Orogenesis from bottom to top – Investigating the geodynamics of mountain building using coupled thermo-mechanical-surface-process models

Postponed access: the file will be available after 2022-10-22The objective of this project is to The objective of this project is to advance our understanding of mountain building processes in different plate tectonic settings and with specific focus on the interaction between surface processes and tectonics. Three topics are investigated: 1. The factors controlling overriding plate extension or shortening in ocean-continent subduction systems. 2. The evolution of continent-continent collision orogens from small to large, their typical distribution of shortening, variable structural style, and associated controlling factors. 3. The relation between surface processes and tectonics during orogenic growth and decay and the factors controlling height, width, and longevity of collisional mountain belts. The three research aspects are investigated with the help of numerical models and comparison to natural examples. The newly developed models allow for the first time to efficiently model the coupling between tectonic deformation, erosion and deposition. Results are synthesized in published or submitted articles, provide new geodynamic relationships, ideas, and theory, and simplify understanding of mountain building on Earth. For topic 1, we use two-dimensional thermo-mechanical models, and show that back-arc extension or shortening of the overriding plate in ocean-continent subduction systems is determined by absolute plate velocities on Earth: Overriding plate movement towards the trench inhibits backarc extension and promotes overriding plate shortening, and a stable overriding plate or absolute plate movement away from the trench promote backarc extension. Additionally, a weak backarc lithospheric mantle, removed through Rayleigh-Taylor instabilities induced by the subduction process, is required for backarc extension and facilitates overriding plate shortening. Computation of driving and resisting forces during orogenesis shows near-balance of forces and explains why a weak and thinned backarc lithospheric mantle is pivotal for backarc extension and shortening. Comparison of model results with the Andes and Hellenic subduction zones corroborates that a weak and thinned backarc lithospheric mantle and absolute plate velocities determine overriding plate deformation. In topic 2, we use two-dimensional thermo-mechanical continent-continent collision models tightly coupled to a 2D surface process model and show that distribution of shortening during orogen growth follows a typical evolutionary pattern from a pro-side-dominated cold wedge to an orogenic plateau. Internal crustal loading is the main factor controlling the large scale deformation, while lithospheric pull only modulates the plate driving forces to sustain orogenesis. To first order surface processes delay orogenic growth, and modulate the structural style during growth. Utilizing a force-balance analysis, we show how inherited structures, surface processes, and decoupling between thick-and thin-skinned deformation influence the structures during orogenic growth. Comparison of generic model results with the Pyrenees, Alps, and Himalaya-Tibet shows applicability and limitations of model inferences. For topic 3, we use two-dimensional thermo-mechanical continent-continent collision models tightly coupled to a 2D surface process model and show that orogenic growth and decay depend on crustal rheology and surface process efficiency, and can be subdivided into two phases each. In growth-phase one, orogens grow primarily in height, followed by lateral growth in phase 2. Depending on surface process efficiency, phase-2-orogens can be classified into three types (Type 1, 2a, 2b): Type 1 orogens are not in flux-steady state, and are characterised by longitudinal valleys in the orogen core and low uplift and erosion rates. Flux-steady state, pre-dominantly transverse river flow in the orogen core and high uplift and erosion rates are characteristic for type 2 orogens. These orogens can furthermore be subdivided into types 2a and 2b, depending on whether the pro-side of the mountain belt produces significant thrust sheets. Based on model results, we derive an analytical scaling relationship of mountain belt growth and present a new non-dimensional number, $Be$, that describes the interaction between surface processes and tectonics during orogenic growth, and allows approximation of crustal strength and average fluvial erodibility of orogens on Earth. Finally, we use our scaling relationship and model inferences to compare to several orogens on Earth, specifically the Southern Alps of New Zealand, Taiwan, and Himalaya-Tibet. Our model inferences imply that the height of most growing orogens on Earth is controlled by the crustal strength of the foreland, and not by surface processes efficiency. In contrast, orogenic decay is primarily dependent on surface process efficiency. In decay-phase one, short-wavelength "tectonic" topography is quickly removed within few Myrs, before an effectively local-isostatic rebound creates slow decay of topography, with a timescale depending on surface process efficiency. We conclude that survival of orogenic topography for several tens to hundreds of Myrs is likely the default behaviour on Earth.Doktorgradsavhandlin

