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The study of two stratigraphic sections of the Tran Formation (upper Carnian–Norian) reveals the presence of a regressive carbonate beach succession. The interpretation of lower shoreface, upper shoreface, foreshore, and backshore deposits is based on field data, microfacies analysis and comparison with Holocene and ancient analogues. The various lower shoreface deposits include automicritic boundstones/cementstones which attest to a temporary establishment of the M factory most likely as an aftermath of the global Carnian Pluvial Episode. The upper shoreface grainstones show trough cross-bedding reflecting deposition by longshore currents. Grainstones/packstones of the foreshore subenvironment have several diagnostic features including low-angle plane lamination, keystone voids, eroded beachrock clasts, and well-sorted textures with marine phreatic and vadose cements. Their deposition was controlled by supply of granular material from the shoreface, incessant wave activity and daily tides, and early lithification protecting them from erosion and remobilization. The backshore strata comprise storm washover deposits (packstones, wackestones), mudstones deposited in marginal ponds, and agglutinated stromatolites (formed by trapping and binding in a tide-influenced setting). Some of the foreshore and backshore sediments were pedogenically modified, resulting in the formation of secondary matrix, root development, desiccation cracking, and grainification. Specific products of the early vadose alteration are laminoid fenestrae with crystal silt and diagenetic grainstones, packstones, and wackestones. The good preservation of the regressive beach succession was favored by late highstand progradation of the shoreline in a low accommodation setting.

The cored section of reservoir C, well 4 of the drilled five wells that penetrated three reservoirs A, B and C in “TOM” oil field, Eastern Niger Delta was analysed and described on the basis of lithofacies, sedimentary structures and trace fossil records by using core data and wireline log motifs, with the aim of carrying out thorough geological core analysis to interpret the depositional environment of the oil field. The lithofacies are sandstones with interbedded mudstones and siltstones, the dominant sedimentary structures are parallel to ripple cross laminations, hummocky and swaley cross stratifications, sandy hetherolitics, planar to low angle cross bedding with traces of Teichichnus and Ophiomorpha burrows. The gamma-ray log motifs were noted and used to further constrain the character of the sedimentary facies and depositional environment of the field. A tidal incised – fluvial dominated shallow marine (lower, middle, upper shoreface) comprises of tidal channel sands and tidal flat of the coastal shelf depositional setting in the marginal marine mega depositional environment had been inferred for the “TOM” field. Keywords: Shoreface, Reservoir, Lithofacies, Structures

The Upper Cretaceous sedimentary facies in areas around Inyi and environs, southeastern Nigeria comprises Ajali and Nsukka formations. A total of 19 outcrops were mapped and logged. Interpretation was based on field facies analysis and laboratory tests which include granulometric and X-ray diffraction (XRD) analyses of the rock samples. The objective of the study was to reconstruct the environment of deposition as well as understand the textural attributes of the sand size sediments for reservoir quality assessment. Eleven lithofacies: conglomeritic sandstone facies (Gc), cross-bedded sandstone facies (Scb), pebbly sandstone facies (Sp), bioturbated sandstone facies (Sb), heterolithic facies (Sht), claystone facies (Cl), coal facies (Co), bioturbated shale facies (Shb), laminated siltstone facies (Stl), muddy sandstone facies (Sm), and black carbonaceous shale facies (Shcb), were identified with four sub-facies occurring within low- to high-energy environment. These lithofacies were grouped into four facies association (FA1, FA2, FA3, and FA4). FA1 is dominantly conglomerates and pebbly sandstone deposited as channel/alluvial fan deposits. FA2 are deposits in a swamp or lagoon setting consisting of coal and black carbonaceous shale. FA3 is characterized by bioturbated sandstone, muddy sandstone, and heteroliths deposited in a lower shoreface setting. The cross-bedded sandstones and the heterolithic facies belong to the FA4 deposited in an upper shoreface setting. Sieve analysis results show sediments that are medium to coarse grained in sizes, poorly to moderately sorted, dominantly very negatively skewed to symmetrical and mainly mesokurtic. These granulometric attributes are typical of shallow marine deposits influenced by fluvial processes under low- to high-energy conditions. Result of XRD analysis show the presence of clay and non-clay minerals in the sediments, with quartz as the most dominant. Diagenetic processes which include compaction, cementation, precipitation, and dissolution influenced the reservoir quality of the sands. Compaction significantly reduced the primary porosity, and the sand-size grains (quartz) created a self-supporting framework while the clay minerals, mainly kaolinite and dickite, occluded the pores spaces. Dissolution removed some detrital grains leaving obvious indications of few interconnecting and independent pores and moderately to poorly sorted sands. These clay minerals bridge the pore throat connectivity and cause reduction in pore radii, and consequently reducing the reservoir potentials of the sands. However, the sediments could serve as potential hydrocarbon reservoirs especially for gas. The coal seams and the black carbonaceous shale facies can serve as the source or seal rocks whereas the sandstone, siltstone, and heteroliths are possible reservoir rocks of the petroleum system in the study area.

