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

克里特岛的上、下阿尔卑斯推覆体被“克里特岛拆离”隔开，通常认为这是一个大位移的伸展剪切带，有助于挖掘出下壁的俯冲岩石。中新世伸展受希腊俯冲带的回滚控制。主张沿“克里特拆离”伸展运动的一个原因是，假定上盘（Tripolitza单元）的非变质岩位于下盘（PhylliteQuartzite或Plattenkalk单元）的变质岩之上。然而，来自克里特岛东部的微结构、应变和伊利石结晶度数据表明，当穿过“克里特岛拆离”时，发生了逆变质作用，这意味着极低品位的变质Tripolitza石灰岩位于千层石英岩单元的几乎非变质岩石上。因此，在克里特东部，“克里特分离”可能形成一个逆冲，其运动应该导致地壳增厚。本项目将侧重于这一假设，因为(1)“克里特岛分离”对地中海东部地区的高山地球动力学具有重要意义，(2)“克里特岛分离”可以通过Mesara地槽的ICDP钻探穿透。

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.