Basin Research最新文献

Continental rifts are characterized by up to 30 km wide rotated fault blocks with stratigraphic dip away from the central rift axis. Although gravity-induced mass movements are well known features of collapsed fault block crests, I here demonstrate the occurrence of polymodal gravity-driven mass transport down the back slope of a first-order rift fault block. I identify (1) early sliding related to syntectonic crestal collapse of second-order rift faults, (2) large-scale bed-parallel sliding of the L-M Jurassic sedimentary package, and (3) the accumulation of two 7 km long, 1–2 km wide and up to 750 m thick volumes of complexly slumped material in the hanging walls of two ramp-forming faults. Early sliding is documented by 100 m of repeated Brent Group stratigraphy in a cored well in the study area (well 34/4-15A). These smaller slides have intact internal stratigraphy but show elevated deformation band densities. The seismic data also show evidence for ca. 2 km of massive translational sliding of the ca. 400 m thick and ca. 300 km² large Jurassic section above a lowermost Jurassic bedding-parallel detachment. This translational slide did not deform much internally, except for ductile folding where it slid over underlying active rift faults. Chaotic seismic facies in fault hanging walls are interpreted as contorted Jurassic beds, formed by multiple slumping and sliding events that stacked mobilized sediments into a 750 m thick column. These complex slump volumes occur where fault displacement is highest along two relayed faults. A model is favoured where the large translational slide ruptured with an opening of space against the fault that was progressively filled with slumped material from the footwall. While the large-scale translational sliding only caused moderate internal subseismic deformation, early sliding and, particularly, the complex slumping caused significant internal deformation. This study shows the importance of carefully searching for and distinguishing between different types of mass movement in rift systems.

The McCoy Mountains Formation (McMF) in southern California–Arizona preserves an anomalously thick record of sedimentation during the Mesozoic at a critical time when western North America experienced contrasting tectonic events related to intracontinental rifting along the Mexican Border rift system and consolidation of the North American Cordilleran system. The spaciotemporal interactions among these events and the development of the McCoy basin challenge our understanding of the evolution of the southern extent of North America. At its type locality in the McCoy Mountains, the McMF consists of ~ 7 km of low-grade metasedimentary rocks, originally interpreted as meandering fluvial to alluvial-fan deposits. Uncertainty in the initial timing of sedimentation in the McCoy basin has resulted in multiple tectonic models. We measured ~ 7160 m of detailed stratigraphy and present new sedimentological and detrital zircon results showing that the McCoy basin was occupied by deep-water turbidite systems. These systems deposited an upward-coarsening succession of fine- to coarse-grained detritus during the Cretaceous (ca. 137–70 Ma). Provenance data indicate that the McCoy basin received sediment from Proterozoic basement rocks and metamorphosed Palaeozoic to early Mesozoic sedimentary units. These source rocks are equivalent to the stratigraphy found in the Grand Canyon and Colorado Plateau regions and were likely shed from the southward-advancing Maria fold-thrust belt and possibly the southern Sevier belt in southern Nevada and California. These results, combined with subsidence curves typical of foreland basins, favour deposition within a subaqueous flexural foreland basin system. The presence of a Cretaceous foreland basin this far southwest challenges previously proposed models and suggests that the contractional tectonic regime associated with the North American Cordillera extended into the southwestern most United States during the Early–Late Cretaceous.

The Neogene and Quaternary hinterland basins of the Northern Apennine have been the subject of different tectonic interpretations. Several studies considered these basins as the result of polyphase normal faulting framed in a continuous crustal extensional regime since the middle Miocene. On the contrary, geophysical and geological studies provided evidence of the important role played by out-of-sequence thrusts and backthrusts in the evolution of these basins during a prolongated and intense period of shortening. Here we present an integrated analysis of 2D stacked seismic reflection profiles, stratigraphic and geophysical data from deep exploration wells, gravity data, and published geological and biostratigraphic data for the Valdera-Volterra basin (central Tuscany, Italy). The results support a polyphase and composite evolution of the basin, subdivided into three main phases. During the late Tortonian–Zanclean, the growth of major thrust-related anticlines controlled the evolution of the sedimentary basin. The growth of a syncline determined the creation of accommodation space for the sediments. This main compressional deformation occurred during the Messinian and ended during the Late Zanclean. NE migration of the depocentre during the Early Zanclean was identified, likely possibly due to a differential activity growth between the bordering anticlines. During the Piacenzian, an extensional phase has been recognised, superposed to the previous compressive phase. During the Latest Piacenzian–Early Pleistocene (?), a final compressional phase took place resulting in the positive inversion of the Piacenzian WSW dipping main border fault.

