Terrace Staircases Research Articles

Quaternary tectonic and climatic forcing on the spatio-temporal evolution of the Meuse fluvial terrace staircase

The Quaternary is characterized by pronounced alterations between cold and warm climatic states, with the Mid-Pleistocene Transition marking a strong increase in the intensity of cold-climate conditions. River systems are sensitive to environmental perturbation (e.g., climate, tectonics, base level) and are expected to respond to such profound changes. This study uses a combination of terrace mapping and analysis of a dense borehole database to investigate the Meuse terrace staircase (and its deposits), and gain insight on how it reflects climatic and tectonic perturbations during the Quaternary. The lower reaches of the Meuse river, which has both its main water and sediment source in the Ardennes displays a well-developed terrace staircase that was sculpted mainly throughout the Quaternary. The staircase is located near the cities of Maastricht (southern Netherlands) and Liège (northwestern Belgium). About 30 terrace levels reflect signals of environmental perturbations in the lithological composition, gradients, thicknesses, and spatial distribution. The terraces are organized in groups, based on their morphological position, from old to young; these are the East Meuse terrace group and West Meuse High-, Middle- and Low terrace groups. Our findings show a consistent increase in the gravel content from older to younger terraces. The sandier composition of the deposits of the oldest terraces (Early Pleistocene) is closely related to the supply of the Miocene-Pliocene weathered material from the Ardennes. Younger terraces (Middle and Late Pleistocene) are much richer in gravel, evidencing sediment input from fresh or partially weathered bedrock. These changes point to a downstream migration of the gravel front throughout the Quaternary. The mean thickness of the terrace groups shows a slight increase, even though the same trend is not clear when each terrace is analyzed on an individual basis. The anomalous thickness of the Caberg 1 terrace suggests increased sediment input during the cold climatic conditions of the Elsterian (MIS 12), the first Quaternary glacial during which an ice sheet extended into the northern Netherlands. Reconstruction of terrace gradients reveals that older East Meuse terraces show a (reversed) gradient opposite to reconstructed palaeo flow directions, which is attributed to a combination of low gradients during terrace formation and footwall back-tilting of the Feldbiss Fault Zone. In our analysis we do not see clear evidence for the imprint of the Mid-Pleistocene Transition, which suggests that due to its gradual nature, its signal is either buffered or assimilated by the overall climatic signal of the Quaternary. This study offers a first complete temporal analysis of the Meuse terrace staircase, providing an important basis for better understanding the effects of Quaternary climatic change and tectonics, and their resulting effects in other river systems worldwide.

The onset of Pliocene–Early Pleistocene fluvial aggradation in the Southeastern Alpine Foreland (Velenje Basin, Slovenia) and its paleoenvironmental implications

ABSTRACTIn this study, we focused on the Pliocene–Early Pleistocene fluvial terraces in the Velenje Basin and reconstructed the morphostratigraphy, sedimentary depositional environment, provenance and age of the gravel deposits using geomorphological, sedimentological, petrographic and chronological analyses. Geomorphological mapping revealed the presence of two main river‐terrace groups. The terraces in the older terrace group are severely degraded and preserved only as remnants capping high ground, while in contrast the younger group is better preserved. Detailed lithofacies analyses of four selected stratigraphic sections of the older terrace group show that the gravel was deposited in a meandering and wandering environment. The gravel consists of metamorphic, igneous, volcaniclastic, clastic and carbonate lithologies derived from the north, east and west from the Paka River catchments. To determine the timing of deposition, we performed isochron‐burial dating using cosmogenic 26Al and 10Be. Our new age constraints date the deposition of the older terrace group to 2.7 ± 0.3 Ma. Establishing the aggradation and incision model of the Velenje Basin documents pronounced regional tectonic uplift during the Pliocene–Early Pleistocene, which led to incision and the subsequent formation of a terrace staircase.

Lithological controls on the timing of strath terrace staircase formation in a collisional mountain belt

