Basin Research最新文献

Development of brittle fracture zones as passages for fluid migration within the shallow crust results in substantial petrophysical and rheological changes that strongly influence deformation localisation, promoting reactivation at evolved inhomogeneities in the host rock. A natural example of multi-stage fault zone evolution with different generations of deformation elements and mode of silica cementation was investigated using combined structural, burial, micropetrographic, geochemical and geochronological analyses in a sandstone predating the main rifting phase. Deformation mechanisms progressively evolved from proto-cataclasis, through advanced cataclasis connected with inhomogeneous silica cementation, to siliceous fluid-enhanced slip along discrete fault planes or vein formation; all of these processes are well correlated with burial and volcanic phases. The established relationships allowed reconstruction of the evolutionary steps within the fault zones as the initially porous sediment was structurally and diagenetically hardened and then softened, and the geometry of the fault system changed during rifting. The age of silica-associated fracture systems (syn-tectonic silica cementation) is constrained by early type deformation bands (having the same pattern as silica-associated fractures) occurring in the ~15.3 Ma pyroclastic rocks bordering the sandstone. Silica precipitation can be related primarily to structurally controlled fluid pulses and rapid cooling as fluids pass through the propagating syn-rift fractures in an initially good siliciclastic aquifer. Such large-scale hydrothermal fluid migration, resulting in tens of km² siliceous cementation, was facilitated by the onset of volcanic activity. The accompanying general increase in fluid pressure may have led to the permutation of the maximum and the intermediate principal stress axes. As a result, the early syn-rift extension switched to a transtension during the main syn-rift phase. Meanwhile, vertical axis rotations also contributed to the change in the apparent stress field, resulting in the development of a fault pattern analogous to an oblique rift. The developed fault sets, with three characteristic orientations and frequent reactivation, may have formed in relation to an inherited structural weakness zone.

Quantifying sediment fluxes is an essential part of the Source-to-Sink approach in the understanding of sedimentary systems. However, the transfer of sediment from the source to the sink and the factors controlling it are still poorly understood. We focus on a small catchment coupled with its offshore deep-sea fan: the Sithas system (Gulf of Corinth, Greece). We restore the volume of sediment eroded in the catchment using geomorphic constraints; quantify the volume of sediment deposited in the offshore basin, after revising the age model; and calculate erosional fluxes using the BQART model. This allows for the comparison of the reconstructed fluxes of sediment eroded and deposited since 800 ka across the entire source-to-sink system. For the Sithas coupled catchment-deep-sea fan system, we show an increase in sedimentary fluxes both in erosion and deposition since 800 ka and particularly since 400 ka, where cyclic variations of ~120 kyr are recorded in erosion and deposition compartments. We suggest that the overall increase in flux results from a change in the catchment size due to the tectonic evolution of the region. The record of cyclic variations from 400 kyr in fluxes matches with the maturity of the system and with the intensification of glacial cycles and tectonic constraints migration. We also suggest that the discrepancy between erosion and deposition reflects a temporary storage between source and sink areas, probably along the coast. This has changed since 30 ka, introducing the last phase of evolution characterised by phased source and sink dynamics, suggesting a lack of temporary storage and a connection between river outlet and submarine canyon head. This study shows that sediment fluxes are controlled by the catchment's size as well as by climatic and tectonic factors and that even a small sedimentary system can be affected by temporary sediment storage.

The topographic growth of the Eastern Cordillera in the northern Andes of Colombia is a critical event in the tectonic and paleogeographic evolution of the western Amazon Basin. Documentation of early orogenic growth is enabled through multi-proxy provenance signatures recorded in the adjacent retro-foreland basin. In broken foreland basins, basement highs interrupt the lateral continuity of facies belts and potentially mask provenance signals. The Putumayo Basin is a broken foreland basin in western Amazonia at ~1°–3° N, where the Florencia, Macarena, and El Melón-Vaupes basement highs have compartmentalised discrete depocentres during basin development. This study presents new evidence from stratigraphic, conglomerate clast count, sandstone petrography, detrital zircon U–Pb geochronology and novel apatite detrital U–Pb age trace element geochemistry analyses. The results show that the southern Eastern Cordillera (i.e., Garzon Massif) and Putumayo Basin basement highs were initially uplifted during the Late Cretaceous coeval with the Central Cordillera, most likely associated with the collision of the Caribbean Large Igneous Province (CLIP). Distinctive facies distributions and provenance changes characterise the Putumayo Basin over a ~300 km distance from south to north, in the Rumiyaco Formation and Neme Sandstone. Detrital zircon U–Pb ages record a sharp reversal from easterly derived Proterozoic to westerly sourced late Mesozoic–Cenozoic Andean zircons derived principally from the Central Cordillera. Provenance signatures of the synorogenic Eocene Pepino Formation demonstrate the continued exhumation of the Eastern Cordillera as a second-order source area. However, the emergence of the northern intraplate highs modulated the provenance signature due to the rapid unroofing of relatively thinner marine sedimentary cover strata that overlie the Putumayo basement, in comparison to the thicker sequences of the southern basin. The provenance data and facies distributions of the Oligocene–Miocene Orito Group were more heterogeneous due to strike-slip deformation, associated with major plate tectonic reorganisation as the Nazca Plate subducted under the South American margin.

