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The sedimentary features of the Cixerri Formation (Eocene–Oligocene) and its evolution in space and time are described through mapping, investigation of all the significant outcrops, and also by analysing the depositional architecture of well‐exposed and laterally extensive outcrops. The Cixerri Formation marks the middle Eocene Pyrenean unconformity and blankets a former structural ridge‐and‐swale morphology. This started by covering the flanks of the ridges with small alluvial fans and ultimately filled the swales with fluvial deposits in braided to meandering stream environments. In this latter sedimentation phase, the depositional environment of the formation evolved both upwards, and from west to east, to gradually lower energy environments, suggesting a transgressive‐type evolution. The Eocene–Oligocene Cixerri Formation was deposited by a fluvial network with a regular flow regime under a humid–warm climate: This network was formed by a main W‐E‐directed trunk and a NW‐SE‐directed minor branch that ultimately joined together. The Cixerri Formation, which was fed by the erosion of a sector of the Pyrenean Chain, passes upwards to coarser deposits that indicate the transition from a quiet tectonic environment to an active transtensional tectonic phase (Apennine phase). A comparison with similar coeval formations in Northern Sardinia, Corsica, and the Western Mediterranean area (Balearic Islands, France) is attempted, before the significance of the formation in the Pyrenean orogeny is then discussed. [ABSTRACT FROM AUTHOR]

This contribution aims to discuss how gravity-driven processes affect the archaeological record with the goal of building a broad conceptual and methodological framework for dealingwith these contexts. A wide compilation of cases regarding gravity-driven processes is analyzed to recognize relevant environmental factors, the way they affect the properties of the record, and long-term archaeological expectations. Only by understanding the specific mechanisms and processes that occur in each context can an accurate methodological approach be chosen on which to base interpretations. A careful taphonomic study of the spatial distribution, frequency, size, diversity, and orientation of materials comprising the archaeological record is the first step to recognizing formation processes. Actualistic studies provide a framework for discussing the timing and intensity at which processes occur. A detailed geomorphological description is required to interpret sedimentological and micromorphological analysis, which in turn helps understanding of the relative subaerial permanence of the record, its temporal resolution, and preservation potential. Interpreting surface and buried materials requires the understanding of pedogenetic processes. Broad in/off-site spatial sampling strategies definitely yield a more realistic picture about the variety of processes in slope settings. [ABSTRACT FROM AUTHOR]

Complete or near-complete skeletons of the herbivorous dinosaur Hypsilophodon foxii occur frequently in a metre-thick band of mudstone and sandstone in the Lower Cretaceous Wessex Formation of the Isle of Wight. The reasons for this accumulation have been the subject of some debate. This article examines new sedimentological clues that provide a plausible explanation for these dinosaurs' demise. [ABSTRACT FROM AUTHOR]

The Lower Ordovician Shirgesht Formation in central Iran is composed of siliciclastic and carbonate rocks deposited in diverse coastal and marine shelfal environments (tidal flat, lagoon, shoreface, offshore-shelf and carbonate ramp). Five facies associations contain diverse ichnofossil assemblages that show distinct proximal to distal trends formed in a wide range of physical-chemical conditions. The ethological groups of trace fossils in the Shirgesht Formation reflect a gradient of depositional stress conditions across a wave-influenced shoreline and shelf. Deposits of wave-influenced environments make up a significant component of the geological record of shallow marine settings, and the ability to determine paleoenvironments in detail in such successions is critical for reconstruction of depositional histories and sequence-stratigraphic interpretation. The Cruziana ichnofacies of the study shows highly diverse suites that record the establishment of a benthic community under stable conditions and a long-term colonization window. The Skolithos ichnofacies recognized is a low diversity opportunistic ichnocommunity suite that resulted from colonization after tempestite deposition in a stressed environment. The strata record an onshore to offshore replacement of the Cruziana ichnofacies (with abundant feeding traces of deposit-feeders) by the Skolithos ichnofacies (dominated by suspension-feeders and predators). A transitional zone between the two ichnofacies coincides with the offshore-transition/distal lower-surface deposits. The distribution of ichnofacies, the diversity and range of ethological characteristics reflected by the ichnogenera, and the wide range of wave-dominated coastal facies demonstrate the potential to use individual trace fossils and ichnofacies for significantly refined palaeoenvironmental analysis of wave-dominated coastal settings, particularly in Ordovician successions. [ABSTRACT FROM AUTHOR]

