PATTERNS OF DUCTILE DEFORMATION IN ATTICO-CYCLADIC MASSIF


D. Spanos
I. Koukouvelas
S. Kokkalas
P. Xypolias
Résumé
The area of Lavrion constitutes the westernmost part of the Attico-Cycladic massif where the allochthonous Cycladic Greenschist-Blueschist unit overthrusts the para-authochthonous Basal unit. The tectonic contact of these units forms a crustal scale thrust zone which is the continuation of the Evia thrust. Our research was focused on quartz-rich schists of the overlying allochthonous unit. Combination of microstructural, finite strain data and quartz and calcite c-axis fabrics analysis was used to characterize the kinematics of rock flow within the thrust zone. The latter was formed under conditions of progressive exhumation and decompression of the high-pressure schists of the AtticoCycladic massif. A dominant top-to-the-ENE sense of shearing along the thrust zone is inferred by several shear sense criteria. The analysis of several specimens collected from various structural depths manifest that the deformation close to the thrust zone occurred under approximately plane strain conditions and was characterized by an Rxz strain ratio which fluctuates between 3 and 6.5.
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  • Rubrique
  • General and Structural Geology
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Références
Altherr, R., Schliestedt, M., Okrusch, M., Seidel, E., Kreuzer, H., Harre, W., Lenz, H., Wendt, I., Wagner,
G. A. 1979. Geochronology of high pressure rocks on Sifnos (Cyclades, Greece). Contributions
to Mineralogy and Petrology, 70, 245-255.
Anders, B., Reischmann, T., Kostopoulos, D., 2007. Zircon geochronology of basement rocks from the
Pelagonian Zone, Greece: constraints on the pre-Alpine evolution of the westernmost Internal Hellenides.
International Journal of Earth Sciences, 96, 639-661.
Avigad, D., Garfunkel, Z., Jolivet, L., Azanon, J.M., 1997. Back arc extension and denudation of Mediterranean
eclogites. Tectonics, 16, 924-941.
Baltatzis, E., 1996. Blueschist-to-greenschist transition and the P–T path of prasinites from the Lavrion
area, Greece. Mineralogical Magazine, 60, 551–561.
Barton, C.M., 1976. The tectonic vector and emplacement age of an allochthonous basement slice in the
Olympos area, N.E. Greece. Bulletin de la Société Géologique de France, 18, 253-258.
Baziotis, I., Proyer, A. and Mposkos, E., 2009. High-pressure/low-temperature metamorphism of basalts
in Lavrion (Greece): implications for the preservation of peak metamorphic assemblages in blueschists
and greenschists Eur. J. Mineral. 2009, 21, 133–148.
Bröcker, M., 1990. Blueschist-to-greenschist transition in metabasites from Tinos Island (Cyclades,
Greece): Compositional control or fluid infiltration. Lithos, 25, 25–39.
Bröcker, M., Bieling, D., Hacker, B., Gans, P., 2004. High-Si phengite records the time of greenschist facies
overprinting: Implications for models suggesting megadetachments in the Aegean Sea. Journal
of Metamorphic Geology, 22, 427-442.
Doutsos, T., Piper, G., Boronkay, K., Koukouvelas, I., 1993. Kinematics of the Central Hellenides. Tectonics,
, 936-953.
Hirth, G. and Tullis, J., 1992. Dislocation creep regimes in quartz aggregates. Journal of Structural Geology,
, 145-159.
Katsikatsos, G., Migiros, G., Triantaphyllis, M., Mettos, A., 1986. Geological structure of Internal Hellenides.
Institute of Geological and Mining Exploration, Athens. Geological and Geophysical Research,
Special Issue, 191-212.
Katzir, Y., Avigad, D., Matthews, A., Gurfunkel, Z., Evans, B.W., 2000. Origin, HP/LT metamorphism and
cooling of ophiolitic mélanges in southern Evia (NW Cyclades), Greece. Journal of Metamorphic
Geology, 18, 699-718.
Kessel, G., 1990. Untersuchungen zur Deformation und Metamorphose in Attischen Krystallin, Griechenland.
Berliner Geowissenschaftlicher Abhandlungen, A126, 1–150.
Klepeis, K. A., Daczko, N.R., Clarke, G.L., 1999. Kinematic vorticity and tectonic significance of superposed
mylonites in a major lower crustal shear zone, northern Fiordland, New Zealand. Journal
of Structural Geology, 21, 1385-1405.
Law, R.D., Casey, M., Knipe, R.J., 1986. Kinematic and tectonic significance of microstructures and crystallographic
fabrics within quartz mylonites from the Assynt and Eriboll regions of the Moine thrust
zone, NW Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences, 77, 99-126.
Law, R.D., Schmid S.M., Wheeler, J., 1990. Simple shear deformation and quartz crystallographic fabrics:
a possible natural example from the Torridon area of NW Scotland. Journal of Structural Geology,
, 29-45.
XLIII, No 1 – 376
Lisle, R.J., 1985. Geological Strain Analysis. A Manual for the Rf /j method. Pergamon Press, New York.
Lister, G.S., 1977. Discussion: Crossed girdle c-axis fabrics in quartzites plastically deformed by plane
strain and in progressive simple shear. Tectonophysics, 39, 51-54.