Accuracy of geological modeling and understanding of the controlling parameters in sedimentary systems evolution are challenges in both academy and industry. Uncertainty in the prediction of spatial and temporal facies distributions and difficulties in quantitative analysis of controlling parameters are current challenges. To increase geological model certainty and sedimentary process understanding, computational modeling has evolved exponentially during the last 50 years. In this study, 3D stratigraphic forward modeling technique is used to simulate an ancient transgressive barrier system of southern Brazil, deposited during the Lower Permian in the Parana Basin, upper part of the Rio Bonito Formation. In the study area, the depositional systems are part of a large transgressive cycle that includes fluvial-estuarine facies at the base and barrier-lagoon deposits (associated with the development of salt marshes) at the top. Throughout the region, offshore strata cover the barrier-lagoon facies. The simulation successfully represented the retrograde evolution of the coastal barrier system, with longshore currents as the main transport mechanism of sediments. The evolution of the barrier system started with upper shoreface deposits overlying the lagoon system facies in the south. Later, lower shoreface sediments covered upper shoreface deposits. Then, shoreline migration continued landward. Finally, offshore transition deposits covered all previous deposits. Simulations and tests of controlling parameters allowed an adjustment to actual thickness and lithologies up to 83%. These simulations allowed for the analysis of model sensitivity, in particular to the influence of parameters that control sedimentary evolution. The main controlling parameter was sediment supply (volume and composition), followed by time step. Initial bathymetry and sediment velocity had less of an impact.

The extent and distribution of benthic geologic habitats on the upper shoreface (from the shoreline extending offshore to > 10-m water depth) was mapped along the 33-km-long Rhode Island south shore (RISS) in 2015–2016 using a combination of high-resolution side-scan sonar, seismic reflection profiles, surface sediment samples, and underwater video imagery. Modern (Holocene) sediment is contained largely in the shoreface depositional platform (SDP), the constructional, seaward sloping portion of the upper shoreface extending from the intertidal beach, offshore. The SDP varies in thickness and width along the RISS, with a mean thickness of 0.7 m and a mean width of 260 m. Maximum thickness (

Integrated sedimentological and ichnological study of the gas-bearing, upper Middle Miocene strata in the southwestern Ulleung Basin has identified five main lithofacies, arranged in order from offshore and offshore transitional environments to coastal-plain channel settings. In each of repeated successions, the basal mudstone-dominated, offshore to offshore transitional facies are sharply overlain by upper shoreface sandstones that are, in turn, erosively overlain by distributary channel sandstones. In the open-marine environment, interbedded storm and interstorm deposits are predominant with sporadic flood-event beds containing a navichnia trace-fossil suite. Bioturbation style in this facies tends to reflect depositional energy variations, alternating between dwelling structures in the storm beds and feeding and grazing trace-fossil assemblages in the interstorm beds. In the channel deposits, flood-interflood couplets are commonly expressed as cross-bedded, almost non-bioturbated sandstones that alternate with bioturbated, tidally-formed, interbedded sandstone and mudstone. From this, the co-existence of storm-wave and tide-generated structures in the studied interval suggests that the depositional environment is a wave-dominated and tide-influenced deltaic setting, with the recorded tidal influence restricted to the channels, which have a higher level of heterogeneity because of tidal sedimentation during periods of low river discharge. Stratigraphically, the 400-m thick, upper Middle Miocene section shows an overall, coarsening-upward succession, representing 3rd-order falling-stage to lowstand deposits as a result of long-term basinal uplift. This succession can, in turn, be broken into four, 4th-order stratigraphic packages, each of which comprises a transgressive (T)-regressive (R) succession that is separated by a transgressive surface. These packages can be further subdivided into small-scale, upward-coarsening successions (5th-order stratigraphic packages of parasequence scale). Each small-scale succession is sharply overlain by offshore mudstone which reflects a rapid vertical facies transition, representing a marine flooding surface. Internally, each parasequence is characterized by a progradational facies succession wherein offshore mudstones are erosively overlain by upper-shoreface sandstones, forming sharp-based shoreface deposits that are likely to be produced during a forced regression, an interpretation supported by the presence of an omission trace-fossil suite on the erosion surface. In this context, the high-frequency parasequences represent short-term relative sea-level falls superimposed on the longer-term falling sea level due to a compressional tectonic regime.