A two-dimensional numerical analysis based on the finite element method and linear elasticity is used to demonstrate how the differential compaction of the basinal unit can cause the early deformation of a prograding and/or aggrading carbonate platform. Our model investigates the modification of the carbonate platform stratal architecture and stress field driven by the process of differential compaction. We compared the results of our model with observations from two Triassic carbonate platforms in the Italian Dolomites: Lastoni di Formin and Nuvolau Mts. (Passo Giau, Italy). We show that the model can explain the modification of stratal architecture, as well as fault and fracture patterns observed on these platforms. In particular, we show that (1) the slope and slope-to-basin transition regions are expected to experience most of the brittle deformation and, differently from what was suggested by previous numerical studies, the formation of platform-ward dipping faults and major fractures with dip angles that tend to decrease moving dip-ward. In addition, (2) the inner platform region can exhibit a slightly tensile regime, which may lead to the formation of syndepositional and/or syndiagenetic fractures. Moreover, (3) in the case of predominantly prograding platforms, the results of the model show a general tilting and thickening of the inner platform strata towards the shelf-slope break.

The value of deep-water sedimentary successions as reliable records of environmental change has been questioned due to their long response times and sediment pathways leading to complex responses to climatic change and tectonic signals over differing timescales. We studied the Gulf of Corinth, Greece, to test the value of deep-water stratigraphic successions as records of external controls on sediment flux in a setting with short response times and transport distances. The confinement of the rift basin allows for a near-complete accounting of clastic sediment volumes. The recent acquisition of high-resolution seismic reflection data, utilisation of International Ocean Discovery Programme Expedition 381 cores and a robust chronological framework, enable evaluation of the stratigraphy at a high temporal resolution. Combining borehole and high-resolution seismic reflection data, distinct seismic units can be correlated to multiple paleoenvironmental proxies, permitting quantification of sediment flux variation across successive glacial–interglacial cycles at ca. 10 kyr temporal resolution. Trends in average sediment flux since ca. 242 ka show ca. 2–9 times greater sediment flux in cooler glacials compared to warmer interglacial conditions. The Holocene is an exception to low sediment flux for the interglacials, with ca. 5 times higher rates than previous interglacials. The short and steep configuration of the Sythas canyon and its fan at the base of an active submarine normal fault results in deep-sea deposition at all sea-level stands. In contrast, adjacent canyon systems shut down during warm intervals. When combined with palynology, results show that periods of distinct vegetation re-organisation correlate to sediment flux changes. The temporal correlation of sediment flux to palynology in the Gulf of Corinth over the last ca. 242 kyr is evidence that variability of sediment supply is largely governed by climate-related changes in hinterland catchments, with sea-level and tectonics being second-order controls on sediment flux variability.

Rift initiation within cold, thick, strong lithosphere and the evolving linkage to form a contiguous plate boundary remains debated in part owing to the lack of time–space constraints on kinematics of basement-involved faults. Different rift sectors initiate diachronously and may eventually link to produce a jigsaw spatial pattern, as in the East African rift, and along the Atlantic Ocean margins. The space–time distribution of earthquakes illuminates the geometry and kinematics of fault zones within the crystalline crust, as well as areas with pressurized magma bodies. We use seismicity and Global Navigation System Satellites (GNSS) data from the Turkana Rift Array Investigating Lithospheric Structure (TRAILS) project in East Africa and a new digital compilation of faults and eruptive centres to evaluate models for the kinematic linkage of two initially separate rift sectors: the Main Ethiopian Rift (MER) and the Eastern rift (ER). The ca. 300 km wide zone of linkage includes failed basins and linkage zones; seismicity outlines active structures. Models of GNSS data indicate that the ca. 250 km-wide zone of seismically active en echelon basins north of the Turkana Depression is a zone, or block, of distributed strain with small counterclockwise rotation that serves to connect the Main Ethiopian and Eastern rifts. Its western boundary is poorly defined owing to data gaps in South Sudan. Strain across the northern and southern boundaries of this block, and an ca. 50 km-wide kink in the southern Turkana rift is accommodated by en echelon normal faults linked by short strike-slip faults in crystalline basement, and relay ramps at the surface. Short segments of obliquely oriented basement structures facilitate across-rift linkage of faults, but basement shear zones and Mesozoic rift faults are not actively straining. This configuration has existed for at least 2–5 My without the development of localized shear zones or transform faults, documenting the importance of distributed deformation in continental rift tectonics.

