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To further explore the geological structure and the Mesozoic–Paleozoic hydrocarbon prospects in the northern area of the South Yellow Sea (SYS), multiple geological and geophysical data were systematically gathered and compiled, including gravity and magnetic data, seismic surveys, drilling data, and previous research results. The characteristics and genesis of the gravity and magnetic anomalies are examined. This study employs residual gravity anomalies and multiple edge detection methods to identify fault lineament structures and assess the tectonic framework. Moreover, the study utilizes 2.5D gravity-seismic joint modellings and regression analysis to estimate the basement depth. Additionally, the study examines the basement characteristics and discusses the thickness of the Mesozoic–Paleozoic strata. Finally, the study further identifies prospects for hydrocarbons in the Mesozoic–Paleozoic. Our findings show that the faults are incredibly abundant and that the intensity of fault activity weakens gradually from NW to SE. Specifically, NE (NEE) trending faults are interlaced and cut off by NW (NWW), near-EW, and near-SN trending secondary faults, which form an en-echelon composite faults system with a dominant NE (NEE) orientation. Thick Mesozoic–Paleozoic strata are preserved, but we observe distinct variations in basement characteristics and the pre-Cenozoic structural deformation along the N-S direction. Therefore, the Northern Basin of SYS (NBSYS) and the Middle Uplift of SYS (MUSYS) are characterized by alternating sags and bulges in the S-N direction and in the E-W direction, respectively, forming a chessboard tectonic framework. Considering the oil and gas accumulation model, we identify three target hydrocarbon prospects in the NBSYS and two favorable hydrocarbon prospects in the MUSYS.

Residual terrain modelling (RTM) plays a key role for short-scale gravity modelling in physical geodesy, e.g. for interpolation of observed gravity and augmentation of global geopotential models (GGMs). However, approximation errors encountered in RTM computation schemes are little investigated. The goal of the present paper is to examine widely used classical RTM techniques in order to provide insights into RTM-specific approximation errors and the resulting RTM accuracy. This is achieved by introducing a new, independent RTM technique as baseline that relies on the combination of (1) a full-scale global numerical integration in the spatial domain and (2) ultra-high-degree spectral forward modelling. The global integration provides the full gravity signal of the complete (detailed) topography, and the spectral modelling that of the RTM reference topography. As a main benefit, the RTM baseline technique inherently solves the “non-harmonicity problem” encountered in classical RTM techniques for points inside the reference topography. The new technique is utilized in a closed-loop type testing regime for in-depth examination of four variants of classical RTM techniques used in the literature which are all affected by one or two types of RTM-specific approximation errors. These are errors due to the (1) harmonic correction (HC) needed for points located inside the reference topography, (2) mass simplification, (3) vertical computation point inconsistency, and (4) neglect of terrain correction (TC) of the reference topography. For the Himalaya Mountains and the European Alps, and a degree-2160 reference topography, RTM approximation errors are quantified. As key finding, approximation errors associated with the standard HC ( 4 π G ρ H P RTM ) may reach amplitudes of ~ 10 mGal for points located deep inside the reference topography. We further show that the popular RTM approximation ( 2 π G ρ H P RTM - TC ) suffers from severe errors that may reach ~ 90 mGal amplitudes in rugged terrain. As a general conclusion, the RTM baseline technique allows inspecting present and future RTM techniques down to the sub-mGal level, thus improving our understanding of technique characteristics and errors. We expect the insights to be useful for future RTM applications, e.g. in geoid modelling using remove–compute–restore techniques, and in the development of new GGMs or high-resolution augmentations thereof.

