Basin Research

Chao, Peng; Manatschal, Gianreto; Chenin, Pauline; Ren, Jianye

doi: 10.1111/bre.70103pmid: N/A

Seaward‐dipping sequences (SDS) are typically observed in sediment‐driven progradation of slope deposits in post‐rift sequences, or along magma‐rich rifted margins, where they are primarily formed by subaerial lava flows and referred to as seaward dipping reflections (SDRs). However, new seismic reflection data from the sediment‐rich northwestern South China Sea (NW‐SCS) reveal the existence of SDS in sediment‐rich syn‐rift sequences, here referred to as syn‐rift sedimentary SDS. Based on a detailed tectono‐stratigraphic analysis, we describe how these syn‐rift sedimentary SDS differ from magmatic SDRs and propose a conceptual model for their formation. We show that the formation of these sequences is most likely controlled by a combination of high sediment supply rates, rapid subsidence and creation of horizontal accommodation space, first along large‐offset detachment faults and later, during breakup, by magmatic accretion. While inner magmatic SDRs typically form in subaerial conditions above continent‐dipping faults, we suggest that syn‐rift sedimentary SDS can derive from turbiditic flows in a relatively deep‐water environment above oceanward‐dipping detachment faults and/or interfinger with magmatic additions. Finally, we discuss the implications of syn‐rift sedimentary SDS for the interpretation of rifted margins in general.

Diego, Bigi; Stefano, Lugli; Vinicio, Manzi; Marco, Roveri; Ibrahim, Milushi

doi: 10.1111/bre.70096pmid: N/A

We reconstructed the geological evolution of the Albanides during the Messinian salinity crisis (MSC), based on the integration of outcrop and subsurface data from both onshore (peri‐Adriatic depression, Albania) and offshore (Southern Adriatic Basin) settings. The lowermost MSC deposit consists of primary bottom‐grown gypsum accumulated in marginal basins (Rubjekë, Durres inland; Guri i Cifutit, Vlora) of the peri‐Adriatic depression. Facies analysis and Sr. isotope signature allow correlating these deposits with the Primary Lower Gypsum unit (PLG). This unit is truncated on top by an erosional surface that can be correlated in deeper settings (Currilla, Durres coast; Kavaje) with a sharp surface separating evaporite‐free, organic‐rich, and barren shales below from a clastic evaporite unit above. The unconformity can be regarded as the Messinian Erosional Surface and the clastic evaporites as the local expression of the Resedimented Lower Gypsum (RLG). Seismic and geophysical logs allow following this unit offshore in a WNW direction for hundreds of kilometres. While in the marginal settings the PLG are overlain by marine Pliocene deposits, in the deeper settings (Currilla) the RLG unit is overlain by thick terrigenous deposits that can be subdivided into a lower finer‐grained barren shale unit followed upward by a rhythmic alternation of conglomerate or sandstone bodies and shales. The uppermost portion of this unit contains a typical Paratethyan hypohaline faunal assemblage yielding a depleted Sr. signature and thus referable to the Lago‐mare unit, which records the final stage of the MSC. In turn, these deposits are followed by Zanclean open‐marine sediments. These findings are in good agreement with the 3‐stage model of the MSC and enable the reconstruction of basin‐scale correlations from the thrust‐top and foredeep basins of the Albanides and the Apennines, through the Adria foreland.

Reat Wersan, Ellen; Johnson, Cari; Morris, Emma A.; Wickens, H. DeVille

doi: 10.1111/bre.70083pmid: N/A

A low‐gradient shelf‐edge delta system preserved at the Katjiesberg outcrop in the northern Tanqua Karoo depocenter (South Africa) records the evolution from shelf‐ to slope‐depositional processes in a fine‐grained sandstone dominated system. Lateral and vertical facies associated with slumping and other soft‐sediment deformation features at near seismic scale (~1 km laterally, ~100 m vertically) are documented. Stratigraphic correlations of these units using measured sections and ~3 km of digital outcrop models document the stratigraphic position of two shelf‐edge inflection points, which implies progradation of the shelf‐edge. Progradation and aggradation of detached slump deposits and their transition into dominantly in situ deformation features are consistently representative of the evolution from slope‐to‐shelf through time. The exposed Permian–Triassic Kookfontein Formation prodelta/slope succession at Katjiesberg is likely a time‐correlative deposit to clinothem cycles previously described 10s of km up depositional‐dip to the southwest. Katjiesberg represents the more distal expression of these cyclothems in the lower Kookfontein Formation, whereas the upper cycles are interpreted as collapse‐dominated clinothems that are overlain by basinward prograding mouthbar deposits of the Waterford Formation. This study highlights intra‐basinal process regime variability and facies expressions within a preserved shelf‐edge delta system. Results underscore the role of slump features in characterising clinothems and signalling clinothem rollover, which is particularly useful in low‐gradient systems with subtle clinothem geometry. The characterisation of low‐gradient clinothem geometries and variability in this shelf‐edge delta system improves our understanding of shelf‐margin accretion and deepwater sediment delivery across the shelf and slope.