Using analyses of the lithology, sequences, paleoenvironment, and tectonic setting, the depositional system of the Carboniferous Huanglong Formation in the eastern Sichuan Basin was identified. The lithological characteristics of the Lower Member, Middle Member, and Upper Member were analyzed and classified. Before the use of carbon, oxygen, and strontium isotopes in the analysis, all of the geochemical data were tested for validity. On the basis of the Z values obtained from carbon and oxygen isotopes, the paleoenvironments of the three members were elucidated. Lower Member was dominantly an enclosed marine environment with intense evaporation and little freshwater input into the sea. Middle Member developed in a semi-enclosed to normal marine environment with many rivers. Upper Member was formed in a normal marine environment. The east Sichuan Basin was enclosed by paleouplifts before the deposition of the Huanglong Formation, forming a relatively enclosed depositional setting. Paleogullies developed in the Silurian strata that underlie the Carboniferous rocks; these paleogullies can be identified. On the basis of a comprehensive analysis, we propose that the Huanglong Formation developed in a platform system. Four microfacies were identified: supratidal flat, dolostone flat, grain shoal, and shelf microfacies. The high-permeability and high-porosity characteristics of the grain shoal microfacies are favorable for hydrocarbon accumulation, while the supratidal flat and shelf microfacies developed very few high-quality reservoirs. The paleogullies, in which increased amounts of grain shoal microfacies developed, controlled the distribution of high-quality reservoirs. [ABSTRACT FROM AUTHOR]

In Eastern Sardinia during the early Middle Jurassic, Alpine Tethys opening triggered the rise of a temporary tectonic high. The high collapsed rapidly, was fragmented into separate blocks, and subsequently covered by continental, transitional, and finally shallow marine deposits forming a narrow depositional system comprising the Genna Selole Fm. Present-day exposures in the southern part of the palaeo-high allow the sedimentological evolution of the transgressive cover sequence to be ascertained. Initial terrestrial deposits comprise alluvial fan deposits located at the mouths of palaeovalleys. These pass into braid-deltas and in the coastal areas located between adjacent valleys mouths, palustrine and coastal plain tidally-influenced environments developed. These environments interfingered laterally and passed seaward into a transitional, siliciclastic to carbonate tidal environment. With the collapse of the tectonic high, the continental to transitional environments were transgressed with deposition of marine carbonates. A comparison with similar coeval deposits of the W-Mediterranean domain has been undertaken. [ABSTRACT FROM AUTHOR]

The late Ediacaran Billy Springs Formation is a little-studied, mudstone-dominated unit deposited in the Adelaide Rift Complex of South Australia. Sediments are exposed in an approximately 11 km × 15 km synclinal structure interpreted as a salt-withdrawal minibasin. The stratigraphic succession is characterized by convolute-laminated slump deposits, rhythmically laminated silty mudstones, rare diamictites and fining-upward turbidite lithofacies. Lithofacies are the product of deposition in a deepwater slope or shelf setting, representing one of the few such examples preserved within the larger basin. Although exact correlations with other formations are unclear, the Billy Springs Formation probably represents the distal portion of a highstand systems tract, and is overlain by coarser sediments of the upper Pound Subgroup. Diamictite intervals are interpreted to be the product of mass flow processes originating from nearby emergent diapirs, in contrast to previous studies that suggest a glacial origin for extrabasinal clasts. Within the spectrum of outcropping minibasins around the world, the sediments described here are unique in their dominantly fine-grained nature and overall lithological homogeneity. Exposures such as these provide an opportunity to better understand the sedimentological processes that operate in these environments, and provide an analogue for similar settings in the subsurface that act as hydrocarbon reservoir-trap systems. [ABSTRACT FROM AUTHOR]

