Deformed and metamorphosed quartz-rich sandstones in southern Finland and east-central Sweden wer... more Deformed and metamorphosed quartz-rich sandstones in southern Finland and east-central Sweden were presumed to be deposited in late Svecofennian time (30 Ma between the volcanism and sand depositio ...
Highly deformed and metamorphosed Zn-Cu deposits in the Vihanti-Pyhasalmi district of central Fin... more Highly deformed and metamorphosed Zn-Cu deposits in the Vihanti-Pyhasalmi district of central Finland preserve the geochemical signature of pre-metamorphic seafloor alteration and are thus considered as volcanogenic massive sulphide (VMS) deposits. The distribution and chemistry of alteration associated with several deposits (Kangasjarvi, Ruostesuo) constrains an overall stratigraphic-hydrothermal framework. Massive sulphide deposits are hosted by chlorite-sericite altered rhyolites (biotite-garnet-orthoamphibole assemblages) associated with ca. 1.93-1.91 Ga bimodal volcanic sequences. On the mine-scale, alteration of these rocks is contiguous with chloritic stockwork zones (orthoamphibole-cordierite assemblages; depleted δ18O values) developed in adjacent mafic volcanic rocks which define hydrothermal upflow zones within the stratigraphic footwall. Local epidotization and metal leaching of basal basalts and andesites suggests that these rocks were located within high-temperature (&...
Based on an integrated study of geological and geophysical data, a tectonic model for the Palaeop... more Based on an integrated study of geological and geophysical data, a tectonic model for the Palaeoproterozoic evolution of the Svecofennian orogen within the Fennoscandian Shield at the northwestern corner of the East European Craton is proposed. The Svecofennian orogen is suggested to have formed during five, partly overlapping, orogenies: Lapland-Savo, Lapland-Kola, Fennian, Nordic and Svecobaltic. The Svecofennian orogen evolved in four major stages, involving microcontinent accretion (1.92-1.88 Ga), large-scale extension of the accreted crust (1.87-1.84 Ga), continent-continent collision (1.87-1.79 Ga) and finally gravitational collapse (1.79 and 1.77 Ga). The stages partly overlapped in time and space, as different processes operated simultaneously in different parts of the plates. In the Lapland-Savo and Fennian orogenies, microcontinents (suspect terranes) and island arcs were accreted to the Karelian microcontinent, which itself was accreting to Laurentia in the Lapland-Kola o...
The Paleoproterozoic cover sequence at the 100150km wide western margin of the Archean Karelian ... more The Paleoproterozoic cover sequence at the 100150km wide western margin of the Archean Karelian Province is dominated by deep water Lower and Upper Kaleva metasediments. We present here an interpretation of SmNd isotope and geochemical ...
Geological Society, London, Special Publications, 2009
Accretionary processes contributed to major continental growth in Fennoscandia during the Palaeop... more Accretionary processes contributed to major continental growth in Fennoscandia during the Palaeoproterozoic, mainly from 2.1 to 1.8 Ga. The composite Svecofennian orogen covers c. 1×106 km2 and comprises the Lapland–Savo, Fennia, Svecobaltic and Nordic orogens. It is a collage of 2.1–2.0 Ga microcontinents and 2.02–1.82 Ga island arcs attached to the Archaean Karelian craton between 1.92 and 1.79 Ga. Andean-type vertical magmatic additions, especially at c. 1.89 and c. 1.8 Ga, were also important in the continental growth. The Palaeoproterozoic crust is the end product of accretionary growth, continental collision and orogenic collapse. Preserved accretional sections are found in areas where docking of rigid blocks has prevented further shortening. The Pirkanmaa belt represents a composite accretionary prism, and other preserved palaeosubduction zones are identified in the Gulf of Bothnia and the Baltic Sea areas. In the southern segment of the Lapland–Savo orogen collision between ...
... Allekirjoitus/nimen selvennys Tero Niiranen Vesa Nykänen Allekirjoitus/nimen selvennys IlkkaL... more ... Allekirjoitus/nimen selvennys Tero Niiranen Vesa Nykänen Allekirjoitus/nimen selvennys IlkkaLahti Tuomo Karinen Page 4. ... The initial interpretation of FIRE 4A and B lines are presented in Patison et al. (2006) cov-ering the whole of the 80 km depth of the reflection sections. ...
