Rb–Sr muscovite age of a pegmatite near Sivakkavaara, Finland

Breemen, O. van; Bowes, D. R.

doi:10.17741/bgsf/49.1.002

Cited by 8 publications

(5 citation statements)

References 6 publications

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“…Halden 1982a, b). This is consistent with the evidence of van Breemen and Bowes (1977) that the crustal segment remained at elevated temperatures for a considerable time.…”

Section: Structural Context Of Granitic Materialssupporting

confidence: 92%

“…In the area N of Sivakkavaara (Fig. 3), van Breemen and Bowes (1977) report related pegmatites discordant to F 3 -S 3 , but cut by S 4 and folded by F 4 . Near Rauvantaipale and N of Luikonlahti, the biotite preferred orientation in some granite sheets is parallel to S 4 , and the same is true of the fractures noted in massive granite near Onnivaara.…”

Section: Structural Context Of Granitic Materialsmentioning

confidence: 94%

“…The mass of the Maarianvaara granitoid suite appears to have been emplaced into the cover and basement rocks between D 3 and D 4 , with some pegmatites later than D 4 . The c. 1850 Ma age for post-D 3 , pre-D 4 pegmatites near Sivakkavaara (van Breemen & Bowes 1977; Rb-Sr muscovite recalculated using decay constants of Steiger & Jager 1977) represents the only isotopic data that can be linked to the structural sequence. However, the c. 1800 Ma (U-Pb zircon) age of a member of the Maarianvaara granitoid suite (Kuovo & Tilton 1966) suggests that magmatic activity may have spanned a considerable time range (cf.…”

Section: Structural Context Of Granitic Materialsmentioning

confidence: 99%

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Basement–cover relationships during polyphase deformation in the Svecokarelides of the Kaavi district, eastern Finland

Park

Bowes

1983

Transactions of the Royal Society of Edinburgh: Earth Sciences

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For much of its length in eastern Finland, the contact between the late Archaean granitoid terrane and early Proterozoic supracrustal rocks is that of a depositional unconformity tectonically modified during the Svecokarelian orogeny. In the Kaavi district, this modification has been extensive, particularly because of thrusting which resulted in tectonic slices of basement being present as inliers within the cover rocks and cover rocks as outliers within the main basement outcrop. Both basement and cover have undergone repeated deformation and metamorphic recrystallisation reflected by the presence of multiple tectonic fabrics and sequential mineral growths. However, it is only locally in major zones of movement that the basement rocks of the Presvecokarelides show major modification as the result of the deformation which had such a profound effect on the cover rocks during the development of the Svecokarelides. Over large areas, the products of four phases of deformation (DI–IV) remain in the basement gneisses together with the products of basic and acidic intrusion whose positions in the deformational sequence can be established‥In the cover rocks, early nappe emplacement (Outokumpu nappe) was followed by the development of isoclinal folds associated with prograde metamorphism (D1). Regionally expressed asymmetrical folds, overturned to the E, with attenuation of overturned limbs and thrusting, involving basement, followed (D2). Subsequent deformation related to wrench faulting (D2c) was followed by the development of more open folds associated with declining geotherms (D3, D4); F3–F4 interference structures are expressed as domes, some of which were a locus of granitoid emplacement (Maarianvaara granitoid suite). D5 and D6 are expressed as cleavages and fractures.Correlation of the structural features in the Kaavi district with those in the Outokumpu and adjacent districts forms the basis both for establishing the regional disposition of basement and cover units and for determining the structural evolution of this part of the Svecokarelides.

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“…Halden 1982a, b). This is consistent with the evidence of van Breemen and Bowes (1977) that the crustal segment remained at elevated temperatures for a considerable time.…”

Section: Structural Context Of Granitic Materialssupporting

confidence: 92%

Section: Structural Context Of Granitic Materialsmentioning

confidence: 94%

Section: Structural Context Of Granitic Materialsmentioning

confidence: 99%

See 1 more Smart Citation

Basement–cover relationships during polyphase deformation in the Svecokarelides of the Kaavi district, eastern Finland

Park

Bowes

1983

Transactions of the Royal Society of Edinburgh: Earth Sciences

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“…The intrusion of the Maarianvaara granite during D 3 and D 4 (c.f. van Breemen and Bowes 1977) between Kaavi and Outokumpu may account for this; there is evidence in the same district of granitic material being associated with the end of the D 2 deformational phase (Park 1983 a).…”