The Salar de Atacama Basin holds important information regarding the tectonic activity, sedimentary environments and their variations in northern Chile during Cretaceous times. About 4000 m of high-resolution stratigraphic columns of the Tonel, Purilactis and Barros Arana Formations reveal braided fluvial and alluvial facies, typical of arid to semi-arid environments, interrupted by scarce intervals with evaporitic, aeolian and lacustrine sedimentation, displaying an overall coarsening-upward trend. Clast-count and point-count data evidence the progressive erosion from Mesozoic volcanic rocks to Palaeozoic basement granitoids and deposits located around the Cordillera de Domeyko area, which is indicative of an unroofing process. The palaeocurrent data show that the source area was located to the west. The U/Pb detrital zircon geochronological data give maximum depositional ages of 149 Ma for the base of the Tonel Formation (Agua Salada Member), and 107 Ma for its middle member (La Escalera Member); 79 Ma for the lower Purilactis Formation (Limón Verde Member), and 73 Ma for the Barros Arana Formation. The sources of these zircons were located mainly to the west, and comprised from the Coastal Cordillera to the Precordillera. The ages and pulses record the tectonic activity during the Peruvian Phase, which can be split into two large events; an early phase, around 107 Ma, showing uplift of the Coastal Cordillera area, and a late phase around 79 Ma indicating an eastward jump of the deformation front to the Cordillera de Domeyko area. The lack of internal deformation and the thicknesses measured suggest that deposition of the units occurred in the foredeep zone of an eastward-verging basin. This sedimentation would have ended with the K-T phase, recognized in most of northern Chile. [ABSTRACT FROM AUTHOR]

Situated at the easternmost area of the Late Mesozoic Jehol Biota, China, abundant fossils, including invertebrates, vertebrates and plants, were collected from the Early Cretaceous Yingzuilazi Formation of the Baishan Basin, southeastern Jilin. The faunal remains from this formation distinctly belong to the Early Cretaceous Lycoptera-Ephemeropsis-Eosestheria assemblage of the Jehol Biota. Based on the gross leaf morphology and epidermal structures, two new species and one indeterminate species of genus Solenites (Czekanowskiales), S. baishanensis sp. nov., S. gracilis sp. nov. and S. sp. are described in this paper. This is the first fossil plant of Czekanowskiales reported from this new fossil locality of the easternmost area of the Late Mesozoic Jehol Biota, China. The new discovery contributes to improve our knowledge for understanding of leaf morphology, epidermal characters and diversity of this genus during the Early Cretaceous time, and extends geologic and geographic distribution of Solenites in northern China and Eurasia. Along with consideration of associated plant and faunal assemblages and sedimentology, we suggest that the regional climate was warm and moderately humid with seasonal temperature and precipitation variations in warm-temperate zone during the Early Cretaceous. [ABSTRACT FROM AUTHOR]

The Mata Amarilla Formation dates from the early Upper Cretaceous and was deposited during a transition in tectonic regime from the extensional Rocas Verdes Basin to the Austral Foreland Basin. Detailed sedimentological logs and architectural parameters were used to define 13 facies associations. The distribution of facies associations and associated variations in fluvial architecture have enabled large-scale changes in accommodation space/sediment supply ratios (A/S ratio) to be defined for the three component sections of the Mata Amarilla Formation. The lower and upper sections are characterized by a high A/S ratio, whereas the middle section corresponds to a low A/S ratio. In the western part of the study area, small-scale variations in the A/S ratio were recognized in the middle section. The strong west to east trend in evolution of the fluvial systems coincides with the direction of propagation of the Patagonian fold and thrust belt, which is located to the west of the study area. Intervals of high A/S ratio (i.e. lower and upper sections) are interpreted to have developed during periods of increased loading by the fold and thrust belt caused by tectonic uplift. In contrast, intervals of low A/S ratio (i.e. middle section) were developed during periods of tectonic quiescence. This article suggests that the large-scale variations in A/S ratios are related to different rates of migration and growth of the Patagonian fold and thrust belt, whereas the small-scale variation occurred in response to specific periods of thrusting and folding in the Patagonian fold and thrust belt (i.e. local loads). This field example of the effects of different scales of variation in A/S ratios across the Austral Foreland Basin could be used to recognize similar tectonically forced variations in stratigraphic architecture in other foreland basins throughout the world, as well as to understand the response of fluvial systems to such changes. [ABSTRACT FROM AUTHOR]

