Magnetic Zone Research Articles

Design of the $\mu$MAZE Platform and Microrobots for Independent Control and Micromanipulation Tasks

We present the μMAZE (μ(Micro) Magnetic Actuation Zone control Environment) platform for independent control of multiple magnetic microrobots for performing individual and collaborative micromanipulation tasks. We present a new local magnetic field generating coil system design, microrobot design, actuation scheme, and orientation control for actuating multiple magnetic microrobots independently. The new designs are validated and experiments showcasing their abilities are presented. The demonstrations include closed-loop independent and simultaneous control of four microrobots and a sample micromanipulation task involving two microrobots pushing micro-parts into a prescribed formation.

Otto Engine: Classical and Quantum Approach.

In this paper, we analyze the total work extracted and the efficiency of the magnetic Otto cycle in its classic and quantum versions. As a general result, we found that the work and efficiency of the classical engine is always greater than or equal to its quantum counterpart, independent of the working substance. In the classical case, this is due to the fact that the working substance is always in thermodynamic equilibrium at each point of the cycle, maximizing the energy extracted in the adiabatic paths. We apply this analysis to the case of a two-level system, finding that the work and efficiency in both the Otto’s quantum and classical cycles are identical, regardless of the working substance, and we obtain similar results for a multilevel system where a linear relationship between the spectrum of energies of the working substance and the external magnetic field is fulfilled. Finally, we show an example of a three-level system in which we compare two zones in the entropy diagram as a function of temperature and magnetic field to find which is the most efficient region when performing a thermodynamic cycle. This work provides a practical way to look for temperature and magnetic field zones in the entropy diagram that can maximize the power extracted from an Otto magnetic engine.

Application of Aeromagnetic Data to Assess the Structures and Solid Mineral Potentials in Part of North Central Nigeria

Assessment of the structures and solid minerals was carryout to investigate subsurface structural characteristics and mineralization potential zones within part of north-central Nigeria. The residual magnetic intensity data of the area was reduced to magnetic pole after which several source edge detection/interpretation with depth determination techniques including, analytic signal; tilt derivative; first and second vertical derivatives and Euler deconvolution were applied to the aeromagnetic data. From the analytic signal map, three magnetic zones were delineated. These are: low to relatively low magnetic zone (LM) with amplitude range from 0.003 to 0.009, moderate magnetic zone (MM) with amplitude 0.009 to 0.106 and those with amplitudes above 0.106 were products of later magmatic intrusions into host with fractures, faults and joints. Tilt derivative helped in delineating location and extent of edges of causative sources while Euler deconvolution helps in determination of boundary, depth and geometry of the structures. From first vertical derivative map, structures were found to have high lineament density around the central portion of the area and span toward the western end of the map were delineated. The lineaments mapped trending in the ENE-WSW followed by WNW-ESE with some NE-SW, NNE-SSW and NNW-SSE trends. The second vertical derivative (SVD) map also helped in delineating structures and possible mineralization zones that are pronounced within the study area, around high analytic signal zones. Delineated possible and favorable mineralization zones from second vertical derivative map correlate with portion of the study area with rocks showing high analytic signal amplitude suggesting the rocks to be of later magmatic intrusions where mineralization fluids solidify within the host rocks.

Geophysical exploration of Tural-Rajwadi group of hot springs, West Coast Geothermal Province, Maharashtra, India and its implications

Tural-Rajwadi group of hot springs (50−61.5 °C) is located in the southern part of the West Coast Geothermal Province (WCGP) of Maharashtra, India. The hot springs manifest in the basaltic terrain belonging to the Deccan Traps of Cretaceous-Paleocene age (∼65 Ma). To delineate the subsurface structures, a detailed geophysical exploration study has been carried out in the vicinity of the Tural-Rajwadi area for the first time deploying micro-gravity and micro-magnetic surveys in a grid of 1.25 × 4.0 km covering an area of 5 km2. The study shows prominent low gravity and low magnetic anomalies demarcating geothermal zones in the study area. Radial average power spectrum analyses of gravity and magnetic data infer seven interfaces of basalt lava flows in the subsurface. Evaluation of geophysical anomaly map reveals that the residual low gravity corroborates with a magnetic low anomaly zone and may indicate an association of a high-temperature gradient at shallow depth in the area. The study shows the presence of several NNW-SSE, NW-SE, NE-SW, and E-W lineaments, which predominantly control the manifestation of hot springs in the area. The distribution of faults, their boundaries, and depth extent have also been determined via derivative analyses, tilt derivative, and Euler’s deconvolution methods. Analyses of geophysical data using Werner deconvolution and radial average spectrum methods along two selected profiles indicate the presence of a vertical to sub-vertical conduits system extending to a deeper geothermal source in the study area. In addition, a 2D modeling study of gravity data along a 10 km profile estimates a shallow granite-gneiss basement in the depth range 770−800 m below ground level.