AbstractIn mountain belts, strath terrace staircases serve as markers for deriving river incision rates and erosional patterns. Distinguishing between terrace patterns influenced by external perturbations like changes in climate and tectonics and those driven by internal dynamics including feedbacks between topography, erosion and sediment transport remains challenging. We demonstrate that in a collisional mountain belt, lithology can act as a first‐order control on the spatial and temporal scales of strath terrace formation. Here, we investigate the role of lithology in modulating internal dynamics and the formation of strath terraces in the Mgoun River catchment of the High Atlas in Morocco, a region characterised by constant low‐rate rock uplift, a cyclical cool‐warm/arid‐humid Quaternary climate history and contrasting bedrock lithologies. By collecting (1) modern river and terrace clast data, (2) bedrock strath and strath‐top sediment elevations of four terrace levels, (3) terrace sedimentology and (4) integration with published terrace chronology, we found a dominance of local sediment input from hillslopes, mostly from recycled bedrock conglomerates. Additionally, we found valley width, controlled by the stratigraphic and structural configuration of lithological erodibility, significantly impacts sediment connectivity. The isolation between valleys with varying widths results in varied timescales of river channel response to hillslope coupling, with hillslope‐derived stochastic sediment gravity flows preserved in fluvial terraces in some river reaches and not in others. Furthermore, asynchronous terrace formation and abandonment ages result from the low longitudinal river connectivity between multiple valleys formed in erodible rock separated by gorges in high‐strength rock. These gorges limit knickpoint migration rates, inhibiting the ability of terraces formed in one valley to spread through the catchment. These findings can inform future research distinguishing between autogenic and external signals in erosional landscapes and help carefully derive river incision rates and climate insights from terraces.

The timing of resurfacing events in Southern Kasei Valles

The second-largest outflow system on Mars is Kasei Valles. The southern branch of Kasei Valles includes two inner channels among the best-preserved examples of glacial and/or fluvial erosion. This study focuses on the landforms formed by surface processes within the midstream part of the southern branch of the Kasei Valles. We mapped the landforms and built a morpho-stratigraphical chronology using their cross-cutting relationships, and numerical crater dating. We interpret a complex geomorphological history, with various landforms in the study area, including fans, landslides, topographic barriers, strandlines, terraces and deeply incised canyons. Two coluvaial fans and a large landslide temporarily blocked the valles, forming topographical barriers to impound fluids (e.g., lava, mudflow, water). It has been suggested that the structures observed in the channels were formed by Bingham or Newtonian fluid. However, these fluids have disappeared but they have left the terraces and strandlines as their geomorphic imprints. The surface texture of the terraces implies that they were probably formed by a very low viscosity fluid that carved the fan, valley floor and formed terrace staircases and deep canyons. Crater statistics reveal two different temporal clusters of colluvial fan formation. The age of the older fan cluster in the Early Amazonian period, and the age of the younger fan cluster in the Late-Middle Amazonian period. The landslide is much younger and estimated to have formed 122 Ma ago, allowing us to constrain the timing of the latest erosional period. The youngest studied geomorphic features are the platy-textured deposits emplaced either as lavas or mudflows, aged 90 Ma, covering the floor of the valles. The strandlines defining the limits of the youngest erosional (thermal) process within the study area truncate the landslide but not the platy-textured features. Therefore, they are older than 90 Ma but younger than 122 Ma, implying environmental conditions sufficient to have allowed a liquid fluid body at the Martian surface during the Latest Amazonian period. Our data suggest that the presence of well-developed terraces between strandlines requires the presence of a fluid (e.g. water, liquid lava, mud) that ponded and subsequently evacuated from the study area.

The contribution of Rob Westaway to the study of fluvial archives

Robert Westaway was a structural and hard-rock geologist who turned his attention to the study of Late Cenozoic fluvial archives, believing that the preservation of staircases of river terraces, particularly representing the Middle and Late Pleistocene, could only be explained in terms of crustal activity in response to surface processes, the latter affected by climatic change. His entry into this research area coincided with the realisation that such terrace sequences required surface or crustal uplift to have taken place over the time interval represented. Workers were unable to explain the observed amounts of uplift in terms of erosional isostasy, a process that could potentially have explained such one-way crustal movement. Westaway envisaged a mechanism by which mobile lower crust migrated to beneath uplifting areas, maintaining and reinforcing their uplift. The mechanism requires complex mathematics to explain it, as well as lending itself to mathematical modelling of the process, based on varying crustal properties and changes in the rates of surface processes in response to climatic fluctuation. Essentially the lower-crustal effect can be envisaged as a positive-feedback enhancement of erosional isostasy.It became apparent that Westaway's theories could explain geomorphological and sedimentary fluvial archives that were otherwise difficult to elucidate. Mantle-based erosional isostasy could not explain terrace staircases, for example. Many of these occur in regions that are tectonically inactive, and so cannot be attributed to neotectonic activity. A game-changer in terms of persuading the wider community came from the recognition of crustally ultrastable regions in which progressive long-timescale uplift has not occurred: Archaean cratons. Westaway's envisaged lower-crustal flow would not be expected in such regions, which have cold, brittle and immobile crust to its full depth. Ancient fluvial deposits are found close to modern valley-floor levels in such areas. Regions of younger Precambrian crust (Proterozoic) showing intermediate situations were subsequently identified. Other dilemmas could be resolved, such as the ‘back-tilting’ of the early-Middle Pleistocene Bytham River in the English Midlands, caused by its drainage crossing crustal blocks with different properties that have accordingly experienced differential uplift. Although glacio-isostasy, mostly seen in the effects of rebound since the Last Glacial Maximum (LGM), is largely accommodated in the mantle, and thus is reversed as a response to glacial loading and unloading, in areas of suitable crustal type there is evidently a small lower-crustal component that is less readily reversible.Westaway's important contribution has yet to be fully integrated into received wisdom in geomorphological and Quaternary circles, although much of it is now widely accepted and more will be explored and published in due course.