The interpretation of sharp-based shallow-marine sandstone bodies encased in offshore mudstones, particularly transgressive units, has been a subject of recent debate. This contribution provides a multiple-dataset approach and new identification criteria which could help in the recognition of transgressive offshore sandstone bodies worldwide. This study integrates sedimentology, ichnology, taphonomy and palaeoecology of Mulichinco Formation strata in the central Neuquén Basin (Argentina) in order to describe and interpret sharp-based sandstone bodies developed in ramp-type marine settings. These bodies are sandwiched between finer-grained siliciclastics beneath and thin carbonates above. The underlying sediments comprise progradational successions from offshore mudstones to offshore transition muddy sandstones, grading occasionally into lower shoreface sandstones. The surfaces capping the regressive siliciclastics are flat and regionally extensive, and are demarcated by skeletal concentrations and a Glossifungites suite; they are also marked by sandstone rip-up clasts, with encrustations and borings on all sides. These surfaces are interpreted as composite discontinuities, cut during a relative sea-level fall and remodelled during the initial transgression. The overlying transgressive sandstone bodies are 3 to 7 m thick, >4 km long and about three times longer than wide; they are composed of fine-grained sandstones with little lateral change in grain size. Cross-stratification and/or cross-lamination are common, typically with smaller-scale structures and finer grain size towards the top. Large-scale, low-angle (5° to 8°) inclined stratification is also common, dipping at ca 30° with respect to body elongation and dominant currents. These sandstone bodies are interpreted as offshore sand ridges, probably developed under the influence of tidal currents. Intense burrowing is typical at the top of each unit, suggesting an abandonment stage. Final deactivation favoured colonization by epibenthic-dominated communities and the formation of skeletal-rich limestones during the latest transgressive conditions. As partial reworking of pre-existing ridges occurred during this stage, the Mulichinco sandstone bodies are considered the remnants of transgressive offshore sand units. [ABSTRACT FROM AUTHOR]

Discontinuity surfaces are widely recognized but often poorly understood features of epeiric carbonate settings. In sedimentary systems, these features often represent hiatus surfaces below biostratigraphic resolution and may represent a considerable portion of the time contained in the sediment record. From an applied perspective, discontinuities may represent horizontal flow barriers and result in reservoir compartmentalization. Here, a total of 80 condensed surfaces (S1), firmgrounds (S2) and hardgrounds (S3) from a Jurassic (Middle and Upper Bajocian Assoul Formation) ramp setting of the High Atlas in Morocco are carefully documented with respect to their morphology, their secondary impregnation by Fe and Mn oxides and phosphates and their palaeoecological record. A statistical frequency distribution of two surfaces of the S1 type, 1·1 surfaces of the S2 type and 0·4 surfaces of the S3 type per 10 section metres is observed along a 220 m long carbonate succession. Based on two stratigraphically and spatially separated study windows and correlative sections, the stratigraphic frequency distribution, the lateral extent and the nature of facies change across discontinuities are documented in a quantitative manner. Specific features of the study site include the considerable stratigraphic thickness of the Assoul Formation and the conspicuous absence of subaerial-exposure-related features. Based on the data presented here, firmground and hardground surfaces are best interpreted as maximum-regression-related features. Relative sea-level lowstand results in a lowered wave base, and wave orbitals and currents result in sea floor omission and lithification. Care must be taken to avoid overly simplistic interpretations, as differences in bathymetry and carbonate facies result in marked changes in discontinuity characteristics in proximal-distal transects. The data shown here are of significance for those concerned with the interpretation of shoal water carbonate environments and are instrumental in the building of more realistic carbonate reservoir flow models. [ABSTRACT FROM AUTHOR]

