Tiago M. Alves

Land‐detached submarine canyons are typically developed on broad continental shelves, where direct fluvial sediment supply is absent. This often leads to their interpretation as inactive sediment conduits, contrasting with recent monitoring studies revealing the presence of turbidity currents in these canyons. The northeastern South China Sea is characterised by a wide shelf with limited sediment input from large rivers, though it experiences frequent tropical storms. This unique setting provides an ideal opportunity to investigate the effects of storm‐enhanced sediment transport on submarine canyon activity. This work quantifies the contribution of storms to sediment transport from the continental shelf to submarine canyons using numerical calculations based on surface sediment grain size, bathymetric data and regional wave field conditions obtained from the ERA5 model. Using an extensive dataset from the South China Sea, the results demonstrate that under storm‐wave conditions, the combination of extreme wave heights and shallow water depths increases the likelihood of shelf‐sediment transport during storms, a process that affects up to 64% of the continental shelf. Our results reveal a dual mechanism sustaining canyon activity: First, storm waves remobilise shelf sediments that are subsequently advected toward canyon heads by currents, preconditioning the slopes through gradual accumulation. Second, during the most energetic events, local remobilisation near the shelf edge generates suspended sediment concentrations exceeding the ~40 g l ⁻¹ threshold, directly triggering sediment gravity flows on steep canyon slopes. The analysis presented here provides valuable insights into the role of storms in facilitating sediment transport from the shelf to canyon heads, and elucidates how storms influence the activity of land‐detached submarine canyons.

Quantifying rift obliquity and coaxiality from seismic data remains intrinsically difficult in polyphase rifted margins, where fault populations of different ages, hierarchical orders and spatial scales are commonly analysed together. This practice can blur kinematically meaningful signals and leads to interpretations that are hard to compare across domains and through time. This study aims to (1) present a seismic‐based structural workflow that explicitly separates syn‐rift fault systems by relative chronology, hierarchical order and analytical scale prior to kinematic analysis, and (2) use that workflow to evaluate how rift obliquity and coaxiality vary through successive rifting stages. The approach integrates 3D seismic interpretation of fault geometry with stratigraphic truncation and cross‐cutting relationships. Fault systems and stratigraphic units are classified hierarchically and then analysed using kinematically constrained paleostress inversion. Rift obliquity ( λ ) is defined as the angular relationship between extension direction and rift trend, whereas rift coaxiality (Θ) expresses the degree to which successive deformation phases share a common principal deformation axis. The workflow documents a non‐monotonic evolution of rift obliquity across rifting stages. Early stretching is characterised by relatively high obliquity and low‐to‐moderate coaxiality, consistent with distributed deformation and strong influence of inherited structural fabrics. During the necking stage, deformation reorganises into a near‐orthogonal and highly coaxial configuration, interpreted as the most kinematically efficient phase of rifting on the outer proximal margin. As rifting progresses, obliquity decreases overall, but its expression becomes strongly dependent on scale and hierarchy: higher‐order fault systems preferentially record basinward trends, while lower‐order structures keep greater freedom to adapt locally through linkage, segmentation and relay development. Rift obliquity and coaxiality are not scale‐invariant properties. Basin‐scale kinematic trends may coexist with pronounced local variability, and non‐coaxial deformation can develop without major rotations of the regional stress field. By forcing an explicit separation of fault systems by time, hierarchy and scale, the proposed workflow provides a transferable framework for comparative kinematic analysis in other polyphase rifted margins where seismic interpretation is the primary constraint. Key limitations include uncertainties in plate‐kinematic reconstructions, seismic resolution, fault classification and the non‐uniqueness of palaeostress solutions; conversely, the main value of the method lies in resolving relative temporal trends and scale‐dependent behaviour rather than defining a single basin‐wide obliquity value.

Identifying gas hydrates and associated bottom simulating reflectors (BSRs) in seismic-reflection data requires the use of varied geophysical methods. Re-processed seismic data can primarily highlight seafloor features, but still show inherent signal limitations when resolving small-scale geological features. In contrast, seismic attributes applied to re-processed data have been successfully used in the recognition of hydrocarbon reservoirs. This work tests and applies an integrated seismic-attribute workflow for BSR mapping and qualitative interpretation of BSR-related anomalies, including those reflections commonly interpreted as representing free-gas beneath the BSR in the Makran Accretionary Wedge, offshore Pakistan. Seismic attributes were applied to the resolution-enhanced (re-processed) profile SO122-04a after a structure-oriented data conditioning that used dip-steered median filtering. They were followed by the extraction of amplitude attributes including Pseudo-Relief and Square-Root-of-Energy, and frequency decomposition including Fast Fourier Transform (FFT) and Continuous Wavelet Transform (CWT) evaluated at 20, 40, and 60 Hz. The results in this work show that Pseudo-Relief emphasizes the geometric expression of seismic anomalies and BSRs by illuminating their curvature and shape, while Square-Root-of-Energy highlights spatial variations in reflection energy across BSR intervals. FFTs and CWTs show comparatively stronger amplitude expression of BSRs and underlying reflections in the 40 and 60 Hz frequency bands. Finally, RGB color blending aids the visual identification of BSR-related anomaly zones (indicators of potential hydrate/free-gas systems), further supporting attribute-based mapping for the interpretation of BSR-related anomalies. Interpretations are qualitative in the absence of independent calibration data.

