TOPOMOD will focus on cross-disciplinary projects (Table 1), which al address the fundamental question “How does the Earth’s surface interact with deep crustal and mantle processes to shape topography?”, by selecting key areas as natural laboratories and integrating new developments in geochemistry, seismology, laboratory, theoretical and numerical modelling from the mantle scale to the river valley scale. To strengthen the multi-disciplinary approach, we design the work packages more on process understanding rather than on methodology development. Each WP is composed of a series of complementary subprojects, focusing on different aspects of the approached problem.

Each research project involves at least two institutions and will be co-supervised by senior scientists from different institutions, including one industrial partner. Collaboration between different research projects will be enhanced, ensuring mutual exchanges of ideas and know-how.

The main scientific questions, research methods, and projects are organized within two “scientific work packages” (Table 1; details on milestones, deliverables and a tenptative schedule in section B.2.1):

WP1: Shaping the Earth’s surface: shallow and surface contribution.

Research projects in this WP aim to gain understanding on the processes leading to the contribution of shallow and surface processes to the topography of the earth surface. How do continental interiors react to collision at plate boundaries? How does fault zone evolution affect hill slope morphology in bedrock landscapes? How does topography react to earthquake and fault zone displacement? What is the sensitivity of early stage thrust wedges and salt diapirs to surface processes?


Topographic evolution of growing mountain belts.
Supervisor: N.Hovius (Cambridge) and S. Willett (ETH)

Does emergent submarine topography control the subsequent subaerial evolution of mountain topography? How important is the onset of orographic rainfall in the competition between tectonics and erosion, and how is this process reflected in topography? How does the progressive exposure of basement rocks affect the erosional flux from a mountain belt? This project will investigate the topographic evolution of growing mountain belts during emersion from sub-marine to aerial condition through observational and modelling studies in a two-way feedback loop. The (submerged) topography of selected examples of active belts will be studied and framed within the context of records of deformation, precipitation and erosion. Numerical modelling the evolving landscape will be performed to accurately represent the physics of drainage basin evolution.


Multiscale, multidimensional deformation patterns of continental interiors: Simulation, analysis – decoding?
Supervisor: O.Oncken/ M.Rosenau (GFZ) and F. Funiciello (Roma TRE)

How does seismotectonic feedback work in continental interiors, i.e. how does permanent deformation accumulate throughout seismic cycles and what does crustal structure tell us about earthquake behavior? Can the spatiotemporal earthquake pattern in continental interiors be described in terms of time-dependent probability theory and what are the limits of earthquake prediction? The overarching goal of the project enable us to better understand the spatiotemporal pattern of seismotectonic deformation in continental interiors with a focus on short-term, hazard-related issues. Analog models will include viscoelastic and elastoplastic rheologies. Particle image velocimetry will be used to monitor the model evolution. Spatiotemporal analysis will help to decode the expected multiscale and multidimensional deformation pattern with the aim to better understand the related hazards at human time scale and the intrinsic limits of prediction.


The structure, mechanics and petrophysical properties of active fault zones in siliciclastic sediments
Supervisor: F. Rossetti, F. Storti (Parma) and N. De Paola (Durham)

Understanding the structure, deformation mechanisms and physico-chemical (transient and long-term) properties of active fault zones from seismogenic regions is an essential prerequisite to link regional tectonics to earthquake nucleation and the seismic cycle in the brittle upper crust. By means of multidisciplinary approach that integrates field studies with laboratory investigations, the research aims at characterizing the architecture and evolution of mature fault zones in clastic sediments by acquiring a multidisciplinary data set (structural, microstructural, mineralogical, grain size, grain shape, mechanical properties, permeability, porosity) in fault zones in the Central Iran. Central Iran, with its exceptional exposures and well-documented seismogenic fault arrays, offers a ideal site to perform this research. Multivariate statistical analysis of the collected multidisciplinary datasets will allow to derive empirical correlation relationships (scaling laws) and define the rheological parameterisation of the different fault zone types, in order to provide predictions on mechanical behaviours (frictional properties) of fault zones and fault systems as function of rock type, fault geometry, and fault slip. Modern analytical and laboratory techniques like digital mapping, petrophysical modelling, laser diffraction particle size analysis, optical particle morphometry, friction experiments and triaxial permeability measurements, will be routinely used in this project.


