ESR9

Project Title: The role of subduction in the formation and evolution of continental slivers and microcontinents

Supervisor: Carmen Gaina, Torgeir Andersen, Susanne Buiter

Objectives: To identify how subduction-related processes affect continental margins, and how feedbacks between inherited structures and subduction may lead to microcontinent formation. Classical scenarios of microcontinent formation refer to continental rifting followed by seafloor spreading and subsequent mid-ocean-ridge relocation that results in the detachment and isolation of continental blocks. However, several generations of microcontinents have been formed in the Iapetus and Tethys domains in the Palaeozoic and Mesozoic, and in the Mediterranean more recently (e.g. Corsica and Sardinia since the Miocene) due to slab pull and rollback, trench relocation and subduction polarity changes. To unravel the dynamic relationship between microcontinents and subduction dynamics the project will examine two cases: (1) the extended continental margin and microcontinents preserved in the Norwegian Caledonides and (2) the Baleares, Corsica and Sardinia in the Mediterranean region. The project will combine field observations with plate kinematic and dynamic forward models.

Expected Results: a) Revised kinematic models of the evolution of the Iapetus ocean and the Baltica and Laurentia margins including the estranged microcontinents; b) Quantitative kinematic restoration of the Balearic Islands, Corsica and Sardinia; c) Analogue models of microcontinent formation due to trench polarity changes; d) Numerical models of microcontinent formation due to subduction; and e) Generic models for the evolution of microcontinents (including changes in topography and subsidence) due to subduction

Academic secondment: U.Utrecht, D. Sokoutis/UR1, J.P. Brun, 6 months for analogue modelling. Industry secondment: LUNDIN Norway, 1-3 months, for geological and geophysical data interpretation (co-supervisor J. E. Lie).

Links to other projects: Coordinated laboratory work with ESR2, 3 and 6; Benchmarking numerical modelling results with ESR2; comparison of results from numerical and analogue modelling with results from ESR5, 7, 10.