3.1 The Early Palaeoproterozoic of Fennoscandia: Geological and Tectonic Settings

Melezhik, Victor A.; Hanski, Eero

doi:10.1007/978-3-642-29682-6_3

Cited by 9 publications

(6 citation statements)

References 17 publications

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“…Rifting of this continental basement between ca. 2.5 and 2.1 Ga developed crustal-scale, riftparallel fault basins and voluminous tholeiitic mafic magmatism and related sedimentation, producing an approximately NW-aligned large igneous province extending from northern Norway to Russia (Pharaoh and Pearce, 1984;Melezhik and Hanski, 2012;Bingen et al, 2015). In northern Sweden, Archean rocks belong to the Norrbotten Craton, one of three continental nuclei that were rifted during the Rhyacian and later reassembled during the Svecokarelian accretionary-collisional orogenic cycle in the Orosirian (e.g.…”

Section: Regional Geological Settingmentioning

confidence: 99%

Evolution of structures and hydrothermal alteration in a Palaeoproterozoic supracrustal belt: Constraining paired deformation–fluid flow events in an Fe and Cu–Au prospective terrain in northern Sweden

Andersson

Lynch

2020

Solid Earth

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Abstract. An approximately 90 km long Palaeoproterozoic supracrustal belt in the northwestern Norrbotten ore province (northernmost Sweden) was investigated to characterize its structural components, assess hydrothermal alteration–structural geology correlations, and constrain a paired deformation–fluid flow evolution for the belt. New geological mapping of five key areas (Eustiljåkk, Ekströmsberg, Tjårrojåkka, Kaitum West, and Fjällåsen–Allavaara) indicates two major compressional events (D1 and D2) have affected the belt, with each associated with hydrothermal alteration types typical for iron oxide–apatite and iron oxide Cu–Au systems in the region. Early D1 generated a regionally distributed, penetrative S1 foliation and oblique reverse shear zones that show a southwest-block-up sense of shear that formed in response to NE–SW crustal shortening. Peak regional metamorphism at epidote–amphibolite facies broadly overlaps with this D1 event. Based on overprinting relationships, D1 is associated with regional scapolite ± albite, magnetite + amphibole, and late calcite alteration of mafic rock types. These hydrothermal mineral associations linked to D1 structures may form part of a regionally pervasive evolving fluid flow event but are separated in this study by crosscutting relationships. During D2 deformation, folding of S0–S1 structures generated F2 folds with steeply plunging fold axes in low-strain areas. NNW-trending D1 shear zones experienced reverse dip-slip reactivation and strike-slip-dominated movements along steep, E–W-trending D2 shear zones, producing brittle-plastic structures. Hydrothermal alteration linked to D2 structures is a predominantly potassic–ferroan association comprising K-feldspar ± epidote ± quartz ± biotite ± magnetite ± sericite ± sulfides. Locally, syn- or post-tectonic calcite is the main alteration mineral in D2 shear zones that intersect mafic rocks. Our results highlight the importance of combining structural geology with the study of hydrothermal alterations at regional to belt scales to understand the temporal–spatial relationship between mineralized systems. Based on the mapping results and microstructural investigations as well as a review of earlier tectonic models presented for adjacent areas, we suggest a new structural model for this part of the northern Fennoscandian Shield. The new model emphasizes the importance of reactivation of early structures, and the model harmonizes with tectonic models presented by earlier workers based mainly on petrology of the northern Norrbotten area.

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Section: Regional Geological Settingmentioning

confidence: 99%

Evolution of structures and hydrothermal alteration in a Palaeoproterozoic supracrustal belt: Constraining paired deformation–fluid flow events in an Fe and Cu–Au prospective terrain in northern Sweden

Andersson

Lynch

2020

Solid Earth

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“…The Paleoproterozoic rifting of the Archean Kola basement craton produced the NW-SE trending Pechenga-Imandra-Varzuga Volcanic Belt (Melezhik & Hanski, 2012;Mitrofanov et al, 1995), in which intense bimodal magmatism occurred over about 500 Myr (Sharkov & Smolkin, 1997). The Neoproterozoic belt comprises two major structures: the Pechenga and Imandra-Varzuga zones separated by a Neoproterozoic meridional thrust with a horizontal translation of around 100 km.…”