Interaction between tectonics and surface processes in the Zagros Mountains.
Supervisor: S. Castelltort (Geneva),  B. Kaus (Mainz), P. Yamato (Rennes I)

In many cases, the structures in fold and thrust belts have a regular spacing. What controls this spacing and how it is related to the rheology of the crust, however, is incompletely understood. We will use novel 3D numerical models of deformation and erosion and laboratory models to understand the coupling between tectonic and surface processes in folds-and-thrusts belts.
The Zagros Mountains, with their exceptional exposure and preservation, represent a unique opportunity to test the competition between deformation and surface processes at the upper crustal scale. The outcome of this competition potentially dictates the pattern of surface deformation and the routing of water and sediment from mountains to basins. Collaborations with ESR1, ESR6 are essential to formalize a general model for interaction between tectonics and surface processes in convergent settings.


Suture zone inversion during back-arc extension with application to the Aegean.
Supervisor: J.P. Brun (Rennes I), F. Gueydan (Montpellier) and X. Fort (G.O. Logical Consulting)

Geodynamic research carried out in the eastern Mediterranean area has revealed that the accretion of continental blocks of limited size gave birth to short-lived mountain belts rapidly destroyed by extension following slab rollback. During this process, the subducting continental crust detaches from its lithospheric mantle and returns back to surface as a direct function of trench retreat and resulting back-arc extension. Put another way, the suture zone that results from the closure of an oceanic domain followed by the accretion of a continental block becomes inverted during back-arc extension resulting in a normal-sense shear zone, flat-lying atop the exhumed rocks. It is the core of the present project to identify the geological and mechanical processes that control the inversion of a suture zone located between two continental units. In the Aegean, the closure of the Vardar ocean was first followed by crustal thickening, from late Cretaceous to mid-Eocene, and since then by back-arc extension that accommodated a trench retreat of about 700 Km. The Vardar suture zone (SZ) and more particularly its hanging wall (the Serbo-Macedonian domain), where its geological history is recorded, provides an outstanding natural example for the present study.


Links between anomalous topography and large-scale tectonics in southern India.
Supervisor: J.P. Burg (ETH), and S. Cloetingh (Amsterdam)

This project aims at understanding the long term response of a continental lithosphere submitted to far-field compression (to be complemented, compared and integrated with results of ERS4).
Combining quantification of surface topography, with laboratory and numerical modelling of mountains and lowlands anomalies over continental distances, we will be able to constrain critical processes affecting the lithosphere-asthenosphere system. Insights on the local state of stress of the lithosphere will be gained, with important implications for the seismic hazard in regions presumed to be seismically quiet, although disastrous earthquakes have occurred against any scientific expectation. This latter aspect comes in synergy with ESR2. Our case study concerns the interactions between India-Asia collision, recorded compression in the Indian Ocean and the topography of southern India.


Exploring the topography time scale in volcanic rifts.
Supervisor: T. R. Walter (GFZ) and V. Acocella (Roma TRE)

Stripmap SAR data analysis and interferometric processing will allow locating zones of active deformation, and isolate those and their sources within analytical optimization routines, however linkage between this short time analysis and the longer time scale deformation and magmatism is lacking. The aim of this project is to explore the time dependence of topography in magmatically and tectonically active rift systems by combined radar interferometry (InSAR), elastic dislocation and experimental modelling. In particular, through spatial correlations of the deformation areas and their sources

(e.g. magma intrusions) the links of the short-term to the long-term established topography (e.g. rift valley) will be explored. Experimental modelling will allow including such sources and identify similarities and differences to the observable topography, which may be affected by shallow mass mobilization or hitherto not appreciated time-dependent mechanisms.

WP2: Shaping the Earth’s surface: the deep contribution.

