Timing of westward propagation of the North Anatolian Fault, Greece

Continental collision causes the build-up of large amounts of stress in the buckling crust. The stress causes rocks to deform on a range of timescales, both slowly over millions of years, and instantaneously in seismic events (earthquakes). Understanding the historical rates of movement along major seismically-active structures that have accommodated continental convergence is critical for comprehending the distribution of seismicity throughout time. This research project will use new direct dating techniques, combined with stable isotope analysis, to reconstruct the displacement history of the seismically active, North Anatolian Fault (NAF), which poses a major seismic hazard to large parts of Turkey, Greece and the surrounding area1-3.

The North Anatolian Fault (NAF) is a right-lateral transform plate boundary between Eurasia and Anatolia, which accommodates the south-westward extrusion of Anatolia (Fig. 1). The fault extends from north-eastern Turkey though Greece and is one of the most hazardous strike-slip faults on Earth. Despite this, the recent propagation of the fault across the north Aegean from Turkey to Greece is poorly constrained. The south-western terminus of the fault is marked by E-W to SE-NW trending active transtensional faults, which form the North Aegean Trough. Fortunately, the length of the NAF is straddled by a string of islands which span the North Aegean Sea into the Sporades in Greece. As these islands are comprised mainly of carbonate rocks4,5, they represent the ideal area to apply the novel U-Pb calcite dating technique. This cutting-edge technique, currently being developed in the University of Portsmouth (UoP), will allow calcite crystals formed along the fault surfaces to be dated for the first time. By collecting and dating rocks from both the north-eastern and south-western extremes of the NAF in the Aegean and Sporades, it will be possible to constrain the timing of fault propagation and thus reconstruct historic movement on the NAF.

Aims: This study aims to develop and apply the innovative, cutting-edge U-Pb calcite dating method, to reconstruct the time-space propagation of the seismically-active North Anatolian Fault in Greece.

Objectives (and methods)
1.To map the structural features and collect suitable calcite vein and slickenfibre material closely associated with fault surfaces developed in the carbonate rocks cropping out in the islands of Skopelos and Alonissos in the Northern Sporades, Greece (fieldtrip 1) and the islands of Samothraki and Limnos in the North Aegaen Sea (fieldtrip 2)- in collaboration with Isabelle Coutand (Dalhousie University, Canada)
2.To use U-Pb calcite dating in the laser ablation geochronology lab at the UoP
3.To collect stable isotope (C and O) and clumped isotope data to constrain the temperature, sources and potentially depths of fluid associated with the fault (in collaboration with Cedric John, Imperial)

Fieldtrip 1: Northern Sporades (10 days)Skopelos and Alonissos, May 2017, Flights £600, Accommodation £500, Ferry £100, Car hire= £500, boat hire= £500, Food=£150£2350
Fieldtrip 2: North Aegean Sea (10 days)Samothraki and Limnos, May 2018, Flights £500, Accommodation £500, Car hire= £500, Food= £150£1650
ConferenceGoldschmidt August 2017- Registration £400, abstract fee £100, Accommodation £300, Travel £100, Food £100 Total £1000
£5000

Outcomes: The results of this innovative project will, for the first time, provide direct-dating of fault movement on the NAF. The data yielded from this project will be written into at least two papers (1) showcasing the method development for directly date the timing of fault slip on seismically active faults throughout geological time; (2) highlighting the relationship between (palaeo-) seismicity and orogenic stress through geological time, which has important implications for how we understand modern seismic hazards. These papers will be submitted to leading international journals such as geology and EPSL. The funds from this project will be used to pump-prime international collaborations (between UoP, Dalhousie University and Imperial College London) and provide pilot data for writing larger grant applications to NERC, ERC and the Royal Society to expand the project to look at other seismically active faults in the Himalaya and Taiwan.