Basin Research最新文献

The Cretaceous lower Nanaimo Group in the Georgia Basin, Canada comprises multiple depositional phases with distinct depocentres that accumulated in a tectonically active forearc basin setting. Basal coarse-clastic strata are preserved in paleotopographic depressions and grade upwards into coal-bearing coastal plains and shallow-marine deposits. Coal-bearing and shallow-marine strata grade laterally into and are overlain by, regionally extensive mudstones and turbidites deposited in deep water. A glauconitic sandstone bed within the deep-water strata is interpreted as a condensed section and underlies a major disconformity that developed during a pause in the deposition of the lower Nanaimo Group. A second major coarse-clastic succession occurs hundreds of metres above the glauconite bed in the central Georgia Basin and comprises conglomerate, sandstone, mudstone and coal deposited in continental depositional environments. The shift in sedimentation from the northern Georgia Basin to the central Georgia Basin is interpreted to record the emergence of an island (Nanoose Uplift) in the central Georgia Basin that acted as a major sediment source to the adjacent depocentres. The stratigraphic break between the coal-bearing coarse-clastic strata in the northern Georgia Basin and the significantly younger coal-bearing coarse-clastic strata in the central Georgia Basin indicates that the lower Nanaimo Group was deposited in distinct depocentres. Between the older, coarse-clastic strata in the north and younger, coarse-clastic strata in the central Georgia Basin, we hypothesize that a major deepwater canyon system (Qualicum Canyon) existed and transferred sediment from the semi-restricted Georgia Basin to the Pacific Ocean to the west. Development of the Qualicum Canyon and exposure of the Nanoose Uplift during deposition of the younger, central coarse-clastic strata suggests that syntectonic activity drove basin uplift and erosion and this occurred throughout the deposition of the lower Nanaimo Group.

The submarine fan with a narrow shelf is usually reactive to environmental signal propagation; however, source-to-sink functioning can be further complicated by several allogenic forcings. Here, we document the high-frequency provenance variations and different sediment delivery models recorded in the late Triassic Zhuoni fan developed in the northeastern Paleo-Tethys Ocean, mainly based on process-based sedimentological and provenance study of the Panyuan section in the West Qinling area in the northeastern margin of Tibetan Plateau. High-, low-density turbidites, hybrid event beds and hyperpycnites are distributed in the lobe-dominated submarine fan succession. Field sedimentological evidence from surrounding outcrops suggests that shelf-edge failure was the main cause of most high- and low-density turbidites with the overall absence of submarine slides or slumps, whereas the narrow shelf configuration together with late Triassic humid pulses is favourable for the occurrence of flood-related hyperpycnites in the Zhuoni fan. Detrital zircon grains (N = 6; n = 123–272) generally have Palaeozoic-Mesozoic ages (ca. 350–250 Ma and 500–400 Ma) and Neoarchean-Paleoproterozoic ages (ca. 2100–1750 Ma and 2600–2400 Ma), but they can be further categized into three age groups due to different proportions of Precambrian age populations. The results demonstrate that the potential source areas may include the South and North Qinling Orogenic Belt, Qilian Orogenic Belt, different segments of North China Craton and the tectonic junction area between the Qinling and Qilian Orogenic Belts. The temporal changes in provenance signals, which are reflected by both the detrital zircon age spectra and heavy mineral assemblages, indicate different contributions of those sources in response to sea-level fluctuation. It could thus give rise to temporal variations between reactive and buffered source-to-sink sediment delivery models of the Zhuoni fan, despite the overall narrow shelf configuration. The development of the lowstand Zhuoni fan was directly related to extrabasinal hyperpycnal delivery from the river mouth and its high-frequency provenance variability recorded different efficiencies of signal transfer through the onshore catchment with significantly influence of temporal storage, fluvial rejuvenation or even regional climate variability. The highstand submarine fan was thought to be formed by shelf-edge failure with sediment buffering in the shelf region, which was associated with a strong magnitude of provenance mixing. Our work provides a new perspective for deciphering the different origins of deep-water sediment delivery in response to high-frequency sea-level and climate changes.