Uplift rate calculation based on the comparison between marine terrace data and river profile analysis: A morphotectonic insight form the Ionian coastal belt of Basilicata, Italy

Geomorphological analyses of a wide coastal belt between northern Calabria and Puglia, where a well-exposed staircase of marine terraces extensively crops out, were performed in order to unravel the uplift history of this key-area. As a matter of fact, the Ionian coast of southern Italy represents a strategic sector for investigating the middle-late Quaternary morphotectonic evolution of the orogenic system of southern Italy.The main goal of our research was the reconstruction of a detailed uplift history using spatial distribution of marine terraces and river profile inversion. This was achieved by producing a new, detailed and complete map of the entire sequence of marine terraces and associated palaeoshorelines along the entire coastal sector. A critical review of the literature related to geochronological data from the study area, integrated with a modeling of the interaction between eustatic changes and tectonic uplift allowed demonstrating that the different terraces are correlated to many highstand peaks, dating the highest/oldest terrace to mid-Pleistocene times. Additional constraints on the spatio-temporal variation of tectonic uplift (or base-level fall) have been derived from the inversion of longitudinal river profiles. Such an approach adopts an independent geomorphic marker than the marine terraces and allowed us to obtain an additional estimation the uplift history of the area. The uplift values from the two methods differ in some cases by an order of magnitude, which could be attributed to the rigorous assumption of the river profile inversion or a limitation related to the chronological scheme of marine terraces.Our results highlight a spatial and temporal variation in the uplift rates, which can be only explained with a morphotectonic framework and likely the whole chain-foredeep-foreland system, remained under a prevailingly compressional tectonic regime during the Quaternary, with significant consequences for the seismic hazard of the region.

A fluvial record of late Quaternary climate changes and tectonic uplift along the Marche Piedmont Zone of the Apennines: New insights from the Tesino River (Italy)

Fluvial terraces are a pre-eminent continental record of climate changes and tectonics. Although the use of fill terraces for incision rate derivation is complicated due to their cyclical nature relative to strath terraces, they remain a relatively complete record of incision and deposition, thus allowing one to derive interpretations about both tectonics and climate. The Adriatic piedmont of the Apennines (central Italy) offers a well-preserved staircase of such terraces, caused by the cyclical alternation of fluvial aggradation and incision over the Middle and Late Pleistocene in response to a combination of low-rate tectonic uplift and climate changes. Although the staircase has been already widely described with examples from several valleys of the Adriatic Piedmont, its geochronological constraints are limited and must be enhanced to extract reliable climatic and tectonic signals from terrace deposits—especially for the older terrace levels.This research provides new Optically Stimulated Luminescence (OSL) data on the terrace chronology in combination with new semi-automatically extracted data on the altimetric and along-valley terrace distributions, as well as the sedimentological characteristics of fill terraces within the Tesino River basin in the Marche piedmont zone of the Apennines. The semi-automatic extraction of the terrace tread allowed a preliminary level classification as a function of the terrace height above the modern channel thalweg. The results demonstrate that, within the slowly uplifting Adriatic piedmont of the Apennines, the main phases of fluvial aggradation occurred during cold and full-glacial conditions followed by river incision and floodplain-channel abandonment during warmer periods. This finding confirms previous results from the last fluvial aggradation-incision cycle (Late Pleistocene). The results also show that the same formation mechanism is valid for the older (Middle Pleistocene) terraces. Indeed, this study provides new geochronological constraints for the regional-scale paradigm of cyclical formation and development of Quaternary fill terrace staircases along this sector of the Apennines. The use of a dated fill terrace staircase allowed estimation of a Middle Pleistocene long-term bedrock incision rate ranging from 0.3 to 0.5 mm yr−1 in agreement with previous studies in the central-northern sector of the Adriatic Apennines. The resulting uplift rate supports the presence of differently uplifted blocks due to the fragmentation of the peri-Adriatic region caused by the activity of left-lateral faults.

