IGMAS+ ? a tool for interdisciplinary 3D potential field modelling of complex geological structures.

SABINE SCHMIDT; ANIKIEV, DENIS; HANS-JÜRGEN GÖTZE; ÁNGELA MARIA GOMEZ GARCIA; MARÍA LAURA GÓMEZ DACAL; CHRISTIAN MEEßEN; CHRISTIAN PLONKA; CONSTANZA RODRIGUEZ PICEDA; CAMERON SPOONER; MAGDALENA SCHECK-WENDEROTH

Congreso; EGU General Assembly; 2020

W e introduce a new approach for 3D joint inversion of potential fields and its derivatives underthe condition of constraining data and information. The interactive 3D gravity and magneticapplication IGMAS (Interactive Gravity and Magnetic Application System) has been around formore than 30 years, initially developed on a mainframe and then transferred to the first DOS PCs,before it was adapted to Linux in the ?90s and finally implemented as a cross-platform Javaapplication with GUI called IGMAS+. The software has proven to be very fast, accurate and easy touse once a model has been established. Since 2019 IGMAS+ has been maintained and developedin the Helmholtz Centre Potsdam ? GFZ German Research Centre by the staff of Section 4.5 ? BasinModelling and ID2 ? eScience Centre.The analytical solution of the volume integral for the gravity and magnetic effect of ahomogeneous body is based on the reduction of the three-folded integral to an integral over thebounding polyhedrons (in IGMAS polyhedrons are built by triangles). Later the algorithm has beenextended to cover all elements of the gravity tensor as well. Optimized storage enables very fastinversion of densities and changes to the model geometry and this flexibility makes geometry changes easy. The geometry is updated and the gravity is recalculated immediately after eachchange. Because of the triangular model structure, IGMAS can handle complex structures (multi Zsurfaces) like the overhangs of salt domes very well. Geophysical investigations may cover hugeareas of several thousand square kilometers but also models of Applied Geophysics at a meterscale. Due to the curvature of the Earth, the use of spherical geometries and calculations isnecessary.The model technique is user-friendly because it is highly interactive, operates ideally in real-timewhilst conserving topology and can be used for both flat (regional) and spherical models (global) in3D. Modeling is constrained by seismic and structural input from independent data sources and isessential toward true integration of 3D thermal modeling or even Full Waveform Inversion. We areclose to the demand for treating all geophysical methods in a single model of the subsurface andaim of fulfilling most of the constraints: measurements and geological plausibility.We demonstrate the flexibility of the software by modeling: (1) the southern segment of theCentral Andes which is designed to assess the relationship between the characteristics of theoverriding plate and the deformation and dynamics of the subduction system; (2) the SouthCaribbean margin which defines the two flat-slab subductions of the Nazca Plate and theCaribbean Plate, with variable mantle density distribution implemented by voxels; (3) the NorthPatagonian Massif Plateau in Argentina which provides insight into the main height differencesbetween the plateau and the surroundings; and (4) an Alpine model which interrogates thestrength of the lithosphere at different locations through the Alps and their forelands.