Prograde metamorphism of metapelites, garnet-biotite thermometry and prograde changes of biotite chemistry in high-grade rocks of West Uusimaa, southwest Finland

Schreurs, J. W. H.

doi:10.1016/0024-4937(85)90011-8

Cited by 48 publications

(38 citation statements)

References 10 publications

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“…Evidence for retrograde exchange of this kind, resulting from a temperature-dependent change in the Mn-(Mg, Fe) and Mg-Fe distribution coefficients (garnetbiotite) was presented by Hess (1971), Grant & Weiblen (1971), Tracy et al (1976), Schreurs (1985), Florence & Spear (1995) and others.…”

Section: Microcompositionmentioning

confidence: 99%

Shape, size, spatial distribution and composition of garnet crystals in highly deformed gneiss of the Otter Lake area, Québec, and a model for garnet crystallization

Kretz¹

2006

Journal Metamorphic Geology

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Garnet-biotite-(sillimanite) gneiss ($700°C, 7 kbar) of the Otter Lake area in the Western Grenville Province (Canadian Shield) occurs as granitic gneiss (group 4) that forms a large part of the Otter Complex, and as widely distributed, more heterogenous metasedimentary gneiss (group 2). In one sample of group 4 gneiss (Qtz 25 Pl 34 Kfs 28 Bt 10 Grt 2.5 Sil 1 ) the true diameter (determined by serial grinding) of subhedral garnet crystals ranges from 0.2 to 3.0 mm, with a mode at 1.0 mm. Nearestneighbour measurements in this sample, and in surfaces of nine additional samples (all <5% garnet) confirm that garnet crystals are distributed mainly at random; slight clustering was detected in two samples. In one sample of group 4 gneiss, microprobe analyses on sections through crystal centres (obtained by serial slicing), reveal that small crystals and margins to large crystals contain more Fe and Mn and less Mg than the broad central regions of large crystals. Based on these and previous results, together with theoretical considerations, a crystallization model is proposed, in which, (i) garnet was produced by the continuous reaction, Ms + Bt + Qtz fi Grt + Kfs + H 2 O, (ii) nucleation occurred by the random selection of randomly distributed Ms-Bt-Qtz triple junctions, (iii) the rate of linear growth remained constant, and (iv) as temperature increased, the rate of nucleation first increased slowly, then remained nearly constant, and finally declined. Within-population compositional homogenization was followed, on cooling, by local Fe-Mg-Mn exchange with biotite.

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Section: Microcompositionmentioning

confidence: 99%

Shape, size, spatial distribution and composition of garnet crystals in highly deformed gneiss of the Otter Lake area, Québec, and a model for garnet crystallization

Kretz¹

2006

Journal Metamorphic Geology

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“…(e.g., Bohlen & Essene, 1980;Indares & Martignole, 1985a;Schreurs, 1985;Chipera & Perkins, 1988;Edwards & Essene, 1988;Young et al, 1989). Values obtained with the model of Hodges & Spear (1982) are similar to those obtained with the model of Ferry & Spear (1978), whereas the calibration of Indares & Martignole (1985b) gives lower temperatures.…”

Section: Garnet-biotitementioning

confidence: 74%

“…Biotites Biotites in high-grade rocks have been shown to exchange Mg and Fe with garnets during cooling, which affects garnet-biotite thermometry (e.g., Indares & Martignole, 1985a;Schreurs, 1985;Edwards & Essene, 1988). The Mg/Fe exchange with garnet may cause biotites touching garnets to have compositions different from those of matrix biotites; matrix biotites near garnets may have compositions different from those of distant biotites.…”

Section: Garnetsmentioning

confidence: 99%

Thermobarometry, Geochronology and the Interpretation of P-T-t Data in the Britt Domain, Ontario Grenville Orogen, Canada