Thin, condensed coarse-grained shallow marine successions can be difficult to describe and interpret, especially in the subsurface since the recognition of finer-grained intervals, typically associated with sequence stratigraphic surfaces, is challenging. This lack of mudstones and siltstones means that they also typically make excellent reservoir intervals. The Oxfordian to Volgian intra-Draupne Formation sandstones in the Johan Sverdrup Field, southern Utsira High, represent such a system. This study presents a new sequence stratigraphic model for the Johan Sverdrup Field that unravels the detailed depositional history of the succession and places its formation within a regional Late Jurassic tectonostratigraphic framework. The intra-Draupne Formation sandstones comprise four parasequences deposited following a regional Kimmeridgian marine flooding event. Sediments were mainly supplied through West-derived fan deltas from the Haugaland High and NW-SE-directed tidal currents reworking the Augvald Graben and the Avaldsnes High at the East. The oldest parasequence shows a distinctive suite of facies consisting of fine-grained and mud-rich bioturbated sandstones deposited in a semi-restricted lagoon. Subsequent parasequences lack fine-grained sediments and are dominated by bidirectional cross-stratified, very coarse-to coarse-grained sandstones and gravels deposited in a tidal strait. A progressive reduction of fault-related subsidence in the Middle Volgian along with Late Volgian-Ryazanian sea-level rise and inversion of pre-existing structures promoted backstepping of the feeder systems, sediment starvation and the progressive deposition of the black and green-red shales of the Draupne and Asgard formations. The results of this study account for features previously unidentified in the Johan Sverdrup Field and which have implications for understanding the deposition of coarse-grained shallow marine successions around the Utsira High and other transgressed basement highs.

The isolation of the eustatic signal from the sedimentary record is a challenging task, and accordingly, there is no consensus on the magnitude and pace (rate) of eustatic events in the geological record. Here we critically assess various published short-term Cretaceous eustatic curves using insights from forward stratigraphic modelling. We generate a range of simulations with varying eustatic rates and sediment supply against a background of constant subsidence. From these, we generate statistics on the accommodation change associated with the various systems tracts for different sediment supply. We quantify the minimum rate needed to generate transgressive systems tracts (TST). Using this threshold and average subsidence rates for passive margins and intracratonic basins, we document some key challenges with a range of Cretaceous eustatic curves. While it is possible to complexify, this approach through the inclusion of other parameters, our results provide a framework for evaluating eustatic (or relative sea level) curves in terms of the implied rate of change of accommodation. Given these caveats, we also show that many estimates of the magnitude of short-term transgressions are of insufficient rate to generate observable TST. Further, our work places an upper limit on the time frame over which aquifer and thermo-eustasy can have observable impacts on the rock record, providing support for the action of glacio-eustasy during the Cretaceous.

Foreland basins are ideal laboratories to examine and quantify forces that contribute to Earth's topography. The interaction of these driving mechanisms (atmospheric, lithospheric and asthenospheric) affects the accumulation and preservation of strata in marine or terrestrial depocentres. For foreland basins that cover thousands of kilometres along orogens, geodynamic processes or lithospheric structure might differ and/or overlap differently along or across strike. The Magallanes-Austral basin in the southernmost Patagonia serves as a good analogue to analyse the interactions between subcrustal forces and foreland sedimentation. While to the northern part of southern Patagonia, Cenozoic basins were predominantly terrigenous and above sea level; at the southernmost end of Patagonia, sedimentation in the island of Tierra del Fuego was mostly submarine. We analysed in this contribution the southernmost foreland of Patagonia by combining backstripping with reconstruction of flexural and dynamic subsidence. These results were compared with terrestrial records exposed further north of southern Patagonia. We found that, in addition to crustal contributions (as deformation and sedimentation), subcrustal forces are required to accommodate the proximal and distal foreland strata and explain the palaeoenvironmental and subsidence discrepancies that resulted after our analysis. When our models are compared with dynamic topographic curves, strong correlations are observed during the Palaeogene, whereas strong topographic differences occurred in the Neogene. Dynamic topography models in the Neogene have reproduced clear uplift, whereas our residual topography results show equilibrium (close to the orogen) to subsidence values (to the distal foreland). We propose that changes in the lithospheric mantle had to work together with the rest of the tectonics and dynamic forces to match 1-D backstripping and flexural curves. This suggests that foreland basins in southern Patagonia were controlled differently along strike the southern Andes and that crustal deformation, asthenospheric flows and a heterogeneous lithospheric mantle structure affected the Cenozoic basin evolution.