Quantification of short‐term transformations of proglacial landforms in a temperate, debris‐charged glacial landsystem, Kvíárjökull, Iceland

AbstractProglacial areas are dynamic landscapes and important indicators of geomorphic changes related to climate warming. Systematic and repeat surveys of landforms presently evolving on glacier forelands facilitate the quantification of rates of change and an improved understanding of the processes generating those changes. We report short‐term (2014–2022) transformations of the proglacial landscape in front of Kvíárjökull, SE Iceland, and place them in a longer‐term context of glacial landsystem evolution using aerial image archives since 1945. Short‐term quantification uses a time series of uncrewed aerial vehicle (UAV) surveys, processed utilizing a structure‐from‐motion (SfM) workflow, to produce digital elevation models (DEMs) and orthophoto mosaics. The land elements surveyed include a kame terrace staircase, an outwash plain, an ice‐cored hummocky moraine complex and ice‐cored hummocky terrain with discontinuous sinuous ridges, for which elevation and volumetric changes are quantified. The kame terraces between 2014 and 2022 and the outwash plain between 2016 and 2022 were mainly stable with, respectively, 87% and 85% of their surfaces showing no change. The ice‐cored hummocky terrain with discontinuous sinuous ridges underwent a volume loss of 64,632 m3 in 2016–2022, with a maximum surface lowering of ≤9 m. The most dynamic land element was the ice‐cored hummocky moraine complex, with transformations recorded for more than 87% of its area in 2014–2022; the surface was lowered by ≤23 m in some places, with a total volume loss of 365,773 m3. Our results confirm the ongoing degradation of ice‐cored moraine and outwash complexes at variable rates related to buried ice volume and age of deglaciation. The evolution of chaotic hummocky terrain from debris‐covered glacier ice, glacitectonic thrust masses, outwash fans/heads and complex englacial esker networks is an important modern analogue for informing palaeoglaciological reconstructions.

Quaternary Earth-science and Palaeolithic conservation initiatives in the Tejo (Tagus), Portugal: Comparison with the Lower Thames, UK

Geoconservation measures in the River Tejo, the Portuguese reach of the Tagus, are compared with those in the Thames downstream of London (UK). Both are fluvio-estuarine reaches with staircases of Pleistocene depositional terraces, each with important sedimentary, palaeontological and archaeological records. In both rivers, conservation measures are in place that aim to protect these records, promote research and inform the public. Inevitably there are differences in approach. Whereas Thames Quaternary interests are protected by a network of British statutory site designations, outreach is to the fore in the Tejo. Contrasting examples are highlighted here. The Tejo has interpretative materials in local museums and detailed explanatory displays at the low-terrace archaeo-geological site of Foz do Enxarrique, near the border with Spain, and at other sites. The Thames, in contrast, has few examples of physical outreach provision and limited formal protection for Pleistocene archaeological material outside the geological network, although extensive informal protection is provided by interaction between local geological groups and county and local-authority administrations. There is also a considerable difference in the degree of threat, with the Tejo above Lisbon being a relatively undeveloped valley, albeit with sporadic quarrying for aggregate, whereas the Lower Thames is an established area for infrastructure development, lying to the east of London, close to the river crossing of the orbital motorway. The different climate in the two regions profoundly influences the longevity of exposures in Quaternary deposits, with significant implications for management strategies. The comparison exercise reveals that each region would benefit from greater development of approaches used more prominently in the other; outreach measures in the Portuguese style would greatly enhance some of the Thames sites, but formal designation of Tejo exposures could prevent damaging operations being undertaken by owners who lack knowledge of their value, as exemplified by a case study of sites at Alpiarça, ~130 km upstream from Lisbon.

An assessment of competing factors for fluvial incision: An example of the late Quaternary exorheic Moyobamba basin, Peruvian Subandes