During the last years, many new results related to the thickness of the sedimentary fill and other geophysical and geological constrains on the structure of the Turčianska Kotlina Basin have been obtained. It allowed us to calculate the first, original stripped gravity map in this basin. To obtain this map the 3D gravity effect of the basin sedimentary fill had to be calculated. The gravity effect of the sediments was determined for two different density conditions. Firstly, the average density of the sediments was constant (2.45 g cm−3). Secondly, we supposed that the density of sediments varies exponentially from 2.00 g cm−3 on the surface up to 2.67 g cm−3 on the pre-Tertiary basement. On the maps of the calculated gravity effects it can be observed that the maximum amplitudes reach about -12 mGal. The gravity effect is larger in the case when the densities of the sedimentary fill vary exponentially. After subtraction of the gravity effects from the map of complete Bouguer gravity map, the resultant stripped gravity maps were defined. The detailed analysis of these maps indicates that the northern part of the pre-Tertiary basement of the basin could be built mostly by the Mesozoic rocks, which belong to the Hronic and Fatric units. The structure of the basement in the southern part of the basin seems to be more complicated. This feature probably reflects a presence of Neogene volcanites in the basin basement belonging to the Kremnické vrchy Mts. The picture of the gravity field in the stripped gravity map predicts that the Paleogene sediments probably do not build the sedimentary fill in the southern part of the basin. Finally, taking into account the differences in the size of the gravity gradients along the basin margins it could be suggested that the dipping of the Veľká Fatra Mts. beneath the Turčianska Kotlina basin is gentle in comparison with the Lučanská Malá Fatra.

Although cratons have long been recognized as an important part of continental tectonic processes, we still have much to learn about their structural features and their relation to the genesis of basins, sedimentary thickness distributions, fold and thrust belts and surface processes. Contributing to a better knowledge of the crustal state and configuration of the southernmost part of the Río de la Plata Craton, could shed light on the still controversial tectonic processes, which were responsible for the deformation of the southwestern margin of Gondwana during the Late Paleozoic. In particular, the deformation and uplift of the Sierras Australes, which are part of the Claromecó Basin (Buenos Aires, Argentina), would be closely related to the crustal structure of the southern limit of the Río de la Plata Craton. Therefore, it is of crucial importance to investigate the possible existence of crustal heterogeneities underneath the Claromecó Basin, the Sierras Australes and the Colorado Basin, which can be related to structural features and weakness zones that could have played a major role in the tectonic evolution of the study area. For this purpose, we developed a 3D lithospheric-scale density model integrating various data, such as geological information, global gravity models, well data (thicknesses and lithologies), seismic tomography data (Moho depth), and pre-existing 3D density models of the Colorado Basin. Our model includes layers of sediments, crystalline crust and lithospheric mantle and therefore predicts the thickness variation of the upper and lower crust in the study area and of the main sedimentary sequences infilling the basins. Moreover, by analysing the model results, we propose a tentative location of the southern limit of the Río de la Plata Craton and its possible tectonic relationship with transfer zones identified in the Atlantic platform southwards. Our results suggest that the southern boundary of the craton is located along the northernmost limit of the Colorado Basin, which is in contrast with the boundary proposed in previous works. Therefore, we propose that the Colorado Basin rifting process could have occurred along this weakness domain.

Space missions to small bodies like asteroids, comets, and moons rely on physics-based simulations to test guidance and control systems. However, accurately modeling their gravitational fields is challenging due to their highly irregular shapes and limited knowledge of their internal structures, complicating orbit planning and landing maneuvers. This study presents a new approach to model realistic density distributions based on Voxel-shaped mass concentrations. We apply body-specific constraints to three-dimensional Perlin noise, supplemented with normalization and segmentation techniques. Additionally, various structural elements can be incorporated into the density distribution. These include centralized and decentralized shells of different thicknesses and densities, as well as anomalies of varying sizes and shapes. Normalization techniques ensure the body’s total mass conservation. We validate our method by calculating the gravitation of a cube and sphere with constant density and comparing it with its analytical solution. We further compare our method with other mascon approaches and the polyhedral method at different Voxel resolutions and conduct additional performance evaluations of our method using test scenarios with focus on geophysical parameters such as the moments of inertia tensor and the gravity field’s spherical harmonics expansion. Our results demonstrate the method’s ability to account for realistic density distributions and to accurately compute the corresponding gravitational fields and geophysical properties.

