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A detailed structural analysis of the fracture network exposed in the Jurassic strata is used to reconstruct the Lusitanian Basin's brittle tectonic history related to the Meso‐Cenozoic paleostress trajectories of the Iberian plate. Structural analysis is made by high‐resolution virtual outcrop models and orthophoto mosaics, along with information obtained in the field. The paleostress regime is determined based on the fault‐slip inversion method. Structural features are predominantly NNE‐SSW, NE‐SW and NW‐SE‐trending extensional fractures, including joints, veins, normal faults, and ~E‐W‐oriented strike‐slip faults. These structures remained active in the early basin evolution and were repeatedly reactivated by shearing and contraction. The chronological succession and paleostress reconstruction revealed three tectonic regimes (i) NE‐oriented extension, (ii) NE‐oriented strike‐slip and (iii) NW‐shortening. The first stress regime was driven by the North Atlantic rift propagation in the Iberia's west and northwest margins in the Late Jurassic–Early Cretaceous. The younger stress states involve reactivation and inversion of pre‐existing fractures by Africa–Europe convergence since the Late Cretaceous. The findings are consistent with the regional stress field which the Iberian plate has experienced since the Meso‐Cenozoic. [ABSTRACT FROM AUTHOR]

Implicit modeling has experienced a rise in popularity over the last decade due to its advantages in terms of speed and reproducibility in comparison with manual digitization of geological structures. The potential-field method consists in interpolating a scalar function that indicates to which side of a geological boundary a given point belongs to, based on cokriging of point data and structural orientations. This work proposes a vector potential-field solution from a machine learning perspective, recasting the problem as multi-class classification, which alleviates some of the original method's assumptions. The potentials related to each geological class are interpreted in a compositional data framework. Variogram modeling is avoided through the use of maximum likelihood to train the model, and an uncertainty measure is introduced. The methodology was applied to the modeling of a sample dataset provided with the software Move™. The calculations were implemented in the R language and 3D visualizations were prepared with the rgl package. [ABSTRACT FROM AUTHOR]

Abstract Geological structures influence the formation and evolution of sedimentary rocks. The Minas do Camaquã fault zone is a primary structure of the Camaquã Basin, controlling the uplift of the ore-bearing units of the Santa Bárbara Group. To the south of the Camaquã River, the fault zone deforms alluvial and eolian sequences attributed either to the Santa Bárbara or Guaritas groups. In this study, a facies and petrographic composition and diagenetic analysis are presented to understand the evolution of the fault zone. Facies analysis was accomplished using high-resolution orthophoto mosaics and field surveys. Seven sedimentary facies were defined, grouped into three facies associations. Facies associations correspond to a succession of climate-influenced depositional environments. The transition from humid to dry conditions occurs from a fluvial (facies association 1) to eolian environments (facies association 2). These deposits are overlaid at the top by a high energy environment deposits characterized by amalgamated gravelly and sandy bodies, corresponding to an alluvial environment (facies association 3). Despite a small compositional variation, sandstones present a continental block provenance which may be related to mixed anorogenic or orogenic provenance. Diagenetic features are similar in the three facies associations, suggesting the same burial history for the sedimentary deposits separated by the fault zone. The Minas do Camaquã fault zone in the study area is an intraformational structure, as analyzed sequences are attributed to the Guaritas Group, implying a relatively high degree of deformation late after its deposition. Highlights • Fault zone separates steeply inclined from horizontal sequences. • Three facies associations were interpreted from field and remote sensing data. • Sandstones detrital composition indicates continental block and mixed provenance. • Fault zone does not limit diagenetic variations suggesting a single burial history. • Units separated by the fault zone correspond to the Guaritas Group. [ABSTRACT FROM AUTHOR]

This work presents a Gaussian process model (a Bayesian derivation of kriging) for the interpolation of structural field data (dip and strike measurements). The structural data are treated as the directional derivatives of a latent potential field. The latent field's isosurfaces characterize the general structural trend in a region, and the predictive variance can be used as a measure of uncertainty. The model's parameters are optimized via maximum likelihood, avoiding the need for a variogram analysis. The model is tested using the orientation vectors of metamorphic foliation in meta-volcanic rocks of the Passo Feio Metamorphic Complex, in southern Brazil. An open-source implementation is available. • A potential field is modeled from orientation data alone with the Gaussian process. • Structural surfaces correspond to isovalues of the modeled field. • Covariance parameters are trained through maximum likelihood. • Open-source implementation available. [ABSTRACT FROM AUTHOR]

This paper brings an assessment of ex situ geoheritage elements, as well as of geodiversity-related contexts and identities for the COREDE Campanha territory of the 'southern half' of Rio Grande do Sul State, Brazil. The ex-situ elements are fossils of extinct animals of Permian (amphibians and para-reptiles) and Pleistocene (mammal megafauna, especially ground sloths) ages. Curious or interesting geoheritage contexts, such as the coal-forming Permian wetlands, an oceanic lithosphere slab, or very ancient craton areas have also been highlighted. Finally, the paper approaches the artisanal gold miners' identity and the metallic ore mining memory, along with their rich built cultural heritage. By means of an adequate interpretation, such features can be added to geosites within a broad geotourism strategy for the territory of COREDE Campanha. [ABSTRACT FROM AUTHOR]

This paper presents a qualitative inventory of 'complex areas'-type geosites within the territory of the COREDE Campanha, in the so-called 'southern-half' at the State of Rio Grande do Sul, Brazil. The assessment has taken into account published scientific papers and geological maps, known use of geosites by local residents, as well as a digital terrain model (DTM), which has pointed out to some high altitude or steepness areas. We identified eight geosites and provided detailed description in terms of geodiversity, several potential points of tourism, on-going activities, and existing infrastructure. This assessment could be an incentive for the municipalities and especially the COREDE executive board as they could consider geotourism as an interesting opportunity for the social and economic sustainable development in the region. [ABSTRACT FROM AUTHOR]