Targeting Geothermal Exploration Using Airborne Multi-geophysics, Kutcharo Caldera, Teshikaga Area

Multiple geophysical techniques have been applied to geothermal exploration within the Teshikaga area. The three-dimensional inversion of HeliFalcon® airborne gravity gradiometry (AGG) data has enabled a detailed interpretation of subsurface features. The vertically elongated high-density anomalies beneath lava domes located near Wakoto Peninsula and Mt. Atosanupuri are interpreted as subsurface intrusive bodies, while low-density anomalous feature to the depth represents the Kutcharo caldera structure, which was filled with large scale of low-density pyroclastic materials. Helitem® electromagnetic data acquired in combination with the AGG data revealed a widespread conductive anomaly west of Mt. Atosanupuri, which may represent the cap rocks to a geothermal reservoir. The distribution of a low magnetic intensity zone matches that of a low-resistivity zone, suggesting that magnetite degradation and demagnetization possibly occur, most likely caused by hydrothermal activities. Integrated interpretation of airborne gravity gradiometer, electromagnetic and magnetic data helps with identification of prospective areas and planning of a drilling program for the development of geothermal energy with greater precision.

An Integration of Magnetic, Gravity and Seismic Data in Evaluating the Algoa Basin in the Eastern Cape Province of South Africa for Stratigraphic and Structural Geodynamics

The Algoa Basin is a hydrocarbon potential basin which lies off the southern continental margin of South Africa, along the coastal region of Port Elizabeth area with both onshore and offshore components. Despite the continued consensus on the basin’s hydrocarbon potential, both its structural and stratigraphic geodynamics are still not well documented. In this study, gravity data constrained by borehole data was modelled to reveal onshore subsurface geology whereas the seismic sections were used for offshore. In addition, magnetic data was used to delineate magnetic zones and lineaments. The onshore magnetic results show the localised occurrence of large-scale geologic bodies, with high and positive anomalies forming bounding rims coincidental with the edges of the basin. The average depths to the top of the shallowest and deepest magnetic sources were estimated from the power spectrum to be approximately 0.4–0.6 km and 9.5 km, respectively. The onshore Bouguer gravity map is characterised by a gravity low zone over the basin’s sediment where it attains its lowest value over the depocentre. 2¾ D gravity modelling results along five profiles show that the basin comprises of two to three ‘“V” shaped’ sub-basins of shallow crustal depth with sediment thickness of up to 4.6 km. The models also revealed discontinuity in sediment units, confirming the diachronous nature of the Uitenhage Group. Analyses of offshore seven seismic sections show that the stratigraphic sequence consists of diachronous geological units, which are characterised by displacements, forming a series of minor and major faults. Complementary to onshore gravity models, seismic sections also shows relatively shallow vertical extension to the Paleozoic crustal basement between 1.3 and 5.3 km.

Combined geophysical investigations of the characteristics of a regional fault zone for groundwater development in a basement complex terrain of South-west Nigeria

This paper presents the results of an integrated electrical resistivity and magnetic survey of a strike slip fault in a basement complex terrain with poor well/borehole yield. It aims to characterize the fault zone and determine its geometry, width and depth extent and attitude that will enable an assessment of its prospectivity for groundwater development. The magnetic profiles imaged a fault block characterized by a low (negative) total field magnetic anomaly with a width extent ranging from 112 to 150 m, a depth extent in excess of 150 m and a near vertical disposition. The resistivity structures delineate low resistivity near vertical discontinuities within the high resistivity fresh basement host rock that correlate across the five traverses investigated. The north-western edge of the magnetic fault block and the resistivity anomalous zone correlates with the geo-referenced strike slip fault. The width of the low resistivity zone ranges from 75 to 125 m with depth extent in excess of 150 m. Four subsurface geologic/geoelectric layers were delineated. These include a relatively thin topsoil underlain by a clay/sandy clay weathered basement; a partly weathered/fractured basement column and a basal fresh basement with depth to rock head of 1.6–15.0 m. A zone with thick column (up to 117 m) of partly weathered/fractured basement correlates across the traverses and significantly with the anomalous magnetic and resistivity zones. The study concludes that the thicker region of partly weathered/fractured basement column within the fault zone which is likely to have enhanced permeability and storage capacities has potential for sustainable groundwater development. It also demonstrates the effectiveness of integrated 1D and 2D electrical resistivity imaging and magnetic profiling in structure (fault) identification, characterization, subsurface sequence delineation and groundwater potential assessment in a typical basement complex environment.

