Blueschist-to-greenschist transition in metabasites from Tinos Island, Cyclades, Greece; compositional control or fluid infiltration?
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|Author Affiliations:||Primary: |
Univ. California, Dep. Geol., Davis, CA, United States
|Volume Title:||Third international eclogite conference|
|Volume Authors:||Okrusch, M., editor|
|Source:||Lithos (Oslo), 25(1-3), p.25-39; Third international eclogite conference, Wurzburg, Federal Republic of Germany, April 18-21, 1989, edited by M. Okrusch. Publisher: Elsevier, Amsterdam, International. ISSN: 0024-4937|
|Note:||In English; illus. incl. 39 anals., strat. col., 6 tables, geol. sketch map|
|Summary:||The metamorphic history of the lower unit of Tinos Island is characterized by a multistage blueschist event with peak conditions in the Eocene (P 12-20 kbar, T 450-550 degrees C) and subsequent greenschist-facies overprint at somewhat lower T and at P of 4-7 kbar which culminated at the Oligocene/Miocene boundary. Rocks of different metamorphic grade and age occur in coherent sequences as a consequence of incomplete re-equilibration during retrograde uplift. Continuous transitions with all gradations from garnet-, epidote- and omphacite-bearing high-P rocks to greenschist-facies assemblages can be found on outcrop, sample and thin-section scales. Locally, retrogression advances parallel to the stratigraphy, which indicates channelled infiltration of a fluid phase, presumably controlled by differences of permeability and/or structural factors. The whole-rock compositions of metabasic blueschists and their greenschist-facies equivalents provide no conclusive evidence that the persistence of some high-P assemblages during decompression was controlled by geochemical differences inherited from the protoliths. [G.R.]|
|Subjects:||Blueschist facies; Facies; Fluid phase; Greenschist facies; Infiltration; Major elements; Metabasite; Metaigneous rocks; Metamorphic rocks; Metamorphism; Retrograde metamorphism; Trace elements; Aegean Islands; Cyclades; Europe; Greece; Greek Aegean Islands; Mediterranean region; Southern Europe; Tinos|
|Copyright Information:||GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique|
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