ALBERT

Description: Abstract

Description: The Central Andean orogeny is caused by the subduction of the Nazca oceanic plate beneath the South-American continental plate. In Particular, the Southern Central Andes (SCA, 27°-40°S) are characterized by a strong N-S and E-W variation in the crustal deformation style and intensity. Despite being the surface geology relatively well known, the information on the deep structure of the upper plate in terms of its thickness and density configurations is still scarcely constrained. Previous seismic studies have focused on the crustal structure of the northern part of the SCA (~27°-33°S) based upon 2D cross-sections, while 3D crustal models centred on the South-American or the Nazca Plate have been published with lower resolution. To gain insight into the present-day state of the lithosphere in the area, we derived a 3D model that is consistent with both the available geological and seismic data and with the observed gravity field. The model consists on a continental plate with sediments, a two-layer crust and the lithospheric mantle being subducted by an oceanic plate. The model extension covers an area of 700 km x 1100 km, including the orogen, the forearc and the forelands.

Description: Methods

Description: Different data sets were integrated to derive the lithospheric features: - We used the global relief model of ETOPO1 (Amante and Eakins 2009) for the topography and bathymetry. - The sub-surface structures were defined by integrating seismically constrained models, including the South-American crustal thickness of Assumpção et al. (2013; model A; 0.5 degree resolution), the sediment thickness of CRUST1 (Laske et al. 2013) and the slab geometry of SLAB2 (Hayes et al. 2018). - Additionally, we included seismic reflection and refraction profiles performed on the Chile margin (Araneda et al. 2003; Contreras-Reyes et al. 2008, 2014, 2015; Flueh et al. 1998; Krawzyk et al. 2006; Moscoso et al. 2011; Sick et al. 2006; Von Huene et al. 1997). - Besides, we used sediment thickness maps from the intracontinental basin database ICONS (6 arc minute resolution, Heine 2007) and two oceanic sediment compilations: one along the southern trench axis (Völker et al. 2013) and another of global-scale (GlobSed; Straume et al. 2019). To build the interfaces between the main lithospheric features, we compiled and interpolated these datasets on a regular grid with a surface resolution of 25 km. For that purpose, the convergent algorithm of the software Petrel was used. We assigned constant densities within each layer, except for the lithospheric mantle. In this case, we implemented a heterogeneous distribution by converting s-wave velocities from the SL2013sv seismic tomography (Schaeffer and Lebedev 2013) to densities. The python tool VelocityConversion was used for the conversion (Meeßen 2017). To further constrain the crustal structure of the upper plate, a gravity forward modelling was carried out using IGMAS+ (Schmidt et al. 2010). The gravity anomaly from the model (calculated gravity) was compared to the free-air anomaly from the global gravity model EIGEN-6C4 (observed gravity; Förste et al 2014; Ince et al. 2019). Subsequently, the crystalline crust of the upper plate was split vertically into two layers of different densities. We inverted the residual between calculated and observed gravity to compute the depth to the interface between the two crustal layers. For the inverse modelling of the gravity residual, the Python package Fatiando a Terra was used (Uieda et al. 2013) For each layer, the depth to the top surface, thickness and density can be found as separate files. All files contain identical columns: - Northing as "X Coord (UTM zone 19S)"; - Easting as "Y Coord (UTM zone 19S)"; - depth to the top surface as "Top (m.a.s.l)" and - thickness of each layer as "Thickness (m)". The header ‘Density’ indicates the bulk density of each unit in kg/m3. For the oceanic and continental mantle units, a separate file is provided with a regular grid of the density distribution with a lateral resolution of 8 km x 9 km and a vertical resolution of 5 km. The containing columns are: Northing as "X Coord (UTM zone 19S)"; Easting as "Y Coord (UTM zone 19S)"; depth as "Depth (m.a.s.l)" and density as "Density (kg/m3)"

Description: Abstract

Description: IGMAS+ is a software combining 3-D forward and inverse modeling, interactive visualization and interdisciplinary interpretation of potential fields and their applications under geophysical and geological data constrains. The software has a long history starting 1988 and has seen continuous improvement since then with input by many contributors. Since 2019, IGMAS+ is maintained and developed at The Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences by the staff of Section 4.5 – Basin Modelling and Section 5.2 – eScience Centre with strong ongoing support by H.-J. Götze and S. Schmidt from CAU Kiel. The official webpage of IGMAS+ is available at https://www.gfz-potsdam.de/igmas. Each major version of IGMAS+ is assigned with a DOI. Intermediate releases including changelog can be found at https://git.gfz-potsdam.de/igmas/igmas-releases/-/releases/.

