Fluvial Formation Research Articles

Spatial correlation between multiple geographical properties and the river density over the global martian surface

River valleys are prominent features of the martian surface. Exploring the properties correlated to the spatial pattern of the river density serves an essential role in understanding the water history on Mars. However, there is considerable debate regarding the properties related to the distribution of river density. We propose that these discussions arise from the complex interactions and the spatial heterogeneity of multiple properties. In our study, we employed the geodetector to examine the spatial correlation between the river density and multiple geographical properties including landform conditions, hydrous mineral, sedimentary fans, deltas, and lakes. Our findings reveal that the most correlated properties on river density vary by regions. And the explanatory power of an individual property was often enhanced in a nonlinear way when interacting with other properties. We hypothesize that the impact events were a major process responsible for global-scale fluvial valley formation on Mars. Furthermore, the local mechanisms of fluvial formation vary by region, reflecting regional differences in geomorphic, geological, and environmental conditions. The geodetector method provides new insights into exploring the controlling properties of the geographical processes on martian surface.

The Quaternary sequence of the Nahr el Kebir, NW Syria: An important repository for evidence of Palaeolithic occupation and landscape evolution in the eastern Mediterranean

The third largest river in Syria, the Nahr el Kebir has a well-preserved record of river-terrace deposits that have produced substantial Palaeolithic artefact assemblages both from within the terrace deposits and from the land surfaces above and around them. At the Mediterranean coastline, the fluvial gravels interdigitate with raised shoreline terrace deposits, providing an insight into the temporal and climatic relations of both of these important geomorphological and morphostratigraphical archives, as well as their relationship with each other. New research is reported here on the Pleistocene geology and geomorphology of the Nahr el Kebir and the associated Palaeolithic archaeology, the latter having been reinterpreted based on reassessment of museum collections arising from earlier detailed work. Field visits revealed an additional, hitherto unrecognized low-level river terrace, whereas one of the previously recognized Palaeolithic levels can be shown to coincide with slope deposits that armour hilltops rather than representing a genuine fluvial formation. The new understanding of these geomorphological and sedimentary archives supports ideas that this corner of the Mediterranean has experienced unusually rapid uplift during the recent Quaternary, as a result of which the local rivers, including the Kebir, have deepened their valleys rapidly. Consequently, only the recent part of the Quaternary is recorded in the Kebir system and the ages envisaged previously for the terrace deposits and the Palaeolithic artefact assemblages were considerable overestimates in many cases, a finding that has significance for their correlation with those from the wider region. Reassessment of the Palaeolithic archaeology suggests a settlement history initially dominated by groups using handaxes, alongside simple core working (0.5–0.3 Ma), followed by a major change with the appearance of Levallois core working alongside handaxes, marking the transition to the early Middle Palaeolithic.

LATERAL AND VERTICAL DISTRIBUTION OF TITANIUM-ZIRCONIUM MINERALS WITHIN OF THE ANDRIIVSKYI AND LIKARIVSKYI DEPOSITS (SOUTH-WESTERN PART OF THE NOVOMYRHOROD MASSIF)

General information on the geological structure and ore-bearing capacity of the Likarivske and Andriivske deposits, which are located in the southwestern part of the Korsun-Novomyrhorod pluton within the Novomyrhorod massif (South-Western part), is provided. The productive deposits of the Likarivske and Andriivske deposits are represented by the weathering crust formation and the continental alluvial sand-kaolin formation of the Lower Cretaceous (Aptian-Lower Albian). On the basis of the coordinates, description and results of testing wells, a target database was created. On the basis of this database, cartographic constructions were carried out. The structural (relief of the bottom and of the top surfaces of ore-bearing deposits and their thickness) and material (lithological composition of productive deposits; lateral distribution of the average content of ilmenite, zircon, rutile and apatite in productive deposits) parameters of different ages and different genetic formations of the Likarivske and Andriivske deposits were studied. The direction and strength of correlations between ilmenite, rutile, zircon, and apatite in the weathered crust and continental sediments (sands and redeposited kaolins) of the Lower Cretaceous were studied. It was established that within the limits of the Likarivske and Andriivske deposits, during the geological development of the territory, a zircon-apatite-ilmenite ore-bearing system of different time and different genetics was formed, which is represented by a spatial-paragenetic series: crystalline rocks of the foundation; weathering crusts of crystalline rocks of the foundation; fluvial formations formed due to erosion and redeposition of eluvium; fluvial formations that were formed due to erosion and redeposition of eluvium and Mesozoic-Cenozoic placers of different ages. The results of the research are an information base for supporting mining operations within the studied deposits.