Tuccillo¹,

Mezger

Essene³

et al. 1992

Journal of Petrology

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Textural evidence, thermobarometry, and geochronology were used to constrain the pressuretemperature-time (P-T-t) history of the southern portion of the Britt domain in the Central Gneiss Belt, Ontario Grenville Province. Typical metapelitic assemblages are quartz + plagioclase+ biotite + garnet + kyanite ± alkali feldspar ± sillimanite ± rutile ± ilmenite ± staurolite ± gahnite ± muscovite. Metatonalitic assemblages have quartz + plagioclase + garnet + biotite + hornblende + rutile + ilmenite. Metagabbroic rocks contain plagioclase + garnet + clinopyroxene + biotite + ilmenite ± hornblende ± rutile± quartz. Notable textural features include overgrowths of sillimanite on kyanite and of spinel on staurolite. The spinel overgrowths can be modeled by the breakdown of staurolite via the reaction Fe-staurolite = hercynite +kyanite + quartz+ H 2 O. The decomposition of staurolite to hercynite has a steep dP/dT slope and constrains the late prograde path of a staurolite metapelite. Garnet-Al 2 SiOj-plagioclase-quartz (GASP) barometry applied to metapelitic garnets that preserve calcium zoning reveals a pressure decrease from ~ 11 to 6 kb at an assumed temperature of 700 °C. Garnet-plagioclase-ilmenite-rutile-quartz and garnet-clinopyroxene-plagioclase-quartz barometry is in good agreement with pressures obtained with the GASP barometer. Geochronologic data from garnet, allanite, and monazite in metapelitic rocks give ages that fall into two groups, ~ 1-4 Ga and 1 • 1 Ga, suggesting the presence of at least two metamorphic events in the area. It is most reasonable to assign the 1-4 Ga age to the high-pressure data and the 1-1 Ga age to the lower-pressure data. Collectively the P-T-t data indicate a complex and protracted history rather than a single cycle of burial and uplift for this part of the Grenville Province.

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“…Mouri et al (2005) estimated 750-800° C and 4-5 kbar conditions in the West Uusimaa Complex during peak of the late Svecofennian metamorphism (1.83-1.81 Ga). According to Schreurs (1985), the increase in metamorphic grade and development of the West Uusimaa Complex was a thermal, virtually isobaric event, and therefore suggested that the whole region, including the Orijärvi area, represents one crustal level. However, Skyttä et al (2006) noted an abrupt change in metamorphic grade across the Jyly shear zone and interpreted that the Jyly and Kisko shear zones acted as block margins during the late Svecofennian period, with reverse (east-side-up) dip-slip movement in the Jyly shear zone.…”

Section: Geological Settingmentioning

confidence: 99%

“…1). In the 1970's and 1980's the research projects by the Free University of Amsterdam led to a series of papers on metamorphism (Schreurs, 1984;Schreurs, 1985;Blom, 1988) and structures (Bleeker and Westra, 1987;Ploegsma and Westra, 1990;Ploegsma, 1991) in the central Uusimaa belt. Ploegsma and Westra (1990) called the triangular area bordered by Kisko and Jyly shear zones the Orijärvi triangle.…”

Section: Introductionmentioning

confidence: 99%

The Salittu Formation in southwestern Finland, part I: Structure, age and stratigraphy

Nironen¹,

Mänttäri²,

Väisänen³

2016

Bull Geol Soc Finland

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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 picriticbasaltic metavolcanic rocks of the Salittu Formation, located in the northeastern part of the Orijärvi area, has been characterized but otherwise the bedrock and structures have been barely touched. After remapping we give an interpretation of structural evolution, provide new age data to constrain duration of volcanism at Salittu, and refine the stratigraphy in the Orijärvi area.The original stratigraphy is visible at Salittu: metabasalt overlies migmatitic gneisses, and metapicrite is on top. The rocks were folded during early Svecofennian D 1 -D 2 deformations, and the large synformal structures developed as D 2 -D 5 interference structures formed during late Svecofennian D 5 deformation. The structural pattern at Salittu is much the same as in the Orijärvi triangle.The new age data, combined with earlier published data, constrains the Salittu volcanism at ca. 1875 Ma. The stratigraphy in the Orijärvi area consists of the early (1.90-1.89 Ga) volcanic Orijärvi Formation, overlain by the sedimentary Vetio Formation, the volcanic Kisko Formation, the volcanic-sedimentary Ahdisto Formation, the volcanic Toija Formation, and on top the Salittu Formation, all emplaced at 1.88-1.87 Ga. We propose a model in which the Orijärvi Formation represents magmatism at the margin of a microcontinent, and the overlying package represents sedimentation and magmatism above a subduction zone during an initial stage of microcontinental accretion. D 1 deformation occurred in an advanced stage of accretion, after emplacement of the volcanic rocks of the Salittu Formation.

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Prograde metamorphism of metapelites, garnet-biotite thermometry and prograde changes of biotite chemistry in high-grade rocks of West Uusimaa, southwest Finland

Cited by 48 publications

References 10 publications

Shape, size, spatial distribution and composition of garnet crystals in highly deformed gneiss of the Otter Lake area, Québec, and a model for garnet crystallization

Shape, size, spatial distribution and composition of garnet crystals in highly deformed gneiss of the Otter Lake area, Québec, and a model for garnet crystallization

Thermobarometry, Geochronology and the Interpretation of P-T-t Data in the Britt Domain, Ontario Grenville Orogen, Canada

The Salittu Formation in southwestern Finland, part I: Structure, age and stratigraphy

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