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The results of regional studies of Early Miocene deposits in Western Ciscaucasia, based on the seismic stratigraphic analysis, are presented. The spatial pattern of sediment accumulation is analyzed and the paleogeographic conditions during the Late Miocene regressive stages in Western Ciscaucasia are refined. Erosional incisions of several levels, developed during the base-level fall in the course of major regressions in the studied time interval, were identified. Based on the spatial correlation of paleoincisions using a chosen series of intersecting seismic profiles, the buried Paleo-Don and Paleo-Donets river valleys were reconstructed at the Sarmatian‒Meotian boundaries and within the Meotian‒upper Pontian interval. [ABSTRACT FROM AUTHOR]

Effective site characterization in highly urbanized coastal lowlands requires accurate stratigraphic and geophysical investigations. In these regions, which typically host shallowly buried paleovalley systems formed in response to Quaternary glacio‐eustatic fluctuations, the marked lithologic contrast between soft sediment paleovalley fills and the adjacent, stiff substrate has the potential to modify earthquake motions, and assessment of critical parameters, such as shear wave velocities (VS) and resonance frequencies (f), should be coupled with detailed stratigraphic architecture. To evaluate the potential of the microtremor horizontal‐to‐vertical spectral ratio (mHVSR) for paleovalley recognition and mapping, we performed mHVSR measurements along the Adriatic coastal plain of Italy, where two paleovalley systems (Pescara and Manfredonia) have been recently identified. In both areas, we detected rapid lateral variations in resonance frequencies and highlighted laterally continuous impedance contrasts. Relying on a robust stratigraphic framework, we carefully evaluated the relation between geological and geophysical data and identified the stratigraphic surfaces responsible for the observed resonances. We derived VS models for the sediment fill, reconstructing the geometry of the two buried paleovalleys. We address the importance of evaluating the geological context when designing microzonation studies, for a reliable interpretation of changes in resonance frequencies. Plain Language Summary: When earthquakes occur, buildings shake differently based on several factors, including seismic wave velocity, natural resonance frequencies, and local geological characteristics. Beneath modern coastal lowlands, the presence of paleovalley systems can significantly modify the ground motion. Identification of these buried bodies is therefore essential to assess and reduce seismic hazard. Paleovalleys are shallow incisions formed under periods of fluvial erosion in response to Quaternary climate fluctuations, and subsequently filled with very soft clay. These bodies are found worldwide, and do not have any geomorphological evidence, making their recognition challenging. Geologists typically use expensive sediment core analysis to identify paleovalleys, but this method can only provide spotty information. Geophysical exploration techniques that rely on microtremors (small vibrations on the Earth) can complement mapping of these buried bodies. In this work, we tested this technique in Pescara and Mafredonia (Adriatic coastal plain, Italy), providing dense information about paleovalley geometries and geophysical parameters crucial for predicting how the ground will shake during an earthquake. This study also highlights the importance of integrating disciplines to improve our understanding of subsoil and to design future studies to mitigate seismic hazards. Key Points: Paleovalley fills are key sediment bodies made up of soft clay, tens of m thick and few km wide, buried beneath coastal lowlands worldwideMicrotremor‐based paleovalley profiles and stratigraphic cross‐sections exhibit strong similarityMicrotremor can provide shear wave velocities and resonance frequencies of paleovalleys, key parameters for seismic hazard mitigation [ABSTRACT FROM AUTHOR]

Abstract Effective site characterization in highly urbanized coastal lowlands requires accurate stratigraphic and geophysical investigations. In these regions, which typically host shallowly buried paleovalley systems formed in response to Quaternary glacio‐eustatic fluctuations, the marked lithologic contrast between soft sediment paleovalley fills and the adjacent, stiff substrate has the potential to modify earthquake motions, and assessment of critical parameters, such as shear wave velocities (VS) and resonance frequencies (f), should be coupled with detailed stratigraphic architecture. To evaluate the potential of the microtremor horizontal‐to‐vertical spectral ratio (mHVSR) for paleovalley recognition and mapping, we performed mHVSR measurements along the Adriatic coastal plain of Italy, where two paleovalley systems (Pescara and Manfredonia) have been recently identified. In both areas, we detected rapid lateral variations in resonance frequencies and highlighted laterally continuous impedance contrasts. Relying on a robust stratigraphic framework, we carefully evaluated the relation between geological and geophysical data and identified the stratigraphic surfaces responsible for the observed resonances. We derived VS models for the sediment fill, reconstructing the geometry of the two buried paleovalleys. We address the importance of evaluating the geological context when designing microzonation studies, for a reliable interpretation of changes in resonance frequencies.

Buried river valleys from the Neogene–Quaternary time are widespread throughout the Middle Volga region of the Russian Plain. They have been studied for a long period, since the 1940s, with the last major generalizations dating back to the 1980s. This paper presents new results based on GIS mapping using materials from the state geological study of the region in 1960–1970, 1984–1996 and 2000–2002. On the whole, the pattern of the buried valley network is close to the modern valley network of the region. During the Quaternary, the right-sided displacement of the valley incisions prevailed. The incisions of modern river valleys are located above the Neogene (pre-Akchagyl) incisions almost throughout the entire territory. The vertical displacement amplitude ranges from 30 to 200 m. The morphometric characteristics of the paleovalleys (the depth and width of the incisions, as well as the gradients of the bottoms of the paleovalleys) exceeded modern ones. The maximum values were typical for the middle Paleo-Volga valley: the width of the valley reached 10 km, the incision depth was−201.4 m below sea level and the bottom gradient was 0.9–5.0 m/km. The most important factor that influenced the position of paleovalleys and their morphological appearance was fluctuations in the level of the Caspian paleowaterbody. According to this study, the development of paleovalleys began in the Miocene and ended in the Early Quaternary. The alluvial–lacustrine type of sedimentation was predominant. The results of this work contribute to the study of the paleogeography of the Cenozoic of the southeast of the Russian Plain. [ABSTRACT FROM AUTHOR]

Mollusk fauna is an important component of the Caspian Sea ecosystem alongside ostracods and diatoms. These faunal proxies are essential indicators of hydrological shifts reflecting global and regional climate changes. Adding lithological, geochemical, and geochronological (radiocarbon) data, we revealed paleogeographic events of different scales recorded in the sequence of the Rybachya core from the North Caspian Sea. Here, we present the reconstruction of Mangyshlak paleovalley sediments during the Holocene multi-stage Neocaspian transgression, reflecting global and regional climate changes varying in scale and direction. The determined age of paleovalley-fill sediments, 8070 ± 110 cal yr BP and 7020 ± 140 cal yr BP, suggests that sedimentation processes with extended warming and humidification started later and lasted longer than was assumed earlier. Biological proxies indicate quasi-cyclic variability and shifts from brackish to freshwater conditions throughout the studied interval. Rybachya core was obtained from the early Khvalynian deposits. The Mangyshlak flow formed the depression and eroded the late Khvalynian deposits, which we did not observe in the core structure. It possibly collapsed into paleodepression and acted as a host material for the freshwater lentic faunal association. During the Holocene, we detected a transition from a tranquil water regime to a more dynamic one during the paleovalley gradual filling, followed by marine conditions typical for the modern Caspian Sea. [ABSTRACT FROM AUTHOR]

Robust site characterization and ground response analysis require a thorough understanding of subsurface features, including geophysical properties and geometries of sediment bodies. Late Quaternary paleovalley systems, often overlooked in seismic hazard assessments, represent a potential threat due to their unconsolidated infill (with shear wave velocities <200 m/s) and sharp contrast with the adjacent substrate. Through an integrated approach that combined geophysical and stratigraphic data, we characterized the subsurface of the Pescara paleovalley system. Geostatistical interpolation of microtremor measurements enabled mapping resonance frequencies, highlighting abrupt changes and delineating the paleovalley boundaries. High-resolution core descriptions were then correlated with resonance frequencies, enabling the reconstruction of a 3D geophysical depth model of the buried paleovalley morphology. Furthermore, analyzing velocity profiles from down-hole tests led to the identification of five main seismic/stratigraphic layers within the valley fill. The geometry and facies architecture were reconstructed through a cross-section transversal to the paleovalley axis and then implemented into a 2D finite element model. Seismic response was computed, revealing significant amplification factors at frequencies closely matching the direct observations. Amplification factors peaked at frequencies between 0.9 and 1.1 Hz in the paleovalley center and up to 5.5 Hz towards the flanks, reaching a factor of 4.6. These findings suggest a notable increase in amplification amplitude compared to simpler geological contexts and emphasize the potential impact on common building types. Response spectra show strong amplifications in the paleovalley system, potentially leading to an underestimation of spectral accelerations compared to NTC18 guidelines. The comparisons of 1D and 2D modeling approaches revealed minimal differences, indicating that the generally flat geometry of the valley may not exhibit clear 2D effects. However, local subsurface stratigraphy strongly influences lateral changes in seismic response, emphasizing the importance of detailed subsurface knowledge for realistic seismic response estimates. • Mapping Resonance frequencies allowed 3D characterization of buried morphologies. • Late Quaternary paleovalley systems are associated with elevated seismic hazzard. • Paleovalley systems exhibit high seismic amplification. • This study challenges Eurocode 8 and NTC18 guidelines. • Subsurface stratigraphy is crucial for estimating lateral changes in seismic response. [ABSTRACT FROM AUTHOR]

