Markku Väisänen

Markku Väisänen
University of Turku | UTU · Department of Geography and Geology

PhD

About

47
Publications
12,353
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
863
Citations
Citations since 2017
16 Research Items
246 Citations
201720182019202020212022202301020304050
201720182019202020212022202301020304050
201720182019202020212022202301020304050
201720182019202020212022202301020304050

Publications

Publications (47)
Article
Full-text available
The Mawat ophiolite, NE Iraq, is one of the Neo-Tethyan ophiolites within the Iraqi Zagros orogen. It consists of many metre-to kilometre-sized tectonic slices of serpentinized dunite, peridotite, gabbro, basaltic rocks and associated oceanic metasediments. Felsic intrusions crosscut the ophiolite. We present U-Pb zircon and monazite ages and Hf zi...
Article
Full-text available
Arclogites, i.e., lower crustal garnet-pyroxenite cumulates, are suggested to play an important role in controlling magma differentiation in modern continental arcs. Until now, arclogite-related magmatism has only been described from the Phanerozoic Era. The Svecofennian orogen in the central Fennoscandian Shield hosts a rare association of 1.86 Ga...
Article
Full-text available
The Mawat ophiolite is a fragment from the Neo-Tethyan oceanic lithosphere and is considered as the largest and best-exposed ophiolite within the Zagros Suture Zone, northeast Iraq. Felsic dykes are encountered in three locations in the Mawat ophiolite. Here, we use field work, petrology and geochemical data to investigate the magma sources of the...
Article
Full-text available
We characterise the geochemistry, zircon Lu-Hf composition, age and the structure of the Uunimäki gabbro (UGB) in south-western Finland to improve the understanding of i) the early Svecofennian (1.92–1.89 Ga) crustal evolution of the central Fennoscandian Shield, ii) the potential role of rift-related magmatism for the build-up of the Paleoproteroz...
Article
Full-text available
The E-MORB type Haveri basalt differs from the volcanic arc type rocks in the Tampere belt showing no subduction signature. It is considered to have formed in a marginal basin prior to the volcanic arc. We present here zircon U-Pb dating on two samples. The basalt and the felsic dyke yielded 207Pb/206Pb ages of 1902 ± 5 Ma and 1891 ± 2 Ma, respecti...
Article
Full-text available
New geochemical data were presented for the mafic (basalts and gabbros) and ultramafic (dunites, serpentinites and pyroxenites) rocks from the Mawat ophiolite exposed in the Zagros suture zone in northeastern Iraq. The mantle section of the ophiolite is composed of serpentinized peridotites, harzburgites, dunites, chromitites and pyroxenite dykes....
Conference Paper
Full-text available
Lieksa-4 is an iron meteorite find from Löpönvaara, Lieksa. The meteorite consists of approximately 84 wt% Fe, 11 wt% Ni, and 4 wt% P. Trace elements Ga, Ge, Au, and Ir occur in low abundances. The sample consists mainly of rounded kamacite granules in a schreibersite-matrix. Troilite occurs in the matrix in low abundances. Moreover, Neumann deform...
Conference Paper
Full-text available
The Central Svecofennian Arc Complex (CSAC) and the Southern Svecofennian Arc Complex (SSAC) show different ages of peak metamorphism: ~1.88 Ga in the CSAC and ~1.83 Ga in the SSAC. In the present project we study the age of the metamorphism in SW Finland. We have collected two samples. Of these the Eurajoki leucosome zircons were > 1.92 Ga, i.e.,i...
Conference Paper
Full-text available
The bedrock of the Salo area in SW Finland is mainly occupied by granitoids. We dated five granitoids and two mafic volcanic rocks with single zircon method. The granitoids fall in two age groups, 1.86-1.85 and 1.83-1.82 Ga. Mafic plutonic rocks occur in both age groups. The volcanic rocks are 1.90 and 1.89 Ga in age. Further, the samples display t...
Conference Paper
Full-text available
We sampled one felsic volcanic rock from the lower part of the Kisko formation and two cordierite-anthophyllite rocks from Orijärvi and Iilijärvi for U-Pb dating. The felsic volcanic rock yield a zircon 207 Pb/ 206 Pb weighted average age of ~1.89 Ga. The oldest zircons from the Orijärvi cordierite-anthophyllite rock give a weighted average age of...
Article
Full-text available
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...
Poster
Full-text available
High Field Strength Element ratios, in particular Nb/Ta and Zr/Hf (~17,5 and 36, respectively; Sun & McDonough 1989), in the unfractionated Earth are assumed to follow those of the chondrites. However, the Nb/Ta ratio of the Earth’s crust and mantle show subchondritic values (~ 12-15) which have led to so-called “Nb/Ta paradox” and searching for a...
Article
Full-text available
Because of the relatively low metamorphic grade, low strain and well-preserved early structures in volcanic and volcaniclastic rocks, the Orijärvi triangle (in the center of the larger Orijärvi area) is one of the few locations in the Svecofennian orogen of southern Finland where lithostratigraphy has been determined. The geochemistry of the picrit...
Conference Paper
Full-text available
We describe here a newly discovered cross-cutting mafic dyke in the vicinity of Lohja, southern Finland. The dyke is E-W trending and about 6 m in width. Only a few zircons were recovered from the dyke despite the high Zr contents and they all were inherited. Therefore, the crystallisation age remains uncertain. The dyke is shoshonitic in compositi...
Conference Paper
The geochemical composition of seven post-kinematic mafic dykes in southern part of Central Svecofennia have been studied. Two dykes have been selected for in situ zircon U-Pb geochronology and one for in situ zircon Lu--Hf isotope analysis. These c. 1.86 Ga dykes can be divided into two subgroups by their geochemical characteristics: i) an enriche...
Conference Paper
Full-text available
The bedrock in southern Finland was affected by high temperature/low pressure metamorphism (c. 600-800 °C/4-6 bars) late in the orogeny causing widespread crustal melting. Heat source for this is controversial. Previously, mafic intraplating or under-plating was suggested as heat sources. Lately, Kukkonen and Lauri (2009) suggested that crustal thi...
