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

• Applicant: Professorin Dr. Claudia Trepmann
• Subject Area: Mineralogy, Petrology and Geochemistry ; Palaeontology
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280061993

The study proposes to decipher the geological record of HP-LT metasediments at the base of the Talea Ori unit, i.e., the oldest and lowermost known structural level of the Cretan nappe pile. The aim is to obtain information on the long-time deformation and stress history during burial and exhumation. In the chosen study areas around the village Bali and west to the village Fodele, low-strain metapelites and conglomerates grade continuously into high-strain zones. The mineral association and microstructure of gneiss and schist components in low-strain conglomerates will be used to obtain information on the unknown pre-Alpine basement. The high-strain zones provide information on at least two different deformation stages: a scaly foliation, lineation and cm-scale folds are crosscut by shear bands and related quartz veins at a high angle. The spatial arrangement of the inferred deformation structures (foliation, lineation, folds, shear band, veins) will be investigated and interpreted in relation to the large-scale fold structure in the Talea Ori and to the northern bordering tectonic contact. The structural, chemical and crystallographic characteristics of the microfabrics related to the various mesoscopic structures will be analyzed to infer the deformation mechanisms and deformation conditions (temperature, stress, strain rate). Preliminary observations on high-strain zones reveal that the microfabrics related to shear bands and sheared quartz veins indicate high-stress crystal plastic deformation of quartz. The correlation of the field observations with the microfabric analyses will allow characterizing and separating the different deformation stages. Reconciling the contrasting rock records of low-stress/low-strain on the one hand and high-strain and locally high-stress on the other within one tectono-stratigraphic unit will be used to extract the rheological properties during the subduction history. Finally, the comparison of the inferred geological record of the base of the Talea Ori unit to the mesoscopic deformation structures and microfabrics of the unit in northern contact, where the structural position is debated controversially, will be used to elucidate the regional geology of the Talea Ori.

• DFG Programme: Research Grants