Distribution Features of the Nanhua‐Sinian Rifts and their Significance to Hydrocarbon Accumulation in the Tarim Basin

AbstractOn the basis of reprocessing 34 new two‐dimensional spliced long sections (20,191 km) in the Tarim Basin, the deep structure features of the Tarim Basin were analyzed through interpreting 30,451 km of two‐dimensional seismic data and compiling basic maps. Seismic interpretation and geological analysis conclude that the Nanhua‐Sinian strata are a set of rift‐depression depositional systems according to their tectonic and depositional features. The rift valley formed in the Nanhua Period, and the transformation became weaker during the late Sinian Period, which eventually turned into depression. From bottom to top, the deposited strata include mafic igneous, tillite, mudstone, and dolomite. Three major depocenters developed inside this basin during the rift stage and are distributed in the eastern Tarim Basin, the Awati area, and the southwestern Tarim Basin. Among them, the rift in the eastern Tarim Basin strikes in the near east‐west direction on the plane and coincides with the aeromagnetic anomaly belt. This represents a strong magnetic zone formed by upwelling basic volcanic rock along high, steep normal faults of the Nanhua Period. Controlled by the tectonic background, two types of sedimentary systems were developed in the rift stage and depression stage, showing two types of sequence features in the Sinian depositional stage. The Nanhua System appears as a wedge‐shaped formation, with its bottom in unconformable contact with the base. The rifting event has a strong influence on the current tectonic units in the Tarim Basin, and affects the distribution of source rock in the Yuertus Formation and reservoir beds in the Xiaoerbulake Formation in Lower Cambrian, as well as the gypseous cap rock in Middle Cambrian. The distribution features of the rifts have important and realistic significance for determining the direction of oil and gas exploration in the deep strata of the Tarim Basin. Comprehensive analysis suggests that the Tazhong region is the most favorable zone, and the Kalpin‐Bachu region is the optimal potential zone for exploring sub‐salt oil and gas in deep Cambrian strata.

A rock magnetic perspective of gas hydrate occurrences in a high-energy depositional system in the Krishna-Godavari basin, Bay of Bengal

We conducted a detailed rock magnetic study complemented by sedimentological and mineralogical methods on a 177.2-m-long sediment core of Hole NGHP-01-14A to constrain the influence of high-energy depositional environment on the magnetic mineral diagenesis and formation of gas hydrates in the Krishna-Godavari (K-G) basin, Bay of Bengal. Five sediment magnetic zones were identified based on the downcore variation in rock magnetic parameters. The magnetic mineralogies comprised of detrital titanomagnetite, diagenetically formed magnetic iron sulfides and their mixture. A distinct magnetically enhanced zone (Z-3) close to a bottom simulating reflector (BSR) is dominated by higher magnetite content, sediment bulk density, and grain size and probably represents several sand-rich sediment layers formed as a result of short-duration intense sedimentation events and got rapidly buried and provided conducive environment for the formation of gas hydrate deposits at the studied site. The concurrence of gas hydrates and high gas saturations within the sand-rich layers (Z-3) suggests that the high-energy depositional environment had a larger control over hydrate formation at Hole NGHP-01-14A. Two magnetic iron sulfide bearing sediment intervals in Z-1b and Z-1c below sulfate-methane transition zone (SMTZ) suggest that their formation is controlled by microbially mediated diagenetic reactions fuelled by presence of gas hydrates and probably represents the fossil gas hydrate zones. We propose that the rock magnetic variations in the studied sediment core at Hole NGHP-01-14A is controlled by both differential loading of detrital magnetic minerals as well as hydrate-induced late diagenetic magnetic iron sulfide formation.