The study deals with a large sand body (spit-bar) attached to the eastern tip of the Robberg Peninsula, Plettenberg Bay, South Africa. To date, the bar has prograded about 8 km beyond the tip of the peninsula. The bar top is predominantly composed of medium sand, the upper slope of fine sand, and the lower slope of fine muddy sand. Stratigraphically, the sedimentology thus documents an upward coarsening, calcareous quartz-arenitic depositional sequence. The spit-bar as a whole forms the eastern end of a sediment compartment that is clearly distinguishable from neighbouring compartments on the basis of its geomorphology, the textural characteristics of the sediment, and the distribution of sediment thicknesses. Aeolian overpass across the peninsula appears to have formed a fan-like sand deposit in its rear, which is perched upon the upper shoreface of the bay as suggested by the bathymetry to the north of the peninsula. It forms an integral part of the sediment body defining the spit-bar. The estimated volume of sand stored in the spit-bar amounts to 5.815 km3, of which 0.22 km3 is contributed by the aeolian overpass sand. The sediment sources of the spit-bar are located up to 100 km to the west, where a number of small rivers supply limited amounts of sediment to the sea and numerous coastal aeolianite ridges in the Wilderness embayment have been subject to erosion after becoming drowned in the course of the postglacial sea-level rise since about 12 ky BP. By contrast, the sediment volume in the adjacent compartment B to the north (Plettenberg Bay), which has been supplied by local rivers, amounts to only 0.127 km3. In a geological context, large sand bodies such as the Robberg spit-bar are excellent exploration models for hydrocarbons (oil and gas).

14 pages, 7 figures, 1 table, Ripples and small-scale bedforms are ubiquitous in shallow water environments under the combined action of currents and waves. Small scale processes linked to their formation and migration are interconnected with sediment transport at larger scales (e.g. tens of metres to kilometres), both resulting in and being affected by large scale sediment transport and geomorphological evolution. The lower shoreface provides a key link between coasts and continental shelves, but the contribution of ripples and small-scale bedforms to sediment transport in this region has yet to be fully addressed. This work presents a study of sediment dynamic processes on the lower shoreface in the presence of small-scale bedforms. Observations were made during the winter of 2017 on the lower shoreface of Perranporth Beach, which is in the south west of the UK and exposed to Atlantic waves. The analysis of morphological expressions and the variability of ripples under waves, currents and wave-current conditions are assessed. Ripple morphology and associated dynamics are analysed for their potential contribution to the exchange of sediment between the lower and the upper shoreface. In the present study it was observed that even though ripples were evolving depending on the wave-current forcing, little ripple migration was observed due to low wave skewness. The implication is that ripple migration and bedload transport are only a small contribution to onshore sediment transport under low to moderate energy conditions. However, during more energetic conditions, ripples were washed out and the wave skewness increased, resulting in onshore sediment transport under a sheet flow regime. This suggests that ripple formation and migration can have little impact on the cross-shore supply of sediment from the lower shoreface to the upper shoreface and that more energetic wave conditions are required to significantly transport sediment towards the beach, QG was supported by an FPI grant (ref. BES-2013-066261) from the Spanish Ministry of Economy and Competitiveness in the frame of the project FORMED (CGL2012-33989). QG was also supported by a mobility grant to develop short stays at the National Oceanography Centre, Liverpool (NOC-NERC) (ref: EEBB-I-17-11989) from the Spanish Ministry of Economy and Competitiveness. The authors wish to acknowledge funding from the Natural Environment Research Council to the BLUEcoast project (grant numbers NE/015894/1 and NE/015894/2). MEW was partially supported by Chilean Fondecyt project 11191077 and the National Research Center for Integrated Natural Disaster Management (CIGIDEN, ANID/FONDAP 15110017), With the institutional support of the‘ Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S)