The Ingul megablock of the Ukrainian Shield contains a number of endogenous deposits of the sodium-uranium formation, which have been developed for more than 55-60 years. With the exception of the Kirovograd uranium ore region, the deposits of which are controlled by discontinuities in the fault zone of the same name, the Vatutinske and Novokostiantynivske ore fields occupy positions within the Novoukrainsky granite-gneiss dome and in close proximity to the later geostructural formation, the Korsun-Novomyrgorod pluton. Paying attention to the high degree of saturation of the Ingul megablock with endogenous uranium deposits, it is emphasized that they also contain an increased content of thorium minerals and, in combination with uranium, they produce ascending gas flows of radon. Therefore, studies of the dynamics of the upper horizons of the lithosphere and the closely related dynamics of the hydrosphere (underground and surface), as well as the gas sphere, are especially relevant both in the regions of uranium ore fields and in areas adjacent to mining enterprises. Beyond the direct influence on the radioecological situation of uranium mining enterprises, special attention should be paid to the study of the dynamics of the lithospheric surface, including fault-block structures and the kinematics of ruptures, affecting the spread of groundwater and, as a result, surface waters contaminated with uranium in the environment. In the areas of uranium ore fields, the kinematic characteristics of disjunctivals contribute to a more correct forecast of radon accumulation in natural weakly insulated underground decompressed structures and the accumulation of more long-lived products of its decay Po, Bi, and Pb with long periods of removal of biological objects from organisms. It is emphasized that in the mine workings of mining enterprises, the technological process is accompanied by nitrate pollution of groundwater due to the use of nitrate-based explosives. Thus, for the predictive assessment of radiation and nitrate pollution of the environment of industrial sites of mining enterprises and adjacent territories, the technological process of which also affects the dynamics of the litho-hydro- and gas sphere, the structural-geological, paleogeomorphological, lithological, hydrogeological, hydrographic and topographic features of the Vatutinske and Novokostiantynivske uranium ore fields. The directions of the advancement of the groundwater fronts from directly uranium mines to the nearest drains have been established. The levels of uranium pollution of surface and underground (well) waters within the Novokostiantynivske uranium ore field, as the most promising for increasing uranium mining in the coming decades, have been determined. The proposed areas and terms of complex radioecological monitoring of the Novokostiantynivske uranium ore field in order to take preventive measures to prevent the withdrawal of existing local recreational areas and water areas into the category of ecologically hazardous. On the example of the Novokostiantynivske uranium deposit, as one of the richest endogenous deposits in Ukraine, through the production shafts, which is planned to rise to the surface of uranium ore from the same type of deposits of the uranium ore field of the same name (Lisne, Litniy and Dokuchaivske) by transporting it by main drifts, the proposed optimal complex of geodynamic studies in the system of radio and general ecological monitoring of the state of the environment of such territories.

The ferricrete units (Fe oxide cemented colluvial-alluvial sediment) of the Yilgarn Craton in Western Australia formed during the humid tropical and sub-tropical climates of the Cenozoic. Ferricretes are generally developed on long-lived paleodrainage systems and are products of the ferruginisation of detritus provided by the continuous erosion of upslopes. These iron-rich accumulations can become Au-enriched, as is the case in several locations previously discovered in the Yilgarn Craton; many of these host economic secondary gold deposits (e.g., Moolart Well, Mt Gibson, and Bulchina), typically occurring downslope of low saprolite hills and near paleovalleys (i.e., inset-valleys). Inset-valleys are a common paleotopographic feature buried under Quaternary alluvial and colluvial sedimentary cover. Maps of these ancient channel networks can be used as a proxy for targeting ferricrete gold deposits. These inset-valley systems generally form dendritic and noisy patterns in high-resolution aeromagnetic data due to the presence of maghemite-rich nodules and detrital magnetic pisoliths on their flanks. The main aim of this study was to use high-resolution aeromagnetic data to target ferricrete units related to inset-valleys systems across the Yilgarn Craton. A spatial predictive model was used to learn and predict the geological units of interest from pre-processed aeromagnetic data. The predicted inset-valleys systems were able to confine the exploration space and define a new exploration frontier for ferricrete gold deposits. [ABSTRACT FROM AUTHOR]

Buried river valleys from the Neogene–Quaternary time are widespread throughout the Middle Volga region of the Russian Plain. They have been studied for a long period, since the 1940s, with the last major generalizations dating back to the 1980s. This paper presents new results based on GIS mapping using materials from the state geological study of the region in 1960–1970, 1984–1996 and 2000–2002. On the whole, the pattern of the buried valley network is close to the modern valley network of the region. During the Quaternary, the right-sided displacement of the valley incisions prevailed. The incisions of modern river valleys are located above the Neogene (pre-Akchagyl) incisions almost throughout the entire territory. The vertical displacement amplitude ranges from 30 to 200 m. The morphometric characteristics of the paleovalleys (the depth and width of the incisions, as well as the gradients of the bottoms of the paleovalleys) exceeded modern ones. The maximum values were typical for the middle Paleo-Volga valley: the width of the valley reached 10 km, the incision depth was−201.4 m below sea level and the bottom gradient was 0.9–5.0 m/km. The most important factor that influenced the position of paleovalleys and their morphological appearance was fluctuations in the level of the Caspian paleowaterbody. According to this study, the development of paleovalleys began in the Miocene and ended in the Early Quaternary. The alluvial–lacustrine type of sedimentation was predominant. The results of this work contribute to the study of the paleogeography of the Cenozoic of the southeast of the Russian Plain.

Mollusk fauna is an important component of the Caspian Sea ecosystem alongside ostracods and diatoms. These faunal proxies are essential indicators of hydrological shifts reflecting global and regional climate changes. Adding lithological, geochemical, and geochronological (radiocarbon) data, we revealed paleogeographic events of different scales recorded in the sequence of the Rybachya core from the North Caspian Sea. Here, we present the reconstruction of Mangyshlak paleovalley sediments during the Holocene multi-stage Neocaspian transgression, reflecting global and regional climate changes varying in scale and direction. The determined age of paleovalley-fill sediments, 8070 ± 110 cal yr BP and 7020 ± 140 cal yr BP, suggests that sedimentation processes with extended warming and humidification started later and lasted longer than was assumed earlier. Biological proxies indicate quasi-cyclic variability and shifts from brackish to freshwater conditions throughout the studied interval. Rybachya core was obtained from the early Khvalynian deposits. The Mangyshlak flow formed the depression and eroded the late Khvalynian deposits, which we did not observe in the core structure. It possibly collapsed into paleodepression and acted as a host material for the freshwater lentic faunal association. During the Holocene, we detected a transition from a tranquil water regime to a more dynamic one during the paleovalley gradual filling, followed by marine conditions typical for the modern Caspian Sea.

Natural graphite, a polygenic mineral, is a product of regional, contact, impact metamorphism, and magmatic or fluid deposition. In fluid-deposited graphite, aqueous C-O-H systems play a special role in determining the characteristics of hydrothermal products by shifting the chemical equilibrium. From this viewpoint, the recently discovered carboniferous mineralization in the Baikal hydrothermalites has attracted increasing interest with regard to graphite crystallization under the influence of low-pressure low-temperature (LPLT) carboniferous H2O-rich fluids. Herein, we studied graphite mineralization in the geyserites and travertines of the Baikal geyserite paleovalley (Eastern Siberia, Russia) by applying a multitude of mineralogical studies. Optical, scanning, transmission electron, and atomic force microscopy, energy-dispersive spectroscopy, Raman spectroscopy, and carbon isotopic composition analyses of graphite, carbonate carbon, and oxygen in both the hydrothermalites and host rocks were conducted. The obtained results revealed several peculiar features regarding the graphite in geyserites and travertines. We found that Baikal graphite, earlier predicted to be a product of hydrothermalites, generally occurs as a relict graphite of the host metamorphic rocks with partial in situ redeposition. The newly formed LPLT fluid-deposited graphite is characterized by micrometer- and submicrometer-sized idiomorphic crystallites overgrown on the relict metamorphic graphite seeds and between calcite sinter zones during the last stage of travertine formation. The results present additional valuable data for understanding the mechanism, range of the formation conditions, and typomorphism of fluid-deposited graphite with probable crystallization from carbon solution in the C-O-H system at LPLT conditions. [ABSTRACT FROM AUTHOR]

Alterations, such as drainage network reorganization, in the landscape in the Amazon basin influence the distribution range and connectivity of aquatic biota and, therefore, their evolution. River capture is a geomorphic mechanism of network reorganization by which a basin captures large portions of the network of a neighboring basin, thus creating a barrier against species dispersal. In this study, the influence of river capture on the genetic differentiation and structuring of two dwarf cichlids species (Apistogramma pertensis and Apistogramma gephyra) is investigated in two tributaries of the lower Negro River. The analysis of 11 loci microsatellite and three mitochondrial DNA genes (Cytochrome b, Citochrome c Oxidase subunit I and 16S ribosomal RNA) confirmed the populational isolation of two dwarf cichlids species, suggesting that they represent evolutionary significant units (ESU) that have been isolated—probably due to the river capture event. The paleovalley that resulted from the river capture is therefore an important physical barrier that separates the populations of the Cuieiras and Tarumã-Mirim Rivers. The findings herein provide evidence of a mechanistic link between the isolation and differentiation of fish populations and the drainage evolution of the Amazon basin, and indicate that the dynamic geological history of the region has promoted species diversification. The process described here partially explains the high diversity in the genus Apistogramma and the information obtained is beneficial to conservation programs.