Investigation of the Spatial Changes in Overbank Floodplains and Sedimentations on the Study Site of the Middle Tisza

River systems and their floodplains can be studied and evaluated according to different aspects. The natural processes of the Tisza were mostly influenced by the river training and levee construction works named after Vásárhelyi, as well as the main channel regulation works. After the construction of the embankments, the fluvial formation of the natural floodplains ceased, as these processes limited it to areas of the floodplain along the main channel. Another consequence of the river regulations is that the river is forced to deposit the sediment transported during the floods in this narrow floodplain causing increased filling up, so the role of floodplains in flood conveyance has increasingly been reduced. In this study, the author aimed to investigate the bed changes that occurred as a result of the river regulation works, as well as the sediment accumulation in the flood plain, focusing on a typical section of the Middle Tisza.

GEOLOGICAL STRUCTURE AND ORE-BEARING OF THE YURSKA AREA OF THE MEZHYRICHNЕ TITANIUM ORE DEPOSIT

Information on the geological structure of the Yurska area of the Mezhyrichnе titanium ore deposit is provided. It was found out that the geological structure of the site involves crystalline rocks of the foundation, their weathered crust and continental and marine deposits of different ages of the Mesozoic and Cenozoic: Lower Cretaceous continental (Irshan suite), Upper Cretaceous coastal marine (Moshno-Rudnyan suite), Paleogene (marine and continental), Neogene and Quaternary continental sediments. A useful mineral of the Jurassic area is ilmenite, which forms ore bodies in the crust of weathering of crystalline rocks of the foundation, sediments formed due to erosion and redeposition of eluvium (Irshan suite), as well as in rocks formed due to erosion of secondary ilmenite reservoirs (Moshno-Rudnyan suite and, to a lesser extent, heterogeneous genetic formations of the Quaternary system). The maximum content of ilmenite in the weathering crust is 430.2 kg/m3; in fluvial kaolins of the Irshan suite — 1447.4 kg/m3; in differently-grained sands of this suite — 506.2 kg/m3; in the sandy-siliceous horizon of the Moshno-Rudnyan suite — 256.7 kg/m3; in Quaternary loams and sandy loams — 146.4 kg/m3. The industrial placers of ilmenite are localized in the formations of the Irshan suite. Sandy-siliceous rocks of the Moshno-Rudnyan suite with an ilmenite content of more than 15 kg/m3 are included in the composition of the upper part of the industrial placer layer. On the basis of the coordinates, description and testing of the 1613 wells, a target database was created, on the basis of which a set of maps was built: maps of the lateral distribution of the average ilmenite content in the gruss of zone dezintegration of weathering rocks, in the kaolins of eluvial, in the fluvial kaolins and sands of the Irshan suite, and in the sandy-siliceous rocks of the Moshno-Rudnyan suite; maps of bottom and top surface relief and thickness of kaolins and sands of the Irshan suite and sandy-siliceous rocks of the Moshno-Rudnyan suite. The structural (nature of the relief of the bottom and top surfaces of ore-bearing deposits and their thickness) and material (lithological composition, distribution of ilmenite along the lateral and in the vertical cross-section of ore-bearing deposits) of placers parameters were studied. It was found that the relief of the bottom and of the top of the ore-bearing formations is uneven with local elevations and depressions. It was found that the content of ilmenite in the weathering crust increases, as a rule, up the section from the zone of disintegration and leaching to the zone of final hydrolysis and oxidation of weathering products. The vertical distribution of ilmenite in the Irshan and Moshno-Rudnyan rocks is uneven with a general tendency to decrease upwards along the section. Sometimes there are several enrichment horizons of insignificant thickness, or a significant content of ilmenite is present in the top of the rocks. Sometimes there are several enrichment horizons in the rocks, as a rule, in the lower and upper parts of the geological section. The directionality and strength of correlations between the relief of the sole and the surface, thickness and average content of ilmenite in ore-bearing rocks of different-ages and different-genetics of the Cretaceous system were investigated. It was found that the correlations have different directions and are mostly very weak, weak, sometimes moderate, medium and rarely strong. It was established that the distribution and content of ilmenite in the weathering crust is determined by its distribution and content in the crystalline rocks of the foundation. The distribution and content of ilmenite in the continental fluvial formations of the Irshan suite is determined mainly by the facies conditions of sedimentation and is rarely determined by its significant content in the underlying rocks. The distribution of ilmenite in the formations of the Moshno-Rudnyan suite is determined by the facies conditions of formation, and its content is determined by its content in the underlying rocks.