Estimations of source-to-sink sediment fluxes over geological timescales allow a better understanding of landscape sensitivity to forcings such as climate or tectonics. The Pyrenees Mountains represent an ideal location to test the accuracy of source-to-sink predictive methods, as the well-studied mountainous sources and sediment sinks, including the Aquitaine, Jaca, and Ebro basins, collectively serve as a reference for evaluating the accuracy of predictive approaches. This study uses a paleo-digital elevation model (pDEM) of Bartonian age (ca. 40 Ma) to reconstruct catchments for the Pyrenees. When coupled with published paleoclimatic constraints, the BQART equation is used to predict sediment fluxes into each sedimentary basin. Predicted sediment volumes are compared against volumes calculated from bedrock exhumation rates across the Pyrenees, and against published rock volumes preserved within Pyrenean sedimentary basins. Consistency between total sediment volumes predicted by the BQART model and for exhumation rates is within a factor of 1.5, and within a factor of 2 when sediment volumes are partitioned by sedimentary basin, indicating the pDEM is able to generate realistic, first-order estimates of sediment flux. An uncertainty analysis showed that the runoff category contributes the greatest uncertainty to the BQART equation, highlighting the requirement for paleoclimate and drainage constraints on this parameter. When BQART and exhumation-derived volumes are compared against preserved sediment volumes in the Aquitaine and Jaca Basins, sediments are undercounted by an order of magnitude. This is a result of the limited scope of volume quantification, as depocentres are defined by modern geography only, and from the postdepositional erosion of sediment in an active orogenic setting. Sediment volumes in the better-preserved Ebro Basin were predicted within a factor of 1.35 and 2.5. The results show that the pDEM-BQART method can appraise both the completeness of the sedimentary record within depocentres and successfully elucidate source-to-sink sediment routing within ancient orogens.

We present a structural and depositional interpretation in the southeasternmost Sorgenfrei–Tornquist Zone (STZ), one of the most prominent Late Cretaceous compressional inversion structures in Northern Europe. Detailed stratigraphic analysis of seismic facies and well data shows that the spatial and temporal variability of gravitational deposits, contourite drifts, and moats in the marginal troughs are related to the polyphase inversion tectonic history and the associated palaeoceanographic changes. The Hanö Bay and Bornholm Basin contain a sand-rich mounded depositional feature proximal to the STZ. This unit is resolved with high vertical resolution in seismic data and represents a clear example of a siliciclastic-carbonate mixed depositional system, where deposition was controlled by the interplay between inversion events and eustatic sea-level changes. Following the progradational and aggradational deposition during an early inversion phase and tectonic quiescence, a notable back-stepping pattern is observed in the upper Santonian–lower Campanian. The increased accommodation space outpaced sediment infill during eustatic sea-level rise in the late Santonian. We interpret that the marginal trough subsided during multiple inversion pulses associated with elastic flexure in response to inversion tectonics. The comparison of sequence-stratigraphic indicators and the global (eustatic) sea-level curve allows for a refined reconstruction of the inversion history and points to a major uplift in the Santonian–Campanian. Further, we attribute a penecontemporaneous change in the depositional pattern, i.e., the erosional Campanian–Maastrichtian contourite moat system, to intensified bottom current activity related to significant global cooling, in conjunction with the palaeoceanographic modification induced by the inversion tectonics described in this study.

Volcanic reservoirs represent an important target for CO₂ storage and large-scale deployment. We accessed the volcanic stratigraphy of the Paraná-Etendeka Large Igneous Province (PELIP) in South America through the analysis of petrophysical data from 9 exploration wells and regional seismic data. This approach enables the development of a refined geological model of the subsurface, offering new insights into facies distribution and reservoir characteristics. Stratigraphically, the PELIP consists of two major volcanic sequences: an older low-Ti (LT) sequence in the southern region and a younger high-Ti (HT) sequence in the central-northern area. Seven distinct lava formations have been identified based on their architecture and geochemical signatures, with the Vale do Sol, Pitanga and Paranapanema formations accounting for over 80% of the stratigraphy. The province is formed by thick (c. 25 m) tabular lavas with well-developed vesicular and brecciated upper crusts and subordinately compound lavas and volcaniclastic/siliciclastic deposits. Petrophysical analyses reveal a strong correlation between rock facies and reservoir properties (i.e., porosity and permeability). Lava flow tops exhibit high porosities comprising c. 10%–40% of the total flow thickness and represent viable targets for CO₂ injection. In contrast, massive flow cores are low in porosity and may act as effective seals. The PELIP is geologically similar to other large igneous provinces currently hosting CCS (carbon capture and storage) projects (Carbfix, Iceland and Wallula, USA). The large volume of basaltic rocks, along with high porosity facies and reactive compositions, makes the Paraná-Etendeka LIP a potential target for CCS developments in South America.