Section: Geological Backgroundmentioning

confidence: 99%

Thermochronology and Exhumation History of the Northeastern Fennoscandian Shield Since 1.9 Ga: Evidence From ⁴⁰Ar/³⁹Ar and Apatite Fission Track Data From the Kola Peninsula

et al. 2019

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Results from thermochronological studies have multiple applications to various problems in tectonics and landform evolution. However, up to now a lack of thermochronological data from the northeastern Fennoscandian Shield has complicated the interpretation of tectonothermal evolution of the region. Here, we use both new and previously published multimineral 40Ar/39Ar data (amphibole, mica, and feldspar) on the various Precambrian magmatic and metamorphic complexes to reconstruct the thermal history of NE Fennoscandia within the Kola Peninsula area in the interval 1900–360 Ma. Using the apatite fission track method as well as a numerical model of the heating‐cooling process of northeastern Fennoscandia's upper crust, we have reconstructed its thermal evolution for the interval 360–0 Ma. According to our model, since Lapland‐Kola orogenesis (1930–1905 Ma) northeastern Fennoscandia experienced a quasi‐monotonous cooling with the average rate of ~0.15 °C/Myr, which is equal to an exhumation rate of ~1–2 m/Myr. New apatite fission track data and time‐temperature modeling reveal a “hidden” endogenous thermal event in the NE Fennoscandia that took place between 360 and 300 Ma. This we attribute to an elevated geothermal gradient due to Baltica's drift over the African large low shear‐wave velocity province in the lowest mantle and/or thermal blanketing by insulating Devonian‐Carboniferous sedimentary/volcanic cover. Our model is further supported by evidence of Late Devonian‐Carboniferous rifting in the East and South‐Western Barents Basin, as well as various 360–300 Ma magmatic events within SW Fennoscandia and the Baltic countries.

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“…The principal stages of the development of the NE part of the Fennoscandian Shield in the Archean and Paleoproterozoic, and the correlating stages of the formation of gold mineralization, are shown in Table 2. The succession of geodynamic events is compiled in accordance with the models presented in [3,4,[75][76][77][78][79]. According to the reconstructions by Mints with coauthors [3], three small continents were formed in the NE part of the Fennoscandian Shield 2.93 Ga ago: those were, from NE to SW in the modern coordinates, the Murmansk, Inari-Kola (or simply Kola), and Khetolambina continents (the latter now is a part of the Belomorian mobile belt).…”

Section: Discussion: the Principal Stages And Conditions Of Formation...mentioning

confidence: 96%

Stages of Gold Deposits Formation in the Precambrian of the North-Eastern Fennoscandia

Kalinin

2022

Minerals

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Two main stages of formation of gold deposits are identified in the north-eastern part of the Fennoscandian Shield—Neoarchean (2.7–2.6 Ga) and Paleoproterozoic (1.92–1.74 Ga). These were the stages of rapid growth of the continental crust of the Earth and the consolidation of the ancient supercontinents, Kenorland in the Neoarchean, and Fennoscandia (or Columbia) in the Paleoproterozoic. Gold deposits and occurrences, which formed in the Archean (Oleninskoe and Nyalm in the Kolmozero–Voron’ya belt, and the Olenegorsk group of BIF deposits) were later metamorphosed in the Paleoproterozoic, and isotope data for the rocks and minerals of these deposits detect both Archean and Paleoproterozoic events. The Paleoproterozoic stage was the most important for the formation of gold deposits in the region, as at this stage the deposits formed not only in the Proterozoic greenstone belts, but in those Archean belts as well, which were involved in the Svecofennian tectonic processes in the Paleoproterozoic. As it is shown in the example of the deposits in the Central Lapland Paleoproterozoic belt, gold mineralization formed with a series of impulses of hydrothermal activity, and these impulses correlate with the formation of different generations of minor granite intrusions and dykes.

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3.1 The Early Palaeoproterozoic of Fennoscandia: Geological and Tectonic Settings

Cited by 9 publications

References 17 publications

Evolution of structures and hydrothermal alteration in a Palaeoproterozoic supracrustal belt: Constraining paired deformation–fluid flow events in an Fe and Cu–Au prospective terrain in northern Sweden

Evolution of structures and hydrothermal alteration in a Palaeoproterozoic supracrustal belt: Constraining paired deformation–fluid flow events in an Fe and Cu–Au prospective terrain in northern Sweden

Thermochronology and Exhumation History of the Northeastern Fennoscandian Shield Since 1.9 Ga: Evidence From ⁴⁰Ar/³⁹Ar and Apatite Fission Track Data From the Kola Peninsula

Stages of Gold Deposits Formation in the Precambrian of the North-Eastern Fennoscandia

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3.1 The Early Palaeoproterozoic of Fennoscandia: Geological and Tectonic Settings

Cited by 9 publications

References 17 publications

Evolution of structures and hydrothermal alteration in a Palaeoproterozoic supracrustal belt: Constraining paired deformation–fluid flow events in an Fe and Cu–Au prospective terrain in northern Sweden

Evolution of structures and hydrothermal alteration in a Palaeoproterozoic supracrustal belt: Constraining paired deformation–fluid flow events in an Fe and Cu–Au prospective terrain in northern Sweden

Thermochronology and Exhumation History of the Northeastern Fennoscandian Shield Since 1.9 Ga: Evidence From 40Ar/39Ar and Apatite Fission Track Data From the Kola Peninsula

Stages of Gold Deposits Formation in the Precambrian of the North-Eastern Fennoscandia

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Thermochronology and Exhumation History of the Northeastern Fennoscandian Shield Since 1.9 Ga: Evidence From ⁴⁰Ar/³⁹Ar and Apatite Fission Track Data From the Kola Peninsula