The paper reports geochemical and mineralogical data on ores of the Briketno-Zheltuhinskoe U–Mo–Re deposit, which is confined to the Visean paleochannel coal-bearing sandy sediments of the Moscow lignite basin. In addition to main ore elements (Re, Mo, U, and Se), the ores have elevated contents of the following metals (in order of decreasing abundance): Zr, Zn, Mn, Ni, As, Co, V, Pb, Y, Cu, and highly dispersed Tl and Ag. It was found that Re correlates positively with Mo, Ag, Zn, U, Se, and Co. The ores are incoherent and analytical scanning electron microscopy is the main method applied for their study. In order to clarify the speciation of U, Mo, and Re, sequential extraction experiments were performed. The main part of Re is associated with the organic and ion-exchange forms. Molybdenum is approximately equally distributed between the strongly bound (sulfide) and organic-related forms. Uranium mainly occurs in a weakly bound form and easily migrates with water. Authigenic minerals are mainly represented by pyrite, less common marcasite, and accessory sulfides (sphalerite, chalcopyrite, galena, etc.) and selenides (dzharkenite, clausthalite). Mo-minerals (containing up to 1.5 wt % Re) are represented by the tiny grains of molybdenite and jordisite. Uranium occurs as micron-size inclusions of uraninite (pitchblende) in colloform pyrite and is present as a macro-impurity in rhabdophane and zircon. The predominant part of U, Mo, and Re was found in adsorbed forms in carbonaceous, clayey, and strongly altered sulfide particles. Arkose and subordinate ash material together with heavy metals (Fe, Ni, Cu, Zn, Pb, U, Mo, Re), and also S and Se, were transported by river streams and accumulated in terrigenous sediments of shallow marine basin. These elements were adsorbed by plant detritus and, partly, by clay particles and iron oxyhydroxides/sulfides during diagenesis. The main economic U–Mo–Re ores were formed at the second, epigenetic stage, in the course of the lateral filtration of oxygenated groundwater through highly permeable sand horizons. This process was accompanied by the redeposition of U, Mo, Re, Se, Cu, Ni, and Zn from dispersed mineralization of the first stage at the reducing (plant detritus) and sorption (clay sediments) geochemical barriers. In this case, U, Mo, and Re were fixed in the mineral and, mainly, adsorbed forms. Significant contribution to the ore formation was likely provided by endogenous factors associated with activation of faults in the East European Platform (EEP) basement, epiplatform alkaline-basaltic magmatism, and the influx of deep fluids into the ore deposition zone. [ABSTRACT FROM AUTHOR]

The Briketno-Zheltukhinskoe U–Mo–Re deposit is located in the southern sector of the Moscow lignite basin (central East European Platform). It is restricted to the paleochannel and deltaic coal-bearing sandy sediments of the Visean Bobrikov horizon lying on the Famennian limestone. They are overlain by the younger Neogene–Quaternary sands and clays. Tectonically, the deposit is ascribed to the southern shoulder of the Pachelma aulacogen crosscut by the SN-trending fault zone. The presence of a thick gray-colored unit of inequigranular moderately and poorly sorted sands containing the coalified plant detritus served as the main lithological-facies factor for the localization of U–Mo–Re mineralization. The Bobrikov sandy formation was accumulated in the fluvial, swampy, onshore deltaic, and shallow-sea lagoonal environments with warm humid climate. A combined syn-epigenetic model is proposed to explain the formation of the U–Mo–Re paleovalley-type deposit. Subeconomic stratabound U (±Mo, Re) mineralization associated with the carbonaceous and clayey horizons was accumulated during sedimentation and diagenesis. During epigenesis, the U–Mo–Re ores were deposited by oxidized groundwater owing to its lateral filtration through highly permeable sand horizons and metal accumulation at the reducing and sorption barriers. The general subhorizontal stratiform structure of the ore deposit is complicated by the subvertical morphological (swell of sand horizon plus strong pyritization) and concentration (Re + Mo column-like maximums) ore shoots. They occur in dome-like structures that disturb the horizontal structure of the host sedimentary unit. It is possible that these domes and ore shoots are the result of hydrothermal-hydraulic processes caused by the activity of deep crustal (likely, mantle as well with allowance for the Re mineralization) fluids. [ABSTRACT FROM AUTHOR]

This paper focuses on the relation between two significant geomorphic features of the western Taurides: the Antalya Tufa Plateau and the structural Kestel polje system; revealing morphotectonic records of the formation and evolution of karst hydrology between the two features. Data were obtained by detailed mapping of faults, rocks, and geomorphic features. The evolutionary history of the area begins with a nearly E-W-trending drainage system which flowed on the erosional surfaces formed during late Langhian-early Messinian under the compressional tectonic regime. The running waters comprising the major drainage system incised the valleys during the Messinian Salinity Crisis and partly in the Pliocene by over 200 m depth across the study area. From the beginning of the Quaternary, a tensional tectonic regime became prominent and a series of graben-horst structures were formed. The Kestel polje system, consisting of five sub-poljes, developed within the graben structures which emerged in the upper basin of rivers during this period, and the middle part of the river valleys were transformed into hanging valleys on the horsts. Thus, drainage of the Kestel polje system and horsts (mountainous area) that bordered the polje to the east was enabled through underground karst conduits. Consequently, CaCO 3 precipitating from waters coming out of the rich karst springs that fed the polje system and aquifers to the east formed the Antalya Tufa Plateau. • Kestel structural polje system was formed in Quaternary grabens. • Pliocene fluvial drainage system was disturbed and hanging valleys were formed. • Waters of the poljes were drained into Kırkgöz karst springs by underground conduits. • Antalya Tufa Plateau was formed by CaCO 3 precipitation of karst waters. • Karst hydrology in study area was affected by Quaternary tectonics. [ABSTRACT FROM AUTHOR]

Fjord systems, represented by glacial diamictites and postglacial transgressive shales, formed in the basins of western Argentina during the late Carboniferous Gondwana glaciation. Well exposed fjord deposits of the Guandacol Formation were studied in the Loma de Los Piojos region (Protoprecordillera), where they fill a 2.9 km wide paleovalley with steep side walls and a relatively flat floor. The valley cross-cuts Lower Devonian sandstones and Mississippian mudstones and sandstones, and provides evidence of glacial abrasion, including striated pavements and glacial microtopography (grooves, ridges, and striae). Based on the analysis of seven sedimentary logs, eight sedimentary facies in the valley fill were recognized: (A) Massive diamictites; (B) Laminated mudstones with dropstones; (C) Stratified diamictites; (D) Clast-supported conglomerates and sandstones; (E) Deformed diamictites, conglomerates and sandstones; (F) Folded diamictites; (G) Mudstones interbedded with sandstones, and (H) Stacked and amalgamated sandstones. These sedimentary facies are grouped into two principal facies assemblages that represent different stages of the paleovalley fill. Assemblage 1 is composed of diamictites (Facies A, C and F), laminated mudstones with dropstones (Facies B), and conglomerates (Facies D and E), which represent glacially influenced sedimentation in the paleovalley. Assemblage 2 represents the paleovalley fill when glacial influence ceased, and comprises laminated mudstones interbedded with sandstones (facies G) and stacked sandstone beds (facies H) that mostly record deltaic sedimentation. Stratigraphic relationships, plant fossils found in the paleovalley walls and palynological assemblages recovered in mudstones of facies D help to establish an early Pennsylvanian age for both the incision and the filling of the paleovalley. The studied paleovalley records an exceptional example of the western Gondwanan glacial to postglacial transition. Due to the continuous stratigraphic succession within the paleovalley as well as palynological, megafloristic and radiometric data, this example provides a complete framework of the late Carboniferous postglacial evolution in western Gondwana. [ABSTRACT FROM AUTHOR]

Both global and regional climate drivers contributed to glaciation during the late Paleozoic Ice Age (LPIA). However, the transition from icehouse to greenhouse conditions was asynchronous across Gondwana suggesting that, in some cases, regional controls played a significant role in deglaciation. Of particular interest to understanding changing LPIA climatic conditions, is the eastern Paganzo Basin. This region was flanked by ice centers in the Precordilleran and Sierras Pampeanas regions of Argentina on the west, and major ice sheets in the Paraná, Chaco-Paraná, and Sauce Grande basins to the east, all of which resided between ∼40 and 65° S latitude. Hypotheses on the occurrence of ice in the eastern Paganzo Basin are based on interpretations of the narrow, steep-walled, Olta-Malanzán paleovalley as carved by an alpine glacier or by an outlet glacier draining an eastern ice sheet, and that glaciers deposited coarse clastics within the paleovalley. However, we found no evidence for glaciation. Rather, gravel from prograding alluvial fans/fan deltas and rock falls ponded drainage resulting in lacustrine activity in the eastern end of the valley. A transition from either subaerially or shallow subaqueously deposited sandstones to marine mudstones in the western end of the Olta paleovalley suggest a marine transgression, which, in turn, was overlain by deposits of prograding Gilbert-type deltas. Dropstones were from rock falls off valley walls and rafting by lake ice rather than from icebergs. Therefore, we conclude that the climate in western Argentina resulted from uplift induced glaciation in the Precordilleran region and along the western margin of the Paganzo Basin, and the occurrence of a precipitation shadow to the east. The disappearance of the western glaciers during the mid-Carboniferous, prior to deglaciation elsewhere at the same paleolatitude, resulted from a westward shift in the position of the active margin, collapse of the glaciated upland(s), and an expansion of the precipitation shadow across the whole of western Argentina. [ABSTRACT FROM AUTHOR]

