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The 3‐D structure of continental metamorphic core complexes (MCCs) and their coevolution along with the associated extensional detachments are still not well understood. In this study, analysis of a newly acquired high‐resolution 3‐D seismic reflection volume reveals for the first time a well‐imaged MCC in the proximal northern South China Sea (SCS) rifted margin, the Kaiping MCC (KP MCC). These data provide a 3‐D view of the KP MCC and the associated KP detachment fault. The KP MCC is characterized by ascend of ductile midcrustal materials, and it is partially exhumed in the KP9 High. The KP detachment fault displays a domed low‐angle geometry, and is characterized by pronounced NS‐plunging corrugations, among which two megacorrugations of tens of kilometers are revealed. Evidence show that the KP MCC developed according to the classical rolling‐hinge model. A group of secondary normal faults and fractures, which are parallel to the axis of the KP MCC and offset the KP detachment surface at the crest of the MCC, developed in response to inelastic bending during progressive warping of the footwall. The migration of the domal seismic reflection layers provides a visual evidence for the kinematic process of the rolling‐hinge activity, during which the brittle‐ductile transition and the rolling hinge gradually migrate as the detachment fault slips. The origin of the KP MCC in the northern SCS margin is suggested to have been favored by the existence of a pre‐existing midcrustal ductile layer and basement structures within the upper brittle crust. Plain Language Summary: A metamorphic core complex (MCC) is an exposure of deep crust associated with extensional processes. Current understanding on MCCs is mainly derived from outcrop and geomorphic studies that only allow their exhumed part to be observed. A newly acquired 3‐D seismic reflection volume reveals a well‐imaged MCC, the Kaiping MCC (KP MCC), in the proximal northern South China Sea (SCS) rifted margin, permitting, for the first time, a detailed 3‐D examination of the MCC structure and its associated detachment fault. In this study, we present the 3‐D structure of the KP MCC, the geometry and kinematics of the associated KP detachment fault, and then we discuss the development and origin of the KP MCC. We propose that the KP MCC developed according to the rolling‐hinge model, with our data providing a visual evidence for the kinematic processes during which the brittle‐ductile transition and the rolling hinge gradually migrate as the detachment fault slips. We suggest that the origin of the KP MCC is favored by the existence of a pre‐existing midcrustal ductile layer and basement structures within the upper crust. Our study not only have implication for the SCS rifting but also advance understanding on the development and origin of MCCs. Key Points: A first imaged metamorphic core complex (MCC) in the proximal northern South China Sea rifted margin and its 3‐D structure is describedVisual evidence for the gradual migration of the brittle‐ductile transition and rolling hinge during the rolling‐hinge evolution of a MCCThe origin of the MCC was favored by a pre‐existing midcrustal ductile layer and basement structures within the upper crust [ABSTRACT FROM AUTHOR]

Studies of mountain belts worldwide show that along-strike changes are common in their foreland fold-and-thrust belts. These are typically caused by processes related to fault reactivation and/or fault focusing along changes in sedimentary sequences. The study of active orogens, like Taiwan, can also provide insights into how these processes influence transient features such as seismicity and topography. In this paper, we trace regional-scale features from the Eurasian continental margin in the Taiwan Strait into the south central Taiwan fold-and-thrust belt. We then present newly mapped surface geology, P wave velocity maps and sections, seismicity, and topography data to test the hypothesis of whether or not these regional-scale features of the margin are contributing to along-strike changes in structural style, and the distribution of seismicity and topography in this part of the Taiwan fold-and-thrust belt. These data show that the most important along-strike change takes place at the eastward prolongation of the upper part of the margin necking zone, where there is a causal link between fault reactivation, involvement of basement in the thrusting, concentration of seismicity, and the formation of high topography. On the area correlated with the necking zone, the strike-slip reactivation of east northeast striking extensional faults is causing sigmoidal offset of structures and topography along two main zones. Here basement is not involved in the thrusting; there is weak focusing of seismicity and localized development of topography. We also show that there are important differences in structure, seismicity, and topography between the margin shelf and its necking zone. [ABSTRACT FROM AUTHOR]

The 1:5000 scale Geological Map of the Fontane talc mineralization (FTM) aims to give new information about the origin and geological structure of an important talc mineralization occurring in the axial sector of the Italian Western Alps. The FTM is hosted within a pre-Carboniferous polymetamorphic complex which was deformed and metamorphosed during both Variscan and Alpine orogenesis, and is part of the Dora-Maira continental crust. Field mapping and underground investigations highlight that the talc bodies (i) never crop out but occur at depth along a well-defined lithostratigraphic association between micaschist, marble and gneiss and (ii) were deformed during different Alpine-related deformation phases (i.e. D1, D2and D3syn-metamorphic phases and post-metamorphic extensional faulting). The here defined lithostratigraphic and structural characterization of talc bodies, is an input for further research into the geodynamic context of where talc forms and for new mineral exploration outside the mapped area. [ABSTRACT FROM AUTHOR]