Coord. M. Fernandez (Barcelona), and D. Sokoutis (Amsterdam)

The Research projects in this WP will gain understanding on the contribution of deep processes to the topography of the earth surface. The main scientific questions are: how do mountain belts form? What is the role of pre-existing rheological layering on the shape and topography of convergent belts and extensional basins? What is the contribution of the upper mantle in topography and landscape evolution? Can we quantitatively constrain the interplay between mantle dynamics, tectonic uplift, erosion and exhumation?


Mechanics of faulting and exhumation of metamorphic rocks.
Supervisor: F. Gueydan (Montpellier), J.P. Brun (Rennes I) and D. Sokoutis (Amsterdam)

Subduction offers a simple and widely accepted mechanism for the burial of crustal rocks down to mantle depths. However, their return to the surface is still poorly understood. This project aims at advancing our understanding of the mechanics of exhumation processes by combining field work, analog and numerical modelling. Fieldwork would permit to identify the main structural features related to exhumation deformation from the study of field-cases in the high-pressure metamorphic belts of the Mediterranean. In particular, the mechanics of intense strain localization necessary to constrain the vertical displacement of deeply buried rocks will be studied by structural mapping in HP nappes, microstructural studies gathered with petrology and geochronology. Finally, numerical models will be used to quantify key parameters for the shearing off of continental/oceanic units during subduction.
Strong backgrounds in structural geology, mapping (GIS) and tectonics are necessary. Some backgrounds in petrology, geochronology and modelling are appreciated but not exclusive


Rheological and Structural Inheritance: Key Players in the Tectonic Evolution of Intraplate Deformation?
Supervisor: D. Sokoutis (Amsterdam) and J.P Burg (ETH)

Rheological and tectonic modelling studies indicate that the 3D rheological structure of the lithosphere plays an important role in the localization, the style of deformation and the distribution of heterogeneous intraplate deformation. This project aims to improve the understanding of the 4D processes that have led to the formation of intra-plate mountain chains (i.e. Pyrenees, the Spanish Central System, the Caucasus). More in general, the objectives are: (1) to understand the interference pattern of short and long wavelength deformation as a function of the location of weak zones (crust versus mantle) within the lithosphere and its bearing on dynamically supported topography; (2) to gain insight in the kinematic and geometric consequences of oblique shortening of inherited weak zones within continental lithosphere. The research objectives will be achieved through advanced analog and numerical modelling as the broader tectonic controls on lithosphere shortening and topography development provide an assessment of the driving mechanisms. Results of these models will be compared to seismological observations (ESR10).


Seismic characterization of intracratonic orogens.
Supervisor: R. Carbonell (Barcelona) and F. Storti (Parma)

Europe offers a unique opportunity for the characterization of intracratonic orogens, in particular with the Iberian Peninsula, the Spanish Central System and the Iberian orogen. The knowledge of the deep structure of the crust allows prediction of isostatic balancing and topographic response as recently realized for the Urals in the frame of Europrobe. This project propose to study the high resolution structure of intracratonic orogens within Iberia and Italica peninsulas, where deep seismic reflection images have been acquire, with the aim to put fundamental constraints on the nature and structure of the crust in ancient and actively deforming regions. Comparison to laboratory and numerical models (ESR9) will help to constrain the role of different physical processes on the structuring of intracratonic orogens.


Dynamic modelling of magmatism after continental collision.
Supervisor: J. van Hunen (Durham) and A.Villasenor (Barcelona).

Unlike for ongoing subduction processes, the appearance of volcanism at collision zones is not well understood, and various mechanisms for post-collisional magmatism (i.e. lithospheric delamination, slab detachment, metasomatism and chemical alteration) have been suggested. This project aims to form a better understanding of the key processes leading to collision zone magmatism. In particular, the project combines geodynamic models of continental collision and geochemistry of any associated magmatism with available geochemical, tectonic, topographic, tomographic observations, and thereby will provide new insight in one of the most important but also complex geodynamic processes on Earth. Our specific objectives are to quantify: 1) the correlation between post-collisional magmatism and the distribution of key characteristics related to this magmatism (volatiles, temperature, composition); 2) the vigour of the geodynamic mechanisms proposed to generate post-collisional magmatism; 3) their correlation with the observed timing, location, duration, amount, and geochemical signature of any post-collisional magmatism.


