Basin Research最新文献

The syn-rift architecture of extensional basins records deposition from and interactions between footwall-, hangingwall-, and axially-derived systems. However, the exact controls on their relative contributions and the overall variable depositional architecture, and how their sediment volume varies through time, remains understudied. We undertook a quantitative approach to determine temporal and spatial changes in the contribution of fault-scarp degradation to the syn-rift tectono-stratigraphic development of the Thebe-0 fault system on the Exmouth Plateau (NW Shelf, offshore Australia), using high-quality 3D seismic reflection and boreholes data. The magnitude of footwall erosion was measured in terms of vertical (VE) and headward (HE) erosion by calculating the volume of eroded material along the footwall scarp. A detailed seismic-stratigraphic and facies analysis allowed us to constrain the architectural variability of the hangingwall depositional systems and the types of resulting deposits (i.e., fault-controlled base-of-scarp, settling from suspension, and hangingwall-derived). After addressing the syn-rift tectono-stratigraphic framework, we suggest that periods of significant erosion along the Thebe-0 fault scarp are related to the accumulation of fault-controlled base-of-scarp deposits characterised by comprising a lower wedge with chaotic to low-continuity reflections. Footwall-derived deposits characterised by an upward decrease in stratigraphic dip are interpreted as related to periods of reduced fault activity and sustained sediment delivery sourced from the footwall scarp and systems beyond it (e.g., antecedent systems). We then analysed the tectono-stratigraphic framework and the volumetric comparison between material eroded from the fault-scarp and accumulated in the basin, aiming to estimate the contribution of fault-scarp degradation to the hangingwall syn-rift fill. Our results suggest periods of enhanced fault activity control fault-scarp degradation variability through time, and we agree with that described by previous researchers—fault throw variability along-strike regulates the variability in the magnitude of erosion. However, we propose that fault-scarp degradation timing and its spatial variability are also influenced by the interaction and linkage with adjacent normal faults and by sea level variations. Lastly, we determine broader similarities and differences with a system located in the same fault array (i.e., Thebe-2 fault system), aiming to give insights into the tectono-stratigraphic evolution of a broader area and the spatial variability in fault-scarp degradation.

How tectonic forcing, expressed as base level change, is encoded in the stratigraphic and geomorphic records of coupled source-to-sink systems remains uncertain. Using sedimentological, geochronological and geomorphic approaches, we describe the relationship between transient topographic change and sediment deposition for a low-storage system forced by rapid rock uplift. We present five new luminescence ages and two terrestrial cosmogenic nuclide paleo-erosion rates for the late Pleistocene Pagliara fan-delta complex and we model corresponding base level fall history and erosion of the source catchment located on the Ionian flank of the Peloritani Mountains (NE-Sicily, Italy). The Pagliara delta complex is part of the broader Messina Gravel-and-Sands lithostratigraphic unit that outcrops along the Peloritani coastal belt as extensional basins have been recently inverted by both normal faults and regional uplift at the Messina Straits. The deltas exposed at the mouth of the Pagliara River have constructional tops at ca. 300 m a.s.l. and onlap steeply east-dipping bedrock at the coast to thickness between ca. 100 and 200 m. Five infrared-stimulated luminescence (IRSL) ages collected from the delta range in age from ca. 327 to 208 ka and indicate a vertical long-term sediment accumulation rate as rapid as ca. 2.2 cm/yr during MIS 7. Two cosmogenic ¹⁰Be concentrations measured in samples of delta sediment indicate paleo-erosion rates during MIS 8–7 near or slightly higher than the modern rates of ca. 1 mm/yr. Linear inversion of Pagliara fluvial topography indicates an unsteady base level fall history in phase with eustasy that is superimposed on a longer, tectonically driven trend that doubled in rate from ca. 0.95 to 1.8 mm/yr in the past 150 ky. The combination of footwall uplift rate and eustasy determines the accommodation space history to trap the fan-deltas at the Peloritani coast in hanging wall basins, which are now inverted, uplifted and exposed hundreds of metres above the sea level.