Three competing factors for late Quaternary fluvial incision in the Moyobamba piggyback basin, located in the northeastern Peruvian Subandes, were investigated, namely base-level change as a result of basin opening, changes in the ratio sediment load:discharge (Qs: Qw) controlled by orbital and suborbital climate cyclicity, and thrust-related tectonic uplift. To assess the relative importance of these factors, the fluvial terrace staircases of five rivers were studied in terms of their sedimentology, stratigraphy and geomorphology. A new dataset of eight Optically Stimulated Luminescence (OSL) and four 14C ages shows that the final phase of endorheic alluvial fan aggradation lasted until 18.0 ± 1.4 ka, after which basin-wide incision occurred. Incision at the basin outlet as a result of adaptation to the new base level is decoupled from the observed incision in the middle and upper parts of the basin. There, incision is the result of a northwestward increase in uplift related to movements of the Cerro Blanco thrust at the western border of the Moyobamba basin. Incision was continuous from 18 ± 1.4 ka until 10.3 ± 0.7 ka without terrace formation, but between 10.3 ± 0.7 ka and 5.5 ± 0.4 ka up to four terrace levels were formed. Deposition of fluvial terrace sediments may have occurred during short periods characterised by a more intense South American Summer Monsoon (SASM) controlled by suborbital climate cyclicity, but a more precise age control is needed to confirm this theory. Precession-controlled, increased Holocene aridification between 10.3 ± 0.7 ka and 5.5 ± 0.4 ka may have resulted in a decrease in the ratio Qs: Qw leading to a five-fold increase in fluvial incision rates of up to 6.0 mm a−1 and flattening of terrace profile gradients with rates of up to 2.6 mm a−1. After 5.5 ± 0.4 ka, rates dropped again. Over longer timescales, movement of the Cerro Blanco thrust caused basin-wide uplift and fluvial incision at a more constant pace. During the past ~20 ka, incision increases from the southwest basin border towards the northwestern basin border with corresponding uplift rates increasing from 0.2−0.2+0.3 mm a−1 to 2.1−0.2+0.2 mm a−1; and with shortening rates increasing northwestward from 0.2−0.2+0.4 mm a−1 to 2.8−0.2+0.3 mm a−1. The highest, presented uplift rates are in agreement with independently published data for our study area. Our data shows that over longer timescales of ~20 ka, incision rates can be used as proxies for tectonic uplift, but over shorter timescales incision rates may be seriously affected by climate change and cannot be used to infer uplift rates. It is further suggested that continuous uplift and erosion of the Cerro Blanco thrust system, and subsequent sedimentation in the basin, in combination with increased precipitation during Heinrich events 1 and 2 and the Last Glacial Maximum (LGM), led to basin overflow. Simultaneously, river capture through headward erosion, guided by strike-slip faulting, may have led to the definitive opening up of the Moyobamba basin. To our knowledge, this is the first time that late Quaternary basin opening has been demonstrated for the South American Andes and one of the few, known cases worldwide.

Post-collisional mantle delamination in the Dinarides implied from staircases of Oligo-Miocene uplifted marine terraces

The Dinarides fold-thrust belt on the Balkan Peninsula resulted from convergence between the Adriatic and Eurasian plates since Mid-Jurassic times. Under the Dinarides, S-wave receiver functions, P-wave tomographic models, and shear-wave splitting data show anomalously thin lithosphere overlying a short down-flexed slab geometry. This geometry suggests a delamination of Adriatic lithosphere. Here, we link the evolution of this continental convergence system to hitherto unreported sets of extensively uplifted Oligocene–Miocene (28–17 Ma) marine terraces preserved at elevations of up to 600 m along the Dinaric coastal range. River incision on either side of the Mediterranean-Black Sea drainage divide is comparable to the amounts of terrace uplift. The preservation of the uplifted terraces implies that the most External Dinarides did not experience substantial deformation other than surface uplift in the Neogene. These observations and the contemporaneous emplacement of igneous rocks (33–22 Ma) in the internal Dinarides suggest that the Oligo-Miocene orogen-wide uplift was driven by post-break-off delamination of the Adriatic lithospheric mantle, this was followed by isostatic readjustment of the remaining crust. Our study details how lithospheric delamination exerts an important control on crustal deformation and that its crustal signature and geomorphic imprint can be preserved for millions of years.

Late Pleistocene-Holocene characteristics of the North Anatolian Fault at Adapazarı Basin: evidence from the age and geometry of the fluvial terrace staircases

The Late Pleistocene-Holocene evolution of the Adapazarı Basin was investigated using the stratigraphy, geometry, and absoluteluminescence dating of the 4-step fluvial terrace staircases of the Sakarya River. The results revealed that the fluvial cycle was primarily related to relative sea level changes of the Black Sea. The initiation of deposition and the abandonment ages of the terraces indicated relative high stands during marine isotope stage (MIS) 5a (~84-72 ka), 3 (40-30 ka), and 1 (9 ka-recent). The erosional periods in between the terrace steps reflected the response of the Sakarya River to the significantly low stands of the sea. The spatiotemporal position of the high terraces (T4 and T3) yielded an average of 0.78 ± 0.03 mm/year, and uniform and aseismic rock uplift rate for the NW part of the Anatolian Plate bounded by the North Anatolian Fault, which ruptured during the 1999 İzmit earthquake. The lower terrace (T1) was previously used to determine the horizontal slip rate of the Sapanca-Akyazı segment of the earthquake rupture and reported as 16.7 + 3.6/-2.5 mm/year. Further displacement measurements from the surfaces of T2 and T1 yielded a vertical slip rate of 1.49 ± 0.2 mm/year, calculated for the Late Holocene. Extrapolation of these 2 vertical rates to the south and north of the fault zone, in time and space, used in conjunction with the stratigraphy and geometry of the Adapazarı Basin, provided an estimation constraining the timing of the initiation of the fault to 450 ± 50 ka and the total thickness of the basin to ~1100 m.

