Unravelling metamorphic ages of suture zone rocks from the Makran and Sabzevar areas (Iran):new constraints for the temporal evolution of the Arabia-Eurasian collision zone

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Many aspects of the geological, tectono-metamorphic and magmatic evolution of the suture zones surrounding Iranian microcontinental blocks are as yet poorly constrained and only known on a reconnaissance level. Especially the knowledge about the timing and geodynamic significance of regional metamorphic processes is fragmentary and needs further attention. Relative to its geographic extent, the regional coverage with isotopic age data is insufficient for meaningful interpretation of the geologic history. The lack of robust geochronological data is a major obstacle for in-depth understanding of the geodynamic evolution, improved regional correlations and refinement of the general geologic picture that has been strongly affected by the interaction between the Arabian, Eurasian and Afghan plates. In order to improve knowledge of the plate reorganizations controlling the geodynamic evolution of the Arabia-Eurasian collision zone this study seeks funding for field-based research in the Makran and Sabzevar areas, aiming to assist in building up a geochronological database that can serve as a framework for a more detailed geodynamic interpretation of the subduction–exhumation processes operating along the periphery of the Central Iranian Microcontinent. Deciphering of the tectonic and metamorphic evolution requires a solid geochronologic foundation. Previous studies have outlined the essential field and petrological context. Still, more research is needed to deepen our understanding of the P–T–D–t evolution of these occurrences. In order to fully understand the spatial and temporal evolution of the Iranian microplate collage, it will be necessary to unravel the complete metamorphic evolution by linking P–T and geochronological information, not only for the HP/LT rocks, but also for closely associated greenschist- and/or amphibolite facies rocks. Neither for the HP/LT stage nor for strongly overprinted rocks an adequate geochronological dataset is yet available, but is required to decipher the complete tectono-metamorphic histories of the suture zones. Accurate and precise ages are a prerequisite to avoid misinterpretation with far-reaching consequences for the understanding of a geological history. In order to better integrate the metamorphic rocks from the Makran and Sabzevar areas in geodynamic reconstructions, robust age constraints for the timing of metamorphism are of utmost importance. New perspectives for understanding of the broader geodynamic context can be expected by systematically closing the gaps in the still patchy geochronological investigation of the study areas. The main goal is to help establishing the essential temporal framework for the geodynamic history of the Arabia-Eurasian convergent boundary and to improve our understanding of the complex tectonometamorphic processes operating along this collision zone.