Basin Research最新文献

Subduction trenches receive sediment from sediment gravity flows sourced from transverse pathways and trench parallel axial transport pathways. Understanding the interplay between axial and transverse sediment transport in shaping stratigraphic architectures is hindered by the episodic nature of sedimentary gravity flows and limited datasets, yet such insights are crucial for reconstructing sedimentary flow pathways and interpreting sedimentary records. We investigate sediment routing pathways to the northern Hikurangi Trough of New Zealand using a combination of multibeam, 2D and 3D seismic reflection and International Ocean Discovery Program core data from Site U1520. Site U1520's location downstream of axial and transverse conduits of sediment delivery makes it an excellent location to observe how these processes interact in deep marine settings. We characterise regional basin floor geomorphology and sub-surface architecture of the upper ~110 m siliciclastic sequence of the Hikurangi Trough deposited over the past ~42 ka (Seismic Unit 1; SU1). Sediment delivery to the trough is fed by sediment gravity flows sourced from both the shelf-incising transverse Māhia Canyon to the south-west and the axial Hikurangi Channel to the south. Flows sourced from these systems have a strong influence on the geomorphology of the region and are responsible for forming large-scale bathymetric features such as erosional scours and sediment waves. Sedimentary features identified within SU1 indicate that sediment transport via the transverse Māhia Canyon was more significant than that of the axial Hikurangi Channel throughout the last 42 ka, particularly during the last glacial period when sea levels were lower, and sedimentation rates were extremely high (up to ~20 m/kyr). This study emphasises the need for a nuanced consideration of transverse and axial systems and how they may influence sediment records and the geomorphic characteristics of trench systems.

Downstream changes of fluvial styles and related grain size triggered by localised tectonically-induced changes in riverbed gradient are still poorly understood, especially in terms of their impact on the accumulation of alluvial successions. In this study, we analyse the morpho-sedimentary response of rivers crossing multiple fault-controlled subsiding areas, by using field data from the age-constrained, fluvial deposits of the Pleistocene Dandiero Basin (Eritrea) to create scaled, controlled laboratory experiments performed at the Eurotank Stratigraphic Analogue Modelling Facility (Utrecht University, NL). With this experimental series, we quantified the impacts of degradational/aggradational fluvial dynamics showing that stream bed degradation occurs upstream of subsiding depocenters following the localised increase in river slope. Following a tectonic-induced decrease in river slope, aggradation occurs downstream of the fault zones, and marked in-channel aggradation promotes the branching of major river trunks into minor channels and the development of unchannelised tabular bodies. Experiments also show that highly subsiding areas promote the accumulation of fine-grained deposits, but their accumulation zones shift downstream following localised bed aggradation. We show that where multiple subsiding areas occur along a river, localised depocenters separated by degradational areas occur, causing general starvation in the downstream subsiding reaches, where lacustrine deposition became common. These findings suggest that the role of active faults could have been significantly overlooked when studying how changes in allogenic forcings impact alluvial strata. The results obtained in this study offer a solid basis for creating a predictive model for facies distribution in river dynamics, providing insights into detecting neotectonic signatures in active rivers and identifying tectonic imprints on ancient fluvial successions.

Flexure in pro-foreland basins results from the interplay between (sub)surface loading, foreland plate strength, inherited crustal architecture, and the degree of plate coupling. It is expected that lateral variations in these controlling mechanisms will result in along-strike variations in the flexural profile of the foreland basin. This will directly influence the position and width of the forebulge, thereby altering the associated extensional stress field in space and time around which syn-flexural normal faults accommodate deformation. As such, spatiotemporal variations in the growth of the syn-flexural normal faults in foreland basins may provide valuable information regarding the evolution of an orogen-foreland basin system. However, the relation between syn-flexural normal fault growth and the mechanisms controlling foreland basin flexure remains underexplored. Here, we quantify lateral and vertical throw distributions for growth strata of syn-flexural normal faults in the German Molasse Basin. This allowed us to develop a 4D fault growth model. Our results indicate that the flexure in the German Molasse was associated with both the nucleation of new faults and selective reactivation of pre-flexural faults, with the latter depending on fault burial depth at the onset of flexure. Furthermore, our results suggest that localisation of the extensional strain and deformation at the top of the European plate during flexure controlled the nucleation site of the syn-flexural normal faults in the German Molasse. Additionally, the spatiotemporal variation in the onset of syn-flexural normal fault activity suggests a northward migration rate of 7.8 mm/year of the orogen-foreland basin system. This is consistent with previous estimates based on other independent methods. Lastly, a west-to-east increase in cumulative syn-flexural offsets down-dip the normal faults in the German Molasse Basin may have been controlled by orogen-parallel lithospheric strength variations in the downgoing European plate.