The Pannonian Basin System originated from the collision of the African and European tectonic plates, followed by the Miocene extensional collapse that led to the development of a back-arc basins. Accurate dating is essential to comprehend the tectono-volcanic evolution of the region, particularly in the under-studied Danube Basin. Single-grain ⁴⁰Ar/³⁹Ar dating has revealed that volcanic activity in the Danube Basin commenced around 14.1 million years ago, aligning with previous biostratigraphic and radioisotope data from nearby volcanic fields. The initial Middle Miocene pyroclastic deposits were generated by intermediate high K calc-alkaline magmas, contributing significantly to the deposition of thick layers of fine vitric tuffs. The timing and chemistry of the volcanism are consistent with the Badenian rift phase in the Middle Miocene within the Carpathian–Pannonian region, suggesting an intraplate back-arc volcanic environment. Three-dimensional imaging has exposed the buried Kráľová stratovolcano, revealing its impressive scale with a thickness between 2620 and 5000 m and a base diameter of 18–30 km. Such dimensions place it among the ranks of the world's largest stratovolcanoes, indicating its substantial impact on the evolution of the Carpathian–Pannonian area. The complex formation history of the stratovolcano points to multiple phases of growth. Furthermore, the basin controlling Mojmírovce-Rába fault's intersection with the stratovolcano implies that fault activity was subsequent to the volcanic activity, being younger than 14.1 million years. Regional age data consistently indicates that volcanic activity in the Danube Basin reached its zenith just prior to and during the lower/upper Badenian sea-level fall (Langhian/Serravallian). K-metasomatism is unique to the stratovolcanic structures and is not observed in the wider regional setting. This study supports the notion of an intricate, interconnected subterranean intrusive system within the stratovolcano, underscoring the complex interplay between geological structures and volcanic processes.

The prolific hydrocarbon and geothermal potential of the Cooper–Eromanga Basin has long been recognised and studied, however, the thermal history which underpins these resources has largely remained elusive. This study presents new apatite fission track and U–Pb data for eight wells within the southwestern domain of the Cooper–Eromanga Basin, from which thermal history and detrital provenance reconstructions were conducted. Samples taken from sedimentary rocks of the upper Eromanga Basin (Winton, Mackunda and Cadna-owie Formations) yield dominant Early-Cretaceous and minor Late-Permian–Triassic apatite U–Pb ages that are (within uncertainty) equivalent to corresponding fission track age populations. Furthermore, the obtained Cretaceous apatite ages correlate well with the stratigraphic ages for each analysed formation, suggesting (1) little time lag between apatite exposure in the source region and sediment deposition, and (2) that no significant (>ca. 100°C) reheating affected these formations in this region following deposition. Cretaceous apatites were likely distally sourced from an eastern Australian volcanic arc, (e.g. the Whitsunday Igneous Association), and mixed with Permian–Triassic sediment sources from the New England and/or Mossman Orogens. Deeper samples (>2000 m) from within the southwestern Cooper Basin yielded partially reset fission track ages, indicative of heating to temperatures exceeding ca. 100–80°C after deposition. The associated thermal history models are broadly consistent with previous studies and suggest that maximum temperatures were reached at ca. 100–70 Ma as a result of hydrothermal circulation correlating with high rates of sedimentation. Subsequent Late-Cretaceous–Palaeogene cooling is interpreted to reflect post magmatic thermal subsidence and cessation of hydrothermal activity, as well as potential modified rock thermal conductivity as a response to fluid flow. Five of the seven modelled wells record a Neogene heating event, the geological significance of which remains tentative but may suggest possible reactivation of the Cooper Hot Spot and associated hydrothermal circulation.

Detrital zircon (DZ) U–Pb geochronology has improved the way geologists approach questions of sediment provenance and stratigraphic age. However, there is debate about what constitutes an appropriate sample size (i.e., the number of dates in a DZ sample, n), which depends on project objectives, sample complexity, and, critically, analytical budget. Additionally, there is ongoing concern about bias introduced by zircon grain size. We tested a recently developed rapid (3 s/analysis) data acquisition method by multicollector laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) that incorporates an automated selection routine and calculates two-dimensional grain geometry from polished sample surfaces. Eleven samples were analysed from below and above the Late Cretaceous (Campanian) basal Castlegate unconformity of the Book Cliffs, Utah, in a down-depositional-dip transect including Price, Horse, Tusher, and Thompson canyons. 12,448 new concordant dates were generated during two measurement sessions. Results are consistent with recent studies suggesting there is no major provenance change and little time (1–2 Myr) represented across the unconformity. Grain size and sample size both exert a strong control on sample dissimilarity. Age distributions constructed from subsamples of large grains are systematically less similar to whole samples; age distributions composed of small grains are overall more similar to whole samples. As such, North American sediment sources that produce large grains such as the Grenville and Yavapi-Mazatzal belts can bias age distributions if only large grains are analysed. A sample size of n = 100 is inadequate for characterizing age distributions as complex as those of the Book Cliffs, whereas a sample size of n = 300 provides good characterization. Sample size of n ≈ 1000 or more is unnecessary unless project objectives include scanning for subordinate age groups, such as when identifying the youngest grains for calculating a maximum depositional age (MDA). Dates used in MDA calculations acquired with rapid acquisition are best re-analysed with longer LA-ICP-MS acquisition methods or isotope dilution thermal ionization mass spectrometry for increased accuracy and precision. We include new MATLAB code and open-source software programs, DZpick and DZmda, for automated spot picking and calculating MDAs.