Middle and Late Pleistocene evolution of the Ardèche Valley archaeological landscapes (France)

Most archaeological and palaeo-environmental archives are preserved in specific environments (buried sediments, rock shelters, cave environments). Hence, the information we can obtain is usually incomplete, and lacking spatial and morphological significance. Studying landscape evolution can help us to understand the location and distribution of past societies and their relation to Quaternary environments. In the Ardèche Valley, most Middle and Late Palaeolithic sites are preserved in caves and rock-shelters and in rare cases in fluvial sediments. Here we apply an integrated geomorphological approach to the study of the evolution of the Ardèche Valley combining multi-method dating, geomorphological mapping and surveys of cave and fluvial formations. We review chronological results obtained through multi-method dating (electron spin resonance (ESR), infrared stimulated luminescence (IRSL), uranium-series (U-series), combined electron spin resonance/uranium-series (ESR/U-series)) on cave and riverine objects and combine them with topographic and stratigraphic observations in an integrated Bayesian hierarchical model. The results are in agreement with those obtained from other rivers in mountainous environment around the Mediterranean Sea and show sedimentation/incision phases that match the 100 ka glacial/interglacial cycles. The mean rate of river incision deduced from the established chronology for the Middle and Late Pleistocene period, 76 ± 7 m.Ma−1, shows adjustments to a moderate uplifting dynamic that shaped the main topographical features seen today in the landscape of the Ardèche Gorge. The spatially reconstructed alluvial features provide a palaeogeographic framework that can be used directly as a chronological and topographical constraint for archaeological research in the Ardèche catchment.

Postglacial outsize fan formation in the Upper Rhone valley, Switzerland – gradual or catastrophic?

AbstractOutsize fans are characterized by seemingly disproportionately small feeder catchments in relation to their fan area. Often having escaped rigorous scientific inquiry, the formative processes of these landforms remain inconclusive, supposedly ranging from catastrophic mass‐wasting processes to gradual fluvial formation. Here we apply a multi‐method approach, combining morphometric analysis with geophysical subsurface surveys and cosmogenic radionuclide exposure dating, to three outsize fans with hitherto unknown formation history in the Upper Rhone valley, Switzerland. Their feeder catchments are cut into bedrock hillslopes with a lack of indication of both pre‐existing catchment structures and/or unconsolidated material that was available after deglaciation.Focusing our study on the largest of these fans, our findings suggest a fan formation in three phases: In Phase 1, commencing after deglaciation at c. 10 ka and ceasing with full catchment development c. 6.0 ka, bulk fan bodies were established by deposits of massive high‐energy, high‐magnitude debris flows exporting sediment with average yields of up to 73 kt km−2 yr−1. In Phase 2, feeder basins were affected by comparatively lower‐magnitude debris flows that distributed a sedimentary facies of debris flow channels, snouts and large boulders across the initial fan. Over time, deposition rates quickly decayed and finally ceased c. 0.8 ka, when the system entered the present Phase 3, during which the fan‐surface consolidated and fan aggradation terminated. Low gradient and abundant still‐water deposits upstream of the fan still attest to the disruption of longitudinal sediment connectivity in the trunk valley.We conclude that outsize fan formation by massive debris flows in the Upper Rhone valley was rapid and massive, but incremental and non‐catastrophic. Given the delivery of material at extremely high rates, outsize fans are capable of having a sustained impact on geomorphic systems and, during phases of activity, potentially endangering human livelihoods.

