Project

Tethys; Modelling; Subduction; Suture; Collision

Lead
La zone de subduction et collision téthysienne en Azerbaïdjan d'Iran
Lay summary
Ce projet concerne l'Azerbaïdjan d'Iran. Il s’agit de comprendre comment une ou plusieurs collisions ont façonné cette région très active du Plateau iranien et quelles en sont les incidences sur la convergence entre l'Arabie et l'Eurasie. Nous reconstruirons, dans le temps et dans l'espace, le cadre géologique de la tectonique récente, très actives en Azerbaïdjan d’Iran. Nous nous concentrerons sur la géologie pré- et syn-collisionelle pour répondre à des questions cruciales sur l'anatomie de la ceinture orogénique téthysienne et sa géodynamique. Ces questions comprennent la structure des unités plutoniques et des roches métamorphiques mésozoïques, leur contexte tectonique et l'influence des structures héritées sur la formation du plateau irano-turque Les réponses s’appuierons sur (1) la cartographie de régions clefs, en mettant l'accent sur l'information cinématique, (2) l’étude pétrographique et géochimique des échantillons replacés dans leur cadre structural et géochronologique et (3) la modélisation numérique pour contraindre de façon plus quantitative que les modèles actuels comment les divers systèmes de subduction interagissent. L’importance régionale vient de l'absence d'information détaillée et moderne sur les roches que nous étudierons. Les résultats analytiques (thermo-barométrie des roches métamorphiques, géochimie et datation multi-méthode) seront implémentés dans la modélisation numérique. Les modèles géodynamique conduiront à des résultats régionaux et thématiques concernant la subduction, la rupture de slab et la délamination du manteau lithosphérique. Ce travail fournira un contexte plus large à de nouvelles données et apportera un nouvel éclairage sur cette partie mal connue du système de collision Alpes-Himalaya.

Direct link to Lay Summary

Last update: 14.04.2014

Active participation

Number	Title	Start	Funding scheme

This project is a continuation and extension of the NSF/ETH/Geological Survey of Iran (GSI) projects started in 2004 and finished in December 2013 (N° 2-77634-05 and 2-77500-12). It is also a new project in the sense that it extends previous work on Makran and Zagros to the northwestern, Azarbaijan part of Iran. This geographical shift was desirable because the scientific work we could produce in the Makran-Sistan region in our core discipline is essentially finished. It has also been strongly recommended by our Iranian partners for safety reasons. This shift in study area explains the break between the end of previous projects and the starting time of this one. This apparent interruption was used as time necessary for scientific consideration and a preliminary visit to ensure the feasibility of the new project, which has been done. Yet, the general problematic on the Tethys collision system remains the same. With the present project, we also extend the work carried out with NSF projects N° 21-39080.93 and 20-49372.96 on collision of arc systems. To our advantage, access to the field area is politically easier than it was to the Makran and Sistan areas. We want to investigate to what extent single or multiple collisions and orogeny have shaped the northwestern Iranian Plateau and may have impacted recent kinematics of convergence. In particular, we want to understand changes in the deformation style within the collision zone and the effects of several possibly coeval events, such as coeval closure of two suture zones separated by an arc and possibly followed by slab break-off (s). Much has been done on the neotectonics of the region. We do not wish to repeat this previous work but, instead, build up the longer term history of the Azerbaijan Plateau, which makes the large-scale framework (both in time and space) of recent tectonics. For these reasons, we will focus on the older pre- and syncollisional geology with the aims to solve critical questions on the anatomy of the orogenic belt and its geodynamics. These questions include fabrics of Mesozoic plutonic units and of metamorphic rocks involved in the tectonic imbrications and their geodynamic context at that time as well as the influence of inherited structures on the plateau evolution. To find answers, we propose to (1) upgrade mapping of critical areas, with focus on the kinematic information, (2) extend petrological and geochemical knowledge in the frame of a structural and geochronological framework and (3) direct our modelling efforts towards the understanding of how multiple subduction systems interact in a more quantitative way than existing geodynamic models allow. Field work will complement and integrate current studies by the Geological Survey of Iran. Regional interest comes from the lack of detailed information on the rocks we will study. Sample analyses (thermo-barometry of metamorphic rocks, geochemistry and multi-method dating) will be implemented in numerical, geodynamic modelling will lead to both regional and thematic results as far as subduction, slab break off and/or mantle delamination are involved. This work will provide a wider context to our new data by shedding new light on that part of the Alpine Himalayan collisional system.In continuity and in balance with previous, finished projects, we request two PhD students to perform this study. They will gain field training and experience into complementary aspects of cutting-edge analytical, thematic and numerical approaches. The work involves collaboration with other scientists of the Department of Earth Sciences at the ETH and will strengthen the already established collaboration with the Geological Survey of Iran.