Adepehin, Ekundayo J.; Fong, Yi N.; Garzanti, Eduardo; Arifin, Hariri M.

doi: 10.1111/bre.70099pmid: N/A

Petrographic, mineralogical and geochemical analyses and 803 published detrital zircon U–Pb ages are here integrated to provide the first quantitative provenance analysis of the Oligocene‐Miocene Nyalau Formation in the Sarawak Basin foreland basin, northwest Borneo. Statistical unmixing reveals that simple two‐source models are insufficient: three distinct sources contributed sediment—the Malay‐Thai Peninsula (58%), the Rajang fold‐thrust belt (31%) and a previously unrecognised component (11%) characterised by syn‐depositional Oligocene‐Miocene volcanic zircons and Neoproterozoic populations absent from the other two established sources. This third source represents contemporaneous magmatic input plus recycled cratonic material from unexposed Bornean basement. Long‐distance axial drainage from the Malay‐Thai Peninsula dominated over proximal orogenic input from the Rajang fold‐thrust belt. Compositional variations record coupled tectonic‐climatic controls: quartz‐rich intervals with high ZTR indices reflect extensive recycling coupled with prolonged weathering, whereas lithic‐rich intervals indicate enhanced transverse input plausibly modulated by relative sea‐level and monsoonal discharge variability. This quantitative three‐source framework demonstrates that statistical provenance unmixing can reveal cryptic sediment contributors missed by binary mixing models, providing critical insights into tropical foreland basin evolution during major Oligocene‐Miocene geodynamic reorganisation.

Zhang, Wei; Wang, Junhui; Li, Zhuang; Tao, Gesi; Li, Li; Xia, Ranran

doi: 10.1111/bre.70092pmid: N/A

In conventional sequence stratigraphy, it is commonly believed that transgression occurs simultaneously across the sedimentary basin experiencing relative sea‐level (RSL) rise. As a consequence, the maximum flooding surface is widely utilised as a quasi‐isochronous chronostratigraphic marker for regional stratigraphic correlation. The concept of shoreline autoretreat demonstrates that the transgression may occur after a precursory regression. How long the precursory regression would last depends on external forcings including the rate of sediment supply (qs) and rate of RSL rise (Rrsl) and slope features of the basin. This means within a given basin, the onset of transgression varies in locations with different sediment supply rates and/or slope features. This study aims to analyse the influencing factors of the occurrence time of transgression in dual‐provenance basins through theoretical modelling and two‐dimensional flume experiments. To investigate these factors, two series of tank experiments were designed. The first series is supply‐modulated where the two provenances were different in qs, while the basin slope condition were kept the same. The second series is modulaed where the two provenances varied in hinterland slopes (γ) while qs were kept the same. Each series included 2 or 3 runs with different multiples of Rrsl or qs. Furthermore, a reference run was performed where the two provenances were identical in both qs and γ. The results reveal that: (1) qs and Rrsl have similar effect on transgression. As qs increases, the timing of transgression is delayed, while an increase in Rrsl accelerates its occurrence. Both factors affect the timing of transgression by altering the size of the river‐delta system. (2) The occurrence of transgression is closely related to the size of the river‐delta system. Guided by the autoretreat mechanism, the fluvial‐deltaic system maintains its progradational trend during a constant RSL rise, provided it has not yet reached its critical dimensions. A transgressive retreat is fundamentally postponed until the delta evolves to exceed this intrinsic spatial threshold, at which point the required sediment volume for progradation outstrips the supply. Only when the river‐delta size exceeds the critical size does transgression take place. The critical size is controlled by a combination of qs, Rrsl, and basin slope. (3) Hinterland slope (γ) affects subaerial and subaqueous allocations of sediment. Larger γ result in a reduction of subaerial allocations of sediment. As a result, the alluvial realm expands slower but the aggradation rate is higher, by which transgression is delayed. The Canterbury Plain in New Zealand serves as a potential example of asynchronous transgression in a basin with varying provenance. Based on an understanding of autostratigraphic processes, these findings offer a framework for explaining the anisochronicity of transgression in natural basins and provide a novel perspective for reconstructing basin evolution and stratigraphic analysis.