Les terrasses fluviatiles quaternaires de la Somme à Abbeville : 150 ans de recherches mêlant géologie et archéologie, de Boucher de Perthes à aujourd’hui

Paleolithic localities associated with fossil fluvial formations of the Somme River at Abbeville have played a significant role in the recognition of human antiquity. From the end of the 18th century, the work carried out in particular by the “Société d’émulation d’Abbeville” led to the emergence of studies in the Somme valley on both Quaternary Geology and Prehistory. It was within this scholarly society that Jacques Boucher de Perthes initiated his research on the famous localities of Menchecourt, Hospital and Moulin Quignon in 1837. These observations were quickly confirmed by geologists such as Albert Gaudry, Charles-Joseph Buteux or Joseph Prestwich. It was the latter who introduced the Abbeville deposits into the United-Kingdom scientist community and his observations were used as early as 1859 by Charles Lyell to demonstrate the antiquity of the archaeological remains collected from these localities. However, the controversy surrounding by the discovery of the human jaw of Moulin Quignon (1863–1864), which undermined the credibility of this locality for a long time, led to the decrease of the archaeological researches in the Somme valley, and in particular in Abbeville, but it then resumed quite quickly. However, if the work carried out by Geoffroy d’Ault du Mesnil from 1875 to 1898 had the merit to reaffirm the archaeological importance of the Abbeville deposits and to reveal the complexity of their Quaternary records, the geographical and stratigraphic imprecision resulting from these rare publications, coupled with the gradual abandonment of the various gravel pits whose exploitation he followed, cast a significant discredit on these discoveries and on the stratigraphical observations he made there. The researches carried out then by Victor Commont at Carpentier Quarry between 1904 and 1918 were characterized by the excellence of the stratigraphic and iconographic data he produced for each of the studied sites. However the absence of archaeological discoveries in the fluvial deposits he studied lead the prehistorians who succeeded him increasingly doubted of the veracity of Ault's observations, despite the efforts made by Abbé Henri Breuil to reconcile these with Commont's observations. Between the two world wars, Breuil and Léon Aufrère resumed the study of the Abbeville deposits then still accessible, tried to ensure their preservation, through the purchase and protection of the Carpentier and Léon quarries, a decisive intervention in the archaeological rehabilitation of these deposits. These works were at the origin of the chronostratigraphic studies carried out on these major localities of the ancient European prehistory until today. Over the past ten years, some of these localities have been studied again, thus largely confirming the observations made by the elders (Boucher de Perthes, d’Ault du Mesnil, Commont) and validating the major place of Abbeville in the understanding of ancient prehistory settlement of northwestern Europe.

The geometry, sedimentary filling and depth estimate of the Mirandiba Basin, Pernambuco, Brazil: new insights about the depositional regional gap of rift phases in the interior basins