Detailed sedimentological and stratigraphic analysis of pre-vegetation sedimentary systems that deposited across global-scale climate change episodes is key to fully understanding past feedback responses in Earth surface systems and the details of their paleoenvironments. The Cobalt Basin, recording the upper Huronian Supergroup, captures a transition from glacial (Gowganda Formation) to post-glacial (Lorrain Formation) deposystems in parallel with Earth's Great Oxidation Event and is ideal for sedimentological/stratigraphic analysis due to its limited post-depositional deformation. Stratigraphic measurements and correlations from the northern Cobalt Basin reveal that the Gowganda and Lorrain formations are preserved within a paleovalley, interpreted as a fjord. Sub-glacial deposits of the Coleman Member (lower Gowganda Formation) are preserved at the base of the paleovalley, unconformably above Archean volcanic and granitic rocks of the Abitibi subprovince. Subsequently, the fjord was filled by glaciomarine strata sourced from a grounded tidewater icesheet prior to climate warming. Above the glaciomarine deposits, deltaic deposits of the Firstbrook Member (upper Gowganda Formation) represent a transition to nonglaciogenic deposition under a warm and humid climate. The deltaic deposits comprise three facies associations: (1) delta front/slope strata dominated by horizontally stratified siltstone; (2) interdistributary bay deposits composed of symmetrically rippled and thinly laminated siltstone; (3) distributary mouth bar deposits dominated by very fine-grained arenite. Delta front/slope deposits occur directly above glaciomarine strata, while interdistributary bay and distributary mouth bar deposits occur above delta front/slope strata and are laterally discontinuous across the study area. Prodelta deposits are not preserved in the study area, although they are reported elsewhere in the basin. At the flanks of the paleovalley, alluvial fan deposits, confined by Archean rocks, interfinger with deltaic strata. Alluvial fan sedimentation, triggered by enhanced weathering in an unvegetated warm and humid setting, led to flashy sheetflood deposition due to significant topographic variations at the flanks of the valley setting. In some instances, sandstone beds of the overlying Lorrain Formation, comparable to distal to medial reaches of the modern South Saskatchewan River, cut down through delta strata. Up-section, the braidplain strata coarsen to gravel-rich facies representing Donjek River-type deposits. Overall, the stratigraphic succession in the northern Cobalt basin study area represents a single progradation from glaciomarine through deltaic deposition, into fluvial braidplain deposition. The succession is preserved at the cratonward limit of a passive margin, suggesting that progradation was likely influenced by relative sea-level fall linked to glacio-isostatic uplift, similar to fjord-filled sedimentary successions that have developed since the Last (Pleistocene) Glacial Period. [ABSTRACT FROM AUTHOR]

This study analyzed the morphology of three late Pleistocene buried paleovalleys in the central Kanto Plain, Japan, by using data from sedimentary cores and boreholes. The paleo-Arakawa valley and the paleo-Nakagawa valley merge to form the paleo-Tokyo valley, which extends into Tokyo Bay. Although the last glacial sea-level fall controlled the formation of these paleovalleys, fluvial terraces developed differently in these paleovalleys, reflecting regional differences in tectonic activity. The paleo-Tokyo valley beneath the Tokyo Lowland, and the paleo-Arakawa valley beneath the Arakawa Lowland, are in relatively stable or uplifting regions, and both paleovalleys have several distinct fluvial terraces forming stepped cross-sectional profiles. In contrast, in the paleo-Nakagawa and the paleo-Arakawa valleys beneath the subsiding Menuma Lowland, terrace surfaces are obscure and there is a smooth gradient from the valley margins to the valley axis. The structure of the paleovalleys in the central Kanto Plain can thus be explained by the combination of eustatic sea-level fall and concurrent regional tectonic movement. [ABSTRACT FROM AUTHOR]

The features and similarities in the geology of paleovalley-related uranium mineralizing systems in Australia and China can be used to refine strategies for exploration. Paleovalley-related uranium resources include sandstone-, lignite- and calcrete-style deposits that are developed within the host sediments deposited in paleovalleys. The paleovalleys incise either crystalline bedrock or older sedimentary rocks, and uranium was deposited and concentrated by the influx of oxidized/reduced groundwaters flowing in aquifers within the paleovalley fill. The critical features of paleovalley-related uranium deposits include sediment and uranium sources, geological setting, depositional environment, age and relative timing of mineralization, aquifer characteristics, availability and distribution of reductants, and preservation potential of the uranium mineral system. This set of information provides a basis to establish the uranium mineralization model, which can then be used to assist with generating targets for uranium exploration and prospectivity analysis of a region. With respect to Sino-Australian examples, paleovalley-related uranium deposits form mostly around the margins of sedimentary basins and the mineralization is commonly hosted within channel fills contained within paleovalleys developed upon, or proximal to, Precambrian crystalline rocks that contain primary uranium sources. The deposits that have been well studied show remarkably similar factors that controlled the formation of paleovalley-related uranium deposits. Basement/bedrocks with above-background (2.8 ppm U) levels of uranium (10–100 ppm) that are linked to, and/or, incised by paleovalleys are associated with these deposits and are the inferred source of the uranium. In these regions, extensive fluvial systems developed particularly during Mesozoic and Cenozoic times, uranium from the bedrock was first dispersed into the sediments, and then concentrated to form deposits through successive chemical remobilization, precipitation and concentration. The deposits formed in continental or marginal marine environments, and commonly are associated with reduced lithologies, containing pyrite and dispersed organic matter and/or seams of lignite, or show evidence of infiltrated hydrocarbons. The mineralization is developed where oxidizing fluids (carrying dissolved U) reacted with reductants in the sediments. Geological, geophysical and geochemical features of the paleovalleys and related uranium deposits are used to construct models to understand host sediment distribution, fluid flow and ore genesis that can assist exploration for paleovalley-hosted uranium deposits. Precise geometric definition of the basin margin and paleovalley architecture is important in identifying exploration targets and improving the effectiveness of drilling. Refinements in remote sensing, geophysical and data processing techniques, in combination with sedimentological and depositional interpretations, provide an efficient approach for outlining the principal drainage patterns and channel dimensions. To help reduce risk, an exploration strategy should combine these technologies with a detailed understanding of the physicochemical parameters controlling uranium mobilization, precipitation and preservation. [ABSTRACT FROM AUTHOR]

Four recently discovered glacio-fluvial paleovalleys in southeast Jordan and northwest Saudi Arabia are described for the first time. The paleovalleys formed as a result of glacial erosion by series of sub-parallel valley glaciers during the Late Ordovician (Hirnantian) southern hemisphere glaciation on the Arabian Plate. The southwest-northeast orientation of the paleovalleys, Proterozoic erratic clasts and paleocurrent vectors indicate the advance of glaciers and subsequent glacio-fluvial siliciclastics emanating from a paleo-ice sheet located to the south on the Arabian Shield. U-shaped, paleovalley cross-sectional morphologies and gently inclined longitudinal profiles indicate initial glacial erosion of the 'finger-like' paleovalleys, probably as wet-based valley glaciers, eroded up to 250 m depth into Late Ordovician marine bedrock formations. Paleovalley-fill sequences comprise a tripartite upwards succession: (a) basal sandstone-dominated tillite with well-rounded, grooved and striated granitoid and metamorphic basement clasts derived from the Proterozoic Arabian Shield together with locally derived, rounded and elongate boulders eroded from the local bedrock at the margins of the paleovalleys (Retrogradational Lowstand Sequence); (b) green chloritic siltstone (Zarqa Formation) deposited during a progradational sea-level rise with marine influence (Transgressive Sequence); (c) coarse-grained, trough cross-bedded sandstone (Sarah Formation) attributed to progradational fluvial sedimentation as glacial outwash. Rapid sea-level rise during latest Hirnantian to Early Llandovery time resulted in marine flooding of the glacio-fluvial alluvial plain and deposition of organic-rich mudstones representing transgressive and high-stand sequences. [ABSTRACT FROM AUTHOR]

