Basin Research最新文献

Middle to Upper Devonian strata preserved in the Mackenzie Mountains and adjacent basins in the Northwest Territories, Canada, record a transgressive sequence set of shelfal marine deposits in a low latitude basin margin transitioning from drift to convergence basin phase. The interplay between shallow-water carbonate and clastic depositional systems and offshore organic-matter-rich mudstone deposits is described within a chronostratigraphic and sequence stratigraphic framework. Relative rise of sealevel resulted in backstepping and flooding of a carbonate ramp by biosiliceous and organic-matter-rich mudstones. Steep isolated stromatoporoid carbonate platforms show rapid lateral facies transitions associated with these transgressions. At times of tectonically induced relative falls in sea level and exposure of updip carbonate deposits, clastic sediment was transported across the basin margin, resulting in the deposition of mud-rich subaqueous clinothems. Transgression of these clinothems led to the deposition of onlapping wedges of organic-matter-rich mudstones. Three main sequences are developed within this overall transgressive sequence set, and these three sequences can be correlated from outcrop to subsurface, both in the adjacent Peel and Mackenzie Valley Basins as well as into the subsurface strata of the Horn River and Liard Basins, which are prolific hydrocarbon basins to the south. Each depositional system develops distinct seismic geomorphologies and allows for the mapping of favourable lithofacies belts with regard to identifying carbonate deposits (aquifers and petroleum reservoirs) and organic-matter-rich mudstones (source rocks and unconventional reservoirs). The workflows and regional chronostratigraphic framework may be applied to coeval deposits along the divergent and convergent margins of Laurentian and Gondwanan cratons preserved across the globe.

The southern Levant Basin, Eastern Mediterranean, has a complex geological history. The separation of Africa from Arabia, and the collision of the latter with Eurasia during the Oligocene–Miocene had significant implications for the tectono-stratigraphy of the region, as recorded in the thick, siliciclastic-dominated sequence preserved in the southern Levant Basin. Previous studies mostly focused on either onshore or relatively local offshore areas, with a synthesis of the interplay between plate motions and sedimentation still lacking. Using multiple high-resolution, 3D seismic reflection surveys, we generated sediment thickness maps, spectral decomposition, and ISO-proportional slices that document the structural and sedimentological elements shaping the basin during the Oligocene–Miocene. More specifically, our results show that during the Early Oligocene, sedimentation was dominated by an easterly (Arabian) source, whereas the Late Oligocene to Aquitanian witnessed a shift to a southerly (African) source through the evolution of the Nile River. The Burdigalian period marked a significant tectono-stratigraphic transition period during which large-scale folding, regional faulting and renewed incision had occurred. The Langhian–Serravallian was followed by widespread carbonate deposition. The Early Tortonian is marked by a thick, extensive, seismically chaotic interval that underlies deposits associated with the Messinian Salinity Crisis. This interval is identified across the basin, being associated with the collision of Cyprus and Eratosthenes, a major tectonic event that affected the entire Southern Levant Basin. The Late Tortonian–Messinian was largely characterised by widespread submarine incision across the southern Levant Basin. Our study reveals how sedimentary systems record important clues as to complex tectonic reorganisations involving rifting, subduction and strike-slip motion.

Mississippian-aged (Lower Carboniferous) syn-rift carbonate platforms in the UK have been extensively studied in outcrop. They have been interpreted to grow principally on the footwall of faults, with deeper marine sedimentation in the adjacent hanging wall basins. However, the transition from the shelf margin to the basin is often poorly constrained due to a lack of exposure and the scarcity of high-quality seismic data. With renewed interest in Mississippian carbonate strata as potential geothermal reservoirs in northern Europe, a better understanding of the detailed geometry of these carbonate platforms, and the controls on their growth and demise, is crucial as it provides insights into their occurrence, size and thickness and burial/exposure history. This study uses high-resolution 3D seismic data from the southern part of the offshore East Irish Sea Basin (EISB), western UK, to identify, characterise and map the platform to basin transition of the North Wales carbonate platform, exposed on the North Wales coastline. The results indicate that there is not a simple platform to basin transition, as has previously been mapped, but that the North Wales platform gives way offshore to numerous small carbonate platforms, the presence of which is predominantly controlled by N-S-oriented extensional faults. The fault orientation is not consistent with the regionally interpreted N-S stress direction during the Mississippian, but fault growth analysis suggests that their orientation most likely reflects the precursor structural grain. These faults facilitated the development of horst-graben structures, promoting carbonate growth on footwalls within the EISB. Six areas of potential carbonate platform development (A1–A6) were mapped and evaluated. Thicknesses range from ~1 to 2 km. The platforms prograded during the Tournaisian, characterised by low-angle slopes, followed by a backstepping phase in the Visean, marked by steeper slopes. The platforms significantly shrank in size from the early Tournaisian to the Visean, resulting in the formation of complex, patchy carbonate platforms with diverse shapes and sizes. The results demonstrate that numerous small carbonate platforms grew in the EISB on structural highs but were susceptible to environmental change at the end of the Mississippian, causing them to become increasingly isolated and to eventually drown.