The Mirandiba Basin has a well-defined stratigraphic sequence and its sedimentation may be directly correlated with the Jatoba Basin and some other interior basins. The sedimentation began in intracratonic conditions with a Paleozoic sequence (Tacaratu/Inaja Formations), which acted as a substrate without any genetic relationship with the basin. The fluvial Tacaratu Formation emerges beyond the limits of this basin, where a remnant core named here as Poco do Ico was found wrapped around the basement to the west of the basin. Subsequently, there was a deposition in a shallow marine environment of the Inaja Formation (Devonian) formed by the intercalation of clay/siltstones and sandstones with ichnofossils. Pre-rift sedimentation occurs over the Paleozoic sequence, characterized in the basin by the lacustrine sediments of the Alianca Formation, represented by the intercalation of shales and calcarenites with desiccation cracks and fossil fragments. In spite of depositional gap described between the local Aratu and Alagoas Stages, the presence of Salvador Formation close to the north border fault may represent a rare rift phase record in the interior basins. The post-rift sequence is represented by the Marizal Formation, deposited during the Aptian. This formation is distinguished by the intercalation of fine sandstone, siltstone and conglomerate deposited in an alluvial fan environment. The pre-rift, rift and post-rift sedimentation are embedded in the depocenter of the basin, where the main NE-SWgraben stands out. A gravity survey was carried out, which obtained a negative, asymmetric Bouguer anomaly, with gradients added to the northwest, suggesting the existence of a half-graben. The result of the gravity 3D model indicates the existence of a main depocenter in the NE-SW direction with depths of up to 400 meters. These geophysical results support the tubular well location drilled 410 m in depth that was used in this work to better characterize the basin. The joint interpretation of gravity, aeromagnetic and structural data suggest that the half-graben framework of the basin developed by the evolution of a pull-apart extension system. The structural system that gave rise to the Mirandiba Basin has the maximum compression tensioner oriented to NE-SW and the distention to NW-SE. It has a depth of around 400 meters and the depressions formed by tectonic events were filled by Post-Tacaratu sedimentation.

Transgressive Pleistocene Cycles and Their Place on the Milankovich Scale

The problem of cyclic organization of geological environment in the Pleistocene is specified based on of materials on absolute chronology of marine and intracontinental sediments of North and Central Asia and North America. New data on absolute chronology of fluvial transgressive-regressive cycles of the Pleistocene in comparison with the known solar climate scale of M. Milankovich’s are given. It is established that the two most ancient dates of the terrace sediments of the Lena River (234 and 182 thousand years ago) and the Vilyuy River (300 and 176 thousand years ago), as well as three groups of dates of younger Late Pleistocene and Holocene fluvial formations in the valley of the Lena River, Rocky Mountains and in the Primorsky Lowland of the Laptev Sea (36 - 42.8; 27-29 and 8-10 thousand years ago) correlate with the M. Milankovic’s curve, describing the variability of the Earth’s solar climate with the period of about 41000 years. The oldest dates - 300 and 234 thousand years ago, and the date series in the chronological range 27-29 thousand years ago (five dates) coincide with the cold extremums of the M. Milankovic scale. Dates of 182 and 176 thousand years ago, as well as series of the dates in the range 36-42 thousand years ago (four dates) and 8-10 thousand years ago (3 dates) tend to warm extremums of the same scale.

ПОЛЕВЫЕ ИССЛЕДОВАНИЯ ОТСТУПАНИЯ БЕРЕГОВ РУСЛА Р. ОКИ В 2014–2018 ГГ. С ПОМОЩЬЮ МЕТОДА ПРОСТЫХ РЕПЕРОВ

In 2014–2018, within the middle part of the Oka River basin, on narrowed and widened sections of its floodplain, were conducted studies of the retreat rate of the channel steep banks. The method of erosional pins was used to determine the rate of changes in the floodplain edge contours on active bank slopes – sections of the relatively straight and meandering Oka channel. We established that in 2014–2017, with low floods, at the level of the lower and middle intervals of channel-forming discharges, lateral erosion was determined not so much by fluvial relief formation as by slope and anthropogenic processes. After the recession of the 2018 flood, which was close in its level and discharge to the average annual values, there was a significant intensification of the bank retreat under the direct influence of the flow and more frequent formation of hollows. The annual data and integrated research results over the five-year period indicate a significant predominance of longitudinal horizontal channel deformations and a slowdown in the rate of transverse deformations, especially in dry years. The significant role of the anthropogenic and slope components in lateral erosion of the Oka channel banks has been established.

