Upper crustal emplacement and deformation of grani

Authors: Tilo Kneuker Wolfgang Dörr Rainer Petschick Gernold Zulauf

Publish Date: 2014/11/14

Volume: 104, Issue: 2, Pages: 351-367

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Abstract

The present study is dealing with the emplacement and deformation of diorite and quartz diorite exposed along new road cuts between Agios Nikolaos and Sitia Uppermost Unit eastern Crete Mingling of both melt types is indicated by enclaves of diorite inside quartz diorite and vice versa The diorite and quartz diorite intruded into coarsegrained white marble which is in lateral contact to but also forms the roof of the intrusive body Evidence for contact metamorphism is indicated by increasing grain size of calcite in the marble with decreasing distance from the diorite U–Pb TIMS dating of zircons separated from quartz diorite yielded a concordant age at 740 ± 025 Ma which is interpreted as emplacement age As this age is close to published K–Ar cooling ages of hornblende and biotite the melt should have intruded and cooled down rapidly at upper structural levels which is not common for granitoids of the Uppermost Unit of Crete Upper crustal melt emplacement is also documented by stoped blocks and by the lack of any ductile viscous deformation The diorite and quartz diorite however are affected by strong postOligocene brittle faulting Paleostress analysis based on these faults revealed a change in stress field from N–S and NNW–SSE shortening by thrusting convergence between African and European plates to NNE–SSW and NE–SW shortening accommodated by strikeslip SWward extrusion of the Anatolian microplate Calcitetwin density indicates high differential stress 260 ± 20 MPa related to these phases of crustal shorteningSamples were prepared by E Gottwald and M Bladt their efforts are kindly acknowledged We further would like to thank M Fischer S Martha and B Wiesenbach for fruitful discussions regarding occurrences of Uppermost Unit slices on Anafi and southern Crete Thanks also for constructive comments by P A Ustaömer and M Bröcker Financial support of fieldwork by Hermann WillkommFoundation is gratefully acknowledged

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