Geochemistry, U-Pb geochronology and Sm-Nd data from the Paleoproterozoic Western Finland supersuite – A key component in the coupled Bothnian oroclines

Lahtinen, Raimo; Huhma, Hannu; Sipilä, Pekka; Vaarma, Markus

doi:10.1016/j.precamres.2017.07.025

Cited by 17 publications

(14 citation statements)

References 64 publications

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“…Recently, Lahtinen et al (, ) proposed that the folded architecture of the conductor anomaly in the map view results from the buckling of the linear accretionary system from 1.87 to 1.86 Ga due to dextral transpression along the Karelian continental margin. Our data are fully compatible with this model (Figure b), where the regional N‐S shortening (D2) marks the start of the orogenic buckling and the southward migration of the accretionary system (Bogdanova et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…Luukas et al () divided the Finnish part of the Svecofennian orogen into the Southern and Western Finland Subprovinces (Figure a); the latter being divided into the Central Finland Granitoid Complex (CFGC) and the Savo, Tampere‐Pirkanmaa, and Pohjanmaa schist belts (Nironen et al, ). The CFGC, interpreted as a typical root zone of a magmatic arc (Rämö et al, ), comprises mainly (I‐type) calc‐alkalic to alkali‐calcic granitoids (1.89–1.87 Ga; Nironen et al, , Nikkilä et al, ) with minor amounts of mafic plutonic rocks and comagmatic volcanic sequences (Kähkönen, ; Korsman et al, ; Lahtinen et al, ; Nironen et al, ). It is surrounded by schist belts (Savo, Tampere‐Pirkanmaa, and Pohjanmaa schist belts) made of supracrustal (meta)sediments (greywackes and pelites) and volcanic rocks.…”

Section: Geological and Geophysical Settingmentioning

confidence: 99%

“…The geodynamic and tectonic models driving the accretionary process are, however, under debate. Hermansson et al () suggested advancing and retreating subduction zones; Nikkilä et al () suggested accretion followed by collapse; Cagnard et al () suggested distributed thickening and lateral flow; and Lahtinen et al () proposed a model where the linear accretionary system is later buckled forming coupled oroclines (Lahtinen et al, ). Based on surface structural observations, Cagnard et al (, ) suggested that Southern Finland Subprovince of the Svecofennian orogeny (Figure ) has suffered from horizontal shortening, lateral and vertical mass and heat transfers resulting in the formation of pop‐down structures, and exhumation of partially molten deep rocks (Chardon et al, ; Gapais et al, ).…”

Section: Introductionmentioning

confidence: 99%

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The Vaasa Migmatitic Complex (Svecofennian Orogen, Finland): Buildup of a LP‐HT Dome During Nuna Assembly

et al. 2020

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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 several subdomes. It evolved in three main tectonic events (D1-D3). The D1 event (ca. 1.89-1.88 Ga) corresponds to the stacking of supracrustal rocks and the formation of an inverted metamorphic gradient. Anatexis at LP-HT metamorphic conditions enabled the material to flow. The D2 event (ca. 1.88-1.87 Ga) corresponds to large-scale folding of the partially molten crust within an orocline. It is marked by folds with an E-W vertical axial planar foliation. The late D3 event resulted from mass redistribution owing to mechanical instabilities within the hinge of the orocline. It is marked by vertical shearing (ca. 1.87-1.85 Ga) in the marginal parts of the complex and along the granitoid subdomes. The seismic reflection profile (FIRE 3a) and magnetotelluric profiles (MT-PE and MT-B2) image large-scale D1 stacking structures within an accretionary prism. Near vertical breaks in crustal-scale reflectivity and conductivity models are interpreted as D3 shear zones. The VMC is an example of early mass and heat transfer within a collage of hot supracrustal rocks in an accretionary belt. Partial melting enhanced the flow of material, the production, and rise of magma as well as exhumation, marked by magmatic domes in the hinge of the orocline.