Source-to-sink sedimentary systems associated with volcanic rifted margins serve as important archives for basin development by recording lithospheric changes affecting the depositional systems. Distinguishing between sediment transport processes and their sediment source(s) can guide the interpretation of a basin's history, and thereby inform regional paleogeographic reconstructions. In this contribution, we integrate and utilize wireline geophysical logs, detailed petrographic observations from side-wall cores, and seismic analysis to describe and decipher a Maastrichtian to Danian-aged basin-floor depositional system in the deep outer Møre Basin, mid-Norwegian margin. Well 6302/6-1 (Tulipan) is a spatially isolated borehole drilled in 2001 that penetrates Maastrichtian and younger strata. A succession of hitherto undescribed carbonates and sandstones in the outer Møre Basin was discovered. It is investigated for sediment transport, provenance, and depositional processes on the basin floor surrounded by structural highs and ridges. The strata from the lower parts form a basin-floor apron consisting of redeposited carbonate sourced from a westerly sub-aerial high. The apron transitions vertically from mixed siliciclastic and carbonate into a purely siliciclastic fan with intercalated sandstone and mudstone, providing a rare high-resolution record of how depositional environments experience a complete shift in dominant processes. The development coincides with similar latest Cretaceous-earliest Palaeocene sequences recorded south of this region (e.g., well 219/20-1) and may have been influenced by regional uplift associated with the onset of magmatism in the Northeast Atlantic. This study improves our understanding of a late, pre-breakup source-to-sink sedimentary system developed near the breakup axis of an infant ocean, and documents what is possibly the northernmost chalk deposit in the Chalk Group.

The influence of bottom currents on submarine channels has been widely recognized, for instance, by the formation of asymmetric channel-levee systems and drifts. In contrast, it is often considered that submarine lobes can be only reworked by strong bottom currents and are not affected by bottom currents during their deposition. In this study, we analyse the potential effect of bottom currents on different hierarchical lobe architectures that formed during the lower Oligocene in the Rovuma Basin offshore East Africa. We characterize the stacking patterns, morphology and connectivity of different hierarchy lobes using well data and three-dimensional seismic data. We found no direct influence of bottom currents on the lobe complexes and single lobes that show a unidirectional stacking pattern that is opposite to the direction of bottom currents. Lobe elements in single lobes display vertical accretion with no obvious relationship with bottom currents. Additionally, the first deposited single lobe morphology presents an asymmetric shape, with a thicker lobe margin on the downstream side of the bottom currents, but this is due to an initial low topography on the downstream side rather than bottom currents. The architectural distribution reflects that the topography present before the depositions of the submarine lobes was controlled by previous asymmetrical channel-levee systems formed by the synchronous interaction of bottom currents and gravity flows. This asymmetric topography controls the subsequent deposition of lobes and results in the migration of single lobes in the upstream direction of bottom currents. Although weak to moderate bottom currents may not be able to substantially rework submarine lobes, our results demonstrate that they may control the geometry and evolution of submarine channels and thus indirectly affect the thickness and migration of lobes in more environments than previously thought.

The Tibetan Plateau uplift has significantly influenced Asian geomorphic and climate patterns. Drainage evolution across the plateau and its surroundings as the consequence of such changes in landscape and climate provides an opportunity to understand the growth of the Tibetan Plateau. However, the evolution history of major drainage areas around the Tibetan Plateau is largely unknown. Here, we reconstructed the evolution of drainage patterns of the Cenozoic Longzhong Basin in the northeastern Tibetan Plateau since the India–Asia collision using palaeo-water solute ⁸⁷Sr/⁸⁶Sr ratio records from its subbasins. Higher solute ⁸⁷Sr/⁸⁶Sr ratios of the Lanzhou and Xining Basins and their consistent temporal variations before ca. 22 Ma as well as lower solute ⁸⁷Sr/⁸⁶Sr ratios in the Linxia Basin collectively indicate a relatively steady drainage pattern of the integrated Longzhong Basin. A diverse evolution of the solute ⁸⁷Sr/⁸⁶Sr ratio in the Lanzhou and Xining Basins after ca. 22 Ma suggests that there was a drainage reorganization, characterized by the division of one into multiple catchment centres, in response to the growth of the northeastern Tibetan Plateau. Subsequently, the identical solute ⁸⁷Sr/⁸⁶Sr ratios in the Lanzhou and Xining Basins were further approached at ca. 16 Ma, and the rise in the solute ⁸⁷Sr/⁸⁶Sr ratios of the Linxia and Tianshui Basins occurred at ca. 9–8 Ma, indicating two subsequent changes in solute composition induced by the middle Miocene uplift and late Miocene dust expansion, respectively. Our reconstructions of Cenozoic hydrological evolution in the Longzhong Basin indicate accelerated basin segmentation and drainage adjustment with solute change in response to the growth of the northeastern Tibetan Plateau during the Neogene.