Saul, Deron; Nicholson, Uisdean

doi: 10.1111/bre.70097pmid: N/A

The Guyana Basin developed in an evolving tectonic setting, but a lack of subsurface data has limited understanding of its tectonic and sedimentary evolution through time. This study uses extensive, newly available 2D seismic reflection and exploration well data to develop a regional tectonostratigraphic framework, to reconstruct sediment accumulation and constrain sediment routing to the basin through time. Five megasequences (MS‐0 to MS‐4; oldest to youngest) are defined, each representing a distinct phase of basin fill. MS‐0 corresponds to the pre‐ and syn‐rift phases of the Central Atlantic rift, marked by folded volcano‐sedimentary units. MS‐1 (Middle Jurassic–Aptian) represents the post‐rift phase of the Central Atlantic, characterised by low sedimentation rates and isolated depocenters likely fed by nearby continental sources from the Guyana margin, and possibly adjacent conjugate margins in North America and Africa. MS‐2 (Aptian–Albian) represents the Equatorial Atlantic syn‐rift and transform phase, marked by the development of the Equatorial Atlantic Fracture Zone (EAFZ) and the emergence of a southeastern slope depocenter. MS‐3 (Albian–Middle Miocene) corresponds to the Equatorial Atlantic passive margin phase of the basin, with sediment transported through large canyon systems, likely indicating increased riverine flux from the Guyana margin. MS‐4 (Upper Miocene–Recent) reflects ongoing passive margin sedimentation and the development of a fold‐and‐thrust belt in the northwestern basin due to the collision between the Caribbean and South American plates. About 41% of the total sediments of the Guyana Basin were deposited in the last ~11.6 Myr, driven by a ~40 MTa−1 sediment flux primarily from the Amazon River–Guiana Current system. This order of magnitude increase in sedimentation rate in the Miocene corresponds with the onset of widespread mass transport deposits, indicating that rapid sedimentation and disequilibrium compaction preconditioned the continental slope for repeated failure. This has important implications for slope stability, with large‐volume submarine landslides forming a potentially significant landslide and tsunami hazard for subsea infrastructure and coastal populations.

doi: 10.1111/bre.70093pmid: N/A

Chebli, Hala; Hudec, Michael. R.; Benarchid, Asmae; Peel, Frank; Gillian, Apps; Chakiri, Said

doi: 10.1111/bre.70094pmid: N/A

Salt‐bearing passive margins represent some of the most structurally complex and economically significant hydrocarbon provinces worldwide. However, these margins are often characterised by substantial uncertainties related to crustal and syn‐rift basin architecture and suprasalt tectonic evolution. The Essaouira Basin, a salt‐bearing passive margin and a promising hydrocarbon province encompassing all essential elements of a petroleum system, remains geologically complex, with unresolved questions regarding its post‐salt gravity‐driven deformation and overall tectonic evolution. This study presents an integrated analysis of the post‐salt evolution of the Essaouira Basin, utilising 2D and 3D seismic reflection and well data combined with structural restoration. Our results indicate that salt deposition was strongly controlled by basement structural inheritance, evidenced by abrupt lateral variations in salt thickness across the basin. The evolution of the basin proceeded through three distinct phases: (1) An initial phase dominated by gravity‐driven deformation, strongly influenced by the Cap Ghir Graben, which functioned as a localised depocenter and disrupted downdip salt flow, resulting in the development of two linked kinematic systems. This early configuration led to a distribution of structures and domains that differs from conventional salt‐bearing passive margins; (2) A second phase characterised by halokinesis, primarily manifested through passive diapirism, driven by differential sedimentary loading during the Early Cretaceous; and (3) A final phase, commencing in the Late Cretaceous, marked by contractional deformation related to far‐field compressional stresses associated with the Atlas orogeny. Additionally, Late Cenozoic shelf uplift is attributed to plume‐related mantle upwelling. This study highlights the role of pre‐existing rift architecture and subsequent tectonic events in shaping the Essaouira Basin's complex salt tectonics, providing new insights into the evolution of salt‐bearing passive margins.