Tectonic evolution of Kutch sedimentary basin, western India

Lithological variations, circular spectral anomalies, geological structures such as folds, faults, lineaments and shear zones of Kutch sedimentary basin were interpreted using IRS-LISS III satellite data. Aeromagnetic data was also interpreted qualitatively and quantitatively and a number of anomalous magnetic zones, faults, lineaments and domal structures were mapped. Magnetic basement depths and thickness of sediments were also computed. A number of alternate basement ridges/highs/uplifted blocks and depressions/lows/downthrown blocks were delineated. The information obtained from satellite remote sensing and aeromagnetic data were then integrated and the results were compared with published literature on gravity, magnetic (ground), magnetotelluric and seismic data, and also with field geology and well data. Structural controls in spatial domain (latitude, longitude and depth) were derived by establishing spatial relationship among different geological structures with reference to the geological time scale. Numerous horst and graben structures (ridges and sub-basins) as well as a number of master faults were delineated which serve as vital information with regard to hydrocarbon prospects and earthquake vulnerability, respectively. Based on the information obtained from this integrated study, a conceptual tectonometamorphic model along with sedimentation and igneous activity (ophiolitic and basaltic) has been constructed which has a significant bearing on the sequence of events that occurred during the deformational history of Kutch sedimentary basin resulting into the present day tectonic configuration.

Extended 1D defect induced magnetism in 2D MoS2 crystal

Exploring two dimensional (2D) magnetic materials is important for both fundamental research and practical applications in nanoscale spintronics. Although dispersive doping of atoms in 2D nonmagnetic transition-metal dichalcogenides (TMD) has been broadly studied in recent years, the regular linear substitution inside 2D nonmagnetic TMD is rarely explored. Herein, based on first-principles calculations, we report a series of hybrid magnetic structures formed by linear atomic doping in MoS2 monolayer. We demonstrate that F and Fe atoms linear-doped MoS2 are ferromagnetic semi-metals while Mn and Co atoms linear-doped MoS2 are ferromagnetic semiconductors in their ground states. Except for F dopant, the magnetic ground states of Mn, Fe, or Co atom linear-doped MoS2 are independent of the width of linear defect. The thermal and lattice dynamical stabilities of linear-doped MoS2 monolayer are confirmed with the molecular dynamics simulations and phonon spectra. A ferromagnetic semi-metal or semiconductor to half-metallic ferromagnet transition in doped MoS2 monolayer is revealed with applying strain. Further, atomically thin magnetic zones with different shapes can also be achieved by arranging the dopants. The induced magnetic properties render linear-doped MoS2 a promising material for spintronics in the nanoscale.

Geophysical responses and possible geothermal mechanism in the Gonghe Basin, China

In Qinghai Province of China, the Gonghe Basin is characterized as a potential hot dry rock (HDR) area due to the high heat flow rate and high-temperature records from several springs and drillings. However, the regional geothermal mechanism is still disputable and then essential to be discussed for the HDR exploration strategy, even for analysis in other areas. Geophysical methods are useful tools of analysing regional tectonic activities and geological structures, which are related to heat generation and conduction. In this paper, we mainly focus on the geophysical data within different scales. Firstly, we mapped the epicentral distribution along a profile covering Qinghai-Tibetan Plateau and the north part of India. This result shows that the Gonghe Basin was in a relatively stable area where less earthquake happened in deep zones (> 40 km). The geothermic mode should be thereby different from another geothermal field Yangbajain, which has a high frequency of earthquake events in deep zones (> 40 km). Secondly, we focus on the area of the Gonghe Basin and its surrounding area. By using the gravity and magnetic data, we estimated the Moho depth and Curie point depth through the Park-Oldenburg algorithm. The results indicate that the Gonghe Basin was at the gravity gradient zone without noticeable depth gap of Moho interface. The regional aeromagnetic data along with the Curie point depth was in a different trend. The high-value magnetic zone covers the major part of the Triassic igneous rock area. In this case, the heat from the deep zone (> 30 km) might not be the major contributor to the HDR forming here. Referred MT, seismic inversion results, we integrated all geophysical results. Based on this, a conceptual model in the Gonghe basin was then put forward. The low resistivity zones such as the magma capsules or melted granites in the upper-crust might be the significant heat resource for the HDR, although those from lower crust, mantle and the igneous rocks might make some contributions. The heat was conducted through the near-ground fractures and make the Gonghe Basin as a potential geothermal area, also validated by other geochemical evidence.

