Basin Research - Volume 34, Issue 5, 2022

The stratigraphic succession in the San Vincenzo Gorge (Saccense Domain, western Sicily) documents deposition on a vast pelagic carbonate platform, the Sciacca Plateau, during the Middle and Late Jurassic. This succession caps a peritidal limestone (Inici Formation), which underwent extension during the Western Tethyan Early Jurassic rift phase, and displays a set of unique features, which have never been previously reported on a Tethyan drowned platform. The upper part of the Bositra limestone (late Bajocian‐early Oxfordian p.p.) comprises elongate convex‐up, mound‐shaped bodies, made of thin‐shelled bivalve wacke‐ to grainstone, a few tens of metres across and producing a topographic relief of up to 10 m. Planar beds within the mound cores are seen to thin out laterally with tangential downlaps along sections perpendicular to the mounds' longer axes, and the mounds are in lateral association with concave‐up bedsets. Following halt of the Bositra‐dominated deposition and demise of mound accretion, the draping units inherited an antiformal geometry. The mounds are interpreted as being part of a sediment drift, produced by bottom currents sweeping the Plateau top, the source areas being sediment‐depleted sectors now documented by extremely condensed and hiatus‐ridden sections, with parallel‐sided beds. Following draping and partial levelling of the submarine relief by the Knobbly limestone (?middle Oxfordian/early Kimmeridgian‐late Kimmeridgian), the Coquina limestone is locally a thick (>20 m) ammonite/brachiopod rudstone (Tithonian p.p.). This unit displays evidence for lateral accretion, with large‐scale clinoforms dipping up to 12°, and is interpreted as a mud‐poor, bioclastic‐gravel drift, with the action of bottom currents being apparently linked with a bloom of cephalopods. This is an early‐cemented deposit, where clotted, micropeloidal fabrics document the calcification of microbial communities and are followed by growth of early diagenetic fibrous calcite. The description and interpretation of the mounded Bositra limestone and of the clinostratified Tithonian limestone are the main focus of this paper. The San Vincenzo Gorge outcrop displays similarities with pelagic shelves, like the Upper Chalk basin of northern Europe.

Mechanical accumulations of thin Bositra shells form mounds, with complex internal geometries (yellow dots), on the flat top of a drowned carbonate platform, lending an antiformal geometry to their Kimmeridgian–Tithonian drape (above dashed blue line).

Atolls are faithful recorders helping us understand eustatic variations, the evolution of carbonate production through time, and changes in magmatic hotspots activity. Several early Cretaceous Mid‐Pacific atolls were previously investigated through ocean drilling, but due to the low quality of vintage seismic data available, few spatial constraints exist on their stratigraphic evolution and large‐scale diagenesis. Here, we present results from an integrated core‐log‐seismic study at Resolution Guyot and comparison with modern and ancient analogues. We identify six seismic‐stratigraphic units: (1) platform initiation with aggradation and backstepping through the Hauterivian which ended by platform emersion; (2) reflooding of the platform with progradation and aggradation through the Barremian till the early‐Aptian when ocean anoxic event 1a resulted in incipient drowning; (3) platform backstepping till the mid‐Aptian when the platform shifted to progradation and aggradation till the mid‐Albian; (4) platform emersion; (5) reflooding with backstepping ending at the latest‐Albian by platform emersion; and (6) final drowning. The stratigraphic surfaces bounding these units are coeval with some of the Cretaceous eustatic events, which suggest an eustatic control on the evolution of this atoll and confirm that several previously reported sea‐level variations in the early Cretaceous are driven by eustasy. Changes in subsidence and carbonate production rates and suspected later magmatism have also impacted the stratigraphic evolution. The suspected later magmatism could lead to environmental perturbations and potentially platform demise. Contrary to previous studies, we identify two emersion events during the mid‐ and late‐Albian which resulted in intensive meteoric dissolution and karstification. The platform margin syndepositional fractures interacted with the subaerial exposure events by focusing the dissolution which formed vertically stacked flank‐margin fracture‐cave system. The study gives a unique insight into the interplay between eustasy, subsidence, and volcanic activity(ies) on long‐term evolution of early Cretaceous shallow‐marine carbonates. It also documents the impact and distribution of hypogenic and epigenic fluid‐flow in atolls serving as an analogue for isolated carbonate platforms.