A ~125 m thick shallowing-upward arenaceous succession from the Badalgarh Formation, Bayana basin, India provided the opportunity to document shelf to foreshore transition from a paleoproterozoic rift set-up. Process-based facies analysis allowed identification of 12 different shallow-marine facies types, grouped under four different facies associations namely (i) lower offshore or open shelf, (ii) upper offshore to distal lower shoreface, (iii) lower to middle shoreface and (iv) upper shoreface to foreshore. From unequivocal dominance of wave- and storm-generated features and fortuitous documentation of tide-generated structures in upper offshore, lower and middle shoreface settings, we infer a tide-influenced, wave-dominated coast at the Badalgarh Sea. From measurement of different vector attributes through the studied succession, we infer (i) near east–west orientation for the Badalgarh shoreline, (ii) storm deposits as products of shore-perpendicular return flow, and (iii) tidal peak flow at a high angle with the shoreline and confined in the upper offshore, lower and middle shoreface settings. A gradational transition from offshore to lower shoreface and, in turn, to middle and upper shoreface suggests accretionary character for the Badalgarh shoreface in a high-gradient rift setting. Overlying deep water (distal offshore) argillaceous marine strata, the arenaceous shallowing-upward Badalgarh succession is interpreted as a product of highstand systems tract (HST) constituted of stacked tens- to hundreds of meter-thick shallowing-upward depositional cycles. Since the abrupt shift in facies type (shallow to deep water) across the upper boundaries of depositional cycles is not unambiguous, we intend to assign these cycles as genetic stratigraphic cycles or T-R cycles over ‘parasequence’.

Existing barrier island facies models are largely based on modern observations. This approach highlights the heterogeneous and dynamic nature of barrier island systems, but it overlooks processes tied to geologic time scales, such as multi-directional motion, erosion, and reworking, and their expressions as preserved strata. Accordingly, this study uses characteristic outcrop expressions from paralic strata of the Upper Cretaceous Straight Cliffs Formation in southern Utah to update models for barrier island motion and preservation to include geologic time-scale processes. Results indicate that the key distinguishing facies and architectural elements of preserved barrier island systems have very little to do with “island” morphology as observed in modern systems. Four facies associations are used to describe and characterize these barrier island architectural elements. Barrier islands occur in association with backbarrier fill (FA1) and internally contain lower and upper shoreface (FA2), proximal upper shoreface (FA3), and tidal channel facies (FA4). Three main architectural elements (barrier island shorefaces, shoreface-dominated inlet fill, and channel-dominated inlet fill) occur independently or in combination to create stacked barrier island deposits. Barrier island shorefaces record progradation, while shoreface-dominated inlet fill records lateral migration, and channel-dominated inlet fill records aggradation within the tidal inlet. Barrier islands are bound by lagoons or estuaries and are distinguished from other shoreface deposits by their internal facies and outcrop geometry, association with backbarrier facies, and position within transgressive successions. Tidal processes, in particular, tidal inlet migration and reworking of the upper shoreface, also distinguish barrier island successions. In sum, this study expands barrier island facies models and provides new recognition criteria to account for the complex geometries of time-transgressive, preserved barrier island deposits.

Summary Carbon emission has been increasingly alarming due to higher industrial activities. In conjunction with a net zero carbon emission policy by 2050, research has been done to promote CO2 underground storage. The offshore Sarawak region had been explored throughout the decade to achieve an enhanced understanding of the basin. The offshore Sarawak Basin has promising storage characteristics which are displayed evidently from wells data and seismic lines. Cycle I and II portrays complex lithofacies which affect porosity and permeability. Cycle I and II analogous to the Nyalau Formation exhibits the lower and upper shoreface facies. The average storage depth is above 1000 m with a fairly warm sedimentary basin of a geothermal gradient >43°C. These conditions allow CO2 to be stored in a dense phase which will maximise the storage volume and reduce upward migration. The trapping of CO2 in these areas improved with intraformational seals of Setap Shale and Lower Cycle III as regional seals. The trapping mechanisms allow CO2 to migrate between pores and dissolve into formation water beneath the seal which is laterally extensive within the basin to prevent upward migration. The characteristics described above portrays good reservoir and trapping potential for the CO2 storage.