The interpretation of deep 2D seismic profiles from the central Adriatic foreland of the External Dinarides in the area of the islands of Vis and Jabuka (Croatia), reveals a complex Mesozoic platform-to-basin architecture, and Cenozoic structural and sedimentary system developed on top of the central part of the Adriatic microplate (Adria). Tectonic subsidence and thick Paleogene to Neogene sedimentary loading in the latest Dinaric foredeep probably initially mobilized buried Middle Triassic evaporites from the proximal to distal foreland. Miocene tectonic is characterized by basement-rooted positive flower structures, pop-up blocks, and upward-diverging fault splays, diagnostic of a transpressional tectonic regime.The crustal-scale Quaternary subvertical faults without apparent vertical throw are associated with positive and negative structures along the strike. In the overlying sedimentary cover, localized normal faulting and extensional arrays overprint transpressional structures, interpreted as gravitational collapse above pop-up blocks, roof collapse above ascending diapirs, and lateral collapse within a mechanically decoupled cover. The positive structures are associated with the Quaternary salt diapirs, some of which are still active. However, it is not clear which faults are inducing regional seismicity.Instrumental seismicity is moderate to strong (up to M>5), shallow (≈5–15 km) and spatially clustered around the diapiric structures. Focal‑mechanism solutions predominantly indicate reverse to reverse–oblique faulting, yet the nodal planes do not clearly coincide with any single reverse fault imaged on 2D profiles, and many hypocenters project within or immediately above active salt diapirs. These observations suggest that salt diapirs act as mechanical and geometric controllers that focus stress and localize brittle failure on surrounding basement‑rooted faults, rather than being the primary source of seismic energy, which is difficult to reconcile with the seismic moment of M>5 events if salt flow alone were responsible.Active salt structures are characterized by long stems and relatively small surface expressions that are aligned along Quaternary faults. Their geometry, disconnection with original depth of the Triassic evaporites, and limited lateral extent, indicate tectonic extrusion of deep evaporites. Variations and segmentation along strike, suggest localized strain and strong structural control on diapir rise. Overall, these observations indicate that diapir growth and surface expression are controlled by the interaction between deep shear zones, active faulting, and a mechanically decoupled overburden. Within this framework, seismicity reflects the interaction between deep shear zones, evaporite mobilization and upper‑crustal faulting, highlighting the need to re‑evaluate focal mechanisms with improved 3D velocity models and to explicitly incorporate salt‑controlled structures into seismic‑hazard assessments for the region.“This work was supported by Croatian Science Foundation project SALTECTA (HRZZ-IP-2024-05-2957).”Keywords: Central Adriatic Sea, 2D seismic profiles, Transpressional deformation, Salt diapirs, Active tectonics, Seismicity.

Tectonic deformation along the External Dinarides fold-and-thrust belt is slow, with transpressional crustal strain redistributed along multiple faults. Some of these faults reach the surface along the NE Adriatic coast as part of the strike-slip Dinaric Fault System (DFS). This work uses new high-resolution sub-bottom seismic data to characterize the geodynamic significance of active surface deformation in the offshore sector of the Kvarner area, Croatia. Seismic profiles reveal gentle folding in early Quaternary strata that is associated with contractional deformation in the Rijeka Bay; yet, active faults are documented only in narrow zones along the DFS, and specifically in the Vinodol and Velebit channels. Fault Mechanism Solutions (FMS) confirm that a strike-slip tectonic regime exists in the study area, but the strike of surface faults and FMS data are discrepant, probably as a result of strain dissipation along (creeping? ) faults whose geodynamic response differs from deep-rooted seismogenic structures. This differing geodynamic response causes important caveats when linking surface deformation to deeper seismogenic structures which are, offshore Kvarner, either blind structures or currently deforming under distinct stress conditions to near-surface faults. Crucially, this work presents the first geological evidence for active faulting along the DFS in Croatia, a piece of information deemed critical for future geohazard assessments.

