A comparison of microstructural and chemical patterns in garnet from the Fleur de Lys Supergroup, Newfoundland

Stallard, Aaron; Hickey, Kenneth A.

doi:10.1016/s0191-8141(01)00095-5

Cited by 23 publications

(7 citation statements)

References 27 publications

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“…We propose that Type I zircon grew at 465 ± 12 Ma on the M 1 retrograde path during garnet break down following eclogite-facies metamorphism. This is consistent with the interpretation of Stallard and Hickey (2002) that the first stage of garnet growth (their G1) in the Fleur de Lys Supergroup ceased and garnet consumption began following the Early Ordovician Taconic metamorphism. The flat HREE patterns of Type II zircon resemble the compositional profiles for zircon that formed either synor post-garnet growth.…”

Section: U-pb Age and Trace Element Geochemistrysupporting

confidence: 79%

“…These low U zircon grains and narrow overgrowths could not be dated. We tentatively interpret that they crystallized during Salinic M 2 metamorphism when growth of new garnet phases resumed (analogous to the G2 to G4 garnet growth phases of Stallard and Hickey 2002) under amphibolite-facies conditions. (Cawood et al 1994) despite the structural, petrological and sedimentological evidence for Ordovician Taconic tectonism (e.g.…”

Section: U-pb Age and Trace Element Geochemistrymentioning

confidence: 99%

“…Regionally, rocks of the Fleur de Lys Supergroup are characterized by the growth of late M 2 albite and garnet (± biotite, chloritoid, kyanite, staurolite and pyroxene) porphyroblasts (Hibbard 1983;Jamieson and Vernon 1987;Jamieson and O'Beirne-Ryan 1991;Stallard 1998;Stallard and Hickey 2002). Porphyroblasts have been interpreted to have formed during a phase of decompression and heating at ca.…”

Section: Tectonometamorphic Evolutionmentioning

confidence: 99%

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Taconic Metamorphism Preserved in the Baie Verte Peninsula, Newfoundland Appalachians: Geochronological Evidence for Ophiolite Obduction and Subduction and Exhumation of the Leading Edge of the Laurentian (Humber) Margin During Closure of the Taconic Seaway

Castonguay

Staal

Joyce

et al. 2014

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The Baie Verte Peninsula, western Newfoundland Appalachians, preserves evidence for Early to Mid Ordovician closure of the Taconic seaway, which led to obduction of the Baie Verte oceanic tract (BVOT) ophiolites onto the Laurentian (Humber) margin and Taconic orogenesis. The scarcity of Taconic radiometric ages (and predominance of Silurian (Salinic) data) from the Humber margin rocks (down-going plate) has been problematic, calling into question the intensity and existence of Taconic collisional orogenesis. 40Ar/39Ar and in situ U–Pb geochronology was undertaken on metamorphosed units from the Laurentian basement (Mesoproterozoic East Pond Metamorphic Suite), from the ca. 560 Ma Birchy Complex forming the leading edge of the Humber margin, and from the ca. 490 Ma ophiolitic rocks of the BVOT (Advocate Complex) in order to address this question. Our results confirm evidence of Taconic metamorphism along the Humber margin and at the base of the ophiolites. Ages obtained from the structural base of the Advocate Complex (481–465 Ma) are interpreted to reflect the timing of accretion and internal thickening of the ophiolite, whereas data from the underlying Birchy Complex (467–461 Ma) record the underthrusting and exhumation of the leading edge of the Humber margin along a subduction channel, penecontemporaneously with final obduction of the BVOT. A concordant ca. 465 Ma zircon age and REE data obtained from retrogressed eclogite of the East Pond Metamorphic Suite suggest that the parautochthonous Humber margin was locally subducted to eclogite-facies conditions during the Taconic collision and partly exhumed to amphibolite-facies conditions prior to a strong Silurian (Salinic) tectonometamorphic overprint.SOMMAIRELa péninsule de Baie Verte dans les Appalaches de l’ouest de Terre-Neuve a conservé des indices de la fermeture du bras de mer taconique, qui a mené à l’obduction des ophiolites de la bande océanique de Baie Verte (BOBV) sur la marge laurentienne (Humber) et à l’orogénèse taconique. La rareté des âges radiométriques taconiques (et la prédominance des données siluriennes (saliniques)) provenant des roches de la marge de Humber (i.e. la plaque subductée) a été problématique, mettant en question l’intensité et l’existence de la collision orogénique taconique. De la géochronologie 40Ar/39Ar et U–Pb in situ a été réalisée sur des unités métamorphisés provenant du socle laurentien (la Suite Métamorphique d’East Pond d’âge Mésoprotérozoïque), du Complexe de Birchy daté à ca. 560 Ma formant la partie frontale de la marge de Humber, and des roches ophiolitiques de la BOBV (Complexe d’Advocate) datée à ca. 490 Ma afin de confronter ce questionnement. Nos résultats confirment les indices de métamorphisme taconique le long de la marge de Humber et à la base des ophiolites. Les âges obtenus à la base structurale du Complexe d’Advocate (481–465 Ma) sont interprétés comme reflétant la période d’accrétion et d’épaississement interne de l’ophiolite, tandis que les données du Complexe de Birchy sous-jacent (467–461 Ma) enregistrent le sous-charriage et l’exhumation de la partie frontale de la marge de Humber au sein d’un chenal de subduction, de façon pénécontemporaine à l’obduction finale de la BOBV. Un âge concordant de ca. 465 Ma d’un zircon et les données de terres rares provenant d’une éclogite rétromorphosée de la suite métamorphique d’East Pond suggèrent que la marge de Humber parautochtone a été localement subductée à des conditions du faciès éclogitique durant la collision taconique et partiellement exhumée à des conditions du faciès des amphibolites précédant la forte surimposition tectonométamorphique silurienne (salinique).