As is the case with many deltas in the world, the Po Delta (Italy) and its barrier systems have experienced severe modifications over the last century as a consequence of anthropogenic subsidence and river input decrease. The interruption of subsurface fluid withdrawals in the early 1960s created an opportunity to evaluate the effects of the subsequent subsidence decrease along the 11 km of beaches and 45 km of barrier islands of the Po Delta, and improve the understanding of coastal system response to relative sea level rise. To this aim, shoreline and bathymetric multi-decadal dataset were coupled with the local rate of subsidence and classified with a geomorphic - response approach. From 1954-78, a mean shoreline variation of −224 m (−9.34 m y−1) occurred under high rates of subsidence (14–43 mm y−1) with a diffuse process of landward barrier rollover (up to 1124 m), frequently associated with break-up. This phase is evidenced by the diffuse sinking of the shoreface (up to 4 m), the negative upper shoreface sediment budget and the parallel drowning of the cross-shore profiles highlighted by the 1968–2008 bathymetric dataset. Despite the loss of altimetry and shoreline retreat being almost irrecoverable, during the period from 1978 to 1996 and 1996 to 2014 barrier islands experienced a stabilisation in response to a decrease in the subsidence rates down to 6 mm y−1. The mean rates of shoreline changes (−0.25 and + 1.51 m y−1 respectively) are the results of different local behaviour with progressively dominant longshore processes and progradation at the most active fluvial branches. The most recent bathymetric data (2008–2014) confirm this reversal trend, both in the altimetry differences and in the upper shoreface sediment budget. This trend is at odds with signals from many of the world's deltas and represents an important issue for the present and future coastal management and adaptation plans.

The Macelj formation is an informal Eggenburgian-early Ottnangian lithostratigraphic unit that is established in the area of the Hrvatsko Zagorje Basin, which represented a marginal zone of the Early Miocene Central Paratethys Sea. Modern studies, as a part of the Geologic Map of the Republic of Croatia 1:50 000 project, yielded new data that improves the knowledge of the depositional and stratigraphic characteristics of the formation. The sedimentological research within this study was focused on the two older lithostratigraphic units of the Macelj formation: the Vučji Jarek member and the Čemernica member. The Vučji Jarek mb. is represented by three facies. The Facies of horizontally bedded sandstones is characterized by mostly medium-grained, moderately sorted sandstones that reflect deposition on the foreshore to the upper shoreface. The facies of horizontally and cross-bedded glauconitic sandstones is composed of fine- to coarsegrained, well-sorted sandstones that indicate foreshore to shoreface deposition under tidal influence. The Facies of horizontally and cross-bedded pyroclastics consists of tuff, pumice, lapilli and large blocks, showing a chaotic structure in places. Deposition occurred at the shoreface under tidal influence. The Čemernica mb. is represented by the Facies of structureless clayey-silty sands that are poorly sorted and bioturbated, and indicates deposition below the fairweather wavebase, in the offshore-transition zone. Deposits of the members include marine macro- and microfossil associations. K-Ar dating of separated glauconite mineral fractions yielded an early Eggenburgian age for the Vučji Jarek mb. glauconitic sandstones (19.2±0.64 Ma) which is in accordance with biostratigraphical analyses. Sedimentological characteristics of the Eggenburgian Macelj fm., especially those that reflect the tidal influence, fit the general characteristics of the Central Paratethys Sea in the Early Miocene.