Mantle characterization and dynamic topography.
Supervisor: M. Fernandez (Barcelona) and C. Faccenna (Roma TRE).

The main questions to be addressed in this project are to separate the chemical and thermal signatures of the mantle density and to establish their separate contribution to dynamic topography in the Alpine-Mediterranean region.

The goal is to calculate the expected dynamic topography using a new refined approach to define the thermo-chemical parameters of the mantle. The original methodology is based on the integration of regional observables (geoid, gravity and elevation) with heat flow data and seismic constraints, together with chemical composition of mantle rocks from outcrops or xenolith suites to calculate densities at different P-T conditions and elastic properties (Vp and Vs) by using a self-consistent thermodynamic approach. Results will be compared to seismic tomographic models (ESR 10) and to results of independent analytical, numerical and laboratory models.


Lithosphere dynamics and topography contributions from the deeper mantle.
Supervisor: J. van Hunen (Durham) and A. Villaseñor (Barcelona).

To first order, the mantle plays a passive role in the dynamics of plates, as evidenced by plate kinematics.

But locally, in particular in plate interiors, plate-mantle interaction can be responsible for significant topographic effects and lithosphere dynamics that are difficult to attribute to plate tectonics, with the Hawaiian hotspot as the most obvious example. In this project we propose to examine the various mantle contributions to lithosphere dynamics and topography. In particular, we will examine instabilities of lithospheric roots and their topographic consequences due to large-scale mantle processes, such as mantle hydration (e.g. from slabs), mantle plumes and super-swells. By combining numerical models of plate-mantle interaction with geochemical, topographic and tomographic observations, we aim to constrain the role of the upper mantle in continental intra-plate dynamics. Results will be compared to seismological data (ESR12), and results of independent analytical, thermo-chemical and laboratory models (ESR12., ER1).


Slab interactions during the closure of the Tethys: control on the evolution of the Meso-Cenozoic Mediterraenean orogenesis
Supervisors: C. Faccenna and F.Funiciello (Roma TRE), B. Guillaume (Rennes I).

During its opening and progressive closure, the Tethys oceanic plate formed and dissected into smaller basins. The progressive convergence between Africa and Asia provided a restraining environment for Mediterranean subductions, favouring and possibly forcing the interactions of slabs, now imaged in the mantle. Similarly, strong rotations and curvature of the peri-Mediterranean collisional chains are recorded throughout their Meso-Cenzoic evolution. This project will investigate the feedback between the slab interactions in a restricted mantle and the collisional processes at the surface. Analogue and numerical modelling will be performed to understand characteristic processes, time- and length-scales of such interactions, and the resulting control on the stress and strain at the convergent margins during collision. The outcome will underpin our interpretation of the complex morphology and evolution observed in chains as the Alps-Apennines and the Carpathians.


Unraveling the deep origin of topography: insights from modeling.
Supervisor: F. Funiciello (Roma TRE), L. Husson (Rennes I).

Contrasting models have been proposed to constraint the topography expected over subduction zones and plumes. Uncertainties derive from the lack of knowledge on the rheological and thermo-chemical structure of the lithosphere and its coupling with the underlying mantle.

This project aims to constrain topography over a wide range of geodynamic contexts using observables from key regions and modelling. Our work will involve fluid-dynamic tank experiments, supported by an analytical formulation and numerical model. Natural data of previously identified key dynamic deflections will serve to evaluate the correspondence between models and real Earth.


Evolution of oblique continental rifting: comparison through experimental modelling and analysis of the Main Ethiopian Rift natural laboratory.
Supervisor: D. Sokoutis (Amsterdam) and G. Corti (Firenze).

Continental rifting represents one the most important geodynamical processes affecting the lithosphere-asthenosphere system.

Recent work points out that the evolution of continental rift systems such as the Ethiopian one result from the interplay between large-scale plate kinematics and local body forces. This project aims contributing to this problem by investigating the evolution and kinematics of the fault pattern in specific areas of the Ethiopian Rift system and comparing them with specifically designed laboratory experiments. The above approaches are complementary and their comparison will provide independent information on the evolution of faulting, long-term kinematics, thinning and magma production during deformation.

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