Loss of metals from pelites during regional metamorphism

Haack, U.; Heinrichs, Hartmut; Boneß, M.; Schneider, Alfred

doi:10.1007/bf00371702

Cited by 78 publications

(17 citation statements)

References 43 publications

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“…Shaw (1954) has shown that most studied elements, with the exception of Na, Ca, Ni, Cu, Pb and Li, remain constant during metamorphism. Similar results have been obtained by Rösler & Beuge (1983) and Haack et al (1984). Other authors have demonstrated a large-scale fluid flow and significant mass transfer during prograde metamorphism (e.g.…”

Section: Introductionsupporting

confidence: 89%

The Erzgebirge, Germany, a subducted part of northern Gondwana: geochemical evidence for repetition of early Palaeozoic metasedimentary sequences in metamorphic thrust units

Mingram

1998

Geol. Mag.

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Originally published as: Mingram, B. (1998): The Erzgebirge, Germany, a subducted part of northern Gondwana: geochemical evidence for repetition of early Palaeozoic metasedimentary sequences in metamorphic thrust units. 135,[785][786][787][788][789][790][791][792][793][794][795][796][797][798][799][800][801] DOI: 10.1017/S0016756898001769 IntroductionThe European Variscan Belt is a collision orogen formed during the late Palaeozoic, and is marked by thrusts and nappes (Matte, 1991). Polymetamorphic crystalline nappes with high-pressure, high-temperature relics of eclogites and granulites are widespread from Poland to Spain, and reflect intracontinental and oceanic subduction zones.The early Palaeozoic history of the Central European Variscides is characterized by crustal extension and development of oceanic basins produced by separation of microplates (e.g. Avalonia, Armorica, and Baltica) from the northern periphery of the Neoproterozoic (Cadomian) supercontinent Gondwana (Matte, 1991;Franke, 1989;Pin, 1990). Bimodal metavolcanic and mafic-ultramafic complexes provide good evidence for extensional rifting regimes in late Cambrian to early Ordovician times (e.g. Pin, 1990;Pin & Marini, 1993;Winchester et al. 1995;Floyd et al. 1996). The boundary between Proterozoic and the early Palaeozoic times marks an unconformity and/or conformity between crystalline and sedimentary formations of the Cadomian basement and highly mature neritic clastic shelf sediments, which pass into hemipelagic shales during the late Ordovician period (Noblet & Lefort, 1990). These changes reflect the development from an orogenic belt to a passive margin setting with associated widespread shallow marine facies. This development is related to the transition from a Neoproterozoic ensialic arc, the Avalonian-Cadomian orogenic belt, to an early Palaeozoic stable platform at the periphery of a Neoproterozoic supercontinent (Nance & Murphy, 1994).Similarities in Palaeozoic depositional settings exist along the major Variscides (Erdtmann, 1991): highmature fine-grained sandstones in the early to middle Arenigian time (Noblet & Lefort, 1990), chamositic oolitic ore horizons in the Arenigian to Ashgillian times (Young, 1989), and an influence of glaciation in the Upper Ordovician and black shale transgressions in the Arenigian, Llanvirnian and Silurian times. However, the paucity of fossils and the strong tectonometamorphic overprint complicate the correlation of sedimentary sequences and the recognition of ancient geodynamic regimes. In addition to conventional structural and petrological studies, the geochemistry of metamorphic rocks has great potential Geol. Mag. 135 (6), 1998, pp. 785-801. Printed Abstract -One of the major metamorphic terranes of the Bohemian Massif, the Erzgebirge, is interpreted to record a subducted part of a Palaeozoic margin of Gondwana. A geochemical study on noncalcareous metasediments from the various metamorphic units from lower greenschist to granulite facies metamorphism supports a recently established thrust mode...

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Section: Introductionsupporting

confidence: 89%

The Erzgebirge, Germany, a subducted part of northern Gondwana: geochemical evidence for repetition of early Palaeozoic metasedimentary sequences in metamorphic thrust units

Mingram

1998

Geol. Mag.