Resumen: Las trazas de Dactyloidites ottoi, asociadas a facies de areniscas silíceas, de grano medio, limpias, con laminaciones paralelas planas y curvas y laminación inclinada HCS se desarrollaron en ambientes someros (upper shoreface), de la Formación Coris (Mioceno). Fueron condiciones de alta energía generadas por olas, tormentas, corrientes y mareas. Sedimentación episódica con eventos erosivos de alta energía por tormentas y depositación de baja energía con aporte de materia orgánica favorecieron el retrabajo del sedimento. Estos icnofósiles no son frecuentes en el registro sedimentario y no habían sido reportados en Costa Rica. Están constituidos por varios elementos elongados que salen radialmente de un conducto central y conforman series de galerías superpuestas en forma de abanico o roseta. Aunque no se conoce el productor, diferentes estudios coinciden en que es una traza de alimentación tipo fodicnia producida por un organismo vermiforme que forma parte de la icnofacies Cruziana. Abstract: Dactyloidites ottoi traces associated with medium grained, mature, siliceous sandstone facies, with planar and curved parallel lamination and HCS cross laminations were developed in shallow marine environments (upper shoreface) of the Coris Formation (Miocene). High-energy environmental conditions were caused by waves, storms, tides and currents. Episodic sedimentation with high-energy erosive events caused by storms alternating with low-energy deposition with organic matter input favored sediment rework by organisms. These ichnofossils are infrequent in the sedimentary record and they had not previously been reported in Costa Rica. They are constituted by elongated elements which radiate from a central shaft and create a series of rosetted or fan-shaped tiered galleries. The organism that created these structures is yet unknown, however, several studies coincide that it must have been a feeding fodichnia trace produced by a worm-like organism which is part of the Cruziana Icnofacies.

The lower shoreface provides the connection between the continental shelf and the shoreline via its onshore transition called the upper shoreface. Lower shorefaces are diverse, and range from bedrock-controlled, through sediment-starved to sediment-rich, siliciclastic, carbonate, low to high wave-energy, microtidal to macrotidal, and are variably affected by storm and wind-driven flows. The lower shoreface can be a repository for deposits of terrestrial origin, and a zone of active carbonate production. It can therefore be an important source of sediment for beaches, dunes, estuaries, and tidal basins. There has been progress in the ability to predict suspended sediment transport under non-breaking and shoaling waves across the lower shoreface. However, high-resolution measurement of sediment transport over unknown seabed configurations with unpredictable bed-level changes under hydrodynamic conditions that are unknown at the outset, and especially involving bedload transport, is still faced with significant challenges. Non-linear interactions between processes contributing to sediment transport render calculations and modelling of transport directions and magnitudes uncertain, and the spatial and temporal scales of transport are much larger than those of the upper shoreface. On the other hand, transport rates and morphological change may be much smaller on the lower shoreface compared to the upper shoreface. Another challenge is the upscaling of short-term measurements to explain the long-term morphological evolution of the lower shoreface. This limited understanding implies that current paradigms of lower shoreface dynamics based on morphological equilibrium and disequilibrium relative to the ocean-forcing conditions may be too simplistic, though possibly appropriate over long timescales (decades to millennia), and modelling work and prediction of change no more than exploratory. Over such long timescales, boundary conditions (sea level, wave climate) are likely to change. Making way forward on these issues is important for understanding the connectivity between the lower shoreface and beach recovery after major storm erosion, and for estimating coastal sediment budgets, short- to long-term coastal change and response to natural and anthropogenic perturbations. At geological timescales, the lower shoreface is a central element in tracking shoreline changes. Progress is needed in measuring sediment transport and upscaling to timescales compatible with lower shoreface change. It is also important to take advantage of on-going rapid progress in seabed and shallow stratigraphic mapping, bed-level changes, including remote-sensing approaches, for a better understanding of lower shoreface morphodynamics and sediment connectivity with the coast. This includes the now routine identification of large subaqueous bedforms, possibly ubiquitous features on the world's continental shelves, their mobility over time, and their potential link with the shoreline. The common relationship between fine sand, dissipative beaches and large aeolian dunes also poses the question of how fine sand is abundantly supplied from the lower shoreface, given the common perception that it is readily swept offshore on beaches. These multi-theme challenges need to be addressed in order to advance our understanding of the lower shoreface and its connectivity with the upper shoreface and beach.

