Characterization of the continental crust of Nicaragua from joint inversion modeling of gravimetric and magnetic satellite data

Abstract Nicaragua is the largest country in Central America and is located in the so-called Ring of Fire, a tectonically active zone. Its continental crust is heterogeneous and consists of a crystalline basement of the dipilto patuca microblock (DPM) and a dense crust formed by the mesquito composite oceanic terrane (MCOT). Boundaries of these crustal fragments and their extent from surface geology has not been defined. Also, the country is seated on top of important tectonic structures such as the sandino forearc basin (SFB), the nicaraguan depression (ND) and the mosquitia basin (MB). To understand and characterize the internal structure of the Nicaraguan crust, a geophysical study was carried out using different processing techniques and a joint inversion method to model satellite potential field anomalies (gravity and magnetic). The combination of these methods has allowed us to define tectonic block boundaries, characterize the geological basement, identify structural lineaments and obtain geophysical models of the upper crust of Nicaragua. The tectonic knowledge obtained will provide useful information for disaster risk reduction programs and natural resource exploration. The spectral analysis method was employed to separate regional and residual anomalies and to estimate the mean depth to the top of the gravity basement. Mean depths ranged from 22 to 7 km. Following the same analysis for the magnetic data, basement mean depths ranged from 12 to 6 km. Euler's deconvolution method was applied to the residual magnetic anomaly to determine the depth of the major magnetic features. The results show that most of the geological faults have NW–SE, NE–SW, N–S and E–W orientations, with depths ranging from 0.6 to 12.6 km. Finally, a Cross-Gradient joint inversion method was applied to invert gravity and magnetic anomalies. The 3D density and magnetization contrast models of the upper crust suggest that the crystalline basement of the Chortis Block (CHOB) and DPM may extend to more than 25 km depth into the crust. The MCOT seems to extend to a depth of 17 km. The ND has a width of 60 km and a depth of 12 to 16 km. The SFB reaches depths between 14 and 17 km. In the North Atlantic Autonomous Region of Nicaragua, intrusive bodies are interpreted to be between 15 and 20 km deep and are associated with a complex geological boundary zone between continental and oceanic crust. The MB is inferred to be between 15 and 18 km deep. Results obtained may help to understand the geotectonic context of Nicaragua, which will provide useful information to characterize the volcanic and seismic hazards in order to reduce disaster risk and explore the natural resources of the region as well.