Hydrogeological district 2242 - the Kuřim Basin (HGD 2242) lies NNW of the Brno city. The project "Groundwater balance in the selected areas of the Czech Republic" implemented by the Czech Geological Survey provided an opportunity to process and interpret data from many earlier drilled boreholes, geological maps and other records from this HGD. Several new boreholes enabled new recordings of groundwater behaviour and also provided data on lithology. The well logging also allowed to upgrade the position of individual beds and their lithology. The character of NW termination of hydrogeological district was verified by geophysical methods on P1 and P2 profiles, where vertical electrical sounding (VES) and electrical profiling (DOP) in dipoledipole array were used. Electrical resistivity tomography (ERT), dipole electromagnetic profiling (DEMP) and shallow seismic refraction survey (MRS) were employed only in selected sections of the profiles. The Tišnov Fault (NW-SE trending zone) in particular demarcates areas with different development which is reflected in distribution of sediments of various stratigraphic levels. While the central part represents tectonically the most affected, and simultaneously the most sunken area with relatively large thickness of Badenian sediments (more than 100 m), the marginal parts in the NE (Sebrov, Milonice) and in the SW (Vohančice, Čebín-Chudčice and Jinačovice) represent remodelled relics of Lower Miocene valleys filled with Ottnangian sediments the thickness of which only rarely exceeds 50 meters. Moreover, the lithology of both the above-mentioned types of sediments is also different. Ottnangian sediments consist of a sequence of alternating sands, gravels and clays with coal seams. Lower Badenian sediments are represented by marine calcareous clays that form most of their thickness, whereas coarse-grained clastics occur only on their basis. One of the project objectives was also to create a contour model of the base of Miocene sediments. Consequently, a border line defining the extent of Miocene sediments was established. It should become a new boundary of the hydrogeological district enabling balancing the groundwater supply and demand in the future. This contour model was derived from data obtained from the newly drilled boreholes and from the results of geophysical methods that allowed to create a concept of changing paleoflow of the Svratka River during the Neogene and Quaternary. The Pre-Ottnangian course of the Paleo-Svratka River is not clear. It later sinks along the Tišnov Fault forming a pre-Badenian valley trending approximately in the direction of Stěpánovice-Drásov-Kuřim-Brno. The valley was later filled with marine sediments markedly exceeding the current relief level. The tectonic vertical movements and blocks tilting continued in Badenian and post-Badenian time so the Svratka River direction moved to its recent position maybe partly similar to pre-Ottnangian. [ABSTRACT FROM AUTHOR]

En este trabajo se analiza la expresión estratigráfica y significado geológico de la superficie que separa a las formaciones Vinchina (Mioceno) y Toro Negro (Mioceno Tardío-Plioceno), las que afloran conformando la Sierra de Los Colorados (oeste de la provincia de La Rioja). El estudio se realizó mediante el levantamiento de 6 secciones detalladas, de norte a sur: quebrada de La Aguada, quebrada de Los Pozuelos, río de La Troya norte, río de La Troya sur, Campo Negro y quebrada del Yeso. La información reunida en estos perfiles permitió comprobar que el contacto entre ambas unidades queda definido por una superficie de incisión de alto relieve relativo que suprime, en algunos sectores, hasta un 25% de la Formación Vinchina. La superficie en cuestión forma un paleovalle en el sector norte (secciones de La Aguada y Los Pozuelos), se manifiesta como una superficie de incisión ondulada (con mínima supresión estratigráfica) en la parte central del área estudiada (secciones de río de La Troya sur y Campo Negro) y pierde relieve hacia el sur hasta transformarse en una superficie relativamente plana (sección de quebrada del Yeso). El análisis de los depósitos sobrepuestos a la superficie de incisión permitió la definición de cuatro secciones estratigráficas. La sección S1 está compuesta por conglomerados extraformacionales, aglomerados y brechas intraformacionales. En la sección S2 predominan conglomerados gruesos hasta finos, areniscas guijarrosas y areniscas gruesas siendo muy escasas las pelitas y areniscas muy finas. La sección S3 comprende ciclos granocrecientes formados por pelitas, areniscas y conglomerados. Finalmente, la sección S4 comprende pelitas y areniscas finas con limitada participación de conglomerados y areniscas gruesas. La sección S1 es interpretada como depósitos confinados bajo condiciones de bajo espacio de acomodación. La sección S2 también fue formada en condiciones de confinamiento pero dentro de un esquema de espacio de acomodación creciente. Finalmente, las secciones S3 y S4 indican la pérdida de confinamiento del sistema y el estado de máximo espacio de acomodación. La génesis de la superficie de incisión que separa a las formaciones Vinchina y Toro Negro es, en este trabajo, relacionada a las fases principales del ascenso del Famatina occidental.The stratigraphic expression and geological significance of the contact between the Vinchina (Late Miocene) and Toro Negro (Late Miocene-Pliocene) formations (Turner, 1964; Ciccioli et al., 2010) is analyzed in this paper. These units with more than 8,000 m of sediments (Ramos, 1970; Tripaldi et al., 2001; Ciccioli, 2008) represent the main units of the infill of the Vinchina Basin (Ciccioli et al., 2010) (Figs. 1-3) during the transition from a simple foreland basin stage to a broken foreland one (Ciccioli, 2008; Ciccioli, et al., in press). They mostly represent sedimentation by fluvial and aeolian processes in an inland basin during an overall warm and dry climate period (Tripaldi et al., 2001; Ciccioli, 2008). Thus, major changes in sedimentation are though to correspond with tectonic events (Ciccioli et al., in press). The lower member of the Vinchina Formation and the upper member of the Toro Negro Formation present a more uniform and extended sedimentation pattern. In contrast, the upper member of the Vinchina Formation and the lower member of the overlying Toro Negro Formation show important lateral (north-south) facies changes (Fig. 4). The along-strike differences in the character of the discontinuity marking the boundary between the Vinchina and Toro Negro formations, is the most meaningful of them all. Six sections, from north to south (La Aguada creek, Los Pozuelos creek, north La Troya river, south La Troya river, Campo Negro and del Yeso creek) were measured across the boundary between the Vinchina and Toro Negro formations along the Sierra de Los Colorados (Fig. 2). Facies associations within this interval were defined and sedimentary paleoenvironments interpreted. The information gathered from these sections allowed interpreting the contact between the Vinchina and Toro Negro formations as a high-relief incision surface that in some places suppresses up to 25% of the underlying Vinchina Formation (Figs. 4 and 5). This surface forms a west-east oriented paleovalley in the north (La Aguada and Los Pozuelos sections), is a low-relief incision surface (showing minimum stratigraphic suppression) in the central part of the study area (south La Troya river and Campo Negro sections) and becomes in a non-erosive planar surface at the southern end (del Yeso creek, Figs. 6 and 7). Considering the available radiometric data (Ciccioli et al., 2010), the age of the unconformity can be bracketed between 19.1 and 8.6 Ma. Four stratigraphic sections were defined in the deposits of the Toro Negro Formation overlying the incision surface (Table 2). Section S1 is composed of extraformational conglomerates, agglomerates and intraformational breccias. Coarse-grained conglomerates, gravelly sandstones and coarsegrained sandstones predominate in section S2 together with scarce mudstones and very fine-grained sandstones. Section S3 comprises coarsening-upward sequences composed of mudstones, sandstones and conglomerates. Finally section S4 is made up by mudstones and fine-grained sandstones with scarce levels of conglomerates and coarse-grained sandstones. Section S1 is interpreted as incision-confined fluvial deposits accumulated under low-accommodation conditions. Section S2 is also interpreted as confined to the paleovalley but with increasing accommodation space. Finally sections S3 and S4 mark the shift from confined to unconfined conditions under high accommodation. The Vinchina Formation was reported to crop out in the higher areas of the Famatina range but up to now there is no record of the Toro Negro Formation in that area. The deep, long-lived, west-east oriented paleovalley described in the northern part of the area is an atypical feature for the foreland basin model. However, the lack of a relationship with contemporaneous marine deposits and evidences of an arid climate throughout the deposition of the Vinchina and Toro Negro Formations suggest a tectonic control for the changes in the erosion vs accumulation rates in the basin. Therefore the incision and infill of the paleovalley is interpreted using the relationship between the fluvial equilibrium-profile and the channel profile (C.f. Dalrymple et al., 1998; Shanley and McCabe, 1994; Blum and Törnqvist, 2000) (Fig. 8) The meandering fluvial system interpreted from deposits of Facies Association (FA) V of the Vinchina Formation (Tripaldi et al., 2001) represents a stage of high accommodation (point A in Fig. 8). After that stage, a progressive lowering of the relative equilibrium profile reduces the accommodation the development of amalgamated channel belts of the fluvial systems interpreted for FA VII (Tripaldi et al., 2001) similar to the "unconfined stream equilibrium profile low" of Dalrymple et al. (1998).This trend continued until the equilibrium profile places below the channel profile. At that point erosion and sediment bypass took place. The major degree on incision and sediment bypass occurred at point C in figure 8 but erosion and down-cutting occurs until point E. At this latter point the equilibrium profile passes above the stream profile and aggradation begins within the incised valley ("confined stream equilibrium profile low" de Dalrymple et al., 1998). Finally, maximum accommodation (point F in figure 8) is represented by the anastomosing fluvial system with encased channels in fine-grained overbank deposits of section S4. As neither the west-east orientation of the observed paleovalley nor the evolution of the sedimentary environments can be explained by the eastward advance of the fold and thrust belt in a simple foreland basin we interpret that the uplift of the Famatina range (cf. Ramos et al., 2002; Davila and Astini, 2007; Davila, 2010) to the east of the studied area (Fig. 9) might have produced a narrow area of high subsidence modifying the stream profiles of the rivers draining from the Andes. In the distal area (Los Colorados range) stream profile dropped below the equilibrium profile causing deep incision while close to the uplifted range rapid deposition might have occurred. Therefore the incision surface separating Vinchina and Toro Negro Formations is related to the main phases of uplift of the western Famatina range (Figs. 10 y 11). This event produced accelerated subsidence and increased accommodation in the proximal area and lowering of the equilibrium fluvial profiles (and incision) in the distal areas to the west (Fig. 10b). During post-tectonic times, subsidence and accommodation rates decrease close to the uplifted area and the relative rise of the fluvial equilibrium profiles in the distal area with renewed aggradation (Fig. 10c). A model explaining the interpreted changes in accommodation relative to the subsidence due to the uplift of the Famatina is shown in figure 11.