... by Raimo Lahtinen*, Pentti Hölttä, Asko Kontinen, Tero Niiranen, Mikko Nironen, Kerstin Saalm... more ... by Raimo Lahtinen*, Pentti Hölttä, Asko Kontinen, Tero Niiranen, Mikko Nironen, Kerstin Saalmann and Peter Sorjonen-Ward ... Ga arc magmatism in Kola, 1.95 Ga supracrustal rocks and granitoids south of Skellefte, and the 1.931.92 Ga island arc rocks in the Savo belt (Figures ...
Detrital zircon U–Pb SIMS data on quartz-rich metasandstone units presumed to belong to the upper... more Detrital zircon U–Pb SIMS data on quartz-rich metasandstone units presumed to belong to the upper part of the Svecofennian stratigraphy in southeastern Finland and east-central Sweden suggest the existence of clastic sedimentary basins between the two main orogenic phases at 1.89–1.86Ga and 1.83–1.79Ga, during a period referred to as the intra-orogenic phase (1.86–1.83Ga).Stratigraphically below the metasandstone at Hamrånge, east-central Sweden,
The Fennoscandian Shield, a part of the East European Craton, is mainly composed of Archean and P... more The Fennoscandian Shield, a part of the East European Craton, is mainly composed of Archean and Paleoproterozoic crust. The Paleoproterozoic tectonic evolution of the Archean Karelian craton, nucleus for the Fennoscandian Shield, exemplified a long period of rifting between 2.5 and 2.1 Ga leading finally to a continental break-up at 2.06 Ga. We reject the concept of a semi-continuous Svecokarelian/Svecofennian orogeny for the accretion of Paleoproterozoic crust in this nucleus and define five orogenies for the time period 1.92-1.79 Ga instead. The Lapland-Kola, Lapland-Savo, Svecofennian, Svecobaltic and Nordic orogenies overlap partly in time and space, and have different structural grains. This multiple orogenic evolution is divided into a microcontinent accretion stage (1.92-1.88 Ga), large-scale extension of the accreted crust (1.87-1.84 Ga) and a continent-continent collision stage (1.87-1.79 Ga). Orogenic collapse and the stabilization of the Fennoscandian between 1.79 and 1.7...
Deformed and metamorphosed quartz-rich sandstones in southern Finland and east-central Sweden wer... more Deformed and metamorphosed quartz-rich sandstones in southern Finland and east-central Sweden were presumed to be deposited in late Svecofennian time (30 Ma between the volcanism and sand depositio ...
Highly deformed and metamorphosed Zn-Cu deposits in the Vihanti-Pyhasalmi district of central Fin... more Highly deformed and metamorphosed Zn-Cu deposits in the Vihanti-Pyhasalmi district of central Finland preserve the geochemical signature of pre-metamorphic seafloor alteration and are thus considered as volcanogenic massive sulphide (VMS) deposits. The distribution and chemistry of alteration associated with several deposits (Kangasjarvi, Ruostesuo) constrains an overall stratigraphic-hydrothermal framework. Massive sulphide deposits are hosted by chlorite-sericite altered rhyolites (biotite-garnet-orthoamphibole assemblages) associated with ca. 1.93-1.91 Ga bimodal volcanic sequences. On the mine-scale, alteration of these rocks is contiguous with chloritic stockwork zones (orthoamphibole-cordierite assemblages; depleted δ18O values) developed in adjacent mafic volcanic rocks which define hydrothermal upflow zones within the stratigraphic footwall. Local epidotization and metal leaching of basal basalts and andesites suggests that these rocks were located within high-temperature (&...
Based on an integrated study of geological and geophysical data, a tectonic model for the Palaeop... more Based on an integrated study of geological and geophysical data, a tectonic model for the Palaeoproterozoic evolution of the Svecofennian orogen within the Fennoscandian Shield at the northwestern corner of the East European Craton is proposed. The Svecofennian orogen is suggested to have formed during five, partly overlapping, orogenies: Lapland-Savo, Lapland-Kola, Fennian, Nordic and Svecobaltic. The Svecofennian orogen evolved in four major stages, involving microcontinent accretion (1.92-1.88 Ga), large-scale extension of the accreted crust (1.87-1.84 Ga), continent-continent collision (1.87-1.79 Ga) and finally gravitational collapse (1.79 and 1.77 Ga). The stages partly overlapped in time and space, as different processes operated simultaneously in different parts of the plates. In the Lapland-Savo and Fennian orogenies, microcontinents (suspect terranes) and island arcs were accreted to the Karelian microcontinent, which itself was accreting to Laurentia in the Lapland-Kola o...