Megabeds, also known as ‘megaturbidites,’ are exceptionally large submarine sediment deposits likely formed by catastrophic geohazard events. These deposits are increasingly being identified with modern high-resolution geophysical data, yet their origins and characteristics remain debated. Five megabeds have been identified in the Marsili Basin of the Tyrrhenian Sea within the upper 70 m of sediment. These deposits are hypothesized to have been triggered by explosive volcanic eruptions of the Campanian Volcanic Province, including the ~39.8 ka Campanian Ignimbrite (CI) super-eruption, which is among the largest known eruptions, having a volcanic explosivity index (VEI) of 7. These megabeds were intersected by Ocean Drilling Program (ODP) Leg 107 Site 650, where sediment cores were collected in 1986. However, their presence was not recognized at the time due to lack of appropriate geophysical data. To better understand the properties and origins of the Marsili Megabeds, we identified the megabeds within the ODP cores and conducted detailed sedimentological and elemental analyses, along with age dating, to determine their possible sediment provenance, depositional mechanisms, and potential triggering events. Elemental analysis and age dating suggest a potential link between these megabeds and known eruptions from the Campanian Volcanic Province, including the Neapolitan Yellow Tuffs eruption (14.9 ka), the Masseria del Monte Tuff eruption (29.3 ka), and the Campanian Ignimbrite super-eruption (39.8 ka). A new megabed discovered below the Y-7 tephra is older than 60,300 years but its triggering event is unknown. The re-examination of ODP cores reveals that not all megabeds conform to a megaturbidite morphology. In the Marsili Basin, the variety of sedimentological structures differs within and between megabeds, suggesting varying and complex depositional mechanisms. The findings reveal that the megabeds are more internally complex than previously thought, with variations in their depositional processes even in one basin.

The geometry and evolution of the rivers originating from the Tibetan Plateau have been influenced by topography and climate changes during the India–Asia collision. One notable example is the Jinsha (upper Yangtze) River, which expanded its drainage area at the expense of other rivers through several river captures, the timing of which remains controversial. This study focuses on the Yalong River, a major tributary of the Jinsha River, characterised by deep gorges, sharp elbows, where the river exhibits abrupt changes in channel orientation, and interfluves with high-elevation, low-relief areas that contain riverine sediments. One such area north of the Yalong–Jinsha confluence is the Yanyuan Basin, which is filled with mainly Eocene alluvial fan deposits and Pliocene fluvial conglomerates that preserve part of the detrital history of the Yalong River. We use detrital rutile U–Pb, muscovite ⁴⁰Ar/³⁹Ar, zircon U–Pb, and fission-track double dating to constrain the provenance of the Cenozoic detritus of the Yanyuan Basin. Our combined data suggest that the Eocene clastic infill of the Yanyuan Basin was mainly supplied by the Paleo-Yalong River, which, like the modern Yalong, originated from the Yidun Arc but flowed southward into the Yanyuan Basin, in contrast to the river's current course that flows around the basin and then southward. In the Pliocene, the presence of a small population of young (Cenozoic) zircon grains alongside a dominant population of Neoproterozoic zircons, rutiles, and muscovites shows that the Paleo-Yalong catchment expanded eastward, including a river originating from the Gongga batholith that flowed southwestward into the Yanyuan Basin. The absence of Cenozoic and Late Cretaceous detrital ages in the modern Yalong River, alongside the presence of the Late Cretaceous ages in the modern Jinsha River, indicates that between the Pliocene and the Present, the Yalong basin experienced a reduction in area on both its western and eastern margins. Finally, during this time, drainage reorganisation resulted in the isolation of the Yanyuan Basin from distant sediment sources, as the Yalong entrenched into its modern gorge.