Upper Jurassic dinosaur tracks from the Tianchihe Formation of Shanxi Province, China: review and new observations

ABSTRACT A sauropod track assemblage from a surface in the Upper Jurassic fluvial Tianchihe Formation at the Guanxi site, Shanxi Province, China, is re-documented and analysed in detail, together with a recently discovered new locality situated nearby. In contrast to earlier reports, the former includes four trackways plus isolated tracks (41 tracks in total) instead of five trackways (37 tracks in total) identified earlier, with pes prints reaching more than 60 cm in length. The new site has three pes-manus track pairs belonging to smaller individuals, with pes prints being about 20 cm in length. The absence of larger sized tracks at this locality suggests the possible presence of size-differentiated groups representing juveniles or subadults. Track morphology, heteropody and the medium-wide gauge trackway pattern at both sites support an assignment to the ichnogenus Brontopodus. Trackmakers were eusauropods, possibly mamenchisaurids or more advanced forms such as macronarians. Results of re-investigation allow a new interpretation of trackway orientations and trackmaker behaviour, respectively, as well as a calculation of progression speeds that suggest walking movement.

Tufa Deposition Dynamics in a Freshwater Karstic Stream Influenced by Warm Springs

Sweet Springs Creek, located in the Valley and Ridge Province of the Appalachian Mountains in southeastern West Virginia and southwestern Virginia, USA, contains major fluvial tufa formations at the sites of localized fractures and faults. Sweet Springs Creek receives input from higher-temperature thermal springs of lower pH and higher sulfate concentration that differ significantly in chemical composition due to differences in the underlying geology. In this study, theoretical rates of tufa accumulation were compared with those measured on travertine tiles left in situ for 30 days during periods of high and low stream flow above and below the sites of major fluvial tufa formations. Consistent with the chemistry of the spring waters, observed and predicted tufa accumulation rates in the stream were low compared to others reported worldwide. Tufa formation rate estimates were consistently higher during seasonal conditions of low flow, warm temperatures, and higher pH that occurred in late summer, but net annual accumulation may still be zero or less due to formation erosion during periodic flooding events. Computer tomography analysis determined that the natural porosity of travertine tiles results in a total surface area 32% greater than that calculated based solely on tile dimensions, which may overestimate initial tufa accumulation rates in situ. Measured rates of carbonate deposition on travertine tiles were 1.6–82 × lower than rates predicted based on theoretical models, consistent with the hypothesis of rate reduction due to variable diffusional boundary layer limitations and variability in stream hydrology. The generation of loose, platy, and unconsolidated precipitate on tiles under geochemical conditions predicted to be the greatest for optimal tufa formation suggested that the precipitation of particulate calcite in the stream system may predominantly result in the formation of unconsolidated marl deposits.

Model calibration and optimization of a post-combustion CO2 WAG pilot in a mature oil field

A carbon dioxide (CO2) water-alternating-gas (WAG) pilot was conducted to gain insights into tertiary oil recovery potential via CO2 flood in the West Ranch Field as part of the Petra Nova project, the world's largest post-combustion CO2 capture and utilization initiative. With a fluvial formation geology, this is a challenging and novel application of CO2 enhanced oil recovery. The aim of this study is two-fold. First, to build a predictive dynamic model that incorporates the data acquired during the pilot operation. Second, to utilize this model to provide guidance for optimal design for a field-wide CO2 EOR operation.This study began with an initialization of the pilot sector model extracted from a calibrated full-field model. The pilot model calibration follows a two-step hierarchical workflow. First, we performed a large-scale update of the permeability distribution by integrating available bottomhole pressure and multiphase production data. Next, local permeability field is fine-tuned using a streamline-based method to match CO2 breakthrough times at the producers. The predictive capability of the calibrated model was verified through two blind validation tests: (1) the model showed good agreement with saturation logs acquired at two observation wells; and (2) the model reproduced the CO2 recovery as a fraction of the injected CO2.Sensitivity studies were conducted using the calibrated pilot model to evaluate the effects of various operational parameters. Finally, we performed a Design of Experiment based multi-objective optimization of the CO2 WAG processes using the influential operational parameters identified from the sensitivity analysis.