Description: Methods

Description: In IGMAS+, the analytical solution of the volume integral for the gravity and magnetic effects of a homogeneous body relies on reducing the three-folded integral to an integral over the bounding polyhedrons (in IGMAS+, polyhedrons are constructed using triangles). The algorithm encompass all elements of the gravity and magnetic tensors. Optimized storage facilitates extremely fast inversion of material parameters and changes to the model geometry. This flexibility simplifies handling geometry changes, as the model geometry is promptly updated, and the field components are recalculated after each modification. The additional ability to invert for the geometry of the individual body interface extends the inverse modelling capabilities. Thanks to its triangular model structure, IGMAS+ effectively manages complex structures, such as the overhangs of salt domes. The software accommodates remanent and induced magnetization of geological bodies and finds application in interpreting borehole gravity and magnetics. The modeling process is guided by constrains from independent data sources, such as structural information, geological maps and seismic data, and is crucial for the genuine integration of 3D thermal modeling and/or full waveform inversion results. IGMAS+ is largely used in the creation of 3-D data-constrained subsurface structural density and susceptibility models at different spatial scales. Both large-scale models (thousands of square km) and regional (hundreds of square km), are important for understanding the drivers of geohazards. In this case IGMAS+ is versatile, capable of handling both flat (regional) and spherical models (global, when it is necessary to consider the curvature of the Earth) in 3D. Medium-scale models support studies on the usage of the subsurface as thermal, electrical or material storage in the context of energy transition. Small-scale (tens of square km) models are largely used in applied geophysics, typically in sub-salt and sub-basalt settings.

Description: TechnicalInfo

Description: List of changes for Release 1.4.8840 Added • Import of lines (#124, #188) • Interface inversion functionality (#135) • Bounding box for interface inversion (#142) • Export of quality and standard deviation values per iteration after interface inversion (#146, #171) • Nearest neighbour interpolation for empty voxels while importing voxel cubes (#158) • Special panel for empty voxel cells after importing a voxel cube (#162) Changed • Colours and line styles for fields in the 2D view (#126) • Triangulation check message corrected to Topology check (#156) • Misleading wording in the voxelization panel: "cubes" changed to "cells" (#165) • Redesign of the sectioning wizard (#44, #173, #217, #236, #242) • Title of new model wizard (#174) • Default header for imported CSV files (#219) Fixed • Incorrect 3D rendering of intersecting bitmaps with enabled transparency/alpha channel (#128, #192) • Graphical issue after deletion of the stations (#136) • Issues during interface inversion (#137, #143, #147, #151, #159, #170, #179) • Problem with voxel import while using grouping option (#141) • Exception in MarchingCubesPlugin (#144) • Problem with density geoid inversion (#145) • Problem with missing anomaly field after loading the project (#148) • Visualization of crossing triangles in the 2D view (#149) • Errors in voxelization resulting in voxels with zero density (#153) • Problem with creating a project using horizon import (#154) • Wrong effective density value in the information tab (#161, #246) • Problem with SVG export from the Multiple Cutter View (#166) • Coordinate issues while creating new project using import of horizons (#168, #169) • Wrong voxel visualization in 2D View when using non•square voxel cells (#175) • Bug with re-installation of older version on top of the newer (#176) • Incorrect calculation of the border effect in case when the density of the model units is not given in t/m3 (#178) • Wrong name for the standard deviation in linear parameter inversion, voxel effect (#189) • Error in distance unit conversion while loading voxel cubes (#190) • Incorrect vertical placement of loaded bitmaps in the Multiple Cutter View (#208) • Not updating body volume values after automatic correction of polygon orientation (#216) • Problem while loading horizons with identical points as CSV files (#218) • Incorrect parsing of headers of certain TSURF GOCAD files (#220, #221) • New body added to a model is not assigned the existing properties (#224) • Installer is not creating shortcuts on Linux (#222) • Wrong calculation of voxel effect when combined with triangulation (#227) • Bug while rendering images in the WorldWind plugin (#230) • Effective density in information tab is shown even outside of the voxel cube (#231) • Wrong application of default voxel function to the bodies deactivated during the voxel import (#232) • Voxel cube is not visible in the 2D View (#233) • Wrong assignment of the voxel cells to bodies after geometry changes (#239) • Image files with names containing space are not reloaded with project (#240) • Problem with visualization and calculation after loading voxel cubes of susceptibility type (#243) • Problem with loading projects created with earlier versions (#244) • Wrong effective density in information tab while voxel factor is not equal to 1 (#246) List of changes for Release 1.4.8707 Added • An option to change the font size of the axes and colour bars in 2D Map View (#45) • Reversed colour maps from the scientific colour map set (#45) • An option to set up manually the limits and the step of isolines or contours (#45) • An option to set up the colour bar position (#45) • A possibility to load local KML/KMZ files in the WorldWind plugin (#123) • An option in the object tree to show/hide fields in different views (#130) • An option to remove the components and fields (#131) • Added a WMS service (in the WorldWind plugin) by GFZ Potsdam based on maps.gfz-potsdam.de (#133) Changed • Flatlaf updated to 1.1.2 Fixed • All visibility settings of calculated and measured fields are synchronised for comparability (#45) • By default the colour bar for each field in 2D Maps View is placed horizontally below each panel (#45) • Rounding of the contour (isoline) labels (#132) • Adjustment of colour bar position in 2D Maps View (#125) • Sorting and storing of the list of model parameters in body manager (#122) List of changes for Release 1.4.8690 Added • 58 new themes from JFormDesginer (#113) • Possibility to select colormaps for fields and residuals from scientific colormap set (#45) • Possibility to change contours for fields and residuals Changed • Old icon in wizards was replaced with new IGMAS icon (#108) • Colormaps of the fields and residuals (#45) • Mirrored residual colorbar limits to ensure white zero values (#45) • Field rendering options are saved for each project (#45) Fixed • Wrong symbols in the license text due to encoding (#106) • Problem with license wizard after installation (#112) • Starting from icon in macOS (#107) • Issue with mouse pointer (#118) related to working sections (#35) List of changes for Release 1.4.8671 Added • A possibility to choose units other than t/m3 during voxel import (#21) • An option to perform update check (#96) Changed • GFZ logo in the starting view • License attributes (#93, #98) Fixed • Bug with wrong calculation of anomaly if the voxel density unit is not t/m^3 (#74) • Calculation of the body volumes (#32) • Exception after closing a project (#95) • Padding in the installer (#14) • Update check wrongly notified that there is a newer version (#94) • Installer link in popup update notification (#92)