A buried paleovalley system, up to 2 km wide and exceeding 50 m in relief, made up of multiple cross-cutting depressions incised into the Lower Pleistocene bedrock, is reported from the central Adriatic coastal plain at the mouth of Biferno River. Through a multi-proxy approach that included geomorphological, stratigraphic, sedimentological and paleontological (benthic foraminifers, ostracods and molluscs) investigations, the facies architecture of distinct, superposed valley fills is reconstructed and their relative chronology established along a transverse profile with extremely high data density (average borehole spacing 75 m). Regional tectonic uplift appears as the major controlling factor of initial (Middle Pleistocene) river down-cutting and paleovalley formation. In contrast, glacio-eustatic fluctuations drove fluvial-system response over the last 120 ky, when valley incision was primarily induced by the last glacial base-level lowering and climatic forcing. A fragmented record of coastal and shallow-marine deposits is available for the lower paleovalley fill, which is penetrated by a limited borehole dataset. Multiple erosion phases probably related to the post-MIS 5e sea-level fall are reconstructed from the upper paleovalley fill, where a buried fluvial terrace succession is identified a few tens of meters below the ground surface. The flat surfaces of two buried fluvial terraces suggest longer-term, stepped relative sea-level fall, and are correlated with fluvial incisions that took place possibly at the MIS 5/4 transition and at the MIS 3/2 transition, respectively. A laterally extensive gravel body developed on the valley floor during the Last Glacial Maximum. During the ensuing latest Pleistocene–early Holocene sea-level rise the Biferno paleovalley was transformed into an estuary. Upstream from the maximum shoreline ingression, the vertical succession of well-drained floodplain, poorly-drained floodplain, and swamp deposits evidences increasing marine influence in the estuary, in response to continuing sea-level rise. The interfluves were drowned around 8 cal. ky BP, when brackish conditions developed in the study area. Decreasing marine influence in the uppermost 15 m of the paleovalley fill suggests the onset of the modern delta: when the rate of sea-level rise was overwhelmed by sediment supply, delta progradation took place. [ABSTRACT FROM AUTHOR]

The Liverpool Plains in northern New South Wales contain some of the best agricultural land in Australia and are underlain by extensive smectite clay-dominated soils sourced from weathering the alkali basalts of the Liverpool Ranges. It had been thought that a relatively simple geological model explained the underlying Cenozoic sequence with salt-rich clays of the Narrabri Formation overlying sands and gravel aquifers comprising the Gunnedah Formation. Extensive groundwater modelling based upon this simple conceptualisation has been used in management plans proposed by the mining and agricultural industries. A 31.5 m core has been recovered using minimally disturbed triple-tube coring methods at Cattle Lane (Latitude –31.52° S, Longitude 150.47° E) to resolve uncertainty concerning the aquitard status of the upper layer. Recovered core has been examined and tested to determine grainsize, cation-exchange capacity, X-ray diffraction, X-ray fluorescence and microscopic examination of granular components. These measurements complement surface and borehole geophysical techniques, hydrogeological data and hydrochemical analysis of water samples recovered from a series of specially constructed piezometers adjacent to the cored hole. The sequence overlies a Late Cretaceous channel cut into Permian bedrock at 91 m depth with sands and clays below 31.5 m considered to represent various alluvial fill events mostly occurring since the Early Pliocene. Erosion of Late Eocene alkali basalts on the Liverpool Ranges, with the formation of smectite clays, pedogenic carbonates and with the addition of quartz from both eolian sources and locally derived from adjacent Triassic sandstone hills, provides the great majority of the sediment recovered from the cores. Late Pleistocene (114 ka) to Holocene ages were determined for the core from three optically stimulated luminescence (OSL) measurements on fine sands (13, 23 and 29 m BG). Detailed examination has failed to detect any evidence of a boundary between Narrabri and Gunnedah formations revealing rather a gradual change in dominance of clays and silts over sands and gravels embedded in a clay-rich matrix. This result challenges the conceptualisation used to conduct groundwater modelling on the Liverpool Plains. [ABSTRACT FROM AUTHOR]

The formation of paleovalleys in mountainous regions is considered to result from extreme events such as landslides and glacial or landslide lake outburst floods. According to IPCC (2012) the extreme events are rarest of the rare weather/climatic events when the climate/weather variable is significantly above or below the defined threshold value. The present study suggests that paleovalleys can also form during years long periods of valley aggradation. A series of paleovalleys thus formed runs parallel to the present river course. In this study, we suggest that paleovalleys in the Alaknanda valley of the Central Himalaya have formed in two ways: 1) major valley aggradation and 2) local events of landsliding and lake breaching. Most of the paleovalleys in the Alaknanda valley formed during a major valley aggradation phase (between 15 and 8 ka). Paleovalleys formed due to local landsliding also formed around 8 ka. Local landslides were triggered due to high rainfall in lower valley reaches during unstable climatic conditions. Therefore, the formation of paleovalleys both by regional and local mode within 15–8 ka indicates that the valley was receiving excess sediment from upper catchment as well as from lower reaches during this period. This phase of excess sediment supply and valley aggradation coincides well with post glacial climatic amelioration. Therefore the study underlines the role of climate in the time scales of 10 3 years in shaping the landscape of an active mountain like the Himalaya. The role of other landscape changing agencies such as tectonics and erosion is not accounted in the present study. [ABSTRACT FROM AUTHOR]

In order to better constrain the relationship between tectonics and sedimentation of the Eastern Sardinian Margin, from the Messinian to the present day (METYSS project), a lithostratigraphic study was carried out on the Late Neogene deposits along the Cedrino Valley (eastern Sardinia). The late Neogene evolution is documented from sedimentological and tectonic analysis, biostratigraphic dating, and by mapping and logging stratigraphic sections. Previous authors have differentiated an early Pliocene marine formation from an older continental formation, possibly Miocene, the entire system being covered by late Pliocene to Quaternary lava flows. Preliminary biostratigraphic data suggest the absence of the lowermost Pliocene, based on the absence of Globorotalia margaritae and the presence of Globorotalia puncticulata , implying a sediment age between 3.81 and 2.41 Ma. At the foot of the Fiuli cliff, some mud clasts include a coccolith microflora, Tortonian in age, suggesting reworking. The Pliocene marine deposits consist of a single filling sequence instead of a succession of superimposed sequences as we would expect during this period of time; the occurrences of terms rarely respect the usual transgressive-regressive succession. Contrasting bathymetric environments (fore-shore, pro-delta, shelf or upper slope) can be abruptly superimposed on top of the other, along few meter thick intervals. A rapidly flooded term is observed in several sites and indicates a spatial variability over only a few kilometers distance. Some deep water deposits are in the middle of the infilling Pliocene sequence, whereas shallower water deposits can be repeated along a vertical section, or even interrupted by emersion. These marked differences can express syn-, or possibly post-sedimentation tectonic uplifts. The 10–25° bed dips originated through local tectonic uplift. At Fiuli, the geometry of the bedding planes is indicative of tilting toward the west, in a direction opposite to the one observed at Onifai. These Pliocene series form a wide syncline with an approximately NNE–SSW axis. This morpho-structural behavior appears to be largely atypical of this East-Sardinian coastal area. [ABSTRACT FROM AUTHOR]

The Frome airborne electromagnetic (AEM) survey was designed to provide reliable pre-competitive AEM data to aid the search for energy and mineral resources around the Lake Frome region of South Australia. Flown in 2010, a total of 32,317 line kilometres of high-quality airborne geophysical data was collected over an area of 95,450 km2at a flight line spacing mostly of 2.5 km, opening to 5 km spaced lines in the Marree–Strzelecki Desert area to the north. The Lake Frome region hosts a large number of sandstone-hosted uranium deposits with known resources of ∼60 000 tonnes of U3O8including the workingIn SituRecovery operations at Beverley, Pepegoona, Pannikin and Honeymoon, and deposits at Four Mile East, Four Mile West, Yagdlin, Goulds Dam, Oban, East Kalkaroo, Yarramba and Junction Dam. The aims of the Frome AEM Survey were to map and interpret critical elements of sandstone-hosted uranium mineral systems including basin architecture, paleovalley morphology, sedimentary facies changes, hydrological connections between uranium sources and uranium deposition sites and structures. Interpretations of the data show the utility of regional AEM surveying for mapping crucial elements of sandstone-hosted uranium mineral systems as well as for mapping geological surfaces, structures and depth of cover over a wide area. Data from the Frome AEM Survey allow mineral explorers to put their own high-resolution AEM surveys into a regional context. Survey data were used to map and interpret a range of geological features that are associated with, or control the location of, sandstone-hosted uranium mineral systems and have been used to assess the uranium prospectivity of new areas to the north of the Flinders Ranges. [ABSTRACT FROM PUBLISHER]