The southern Central Andes (SCA) (between 27° S and 40° S) is bordered to the west by the convergent margin between the continental South American Plate and the oceanic Nazca Plate. The subduction angle along this margin is variable, as is the deformation of the upper plate. Between 33° S and 35° S, the subduction angle of the Nazca plate increases from sub-horizontal (< 5°) in the north to relatively steep (~ 30°) in the south. The SCA contain inherited lithological and structural heterogeneities within the crust that have been reactivated and overprinted since the onset of subduction and associated Cenozoic deformation within the Andean orogen. The distribution of the deformation within the SCA has often been attributed to the variations in the subduction angle and the reactivation of these inherited heterogeneities. However, the possible influence that the thickness and composition of the continental crust have had on both short-term and long-term deformation of the SCA is yet to be thoroughly investigated. For our investigations, we have derived density distributions and thicknesses for various layers that make up the lithosphere and evaluated their relationships with tectonic events that occurred over the history of the Andean orogeny and, in particular, investigated the short- and long-term nature of the present-day deformation processes. We established a 3D model of lithosphere beneath the orogen and its foreland (29° S–39° S) that is consistent with currently available geological and geophysical data, including the gravity data. The modelled crustal configuration and density distribution reveal spatial relationships with different tectonic domains: the crystalline crust in the orogen (the magmatic arc and the main orogenic wedge) is thicker (~ 55 km) and less dense (~ 2900 kg/m3) than in the forearc (~ 35 km, ~ 2975 kg/m3) and foreland (~ 30 km, ~ 3000 kg/m3). Crustal thickening in the orogen probably occurred as a result of stacking of low-density domains, while density and thickness variations beneath the forearc and foreland most likely reflect differences in the tectonic evolution of each area following crustal accretion. No clear spatial relationship exists between the density distribution within the lithosphere and previously proposed boundaries of crustal terranes accreted during the early Paleozoic. Areas with ongoing deformation show a spatial correlation with those areas that have the highest topographic gradients and where there are abrupt changes in the average crustal-density contrast. This suggests that the short-term deformation within the interior of the Andean orogen and its foreland is fundamentally influenced by the crustal composition and the relative thickness of different crustal layers. A thicker, denser, and potentially stronger lithosphere beneath the northern part of the SCA foreland is interpreted to have favoured a strong coupling between the Nazca and South American plates, facilitating the development of a sub-horizontal slab.

The present-day crustal structure of tectono-magmatic regions is the product of dynamic interactions of crust and mantle materials. The Narmada–Tapti region is a mosaic of tectono-magmatic signatures and is characterized by active seismicity, deep-seated faults, shear zones, and high heat flow, suggesting it to be a zone of crustal weakness. The availability of ample seismic and magnetotelluric datasets and inherent complexity drew our attention to image the crustal structure in the third dimension using high-resolution gravity data. The derived 3D crustal density model shows that the Deccan trap extends from 200–1700 m partly below the 90–150 m thick Quaternary sediment exposed in some pockets. The sub-trappean Mesozoic sediment is present at a depth of 250–2400 m followed by the basement. Our 3D model further shows that the high gravity values in residual anomalies are due to high-density magmatic intrusions between 1.5 and 9 km depth. The gravity high in regional anomaly is modelled with a broad dome-shaped high-density (3.02 g/cm 3 ) underplated layer between 14 and 38 km depth. The spatial correlation of delineated high-density lower crustal body with the high-velocity and high conductivity zones mapped by earlier workers in this region indicates the possible presence of mantle magma intrusion in the realm of Deccan volcanism. Analysis of isostatic residual anomaly indicates that the region beneath Narmada–Tapti is not in local isostatic equilibrium. Analysis of the isostatic residual anomaly, root depth, and crustal thickness from the 3D model further ascertains the modification of the crust due to the interaction of mantle plume material. The gravity effect of residual geoid up to 50 km corroborates the high-density magmatic material distribution at two different places, i.e., one at Navsari near the west coast and the other is Junapani near Khandwa. The region has signatures of upliftment and together with the crustal-scale basic magmatic intrusion, satisfies both high gravity anomalies and positive residual geoid undulation. The residual geoid undulations are bounded by major tectonic faults and together with the magmatic underplate at the crustal base indicate that these faults were activated during the Deccan magmatism. Research Highlights Narmada-Tapti region has a weak crustal architecture with crustal and sub-crustal magmatic intrusions, dyke swarms, atypical geophysical signatures, and crustal upliftment. 2½D crustal density modelling along available seismic sections using high-resolution gravity data in Narmada-Tapti region. Three-dimensional crustal-scale density structure with multistage magmatic intrusion in the Narmada-Tapti region, central India. Positive Bouguer and isostatic anomalies and geoid undulation over the Narmada-Tapti region provide extra arguments for densification of the crust through multistage magmatic intrusions caused by the Deccan magmatism. About 250–2400 m thick Mesozoic sediments delineated at a depth of about 500–3000 m illustrates the potential for hydrocarbon exploration in the Narmada-Tapti region.