An integrated study combining sedimentological and ichnological data has been conducted in the lower wave-dominated deposits of the Calafate Formation. The study aimed to assess the variation in fair-weather and storm processes, tidal flux, and the coast configuration to correctly constrain sedimentary dynamics in complex depositional systems. The wave-dominated deposits comprise foreshore to upper shoreface (FA1), middle to lower shoreface (FA2) and offshore-transition deposits (FA3) moderately affected by storms. In FA1, the most proximal strata contain Macaronichnus isp. and occur within the foreshore, while the upper shoreface shows an increased ichnodiversity associated with the occurrence of the archetypal Skolithos ichnofacies evidencing heightened energies of the upper shoreface. FA2 display a fair-weather community assigned to the proximal Cruziana ichnofacies that shows a wider range and variability of living strategies, and a storm-related community represented by opportunistic colonizers which produced burrows assigned to Ophiomorpha nodosa. The monospecific occurrence of Thalassinoides isp. at the top of FA2 in CC02P section is assigned to the Glossifungites ichnofacies, developed on a firmground and autogenic surface. The ichnoassemblage in FA3 is attributable to the transitional Skolithos-Cruziana ichnofacies, that exhibits a slightly reduced diversity of the fair-weather community and a sparse bioturbation. The distribution and the general characteristics of the ichnological assemblages are consistent with deposition in fully marine conditions. The bioturbation intensity, trace-fossil diversity, maximum penetration, and burrow size distributions indicate fully oxygenated and clear waters, normal-marine salinity conditions, abundance and accessibility of food, and continuous and moderate sedimentation. Nevertheless, the ichnological signature in FA3 is related to minor physico-chemical stress produced by strong tidal currents originated during the southward expansion of the Magallanes embayment. Fil: Odino Barreto, Andrea Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: Richiano, Sebastián Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; Argentina Fil: Gingras, Murray. University of Alberta; Canadá Fil: Poire, Daniel Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina

Dactyloidites ottoi traces associated with medium grained, mature, siliceous sandstone facies, with planar and curved parallel lamination and HCS cross laminations were developed in shallow marine environments (upper shoreface) of the Coris Formation (Miocene). High-energy environmental conditions were caused by waves, storms, tides and currents. Episodic sedimentation with high-energy erosive events caused by storms alternating with low-energy deposition with organic matter input favored sediment rework by organisms. These ichnofossils are infrequent in the sedimentary record and they had not previously been reported in Costa Rica. They are constituted by elongated elements which radiate from a central shaft and create a series of rosetted or fan-shaped tiered galleries. The organism that created these structures is yet unknown, however, several studies coincide that it must have been a feeding fodichnia trace produced by a worm-like organism which is part of the Cruziana Icnofacies. Las trazas de Dactyloidites ottoi, asociadas a facies de areniscas silíceas, de grano medio, limpias, con laminaciones paralelas planas y curvas y laminación inclinada HCS se desarrollaron en ambientes someros (upper shoreface), de la Formación Coris (Mioceno). Fueron condiciones de alta energía generadas por olas, tormentas, corrientes y mareas. Sedimentación episódica con eventos erosivos de alta energía por tormentas y depositación de baja energía con aporte de materia orgánica favorecieron el retrabajo del sedimento. Estos icnofósiles no son frecuentes en el registro sedimentario y no habían sido reportados en Costa Rica. Están constituidos por varios elementos elongados que salen radialmente de un conducto central y conforman series de galerías superpuestas en forma de abanico o roseta. Aunque no se conoce el productor, diferentes estudios coinciden en que es una traza de alimentación tipo fodicnia producida por un organismo vermiforme que forma parte de la icnofacies Cruziana.

Undichna quadrisulcata isp. nov. is described from the Eocene of Spitsbergen, where it occurs together with xiphosuran (horseshoe crabs) traces in upper shoreface to foreshore deltaic sandstone. Th...

The Kunzam La (Parahio) Formation along the Shian section of the Pin Valley was previously interpreted as containing Ediacaran–Cambrian boundary trace fossils, but re-examination of the Shian section shows that the oldest part of the section belongs to the late part of Cambrian Series 2, Stage 4, which contradicts the previous interpretation. The trace fossil assemblage comprises ?Arborichnus isp., Archaeonassa isp., Diplichnites isp., Hormosiroidea isp., Monomorphichnus lineatus, Bergaueria aff. langi, Palaeophycus tubularis, Rusophycus isp., and Treptichnus-like fossils that occur stratigraphically below the Oryctocephalus indicus biozone (Series 3, Stage 5) along the section and belong to the late part of Series 2, Stage 4. Sedimentary structures recorded along the section include hummocky cross-stratification (HCS) with deeply bioturbated tops, trough- and low-angle cross stratification, ball and pillow structures and climbing-ripple cross stratification. Integrated ichnofabric and sedimentological data suggest a storm-dominated, lower to upper shoreface shallow-marine environment of deposition.

