--> PLACA4D free software: a new interactive tool for palinspastic reconstruction in 3D

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PLACA4D free software: a new interactive tool for palinspastic reconstruction in 3D


PLACA4D freeware is a new interactive tool for palinspastic reconstruction in 3D on the terrestrial sphere and Mercator projection. It is one plug-in of the software GLOBE (Ifremer), which allows dynamic representation of plate-tectonic, including all kind of georeferenced data or images (geographic information system and raster data, such geopotentiel data, geological maps). Placa4D software allows visualisation and/or modification of palinspastic reconstructions with an application to Geosciences, Paleo-oceanography, Paleoclimatology.

Placa4D allows to manipulate tectonic plate objects (TEC files) that are created by using an outline (like a coastline ascii file for example) and an information grid (elevation, gravity, magnetic, crustal ages, other) or a texture geotiff with interpretation information (geology, paleogeography, paleoclimatology, etc.). Each plate object is associated to a set of total reconstruction poles. Each pole can be defined by its age or magnetic anomaly. The relationship between anomalies and ages is provided by an ascii file that can be changed according to the user's requirements.

Placa4D also offers the possibility to associate to a tectonic plate object other graphic elements as contours, lines or points, that then can be animated through geological time. The plate could also be associated to a numerical field (DTM) model or an image (seismic section for example). Object properties, like vertical exaggeration, colouring and shading, feature colours, can be edited by the GIS interface using GLOBE functionalities.

New eulerian rotation poles between any two plates can be interactively computed using the “visual fit” method of Olivet (1978) and Bonnin (1978). This method is based on the existence on each plate of unambiguous homologous points, defined by geological or geophysical criteria that must have coincided in the moment of their formation. A simple Graphic User Interface (GUI) makes possible the selection and display of the geographical information required to derive the new rotation poles (gravity, magnetism, geologic features, DTM, etc.). For more complex plate reconstructions requiring micro-plates (for example to account for intra-plate deformation) Placa4D offers a tool to cut an existing polygon (a coastline or plate boundary, for example) that will serve to create new plate objects. Geological features that can be described by open or closed polygons or points can be digitized on screen and later on associated to a plate.

Placa4D is a simple tool to compare different kinematic reconstructions proposed for the same set of plates and it offers the possibility to make a single plot with all the plate reconstructions defined by the set of poles.

Placa4D viewer is based on NasaWorldWind and is a derivative of the IFREMER SonarScope - 3DViewer which is primarily aimed at displaying DTM and water column data. Placa4D runs on Windows, Linux and MacOS X. Placa4D is distributed with an online user manual, a tutorial and a set of example data. Placa4D is free, licensed for distribution.