|Beschreibung:||The purpose of this work has been to study the processes of continental extension and break-up at non-volcanic margins. In particular, we studied how extension halts leading to failed rifts. For this purpose, I have processed multichannel seismic reflection and modelled wide angle data from the Galicia Interior Basin (GIB), a failed rift located offshore west Iberia (Chapter 1, 2 and 3). Our studies reveal the structure, amount of thinning and timing of extension at the GIB (Chapter 2 and 3). We have integrated the new results on the GIB with those already existent at the rest of the margin and suggested possible causes for rift failure at the basin in connection with propagation of seafloor spreading at the final break-up margins (Chapter 3 and Outlook). Additionally, we studied how extension leads to continental break-up at non-volcanic margins of the west Iberia type. We developed a numerical model based on the seismic, petrological and chronological observations made at the segments of the west Iberia margin where continental break-up occurred (Chapter 4). We have applied this model successfully to other non-volcanic margins such as the south-west Greenland margin, the Rockall Trough and the Porcupine Basin (both located offshore west Ireland)(Chapter 5). We have also found that the differences in the initial thermal structure of the margins may lead to the differences in the structural style of continental break-up between non-volcanic margins of the west Iberia type and those showing more magmatic activity during extension (e.g. the Woodlark basin, located at the eastern tip of Papua New Guinea). Our modelling stresses the importance of the rheological consequences of the process of serpentinisation at non-volcanic margins of the west Iberia type in contrast to those of a more robust magmatic production.
|Schlagworte:||Rifting ; non-volcanic margins, failed basins, multichannel seismic reflection, wide angle data, numerical modelling , West Iberia margin, Galicia Interior Basin, crustal rheology during extension, serpentinisation, melt production
Iberische Halbinsel ; Kontinentalrand