We have produced a morphostructural map to explore the tectonic geomorphology of the Lucania part of the southern Apennines mountain front to assess the relative role that tectonic and erosion processes played in shaping the topography of this part of the orogen. Data were collected mainly through field work and airphoto interpretation. The main morpho-tectonic elements seem to be affected by out-of-sequence thrusting and wide regional uplift which played an important role in the latest stage of orogenic wedge evolution. The geomorphic expression of the local tectonics of individual structures reflects the structural and stratigraphic heritage and were overprinted in the Middle Pleistocene when regional rock uplift lifted the entire mountain front and its foredeep above sea level, imparting a new tectonic slope that dictates erosion and landscape evolution to the present day. Distinct geomorphological features such as asymmetrical ridges, relict valleys and paleosurfaces, have developed on rocks of variable durability and are exposed by regional uplift and erosion along non-cylindrical structures, fault transfer zones, and lateral ramps. This map also identifies for the first time a relict strike valley at the mountain front and a set of geomorphic markers that highlight the particular relationship between drainage evolution and thrusting. [ABSTRACT FROM AUTHOR]

The Castle Conglomerate Unit in the Poruba Member (Early Namurian, Mississippian) is a lithosome composed of coarse-grained sandstones and conglomerates. Its thickness, lithology and extensive area make it unique in the paralic sequence of the Ostrava Formation of the Upper Silesian Basin. The unit was studied on the basis of information from exploratory boreholes, mines and its outcrop at the type locality in the Lučina Valley in Silesian Ostrava. Locally, the unit attains a thickness of up to 115 in (average 24.4 m). Its present-day area is approximately 992 km2. The axis of the conglomerate facies (with character of interbeds) in the unit has a NNE-SSW alignment and coincides with the axis of the basin' s maximum subsidence during the sedimentation of the Poruba Member. The maximum aggregate thickness of the conglomerate facies is 60 m; their present-day area of occurrence is approximately 480 km2. The Castle Conglomerate Unit represents deposits of a low-sinuosity river system. The upper part of the multistorey channel fill is characterised by channels filled with sand bedforms and occasional bars. Palaeocurrents show a low spread of vectors, primarily to the NNW. The lower part does not crop out; it is known, therefore, only from boreholes. The presence of the unit's coarse-grained clastics inside the basin filling, which is dominated by siltstone and medium-grained sandstone, indicates a major drop in the base level, which is interpreted here as a drop in the sea level. We correlate this event with the major glacio-eustatic sea level drop at 323 Ma that can be connected with the onset of glaciation interval C2 of the Late Paleozoic Ice Age. Because the resolution of available stratigraphic and geochronologic data is not currently sufficient, an alternative explanation of the tectonic origin cannot be ruled out of the discussion and may also be valid in regard to the active Variscan foreland. [ABSTRACT FROM AUTHOR]

Highlights: [•] Geophysical data paired with hydrologic data show geologic control of SGD patterns. [•] Geologic heterogeneity affects groundwater salinity distribution and flowpaths. [•] Complex flowpaths promote mixing with implications for chemical fluxes to estuaries. [ABSTRACT FROM AUTHOR]

Deeply incised river networks are generally regarded as robust features that are not easily modified by erosion or tectonics. Although the reorganization of deeply incised drainage systems has been documented, the corresponding importance with regard to the overall landscape evolution of mountain ranges and the factors that permit such reorganizations are poorly understood. To address this problem, we have explored the rapid drainage reorganization that affected the Cahabón River in Guatemala during the Quaternary. Sediment-provenance analysis, field mapping, and electrical resistivity tomography (ERT) imaging are used to reconstruct the geometry of the valley before the river was captured. Dating of the abandoned valley sediments by the 10Be-26 Al burial method and geomagnetic polarity analysis allow us to determine the age of the capture events and then to quantify several processes, such as the rate of tectonic deformation of the paleovalley, the rate of propagation of post-capture drainage reversal, and the rate at which canyons that formed at the capture sites have propagated along the paleovalley. Transtensional faulting started 1 to 3 million years ago, produced ground tilting and ground faulting along the Cahabón River, and thus generated differential uplift rate of 0.3 ± 0.1 up to 0.7 ±0.4 mm ⋅ y-1 along the river's course. The river responded to faulting by incising the areas of relative uplift and depositing a few tens of meters of sediment above the areas of relative subsidence. Then, the river experienced two captures and one avulsion between 700 ky and 100 ky. The captures breached high-standing ridges that separate the Cahabón River from its captors. Captures occurred at specific points where ridges are made permeable by fault damage zones and/or soluble rocks. Groundwater flow from the Cahabón River down to its captors likely increased the erosive power of the captors thus promoting focused erosion of the ridges. Valley-fill formation and capture occurred in close temporal succession, suggesting a genetic link between the two. We suggest that the aquifers accumulated within the valley-fills, increased the head along the subterraneous system connecting the Cahabón Fiver to its captors, and promoted their development. Upon capture, the breached valley experienced widespread drainage reversal toward the capture sites. We attribute the generalized reversal to combined effects of groundwater sapping in the valley-fill, axial drainage obstruction by lateral fans, and tectonic tilting. Drainage reversal increased the size of the captured areas by a factor of 4 to 6. At the capture sites, 500 m deep canyons have been incised into the bedrock and are propagating upstream at a rate of 3 to 11 mm ⋅ y-1 while deepening at a rate of 0.7 to 1.5 mm ⋅ y-1. At this rate, 1 to 2 million years will be necessary for headward erosion to completely erase the topographic expression of the paleovalley. It is concluded that the rapid reorganization of this drainage system was made possible by the way the river adjusted to the new tectonic strain field, which involved transient sedimentation along the river's course. If the river had escaped its early reorganization and had been given the time necessary to reach a new dynamic equilibrium, then the transient conditions that promoted capture would have vanished and its vulnerability to capture would have been strongly reduced. [ABSTRACT FROM AUTHOR]

Cenozoic fluvial sediments present west of the Meckering Line occur at similar elevation ranges (mostly 200-260 m AHD) in the largely rejuvenated forested landscapes of the Darling Plateau between the Helena River catchment and the south coast of Western Australia. These widespread paleovalley sediments are more continuous than previously recognised, and possess common hydrogeological characteristics. The upper parts of catchments in southwest Western Australia are flat and poorly drained with widespread salt lakes and wetland systems developed on the sediments. The lower rejuvenated landscapes below the base of remnant sediments, which are locally marked by saline springs and right angle changes in river courses, have undulating topography with well-defined drainage lines cut into competent basement rocks. This paper identifies groundwater flow systems associated with the paleovalley sediments in three varied catchments and describes the role of the Cenozoic sand aquifer in the development and potential management of dryland salinity. Groundwater flow in the Cenozoic paleovalley sand aquifer has more significance for land and water salinisation than that in the local weathered basement. The sand aquifer is a conduit for salt mobilised from weathered basement following land clearing. Erosion of the sedimentary profile by rejuvenation has exposed this sand aquifer within specific elevation ranges in modern drainages facilitating saline groundwater discharge, and land and water salinisation. In the Helena River catchment 63% of the salt load to the Mundaring Reservoir is discharged through this sand aquifer in only 30% of the streamflow. Such mismatched salt load and flow means southwest landscapes respond differently to key dryland and stream salinity management actions. Revegetation to reduce the salt load should target areas of weathered basement locally discharging saline groundwater to the sand aquifer. Reforestation elsewhere in the rejuvenated bedrock landscape can, by contrast, reduce the streamflow (that is diluting large salt loads from the remnant sedimentary landscapes) and hence raise the overall stream salinity. [ABSTRACT FROM AUTHOR]

The Bland Basin is the broad alluviated paleovalley of Bland Creek, a tributary of the Lachlan River in the central part of New South Wales, Australia, within the drainage basin of the Murray-Darling river system. It covers about 4000 km2 and contains up to 120 m of terrestrial sediments, interpreted as being deposited by alluvial, colluvial, lacustrine/paludal and eolian processes. It is undated, but is likely to be coeval with the downstream contiguous fill of the Lachlan River paleovalley, dated elsewhere by palynology as Miocene to Holocene. The southwestern part of the basin has been studied in detail using airborne geophysics (electromagnetics, magnetics and gamma-ray spectrometry) and drilling. The small erosional catchment area of the modern basin surface has resulted in a paucity of sediment available for deposition in the basin, but the drainage base-level has been driven by the rate of sedimentation of the Lachlan paleovalley downstream of the basin. Therefore, most of the sediment derived from the catchment has been trapped in the basin rather than being transported downstream and into the Lachlan paleovalley, and at times large lakes and/or swamps have formed in the central part of the basin. The sediments in the southwest of the basin are dominated by clay and silt, with local sand and gravel, mostly in basal gravelly sand and a sandier interval in the middle part of the sequence. Quartz silt derived from eolian dust is a major component of the upper part of the sedimentary sequence. Geophysical responses of the sediment include high conductivity due to saline groundwater, low gamma response dominated by thorium decay emissions due to the leached nature of the sediment, and short-wavelength-low-amplitude magnetic anomalies resulting from local concentrations of detrital maghemite-rich gravel formed during weathering in the catchment area. Broad valleys draining to the Lachlan River west of the Bland Basin may contain similar mud-dominated Neogene basins, but a lack of drill data precludes detailed interpretation. [ABSTRACT FROM AUTHOR]