Static and dynamic magnetic properties of CoPt/NiFe bilayers: experiment and modelling

Static and dynamic magnetization behaviours in CoPt(10 nm)/NiFe(tNiFe) bilayers with variable NiFe thicknesses tNiFe = 0.5, 2.5, 4, 5.5 and 8.5 nm, were investigated. Hysteresis cycles were obtained from vibrating sample magnetometry measurements, while Brillouin light scattering technique was used to study the spin waves behaviour in these systems. The experimental results are analysed by means of a simple model taking into account the magnetic inhomogeneity of the CoPt layer composed of magnetic hard and soft zones distinguished by their anisotropy values. This model allows interpreting both the static and the dynamic magnetization measurements.

Intercalation-Driven Reversible Switching of 2D Magnetism

The recent discovery of magnetism in atomically thin chromium triiodide has initiated the quest for two-dimensional magnetic materials. In an alternate route, here we explore the reversible switching of magnetism in naturally antiferromagnetic monolayer ferrous dioxide. Our high-throughput spin-polarized density functional theory calculations reveal antiferromagnetic to ferrimagnetic switching through the manipulation of the local magnetic moments mediated by lithium and magnesium ion intercalation. Hardware-accelerator-assisted rigorous ab initio computations involving structure searching, molecular dynamics, adaptive kinetic Monte Carlo, and hybrid functionals ensure sustainability of such switching amid randomness, structural deformation, thermal vibrations, and environmental conditions. The proposed technique along with conventional lithography may be used to create selective magnetic zones in a macroscopically nonmagnetic material for spintronics and memory devices.

Confirmation of a Late Miocene Subchron C4n.2n‐1r From the Eastern Qaidam Basin in the NE Tibetan Plateau

AbstractRefining reversal ages and improving reversal patterns for the geomagnetic polarity timescale are a major task for the paleomagnetic community. The Late Miocene is a period during which the geomagnetic field experienced frequent perturbations and which dramatic environmental changes occurred. Thus, improved (sub)chron definition during this period will enable to provide additional age control points for better understanding age of paleoenvironmental changes. A prior study of the Late Miocene C4n.2n magnetic polarity zone at Ocean Drilling Program Site 1092 in the sub‐Antarctic South Atlantic Ocean has revealed the potential existence of a subchron (C4n.2n‐1r). However, this subchron has not been incorporated into the geomagnetic polarity timescale yet because its existence has not been confirmed. Moreover, the low sediment accumulation rate of 1.32 cm/kyr at Site 1092 hampers a confident estimation of the age and duration of this subchron. Here we present a high‐resolution paleomagnetic data set covering C4n.2n from the Huaitoutala section in the eastern Qaidam Basin, Northwest China, with an average sediment accumulation rate of ~22 cm/kyr. Nine reversed declination/inclination data points define a subchron near the top of C4n.2n, similar to age of reported C4n.2n‐1r at Ocean Drilling Program Site 1092. Cyclostratigraphy of the magnetic susceptibility record of the Huaitoutala section suggests that the age and duration of the C4n.2n‐1r are 7.7612–7.7554 Ma and 5.8 ± 2.1 kyr, respectively. Confirming the existence of C4n.2n‐1r from a northern hemisphere terrestrial site suggests that two geomagnetic reversals bounding this subchron have global imprints and that this subchron can potentially serve as marker for stratigraphic correlation.

Turonian–Coniacian Deposits of the Kamennyi Brod-1 Section (Southern Ulyanovsk-Saratov Trough)

The most stratigraphically representative section of Turonian–Coniacian in the right-bank part of the Volga region is found at the Kamennyi Brod-1 section (Olkhovka district of Volgograd oblast). The subdivision of carbonate rocks into zones is based on the complexes of benthic foraminifera and other accompanying groups of invertebrates. Regressive-transgressive tendencies in the evolution of the Turonian–Coniacian basin is also reflected in the quantitative ratio between benthic and planktonic foraminifera. The earlier unknown representatives of Turonian and Coniacian marine biota are revealed: silicon sponges, crinoids, starfish, brittle stars, and brachiopods. The magnetostratigraphic (magnetopolar and petromagnetic) characteristic of the section is obtained, and the magnetic zone of anomalous polarity is revealed against the background of normal polarity (N). It is supposed that anomalous directions of magnetization represent the stabilized vector sum of oppositely directed components, one of which (corresponding to reverse polarity) is the primary one.

