The `Cretan detachment` and adjacent units in eastern Crete: Structure, kinematics, deformation mechanisms, and metamorphic evolution

克里特岛的上、下阿尔卑斯山推复被“克里坦拆离”隔开，通常被解释为一条大位移的伸展剪切带，它促成了脚壁的折返俯冲岩。中新世的伸展作用被认为是受希腊俯冲带的退缩控制。支持沿‘克里坦滑脱’的伸展运动的一个理由是，假设的上盘(Tripolitza单元)的非变质岩石位于脚壁(PhylliteQuartzite或Pltenkalk单元)的变质岩石之上。然而，来自克里特岛东部的第一个显微组构、应变和伊利石结晶度数据表明，当穿过‘克里坦滑脱’时，发生了逆变质作用，这意味着极低级别的变质特里波利扎石灰岩寄生在千粒状石英岩单元的几乎未变质的岩石上。因此，在克里特岛东部，“克里坦支队”可能会形成一个冲断，其运动应该会导致地壳增厚。本项目将侧重于这一假设，因为(1)“克里坦支队”对东地中海地区的阿尔卑斯山地球动力学具有重要意义，(2)“克里坦支队”可能被国际地球科学中心在梅萨拉地堡的钻探所穿透。

The upper and lower Alpine nappes of Crete are separated by the 'Cretan detachment', which is commonly interpreted to represent a large-displacement extensional shear zone that contributed to exhume subducted rocks of the foot wall. Miocene extension is supposed to have been controlled by roll back of the Hellenic subduction zone. One reason to argue for extensional movements along the 'Cretan detachment' is the fact that supposed nonmetamorphic rocks of the hanging wall (Tripolitza unit) are resting on top of metamorphic rocks of the foot wall (PhylliteQuartzite or Plattenkalk unit). First microfabric, strain and illite-crystallinity data from eastern Crete, however, suggest inverse metamorphism when crossing the 'Cretan detachment', meaning that very-low grade metamorphic Tripolitza limestone is resting on almost nonmetamorphic rocks of the PhylliteQuartzite unit. Thus, in eastern Crete the 'Cretan detachment' might form a thrust, the movements of which should have led to crustal thickening. The present project will focus on this hypothesis because (1) the 'Cretan detachment' is of major importance for the Alpine geodynamics of the eastern Mediterranean area, and (2) the 'Cretan detachment' could be penetrated by ICDP drillings in the Mesara graben.