Lawsonite Pseudomorphs: a strain-free gauge in exhuming blueschists
Abstract
The kinematics records of subduction and exhumation in Blueschists rocks of Syros (Cyclades; Greece) can be deciphered thanks to Lawsonite pseudomorphs. Since Lawsonite is a hydrous HP mineral that crystallizes along prograde rock paths and undergoes breakdown during decompression, Lawsonite pseudomorphs consist in a useful strain-free gauge to identify deformation that occurred before its destabilization. The preservation of lawsonite crystal shape despite complete retrogression indicates that the blueschist host rock has not been affected by penetrative deformation during exhumation. Using this strain-free indicator as a tool, it is shown that in the Cyclades, subduction related deformation occurred with a sense of shear top to S or SW, prior to 52 Ma and is followed by exhumation with a top to NE sense of shear.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.V33A2347M
- Keywords:
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- 8170 TECTONOPHYSICS / Subduction zone processes