The 100 km wide Mérida Andes extend from the Colombian/Venezuelan border to the Caribbean coast. To the north and south, the Mérida Andes are bound by hydrocarbon-rich sedimentary basins.
This mountain chain and its associated major strike-slip fault systems formed by the oblique convergence of the Caribbean with the South American Plate and the north-eastwards expulsion of the North Andean Block in western Venezuela. In 2013, the Integrated Geoscience of the Mérida Andes Project (the GIAME project) was initiated to image the Mérida Andes on a lithospheric scale and to develop a dynamic model of their evolution by integrating wide-angle seismic, magnetotelluric and potential field data.
Magnetotelluric (MT) dataset was acquired in 2015 along a 240 km long profile across the Mérida Andes.
MT studies of orogens often reveal complex resistivity structures, typically associated with active deformation and characterized by high electrical conductivity zones. Fluids in fault systems and fluids derived from remineralization reactions of hydrous minerals often characterise high conductivity in active tectonic regimes. Cruces-Zabala et al. (2020) identified conductive zones with up to 10 km depth for the Maracaibo Basin and 5 km for the Barinas - Apure Basin. The Mérida Andes are charaterized by high resistivity separated by several conductive anomalies that corelate spatialy to the fault systems at the surface. A conductive zone a great depth (>50km) was identified as a projection of the detachment surface of the Trujillo Block to the east.
This data publication encompasses a detailed report in pdf format with a description of the project, information on the experimental setup, data collection, instrumentation used, recording configuration and data quality. The folder structure and content of the data repository are described in detail in Ritter et al. (2019). Time-series data are provided in EMERALD format (Ritter et al., 2015).
The data set includes the digital image correlation of 16 dextral strike-slip experiments performed at the University of Massachusetts at Amherst (USA). The DIC data sets were used for a machine learning project to build a CNN that can predict off-fault deformation from active fault trace maps. The experimental set up and methods are described with the main text and supplement to Chaipornkaew et al (in prep). To map active fault geometry and calculate the off-fault deformation we use the Digital Image Correlation (DIC) technique of Particle Image Velocimetry (PIV) to produce incremental horizontal displacement maps. Strain maps of the entire region of interest can be calculated from the displacements maps to determine the fault maps and estimate off-fault strain throughout the Region of Interest (ROI). We subdivide each ROI into five subdomains, windows, for training the CNN. This allows a larger dataset from the experimental results. The data posted here include the incremental displacement time series and animations of strain for the entire ROI.
We document the evolution of two 15° strike-slip restraining bends within wet kaolin. Computer-controlled stepper motors displace one half of the split-box apparatus at a constant rate of 0.5 mm/min to induce dextral faulting in a 2.5 cm thick layer of wet kaolin. The basal plate discontinuity has a 15° bend with a 2 cm stepover distance. Prior to any loading we cut a vertical fault surface that follows the basal plate discontinuity into the wet kaolin with an electrified probe and wooden template.
This dataset includes video sequences depicting the evolution in map view and lateral view of 7 analogue experiments studying mantle-scale subduction systems. The experiments are performed under a natural gravity field and are designed to understand the role of convergence obliquity on upper plate deformation and partitioning, with a particular emphasis on the role played by lithospheric inherited structures on the development of sliver tectonics.
All experiments were performed at the Laboratory of Tectonic modelling of the University of Rennes 1 (France). The experimental set-up corresponds to a lithosphere and sub-lithospheric upper mantle system. The lithospheric plates are simulated with PDMS silicone (Polydimethylsiloxane Silicone) with different viscosities and densities, and the upper mantle with glucose syrup. In particular, for the overriding plate, we simulate the presence of a weaker volcanic arc that can eventually be decoupled from the forearc by a pre-existing discontinuity. The materials are placed into a Plexiglas tank, where the impermeable bottom of the tank represents the 660 km discontinuity. The subduction is initiated by manually forcing the slab into the mantle and it then evolves under the combined effects of internal buoyancy forces (slab pull) and external boundary forces. The subducting plate is pushed toward the trench at a constant velocity of 1.5 cm/min while the overriding plate is maintained fixed during the duration of the experiments.
The evolution of the experiments is monitored by DSLR cameras (24 Mpx) taking pictures every 30 seconds at the top and on one side of the experiments. Pictures are then assembled into video-sequences. The scale bar, with black & white rectangles corresponds to 10 cm.
The set of experiments consists of one reference model (MODEL-01) with orthogonal convergence, and six models with oblique convergence (Table 1). Among these models, three do not embed a pre-existing lithospheric discontinuity in the overriding plate (MODEL-02, MODEL-03, and MODEL-04) while the three other (MODEL-05, MODEL-06, and MODEL-07) have such a discontinuity. For the models with oblique convergence, we vary the angle between the convergence direction and the trench from 80° (MODEL-02 and MODEL-05) to 60° (MODEL-03 and MODEL-06) and 50° (MODEL-04 and MODEL-07).
For details on the experimental set-up, and interpretation of the results, please refer to Suárez et al. (submitted to Tectonophysics) to which these data are supplementary material.