Seismic‐stratigraphic analysis of Resolution Guyot as a prime examples of the Cretaceous Mid‐Pacific atolls revealed controls from the Cretaceous eustasy on the evolution and karstification of the Cretaceous Mid‐Pacific atolls along with other factors including changes in subsidence and production rates and later magmatic activity(ies).

Late Quaternary syn‐rift basinal deposits in the Gulf of Corinth, Greece, are analysed using IODP Expedition 381 boreholes. Stratigraphic packages of mud‐dominated deposits record distinct hydrological conditions related to global sea‐level interacting with highs at the ends of the rift, highlight rift segment boundaries as controls on stratigraphy in rifts.

Syn‐rift deep‐water muds and mudstones preserve a relatively complete stratigraphic record of tectonic and climatic events. This paper investigates mud‐dominated deposits and stratigraphy using core from International Ocean Discovery Program (IODP) Expedition 381 sites M0078 and M0079 in the Gulf of Corinth, Greece. Millimetre‐scale logging defined several bed types: homogeneous and laminated mud beds, bioturbated beds, a variety of graded beds, and rare matrix‐supported conglomerates and slumps. Homogeneous muds and light grey to black laminated muds record deposition from distal, waning low density turbidity currents and terminal mud‐rich quasi‐laminar or laminar plug flows. Graded beds, interpreted as turbidites, range from beds several millimetre to a few centimetres of mud with silt to fine sand bases, to metre‐scale mud beds with coarser sand and pebble bases. Conglomerate and slumped beds record cohesive debris flows, transitional flows and slope failure. Three stratal package types are distinguished: bioturbated, bedded and laminated, recording distinct hydrological conditions. Bioturbated packages record interglacial marine conditions with well oxygenated waters. Bedded packages record hemipelagic processes and low energy density underflows in a mainly dysoxic, stratified, lacustrine setting (glacial phases). In laminated packages, white mm‐scale laminae of calcite or aragonite from varved, hemipelagic sediments demonstrating seasonal variability in a dysoxic non‐marine or transitional setting. Rift stratigraphy is linked to eustatically controlled connections to the global ocean across rift segment boundaries. The ca. 780 to 330 ka succession is dominated by laminated packages with thin bioturbated packages and distinct conglomerates and slumps, suggesting high sills, making ocean connections brief and transitional to lacustrine conditions prolonged. The ca. 330 ka to present succession shows well developed bioturbated and bedded packages, separated by thin laminated packages, suggesting brief transitions and well‐developed marine conditions due to lower sills. Results indicate that structurally controlled rift segment boundaries exert a first‐order control on syn‐rift stratigraphic evolution, with fault segment growth and linkage driving intra‐rift facies and sequence variability.

Petrologic and instrumental analyses were used to reconstruct the characteristics and timing of vein‐forming fluids in the Ordovician limestones in the Shunbei area, Tarim Basin. In light of the study area's complex structural history, we then deciphered the structural diagenesis controlled by intra‐cratonic strike‐slip faulting. The coupling of brittle deformation and diagenesis (ie., fracturing and cementation) also provides new insight into the creation and persistence of open fractures in tight carbonate rocks.

