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Continental break‐up can be oftentimes associated with intracontinental wrenching that can lead to the generation of transform margins and transform marginal plateaus. The wrenching phase can be accompanied by complicated processes, which result in heterogeneous structural and crustal architectures. This makes understanding the evolution of such tectonic settings challenging. The Falkland Plateau is an example of a transform marginal plateau where regional wrenching accompanied the incipient stages of Gondwanan continental break‐up to result in a mosaic of crustal types underlying its largest basin: the Falkland Plateau Basin (FPB). The uncertainties in crustal boundaries have led to several models for the evolution of the plateau, which hinder the development of a reliable plate reconstruction of Southern Gondwana. We integrate seismic reflection, gravity and magnetic data to propose an updated crustal architecture of the FPB. The results show that extended continental crust underlies the basin in the west and north. The eastern and central parts consist of a juxtaposition of intruded and underplated continental crust which transitions southwards to a thick oceanic domain. The basin is crosscut by three main NE–SW trending shear zones which facilitated the development of the contrasting crustal and structural domains interpreted across the plateau. This integrated reassessment of the FPB provides new insights into the tectonic evolution of the plateau, the deformation associated with wrenching and transform margin formation and our understanding of the tectono‐stratigraphic evolution of such areas. [ABSTRACT FROM AUTHOR]

The stretched structure and heterogeneity of the crust of the Nansha Block, the southern continental margin of the South China Sea (SCS), are not well understood. We used published ocean bottom seismic (OBS)/multichannel reflection seismic (MCS) profiles across the Nansha Block to establish five two-dimensional crustal structure models. Using gravity modelling with magnetic anomaly inversion, we obtained the distribution of density and local magnetic susceptibility of the crust. The models show that the distribution of density and thickness of the upper crust in the Nansha Block is uneven, and the thick upper crust is prevalent in the regions close to the continent-ocean transition (COT) showing different characteristics. The interpreted Mesozoic granite blocks and Precambrian rigid basement reflects the heterogeneity in the material composition of the SCS continental margin. Based on the thinning styles of different crustal layers, we suggest that the Nansha Block has a three-layer thinning pattern. The uppermost pre-rift layer was deformed via brittle fractures, the upper crust was sheared by discrete shear zones, and the lower crust experienced ductile deformation. The inherited pre-rift thermal regime, mechanical state, and material composition of the SCS continental margin affected the extensional structure of the crust. [ABSTRACT FROM AUTHOR]

We present a joint interpretation of the aeromagnetic and gravity anomaly datasets of the Precambrian Eastern Ghats Mobile Belt, eastern India, to delineate the detailed crustal architecture, identify faults and shear zones, as well as boundaries of different terranes throughout this belt. We use geological constrained analysis of the distinct aeromagnetic anomaly signatures to re-interpret the extent of the Jeypore, Krishna, Eastern Ghats, and Rengali Provinces. Forward modelling of paired gravity anomalies and an increase in magnetic response along the craton-mobile belt boundary reveal that it is dominated by high-density and highly magnetic granulite facies rocks that overthrust the low-density and low magnetic older cratonic gneissic rocks along the deep crustal faults, suggesting the Eastern Ghats Mobile Belt terranes are allochthonous in nature. Two high magnetic anomaly belts in the Krishna and Eastern Ghats Provinces define a terrane-scale fold (orocline). The younger normal faults of Godavari Basin overprint the charnockitic belt in the southern part of the Eastern Ghats Province, suggesting that these high magnetic belts pre-date the Pan-African Orogeny. The boundary between the Eastern Ghats Province and Krishna Province is identified by the change in anomalies in magnetic and gravity maps. The Sileru Shear Zone and Kerajung Shear Zone separates the Eastern Ghats Province-Jeypore Province and Eastern Ghats Province-Rengali Province respectively, are characterized by a sharp change in magnetic anomalies. The intra-province Nagavali-Vamsadhara Shear Zone and Mahanadi Shear Zone are characterized by subdued magnetic anomalies. Inversion of the regional gravity anomalies revealed that the Moho is slightly shallower (~5 km) beneath the Eastern Ghats Mobile Belt compared to the neighbouring Cratons. • The subsurface extent of various terranes of the Eastern Ghats Mobile Belt is delineated by structural geophysical analysis. • Crustal architecture of the Eastern Ghats Mobile Belt is redefined from joint interpretation aeromagnetic and gravity data. • The present study reveals that the Eastern Ghats Mobile Belt is an allochthonous. [ABSTRACT FROM AUTHOR]