Clarifying the role of mountain-building processes in the filling history of large hinterland basins is an essential aspect of basin–mountain system research. We consider the case of the Triassic South Ordos Basin (SOB) to clarify these points. Located in the south-western North China Block (NCB), the SOB which preserves the most complete Triassic deposition on the north of the Qinling Orogenic Belt (QB) is crucial for understanding the detailed tectonic processes of the QB. Sedimentological, petrological and zircon U–Pb geochronological signatures from the three parts (eastern, central and western) in the SOB indicate that the sediment source migrated both temporally and spatially. Stratigraphic correlation identified two fluvial progradational episodes from south to north in the fluvial–deltaic–lacustrine sedimentary system, one in the eastern SOB and the other in the central SOB. The Late Triassic detrital zircons in the central SOB with distinguishing Neoproterozoic ages were derived from the southern margin of the NCB and the QB. The western SOB exhibited the sediment source shifted from pre-Triassic North Qilian Belt sedimentary cover to basement from the Middle-to-Late Triassic based on a zircon age transition from ca. 2000 to ca. 430 Ma. Late Triassic sediment sources also included the southern margin of the NCB and the QB. Differing provenances from east to west were also confirmed using thin section and heavy mineral analyses. Regional comparisons of zircon age distributions in the eastern SOB with published data indicate that detritus from the QB was first transported to the eastern SOB and then to the central and western SOB. Spatiotemporal changes in the sediment source and sedimentary filling transitions in the three parts of the SOB suggest that the QB underwent asynchronous uplift that began in the east during the Early Triassic and propagated westward, reaching its maximum extent in the early Late Triassic.

Basin-scale outcrop analyses of fluvial architecture in the Palaeogene San Juan Basin, New Mexico, document lateral and vertical trends in channel, floodplain and palaeosol characteristics. Herein, the uppermost part of the Palaeocene Nacimiento Formation and lower Eocene Cuba Mesa and Regina Members of the San Jose Formation are identified as deposits of large fluvial fans based on trends observed across the basin. Stratigraphic trends suggest two packages originated by fluvial fan progradation. Progradation of the lower fan system provides a new explanation for the transitional nature of a disconformity at the Nacimiento–San Jose Formation contact, previously thought to be a low-angle unconformity. The two fan systems are separated by a retrogradational interval that culminates in a depositional hiatus at the contact between the Cuba Mesa and Regina Members. This, combined with poor age constraints, indicates that the duration of the disconformity at the base of the Cuba Mesa Member may have been overestimated. Furthermore, the succession is interpreted as deposits of variable-discharge rivers, based on the combined abundance of upper flow regime and high deposition rate sedimentary structures indicative of intense flooding events, preservation of in-channel bioturbation and paedogenic modification indicating periods of prolonged dryness, lack of identifiable bar strata and alternations of poorly drained and well-drained floodplain deposits with pedofacies indicating alternating wet–dry cycles. This dataset adds to a growing body of evidence linking the formation of large fluvial fans to discharge variability and thus to hydroclimates with significant inter- and intra-annual precipitation variability and intense rainfall. A long-term stratigraphic shift from poorly drained to well-drained floodplain deposits across two progradational fan successions indicates that a predictive model suggesting downstream decreases in soil drainage conditions is not encompassing of all large fan systems, and instead suggests a transition to a more arid climate across the Palaeocene–Eocene boundary.