Abstract: Wadi Tayiba is located along the western margin of the Hammam Faraun fault block, western Sinai, Egypt and is generally thought to contain exposures of the ‘type-section’ for late pre-rift to early syn-rift stratigraphy associated with the Oligo-Miocene Suez Rift. Previous studies have suggested a complex vertical succession of sedimentary facies characterise the late pre-rift to early syn-rift and imply major and abrupt variations in relative sea-level during this time. Detailed sedimentological and stratigraphic analysis of the Wadi Tayiba type-section presented in this study identifies not only a far simpler vertical facies succession than previously suggested but also the development of a major paleovalley system at the base of the early syn-rift succession. It is suggested that this subtle but significant feature is the cause of the complex vertical facies succession previously interpreted. It is concluded that continuous marine sedimentation and only moderate amplitude variations in relative sea-level occurred during the Eocene to Early Oligocene within at least this part of the Suez Rift. A major relative sea-level fall occurred during the middle Oligocene and a regionally developed erosional surface associated with this event marks the contact between late pre-rift and early syn-rift strata. The results of this study have major implications for sub-regional correlations of late pre-rift to early syn-rift stratigraphic units and resultant palaeogeographic reconstructions of the late pre-rift to early syn-rift period. [Copyright &y& Elsevier]

This paper focuses on a small back-barrier sand-island on the southeast coast of Queensland. The freshwater lens in the study area exhibits anomalously high short-range salinity gradients at shallow depths, which cannot be explained using a standard seawater intrusion model. The island groundwater system consists of two aquifers: a semiconfined aquifer hosting saline to hypersaline groundwater and an overlying unconfined freshwater aquifer. The deeper aquifer is semiconfined within an incised paleovalley, and groundwater flow is restricted to an east - west direction. Tidal response observations show that the tidal signal propagates far more rapidly and is of much higher magnitude in the semiconfined aquifer than the unconfined aquifer. The tidal wave-pulse amplitude is also subject to greater attenuation in the unconfined aquifer. A conceptual hydrogeological model illustrates how upwelling of hypersaline groundwater, induced by density-dependent flow and tidal pumping, has contaminated the shallow groundwater resource. Salinisation at shallow depths is restricted to an area proximal to the paleovalley aquifer. The spatial distribution of lithological heterogeneity is an initial limiting control on the movement of the upwelling saline plume. The extent of shallow groundwater contamination is also limited by the presence of a baroclinic field, resulting from lateral variations in fluid density. Hydrochemical signatures have been used to support the model hypothesis and link the salinisation of fresh groundwater with the semiconfined aquifer as opposed to the surrounding estuarine surface water. The geometry and thickness of the freshwater lens are further controlled by the presence of the largely impermeable bedrock paleosurface between 9 and 12 m depth. The combination of hypersaline groundwater and hydraulically restrictive lithology at shallow depths has produced excessive thinning of the freshwater lens, demonstrating that the application of a model such as the Dupuit - Ghyben - Herzberg relationship would grossly overestimate the available groundwater resource. [ABSTRACT FROM AUTHOR]

In the western Great Basin of North America, a system of dextral faults accommodates 15%–25% of the Pacific-North American plate motion. The northern Walker Lane in northwest Nevada and northeast California occupies the northern terminus of this system. This young evolving part of the plate boundary offers insight into how strike-slip fault systems develop and may reflect the birth of a transform fault. A belt of overlapping, left. stepping dextral faults dominates the northern Walker Lane. Offset segments of a W-trending Oligocene paleovalley suggest ∼20–30 km of cumulative dextral slip beginning ca. 9–3 Ma. The inferred long-term slip rate of ∼2–10 mm/yr is compatible with global positioning system observations of the current strain field. We interpret the left-stepping faults as macroscopic Riedel shears developing above a nascent lithospheric-scale transform fault. The strike-slip faults end in arrays of ∼N-striking normal faults, suggesting that dextral shear diffuses into extension in the Great Basin. Coeval extension and dextral shear have induced slight counterclockwise fault-block rotations, which may ultimately rotate Riedel shears toward the main shear zone at depth, thus facilitating development of a throughgoing strike-slip fault. [ABSTRACT FROM AUTHOR]

Chronic erosion of beaches along the eastern Texas barrier island coast is increasingly mitigated by renourishment efforts that periodically place large volumes of sand onshore. Location of beach-quality sands on the inner continental shelf is challenged in an environment where terrestrial rivers deposit fluvial sediments in back bays and lagoons instead of offshore and by shelf areas that are dominated by muds. The search for beach-quality sands thus requires understanding of the coastal geological framework and morphodynamic processes that accompanied late Quaternary evolution in the northern Gulf of Mexico. The occurrence of surficial sand deposits as positive bathymetric features on the seafloor (ridges, shoals, banks) and presence of sands buried in paleovalley (drowned channels) infill sequences makes for complicated search procedures that must accurately differentiate a range of sedimentary settings by geophysical and geotechnical surveys. Compilation of vast amounts of data from historical core logs and newly acquired information in a marine information system (MIS) permits spatial analyses in a format that is compatible with development of a sand search model. The resulting differentiated investigative sand-search methods, that comprise part of the Texas Sand Search Model (TSSM), are able to target potential borrow areas in ebb-tidal shoals, low-relief ridge deposits, high-relief banks, and in mud-covered paleovalley sequences. [ABSTRACT FROM AUTHOR]

The Lower Paleozoic detrital succession of the half-graben Kandi Basin in West Africa (Niger-Benin) is about 600 m thick and rests unconformably on the Pan-African basement. Along the western edge of the basin, the base of the succession locally features large glacial fault-bounded paleovalleys. These valleys are filled by the lowermost continental deposits of the We´re´ Formation characterized by massive diamictites with dropstones, and coarse to conglomeratic sandstones associated with large-scale channel structures and internal erosional truncations. The uppermost braided-river deposits of the We´re´ Formation deposited across the entire basin are overlain by the Late Ordovician–Early Silurian storm and tidal sediments of the Kandi Formation, made up of hummocky cross-stratified sandstones and siltstones. Computer-aided analysis of the populations of synsedimentary to synlithification microfaults observed in the Late Ordovician to Early Silurian sediments shows evidence of extensional paleostress tensors with a N90°E to N100°E horizontal σ3 stress responsible for normal displacement along the Kandi Fault. The synsedimentary normal activation of this major fault, inherited from the Precambrian, controls the spatial arrangement of the glacial, braided-stream, storm to tidal, and offshore deposits as well as the deformation of the basin-fill into an asymmetric synsedimentary syncline associated with progressive unconformities. The characterization of glacial features and Late Ordovician deposits from the biostratigraphic distribution of traces of trilobites strongly supports the idea that the deposits of the Kandi Basin are contemporaneous with the melting of the wide ice sheet which overlay the Afro-Arabian Shield during Late Ordovician times. The successive deposits of the We´re´ and Kandi Formations reflect a gradual change from tillites, through glaciofluvial outwash conglomerates (Wa Member), braided-stream sediments (Wb Member), and shoreface barrier sands (Ka Member), to offshore clays and sands (Kb Member). They correspond to reworked, glaciofluvial to marine facies laid down by the Late Ordovician glacial retreat. The Kandi Basin is therefore defined as a staging-post between the Late Ordovician––Early Silurian basins of the Sahara and those of South Africa. [Copyright &y& Elsevier]

During the mid-Carboniferous, ice centers located in present-day western Argentina disappeared until the late Cenozoic with glaciation of the Andes. The disappearance of mid-Carboniferous glaciers and the subsequent climate shift, recorded in the Paganzo Basin, has been attributed to global events and drivers, such as increased atmospheric CO 2 concentrations and the shifting position of Gondwana across the South Pole. However, glaciers continued at the same paleolatitude in eastern South America and did not disappear from Gondwana until the Late Permian. This study investigates links to local drivers that acted in combination with other global drivers to explain the early deglaciation along the western margin of Gondwana. To do this, several outcrops within the eastern portion of the Paganzo Basin in western Argentina were sampled for the Chemical Index of Alteration (CIA) geochemical analyses. Here, we test the applicability of the CIA as a paleoclimate proxy on strata in the Olta-Malanzán paleovalley that historically was thought to have been glaciated. A recent study by the authors has shown that the paleovalley was not glaciated, but owes its origin to extension and excavation by fluvial processes. However, the late Paleozoic stratigraphy of this paleovalley system is similar to the rest of the Paganzo Basin. The results from the paleovalley samples show that this area was intermittently humid and arid through time, but with an overall arid profile. This signature is predominantly due to the nature of the paleovalley, which was subjected to rapid burial from frequent rock falls, progradation alluvial fans/fan deltas, and lacustrine sediment gravity flows (Malanzán Fm.), which prevented any significant chemical weathering. While the overall Pennsylvanian climatic signature appears to be relatively arid (Malanzán, Loma Larga, and Solca Fms.), it seems that the climate during the deposition of the late Pennsylvanian and Permian La Colina Formation was more humid than previously thought. Image 1 • The eastern Paganzo Basin experienced an intermittent humid and arid climate during the Carboniferous-Permian boundary. • Both local and global drivers controlled the climatic transition from periglacial to post-glacial conditions. • Western margin tectonism controlled deglaciation, expanded the rain shadow, and caused aridification in the Paganzo Basin. [ABSTRACT FROM AUTHOR]