Description: Abstract

Description: IGMAS+ is a software combining 3-D forward and inverse modeling, interactive visualization and interdisciplinary interpretation of potential fields and their applications under geophysical and geological data constrains. The software has a long history starting 1988 and has seen continuous improvement since then with input by many contributors. Since 2019, IGMAS+ is maintained and developed at The Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences by the staff of Section 4.5 – Basin Modelling and Section 5.2 – eScience Centre with strong ongoing support by H.-J. Götze and S. Schmidt from CAU Kiel. The official webpage of IGMAS+ is available at https://www.gfz-potsdam.de/igmas. Each major version of IGMAS+ is assigned with a DOI. Intermediate releases including changelog can be found at https://git.gfz-potsdam.de/igmas/igmas-releases/-/releases/. This is a collection DOI referring to all versions of IGMAS+. Links to each published version are redundantly available via the "Files" section and the Related Work section ("includes").

Description: Methods

Description: In IGMAS+, the analytical solution of the volume integral for the gravity and magnetic effects of a homogeneous body relies on reducing the three-folded integral to an integral over the bounding polyhedrons (in IGMAS+, polyhedrons are constructed using triangles). The algorithm encompass all elements of the gravity and magnetic tensors. Optimized storage facilitates extremely fast inversion of material parameters and changes to the model geometry. This flexibility simplifies handling geometry changes, as the model geometry is promptly updated, and the field components are recalculated after each modification. The additional ability to invert for the geometry of the individual body interface extends the inverse modelling capabilities. Thanks to its triangular model structure, IGMAS+ effectively manages complex structures, such as the overhangs of salt domes. The software accommodates remanent and induced magnetization of geological bodies and finds application in interpreting borehole gravity and magnetics. The modeling process is guided by constrains from independent data sources, such as structural information, geological maps and seismic data, and is crucial for the genuine integration of 3D thermal modeling and/or full waveform inversion results. IGMAS+ is largely used in the creation of 3-D data-constrained subsurface structural density and susceptibility models at different spatial scales. Both large-scale models (thousands of square km) and regional (hundreds of square km), are important for understanding the drivers of geohazards. In this case IGMAS+ is versatile, capable of handling both flat (regional) and spherical models (global, when it is necessary to consider the curvature of the Earth) in 3D. Medium-scale models support studies on the usage of the subsurface as thermal, electrical or material storage in the context of energy transition. Small-scale (tens of square km) models are largely used in applied geophysics, typically in sub-salt and sub-basalt settings.