Deep seismic reflection data across the Archaean Eastern Goldfields Province, northeastern Yilgarn Craton, Western Australia, have provided information on its crustal architecture and on several of its highly mineralised belts. The seismic reflection data allow interpretation of several prominent crustal scale features, including an eastward thickening of the crust, subdivision of the crust into three broad layers, the presence of a prominent east dip to the majority of the reflections and the interpretation of three east-dipping crustal-penetrating shear zones. These east-dipping shear zones are major structures that subdivide the region into four terranes. Major orogenic gold deposits in the Eastern Goldfields Province are spatially associated with these major structures. The Laverton Tectonic Zone, for example, is a highly mineralised corridor that contains several world-class gold deposits plus many smaller deposits. Other non crustal-penetrating structures within the area do not appear to be as well endowed metallogenically as the Laverton structure. The seismic reflection data have also imaged a series of low-angle shear zones within and beneath the granite–greenstone terranes. Where the low-angle shear zones intersect the major crustal-penetrating structures, a wedge shaped geometry is formed. This geometry forms a suitable fluid focusing wedge in which upward to subhorizontal moving fluids are focused and then distributed into the nearby complexly deformed greenstones. [Copyright &y& Elsevier]

• Upright folds overlying a fault zone in the Chicobi belt formed at 2696–2681 Ma. • Integrated data show this fault zone dips northward shallowly at 3–7 km depths. • Crustal architecture and chronology suggest an allochthonous model at ca. 2.7 Ga. Our understanding of crustal architecture and tectonic evolution has advanced due to integrated geological and geophysical research on Precambrian cratons. However, it is still a heated debate whether Archean crust structure developed by an allochthonous model similar to modern plate tectonics or autochthonous model emphasizing in-situ evolution of supracrustal belts. The < ca. 2696 Ma Chicobi belt is a sedimentary basin in the central Abitibi Subprovince of the Superior Province, and as such provides a unique opportunity to contribute to this debate. It comprises both Porcupine-type turbidite and Timiskaming-type polymictic conglomerate and cross-bedded sandstone, and unconformably overlies ca. 2728–2711 Ma metavolcanic rocks, including the Amos Group to the south. The metasedimentary rocks were deposited after an early (D 1 > ca. 2696 Ma) deformation event, which is expressed by internally foliated clasts in conglomerate. The Chicobi belt was regionally folded and cut by shear zones during a second (D 2) deformation event, and was re-folded by Z-shaped folds during a third (D 3) dextral shearing event. The D 2 event is constrained between ca. 2696 Ma, the pre-existing age of detrital zircon in the Scapa Group along strike of the Chicobi belt, and ca. 2681 Ma, the new age of the cross-cutting syenitic Gémini-Saint-Éloi Pluton. New high-resolution seismic reflection and magnetotelluric surveys were conducted along the same transect across the Chicobi belt. The seismic reflection survey imaged subhorizontal to shallowly north-dipping reflective bands at depths of 3–7 km. Regional-scale inversion of new and pre-existing gravity data indicates that these reflective bands are linked to the Beauchamp Fault south of the Amos Group. Magnetotelluric inversion model shows high resistivity (>1000 Ω·m) zones under metasedimentary rocks, as well as a synform defined by low resistivity (10–100 Ω·m) zones, which aligns with folded metavolcanic rocks south of the Chicobi belt. Integration of the geophysical data with surface mapping suggests that the upper-middle crustal architecture of the Chicobi belt is dominated by D 2 upright folds overlying a fault zone. We suggest that deformation of the Chicobi belt is dominated by thrusting and folding, a deformation style compatible with allochthonous growth of the Abitibi Subprovince. [ABSTRACT FROM AUTHOR]