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This study of the Aptian lower part of the Carolinefjellet Formation in Svalbard, Norwegian high Arctic, is based on well cores and outcrop section in the Adventdalen area of Spitsbergen and reports on the deposits and bioturbation structures of an ancient subpolar marine shelf from a well-known period of global greenhouse climate. The study documents the sedimentation conditions and benthic fauna activity on a warm-water aggrading shelf subject to harsh Arctic wave climate and eurybatic base-level changes, with episodic bottom incursions of cold polar water. Lithofacies associations and 38 observed ichnotaxa represent subenvironments ranging from offshore to lower shoreface and hosting the Cruziana ichnofacies in its distal to proximal expression, with a brief mid-Aptian encroachment of middle shoreface zone with a distal expression of the Skolithos ichnofacies. The ichnofacies are variously impoverished compared to their archetypes. The sediment bioturbation intensity varies, but similar lithofacies associations show a comparable intensity throughout the stratigraphic succession, which indicates an ichnofauna ecology controlled by the seafloor hydraulic regime and oxygenation, and thus mainly by the wave climate and relative sea-level changes. Sandstone tempestites indicate high-frequency storms, commonly exceeding the magnitude of largest modern hurricane events. The study confirms that a change in global climate mode, such as the Early Cretaceous warming, entails extreme weather conditions. [ABSTRACT FROM AUTHOR]

This case study from the renowned Demänová Cave System in the Carpathians of Slovakia demonstrates that the conventional methods of fluvial sedimentology, combined with an allostratigraphic mapping and speleothem U‐series isotopic dating, can give unprecedented insights into the hydrological history of underground karst conduit. The deposits studied are a relic compound sidebar ranging from gravel to mud and encapsulating the conduit's hydrological history from the middle Pleistocene to the present time. A succession of 10 allostratigraphic units, time‐constrained by speleothems, are recognized in the sidebar deposits, and the corresponding morphodynamics of an evolving cave‐floor sedimentation are reconstructed in considerable detail. The subterranean river water stages recognized from the deposits, time‐constrained by flowstone layers and stalagmites, correlate with and add to the regional record of climate changes. Two distinct episodes of flow ponding (high‐stage slackwater conditions) are recognized and attributed to the independently documented downstream cave‐roof collapses, probably triggered by the Carpathian post‐orogenic earthquakes. This multidisciplinary study may serve as a useful methodological guide for the analysis of fluviokarstic deposits in speleological research and reconstruction of their hosting cave hydrological history. [ABSTRACT FROM AUTHOR]

This study is a reconstruction of the Coniacian palaeogeographic and palaeoenvironmental development in the North Sudetic Basin, a synclinal trough within the Late Cretaceous Central European seaway linking the Boreal and Tethyan marine provinces. The basin formed as an early side effect of the Alpine orogeny combined with the mid‐Cretaceous eustasy, and crucial stages of its evolution occurred during the Coniacian. The basin in the early Coniacian was a long and narrow shallow‐marine embayment with a hypothetical (non‐preserved) bayhead strait funnelling tidal currents. Coalescing tidal sand ridges formed a littoral platform that prograded from the bayhead zone along the basin axis, impinged on laterally by the basin‐margin shoreface and local river deltas. A mid‐Coniacian forced marine regression and closure of the bayhead strait, attributed to the Alpine tectonism combined with eustasy, brought about a dramatic change in the basin, whereby the basin‐wide littoral sand platform emerged and turned briefly into a denudated coastal plain. The late Coniacian eustatic marine transgression formed an in‐place growing coastal sand barrier at the outer edge of the former littoral platform, sheltering a paralic limno‐lagoonal plain with peat‐forming mires. The coastal barrier was eventually drowned by the sea and maximum marine flooding occurred, followed by a normal regression recorded as a rapidly upwards‐shallowing succession of offshore‐transition to fluvio‐deltaic deposits. This case study of the sedimentation pattern in an evolving, tectonically controlled marine embayment contributes to the existing facies models for estuarine embayments formed by a passive marine drowning of large fluvial or glacial valleys. [ABSTRACT FROM AUTHOR]

This study employs facies analysis and basic principles of sequence stratigraphy to correlate isolated outcrop sections and reveal the depositional history of the Chmielnik Formation - a prominent mid-Serravalian clastic wedge formed on the basinward forebulge flank of the Polish Carpathian Foredeep. The coarse-grained clastic wedge, up to 30 m thick and spanning ca 1·1 Ma within biozone NN6, consists of fluvio-deltaic, foreshore and shoreface deposits with a range of large littoral sand bars, all enveloped in muddy offshore-transition deposits. Its dynamic stratigraphy indicates rapid shoreline shifts and environmental changes due to the interplay of forebulge tectonism, sediment supply and third-order eustatic cycles. A similar interplay of tectonism and eustasy is recognizable in the whole middle Miocene sedimentary succession deposited on the forebulge flank, demonstrating an extreme case of an accommodation-controlled shelf and indicating tectonic cycles of the forebulge uplift and subsidence spanning ca 800 to 900 ka. The episodes of forebulge uplift correlate with the main pulses of orogen thrusting. The resulting composite peripheral unconformity differs markedly from the idealized model of a 'steady-state' stepwise onlap driven by forebulge continuous retreat. It is concluded that the foredeep peripheral unconformities, instead of being simplified in accordance with this idealized model, should rather be studied in detail because they bear a valuable high-resolution record of regional events and give unique insights into the local role of tectonics, eustasy and sediment supply. [ABSTRACT FROM AUTHOR]

This study analyses the rhodolith-bearing deposits in the largest and most rhodolith-rich outcrop of the Polish Outer Carpathian flysch, located in the Silesian Nappe, at the village of Melsztyn. The rhodoliths and sparse associated biota occur as resedimented components in a deep-marine succession of siliciclastic conglomerates and coarse-grained sandstones, deposited by high-density turbidity currents and debris flows. The sediment was derived from a fan-delta system located at the southern margin of the Silesian flysch basin. Stratigraphic data indicate that the succession represents the Upper Istebna Sandstone deposited during the Late Paleocene. The rhodoliths are composed mostly of coralline red algae with seven genera and eight species representing the family Sporolithaceae and the subfamilies Mastophoroideae and Melobesioideae. Rhodoliths show sub-spheroidal and sub-ellipsoidal shapes with encrusting, warty and lumpy growth forms. Lumpy growth forms show massive inner arrangements, whereas the encrusting growth forms are usually made of thin thalli and show more loosely packed inner arrangements. The rhodoliths grew on a moderately mobile siliciclastic substrate in a shallow-marine environment with a low net sedimentation rate. It is inferred that the growth of rhodoliths was favored during a relative sea-level rise. During the subsequent sea-level fall, the rhodoliths and associated siliciclastic deposits were resedimented by gravity flows into the deep-sea setting. The analyzed deposits, like other Paleocene-Eocene deposits of the Polish Outer Carpathians, provide no evidence of coeval widespread shallow-marine carbonate sedimentation along the margins of the Outer Carpathian flysch basins. [ABSTRACT FROM AUTHOR]