Conference Paper
Full-text available
The Svecofennian bedrock in the Salo area in SW Finland comprises granitoids and migmatised metasedimentary and metavolcanic rocks, metamorphosed in higher amphibolite and granulite facies conditions. The area is characterised by subhorizontal structures in large areas. We performed U-Pb zircon and monazite age determinations on two granites using...
Article
Full-text available
Using single-grain zircon U-Pb dating by LA-MC-ICPMS and whole-rock geochemistry, we have studied the Palaeoproterozoic gabbroic rocks from Moisio in southwest Finland. Three ages were obtained. The interpreted intrusion age is ~1.86 Ga, which places it in the 1.87–1.84 Ga intra-orogenic period of southern Svecofennia. The other ages, ~1.89 Ga and...
Conference Paper
Full-text available
We present single-grain zircon U-Pb laser-ablation data from gabbroic rocks in three locations in southern Finland. In Ruissalo, Turku, the mafic intrusions are found within the Airisto shear zone with ages of c. 1.83-1.82 Ga. In Muurla, the c. 1.81 Ga granite cuts across the c. 1.83-1.82 Ga gabbro. In Salittu, Karjalohja, the 1.83-1.82 Ga mafic dy...
Conference Paper
Full-text available
This paper presents a number of hypotheses on the crustal evolution of the Salo area in SW Finland. The working hypotheses will be tested using a multidisciplinary approach comprising structural analysis, 3/4D-modelling, isotope geology and geochemistry. The project is expected to provide new insights into the complex orogenic evolution of the Fenn...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
Zircons from a felsic volcanic rock in the Toija Formation and a synvolcanic gabbro intrusion in the Salittu Formation within the Orijärvi area were dated by U-Th-Pb SIMS in order to provide depositional constraints on these formations. Zircon crystals from the felsic rock preserve a two-stage crystallisation history with zoned core domains and hom...
Conference Paper
Full-text available
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,...
Article
Full-text available
Twenty two samples were analysed from mafic and intermediate volcanic rocks from the Turku area along ~60 km long north-south geotraverse. Geographically and lithologically the samples were divided into the Pargas, Turku and Vahto groups. The Pargas and Turku groups consist of mafic units and intercalations within migmatitic gneisses. Their geochem...
Article
Full-text available
The bedrock of southwestern Finland is transected by a shear zone network with two dominant directions: ∼E-W and ∼N-S. The shear activity occurred after peak metamorphism and crustal melting at 1840-1810 Ma. The shear zones began to form as a consequence of north vergent oblique continent-continent collision and accommodated the resulting dextral t...
Article
Full-text available
Three main ductile deformations, D1-D3, and contemporaneous and later shear zones account for most structures in Central Lapland. The oldest tectono-metamorphic feature is the bedding-parallel, mostly microscopic S1, overprinted by the main foliation S2, which is the most prominent structural feature seen in almost all rock types throughout the stu...
Article
The predominantly migmatitic Palaeoproterozoic Uusimaa belt preserves early lower-grade Svecofennian structures in the Orijärvi area in SW Finland. This study aims at explaining the deformational history responsible for its preservation and also at defining the age of the early Svecofennian deformation. Detailed structural analysis reveals that the...
Article
Full-text available
The 100 km wide late Svecofennian granite-migmatite zone in southern Finland contains the Sulkava, the Turku and the West Uusimaa low-pressure, high-temperature granulite areas. In the West Uusimaa area the peak metamorphic conditions are estimated at T = 750–800°C and P = 4–5 kbars. Detailed isotopic dating of different parts of migmatites (mesoso...
Article
Full-text available
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...
Conference Paper
Full-text available
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...
Article
Full-text available
The Orijärvi area within the Uusimaa Belt is a key area in resolving the stratigraphy and tectonic setting of the Southern Svecofennian Arc Complex in southern Finland. Based on field relationships, geochemistry and radiometric age determinations, the area can be divided into four formations. The bimodal Orijärvi formation, lowermost in stratigraph...
Article
Zircons from six samples collected from igneous and metamorphic rocks were dated using the NORDSIM ion microprobe, in order to investigate the tectonic evolution of the Palaeoproterozoic Svecofennian Orogen in southwestern Finland. These rocks represent pre-collisional, collisional and post-collisional stages of the orogeny. The ion microprobe resu...
Article
Five bimodal post-collisional intrusions in southwestern Finland have been investigated. Geochemically, the mafic rocks are shoshonitic monzodiorites, which are highly enriched in Fe, P, Ti, F, LREE and in incompatible trace elements. The felsic rocks are garnet bearing peraluminous, S-type anatectic granites. New data on the mafic and the felsic i...
Article
Full-text available
The Turku migmatite complex in southwestern Finland is a representative area for the type of tectonic and metamorphic evolution seen within the Palaeoproterozoic Svecofennian Orogen in southern Finland. The orogeny can be divided into early, late and postorogenic stages. The early orogenic structural evolution of the crust is expressed by a D1/D2 d...
Article
Full-text available
The Global Geoscience Transect SVEKA (GGT/SVEKA), a 160 km wide, 840 km long strip in the central part of the Fennoscandian shield, covers the western part of the Archean Karelian Province in the northeast, crosses the boundary zone between the Karelian Province and the Paleoproterozoic Svecofennian arc complex, traverses the main tectonic units of...

Network

Cited By

Projects

Project (1)