The Ordovician fracture‐cavity reservoirs in the Shunbei area of the Tarim Basin, China, afford an exceptional opportunity to use petrological and geochemical data to investigate structural diagenesis in deep low‐porosity (‘tight’) carbonate rocks. We obtained the relative timings for the development of fracture veins using petrological and cathodoluminescence analyses of minerals from representative samples. Textural observations combined with geochemical data determined the source and timing of the mineral‐forming fluid. The conceptual model of the overall temporal evolutions of structure and fluid flow developed herein indicates that fluid flow is a consequence of strike‐slip fault activity and the local stress state. Strike‐slip faults control the development of fractured–vuggy reservoir space and provide driving force for fluid flow along and across layers. Simultaneously, the direction of fluid migration can be influenced by local stress conditions, while compressive stress may restrict fluid flow. Results of this study suggest that open fractures develop as a result of structural diagenesis, rather than resulting from a single structural factor. The findings of this study can be used to inform the exploration and exploitation of deeply buried faulted carbonate reservoirs worldwide.

Schematic evolution of the basin showing the salt deformation from Messinian to current times along two NW‐SE profiles across the central Algerian basin. The water level during the UU deposition is based on estimations from Heida et al. (2021) and Strzerzynski et al. (2021).

Field analogues illustrating the early stage of deformation of shortening structures in salt‐bearing orogenic fold‐and‐thrust belts are not yet well illustrated in literature. The relatively young Messinian salt of the Algerian basin could represent a good case example of such systems. The Algerian Basin is a deep‐water Miocene back‐arc basin including a layer of mobile Messinian evaporites up to 2 km thick. The Messinian salt was deposited in an already inverted basin, after its extensive stage. Its inversion initiated in the Tortonian, with a N‐NW shortening induced by the north‐westward motion of the African plate. In this study, we use new 2D multichannel seismic data to identify, classify and map salt structures throughout the central Algerian Basin and re‐assess its structural style. We interpret contractional salt tectonic structures, such as buckle folds, squeezed diapirs and related salt sheets as evidence of regional thick‐skinned shortening episodes. We conclude that horizontal displacement loading has driven salt deformation within the basin since its deposition. We also show spatial variations in the structural style of the central Algerian Basin, both along‐ and down‐dip. We demonstrate that the initial shortening‐related salt deformation in the late Messinian was focussed along the Algerian margin and later shifted outward toward the Balearic margin in the Plio‐Quaternary. The shifting of the deformation front is interpreted to be a result of the thickening and strengthening of the overburden. The second peak of deformation may have reactivated faults along the Emile‐Baudot escarpment with thick‐skinned deformation. We also observe a variation in the intensity of the salt deformation along the margin from SW to NE, which may be due to variable tectonic loading applied along the Algerian margin or the pre‐shortening distribution of salt.

The rift system of in the North of Campos Basin records two distinct rift phases (RP1 and RP2). The RP1 and therefore the onset of rifting is interpreted to have occurred in the Berriasian.

The Campos and Santos Basins have been a focus of subsurface studies since the discovery in 2006 of large accumulations of hydrocarbons in the Early Cretaceous rift and post‐rift strata below Aptian evaporites. In this study, regional 2D seismic lines, a 3D seismic survey and well data were interpreted to reconstruct the tectono‐stratigraphic evolution of the rift and post‐rift stages in the northern sector of the Campos Basin. Detailed 3D seismic interpretation and geological modelling were used to subdivide the pre‐salt sedimentary record. This revealed a diachronous strain distribution along the Guriri Fault System (GFS), a roughly NE‐SW striking fault‐bounded horst that was a focus of rift‐related deformation. The syn‐rift succession is interpreted to be the product of two episodes of rifting (RP1 and RP2) with contrasting fault activity patterns and lithostratigraphy. Volcaniclastics and coarse siliciclastics of RP1 were deposited under WNW‐ESE transtension that formed discontinuous half‐grabens followed by extensive erosion and tectonic inversion. Structurally controlled bioclastic rudstones and hybrid deposits characterize RP2 and were deposited in elongated half‐grabens that delimit the GFS horst, which developed under an NW‐SE extension. Deposition under increasingly less tectonically active transitional and post‐rift stages dominated by thermal subsidence gradually led to the healing of the rift‐related structural relief. Selective reactivation of rift faults testifies active tectonic inversion through compression from immediate post‐rift throughout evaporite deposition. These interpretations are put into the context of recent geochronological data of onshore dyke emplacement and the new age constraints for the end of deposition of the pre‐salt sequence. Therefore, we propose an earlier onset on rifting in the Campos Basin, at the Berriasian.