Wing-like intrusions are some of the most prominent architectural elements identified within subsurface sand injectite complexes. These structures are composed of discordant inner wing zones and bedding-concordant outer wing zones, which can crosscut hundreds of metres of stratigraphy and extend laterally for several kilometres. Their large-scale geometry makes them discernible on seismic data; however, the inability to detect associated smaller intrusions can lead to underestimates of their significance within a basin. To support subsurface analysis, this study integrates field and digital mapping analyses of two wing complex outcrops from two giant injection complexes of the San Joaquin Basin. The Dosados Canyon wing, of the Panoche Giant Injection Complex (PGIC), features a single 14 m thick stepped inner intrusion that bifurcates into outer sills. The wing extends laterally over 1.5 km, crosscutting ca. 300 m of mudstones. Up to 64% of the sandstones are associated with sub-seismic intrusions (< 3 m thickness). The Tumey Hill wing within the Tumey Giant Injection Complex (TGIC) intrudes vertically > 200 m of mudstones and extends laterally for at least 1.3 km. It comprises laterally stacked inner intrusions (up to 12 m thick) transitioning to a highly connected outer sill zone. A total of 225 intrusions (0.15 m to 8 m thick) are identified within the composite wing structure, adding sand volume and providing excellent connectivity. Comparison with the Volund and Varadero fields within the North Sea reveals intrusions with similar scale and geometry, underscoring the value of the outcrops as analogues for characterisation of subsurface reservoirs and to aid the understanding of sand intrusion formation within different basin settings.

Enigmatic N120° ridges have been identified from 3D seismic reflection imaging of the Bajocian limestones of the eastern Paris Basin. These features may impact flows within the active Middle Jurassic aquifer beneath the Callovian–Oxfordian claystones and marls that host the Underground Research Laboratory (URL) where the Andra (French National Agency for Radioactive Waste Management) is studying the feasibility of a deep repository for radioactive waste. Worldwide, there are numerous other examples where carbonate buildups form ridges in 3D, which are more or less interconnected, laterally amalgamated, or bifurcating, with no clear reason for these geometric features. It is consequently of paramount importance to understand the nature and origin of these ridges, and an integrated study combining (1) well logs, (2) new 3D seismic acquisitions, (3) classical field sedimentology and stratigraphy, (4) near-surface geophysics including ground penetrating radar (GPR), electrical resistivity tomography (ERT) and frequency-domain electromagnetics (FDEM) and (5) seismic refraction has been developed to investigate them. Facies analysis and a regional sequence stratigraphy interpretation, integrating near-surface geophysical imaging performed on time-equivalent outcrop sections, demonstrate that elongated mounds of hermatypic scleractinian corals developed during the early Bajocian (Humphriesianum chronozone) in shallow, warm oligotrophic seawater. These buildups nucleated as patches on hardground atop giant subaqueous dunes composed of peloidal and bioclastic grainstones, dipping mostly N30° with N120°-oriented crests. Some of the coral reefs form buildups up to 15 m high and several hundred meters wide. They are elongated in the main N120° direction of the underlying dunes, although the dispersion of measurements illustrates the complexity of the interfingered structures observed in 3D seismic images. The coral buildups are progressively onlapped and draped by oncoid-rich alternating marl-limestones that may result from a shift from oligotrophic to mesotrophic conditions probably brought about by a rise in relative sea level. Near-surface geophysics provide insightful supporting evidence to supplement the field work, particularly by imaging the roots of several coral reefs, their internal structures and the infill of the inter-reefal troughs. This work demonstrates the critical importance of outcrop analogue studies for resolving subsurface problems and also shows how near-surface geophysical methods can usefully supplement direct classical field geology investigations. This new characterisation suggests that coral reefs forming ridges, structures that have often remained enigmatic, could develop by directly settling at the top of early cemented giant oo-bioclastic dunes. Submarine early diagenesis generates hardgrounds that constitute stable substrates for nucleation and growth of coral reefs, especially when they cap prominent submarine relie