral viscosity contrast between accreted terranes and inherited tectonic boundaries. This paper presents a set of crustal-scale analog experiments of one-way post-collisional gravitational spreading t...

We report new palaeomagnetic and isotope age data of Early Mesoproterozoic (i.e. Subjotnian) intrusions from the åland archipelago, SW Finland. The palaeomagnetic results reveal dual-polarity magnetizations with a pronounced reversal asymmetry occurring in dykes. We explain the asymmetry by an unremoved secondary component, which is affecting more...

Over-thickened orogenic crust may suffer from rheological, gravitational and topographical unbalancing resulting in discharging via gravitational spreading. If the thickened orogen is also hot, then increased temperature may reduce the viscosity of the crust that may induce large-scale horizontal flow. The effect of flow on the crustal architecture...

The Paleoproterozoic Svecofennian orogenic domain encloses the Central Finland granitoid complex (CFGC). The complex consists of plutonic rocks and minor amounts of supracrustal and subvolcanic rocks. The magmatism is associated with syn- and post-convergent orogenic events at 1890-1870 Ma. However, the age data is defective with major uncertaintie...

The aim of this study was to compare different types of dolomites through batch reactivity experiments between HCl and dolomite powders, and ex-situ characterisation of the particles before and after dissolution. Sedimentary dolomites were observed to have higher initial reactivities than metamorphic ones with sufficiently low calcite concentration...

Orogenesis can develop at different scales and between different plate types and may result in overthickening of the crust and thus post-collisional extension (Beaumont et al. 2001). This paper presents crustal scale structures of unilateral gravitational spreading in three-layered crust at post-collisional stage using analogue centrifuge models....

In the Paleoproterozoic Svecofennian orogenic domain of the Fennoscandian shield, the large Central Finland Granitoid Complex (CFGC) consists of plutonic rocks and minor amounts of supracrustal rocks. The CFGC has a geological history that is only vaguely known. The metamorphic culmination of the Svecofennian orogen occurred at about 1890 Ma. The r...

Petrographic, geochemical, and geochronological data from shoshonitic lamprophyres from the North Savo region, eastern Finland, and the NW Ladoga region, northwest Russia are presented. The two areas are found ~ 250 km apart along a roughly 450 km long palaeosuture between the Archaean Karelia Craton and the Proterozoic Svecofennian Domain. Two of...

For Finland, carbon dioxide mineralisation was identified as the only option for CCS (carbon dioxide capture and storage) application. Unfortunately it has not been embraced by the power sector, partly because the most suitable mineral resources are found in central and northern Finland while most fossil-fuel fired electricity production is located...

The exposed Svecofennian crust (50-65 km) has been suggested to have thickened in continental accretion between Archean and Paleoproterozoic terranes, probably at a high convergence rate. It is likely that this thickened orogen experienced lateral spreading during its final stages. This post-orogenic event has reshaped the collisional framework and...

With the aim to visualize the span of time since the formation of our Universe we have set up a nature and hiking trail called `Time Trek'. The 13.7 km length of the trail corresponds to the age of the Universe, and portrays its history including events important for Earth and life. One kilometre corresponds to a billion years, and one metre to a m...

The Palaeoproterozoic Svecofennian orogen in the Fennoscandian shield is an arc accretionary orogen that was formed at c. 1.92-1.86Ga. Arc accretion, magmatism and the subsequent continent-continent collision thickened the crust up to c. 70km, forming one of the thickest Palaeoproterozic orogens. At the end stage of accretionary tectonics, volumino...

The purpose of this paper was to study the usability of new ammonium absorber material as fertilizer. The vermiculite-material which effectively binds ammonium nitrogen to its structure has been developed to remove ammonium ions from waste waters. The material is further developed for fertilizer use. At first step the absorption material was proces...

We have studied plutonic rocks from the Korpo and Rauma areas of south-western Finland which can be categorized as intra-orogenic, i.e. they were intruded during a proposed extensional period between the two main Svecofennian orogenic cycles: the Fennian and Svecobaltic orogenies. The diorite from Rauma yielded an age of 1865 ± 9 Ma and the diorite...

The dissolution of seven natural limestones and calcareous rocks in hydrochloric acid solution was examined to investigate their capability for wet flue gas desulphurisation. All samples were crushed, ground and sieved to a size-fraction of 150-250mm. Thereafter they were subjected to a dissolution experiment utilising stepwise titration with hydro...

The Åva ring intrusion is one of four post-collisional shoshonitic ring intrusions situated in the archipelago of SW Finland. The Åva ring intrusion is about 7 km in diameter, and contains hundreds of ring dykes varying in width between 10 cm and 5 meters. These consist principally of coarse K-feldspar-phenocrystic granite, mingled in places with e...