Reflectivity gaps in across hydrate related bottom simulating reflections induce uncertainty around large‐scale estimations of gas hydrate occurrence. Using two‐dimensional seismic data from the southern Hikurangi subduction margin, we present a new model that explains the cause of BSR gaps within synclinal structures. The new model may have wide appliciability in hydrate provinces with similar tectonic histories

Bottom simulating reflections (BSRs) interpreted in seismic data are one of the most used indicators for the presence of gas hydrates. In numerous hydrate provinces, including the Hikurangi margin, east of New Zealand, distinct and anomalous gaps in reflectivity punctuate otherwise continuous BSRs. We undertake a seismic stratigraphic and structural interpretation of a dense grid of two‐dimensional reflection seismic data to investigate possible causes of widespread BSR gaps that occur near the hinge area of synclines. We explain these BSR gaps with a tectono‐sedimentary model where sedimentation into accretionary wedge synclines leads to an upward migration of the base of gas hydrate stability with respect to stratigraphy, causing dissociation of gas hydrates to water and free gas. A trough‐shaped syncline's radially dipping beds promotes along‐strata, upward migration of gas away from the hinge area, incrementally depleting synclinal hinges of gas and resulting in a BSR gap or muted BSR. This model may be applicable to observed gaps in BSRs in tectonically active slope basins worldwide.

New field sedimentological observations, results from heavy mineral studies and detrital zircon U–Pb geochronology, together with conventional sandstone petrography reveals a series of provenance shifts related to the tectonic history of Sulawesi.

Neogene syn‐and post‐orogenic sedimentary rocks in Sulawesi are important to understand the history of collision of Australian continental crust with SE Asia. However, they have received relatively little attention, and have generally been considered to be molasse‐type deposits of similar characteristics across Sulawesi—the Celebes Molasse. New field sedimentological observations, results from heavy mineral studies and detrital zircon U–Pb geochronology, together with conventional sandstone petrography identify three important provenance shifts, that can be correlated with significant tectonic events and enable the reconstruction of the Neogene palaeogeography of SE Sulawesi. The first provenance shift was related to the Early Miocene collision of Australian crust and the North Sulawesi volcanic arc, accompanied by ophiolite emplacement in East Sulawesi, marked by a change from pre‐collision carbonates to ultramafic‐rich clastics of the Bungku Formation. A second change in the Late Miocene was marked by input of abundant metamorphic detritus including blueschists into the Pandua Formation indicating exhumation of Oligo‐Miocene subduction zone material. The third provenance change, of Mio‐Pliocene age, was from the ophiolite‐ and blueschist‐rich Pandua Formation to the quartz‐rich Langkowala Formation, and records blocking of the ophiolite debris pathways by the rise and progressive unroofing of low‐ to high‐grade metamorphic rocks. The Neogene sedimentary rocks of SE Sulawesi record Early Miocene collision and ophiolite emplacement, followed by extension which led to exhumation of Mesozoic and metamorphic rocks, driven by Banda subduction rollback.

