The geological record of the lowermost tectonic unit of the Cretan nappe pile in the Talea Ori, Crete, Greece - the deformation history during burial and exhumation
Palaeontology
Final Report Abstract
The project yielded new insight into the deformation and stress history of metasediments exhumed from subductions zones as well as into the pre-alpine tectonic development of the Eastern Mediterranean. The main conclusions can be summarized as follows: The contact between the HP-LT metamorphic PQ s.str. and Talea Ori group is characterized by an extensional ductile shear zone resulting in the updoming of the Talea Ori group, respectively the downfaulting of the PQ s.str. In western Crete, a comparable ductile deformation in the PQ s.str. during exhumation is not recorded so far. - The main deformation mechanism in this shear zone is by high-strain-rate (10^-10 s^-1 to 10^-9 s^-1) dissolution-precipitation creep of the metasediments accompanied by cyclic cracking and sealing at relatively low stresses (tens of MPa) resulting in abundant discordant quartz veins along shear bands and boudin necks. Transient and local high stresses (few hundred MPa) are recorded in some quartz veins at temperatures close to peak metamorphic conditions, suggesting high (coseismic) stress-loading rates. - The siliciclastic rocks of the Talea Ori group most probably were deposited close to the southern active margin of Eurasia and not, as so far assumed, at the northern passive margin of Gondwana. This indicates that southward subduction and/or terrane displacement by strike-slip faults may have occurred in Late Triassic times in the Eastern Mediterranean. We feel that our results are relevant and stimulating to further evaluating the relationship between longterm high-strain and transient high-stress deformation in shear zones associated to the exhumation of HP-LT metamorphic rocks, as well as to resolve the complex puzzle of the geodynamic evolution in the Eastern Mediterranean.
Publications
- (2019). A ductile extensional shear zone at the contact area between HP-LT metamorphic units in the Talea Ori, central Crete, Greece: deformation during early stages of exhumation from peak metamorphic conditions. International Journal of Earth Sciences, 108(1), 213–227
Seybold, L., Trepmann, C. A., & Janots, E.
(See online at https://doi.org/10.1007/s00531-018-1650-6) - (2019). Deformation at low and high stress-loading rates. Geoscience Frontiers, 10(1), 43 – 54
Trepmann, C. A. & Seybold, L.
(See online at https://doi.org/10.1016/j.gsf.2018.05.002) - (2020). New constraints from U–Pb dating of detrital zircons on the palaeogeographic origin of metasediments in the Talea Ori, central Crete. Geological Magazine, 1-26
Seybold, L., Dörr, W., Trepmann, C., & Krahl, J.
(See online at https://doi.org/10.1017/S0016756819001365)