The Ambaji–Deri region is located in the northeastern part of the Gujarat state of India and is well-known for hosting lead–zinc–copper minerals deposits. Recently, gravity and magnetic data are collected in the region with the objective of geological and structural mapping of the area. This data is further processed using upward continuation, derivative analysis, and 2.5-dimensional gravity modelling to understand the subsurface geometry for mineral exploration. The upward continued regional gravity anomaly reveals high value in SW part of the region. The residual gravity and magnetic anomaly show the NE–SW trend, which is sympathetic with the general trend of Delhi supergroup. The high values of the residual Bouguer and the magnetic anomaly at the junction of the Jaisalmer–Barwani and the Chambal–Jamnagar lineaments are inferred as possible potential sites for sulphide mineralisation. The horizontal gradient of the tilt derivative (HGTD) of both the gravity and the magnetic anomalies reveals NE–SW trending lineaments. Based on the results of HGTD, several new structural features have been identified and a refined lineament map of the study area is proposed. The gravity modelling using residual Bouguer anomaly could delineate a high-density intrusive body in the upper crustal level. The result of the gravity model also confirms that the middle crust is uplifted by 1–3 km in the eastern part of the study area. In this study, three prospective zones for base metal mineralisation have been identified.

Anthropogenic activities can greatly affect the ecological environment. As an ecological protection area, it is necessary to scientifically evaluate the landscape ecological risk (LER) in the Dongjiangyuan region to provide scientific guidance for regional sustainable development. In this study, the LER was calculated, and the spatial and temporal characteristics of the LER from 1985 to 2020 were analysed using geospatial techniques. The results show that the proportion of low-risk and extremely low-risk areas increased from 87.65% to 94.26% during the 1985-2020 period. The extremely high-risk and high-risk areas had a decreasing trend, and the extremely high-risk areas were concentrated in areas with impervious surfaces and croplands. The rate of risk was negative, especially in south-eastern Xunwu County, southern Dingnan County and central Anyuan County, indicating that the ecological risk has been greatly improved. The LER centre gradually migrated to the geometric centre of the study area. However, the gravity centre of extremely high risk and high risk remained in Xunwu County. The spatial agglomeration of LER changed significantly, and the overall difference between cold areas and hot areas decreased. The hot spot areas in the Dongjiangyuan region are key areas for ecological governance in the future.

The spherical radial basis function (SRBF) approach, widely used in gravity modeling, is theoretically surveyed from a viewpoint of random field theory. Let the gravity potential be a random field which is represented as an integral functional of another random field, namely an isotropic Gaussian random field (IGRF) on a sphere inside the Bjerhammar sphere with the SRBF as the integral kernel. When the integration is approximated by a discrete sum within a local region, one gets the widely applicable SRBF model. With this theoretical study, the following two findings are made. First, the IGRF implies a Gaussian prior on the spherical harmonic coefficients (SHCs) of the gravity potential; for this prior the SHCs are independent with each other and their variances are degree-only dependent. This should be reminiscent of two well-known priors, namely the power-law Kaula’s rule and the asymptotic power-law Tscherning-Rapp model. Second, the IGRF-SRBF representation is non-unique. Benefiting from this redundant representation, one can employ a simple IGRF, e.g., the simplest white field, and then design the SRBF accordingly to represent a potential with desired prior statistical properties. This can simplify the corresponding SRBF modeling significantly; to be more specific, the regularization matrix in parameter estimation of the SRBF modeling can be chosen to be a diagonal matrix, or even the naïve identity matrix.