Juárez‐Zúñiga, Sandra; Stockli, Daniel F.; Johnson, Benjamin; Lawton, Timothy F.

doi: 10.1111/bre.70098pmid: N/A

The Marfa Basin in West Texas is a late Palaeozoic synorogenic depocenter associated with regional deformation linked to the Ancestral Rocky Mountains (ARM) and Ouachita–Marathon–Sonora (OMS) orogenies in southwestern Laurentia. Basin strata range in age from Middle Pennsylvanian to the middle Permian and include the Cieneguita, Alta, Pinto Canyon, Rose Mine and Mina Grande Formations. Sandstone petrography and detrital zircon (DZ) U–Pb and (U–Th)/He double dating data from these strata reveal three tectonically driven sedimentation stages: syntectonic ARM deposition, progressive OMS foredeep deposition and an orogenic transition. The Cieneguita and lower part of the Alta Formations exhibit a Mesoproterozoic DZ age signature (~1318 and ~1076 Ma age peaks) and quartzo‐feldspathic sandstone compositions sourced from the adjacent ARM‐related Diablo Platform basement uplift in the Middle Pennsylvanian to earliest Permian. In contrast, the upper part of the Alta Formation, as well as the Pinto Canyon and Rose Mine Formations, have peri‐Gondwanan DZ age signatures, with Mesoproterozoic (~1069–1036 Ma age peaks), Neoproterozoic–Cambrian (~700–490 Ma) and Palaeozoic (~490–300 Ma) age modes and litho‐quartzose sandstone compositions derived from the OMS fold‐and‐thrust belt and orogenic hinterland during the early to middle Permian. The lower to middle parts of the Alta Formation have alternating DZ age signatures and sandstone compositions from both ARM and OMS sources, revealing that the transition in the sediment supply occurred during the middle Wolfcampian. This transition was not characterised by source mixing, but rather by sediment interfingering alternately sourced from the Diablo Platform uplift and the advancing OMS belt. These observations are confirmed by the DZ He ages, which reveal distinct cooling histories for both source terranes. These results document a switch from ARM‐ to OMS‐related syntectonic deposition in southwestern Laurentia during the early Permian, demonstrating that ARM‐driven deformation largely preceded the continental collision along the Marathon segment of the OMS orogen.

Castro, David L.; Oliveira, Diógenes C.; Melo, Germano; Ramos, Gilsijane V.; Melo, Alanny C. C.; Rostirolla, Sidnei P.

doi: 10.1111/bre.70101pmid: N/A

This study promotes a comprehensive geophysical mapping of the Potiguar Basin Precambrian basement with unprecedented detail, using thermomechanical analysis of the lithosphere, advanced anomaly enhancement techniques, an unsupervised semi‐automatic mapping method (SOM) and 2D/3D joint magnetic‐gravity modelling constrained by seismic and well data. This Early Cretaceous multiphase marginal basin, located at the northeastern end of the Brazilian transform margin of the Equatorial Atlantic, conceals in its onshore portion an aborted rift overlain by thin post‐rift deposition. The combined analysis of Curie‐Point Depth, Effective Elastic Thickness and Moho relief reveals six distinct crustal domains, providing a refined understanding of the lithospheric structure and its response to the plate‐driven motion that caused the crustal thinning and rifting. Analysis of magnetic and gravity patterns, lineaments and SOM populations integrated with magnetic susceptibility‐density models and key geophysical transects over the study area demonstrates the complex Precambrian basement grain dominated by intensively deformed shear zones and sets of grabens and horsts within the rifted zone. Our results highlight that the Potiguar Rift intricate internal architecture preserves evidence of the strong structural control exerted by the pre‐existing structural framework on the nucleation and evolution of this intracratonic rift, and its subsequent abandonment. This geological setting emphasizes the Potiguar Basin as a key case study of tectonic inheritance role at the lithospheric, continental, basinal, and fault‐scales.