Geofísica

Archaeological evidence of pre-colonial indigenous villages are scarce in the Amazon region. Normally, wood decomposes quickly in the ground. However, in the case of stilt houses, the archaeological materials can be well preserved underwater or buried in sediments below waterbodies. The main objective of this work is to advance the understanding about the archaeological stilt village at the Formoso Lake in the Maranhão wetland, eastern Brazilian Amazon. We applied Ground Penetrating Radar (GPR) and Side Scan Sonar (SSS) for this underwater archaeological investigation.

Only a limited number of geodynamic numerical models have been successful in simulating both asymmetric and ultra-wide (>500 km) rifted margins. In this paper, we present a comprehensive suite of 72 thermo-mechanical geodynamic numerical simulations of rifting. These simulations revealed the impact of initial crustal thickness, variations in the ratios between the upper and lower crusts, rift velocity, structural inheritance, and shear heating on the asymmetry and width of conjugate rifted margins.

The necessity to reduce carbon emissions to mitigate climate change is accelerating the transition from fossil fuels to renewable energy sources. Specifically, hydropower has emerged as a prominent and safe renewable energy source but entails reservoir-triggered seismicity (RTS). This phenomenon causes significant challenges for safe reservoir management. Irapé, in Brazil, is a prominent RTS site where seismicity surged after reservoir filling, with a maximum event of magnitude 3.0 in May 2006, just 6 months after the start of reservoir impoundment.

Small-scale mining (SSM) is responsible for almost all the production of non-metallic minerals in the world and represents around 80% of the mining in Brazil. The lack of direct geological information increases the level of uncertainty associated with the exploratory process, compromises mine planning, limits mineral extraction, and contributes to maximizing environmental issues.

Earth’s magnetic field exhibits a dominant dipole morphology. Notwithstanding, significant deviations from the dipole are evident today, particularly the South Atlantic Anomaly (SAA), characterized by anomalously low-field intensity and high directional variability, diminishing the field’s shielding effect. To assess the persistence of SAA-like features over multimillion-year scales, we combine paleomagnetic data from Trindade Island (20°30’S, 29°22’W) with an evaluation of paleosecular variation (PSV) over the past 10 Myr.

To investigate the lithospheric seismic structure of southern South America beneath the Paraná, Chaco-Paraná, and Pantanal basins, we measure two distinct sets of dispersion curves of Rayleigh waves: the first corresponds to 25,986 phase velocity dispersion curves in the period range 5–50 s, extracted from cross-correlation of the ambient noise between pairs of stations and thus sensitive mainly to crustal structure; the second set is derived from group velocities extracted from earthquake recordings, resulting in 33,888 dispersion curves with periods ranging from 8 to 200 s, allowing us to

The regional-residual separation of gravity anomalies in crustal and mineral exploration was a graphical-based procedure before the advent of fast digital computers and the need for more efficient algorithms to process large data sets. However, since requiring the supervision of an experienced interpreter, the results, once obtained with graphical procedures, are often accepted as second to none in producing anomalies with geologic significance.

The thickness, temperature and mechanical strength of the lithosphere vary greatly across South America and have controlled tectonic and magmatic processes during its evolution. Here, we introduce a new tomographic model of South America’s lithosphere and underlying mantle, SACI-24, and analyse this and other state-of-the-art models together with other geological and geophysical data. The new model is obtained by waveform inversion of surface, S and multiple S waveforms globally, but is optimised for South America and the surrounding oceans.

During the Jurassic and Early Cretaceous, Earth's magnetic field experienced a high frequency of polarity reversals. This hyperactivity period is followed by a ∼38 Myr prolonged period of stable normal polarity from the Aptian until the Santonian, known as the Cretaceous Normal Superchron (CNS; chron C34n, from 121.4 to 83.65 Ma). However, the CNS might have been characterized by more variability than previously thought, but the current database is uneven in its spatial and temporal distribution.