Numerical modelling of the topographic response of subduction initiation

Collisions of tectonic plates represent some of the world's most amazing topography such as: the Alps, the Himalaya and the Pyrenees for example, as well as hotspots of seismicity. These collision zones, or subduction zones, produce changes in the topography around these active collisions. Thus topography around these active collisions is very dynamic, in some cases the result is mountains above, but in other cases, new basins are formed in the wake of the collision zone moving, in some cases between the mountains themselves. The sedimentary basins formed, for example the Ainsa Basin in the Spanish Pyrenees, allow for the direct observation of structures analogue to the ones found on the North Sea, where a substantial part of the Norwegian oil exploration occurs. By understanding how these basins evolved since the deposition of the sedimentary units and during the evolution of the oil system, with regard of the formation of reservoir, seals and maturation of the present organic matter, better choices regarding oil and gas exploration can be made. A framework for the study of these changes in the structure of geological systems will be created by applying new technologies and developing new workflows. This framework will enable a better understanding of the evolution of systems that are known to contain either hydrocarbons suitable for exploration or geological analogues. At the end of 2017 the project underwent some modifications in the study areas and methods. However, it is still in the scope of the application of computer simulations to the evolution of geological settings, namely the deformation of sedimentary basins and its influence on the prospectivity. While working on the project it was found out that another important subject to be approached in this project is the reconstitution of the margins associated within tectonic processes. This bear relevance in the oil and gas exploration industry as the comprehension of the evolution of these basins can relate to better and more accurate exploration decisions. The new study is primarily focused on the Ainsa sedimentary basin, a structure that was rotated approximately 90 degrees from its original position due to the changes in tectonic regimen during the formation of the Pyrenees, which are a consequence of the convergence of the Iberian and Eurasian plate. The reconstruction of this structure will be supported with software developed at Kalkulo, with the objective of providing some real case usage of the developed software, as well as providing feedback and creating methodologies that can improve the product and its usage. Lateral movements of geological structures will be reconstructed with resource to 4D Plates, and numerical models will be used to complement the vertical movements.

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The initiation of subduction remains a major unresolved question in geodynamics. Theoretical studies have highlighted the complexity of the processes involved. Critical parameters resulting in subduction are debated, but it is commonly accepted that zones of lithospheric weakness are required. Particular attention will be paid to the topographic response during and after the onset of subduction as it provides means for validating modelling results through the rock record of uplift, erosion, and sedimentation, and current topography. These changes in in the geological contexts also heavily influence the several comprising components of oil systems. By analyzing smaller scale compressional settings and the influence on hydrocarbon bearing systems, with focus in the reservoirs particularly, valuable information can be obtained to better understand analogues worldwide. One very important lithology for reservoirs are turbiditic sequences. The Ainsa basin, located in the Spanish Pyrenees, is one of the prime study candidates, due to the very thick sedimentary sequences of this type and also the degree of deformation associated.