New constraints for the alpine HP metamorphism of the Ios basement, Cyclades, Greece

PDF
Published: Jan 1, 2001
DOI: https://doi.org/10.12681/bgsg.17130
Keywords:
Ios island Cyclades pre-Alpine basement Alpine HP metamorphism
M. PERRAKI
National Technical University of Athens, Section of Geological Sciences
E. MPOSKOS
National Technical University of Athens, Section of Geological Sciences
Abstract

The pre-Alpine basement of the Ios Island involves large Variscan granitoid bodies intruded into metasediments that had already been metamorphosed under upper amphibolite facies conditions, as it is indicated by residual migmatitic textures and deformed muscovite pegmatites. The Alpine HP-metamorphism, documented on various cycladic islands, has, also, affected the basement rocks of Ios. Pressures of '25 Kbar and temperatures of '540 °C, are estimated for the Alpine HP event, applying the chloritoid-chlorite and garnetclinopyroxene geothermometers, and the garnet-phengite-omphacite and garnet-rutile-quartz-sphene-clinozoisite geobarometers. Garnet-hornblende geothermometry yielded temperatures of '520 °C and garnet-chlorite geothermobarometry yielded temperatures of 450 °C at 15 Kbar. This suggests that, at least the first stages of decompression were accompanied by cooling, indicating a rapid exhumation, related to tectonic processes.

Article Details
  • Section
  • Petrology
Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Authors who publish with this journal agree to the following terms:

Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution Non-Commercial License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.

Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g. post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal. Authors are permitted and encouraged to post their work online (preferably in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work.

Downloads
Download data is not yet available.
References
ALTHERR R., KREUTZER H., WENDT J., LENZ H., WAGNER G.A., KELLER J., HARRE W., HOENDORF A. 1982. A late Oligocene/Early Miocene High Temperature Belt in the Attic-Cycladic Crystalline Complex SE Pelagonian, Greece. Geol. Jb., E23, 97-164, Hanover
ANDRIESSEN P.A.M., BANGA G & HEBEDA E.H. 1987. Isotopie age study of pre-Alpine rocks in the basal units on Naxos, Sikinos and Ios, Greek Cyclades. Geologie Mijnb. 66, 3-14
BERMAN, R.G. 1990. Mixing properties of Ca-Mg-Fe-Mn garnets, Am. Mineral., 75, 328-344
BERMAN R.G. 1991. Thermobarometry using multiequilibrium calculations: a new technique with petrologie applications. Canadian Mineralogist, 29, 833-855.
BROECKER M. & ENDERS L. 1999. U-Pb zircon geochronology of unusual ecligite-facies rocks from Syros and Tinos (Cyclades, Greece). Geol. Mag., 136, 111-118
BUCHER, Κ. & FREY, M. 1994. Petrogenesis of metamorphic rocks. Springer Verlag
DURR C, ALTHERR R., KELLER J., OKRUSCH M., SEIDEL E. 1978. The Median Aegean Crystalline Belt: Stratigraphy, Structure, Metamorphism, Magmatism. Alps, Apennines, Hellenides. Edited by H. Closs-D. Roeder- K. Schmidt, Int. Un. Com on Geod., Sc. Rep., 38, 455-477
ENGEL M. & REISCMANN T. 1998. Single Zircon geochronology of orthogneisses from Paros, Greece, Bulletin of the Geol. Soc. Of Greece, xxxÉÉ, 3, 91-99
FERRY, J.M. & SPEAR, FS. 1978. Experimental calibration of the partitioning of Fe and Mg between biotite and garnet. Contrib. Mineral. Petrol, 66, 113-117
GRAHAM, CM. & POWELL, R. 1984. A garnet-hornblende geothermometer: calibration, testing and application to the Pelona Schist, Southern California, J. Metamorphic Geology, 2, 13-21
GRAMBLING J.A. 1990. internally-consistent geothermobarometry and H20 barometry in metamorphic rocks: the example garnet-chlorite-quartz. Contrib. Mineral. Petrol., 105, 617-628
HENJES-KUNST F. & KREUZER H. 1982. Isotopie dating of pre-alpidic rocks from the island of Ios (Cyclades, Greece). Contrib. Mineral. Petrol., 80, 245-253
LANGOSCH, Α., SEIDEL, E., STOSCH, H.G. & OKRUSCH, M. 2000. Intrusive rocks in the ophiolitic melange of Crete - Witnesses to a Late Cretaceous thermal event of enigmatic geological position Contrib. Mineral. Petrol., 139,339-355
MANNING, C. E. & BOHLEN, S.R. 1991. The Reaction Titanite+Kyanite=Anorthite+Rutile and Titanite-Rutile Barometry in Eclogites, Contrib. Mineral. Petrol., 109, 1-9.
PAPANIKOLAOU D. 1996. The tectonostratigraphic terranes of the Hellenides. Ann. Geol. Payes Helléniques, 495-514
PAPANIKOLAOU D. & DEMIRTASLI E. 1987. Geological correlations between the Alpine segments of the Hellenides-Balcanides and Taurides-Pontides. Mineralia Slovaka, Monography, 387-396
POWELL R. 1985. Regression diagnostics and robust regression in geothermometer/geobarometer calibration:the garnet-clinopyroxene geothermometer revisited, J. Metamorphic Geol., 2, 33-42
VANDENBERG L. & LISTER G. 1996. Structural analysis of basement tectonites from the Aegean metamorphic core complex of Ios, Cyclades, Greece. /. Structural Geology, 18, 1437-1454
VAN DER MAAR P. 1981. Metamorphism on Ios and the geological history of the Southern Cyclades, Greece. Geologica Ultrajectiva, 28, 1-142
VIDAL, Ο., GOFFE, Β., BOUSQUET, R. & PARRÀ, T. 1999. Calibration and testing of an empirical chloritoidchlorite Mg-Fe exchange thermometer and thermodynamic data for daphnite, J. Metamorphic Geology, 17, 25-39
WATERS, D. & MARTIN, H.N. 1993. The garnet-clinopyroxene-phengite barometer, Terra Abstr., 5, 410-411
Most read articles by the same author(s)