Discontinuity surfaces in shallow-marine carbonate successions may represent significant time gaps in the geological record of ancient epeiric-neritic seas. Understanding the hidden geological information contained in major discontinuities is thus of key significance in palaeo-environmental analysis, sequence stratigraphy, reconstructions of sea-level change and basin evolution. In the present paper, the Aptian top Lower Shu'aiba Formation discontinuity in the Sultanate of Oman is taken as a prominent example of a regionally extensive (>100 000 km2) surface with a long (up to 10 Myr) and complex geological history. The top Shu'aiba discontinuity formed on the topographically elevated domain of the Oman platform and represents in essence the Late Aptian time interval. Coeval carbonates in the intrashelf Bab Basin and oceanic rim indicate forced regression and sequence-wise, gradual down-stepping. Available regional, sedimentological, sequence-stratigraphic, petrographic, palaeontological and geochemical evidence from outcrops and cored wells in Oman is summarized, in part complemented by new data, and reviewed in a process-oriented context. In the field, the discontinuity is expressed as a low relief, stained surface with evidence for a marine hardground stage being dominant. Indistinct features that indicate a transient meteoric precursor stage (isotope shifts, meteoric cements, circumgranular cracks, etc.) are present but their interpretation requires careful and detailed work. This feature is remarkable, as a series of relative sea-level falls with amplitudes of up to several tens of metres from the Early to Late Aptian boundary to the end of the Aptian are reported from the Middle East and elsewhere. Despite the palaeogeographic position of the study area in the tropical climate zone, evidence of deep-cutting karst features, characteristic for many long-term exposure surfaces worldwide is scarce. Acknowledging the fact that the modern world offers no genuine analogues for the Lower Aptian carbonate system in Oman, morphological similarities between actualistic, wave-eroded coastal terraces and the top Shu'aiba discontinuity are discussed critically. This discussion may imply that, during an exposure time of several million years, the top Shu'aiba discontinuity experienced repeated stages of shallow flooding and emergence, with each transgression removing portions of the underlying rock record. The data shown here exemplify the complexity of hiatal surfaces in epeiric-neritic carbonates and may serve as a case example for other major discontinuities. [ABSTRACT FROM AUTHOR]

Discusses the influence of glacial conditions on sedimentation in the Smalfjord Formation of northern Norway. Absence of evidence for coeval tectonism; Suggestion that there is no transition at the top of the Smalfjord Formation from deep-water and shallow-water environments; Subglacial tectonism and banded diamictite at Tarmfjord; Varangerfjord ice-scoured palaeovalley.

Discusses the influence of glacial conditions on sedimentation in the Smalfjord Formation of northern Norway. Suggestion that the striations should not be used as evidence for direct glacial influence on sedimentation of the overlying deposits; Argument that the occurrence of Neoproterozoic diamictites in widely separated regions in Norway cannot be used to support a glacial origin for the Smalfjord Formation.

Discusses the influence of glacial conditions on sedimentation in the Smalfjord Formation of northern Norway. Failure of direct sedimentological observations and comparisons to deliver unequivocal conclusions when deteremining whether diamictites are glacial or non-glacial; Suggestion that localized facies analysis must be harnessed together with other geological data on all scales.

Analyzes the limestones at the Middle Pleistocene Belmont Formation of Bermuda, which consists in part of beach-dune biocalcarenites which underwent intense contemporaneous cementation and diagenesis. Impact of fibrous isophacous cement on the beach deposits; How the previously deposited eolianites further inland were stabilized; Indication that phreatic meteoric diagenesis is more effective in cementing and altering the biocalcarenites.

Studies the regional and local variation in the mineralogy of the sandstones of the Eocene Tyee Formation, Oregon Coast Range. Differences in depositional conditions of sand grains; Assertion on the indecisiveness of the petrographic evidence for the origin of sandstone matrix; Three main lines of evidence supporting the notion that thin sections that the rock fragments in the low-matrix sample have altered mineralogically following burial.