Estudio de la evolución cuaternaria de un modelado fluvial escalonado intramontañoso mediante índices morfométricos: río Lozoya, Sistema Central Español

Los índices morfométricos son descritos como herramientas útiles para comprender la evolución geodinámica de diferentes regiones geológicas, aunque suelen aplicarse considerando sólo la geometría actual de las formas del relieve. En este trabajo, hemos combinado una cartografía geomorfológica detallada & algunos de los índices y variables morfométricas más relevantes (Vf, Índice-T, SL, concavidad, elevación y pendiente), para cuantificar la evolución del río Lozoya. Estos índices fueron calculados usando no sólo las formas actuales del relieve, sino también para diferentes periodos. Este es el caso del índice Vf, cuyos valores fueron calculados a lo largo del tiempo, utilizando la paleotopografía definida por las terrazas fluviales rocosas del río Lozoya. Estas técnicas fueron aplicadas a la sequencia de terrazas rocosas del río Lozoya por medio de SIG y herrameintas estadísticas. El área de trabajo se ubica en una depresión tectónica intramontañosa delimitada por alineaciones pop-up (Sistema Central Español). El análisis geomorfométrico ha revelado una evolución Cuaternaria compleja controlada y condicionada por factores como las principales, estructuras Alpinas, la litología de subsuelo, la geomorfología regional, el levantamiento regional y el clima. En la cuenca de drenaje del Río Lozoya, los valles más incididos y estrechos se localizan aguas abajo, asociados con cambios litoestructurales y capturas fluviales, mientras que los valles más amplios se localizan hacia la zona de cabecera, relacionados con depresiones tectónicas pop-down. Por otro lado, el análisis del perfil longitudinal del Río Lozoya ha mostrado que los knickpoints mayores han persistido durante el tiempo, por lo menos desde el Mioceno Superior y sin aparentes signos de reactivación durante el Cuaternario. Finalmente, nuestro análisis revela que la formación y preservación de las terrazas erosivas están controladas por factores litológicos y morfoestucturales.

The polyphase rifting and inversion of the Danube Basin revised

Abstract To track the evolution and formation of one of the major sub-basins of the Pannonian back-arc basin system, we re-evaluate pre-rift, syn-rift, post-rift, and inversion stages of the Danube Basin. This synthesis builds upon a new compilation of (i) geophysical measurements, (ii) current data about the substratum of the basin, (iii) recent advances in stratigraphic architecture of the basin fill, (iv) subsidence history, (v) geomorphological evolution, and (vi) new biostratigraphic and geochronological data.The history of the basin begins with the pre-rift stage represented by the pre-Neogene basement, which belongs to an Eo-Alpine mountain range uplifted at the end of the Cretaceous. The core of the mountain range was formed by pre-Alpine high-grade metamorphic complexes, with a dome-like structure. The crystalline complexes were overlain by late Paleozoic and Mesozoic cover and nappes, which were later eroded during the early Cenozoic. These pre-rift processes were triggered by (i) the late Cenozoic collision of the Alpine-Carpathian orogenic wedge with the European platform, (ii) the crustal extension resulting from the northeastward lateral extrusion of the Alpine-Carpathian-Pannonian lithospheric microplate, and (iii) the subsequent updoming of the lithospheric mantle. This stage was followed by the polyphase rifting of the basin associated with extensive volcanic activity. This syn-rift stage consists of four phases. The first syn-rift phase dated to the early Badenian (~15.2–13.8 Ma), with subsidence documented in the Blatne and Želiezovce depressions, was characterized by accommodation rates up to ~900 m·Ma-1. The second syn-rift phase dated to the late Badenian (~13.8–12.6 Ma), exhibited accelerated subsidence with accommodation rates up to ~2300 m·Ma-1, and mainly affected the Blatne depression. The third and fourth syn-rift phases took place during the Sarmatian (~12.6–11.6 Ma) and early Pannonian (~11.6–9.5 Ma) and the accommodation rates reached ~900 m·Ma-1 and ~1000 m·Ma-1, respectively. They were documented in the Risňovce, Komjatice and Gabcikovo-Győr depressions, confirming the eastward subsidence migration, up to the external zone of the middle Miocene mantle upheaval. The late Miocene post-rift stage, commonly refered to as a thermal subsidence stage (~9.5–6.0 Ma), was associated with formation of a widespread planation surface called the “Mid-mountain level” on the margins of the basin. The history of the Danube Basin terminates with the inversion stage which began after ~6.0 Ma and is still ongoing. It includes the continuous uplift of the basin margins and the subsidence of the central depocenters. The fluvial depositional systems did not behave steadily, because (i) lateral channel mobility and area of deposition increased progressively until ~4–3 Ma and caused onlaps on the base of the succession, followed by (ii) gradual confinement of the streams to the central part of the basin by uplifting basin margins, recorded by formation of river terrace staircases.

