Abstract
Jurassic subduction initiation in the Neo-Tethys Ocean eventually led to the collision of the Adria-Africa and Eurasia continents and the formation of an ~6,000 km long Alpine orogen spanning from Iberia to Iran. Reconstructing the location and geometry of the plate boundaries of the now disappeared Neo-Tethys during the initial moments of its closure is instrumental to perform more realistic plate reconstructions of this region, of ancient ocean basins in general, and on the process of subduction initiation. Neo-Tethyan relics are preserved in an ophiolite belt distributed above the Dinaric-Hellenic fold-thrust belt. Here we provide the first quantitative constraints on the geometry of the spreading ridges and trenches active in the Jurassic Neo-Tethys using a paleomagnetically based net tectonic rotation analysis of sheeted dykes and dykes from the West and East Vardar Ophiolites of Serbia (Maljen and Ibar) and Greece (Othris, Pindos, Vourinos, and Guevgueli). Based on our results and existing geological evidence, we show that initial Middle Jurassic (~175 Ma) closure of the western Neo-Tethys was accommodated at a N-S trending, west dipping subduction zone initiated near and parallel to the spreading ridge. The West Vardar Ophiolites formed in the forearc parallel to this new trench. Simultaneously, the East Vardar Ophiolites formed above a second N-S to NW-SE trending subduction zone located close to the European passive margin. We tentatively propose that this second subduction zone had been active since at least the Middle Triassic, simultaneously accommodating the closure of the Paleo-Tethys and the back-arc opening of Neo-Tethys.
| Original language | English |
|---|---|
| Pages (from-to) | 858-887 |
| Number of pages | 30 |
| Journal | Tectonics |
| Volume | 37 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Mar 2018 |
Funding
M. M. and D. J. J. vH. acknowledge funding through an ERC Starting grant (to D. J. J. vH., project 306810–SINK) and an NWO VIDI grant (to D. J. J. vH., project 86411004). We thank Noortje van Rijsingen for her help in the field in Greece and for the laboratory analyses of the Greek ophiolite samples. We are thankful to Vladica Cvetković and Kristina Šarić and Liviu Matenco for providing advice on suitable field locations in Serbia and Greece. We thank Ayten Koç for her help in the field in Serbia. Fruitful discussion with Stefan Schmid greatly helped to clarify critical aspects of the complex geology of the Balkan Peninsula. We are thankful to Michele Marroni and an anonymous reviewer for constructive comments, which helped to substantially improve the original manuscript. All data presented in this paper are available in the supporting information.
Keywords
- Balkans
- Jurassic
- Neo-Tethys
- ophiolites
- spreading ridge
- subduction initiation