High‐resolution 3D seismic reflection data, structural interpretations and expansion index analyses are combined in this work to explain the mechanisms that drove a newly discovered shift from extensional to strike‐slip tectonics in the central Mediterranean region. In the Crotone Basin, Early Pliocene extension predominated at first as proven by the nucleation of N‐ to NE‐striking normal faults bounding half‐graben basins and tilt blocks. Fault length reached ∼13 km, with associated half‐grabens being 5–8 km wide and up to 2.5 s two‐way time deep. Extensional tectonics at this stage followed tectonic collision between the Calabrian margin and the Apulian foreland; the removal of dense lithospheric mantle induced sharp elevation gradients and a rapid uplift of continental crust in the study area, promoting isostatic imbalances that ultimately led to extensional orogenic collapse. This same phase of extension was accompanied by the reactivation of inherited fault systems, which occurred together with the forward migration of the Calabrian Arc and oceanization of the Tyrrhenian Sea. Conversely, normal‐oblique to strike‐slip faulting has predominated offshore Crotone since the Late Pliocene as recorded by the development of elongated (up to ∼22 km long) and narrow (∼3 km wide) NW‐trending pull‐apart basins. Structural styles have since then been influenced by rheological contrasts between the continental Apulian foreland and Ionian oceanic lithosphere, which activated a broad WNW‐striking shear corridor. As a corollary of this work, modern structural and kinematic evidence indicates that fault segments within this shear corridor are arranged in an en echelon geometry and act as conjugate structures accommodating the progressive fragmentation of the overriding Apulian plate. On a broader scale of analysis, the transition from pure extension to strike‐slip tectonics documented offshore Crotone is associated with the differential subduction of heterogeneous foreland domains, a phenomenon that reflects the dynamic evolution of the central Mediterranean backarc system as a whole.

Northern Egypt and its Western Desert region are hydrocarbon provinces that record important Mesozoic extension, yet Jurassic and older synrift strata are still poorly characterized in these two areas, particularly in the onshore Shushan Basin. This work uses seismic-reflection data tied to borehole and geochemical data to investigate three main Jurassic synrift seismic and depositional megasequences in the Shushan Basin: (1) a Lower Jurassic retrogressive megasequence; (2) a Middle Jurassic prograding megasequence; and (3) an Upper Jurassic retrogressive megasequence. These megasequences, defined for the first time in this work, accompanied Late Triassic–Early Cretaceous tectonic extension, with deposition occurring in proximal environments such as rivers, lakes and deltas. Terrigenous organic matter was preserved over long periods of time within clay-rich source intervals, as confirmed via organic geochemical analyses. Significantly, the presence of Type II and Type III kerogen, and a total organic carbon content of up to 3.91% suggest good hydrocarbon source-rock potential in specific Jurassic intervals. One-dimensional burial models suggest that, with sufficient burial, these source intervals generated oil and gas with a recorded maximum yield in the Early Miocene. As a corollary, this work indicates that conventional and unconventional hydrocarbon exploration targets exist in the Shushan Basin. The results show Middle Jurassic shale-rich intervals to be prime tight-gas targets, while Upper Jurassic carbonate units are promising conventional reservoirs in both the central and southern parts of the basin. The high formation temperatures recorded show that geothermal options are also feasible for deep wells, expanding the economic importance of northern Egypt.

Overpressure is developed in both the reservoirs and source rocks of the Huangliu Formation (Yinggehai Basin, South China Sea), with pressure coefficients reaching up to 2.31. This study investigates the mechanisms responsible for overpressure in the source rocks of the Huangliu Formation and reconstructs their temporal evolution. Overpressured mudstones have anomalously high acoustic velocity and low resistivity values. However, the absence of low density values indicates that disequilibrium compaction is not responsible for the observed overpressure. The source rocks in this formation predominantly contain Type III kerogen (gas-prone), with total organic carbon values ranging from 0.4 to 2.56% and with an average value of 0.79%. Overpressured mudstones are buried at depths above 3300–4300 m, and subjected to formation temperatures ranging from 135 to 200°C and the relevant vitrinite reflectance ( R _o ) of 0.7–1.57%. Models of maturity and hydrocarbon generation history show that mudstones started to become overpressured at 3.5 Ma and that pore pressure is still increasing. This study provides new insights revealing that hydrocarbon generation, rather than disequilibrium compaction, is the primary mechanism driving overpressure development despite the low organic matter content of the source rocks.