Buried pockmarks are features associated with fluid seepage through ancient seafloors. In this work, high-quality 3D seismic reflection and well data are used to investigate the geometry, distribution and significance of listric faults and associated pockmarks in a salt minibasin from offshore Espírito Santo, SE Brazil. The results show that six out of ten pockmarks interpreted in the study area have crescent, elliptical, or elongated shapes. They occur along the trace of listric faults and on their immediate hanging-wall blocks, with pockmarks' long axes being nearly parallel to the strike of the faults. The pockmarks are approximately 1300–6200 m long, 600–4000 m wide, 30–139 m deep, and buried 50 to 500 m below the modern seafloor. They can be divided into fault-strike (type I) and fault hanging-wall (type II) pockmarks based on their spatial relationships. Type I represents pockmarks developed along the trace of listric faults, which acted as fluid conduits. Type II pockmarks were developed away from fault traces on their hanging-wall blocks. Their occurrence near listric faults was controlled by multiple factors, including the relative depth, length, area, and maximum displacement of listric faults. In addition, listric faults below horizon H4—an Upper Paleogene unconformity—do not show pockmarks around them. Listric faults with greater length, area, and maximum displacements were more likely to form pockmarks. In conclusion, the studied pockmarks are evidence for local hydrocarbon escape occurring in the Espírito Santo Basin since the Miocene. The results presented here can be applied to other regions around the world prone to geohazards and where carbon and hydrogen storage solutions are being proposed.

Orogenic wedges juxtapose tectonic units that originated far from each other, and tracing these back to their origin is often difficult. We have studied two contrasting serpentinite–sediment associations of the Alpine-Apennine orogenic wedge of eastern Elba Island with the help of a detrital zircon study of the sediments and a geochemical comparison of the relic phases of their associated serpentinites. We demonstrate that these very likely originated in different branches of the Ligurian Ocean and in contrasting tectonic settings, one during opening of Alpine Tethys and the other during Apenninic contraction-exhumation. First, the Early Cretaceous Palombini shales are associated with abyssal ocean floor serpentinite–ophicalcites of a Ligurian ophiolite (LO) that originated in the western branch of the Ligurian Ocean during ultraslow spreading. They have an Adria/African zircon provenance, indicating proximity to Adria rather than Corsica-Europe and the associated serpentinites are highly depleted and relatively little deformed. The second sediment–serpentinite association has a tectonised serpentinite band in contact with highly deformed, Miocene blueschist facies metasediments. Detrital zircons of these metasediments (Acquadolce (AD) and Pseudomacigno) record major Eocene–Oligocene U–Pb zircon age peaks, with an igneous provenance in the western and central Alps respectively. An age peak at ca. 38 Ma links the Pseudomacigno sediments to calc-alkaline volcanic rocks of the central Adamello massif, whilst an Oligocene age peak at ca. 32 Ma indicates western Alpine sources for the AD Unit. The associated massive, highly tectonised AD serpentinite represents most likely a mantle sliver of subcontinental lithospheric mantle, which together with Oligocene blueschist facies rocks underwent synorogenic Apenninic tectonic extrusion during W-directed subduction–rollback of the eastern branch of the Ligurian Ocean.

Stratigraphy and its associated grain size preserve a record of the dynamic behaviour of source-to-sink systems over time. Sediment supply and available accommodation space primarily control downstream grain-size fining preserved in stratigraphy. In principle, these grain-size trends can be inverted to quantify temporal and spatial variation in these driving forces. Here, we illustrate how grain size and stratigraphic thickness can be used to quantify fault growth and interaction using the early-mid Pleistocene Pirgaki-Mermoussia (P-M) fault, Gulf of Corinth, Greece, as a natural laboratory. A 2.5 km long exposed cliff section of the uplifted Kerinitis Gilbert-type delta, which lies in the hanging wall of the P-M fault, was selected for study. In the field, we traced out stratigraphic units in the lower part of the Kerintis delta, which are bounded by flooding surfaces, and measured their thickness to reconstruct hanging wall subsidence. We collected down-system grain-size data at 31 measurement sites using the Wolman point count method. Our results show the observed grain-size fining rate increase from 11 to 17 mm.km⁻¹ for the lower delta deposits over a timescale of up to 120 kyr. Using a self-similarity-based grain-size fining model and considering a minimum increase in accommodation generation from 0.6 to 1 mm year⁻¹ over this period, we reconstruct an increase in delta sediment supply from ca. 170 to 460 m³ year⁻¹. The integration of stratigraphic thickness measurements with grain-size fining trends enables quantitative reconstruction of temporal variations in fault-driven accommodation space and sediment supply, thereby demonstrating fault slip rate evolution. We show an increase in the P-M fault slip rate during its early history from 1 to 2 mm year⁻¹, reflecting early interaction of the P-M fault segments over ca. 120 kyr. Reconstructed catchment-averaged erosion rates are ca. 20% of the footwall uplift, implying a transient response of the landscape to the P-M fault growth. These analyses demonstrate how grain-size data from a well-constrained geological example can be used to reconstruct landscape dynamics quantitatively in fault-controlled sedimentary systems with high temporal and spatial resolution.