The structure and tectonic evolution of the Cretaceous rift basins of southern Egypt are poorly understood. In this study, the tectonostratigraphy of the Komombo Basin has been determined using seismic, well and biostratigraphic data. The tectonostratigraphy of the basin is compared to the Kharit, Nuqra and Beni Suef basins in Egypt as well as Muglad Basin in Sudan. The Komombo Basin is a 58 km long, 28 km wide NW–SE trending half‐graben infilled with 2200 m of Berriasian‐Maastrichtian sediments and overlain by 400 m of Pliocene sediments. Four Berriasian to Maastrichtian syn‐rift and post‐rift sequences and three Pliocene channel systems of Nile sediments have been identified. Moreover, a series of normal faults, negative flower structures, reverse faults and folds are mapped in the basin. Backstripping reveals two rift phases during the Berriasian‐Barremian and Turonian‐Santonian, respectively. Additionally, the tectonic subsidence curves indicate that two major unconformities have occurred during the Aptian‐Albian and Maastrichtian‐Pliocene, which are correlated with a basement uplift during the Albian‐Cenomanian and the Oligocene‐Miocene flank uplift related to the opening of the Red Sea, respectively. The rift episodes are attributed to far‐field stress changes resulting from the initial opening of the South Atlantic and followed by the NW part of the African plate colliding and anticlockwise rotating into Europe. The highest β factors (1.20–1.11) for both rift phases are found at the centre of the basin. The rift phases thinned the crust from 32.5 to 28.2 km and 31.9 km in the depocenter and the western flank of the basin. The Komombo Basin has a similar rift history, stratigraphy and structural style to the Kharit, Nuqra and Mugland basins. All of these basins witnessed two major rift phases in the Early and Late Cretaceous, whereas the Beni Suef Basin encountered strike‐slip tectonic events in the Late Cretaceous.

The Komombo Basin is the only hydrocarbon productive basin in southern Egypt. However, no study has been carried out to compute the tectonic evolution and subsidence history of the basin. The tectonic subsidence curves indicate two rift phases during the Berriasian‐Barremian and Turonian‐Santonian, respectively. Furthermore, two major unconformities have been documented during the Aptian‐Albian and Maastrichtian‐Pliocene, respectively.

Numerical modeling results under the mud retention rates of (a) 0%, (b) 20%, and (c) 40%, and (d) shows how much more land can be built over 100 years with bottomset compared to one without bottomset (the modeling delta is scaled to the Wax Lake Delta conditions).

The loss of land in coastal regions is an emerging topic across the scientific community, as many countries struggle to minimize the consequences of an accelerating relative sea‐level rise. Various methods have been attempted to mitigate land loss, and river diversion for the Mississippi River Delta, which makes use of the natural river delta‐building process, has been proposed and significantly examined. Prior delta‐building models predicted possible ranges of new delta‐building rates and verified the feasibility of reduction in land loss on the Louisiana coast by river diversion by only considering the delta topset and foreset deposition without incorporating the muddy bottomsets because sand was regarded as the main delta‐building sediment, and mud was treated as washload. Since sand flux is significantly smaller than mud flux in most coastal rivers and muddy bottomsets are common in most deltas, it is critical to understand the depositional processes of mud in deltas. Here, we present the results of a coupled numerical modelling and flume experiment that includes a moving boundary at the foreset‐bottomset break in addition to the shoreline. We find that bottomset aggradation can accelerate the shoreline progradation by decreasing the foreset length (i.e., depth at the delta front). We also apply our model to a field scale based on parameters taken from the Wax Lake Delta. When 10%–50% of the mud supplied to the delta is retained in the bottomset, the subaerial delta area increases by 4.4%–25.4% compared to that in a delta with no bottomset accumulation. Therefore, considering the bottomset in land‐building modelling can provide more accurate predictions for a new land‐building area by river diversion.