Post-Combustion Carbon Dioxide Enhanced-Oil-Recovery Development in a Mature Oil Field: Model Calibration Using a Hierarchical Approach

SummaryWe present a simulation study of a mature reservoir for carbon dioxide (CO2) enhanced-oil-recovery (EOR) development. This project is currently recognized as the world's largest project using post-combustion CO2 from power-generation flue gases. With a fluvial formation geology and sharp hydraulic-conductivity contrasts, this is a challenging and novel application of CO2 EOR. The objective of this study is to obtain a reliable predictive reservoir model by integrating multidecadal production data at different temporal resolutions into the available geologic model. This will be useful for understanding flow units along with heterogeneity features and their effect on subsurface flow mechanisms, to guide the optimization of the injection scheme and maximize CO2 sweep and oil recovery from the reservoir.Our strategy consists of a hierarchical approach for geologic-model calibration incorporating available pressure and multiphase production data. The model calibration is performed using regional multipliers, and the regions are defined using a novel adjacency-based transform accounting for the underlying geologic heterogeneity. The genetic algorithm (GA) is first used to match 70-year pressure and cumulative production by adjusting pore volume (PV) and aquifer strength. Water-injection data for reservoir pressurization before CO2 injection is then integrated into the model to calibrate the formation permeability. The fine-scale permeability distribution consisting of more than 7 million cells is reparameterized using a set of linear-basis functions defined by a spectral decomposition of the grid-connectivity matrix (Laplacian grid). The parameterization represents the permeability distribution using a few basis-function coefficients that are then updated during history matching. This leads to an efficient and robust work flow for field-scale history matching.The history-matched model provided important information about reservoir volumes, flow zones, and aquifer support that led to additional insight compared with previous geological and simulation studies. The history-matched field-scale model is used to define and initialize a detailed fine-scale model for a CO2 pilot area that will be used to study the effect of fine-scale heterogeneity on CO2 sweep and oil recovery. The uniqueness of this work is the application of a novel geologic-model parameterization and history-matching work flow for modeling of a mature oil field with decades of production history, and which is currently being developed with CO2 EOR.

Fluvial responses to the Weichselian ice sheet advances and retreats: implications for understanding river paleohydrology and pattern changes in Central Poland

The evolution of the fluvial systems during the Weichselian Pleniglacial in the Toruń Basin (Central Poland) was investigated through sedimentological investigation and paleohydraulic analysis. Within the basin, three fluvial cycles deposited after successive phases of the ice advance which took place 50, 28 and 20 ka ago. Successions of four fluvial lithotypes characterize each fluvial formation, that are related to the paleoenvironmental changes (e.g., climate instability and changes in the river regime) which affected the channel hydraulics and morphology. The successions comprise river-style metamorphosis between high-energy sand-bed meandering rivers (lithotype M1), high-energy sand-bed braided rivers (lithotype B1), and medium-energy sand-bed braided rivers with either unit bars (lithotype B2) or compound bars (lithotype B3) reflects the maturity stage of sand-bed-braided river evolution in the basin. The assessment of the fluvial sedimentary environments enabled the construction of a quantitative model of the changes in the river channel pattern in relation to the climate oscillation. Both the paleohydrological controls and their sedimentary consequences are discussed in the article. Lithotypes M1 and B1 represent riverbed modeled under supercritical flow condition. Deposition of lithotype B2 corresponded to the river channel pattern transformation and was manifested by decreasing flow velocity (energy losses associated with bedform roughness and with the transportation of coarser particles). The flow velocity was generally greater in rivers of lithotype B3 and energy of sedimentary environment was more stable than during the deposition of lithotype B2.

Linking Holocene hydrologic events with episodic periods of fluvial deposition and soil formation, Santa Catalina Island, California

Linking Holocene hydrologic events with episodic periods of fluvial deposition and soil formation, Santa Catalina Island, California

MAKKAVEYEV'S DOCTRINE OF SINGLE EROSION-ACCUMULATIVE PROCESS AND THEORY OF EROSION-CHANNEL SYSTEMS

The creation conditions of single erosion-accumulative process doctrine and its development by N.I. Makkaveyev as well as its role in understanding of fluvial relief formation logic are analyzed. The paper describes the main laws concerning the effect of run-off on Earth surface. The evolution of doctrine led to the development of erosion-channel systems' theory. The structure of such systems is given; the connections of their elements with the water and silt load flow direction are described.