The Levant Basin of the Eastern Mediterranean accumulated voluminous siliciclastic sediments during the Oligocene–Miocene. The deep-sea section has attracted significant interest as it contains world-class hydrocarbon reservoirs (‘Tamar Sands Play’). Our recent sandstone provenance study revealed that the hydrocarbon-bearing, lower Miocene ‘Tamar Sands’ were recycled from older quartz-rich sandstones that covered the Arabian flank of the Red Sea Rift. However, sandstones constitute just a third of the thickness of the Oligocene–Miocene siliciclastic section in the Levant Basin, with the rest being mainly composed of shales. Unravelling the provenance of the shale fraction is therefore essential for a comprehensive reconstruction of the Oligocene–Miocene source-to-sink system of the Levant Basin. In the present study, we examined the mineralogy and Sr-Nd isotopes of clay samples retrieved from deep-sea boreholes that penetrated the Oligocene–Miocene siliciclastic section. The isotopic composition of most clay fractions resembles that of Nile Delta sediments, indicating that unlike the ‘Tamar Sands’, their dominant provenance lay in NE Africa. Our investigations show that they were derived from Neoproterozoic basement rocks of the Arabian-Nubian Shield and Tertiary continental flood basalts. The absence of chlorite and serpentine negates detrital contribution from the Arabia-Eurasia suture in the north. Compilation of the available thermochronology data and major geologic events shows that the accumulation of the siliciclastic section in the Levant Basin coalesced with uplift of the continental areas around the Red Sea. The marked switch to shale deposition recognised in the basin during the late early Miocene signifies the downfall of the ‘quartzose’ Arabian sediment transport system, when it was partially captured by the evolving Dead Sea Transform valley. Our study highlights the strength of coupling sand and clay provenance investigations in source-to-sink studies of sedimentary basins.

In this contribution, we document changes in detrital zircon ages in the upper Devonian (Famennian) to lower Carboniferous (Mississippian) Billefjorden Group on Bjørnøya, the southernmost island of Svalbard. This alluvial, coal-bearing clastic succession is widely distributed across the archipelago and the Barents Shelf. The sediments were deposited in subsidence-induced lowlands that formed just after regional post-Caledonian collapse-related extension, which created the classical ‘Old Red Sandstone’ basins during the Devonian, and prior to localised rift-basin development in the middle Carboniferous (Serpukhovian–Moscovian). Moreover, the succession is little affected by Ellesmerian compressional deformation, which occurred in the latest Devonian. However, little is known of the provenance and regional sediment routing in this tectonically transitional period between the post-Caledonian structuring events in the Devonian and the middle Carboniferous rifting. It has previously been invoked that a regional fault running parallel to the western Barents Shelf margin, the West Bjørnøya Fault, controlled sedimentation in the area. Here, we combine detrital zircon U–Pb ages and sedimentological data to investigate stratigraphic provenance variations and test whether tectonics controlled deposition of the Billefjorden Group on Bjørnøya. Sedimentological investigations demonstrate changes in fluvial style with intercalations between successions dominated by meandering channel fills and abundant overbank fines to sandstone-dominated sheet-like successions of braided stream origin. Palaeocurrent data show that two competing drainage directions accompany the changes in fluvial architecture. Northeasterly transport directions, recorded in the braided stream deposits, indicate possible fault-transverse drainage. The detrital zircon content in these deposits indicates sourcing from Caledonian terranes in Northeast Greenland. Northwest-oriented transport directions, measured in the meandering channel deposits, are inferred to represent axially positioned drainage systems. These may have been sourced from either Northeast Greenland, a more localised source, or Baltica. The latter would require long-distance sourcing, which, given the tectonic setting of the region, seems unlikely. Although our sedimentological observations point to syn-tectonic deposition, this is not clearly captured in the detrital zircon data, suggesting a common source for the Late Devonian–Mississippian fluvial systems of Bjørnøya. Thus, combined with previously published provenance data from Svalbard and Greenland, we demonstrate that the East Greenland Caledonides formed a long-lived and significant source area which provided sediments to nearby basins from the Devonian to the Early Cretaceous.