Quantifying sedimentation in extensional basins and magmatism during continental collision

Abstract

Continental collision is one of the main tectonic processes responsible for the formation of mountain ranges and plays an important role in the overall crustal growth, i.e. in the creation of new crust. Understanding the processes operating during continental collision demands an integrated approach in which the linkage of the lithospheric-, crustal- and basin-scale processes are analyzed at various time scales. Therefore, in this thesis, I aimed to study the migration of deformation and its effect on deposition in asymmetric extensional basins and magmatism in collisional orogenic systems from basin- to lithospheric-scale. The Dinarides of Central Europe and the Betic Cordillera of SE Spain, two key areas of the Alpine - Mediterranean region are natural laboratories where such relationships were studied. A detailed, sedimentological and kinematic field study has led to a new generic sedimentological model for extensional asymmetric basins typical for the late stage evolution of an orogen. The model includes low- and high-order tectonically induced sedimentary cycles. The high-order sedimentary cycles recorded close correlation between periods of normal faulting and deposition at the scale of individual normal faults. The low-order i.e. basin scale sedimentary cycles may be driven either by extensional deformation migration or the structural reorganization following the stages of the basin development. This model is based on case studies from non-marine (Sarajevo - Zenica Basin, Dinarides) and marine (Sorbas Basin, Betic Cordillera) depositional systems. The numerical modelling of magmatic processes in subduction-collision setting emphasize the importance of rheological stratification of the continental crust on the variability of magmatism across the collisional zone. This has led to a new model explaining the migration of magmatism across the orogen by relatively strong lower crustal indentation. Numerical simulations also showed that magmatism has a strong impact on the overall geodynamic evolution of collisional zones, especially in localizing deformation and changing its style. Furthermore, the gradual change of magmatic sources during collisional stages is explained as a response to certain lithospheric-scale processes, i.e. relamination, slab detachment and eduction which followed subduction of oceanic and continental lithosphere along the colliding margins. Although the numerical modelling setup represents a simplified reality, and our models were not designed to fit a particular natural system, they do serve to better understand the collisional dynamics of the Dinarides. Additionally, the field results from the Sarajevo - Zenica Basin, help to better constrain crustal - scale processes operating during the late – and post – collisional stages in the Dinarides. Particularly, this applies to deformation styles and their migration patterns in relation to surface processes during the Neogene.