Marinos, G.P. and Petrascheck, W.E., 1956. Laurium. Geological and Geophysical Research 4/1, Institute
for Geology and Subsurface Research, Athens, 1–247.
Mountrakis, D., 1986. The Pelagonian zone in Greece. A polyphase-deformed fragment of the Cimmerian
continent and its role in the geotectonic evolution of the eastern Mediterranean. Journal of Geology,
, 335-347.
Mulchrone, K.F. and Meere, P.A., 2001. Windows program for the analysis of tectonic strain using deformed
elliptical markers. Computers and Geosciences, 27, 1251–1255.
Mulchrone, K.F., Meere, P.A., Roy Choudhury, K., 2005. SAPE: a program for semi-automatic parameter
extraction for strain analysis. Journal of Structural Geology, 27, 2084-2098.
Passchier, C.W., 1997. The fabric attractor. Journal of Structural Geology, 19, 113-127.
Photiades, A. and Carras, N., 2001. Stratigraphy and geological structure of the Lavrion area (Attica,
Greece). Bull. Geol. Soc. Greece. 34/1, 103-109.
Platt, J.P. and Vissers, R.L.M., 1980. Extensional structures in anisotropic rocks. Journal of Structural Geology,
, 397-410.
Ramsay, J.G. and Huber, M.I., 1987. The Techniques of Modern Structural Geology, vol. 2. Academic
Press, New York.
Ring, U. and Reischmann, T., 2002. The weak and superfast Cretan detachment, Greece: exhumation at
subduction rates in extruding wedges. Journal of the Geological Society, London, 159, 225–228.
Ring, U., Glodny, J., Will, T., Thomson, S., 2007. An Oligocene extrusion wedge of blueschist-facies
nappes on Evia, Aegean Sea, Greece: implications for the early exhumation of high-pressure rocks.
Journal of the Geological Society, London, 164, 637-652.
Schermer, E.R., 1993. Geometry and kinematics of continental basement deformation during Alpine
orogeny, Mt. Olympos region, Greece. Journal of Structural Geology, 15, 571-591.
Shaked, Y., Avigad, D., Garfunkel, Z., 2000. Alpine high-pressure metamorphism at the Almyropotamos
window (southern Evia, Greece). Geological Magazine, 137, 367-380.
Simpson, C. and De Paor, D.G., 1997. Practical analysis of general shear zones using the porhyroclast hyperbolic
distribution method: an example from the Scandinavian Caledonides. In: SENGUPTA, S. (ed.)
Evolution of Geological Structures in Micro- to Macro-scales. London: Chapman & Hall, 169-184.
Skarpelis, N., Tsikouras, B., Pe-Piper, G., 2008. The Miocene igneous rocks in the Basal Unit of Lavrion
(SE Attica, Greece): petrology and geodynamic implications. Geological Magazine, 145, 1-15.
Stouraiti, C., Mitropoulos, P., Tarney, J., Barreiro, B., McGrath, A.M., Baltatzis, E., 2009. Geochemistry
and petrogenesis of late Miocene granitoids, Cyclades, southern Aegean: nature of source components.
Tomaschek, F., Kennedy, A.K., Villa, I.M., Lagos, M., Ballhaus, C., 2003. Zircons from Syros, Cyclades,
Greece –recrystallization and mobilization of zircon during high-pressure metamorphism. Journal of
Petrology, 44, 1977–2002.
Trotet, F., Jolivet, L., Vidal, O., 2001. Tectono-metamorphic evolution of Syros and Sifnos islands (Cyclades,
Greece). Tectonophysics, 338, 179-206.
Turner, F.J. and Weiss, L.E., 1963. Structural analyses of metamorphic tectonites.
Wenk, H.R., Takeshita, T., Bechler, E., Erskine, B.G., Matthies, S., 1987. Pure shear and simple shear calcite
textures. Comparison of experimental, theoretical and natural data. Journal of Structural GeolXLIII,
No 1 – 377
ogy, 9, 731-745.
Xypolias, P., Kokkalas, S., Skourlis, K., 2003. Upward extrusion and subsequent transpression as a possible
mechanism for the exhumation of HP/LT rocks in Evia Island (Aegean Sea, Greece). Journal of
Geodynamics, 35, 303-332.
Xypolias, P., Chatzaras, V., Koukouvelas, I. K., 2007. Strain gradients in zones of ductile thrusting: Insights
from the External Hellenides. Journal of Structural Geology, 29, 1522-1537.
Xypolias, P., Spanos, D., Chatzaras, V., Kokkalas, S., Koukouvelas, I., 2010. Vorticity of flow in ductile
thrust zones: examples from Attico-Cycladic Massif (Internal Hellinides, Greece). In: Law, R. D.,
Butler, R. W. H., Holdsworth, R., Krabendam, M. & Strachan, R. (eds) Continental Tectonics and
Mountain Building – The Legacy of Peach and Horne, Geological Society, London, Special Publications,
, in press.
Yonkee, A., 2005. Strain patterns within part of the Willard thrust sheet, Idaho–Utah–Wyoming thrust belt.
Journal of Structural Geology, 27, 1315-1343.
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