Whole-rock and isotope geochemistry of six ∼1.8 Ga post-kinematic intrusions, emplaced along the ∼1.9 Ga Southern Svecofennian Arc Complex (SSAC) and in the SW part of the Karelian Domain in Finland, was studied. The intrusive age [U–Pb secondary ion mass spectrometer (SIMS)] of one of these, the Petravaara Pluton, was determined as 1811 ± 6 Ma. Ba...

Jakob Johannes Sederholm (1863–1934) was one of the more influential pioneers in Precambrian geology having introduced some fundamental insights and concepts which are still relevant today. Towards the end of the 19th century, he demonstrated how the principle of actualism can be applied to Precambrian terranes, while during the early part of the 2...

We present a set of analogue experiments simulating the extensional collapse of the Svecofennian orogeny. The experiments were conducted in a new thermomechanical deformation apparatus at Frankfurt University using plasticine as an analogue material. Layered models (upper crust, middle crust and lower crust) were constructed and subjected to extens...

CARETECH is a multidisciplinary project supported by the Academy of Finland. The aim of this project is to determine the best natural materials that can be used in desulphurization and carbonation processes using methods from materials science, mineralogy and geology. In this paper, we discuss various properties of limestones, such as the chemical...

Abstract The inspiration for the Sederholm Symposium at the 33rd IGC in Oslo, and this related excursion was to acknowledge the passing, in the year 2007, of one hundred years since J.J. Sederholm (1863 – 1934) published his paper "Om granit och gnejs, deras uppkomst, uppträdande och utbredning inom urberget i Fennoskandia " (On granite and gneiss,...

To receive detailed information about the history coarse porphyritic ganites from different tectonic setting (post- and anorogenic), mineral inclusions in quartz and K-feldsparmegacrysts were studied. The result of the project was that the megacrysts were formed in mid-crustal magmachambers some 30 Ma before the emplacement of the granites in the u...

The compositional zoning of plagioclase-mantled K-feldspar, defining the rapakivi texture, and of the associated quartz phenocrysts from the Paleozoic Land’s End (U.K.) and Altenberg–Frauenstein (Germany) granites, and the Proterozoic Hammarudda (Finland) granite porphyry, has been investigated by laser-ablation – inductively coupled plasma – mass...

The early Svecofennian magmatism in southern Finland consists of two main periods: the synvolcanic 1.90-1.88 Ga and the synorogenic 1.88-1.86 Ga periods. The synvolcanic Sve-cofennian plutonism in both Finland and Sweden is associated with volcanic rocks in time as well as in space. We have studied two synvolcanic magmatic complexes from SW Finland...

Poster

The Tien Shan (Tianshan) orogen formed during Late Palaeozoic collision between the Karakum–Tarim continent and the Paleo-Kazakhstan continent, a Caledonian component of the Altaid Collage. The Southern Tien Shan terrane represents an intensely deformed fold and thrust belt formed after the final closure of the Paleo-Turkestan ocean. In the Late Ca...

New palaeomagnetic and rock magnetic data are presented from Palaeoproterozoic 1.8 Ga shoshonitic intrusions and associated NW-SE trending lamprophyre dykes, and from undated NE-SW trending dolerite dykes at Lake Ladoga area in NW Russia. The shoshonitic intrusions and lamprophyre dykes are suggested to carry a primary 1.8 Ga remanent magnetization...

The Ladoga, Russia, and adjacent Sulkava, southeastern Finland, metamorphic complexes are the two largest “granulite” provinces of the Svecofennian domain. In this area, the domain is composed of outer and inner zones. Sulkava is situated in the inner zone, which principally can be compared to the accretionary arc complex of Southern Finland. Ladog...

The ca. 1.8 Ga post-collisional magmatism in the southern part of the 2.1–1.86 Ga Svecofennian domain of the Fennoscandian Shield have been studied with particular reference to the character and sources of the mafic rocks in a traverse from the Archaean craton margin in east, across the juvenile Svecofennian domain to its western margin. For this p...

Abstract: Across southern Finland the Late Svecofennian Granite Migmatite zone contains large amounts of migmatites and S-type granites formed during the high temperature and low pressure metamorphism between 1.84 and 1.80 Ga. Within this zone, the Karjaa granite intrudes the surrounding migmatites. The granite is more fine-grained and darker than...

The Åva ring complex is one of four Paleoproterozoic postcollisional shoshonitic ring complexes in southwestern Finland. It is composed of ring dykes of K-feldspar megacryst-bearing granite, mingled in places with a shoshonitic monzonite, and lamprophyre dykes crosscutting all the rocks in a radial pattern. A survey was undertaken to trace the magm...

We report here 40Ar/ 39Ar whole-rock and sericite data for host-rock (sericite-quartz altered rock) and gold ore (pyrite-quartz-feldspar-carbonate) from the giant Kumtor gold deposit in the Tien Shan fold and thrust belt of Kyrgyzstan, one of the largest orogenic gold belts on Earth. Plateau ages for whole-rock samples of sericitequartz altered roc...