Landscapes are the integrated product of external forcings (e.g. tectonics and climate) and intrinsic characteristics (e.g. bedrock erodibility). In principle, hard bedrock with low erodibility can steepen rivers in a similar way to tectonic uplift. A key challenge in geomorphic analysis is thus separating the tectonic and lithological effects on landscapes. To address this, we focus on multiple rivers that are transiently incising through contrasting lithologies in the Gulf of Corinth, Greece, where tectonic history is broadly well constrained. We first exploit topographic metrics and river long profiles to demonstrate that landscapes are responding to both tectonics and lithology. In particular, the long profiles are divided into knickpoint-bounded segments, and at this scale, channel steepness is shown to be more sensitive to lithology than the entire catchment, possibly due to relatively uniform erosion rate at the segment scale. We then use segment-scale steepness variations between different lithologies to constrain their relative erodibilities (K_lime:K_cong.:K_sand-silt:K_{p-con sed.} = 1:2:3:4), which are further converted into actual lithology-dependent erodibilities by modelling a well-constrained, ca. 700 ka knickpoint in the Vouraikos catchment. The effectiveness of lithology-dependent erodibilities is supported by the observation that if lithology-dependent erodibilities are used to calibrate studied river long profiles in χ distance, we obtain long profile concavities that fall within the theoretical range. Finally, we use lithology-calibrated metrics to provide new geomorphic constraints on the timing and magnitude of tectonic perturbations in these catchments. These geomorphic results are interpreted in conjunction with previous onshore and offshore studies to shed new light on fault growth and linkage history in the Gulf of Corinth. Our study therefore provides a topographic analysis-based approach to quantify lithological effects on transient catchments, with important implications for tectonic interpretations of topographic metrics in lithologically heterogenous landscapes.

Nummulitic Limestones deposits are preserved along the tectonic contact between the Variscan basement and Alpine units of Corsica. These marine carbonates, dated from the Late Palaeocene to the Middle Eocene, were deposited within a foreland flexural basin that is considered to be the southern continuation of the Alpine foreland basin of southeast (SE) France. However, in contrast with the Nummulitic Limestones of SE France, those of Corsica are far less documented. This field-based study constrains the sedimentology, stratigraphy and structure of the Nummulitic Limestones of Corsica in three localities (Balagne, Corte and Sari-Solenzara) to identify factors that controlled foreland basin development and to clarify its significance within the early alpine orogen. The microfacies, microfaunal assemblages and siliciclastic fractions are characterised throughout the succession at each locality. The results indicate the existence of an important Variscan basement relief to the west of the basin (West Corsican Massif) that supplied early alluvial fans found at the base of the foreland succession in the northernmost Balagne area. Continuous high clastic input strongly reduced the development and diversity of the overlying Nummulitic Limestones facies and fauna. Further south, limestones in the Corte and Sari-Solenzara areas are thicker and contain richer fauna. Three depositional models corresponding to the carbonate ramp system are proposed for the Nummulitic Limestones and used to construct paleogeographic maps illustrating the transgressive evolution of the Corsican foreland basin from the Early to the Late Eocene. Based on our results and available regional tectonic data and LT thermochronological data, we propose that the Nummulitic marine transgression took place within a continuous foreland basin encompassing southern Corsica and SE France during the early development of the western alpine arc.

This study focuses on the Late Palaeozoic development of the area east of Utsira High in the North Sea, where the stratigraphic section below the late Permian Rotliegend Group is undrilled. We use regional 3D seismic data to study structuring, sediment distribution and geomorphology across the Patch Bank Ridge and Utsira High in the North Sea. The results show that the Stord Basin and the bounding Utsira East fault initially developed during the Late Palaeozoic extension, probably during the Devonian, and that the Utsira Shear Zone controlled the location of Late Palaeozoic depocentres. The Patch Bank Ridge is an uplifted part of the Stord Basin where we identify Late Palaeozoic growth strata along the southern and northern flanks, indicating a similar timing of the structural evolution in this area. Two key wells, in the Sele High and Ling Depression, are used to relate a Late Palaeozoic isopach map with regional structuring, surface tilt and basement morphology to the enigmatic parts of the Late Palaeozoic basin system. Our results supplement regional models for the Late Palaeozoic basin development, we suggest that the deeply eroded Devonian half-grabens preserved on the Utsira High formed parts of an extensive basin system that show stratigraphic expansion towards their bounding faults. The Top Basement surface at these highs offers several distinct geomorphologies that evolved during three periods of exposure, expressed as (i) a tilted and rugose landscape, (ii) distinct drainage networks and (iii) peneplain surfaces. Cover sediments place these landscapes to the (i) Devonian, (ii) Carboniferous/Permian/Triassic and (iii) Late Triassic periods.