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

本研究拟破译位于Talea Ori单元底部的HP-LT变质沉积的地质记录，Talea Ori单元是克里特岛推覆堆最古老、已知最低的构造层。目的是获得在埋葬和挖掘期间的长期变形和应力历史信息。在Bali村周围和Fodele村以西所选择的研究区域，低应变变质岩和砾岩不断向高应变区演化。低应变砾岩中片麻岩和片岩组分的矿物组合和微观结构将用于获取未知的前阿尔卑斯基底的信息。高应变带提供了至少两个不同变形阶段的信息：鳞片状片理、线理和厘米级褶皱被剪切带和相关石英脉以高角度横切。根据塔里奥里大型褶皱构造和北部边缘构造接触，对推断出的变形构造（片理、线理、褶皱、剪切带、脉状）的空间排列进行研究和解释。分析与各种介观结构相关的微织物的结构、化学和晶体学特征，以推断变形机制和变形条件（温度、应力、应变速率）。高应变带的初步观察表明，与剪切带和剪切石英脉相关的微组构表明石英的高应力晶体塑性变形。现场观测与微结构分析的相关性将允许表征和分离不同的变形阶段。将同一构造地层单元内的低应力/低应变与高应变和局部高应力的对比岩石记录进行协调，提取俯冲历史时期的流变学性质。最后，将塔里奥里单元基底的推断地质记录与构造位置有争议的北部接触区塔里奥里单元的细观变形构造和微组构进行对比，阐明塔里奥里单元的区域地质。

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.