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“…In principle, the concept should also extend to trace element partitioning which should therefore also be useful to estimate P-T conditions during metamorphism (e.g., Heinrich et al, 1997;Bea et al, 1997). In addition to thermobarometry, studies of the partitioning of trace elements among coexisting metamorphic minerals can provide valuable information about equilibrium and petrogenesis (e.g., Haack et al, 1984;Dahl et al, 1993;Hickmott et al, 1987;Hickmott and Spear, 1992;Johnson, 1994;Kretz et al, 1999;Yang et al, 1999). However, the subject has been relatively little investigated because of the difficulty in obtaining uncontaminated trace element analyses and due to complications resulting from crystal chemistry and the composition of host minerals.…”

Section: Introductionmentioning

confidence: 99%

“…At present, there are relatively few published trace element partitioning studies for biotite-muscovite pairs in metamorphic systems (Butler, 1967;Moorbath et al, 1968;Dutrow et al, 1986;Shearer et al, 1986;Hervig and Peacock, 1989;Dahl et al, 1993;Domanik et al, 1993). Moreover, very little is known about the dependence of the biotite/muscovite distribution coefficients on the intensive and extensive variables, constraining geochemists to adopt a largely empirical approach using constant average distribution values in their modeling (e.g., Haack et al, 1984;Johnson, 1994). In addition, most trace element data in the earlier publications were obtained from bulk analyses of mineral separates, which have commonly proved to be contaminated with micro-inclusions of accessory minerals (Michael, 1988).…”

Section: Introductionmentioning

confidence: 99%

Trace element partitioning between coexisting biotite and muscovite from metamorphic rocks, Western Labrador: structural, compositional and thermal controls

Yang

Rivers

2000

Geochimica et Cosmochimica Acta

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Abstract-Coexisting biotite and muscovite in ten metapelitic and quartzofeldspathic rocks from western Labrador have been analyzed by electron microprobe for major and minor elements and by a laser ablation microprobe coupled to ICP-MS (LAM-ICP-MS) for selected trace elements-Li, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Hf and Ta. The samples have experienced a single prograde Grenvillian metamorphism ranging from 490 to 680°C and from 7 to 12 kbar. The trace element compositions of coexisting micas in the metamorphic rocks are used to assess the effects of crystal structure, major element composition and temperature on the partitioning of each element between biotite and muscovite.Overall, trace element distributions are systematic across the range of metamorphic grade and bulk composition, suggesting that chemical equilibrium was approached. Most distribution coefficients (biotite/ muscovite) show good agreement with published data. However, distribution coefficients for Co and Sr are significantly different from previous determinations, probably because of contamination associated with older data obtained by bulk analysis techniques. The sequence of distribution coefficients is governed mainly by the ionic radii and charges of substituting cations compared to the optimum ionic radius of each crystallographic site in the micas. In particular, distribution coefficients exhibit the sequence Cr 3ϩ (0.615 Å) Ͼ V 3ϩ (0.64 Å) Ͼ Sc 3ϩ (0.745 Å) in VI-sites, and Ba 2ϩ (1.61 Å) Ͼ Sr 2ϩ (1.44 Å) and CsThe distributions of Li, Sc, Sr and Ba appear to be thermally sensitive but are also controlled by major element compositions of micas. V and Zr partitioning is dependent on T and may be used to cross-check thermometry calculations where the latter suffer from retrograde re-equilibration and/or high concentrations of Fe 3ϩ . The ranges and dependence of distribution coefficients on major element compositions provide important constraints on the values that can be used in geochemical modeling.

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“…Malgré la constance des valeurs de concentration de quelques éléments chimiques, il est cependant imprudent de parler d'immobilité au sens strict, car tant que les réactions métamorphiques continuent à se produire, il existe toujours un élément chimique qui se trouve disponible pour la mobilité (Haack et al, 1984). Il convient donc de parler d'immobilité relative des éléments chimiques Tableau II-9.…”

Section: Ii-6 Caractéristiques Chimiques Des Métapélites Et Comportemunclassified

“…La biotite a une excellente structure pour accepter les cations larges, et elle est fréquemment ouverte à la diffusion de ces éléments. Le Ba qui est supposé être concentré dans la biotite, peut s'adapter dans les mêmes positions structurales que K2O (Haack et al, 1984). Ceci signifie que tout le Ba libéré par la réaction est plus facilement accommodé dans la biotite nouvellement formée, (Evans, 1964;Oba,1968;Wodzicki,1971), ne paraît pas plausible dans le cas de l'auréole métamorphique d'Oulmès.…”

Section: Les éLéments Tracesunclassified

Developpement des aureoles de contact d oulmes et de ment (Maroc central)

Dahmani¹

1995

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Loss of metals from pelites during regional metamorphism

Cited by 78 publications

References 43 publications

The Erzgebirge, Germany, a subducted part of northern Gondwana: geochemical evidence for repetition of early Palaeozoic metasedimentary sequences in metamorphic thrust units

The Erzgebirge, Germany, a subducted part of northern Gondwana: geochemical evidence for repetition of early Palaeozoic metasedimentary sequences in metamorphic thrust units

Trace element partitioning between coexisting biotite and muscovite from metamorphic rocks, Western Labrador: structural, compositional and thermal controls

Developpement des aureoles de contact d oulmes et de ment (Maroc central)

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