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

克里特岛东部的“克里特支队”和邻近单位：结构、运动学、变形机制和变质演化

• 批准号: 5363787
• 负责人: Professor Dr. Gernold Zulauf
• 金额: --
• 依托单位: Arbeitsgruppe Strukturgeologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2002
• 资助国家: 德国
• 起止时间: 2001-12-31 至 2006-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5363787?language=en
• 关键词: Cretan; detachment; adjacent; units; eastern

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.

克里特岛的上部和下部高山推覆体被“克里特脱离”分开，该脱离通常被解释为代表大位移伸展剪切带，导致下盘俯冲岩石的挖出。中新世扩张被认为是由希腊俯冲带的回滚控制的。争论沿着“克里特岛脱离”的伸展运动的一个原因是，假定的上盘非变质岩（Tripolitza 单元）位于下盘变质岩（千枚岩石英岩或 Plattenkalk 单元）的顶部。然而，来自克里特岛东部的第一批微纤维、应变和伊利石结晶度数据表明，在穿越“克里特岛脱离”时发生了逆变质作用，这意味着极低品位的的黎波里察灰岩位于千枚岩石英岩单元的几乎非变质岩石上。因此，在克里特岛东部，“克里特脱离”可能会形成逆冲，其运动应该会导致地壳增厚。本项目将重点关注这一假设，因为 (1) “克里特岛脱离”对于东地中海地区的高山地球动力学具有重要意义，(2) “克里特脱离”可以被 Mesara 地堑中的 ICDP 钻探穿透。