Exhumation of Attica high-pressure rocks in a subduction channel: new metamorphic PT constraints from Attica, NW Cyclades, Greece

Baziotis Ioannis, Mposkos Evripides, F. Windley Brian, Thomas N. Lamont

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The Hymettus area in East Attica contains predominantly greenschist facies schists and marbles; blueschist-facies key minerals are absent in the matrix. However, blueschist facies P-T conditions are recorded in the phyllosilicate mineral chemistry. We provide new integrated thermodynamic data from a lower tectonic unit indicating that the metamorphic path for both prograde and retrograde metamorphism was similar to that in other parts of the Cycladic Blueschist Unit (CBU). New P-T data from the Hymettus area show that a peak pressure of ∼1.4 ± 0.05 GPa was reached at ∼300 ± 25 ºC, followed by exhumation, first with a significant temperature increase to ∼470 ± 20 °C at a pressure of ∼0.8 ± 0.1 GPa, followed by major cooling. The mechanism that exhumed the Hymettus rocks is interpreted to be wedge extrusion in a subduction channel. Accordingly, the 15 km difference in pressure (>0.5 GPa) between the lower and upper tectonic units was eliminated by their juxtaposition during their exhumation in the extruded wedge, which had a shallow-dipping, extensional fault at the top and a parallel thrust at the base. Retrogression of high-to low-pressure assemblages was a result of water infiltration from both sides of the wedge. Both these processes led to a typically symmetrical wedge structure with the relict HP rocks of the LTU in the centre, and the UTU lower pressure rocks in the upper margin.
Original languageEnglish
Article number105266
JournalLithos
VolumeIn press
Early online date1 Nov 2019
DOIs
Publication statusE-pub ahead of print - 1 Nov 2019

Keywords

  • Subduction zone metamorphism and exhumation
  • Hymettus area
  • Cycladic Blueschist Unit
  • Thermodynamic multi-equilibrium modeling

Fingerprint

Dive into the research topics of 'Exhumation of Attica high-pressure rocks in a subduction channel: new metamorphic PT constraints from Attica, NW Cyclades, Greece'. Together they form a unique fingerprint.

Cite this