New stratigraphic and geochemical data on the Holocene environment and climate from a tufa deposit at Direndall (Mamer Valley, Luxembourg)

Tufa deposits are proven to record high quality palaeoenvironmental and palaeoclimatic information. They also appear to be influenced by human activities as indicated by the ‘late Holocene tufa decline’ observed in Europe from the Atlantic optimum, when tufa should be well developed regarding climatic conditions. The studied tufa comes from the Mamer Valley in Luxembourg: Direndall. As it covers a broad part of the Holocene, this deposit offered a great opportunity to discuss modalities and timing of the tufa decline and the human impact on fluvial formations since the early Holocene. Recent fieldwork at Direndall allowed the collection of new stratigraphic data and samples for a geochemical study. We investigate calcite stable isotopes as records of past temperature and humidity conditions. Comparisons with the environmental reconstructions from a previous malacological study show strong consistency with the δ13C record and suggest humidity might have been the main factor controlling environment evolution at Direndall. Despite the climatic variations observed, none explains the environmental change towards open conditions while optimum forest develops as recorded by molluscs at the top of the sequence. This episode is likely to be linked to local anthropogenic forest clearance during the Roman occupation. However, no clear impact of human activity has been observed in the tufa stratigraphy or precipitation rate. The exceptionally long Direndall tufa sequence thus provided outstanding palaeoenvironmental and palaeoclimatic data and might become, together with the underlying fluvial and colluvial deposits, a reference site for the Holocene and Tardiglacial in Luxembourg and surrounding areas.

Geochemical impact of aquifer storage for impure CO 2 containing O 2 and N 2 : Tongliao field experiment

• An aquifer storage of impure CO 2 containing N 2 and O 2 was studied with geochemical monitoring. • Chemical reactions are clearly pH and redox sensitive. • O 2 enhances the remobilization of certain minerals in the aquifer formation. • The migrations of geochemical components are very complex in fluvial formation. • Chromatographic partitioning processes of chemical components occur in both aqueous and gaseous phases. Impurities such as N 2 and O 2 can be co-injected with CO 2 to cut the overall cost of carbon capture and geological storage by lowering the CO 2 capture cost. However, only few field-scale studies have focused on the effect of these impurities, such as N 2 and O 2 , with low solubility and a low reaction rate in a CO 2 stream. A pilot-scale experiment on impure CO 2 aquifer storage containing N 2 and O 2 was conducted in Tongliao, Inner Mongolia, China, where 200 tonnes of CO 2 and 30 tonnes of air were injected into the upper Yaojia Formation. The geochemical characteristics of flow-back formation fluid in three monitoring wells were investigated by using a U-tube-based sampling system. The following conclusions can be drawn from the preliminary geochemistry analysis: (1) The underground chemical reactions in the CO 2 and air co-injection process are clearly pH and redox sensitive, which is in contrast with pure CO 2 aquifer storage. Oxygen enhances the remobilization of certain minerals in the aquifer formation and provides new reactive tracers such as uranium and SO 4 2− . (2) The migration pattern of the formation fluid and the geochemical components in the fluid are very complex, particularly when the reservoir exhibits high heterogeneities of geology, mineralogy, and groundwater chemistry. (3) Chromatographic partitioning processes of chemical components occur in both aqueous and gaseous phases. In the aqueous phase, the dissolved O 2 and CO 2 arrive at the monitoring wells earlier than they do in the gaseous plume. The CO 2 -induced ions arrive at the monitoring wells earlier than the O 2 -induced ions; however, the dissolved O 2 arrives earlier than the dissolved CO 2 . The N 2 and O 2 in the gas mixture arrive at the monitoring wells earlier than CO 2 and form the migration front of the underground gas stream. This study provides a new dataset for evaluating possible scenarios of underground migration behavior and metal remobilization in response to the co-injection of CO 2 with O 2 , and N 2 .