Submarine fluid flow system can transport methane into ocean. However, its evolution is not fully understood, particularly methane migration through the gas hydrate stability zone (GHSZ) in deep-water settings. Here, we used 3D seismic and well-logging data to show the currently active fluid flow system in the northern South China Sea. It was interpreted to have two parts and they together feed intermittent methane emission. Three gas clouds have been seismically imaged beneath the base of gas hydrate stability zone (BGHSZ) and a set of new faults can be identified within them. Twenty-eight seismic pipes were found to penetrate three vertically stacked mass transport deposits (MTDs) above the gas clouds. Log-seismic correlation shows that the seismic reflections in the pipe represent MTD sediment, bulk carbonate and gas hydrate- or free gas-bearing sediments. We interpreted faults and pipes as the main migration conduits below and above the BGHSZ respectively. The MTD within the GHSZ could seal the underlying free gas transported by faults and thus overpressure built up at the base prior to the occurrences of the pipes and the fracturing through the overlying sedimentary succession. Subsequently, focused fluid flow entered the GHSZ, with the methane probably bypassing the GHSZ before pore clogging of gas hydrates occurred. Additionally, mapping of high-amplitude reflections surrounding the upper portion of gas clouds reveals the relict free gas associated with three paleo-GHSZ bases. Episodic emplacements of new MTDs repeatedly caused the upward shifts of the BGHSZ and the resultant gas hydrate dissociation, contributing to methane emission. We proposed that the occurrences of MTDs may facilitate methane emission by intermittently trapping methane and inducing gas hydrate dissociation in deep-water settings.

Marginal and deeper marine facies typify the Miocene exposures along the western margin of the Gulf of Suez rift basin. The stratigraphic setting of these facies is a subject of debate and confusing at best. Integrative sedimentological and sequence stratigraphic study of successions exposed in the St. Paul and El-Zeit blocks provides insight into the lateral relationships between the two facies and their evolution, a topic that is not fully understood. The St. Paul block, located at the basin margin, has thin shallow marine facies, while the succession of El-Zeit block, situated near the basin axis, consists of basal conglomerates, thin shallow marine carbonates, thick deeper marine shale and marginal evaporites. The facies architecture of these successions is interpreted as belonging to two different depositional models: a fan-delta/lagoon system followed upwards by an alluvial fans/sabkha-tidal flat system in the St. Paul hangingwall basin, and carbonate–siliciclastic–evaporite systems on the hangingwall dip-slope ramp of El-Zeit block. These models may help understanding the sedimentary history of other similar blocks in the rift basin. The studied facies show many striking features such as deposition during tilting of fault block, abrupt facies and thickness variations, coarse clastic shedding, erosion channel filling, onlapping of high standing blocks and evaporite accumulation. These features are the result of major tectonic events that triggered the formation of unconformities at different hierarchical levels during the late early to middle Miocene. These unconformities subdivide the Miocene facies into five depositional sequences separated by basin-wide erosional boundaries. This division greatly improves the age control of marginal marine facies. It affords new insight into the evolution of marginal marine facies along the western margin of the basin in relation to deeper facies in the basin centre. Facies and thickness changes in these tectonically induced sequences indicate that basin floor irregularities, subsidence rates, climatic changes, variable sediment influx, sea-level/brine-level changes and basin isolation/connection to the Mediterranean Sea are also important factors responsible for their evolution.

The timing of the initiation of the present-day tectonic architecture and drainage systems in eastern China remains debated. This study presents a comprehensive provenance study of the Early Jurassic peripheral basins surrounding the Dabie orogen including framework petrography, heavy-mineral analysis, single-grain chronology and chemistry. Clasts of high-grade schist, muscovite grains, rare gneissic fragments, abundant metamorphic garnet and phengite (Si > 3.3 pfu), combined with a main 216–256 Ma rutile U–Pb population found in these Early Jurassic sandstones, indicate a source from the Triassic (U)HP belt in the Dabie orogen. Sedimentary lithics and ultra-stable heavy-mineral assemblages indicate an additional source of recycled sedimentary rocks. Combined with the continuous shift of the youngest detrital rutile age population toward younger ages toward the north that mimics the pattern of metamorphic bedrock ages in the Dabie orogen, we infer that the present surface tectonic architecture and paleodrainage patterns of the Dabie orogen were established in the Early Jurassic. Thus, the Early Jurassic exhumation of the Dabie orogen marked the development of the watershed between Northern and Southern China, namely the Huai River and several principal tributary systems of the middle-lower Yangtze River.