Kızılırmak Nehrinin Denizel İzotop Katı 6 Sırasındaki İklim Değişimlerine Tepkisi

Bu çalışma Kızılırmak vadisinin Kapadokya yöresinde, Gülşehir-Tuzköy arasında kalan kesiminde yapılmıştır. Bu sahada T1’den (en yaşlı) T15’e (en genç) kadar numaralandırılmış 15 seki basamağı bulunmaktadır. Bu çalışmanın amacı, T13 sekisine (+15-20 m) ait üç lokasyonda Denizel İzotop Katı (DİK) 6 sırasında Kızılırmak Nehri’nin küresel iklim değişimlerine karşı tepkisini saptamaktır. Sekinin taban depolarından alınmış olan kum örnekleri pIRIR290 yöntemiyle 148 ±8, 154 ± 8 ve 159 ± 8 bin yıl (by) öncesine tarihlendirilmiştir. Önceki bir çalışmadaysa seki deposu kozmojenik izotop yöntemiyle 160±30 by öncesine tarihlendirilmiştir. Elde ettiğimiz veriler T13 teras depdepolarının birikimi öncesindeki ana vadi kazılmasının DİK 7 ve 6 (sıcak–soğuk) iklim geçişinde olduğunu göstemektedir. Veriler, T13 seki depolarının DİK 6’nın ilk evresinde biriktiğini ortaya koymaktadır. Ayrıca, T13 sekisinin ilk taşkınovası deposunda sıcak iklimi karakterize eden paleosolerin varlığı, seki deposunun alt kısmının olasılıkla DİK 6'nın erken evresinde (günümüzden önce 180 ile 165 bin yıl arasında) oluştuğunu gösterir. T13 sekisi depolarının yarılması ise DİK 6’nın sıcak periyodunun sonunda başlamış ve DİK 6’nın tam glasyal periyodunda tamamlanmıştır.

Dates and rates of endo-exorheic drainage development: Insights from fluvial terraces (Duero River, Iberian Peninsula)

Fluvial terraces are valuable records to study and characterize landscape evolution and river response to base level lowering, and to decipher coupled responses between fluvial incision and regional tectonics. The opening of closed basins has a strong impact on fluvial dynamics, as it involves an abrupt base level lowering that accelerates landscape fluvial dissection. This study focuses on the time response of the Duero Basin, the largest and best preserved among the Cenozoic basins of the Iberian Peninsula, to exorheism. Fluvial incision due to basin opening has developed up to 13 un-paired strath terraces along the south margin of the Duero river, distributed at relative heights up to +136–128 m compared to the modern floodplain. Paired 10Be26Al cosmogenic isotope depth profiles from six fluvial terraces, located ca. 30–80 km upstream from the opening zone, suggest Pleistocene ages for almost the entire fluvial terrace staircase (from T3 at +112 –107 m, to T12 at +13–11 m). The terrace density and the total lowering of the terrace surface, key parameters in limiting terrace exposure ages, were estimated based on field and geomorphological data. Apparent burial durations and basin denudation rates deduced from inherited 10Be26Al concentrations provide valuable information on basin evolution. Apparent basin denudation rates remained relatively low (<3–6 m·Ma−1) during the Pliocene, and doubled (8–13 m·Ma−1) during the Early Pleistocene (ca. 2–1 Ma) possibly showing a lower proportion of recycled sediments. Time averaged incision rates deduced from terraces in the study area and along some tributaries show that incision rates are higher close to the opening site (122–<250 m·Ma−1) than towards the upstream part of the catchment (88–68 m·Ma−1), evidencing the retrogressive travel of the erosive wave nucleated at the opening site.

Морфология погребенных долин ленского золотоносного района и связанные с ней особенности строения аллювиальных россыпей

In this article were summarized data of exploration work conducted in the valleys of the Lena gold-bearing area, starting from the early stages of exploration (1910–1920s) and ending with the 1990s, including large-scale production plans. the drainage system of the area inherits the faults that were formed in the late jurassic – early cretaceous. buried valleys inherit their position during several erosion cycles: in the same reaches the position and width of valleys of different ages remains approximately the same, but in the bottoms of valleys of different ages large transformations are observed. in the formation of the morphology of the buried valley of the Lena gold-bearing area, the leading role belongs to river channel processes. Stable position of the river valleys determines the inherited position of the placers, as a rule, they are located within the contours of the modern valleys or their bottoms, or are slightly shifted to terrace staircases. Inherited are also morphodynamic types of channels, however, in cases of displacement of the valleys to areas with different lithological and tectonic conditions, morphological structure of valleys and alluvial deposits also change. This leads to formation of beads-like widening of the valleys and steps in their longitudinal profiles. Specific examples of such changes are illustrated from the large valleys of the rivers vacha and bodaybo. Three types of buried erosional terraces were considered that alternate along the length of valleys and determine specific position of the placers. a significant influence of the major tributaries to the structure of placers was found that is expressed in the presence of a transverse to the axis of the valley of the gold-bearing layers and sudden changes of elevation values of their beds. the established regularities are relevant to other mining areas and may have great practical importance in prospecting and exploration of mineral deposits.