The Pyrenees Mountains are a classic example of a doubly‐verging collisional orogenic system with flanking retro‐ and pro‐foreland basin systems. Previous bedrock and detrital geo‐/thermochronologic studies have observed magmatic and exhumation‐related ages that reflect a complex thermo‐tectonic evolution of the European and Iberian plate margins related to break‐up and assembly of the Gondwana, Pangea and Pyrenean‐Alpine orogenic cycles. This study integrates detrital zircon, rutile and apatite U‐Pb dating and, detrital zircon and apatite (U‐Th)/He dating from modern river sands from the northern and southern Pyrenees, with PECUBE thermokinematic modelling of bedrock cooling ages to simulate detrital age distributions in order to evaluate: (1) regional patterns in long‐term crustal processes associated with pre‐Pyrenean crustal shortening, crustal thinning and magmatism along the Iberian and European plate margin; (2) timing of regional cooling and inferred erosion related to Pyrenean orogenesis; and (3) the exhumation processes associated with post‐orogenic decay and erosion. Modern river multimineral detrital geo‐/thermochronometry results are consistent with previous bedrock thermal history models and records punctuated Variscan and Pyrenean cooling events in the pro‐wedge that contrasts with protracted Permian to Pliocene thermal history preserved in the retro‐wedge of the orogen. Detrital age distributions from PECUBE modelling predict the Pyrenean age component in both detrital apatite and zircon (U‐Th)/He age distributions, indicating the modelled exhumation patterns in the Axial Zone and Northern Pyrenean Zone can predict observed Pyrenean thermochronology ages. The presence of strong Pyrenean age peaks amongst the modern river sand and modelled detrital cooling age distributions suggests retro‐wedge deformation and exhumation remained active during the main phase of pro‐wedge activity and experienced significant orogenic decay. Isolated Miocene apatite He ages from the North Pyrenees modern river record post‐orogenic cooling, due to tectonic mode switch to extension and (or) climate‐driven enhanced exhumation.

Multi‐mineral geo‐/thermochronology of modern river sands sampled across the Pyrenees Mountains preserves composite crystallization, cooling, and metamorphic histories. New PECUBE 3D thermokinematic model provides a continuum of the time‐temperature paths across the entire Pyrenees orogen that is used to model detrital thermochronology age distributions.

Seafloor and subsurface view of the central Hikurangi Subduction Margin. This study documents numerous deep‐water sedimentary systems that have traversed this convergent margin slope from the Miocene to the present day, with implications for the tectonostratigraphic evolution of deep‐water fold and thrust belts.

Deep‐water sedimentation on active margins often entails complex sediment transport pathways through slope accommodation. Sedimentation in such settings is commonly differentiated into ‘fill and spill’ vs. ‘tortuous corridor’ models. To investigate the utility of these models in convergent settings 15,344 km² of 3D seismic data is used to investigate sedimentation and erosion patterns across the Hikurangi subduction margin. A series of thrust‐bound trench‐slope basins, each tens of kilometres long by kilometres wide, have been diachronously forming, filling and deforming through the Neogene until today. Five primary input points delivered sediment to the basins along the studied part of the margin. Channels display both axial and transverse orientations, the run‐out lengths of which vary temporally. At various times, relatively coarse‐grained sediment was trapped in the interior basins, occasionally then to be cannibalised during landsliding or erosion of growing structures. At other times, coarse‐grained sediment was bypassed to distal basins or the trench. Multiple sediment input points and occasionally tortuous sediment dispersal corridors result in the evolution of convoluted depositional systems, often with similar styles of sedimentation occurring contemporaneously in proximal and distal basins, contrary to simple models of basin fill. A hierarchy of controls on sediment distribution can be distinguished. At the highest level, sediment distribution is controlled by external factors, for example, glacio‐eustacy and tectonics. At basin scale, the interaction of sedimentary systems with local relief (e.g. evolving seafloor structures and landslides) dictates the location and style of deposition. At the lowest level, autocyclic factors (e.g. flow response to earlier deposits) influence the spatiotemporal variation in erosion and sedimentation. The complex interplay of these factors dictates whether basins were filling, spilling or some combination at any point in time, whilst basins that were filled and spilled may subsequently resume filling due to changes in the bounding conditions. Hence simple use of ‘fill and spill’ or ‘tortuous corridor’ models to tectonically active margins is not advised. Furthermore, as sedimentation may influence structure growth, constraining the controls on sediment distribution may improve understanding of the broader evolution of convergent margins and their resource distribution.