Isotopic and petrological evidence for the infiltration of water-rich fluids during the Miocene M2 metamorphism on Naxos, Greece

Journal Article · Tue Aug 01 04:00:00 EDT 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90323-2· OSTI ID:7164155

Baker, J; Bickle, M J; Buick, I S; Holland, T J.B. ^[1]; Matthews, A ^[2]

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1. Univ. of Cambridge (England)
2. Hebrew Univ. of Jerusalem (Israel)

A detailed carbon and oxygen isotopic study, in conjunction with petrological work, has been carried out across calcite-dolomite marble layers in the high-grade metamorphic sequence on the island of Naxos, Greece. The purpose of this study is to examine fluid flow during the Miocene Barrovian metamorphic event. Individual marble bands show two dominant styles of isotopic alteration from core values of 22 to 29{per thousand} in {delta}{sup 18}O and 1 to 3{per thousand} in {delta}{sup 13}C. Cross-cutting relationships observed between these two alterations allow the relative timing of infiltration to be determined. The development of boundary layers is shown to result from the infiltration of fluids with isotopic signatures of 12 to 16{per thousand} in {delta}{sup 18}O and {minus}3 to {minus}12{per thousand} in {delta}{sup 13}C, and an X{sub CO{sub 2}} less than 0.3. These fluids are derived from dehydration of graphite-bearing pelites during the prograde metamorphism. These conclusions are at odds with those of previous workers who suggested that the prograde metamorphism was a result of the pervasive influx of mantle-derived fluids with X{sub CO{sub 2}} greater than 0.5. The alteration associated with vein networks results from peak to post-peak infiltration of fluids which drive decarbonation reductions. At least some of these fluids have an X{sub CO{sub 2}} less than 0.05, but this is obscured by the production of CO{sub 2} during the decarbonation reactions. These fluids were most probably produced from the crystallizing partial melts formed during the prograde metamorphism. These infiltrating fluids are thought to have {delta}{sup 18}O {le} 10{per thousand} and {delta}{sup 13}C of {minus}5 to {minus}7 per thousand.

• OSTI ID: 7164155
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 53:8; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

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58 GEOSCIENCES
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