Morphostratigraphy and provenance of Plio‐Pleistocene terraces in the south‐eastern Alpine foreland: the Mislinja and Upper Savinja valleys, northern Slovenia

ABSTRACTThis study focuses on the Plio‐Pleistocene fluvial deposits preserved in the terrace staircases in the south‐eastern Alpine foreland of the Mislinja (MV) and Upper Savinja valleys (USV) in northern Slovenia. The area is located at the north‐eastern margin of the Adria microplate, where neotectonic activity is the prevailing driving force for the terrace formation. The aim of this study is to determine the morphostratigraphy and provenance of the Pliocene to Early Pleistocene gravels using geomorphic and clast lithological analysis. The established morphostratigraphic framework encompasses three terraces in the MV and five terraces in the USV. Due to the lack of age‐relevant data, the morphostratigraphy of the MV and USV is based on the results of geomorphic analysis, clast petrography and data from the literature. Low‐level, middle‐level and high‐level terrace groups were tentatively attributed to the Late and Middle Pleistocene, Early Pleistocene–Pliocene and Pliocene, and compared with the traditional Quaternary stratigraphy of the Alpine foreland. The results of the clast lithological analysis revealed major provenance areas. Moreover, the evolution of long‐term drainage from the Miocene onward was inferred, which suggests that the system reached conformity with the present‐day drainage pattern at the Miocene to Plio‐Pleistocene transition. Copyright © 2019 John Wiley &amp; Sons, Ltd.

Quaternary uplift along a passive continental margin (Oman, Indian Ocean)

Crustal movement along the coastline of the Arabian Sea in Oman is quantified along a 72km long coastal section characterised by staircases of marine terraces. An extensive topographic, geomorphological and geological survey was conducted on these terraces and an age model based on cosmogenic nuclide (10Be, 36Cl) and optically stimulated luminescence dating is presented, together with a new approach to extract palaeo-shorelines from a high-resolution digital elevation model. The uplifting crustal block is fault bounded and is composed of obduction related peridotites overlain by shallow marine limestone. Nine distinct terrace levels are identified and the results indicate continuous uplift between Marine Isotope Stage (MIS) 5a and MIS 19. The calculated uplift rates vary along the coastline and a northward tilting of the uplifted coastal block is interpreted as evidence for differential uplift. The geomorphology of the terraces proves that the tilting must have taken place after the last interglacial. Tectonic forcing of the uplift by a crustal forebulge associated with the Makran Subduction Zone is discussed. It is also concluded that the uplift involves processes of serpentinisation of the peridotites in combination with karstification of the overlying limestone formations. As water is essential for both processes, climate change during the Quaternary apparently played a significant role in the uplift process as well as hydro-isostasy.

Fluvial response to rising levels of the Black Sea and to climate changes during the Holocene: Luminescence geochronology of the Sakarya terraces

The Sakarya River is among the largest fluvial systems of the southern Black Sea basin, draining most of NW Anatolia. The river crosses the high relief of the Pontide mountain range through successive narrow gorges and strike-slip basins formed by the North Anatolian Fault (NAF) System. We have investigated this fluvial record along the course of the main river channel at its lower reaches. The study site is located south of the Adapazarı Basin, ~50 km inland from the Black Sea, where remnant floodplains are preserved as a three-step terrace staircase resulting from continuous uplift to the south of the NAF. The combination of high resolution mapping with a detailed luminescence (OSL and p-IR-IRSL) and radiocarbon geochronology has shed light on changes in the level of the Black Sea and in the hydrological system during the late Pleistocene to recent. The last glacial period is represented by the highest terrace (T3) indicating deposition during marine isotope stage (MIS) 3 in between two low stands of the Black Sea. Following a long-term erosional period initiated prior to last glacial maximum (LGM), the initiation of the deposition (T2) was synchronous with the proposed catastrophic sea level rise of the Black Sea (cal. C14 9.3 ka BP) which continued throughout the Holocene until the Roman warm period (1.8 ka BP). The late-Holocene to recent morphological evolution of the region is marked with two sequential erosional and depositional (T1 and T0) periods, which can be correlated with the well-documented historical climate shifts affecting the hydrological system. These results reveal that the erosional and depositional periods on the Sakarya River floodplain are controlled by major sea level changes and climatically induced fluctuations in discharge and sediment supply.