The Alishan area of Taiwan spans the transition from the platform with full thickness of the Eurasian continental margin in the north to the thinning crust of its slope in the south. This part of the foreland thrust and fold belt includes important along-strike changes in structure, stratigraphy, and seismic velocities. In this paper we present the results of new geological mapping from which we build geological cross sections both across and along the regional structural trend. Fault contour, stratigraphic cutoff, and branch line maps provide 3-D consistency between the cross sections. Minimum shortening is estimated to be ~15 km with displacement overall to the northwest. A P wave velocity model helps constrain the structure at depth by providing insight into the possible rock units that are present there. P wave velocities of ≥ 5.2 km/s point toward the presence of basement rocks in the shallow subsurface throughout much of the southeastern part of the area, forming a basement culmination. The changes in strike of thrusts and fold axial traces, the changing elevation of thrusts and stratigraphic contacts, and the growing importance of Middle Miocene sediments that take place from north to south are interpreted to be associated with a roughly northeast striking lateral structure coincident with the northern flank of this basement culmination. These transverse structures appear to be associated with the inversion of Eocene- and Miocene-age extensional faults along what was the shelf-slope transition in the Early Oligocene, uplifting the margin sediments and their higher P wave velocity basement during Pliocene-Pleistocene thrusting. [ABSTRACT FROM AUTHOR]

Defining the origin of ground deformation, which can be a very challenging task, may be approached through several investigative techniques. Ground deformation can originate in response to both natural (e.g., tectonics) and anthropic (e.g., groundwater pumping) contributions. These may either act simultaneously or be somewhat correlated in space and time. For example, the location of structurally controlled basins may be the locus of enhanced human-induced subsidence. In this paper, we investigate the natural and anthropic contributions to ground deformation in the urbanized area of the inner Sarno plain, in the Southern Apennines. We used a multidisciplinary approach based on the collection and analysis of a combination of geomorphological, stratigraphical, structural, hydrogeological, GPS, and DInSAR datasets. Geomorphological, stratigraphical, and structural data suggested the occurrence of a graben-like depocenter, the Sarno basin, bounded by faults with evidence of activity in the last 39 ka. Geodetic data indicated that the Sarno basin also experienced ground deformation (mostly subsidence) in the last 30 years, with a possible anthropogenic contribution due to groundwater pumping. Hydrogeological data suggested that a significant portion of the subsidence detected by geodetic data can be ascribed to groundwater pumping from the alluvial plain aquifer, rather than to a re-activation of faults in the last 30 years. Our interpretation suggested that a positive feedback exists between fault activity and the location of area affected by human-induced subsidence. In fact, fault activity caused the accumulation of poorly consolidated deposits within the Sarno basin, which enhanced groundwater-induced subsidence. The multidisciplinary approach used here was proven to be successful within the study area and could therefore be an effective tool for investigating ground deformation in other urbanized areas worldwide. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the structure of the Cenozoic rift basin in the proximal domain of the northern South China Sea (SCS) margin, with an emphasis on the influence exerted by pre‐existing basement faults on rift development. Results of our work indicate that the overall rift architecture of the proximal domain of the northern SCS margin is associated with extensional faults arranged in two main structural trends, WNW‐ to EW‐trending and ENE‐trending. Structural evidence presented in this paper suggests that extensional faults of the two main structural trends mainly reactivated two pre‐existing basement fault systems mapped in previous works, a WNW‐ to EW‐striking thrust fault system (PFS1) and an ENE‐striking thrust fault system (PFS2). During the first rifting phase, both pre‐existing fault systems were reactivated; however, strains and depocenters were mainly localized on the ENE‐striking normal fault system that reactivated the PFS2. On the contrary, in the second rifting phase, extension was mainly accommodated by WNW‐ to EW‐striking normal faults that reactivated the PFS1, while most of the earlier ENE‐striking normal faults became inactive or less active. These different degrees of reactivation of the two pre‐existing fault systems during the two rifting phases suggest a clockwise rotation of the regional extension direction from NNW‐SSE in the Syn‐rift stage 1 to N‐S in the Syn‐rift stage 2. This study implies that apart from Cenozoic tectonic processes, pre‐existing structures have also played a key role during rifting evolution across the SCS margin. Key Points: Two main structural trends in the proximal domain of the northern SCS rifted marginThe rift structure and evolution was significantly influenced by reactivation of two pre‐existing basement fault systemsChange of the regional extension direction from Syn‐rift 1 to Syn‐rift 2 indicated by reactivation pattern of pre‐existing fault systems [ABSTRACT FROM AUTHOR]