Charnockites are either plutonic or metamorphic orthopyroxene-bearing quartzofeldspathic rocks. This study shows that the charnockitic rocks within the Turku granulite area were formed under granulite facies conditions from tonalitic granitoids through charnockitization reactions. Biotite and amphibole reacted with quartz to form pyroxene, plagiocl...

The Transscandinavian Igneous Belt (TIB) comprises a giant elongated array of batholiths extending c. 1400 km across the Scandinavian Peninsula from southeasternmost Sweden to northwestern Norway. The TIB is traditionally divided into four main units based on tectonic and lithological criteria: i) the Småland-Värmland belt in the south and west, ii...

Two case studies was undertaken to investigate the residence time in the middle crust for coarse-grained granites before emplacement in the upper crust. One is a post-orogenic high Ba-Sr granite (Åva) and the other an anorogenic rapakivi granite porphyry (Järppilä). Both from the paleo-proterozoic accretionaly arc-complex of southern Finland. Zirco...

The Puutsaari intrusion is a potassium-rich magmatic complex in the eastern part of the Svecofennian domain close to the Archaean border. The intrusion is generally undeformed in contrast to 1880–1875 Ma-old country rock tonalitic migmatites and diatectites. The main rock types are: (1) mafic rocks of a gabbro–norite–diorite–quartz monzodiorite ser...

The rapakivi texture (plagioclase-mantled K-feldspar ovoids, rounded quartz megacrysts and euhedral plagioclase megacrysts in a more fine-grained granitic matrix) has been studied in five Proterozoic (1.64–1.55Ga) anorogenic rapakivi granite batholiths in the Fennoscandian Shield with emphasis on mineral stability and inherited cores. K-feldspar ov...

At least 14 small (1–11 km across) 1.8 Ga Svecofennian post-collisional bimodal intrusions occur in southern Finland and Russian Karelia in a 600-km-long belt from the Åland Islands to the NW Lake Ladoga region. The rocks range from ultramafic, calc-alkaline, apatite-rich potassium lamprophyres to peraluminous HiBaSr granites, and form a shoshoniti...

1.8 Ga Svecofennian bimodal complexes in Russian Karelia comprise an eastern branch of 600 km long belt extending from Åland Islands to the NW Ladoga region. The rocks range from ultramafic, calc-alkaline, apatite-rich potassium lamprophyres to HiBaSr granites, and form a shoshonitic series with K2O + Na2O > 5%, K2O/Na2O > 0.5, Al2O3 > 9% over a wi...

Indicative rock-forming minerals from a variety of textural components of mafic hybrid labradorite-bearing enclaves and their host quartz-feldspar rapakivi porphyry of the Hammamdda Complex, Åland Massif, southwestern Finland, were studied to determine the interaction conditions of the basite and acid magmas. Comparing the composition of the pyroxe...

A flow-foliated felsic ignimbrite constitutes the uppermost lithological unit of the 1.58 Gyr anorogenic magmatic rocks in SW Finland. The ignimbrite is derived from an explosive eruption of hot (≅ 950 °C) phenocryst-bearing A-type (rapakivi-type granite magma. The ignimbrite is close in composition to subvolcanic rapakivi granites that occur in th...

Finely cellular plagioclase intergrowths have been studied in xenocrystic andesine (An32) and andesine mantled K-feldspars within mafic magmatic enclaves in a quartz-feldspar porphyry from the Proterozoic subvolcanic Hammarudda complex, land rapakivi batholith, SW Finland. The cellular intergrowths usually occur as 0.2–2.0 mm mantles around xenocry...

The Åland, rapakivi batholith consists of several granites that differ texturally and mineralogically from quartz-porphyritic varieties to rapakivi varieties with K-feldspar ovoids (wiborgites and pyterlites) and aplitic granites. Closely associated with the batholith there is a mafc magmatic series of dolerite dykes, norites, anorthosites and monz...

Southwest of the Middle Proterozoic Åland rapakivi batholith (1575 Ma) there occur dolerites closely associated with quartz-feldspar porphyries. The dolerites and the quartz-feldspar porphyries were formed during a bimodal igneous event characterizing the initial stages of the rapakivi intrusion. A coarse-porphyritic porphyry carries abundant mafic...

Middle Proterozoic dykes and sills of mostly continental tholeiitic composition occur along the contact between the Middle Proterozoic Åland rapakivi batholith and the Early Proterozoic Svecofennian country rock of southwestern Finland. These dykes and sills have interacted with their granitic wallrocks in different ways. The dykes in two studied l...

The Lemland intrusion is one of four postorogenic (1815-1770 Ma) granitoid intrusions occurring in southwestern Finland. The intrusions are dominated by porphyritic granite and basic-intermediate rocks. They show features of a bimodal magmatism, causing net-veining and formation of mixed rocks.The current investigation of the southern part of the L...