Hedge Funds and Risk Decoupling: The Empty Voting Problem in the European Union

The law must remain adaptive and responsive to the constantly changing challenges of our society and our business life. One of the most pressing challenges of the past years is the emergence of alternative investment funds, in particular hedge funds, which masterfully exploit the traditional categories of corporate law, financial derivatives, and risk management. This Article is only concerned with the first of these two forms— negative decoupling.9 It looks at the various forms of negative riskdecoupling strategies and tries to shed light on their overall desirability. Three distinct theoretical perspectives are used as an analytical framework to examine the vast challenges of risk-decoupling: (1) a classical agency costs approach; (2) an information costs perspective; and (3) a view from corporate finance. This Article argues that shareholders with hedged risk exposure do not correspond to the traditional market expectations of shareholders. Based on the insight developed from these policy perspectives, this article develops regulatory reform proposals, particularly with regard to the EU context

Zusammenprall mit einer hassgeliebten Stadt : "Im Osten war ich Drachentöter / Im Westen Wolf – doch niemals Köter": Gespräch mit Wolf Biermann über seine neuen Lieder und Gedichte

Hans-Georg Soldat interviewte im Jahre 1999 Wolf Biermann für die Berliner Morgenpost. Unter anderem zu Biermanns neuen Liedern und Gedichten, seinem Berlinbezug nach der Ausbürgerung sowie Assoziationen zum politischen Begriff der "Berliner Republik"

Keeping up with Innovation: Designing a European Sandbox for Fintech. CEPS ECMI Commentary no 58 | January 2019

In the aftermath of the 2007-09 global financial crisis, regulators in all major jurisdictions introduced significant new requirements for financial firms. Certainly justified in purpose, these regulations have increased market barriers, both directly through specific obligations, and indirectly through the sheer magnitude and complexity they involve. Regulators primarily focused on bolstering financial stability and consumer protection, while frequently disregarding their objective of promoting financial innovation. Ten years after the crisis, we believe that it is time to reconsider the appropriate balance between those objectives. In this commentary, we show how EU financial regulation may stifle the innovation of financial services. We use the example of automated investment advice, so-called ‘robo-advisors’, and we show how a proper balance between regulatory objectives could be achieved through establishing a ‘guided’ regulatory sandbox

Links Between Faulting, Topography, and Sediment Production During Continental Rifting: Insights From Coupled Surface Process, Thermomechanical Modeling

Continental rifts form by extension, and their subsequent evolution depends on the tectonic and climatic boundary conditions. We investigate how faulting, topography, and the evolution of the sediment flux during rifting are affected by these boundary conditions, in particular whether it is possible to correlate tectonic activity, topography, and sediment flux on long timescales (40 Myr). We use a thermomechanical model coupled with a landscape evolution model and present a series of 14 models, testing the sensitivity of the models to crustal strength, extension rate, and fluvial erodibility. The degree of strain localization drives the structural evolution of the modeled rifts: slow extension, high crustal strength, and efficient surface processes promote a high degree of strain localization, resulting in fewer active faults with larger offset. Overall, the magnitude of sediment production correlates with the degree of strain localization. In case of unchanged erosional power and similar amount of extension, systems with slower extension produce more sediment owing to a stronger positive feedback between erosion and fault offset. We observe a characteristic sequence of events, reflecting the morpho-tectonic evolution of rifts: the highest rock uplift rates are observed before the maximum elevation, and the highest sediment flux postdates the peak in elevation. Our results indicate that for natural systems, the evolution of the sediment flux is a good proxy for the evolution of topography, and that a time lag of 2–5 Myr between the peaks in main tectonic activity and sediment flux can exist.publishedVersio

Augmented visual, auditory, haptic, and multimodal feedback in motor learning: A review

It is generally accepted that augmented feedback, provided by a human expert or a technical display, effectively enhances motor learning. However, discussion of the way to most effectively provide augmented feedback has been controversial. Related studies have focused primarily on simple or artificial tasks enhanced by visual feedback. Recently, technical advances have made it possible also to investigate more complex, realistic motor tasks and to implement not only visual, but also auditory, haptic, or multimodal augmented feedback. The aim of this review is to address the potential of augmented unimodal and multimodal feedback in the framework of motor learning theories. The review addresses the reasons for the different impacts of feedback strategies within or between the visual, auditory, and haptic modalities and the challenges that need to be overcome to provide appropriate feedback in these modalities, either in isolation or in combination. Accordingly, the design criteria for successful visual, auditory, haptic, and multimodal feedback are elaborate