Hydrothermal mobility of Ti, Zr and REE: examples from the Bergell and Adamello contact aureoles (Italy)

Gieré, Reto

doi:10.1111/j.1365-3121.1990.tb00037.x

Cited by 104 publications

(33 citation statements)

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“…The hydrothermal crystallization of Ti-rich Adr in veins demonstrates there the Ti mobility in aqueous fluids under moderate P-T conditions. Medium-to low-temperature mobility of Ti, Zr and REE in hydrothermal systems was documented by Gieré (1990). Main products of Prv replacement in kimberlite -kassite, anatase, titanite, calcite, ilmenite and a LREE-Ti oxidewere reported by Mitchell and Chakhmouradian (1998).…”

Section: Introductionmentioning

confidence: 96%

The blueschist-associated perovskite-andradite-bearing serpentinized harzburgite from Dobšiná (the Meliata Unit), Slovakia

Putiš¹,

Koppa²,

Snarska³

et al. 2013

J. Geosci.

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Unique, perovskite(Prv)-andradite(Adr)-bearing serpentinized harzburgite fragments occur in Late Jurassic-Early Cretaceous subduction-accretionary wedge complex of the Meliata tectonic Unit (Slovakia, Western Carpathians). These rocks reflect magmatic (E1) and partial melting (E2) mantle events followed by metamorphic blueschist-facies (E3) and fluid-rock interaction (E4) events accompanied by crystallization of Prv and/or Adr. The incompletely solidified slightly depleted (residual) harzburgite composed of early-magmatic assemblage of Ol, Opx 1 , Cr-Spl ± Cpx 1 (E1 event) underwent partial melting (E2 event) under subsolidus mantle conditions. The late-magmatic aggregates of Cpx 2 , Cr-Spl, scarce Opx 2 , due to this batch melting, occur around the Opx 1 (±Cpx 1 ) porphyroclasts. The fractures and cleavage planes of the kinked Opx 1 porphyroclasts are filled by Cpx 3 as a result of subsolidus recrystallization of the Opx 1 . Cloudy lower Al Cpx 4 associated with pargasite in reaction rims between the Opx 1 and Cpx 2 , or antigorite replacing Ol, could represent the E3 high-pressure metamorphic event (dated at 160 to 150 Ma, according to published 40 Ar- 39Ar data for "phengitic" white mica from blueschists) in serpentinites. Serpentinized zones of harzburgite contain Prv, which occurs in serpentinized Opx 1 porphyroclasts. Orthopyroxene (Opx 1 ) breakdown and formation of Prv, (Ti-rich) Adr and chrysotile appears to be postdating the closure of the Meliata back-arc basin (c. 200 to 160 Ma) and HP metamorphism. Perovskite genesis can therefore be bound to the exhumation-related serpentinization in subduction channel and emplacement of serpentinites into subduction-accretionary wedge (E4 event at 300-500 ºC/5-15 kbar, at 150 to 130 Ma?). The bulk-rock trace-element patterns suggest enrichment in LREE, Ba, Cs, U, Pb, Sb and Li in comparison with HREE, HFSE, Rb and Sr. Such element mobility indicates fluid-rock interaction. Pervading aqueous fluids rich in CO 2 were transporting Ca, Ti, Fe, LREE partitioned into Prv grown along the Cpx exsolution lamellae in Opx 1 . The sources of such fluids might have been the blueschist-to greenschist-facies rocks from the Meliata mélange type subduction-accretionary wedge. The late-metamorphic H 2 O-CO 2 /Si-Fe-Mn-rich fluids caused partial replacement of Prv by pyrophanite and crystallization of (Ti-rich) Adr at the expense of Cpx and Prv. : harzburgite, blueschist, perovskite, andradite, fluid-rock interaction, Meliata Back-arc Basin Received: 22 July 2012; accepted: 23 December 2012; handling editor: E. Jelínek The online version of this article (http://dx.doi.org/10.3190/jgeosci.128) contains supplementary electronic material. Keywords

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Section: Introductionmentioning

confidence: 96%

The blueschist-associated perovskite-andradite-bearing serpentinized harzburgite from Dobšiná (the Meliata Unit), Slovakia

Putiš¹,

Koppa²,

Snarska³

et al. 2013

J. Geosci.

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“…Tables 1 and 2 ), whereas these elements are not present or in very small concentrations only in the dolomite marble (TiO2 < 0.08 wt%, Zr < 16 ppm, U ~ 6 ppm, Th < 0.1 ppm). Furthermore, the high sulfur, fluorine and phosphorus contents of the Ti-rich central vein zones (S up to 7 wt%; F~4000 ppm, P205 up to 2.3 wt%) are in sharp contrast to the extremely low concentrations found in the dolomite marble (S < 10 ppm, F = 50-150 ppm, P205 = 0.02-0.04 wt%), and thus document the presence and importance of these components in the metasomatic fluid where they are most probably partly responsible for complexing of high-valence cations (for discussion, see Gier6, 1990a).…”

Section: Whole-rock Compositionmentioning

confidence: 86%

“…In the Adamello example the veinforming fluid contained elevated concentrations of the hard ligands fluoride and phosphate, which thus are the most likely ligands for complexing the REE (cf. Gier6, 1990aGier6, , b, 1992. Similarly, the suggested REE-S -~I complexes probably play only a minor role in the submarine hydrothermal vent fluids where chloride is the main anion.…”

