ANDYN

THE ANDES-NAZCA DYNAMIC TOPOGRAPHY EXPERIMENT

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 Obiettivo del progetto (Objective)

'In the world, there is a relative paucity of studies that correlate surface data with deep Earth processes. The main objective of this experiment is to introduce a series of observations from geology (basins, thrust belts and plateaus) to constrain mantle flow models and better understand the topographic signal generated by the mantle. We propose to test an active and natural laboratory: The Andes. The study will embrace the Andean history from Miocene to Present, the main orogenic phase of South America, and from the Amazonian foreland to Patagonia. In these regions, mismatches between orogen dynamics and basin geometries suggests mantle generated topography is an important factor. Understanding the sources of dynamic topography, its amplitude and wavelength and how they vary as the tectonic environment changes (subduction angle and rheology) will help to understand continental wavelength geoid anomalies and surface deflections, as well as large-scale basin subsidence and surface uplift, not only in the Andes but also in orogens with similar origin. I will conduct a series of regional 3-D mantle flow finite element simulations to predict surface deformation and compare to observational geophysics, lithospheric modeling (eg. residual topography) and geological data. Geology will focus on basin analyses (stratigraphy, structural reconstructions, thermo-/geo-chronology, backstripping and flexural models), supported by a compilation and reprocessing of geophysical observations (industry seismic sections, InSAR, GPS, tomography, and gravity). This study will produce databases of international interest for applied and scientific fields.'

Introduzione (Teaser)

Researchers have developed new models of how the Earth's mantle has changed by incorporating surface geology data for the first time.

Descrizione progetto (Article)

Tectonics and mantle flow are the two major driving forces of Earth's topography (surface variations). While current models are fairly accurate, there are some places where the topography predicted by the models differs from reality.

The EU-funded project 'The Andes-Nazca dynamic topography experiment' (ANDYN) aimed to improve models of mantle dynamics to better reflect the influence of geological features like basins and plateaus. Researchers used the Andes (South America) to test these models, in areas where there are mismatches between modelled topography and the real landscape.

ANDYN produced three new 3D mantle flow models that incorporate geological data. One focused on more recent times (5.3 million years ago to present), while the other two focused on the Cenozoic (66 million years ago to present) and pre-Cenozoic periods.

The project showed that since the beginning of the Cenozoic era, movement of tectonic plates alone did not account for the topography seen in the Andes. These results suggest that long-held assumptions about tectonics in the region are wrong.

Interestingly, the results of the present-day model agree very closely with the observed topography of the South American mountains and plains. The only notable disagreement was off the coast of Argentina, where a very deep basin is found.

The work of ANDYN has improved current knowledge of regions of recent tectonic movement, such as the Andes. In general, this will contribute to researchers' understanding of the how the Earth's surface changes over time.