Electronic, magnetic, and thermodynamic properties of the kagome layer compound FeSn

Single crystals of the single Kagome layer compound FeSn are investigated using x-ray and neutron scattering, magnetic susceptibility and magnetization, heat capacity, resistivity, Hall, Seebeck, thermal expansion, thermal conductivity measurements and density functional theory (DFT). FeSn is a planar antiferromagnet below TN = 365 K and exhibits ferromagnetic magnetic order within each Kagome layer. The in-plane magnetic susceptibility is sensitive to synthesis conditions. Resistivity, Hall and Seebeck results indicate multiple bands near the Fermi energy. The resistivity of FeSn is about 3 times lower for current along the stacking direction than in the plane, suggesting that transport and the bulk electronic structure of FeSn is not quasi 2D. FeSn is an excellent metal with Rho(300K)/Rho(2K) values about 100 in both directions. While the ordered state is antiferromagnetic, high temperature susceptibility measurements indicate a ferromagnetic Curie-Weiss temperature of 173 K, reflecting the strong in-plane ferromagnetic interactions. DFT calculations show a 3D electronic structure with the Dirac nodal lines along the K-H directions in the magnetic Brillouin zone about 0.3 eV below the Fermi energy, with the Dirac dispersions at the K points gapped by spin-orbit coupling except at the H point. The magnetism, however, is highly 2D with Jin-plane/Jout-of-plane = 10. The predicted spin-wave spectrum is presented.

Preliminary Geomagnetic Study of the Hot Spring Area in Rokan Hulu, Riau - Indonesia

Hot spring is commonly found in volcanic mountain areas. But in Rokan Hulu, a hot spring is found at a distance of about 15 km from the hills of Bukit Barisan. This study aims to conduct a physical study especially preliminary geomagnetic study of the Hot Spring in terms of the magnetic properties and topography of the area. As much as 26 points of the geomagnetic survey were conducted and used in this study. Some data corrections were applied to the data for making the reliable data interpretation. The results showed that there was a weakening of the magnetic field in the zone around Hot Spring itself and the low magnetic value was extended to the Southeast zone of Hot Spring. Topography shows the zone in this southeast has a height difference of fewer than 10 meters from the location of the Hot Spring. Allegedly this weak Magnetic zone is the source of heat from the Hot Spring.

Geophysical interpretation of the geology of the Stanthorpe region using aeromagnetic, gravity and radiometric data

This study provides an in-depth geophysical interpretation of the geology of the Stanthorpe region with a particular focus on hydrothermal alteration. The radiometric ternary map outlines the main lithological divisions in the region, which together with Th and Th/K ratio maps distinguish various granitic suites. Magnetic signatures delineate a non-magnetic zone within the low to moderately magnetic Stanthorpe Granite. The non-magnetic section, a north–northwest trending belt with a high density of faults and dykes is interpreted as a hydrothermal alteration zone that is narrower in the north, widens southwards, and is much more extensive at depth than is suggested by the surface alteration pattern. Modelling of gravity data reveals a massive low-density granitic intrusion extending to a depth of 10–15 km. The low-gravity section with modelled rock densities between 2450 and 2670 kg/m3 coincides with the low magnetic susceptibility zone in the magnetic model. High K, low Th and low Th/K also characterise the sections of the Stanthorpe Granite that have both low gravity and magnetic responses. Also conspicuous in the geophysical signatures within the non-magnetic zone is an ovoid feature of low magnetic response, high uranium content with moderate density, interpreted as a granitic pluton. Thus, decrease in magnetisation, changes in K concentration and corresponding low gravity with an associated high density of faults, fractures and dykes in the Stanthorpe region are the main features of the quartz–sericite–chlorite–muscovite hydrothermal alteration.

Reinterpretation of the suture zone between the Itabuna-Salvador-Curaçá and Jequié blocks, of the São Francisco Craton, Bahia, Brazil, using structural and geophysical data

The study area is located in the central portion of the São Francisco Craton (SFC), between two of the main blocks that compose this feature: the Jequié and the Itabuna-Salvador-Curaçá blocks. The main objective of this study was to reevaluate the transition zone between both blocks, employing airborne geophysical, geologic and structural data. The geophysical data are represented by gamma-ray spectrometry and magnetic surveys, which showed the structure of the lithotypes mapped and helped in the identification of their limits. The analysis of these images established five radiometric domains and six magnetic zones. The geophysical data interpreted along with mapping survey, with macroscopic description and structural data, allowed better identification of the suture zone between the referred blocks. The structural analysis identified four deformation phases, characteristic of a transpressional zone, uplifting the ISCB onto JB. The present study proposes the modification of the limits between these blocks to a more southern location and updates the regional geotectonic understanding of the central region of the state of Bahia.