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Section: Discussionmentioning

confidence: 99%

Section: Geological and Geophysical Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Vaasa Migmatitic Complex (Svecofennian Orogen, Finland): Buildup of a LP‐HT Dome During Nuna Assembly

et al. 2020

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“…17 have variable amounts of Archean detrital zircons (15-50%) but no clear trend has been noticed so far. Mixing of the Viinijärvi and Näläntöjärvi suites with a 1.92-1.93 Ga source could explain the Svecofennian (TB+PB+HB) distribution pattern but variable 1.97-2.00 Ga sources are probable (Lahtinen et al, 2009(Lahtinen et al, , 2017. A distribution pattern of the Uusivirka and Ristivuoma metasedimentary rocks is different and implies different source characteristics.…”

Section: Tectonic Implications and Correlationsmentioning

confidence: 97%

“…PB+TB+HB (Fig. 1 inset) data from Lahtinen et al (2009Lahtinen et al ( , 2017; Viinijärvi suite data (samples A191, A676, A1172, A1631, A1632) from Lahtinen et al (2010;including data from Huhma et al, 1991 andClaesson et al, 1993); Näläntöjärvi suite data (samples A1979, A1984, A1985, A1986) from Lahtinen et al (2015c).…”

Section: Tectonic Implications and Correlationsmentioning

confidence: 99%

Geochemical and U-Pb and Sm-Nd isotopic constraints on the evolution of the Paleoproterozoic Ylitornio nappe complex, northern Fennoscandia

Lahtinen¹,

Huhma²,

Lauri³

et al. 2019

Bull Geol Soc Finland

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The Ylitornio area in northern Finland is a typical example of a poorly outcropping, multiply deformed, complex Precambrian terrain. U-Pb, Sm-Nd and geochemical data from metavolcanic, metasedimentary and plutonic rocks combined with structural data define the lithodemic units and tectonostratigraphy of the area. The Mellajoki, Martimo, Hosiojoki, Kierovaara and Uusivirka suites form the Ylitornio nappe complex. Although main thrust stacking had occurred between 1.92-1.89 Ga, later reverse faulting probably continued until 1.78 Ga. The Väystäjä bimodal volcanic rocks (2.09-2.05 Ga) from the Martimo suite are plume-related EMORB-OIB rocks formed during a continent breakup. The Kaskimaa greywacke of the Martimo suite is inferred to represent sedimentation in a deepening rift basin in the continental margin. The coeval Hosiojoki felsic rocks with A-type affinity and the Kierovaara suite granites (2.00-1.98 Ga) represent dry melting of a dominantly 2.1-2.05 Ga contaminated mafic underplate, and hydrous melting of both the mafic underplate and a refractory lower crust of Archean age, respectively. The older rocks of the Uusivirka suite are early-collisional (1.92-1.91 Ga) and derived from poorly mixed local sources, whereas younger psammite-pelite associations (Ristivuoma) are syn-collisional (1.91-1.89 Ga) and derive from multiply recycled and thoroughly mixed sources. These rocks were deformed during continued collision with the development of foreland fold-and thrust belt.

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Contribution of bedrock structures to the bedrock surface topography and groundwater flow systems within deep glaciofluvial aquifers in Kurikka, Western Finland

Ruuska

Skyttä

Putkinen

et al. 2023

Earth Surf Processes Landf

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One of the key challenges related to glaciofluvial aquifers is understanding how the underlying bedrock structures and the associated bedrock surface topography contributed to the deposition of the glaciofluvial sediments and the generation of groundwater flow pathways. In this study from Western Finland, we present a new digital elevation model of the Precambrian crystalline bedrock surface buried up to 100 m beneath the glaciofluvial sediments along the Kurikka depression. We link bedrock topography to structural anisotropy using additional data from rock outcrops, boreholes and gravity data. Brittle deformation zones are seen in the bedrock‐digital elevation model (DEM) as sharp breaks in the rock surface. These vertical fracture zones contributed to the development of interlinked elongate bedrock depressions and delimit rock blocks with different elevations. A narrow, zigzagging trench, with a stepped floor, follows WNW‐ESE and NE‐SW oriented fracture zones and forms a major hydraulic connection between two major parts of the aquifer. Furthermore, the conductive fracture zones are conduits which connect the shallow glacifluvial aquifer system to deep groundwater in the bedrock. Understanding bedrock structures and buried topography is critical for successful groundwater modelling in crystalline, fractured bedrock.

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Geochemistry, U-Pb geochronology and Sm-Nd data from the Paleoproterozoic Western Finland supersuite – A key component in the coupled Bothnian oroclines

Cited by 17 publications

References 64 publications

The Vaasa Migmatitic Complex (Svecofennian Orogen, Finland): Buildup of a LP‐HT Dome During Nuna Assembly

The Vaasa Migmatitic Complex (Svecofennian Orogen, Finland): Buildup of a LP‐HT Dome During Nuna Assembly

Geochemical and U-Pb and Sm-Nd isotopic constraints on the evolution of the Paleoproterozoic Ylitornio nappe complex, northern Fennoscandia

Contribution of bedrock structures to the bedrock surface topography and groundwater flow systems within deep glaciofluvial aquifers in Kurikka, Western Finland

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