| More

PATTERNS OF DUCTILE DEFORMATION IN ATTICO-CYCLADIC MASSIF

Views: 454 Downloads: 549
D. Spanos, I. Koukouvelas, S. Kokkalas, P. Xypolias
D. Spanos, I. Koukouvelas, S. Kokkalas, P. Xypolias

Abstract


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.

Keywords


finite strain; quartz c-axis fabrics; calcite c-axis fabrics;

Full Text:

PDF

References


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.


Refbacks

  • There are currently no refbacks.


Copyright (c) 2017 D. Spanos, I. Koukouvelas, S. Kokkalas, P. Xypolias

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