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Onine Special - Tectonic crossroads, by Sarah Beijat

Sarah (left) and Nicola, with meeting organiser Yildirim Dilek

A melange of Turkish delights - Or the misadventures of two undergrads from the University of Portsmouth who take a journey into the depths of geological research, by Sarah Biejat and Nicola Willmot Noller

Geoscientist 21.03 Online Special April 2011

Hosted by the Middle East Technical University in Ankara, a five-day Global Meeting “Tectonic Crossroads: Evolving Orogens of Eurasia–Africa–Arabia” held immense attraction for two third-year undergraduates from the University of Portsmouth. Sarah was funded by the Geological Society and the University of Texas and, with Nicola aided by subsidised student registration fees, cheap flights and accommodation, they were able to attend the event in early October.

Sarah’s interest in the event was sparked by having spent her summer mapping in Greece. For Nicola, it was an opportunity to discover more of the current thinking behind tectonic and magmatic events, and to network!

At the opening evening drinks session it was easy to be awestruck by names from the academic papers that each had read. After all, the presence of undergraduates is a rare phenomenon at such events. Fortunately rescue came in the form of Kathleen Nicoll (University of Utah) a member of the conference Scientific Advisory Committee. Propelling them forward she insisted that there was little to fear.

Sarah: “From then on it was easy; everyone was so interesting and didn’t seem to care that I was an undergraduate. They included me in their discussions making me feel that my questions were valid.”

Nicola: “In fact, I was often told that we were likely to have valid contributions, given that we were less inclined to have been influenced by the multitude of fashionable ideas that float around the academic community at any one time. We could bring them back to earth with basics – though they may have said that just to be kind!”

Highlights were widespread: the conference covered themes as diverse as “Landscape, climate and archaeological evolution”, “Magmatism and evolving orogens”, “Sedimentary basin evolution and oil fields” and “Strike-slip and transform fault tectonics”.

Memorable presentations included Mark Brandon’s proposal regarding eduction and double-sided wedges at retreating subduction zones (one to bring up in the next geodynamics lecture); Jeremy Hall’s description of the effects of the subducting Eratosthenes seamount uplifting Cyprus; and Paul Mann’s alternative perspective on the evolution of the Eastern Mediterranean, involving the subduction of a bathymetric high to generate torque and cause rapid spin of microplates (and undergraduate heads).

Robert Hall used jelly and biscuits as analogs for hard crust on a warm thin lithosphere “Especially refreshing”, says Nicola, “was his admission that he had changed his mind about the tectonics of SE Asia following further research; what he’s saying now is not what he was saying some years ago. And food analogies always work well.”

Nicola also enjoyed Carlo Doglioni’s “Asymmetric subductions in an asymmetric Earth”, which described how rotational forces influence lithospheric movement to create subduction zone geometries dependent upon the direction of subducting slabs. “It’s a subject I’d already had ideas about, so it was nice to see them elucidated in an academic environment.”

Sarah: “For me, with an interest in the Greek islands, my highlight had to be the Thursday morning sessions on Aegean Geodynamics and extensional tectonics.”

Uwe Ring portrayed a clear picture of the evolution of the Aegean region. He determined when lithospheric extension started, how much exhumation it caused and what triggered it. This was linked with the draping of the subducted slab over a 660km discontinuity causing large-scale extension and the opening of the Aegean Sea.

There was disagreement on the nature of deformation in the Menderes Massif. Klaus Gessner showed how the less dense Anatolian lithosphere had shut down subduction causing the slab to tear and initiate rollback in the Aegean. His lithospheric scale wrench zone accommodated the difference and accounted for the deformation. Douwe van Hinsbergen forcefully argued that this would have required the existence of a transform fault for which there is no evidence. His theory suggested that the Menderes Massif was already at upper crustal levels when extension began.

Wednesday was devoted to field trips. Sarah selected a challenging excursion to view various sites of Ankara mélange which, though spectacular, was perhaps not the easiest one for geology novices.

Sarah: “I saw wonderfully coloured arrays of radiolarites, serpentinites, ultramafics, mafics and pillow basalts, mixed with redeposited limestones in a highly sheared matrix. All of these crosscut by extensive diabase dykes and thrust up over recumbently folded and overturned sandstones. My ultimate impression was that in mélanges anything can happen! We saw virtually everything that can be found on and below the ocean floor all blended together, half digested and then regurgitated.

“We stood on the train track having been told to climb up the overturned sandstone if a train should come, debating at length what was of sedimentary and what of tectonic origin.”

Nicola’s trip to see volcanics and petrified forest in a newly created geopark in the Beypazar? region, Central Anatolia was much easier for an undergraduate to get to grips with.

“We stood in a wonderful rural setting below clear blue skies marvelling at the silicified branches and logs that littered a hillside near Pelitçik, remnants of a forest that may be over 18 Ma old.

“In the afternoon the volcanics of the Guvem area (10.3-9.6Ma) sparked animated discussion into the origin of the narrow columnar jointing that gave way to less regular features above.

“Finally we headed to a roadcut of laminated clays and marls filled with fossilised leaves, insects and fish. A happy half hour was spent looking for the best exhibits of which there were plenty to be found.”

By Friday afternoon heads were overflowing with visions of subduction zone polarity reversals, delaminations and slab breakoffs, rotating blocks and lower crustal flow. It had definitely been a trip worth taking, although Portsmouth tutors might well be in for some challenging questions this year.

“We’d definitely recommend the experience to fellow undergraduates who are serious about study – there’s a lot to take in – but we encountered nothing other than friendly support and encouragement from conference attendees, many of whom invited us to stay in contact. It was a wonderful experience.”