The Paleoproterozoic cover sequence at the 100150km wide western margin of the Archean Karelian ... more The Paleoproterozoic cover sequence at the 100150km wide western margin of the Archean Karelian Province is dominated by deep water Lower and Upper Kaleva metasediments. We present here an interpretation of SmNd isotope and geochemical ...
Geological Society, London, Special Publications, 2009
Accretionary processes contributed to major continental growth in Fennoscandia during the Palaeop... more Accretionary processes contributed to major continental growth in Fennoscandia during the Palaeoproterozoic, mainly from 2.1 to 1.8 Ga. The composite Svecofennian orogen covers c. 1×106 km2 and comprises the Lapland–Savo, Fennia, Svecobaltic and Nordic orogens. It is a collage of 2.1–2.0 Ga microcontinents and 2.02–1.82 Ga island arcs attached to the Archaean Karelian craton between 1.92 and 1.79 Ga. Andean-type vertical magmatic additions, especially at c. 1.89 and c. 1.8 Ga, were also important in the continental growth. The Palaeoproterozoic crust is the end product of accretionary growth, continental collision and orogenic collapse. Preserved accretional sections are found in areas where docking of rigid blocks has prevented further shortening. The Pirkanmaa belt represents a composite accretionary prism, and other preserved palaeosubduction zones are identified in the Gulf of Bothnia and the Baltic Sea areas. In the southern segment of the Lapland–Savo orogen collision between ...
... Allekirjoitus/nimen selvennys Tero Niiranen Vesa Nykänen Allekirjoitus/nimen selvennys IlkkaL... more ... Allekirjoitus/nimen selvennys Tero Niiranen Vesa Nykänen Allekirjoitus/nimen selvennys IlkkaLahti Tuomo Karinen Page 4. ... The initial interpretation of FIRE 4A and B lines are presented in Patison et al. (2006) cov-ering the whole of the 80 km depth of the reflection sections. ...
... by Raimo Lahtinen*, Pentti Hölttä, Asko Kontinen, Tero Niiranen, Mikko Nironen, Kerstin Saalm... more ... by Raimo Lahtinen*, Pentti Hölttä, Asko Kontinen, Tero Niiranen, Mikko Nironen, Kerstin Saalmann and Peter Sorjonen-Ward ... Ga arc magmatism in Kola, 1.95 Ga supracrustal rocks and granitoids south of Skellefte, and the 1.931.92 Ga island arc rocks in the Savo belt (Figures ...
Detrital zircon U–Pb SIMS data on quartz-rich metasandstone units presumed to belong to the upper... more Detrital zircon U–Pb SIMS data on quartz-rich metasandstone units presumed to belong to the upper part of the Svecofennian stratigraphy in southeastern Finland and east-central Sweden suggest the existence of clastic sedimentary basins between the two main orogenic phases at 1.89–1.86Ga and 1.83–1.79Ga, during a period referred to as the intra-orogenic phase (1.86–1.83Ga).Stratigraphically below the metasandstone at Hamrånge, east-central Sweden,
The Fennoscandian Shield, a part of the East European Craton, is mainly composed of Archean and P... more The Fennoscandian Shield, a part of the East European Craton, is mainly composed of Archean and Paleoproterozoic crust. The Paleoproterozoic tectonic evolution of the Archean Karelian craton, nucleus for the Fennoscandian Shield, exemplified a long period of rifting between 2.5 and 2.1 Ga leading finally to a continental break-up at 2.06 Ga. We reject the concept of a semi-continuous Svecokarelian/Svecofennian orogeny for the accretion of Paleoproterozoic crust in this nucleus and define five orogenies for the time period 1.92-1.79 Ga instead. The Lapland-Kola, Lapland-Savo, Svecofennian, Svecobaltic and Nordic orogenies overlap partly in time and space, and have different structural grains. This multiple orogenic evolution is divided into a microcontinent accretion stage (1.92-1.88 Ga), large-scale extension of the accreted crust (1.87-1.84 Ga) and a continent-continent collision stage (1.87-1.79 Ga). Orogenic collapse and the stabilization of the Fennoscandian between 1.79 and 1.7...
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Papers by Raimo Lahtinen