Section: Regional Correlation Of Metamorphic Conditionsmentioning

confidence: 94%

Metamorphic development of cordierite-bearing layered schist and mica schist in the vicinity of Savonranta, eastern Finland

Halden¹,

Bowes²

1984

Bull Geol Soc Finland

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., 1984: Metamorphic development ofcordierite-bearing layered schist and mica schist in the vicinity of Savonranta, eastern Finland. Bull. Geol. Soc. Finland 56, Part 1-2, 3-23.The sequential development of minerals in polyphase deformed schists of the Savonranta district can be demonstrated in a limited number of lithologies. Cordierite-bearing and micaceous schists are used to established a polymetamorphic history within an area where field mapping and structural studies have provided a basis for the erection of temporal relations of metamorphic fabric elements. Coexisting phases whose relative times of development have been established were selected for microprobe analysis ana their compositions used in a quantitative thermodynamic study to determine temperatures and pressures of successive metamorphic events.Conditions deduced for the phase of metamorphism (M,) associated with the D. deformational phase are c. 550°C and 3 kb. The peak of metamorphism, during M 2 -D 2 was at c. 700°C and 7.5 kb. Conditions for an M 3 metamorphic event of c. 300°C and 2-3 kb are estimated from mineral assemblages in P-T space, not from mineral compositions. A late thermal event (M L ') is related to the emplacement of porphyritic granite: c. 600°C and 4kb are estimated from mineral assemblages in P-T space.A single outcrop of a layered schist, which is unique to the district, is interpreted as a tectonic slice from a deeper crustal level. It provides evidence of a low P, high T granulite facies metamorphic event (M EARLY ) pre-dating M,-D,.

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“…Post-D 5 deformation includes very open, upright folds and kink-bands (F 6 ) with axial planar fractures (S 6 ) and near N-S axial trend (Bowes 1975(Bowes , 1976avan Breemen & Bowes 1977). In addition vertical or near-vertical healed fractures with N-S traces which have been observed at many outcrops are considered to be expressions of the D 6 deformational phase.…”

Section: Structural Sequencementioning

confidence: 99%

Structural evolution of an early Proterozoic strata-bound Cu-Co-Zn deposit, Outokumpu, Finland

Koistinen

1981

Transactions of the Royal Society of Edinburgh: Earth Sciences

127

132

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The massive pyrite-pyrrhotite-chalcopyrite-sphalerite deposit of Outokumpu, comprising the Keretti and Vuonos orebodies, is a deformed and metamorphosed strata-bound mass associated with mineralised stockworks. Mobilisation of much of the ore followed formation of large recumbent isoclinal folds that are the major structures of the surrounding rocks and associated with the modification of originally flat saucer-shaped ore lenses into elongate ruler-shaped masses. Further modification of shape took place at the mobilisation stage with much of the pyrrhotitic ore, particularly, now occupying the thickest parts of the orebodies in the form of breccia or microbreccia. In many parts gross original characters still exist and the pyritic and pyrrhotitic constituents of the ore have survived as separate entities while locally the pyritic ore retains pre-deformational characteristics and consistent stratigraphic position within a thin horizon.Both ore and country rocks show evidence of extensive polyphase deformation with the effects of six fold phases shown in the ore. Mineral assemblages in the country rocks indicate a middle amphibolite facies peak of metamorphism. The serpentinite-black schist-carbonate-quartzite rock assemblage, with which the ore is associated, was tectonically incorporated within the regionally extensive mica schist by even earlier subhorizontal thrusting. This is related to the movement of a thrust nappe with the interdigitation of an ocean-floor ophiolite assemblage and flysch deposited during ocean closure associated with Svecokarelian tectonism.The original formation of the Keretti and Vuonos sulphide masses took place in a marine exhalative environment with a pyritic layer overlying a pyrrhotitic layer in each of the two c. 4 km diameter irregularly oval-shaped depressions whose centres were c. 8 km apart. The mineralised stockwork below each mass represents the upper parts of the conduit for metalbearing fluids in a convective system.

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Rb–Sr muscovite age of a pegmatite near Sivakkavaara, Finland

Cited by 8 publications

References 6 publications

Basement–cover relationships during polyphase deformation in the Svecokarelides of the Kaavi district, eastern Finland

Basement–cover relationships during polyphase deformation in the Svecokarelides of the Kaavi district, eastern Finland

Metamorphic development of cordierite-bearing layered schist and mica schist in the vicinity of Savonranta, eastern Finland

Structural evolution of an early Proterozoic strata-bound Cu-Co-Zn deposit, Outokumpu, Finland

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