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Section: U-pb Age and Trace Element Geochemistrysupporting

confidence: 79%

Section: U-pb Age and Trace Element Geochemistrymentioning

confidence: 99%

Section: Tectonometamorphic Evolutionmentioning

confidence: 99%

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Taconic Metamorphism Preserved in the Baie Verte Peninsula, Newfoundland Appalachians: Geochronological Evidence for Ophiolite Obduction and Subduction and Exhumation of the Leading Edge of the Laurentian (Humber) Margin During Closure of the Taconic Seaway

Castonguay

Staal

Joyce

et al. 2014

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“…Garnet porphyroblasts in metamorphic rocks provide valuable information on the processes of crystal nucleation and growth for two reasons (Miyashita, 1996): (1) they usually contain internal textural zones and inclusion trails that aid in correlating the timing of garnet growth under specific conditions with deformation and metamorphism (e.g., Hollister, 1966;Andersen, 1984;Rice and Mitchell, 1991;Williams, 1994;Bell et al, 1997;Stallard and Hickey, 2002;Meth and Carlson, 2005;Kim and Jung, 2010;Kiers, 2013), and (2) they have distinct chemical zoning retaining a record of their growth history (e.g., Olimpio and Anderson, 1978;Takasu, 1986;Stallard and Hickey, 2002;Meth and Carlson, 2005;Stowell et al, 2011) and showing some of the greatest variability in terms of solid solution, providing data to constrain the P-T-t evolution of metamorphism in orogenic belts (e.g., Florence and Spear, 1993;Ratner and Cheney, 2002).…”

Section: Introductionmentioning

confidence: 99%

Occurrence and growth history of texturally sector- and sigmoidal-zoned garnet in the San Lo renzo Schists in the Sierra Nevada de Santa Marta massif (Co lombia)

2016

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“…Spear & Daniel, 2001; Yang & Rivers, 2001; Ikeda et al. , 2002; Stallard & Hickey, 2002). Thus, zoning patterns of major and trace elements in garnet allow us to understand transport processes during the growth of garnet, although the transport of aluminium is generally regarded as the rate‐limiting factor in garnet crystallization because of slow diffusion rate and low solubility in metamorphic fluid (Anderson et al.…”

Section: Introductionmentioning

confidence: 99%

Two‐stage growth of porphyroblastic biotite and garnet in the Barrovian metapelites of the Imjingang belt, central Korea

Kim

Cho

2008

Journal Metamorphic Geology

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Porphyroblastic biotite and garnet in the Barrovian metapelites of the Imjingang belt, Korea, were investigated to unravel the sequence and mechanism of mineral growth. Poikiloblastic biotite contains straight inclusion trails (S i ) discontinuous to the major foliation, and develops clear zones at the grain margin. These microstructures suggest an initial growth of biotite between two contractional deformations (D n)1 and D n ) followed by an overgrowth during D n . Although garnet poikiloblasts contain variable S i patterns, their major growth is likely to have occurred during D n on the basis of compositional relationships among variable garnet types. Early poikiloblasts of both minerals were formed by chemical replacement of the matrix that consisted mainly of chlorite, muscovite and quartz. Subsequent growth of biotite was governed by a crack-filling mechanism, and was accompanied by the production of extensional cracks inside or around biotite, providing fluid pathways. The overgrowth of garnet was favoured at the biotite-garnet interface, and the consequence was a partial replacement of inclusion-poor garnet after biotite subsequent to D n . In addition, clear zones and pressure shadows as well as the matrix around biotite porphyroblasts were replaced by garnet, suggesting an inheritance of various pre-existing microstructures in the S i pattern of garnet. Further attention is thus required for any attempt to delineate the microstructural interaction between deformation and metamorphism, particularly in a sample containing early-grown porphyroblasts. Microstructural evidence for the twostage growth of biotite and garnet is present up to the kyanite zone, indicating that this growth mechanism is prevalent during progressive metamorphism of Barrovian metapelites.

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A comparison of microstructural and chemical patterns in garnet from the Fleur de Lys Supergroup, Newfoundland

Cited by 23 publications

References 27 publications

Taconic Metamorphism Preserved in the Baie Verte Peninsula, Newfoundland Appalachians: Geochronological Evidence for Ophiolite Obduction and Subduction and Exhumation of the Leading Edge of the Laurentian (Humber) Margin During Closure of the Taconic Seaway

Taconic Metamorphism Preserved in the Baie Verte Peninsula, Newfoundland Appalachians: Geochronological Evidence for Ophiolite Obduction and Subduction and Exhumation of the Leading Edge of the Laurentian (Humber) Margin During Closure of the Taconic Seaway

Occurrence and growth history of texturally sector- and sigmoidal-zoned garnet in the San Lo renzo Schists in the Sierra Nevada de Santa Marta massif (Co lombia)

Two‐stage growth of porphyroblastic biotite and garnet in the Barrovian metapelites of the Imjingang belt, central Korea

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