Section: Transport Of Reementioning

confidence: 99%

“…Agapova et al (1989) demonstrated that the solubility of anatase increases with increasing contents of total reduced sulfur in hot sulfidecarbonate solutions (200°C, 100 atm; constant pH of intermediate value); from these results they concluded that Ti forms mixed-ligand bisulfide-carbonate-hydroxide complexes. Since Ti is a prominent metal in the REE-rich zirkelite-jordisite veins and often behaves similarly to the REE in hydrothermal fluids (Gier6, 1990a), the experiments of Agapova et al (1989) contribute to understanding the formation of these veins, particularly because the studied solutions appear to be very effective also in transporting Mo and U (Agapova et al, 1987).…”

Section: Transport Of Reementioning

confidence: 99%

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Transport and deposition of REE in H2S-rich fluids: evidence from accessory mineral assemblages

Gieré

1993

Chemical Geology

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It is shown in four examples from geologically different environments that accessory or minor minerals rich in rare-earth elements (REE) are often texturally associated with base-metal sulfides. The examples demonstrate that REE can migrate in hydrothermal fluids containing large amounts of reduced sulfur (S -n) species, i.e. H2S, HS-and S 2-. In certain fluids complexes of REE with S -II species may be important for the REE transport, but most probably only in the absence of other strong ligands such as fluoride, carbonate or possibly phosphate. Textural relationships and geochemical data suggest that the formation of REE-bearing minerals in s-n-rich environments is genetically related to the precipitation of basemetal sulfides.

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“…The skarned rocks at the Shizhyuan W, Sn, Bi, and Mo deposit in South China also show an increase in REE (Chen et al, 1992). At the Bergell and Adamello contact aureoles in Italy, Ti, Zr, U, Th, Y and REE were found to have migrated in a potassium-rich fluid (Gieré, 1989). These three studies are in agreement with the results of the Canton Saint-Onge wollastonite deposit were there is an increase in REE in the calc-silicate rocks as compared to the marbles.…”

Section: Nature Of the Fluidmentioning

confidence: 94%

origin of the Canton Saint-Onge wollastonite deposit, Lac-Saint-Jean, Québec /

Beisswenger¹

1996

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Wollastonite is a naturally occurring anhydrous, fibrous calc-silicate mineral. As an industrial mineral it is particularly valuable for use in ceramic applications and its acicularity makes it an attractive and safe replacement for asbestos.Wollastonite is formed by the reaction of calcite with silica which gives off CO 2 ; heat is needed to drive the reaction to completion. The heat can be provided by regional or contact metamorphism, the silica can be provided by quartz mixed with a limestone protolith or from a magmatic fluid of an intruding pluton.The Canton Saint-Onge wollastonite deposit is situated near the centre of the LacSaint-Jean Anorthosite Complex. A major NE-SW trending lineament, the Lacs-SaintJean-Pipmuacan lineament, cuts the anorthosite. It stretches for over 200 km and is marked by solid state deformation and plutons of various composition and age. A lens of metasediments is preserved adjacent to this lineament. The metasediments include: hornfelsic gneiss, marbles, quartzite and the calc-silicate rocks which host the wollastonite.The wollastonite occurs in a band of calc-silicate rocks trending N040° that are in contact with marble to the south-east which is in turn in contact with the Du Bras Pluton bordering a gabbroic faciès of the anorthosite. The contact to the south-west is with the Astra syenite, a late undeformed pluton. The north-eastern contact is hidden by a valley without outcrop but on its other side there are wollastonite-free calc-silicate rocks followed by anorthosite. The wollastonite is interlayered with diopside on the millimetre to centimetre scale and strongly folded. Electron microprobe analyses of the layering shows that it is chemically abrupt, with no gradation in chemical composition between layers.Whole-rock oxygen isotope ratios were measured to determine the origin of the fluids involved in the formation of the deposit. Both granitoids and the Lac-Saint-Jean Anorthosite have 6 If the marbles are the protolith to the calc-silicate rocks some fluid must have been involved in order to lower the isotopic ratios of the latter. The data indicates that pristine meteoric water was not involved in the formation of the calc-silicate rocks, which would have resulted in lower, near zero isotopic values for the calc-silicate rocks. The fluid may 11 have been derived from one or more of the intrusions, or it may have been meteoric water that re-equilibrated with one of the intrusions. The generally lower values of the wollastonite-bearing calc-silicate rocks suggests that more fluid was involved in their formation as compared to the wollastonite-free rocks, if both came from a protolith with similar 518 O values.The stable isotope work suggests that the fluid concerned is in isotopic equilibrium with the plutons and possibly emanated from one of them. The fluid must have been rich in H 2 O to lower the partial pressure of the CO 2 and in silica in order to complete the reaction from calcite to wollastonite. The whole rock geochemistry suggests the fluid also contained...

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Hydrothermal mobility of Ti, Zr and REE: examples from the Bergell and Adamello contact aureoles (Italy)

Cited by 104 publications

References 29 publications

The blueschist-associated perovskite-andradite-bearing serpentinized harzburgite from Dobšiná (the Meliata Unit), Slovakia

The blueschist-associated perovskite-andradite-bearing serpentinized harzburgite from Dobšiná (the Meliata Unit), Slovakia

Transport and deposition of REE in H2S-rich fluids: evidence from accessory mineral assemblages

origin of the Canton Saint-Onge wollastonite deposit, Lac-Saint-Jean, Québec /

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