Description: Abstract

Description: IGMAS+ is a software for 3-D modelling of potential fields and its derivatives under the condition of constraining data and independent information. It comes with tools for forward and inverse modelling. IGMAS+ has a long history starting 1988 and has seen continuous improvement since then with input by many contributors. Since 2019, IGMAS+ is maintained and developed at The Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences by the staff of Section 4.5 – Basin Modelling and ID2 – eScience Centre with strong ongoing support by H.-J. Götze and S. Schmidt from CAU Kiel. The official webpage of IGMAS+ is available at https://www.gfz-potsdam.de/igmas/. Each major version of IGMAS+ will be assigned with a new DOI. Intermediate releases including changelog can be found at https://git.gfz-potsdam.de/igmas/igmas-releases/-/releases/.

Description: Methods

Description: In IGMAS+ the analytical solution of the volume integral for the gravity and magnetic effect of a homogeneous body is based on the reduction of the three-folded integral to an integral over the bounding polyhedrons (in IGMAS polyhedrons are built by triangles). The original algorithm has been extended to cover all elements of the gravity and magnetic tensors as well. Optimized storage enables extreme fast inversion of material parameters and changes to the model geometry and this flexibility makes geometry changes easy. Immediately after each change, model geometry is updated and the field components are recalculated. Because of the triangular model structure, IGMAS+ can handle complex structures (multi Z surfaces) like the overhangs of salt domes very well. It handles remanent and induced magnetisation of geological bodies and was applied to the interpretation of borehole gravity and magnetics. Modelling is constrained by structural input from independent data sources, such as seismic data, and is essential toward true integration of 3D thermal modelling or even Full Waveform Inversion. Geophysical investigations may cover huge areas of several thousand square kilometres but also models of Applied Geophysics at a meter scale. Due to the curvature of the Earth, the use of spherical geometries and calculations is necessary. IGMAS+ can be used for both flat (regional) and spherical models (global) in 3D.

Description: TechnicalInfo

Description: List of changes for Release 1.3.8656 Fixed •Custom projection using GeoTools (#22) •Voxel density units (#74) •Dark/light theme selector not working for the first start (#83) •The size of windows for text input (#76) •Consistent user experience for all ptaforms (#69) •Build problem (#65) •Bug with reading "calculated (measured) Geoid" from ".station" format (#38) •Build problem (#59) •Spherical calculation settings of "Max. Length" (#37) •An error occured when section was defined with normal (0, -1) (#35) •Bug when save project button is disabled while reaching recent items directory (#4) •EPSG codes not appearing in projection lists (#28) •Multiple cutter showed anomaly field in white (#36) •Residual field is in mGal/km when the gradients are calculated in Eötvös (#36) •Wrong factor for magnetic field calculation with mT (#29) •Bug related to memory settings (#31) •Image export •WorldWind renderer •Linux executables Added •GFZ branding in installer (#14) •Calculation of body volume (#32) •GeoTools gt-referencing projection (#78) •New flatlaf design themes •Integrate update check (#43) •Notification about missing coordinate system when starting spherical approximation (#16) •2-D View icon to the toolbar •Warning for the missing projection •This changelog Changed •Migrated to latest JOGL bindings (#84) •Name of the app after installation changed to IGMAS+ (#81) •About window (#53) •Switch from JSyntaxPane to RSyntaxTextArea (#71) •Migrated to new truelicense version v4 (#56) •Using "imported" instead of "measured" for Geoid for export/import (#41) •Disabled SSL certificate validation for WorldWind tile server •Viewboard logo - GFZ logo is used now (#14) •Switched to latest jython 2.7.2b2 •Switched to java8 as minimum requirement •Switched to the latest parsii library •Swtiched to the latest proj4j library •Updated main logo •Updated installer •Version numbers will now be generated following [major].[minor].[ci_pipeline_id]-[commit_hash]-[testing]. Removed •toolbox3d dependency (#57) •Geometry inversion from installer (#33) •Unsupported cluster installer