Well log and core data were used to carry out detailed facies, sequence stratigraphic, and petrophysical analyses of the “Iota field” in the onshore Niger Delta Basin. The aim was to recognize facies distribution, environments of deposition, stratigraphic framework, reservoir continuity, and property distribution for better understanding of reservoir characteristics across the field. Sedimentological evidence reveals the occurrence of fifteen lithofacies, which were further classified into eight facies associations. The facies associations depict deposition in the offshore, offshore transition, lower shoreface, upper shoreface, estuarine channel, tidal channel, and fluvial channel environments. Sequence stratigraphic analysis reveals the occurrence of three maximum flooding surfaces and three sequence boundaries, which reflect series of transgressive and regressive episodes during the Serravallian–Tortonian age. Two depositional sequences comprising lowstand system tract, transgressive system tract, and highstand system tract packages were recognized. The sand and shale of the fluvial, tidal, estuarine, shoreface and offshore deposits, constitute the reservoir and seal/source rock packages. Correlation indicates that the reservoir packages have good lateral continuity, except where channel incision has occurred. Petrophysical analysis shows that the reservoir units have fair-to-good porosity and good- to-excellent net-to-gross qualities. Dominance of oil-bearing zones were detected at shallow to deeper interval at the northern section of the study area, with few gas-bearing intervals occurring at the intermediate intervals of the southern section. Overall, integrated analytical approach has provided more insight into the facies and reservoir quality distribution, thus reducing subsurface reservoir uncertainties.

Based on a methodic sedimentological analysis, the Late Jurassic (Oxfordian) Curtis Formation unravels the intricate facies variability which occurs in a tide-dominated, fluvially starved, low-gradient, semi-enclosed epicontinental basin. This unit crops out in east-central Utah, between the eolian deposits of the underlying Middle Jurassic (Callovian) Entrada Sandstone, from which it is separated by the J-3 unconformity, and the conformable overlying supratidal Summerville Formation of Oxfordian age. A high-resolution sedimentary analysis of the succession led to the recognition of eight facies associations (FA) with six sub-facies associa¬tions. Based on the specific three-dimensional arrangement of these eight facies associations, it is proposed to separate the Curtis Formation into three sub-units: the lower, middle and upper Curtis. The J-3 unconformity defines the base of the lower Curtis, which consists of upper shoreface to beach deposits (FA 2), mud-domi¬nated (FA 3a) and sand-dominated heterolithic subtidal flat (FA 3b), sand-rich sub- to supratidal flat (FA 4a) and correlative tidal channel infill (FA 4c). It is capped by the middle Curtis, which coincides with the sub- to intertidal channel-dune-flat complex of FA 5, and its lower boundary corresponds to a transgressive surface of regional extent, identified as the Major Transgressive Surface (MTS). This surface suggests a potential correla¬tion between the middle and the upper Curtis and the neighboring Todilto Member of the Wanakah Forma¬tion or Todilto Formation. The upper Curtis consists of the heterolithic upper sub- to intertidal flat (FA 6) and coastal dry eolian dunes belonging to the Moab Member of the Curtis Formation (FA 7), and it conformably overlies the middle Curtis. The spatial distribution of these sub-units supports the distinction of three different sectors across the study area: sector 1 in the north, sector 2 in the south-southwest, and sector 3 in the east. In sector 1, the Curtis For¬mation is represented by its three sub-units, whereas sector 2 is dominated by the middle and upper Curtis, and sector 3 encompasses the extent of the Moab Member of the Curtis Formation. This study also highlights the composite nature of the J-3 unconformity, which was impacted by various processes occurring before the Curtis Formation was deposited, as well as during the development of the lower and middle Curtis. Local collapse features within the lower and middle Curtis are linked to sand fluid over¬pressure within a remobilized sandy substratum, potentially triggered by seismic activity. Furthermore, the occurrence of a sub-regional angular relationship between the middle Curtis and substratum implies that the area of study was impacted by a regional deformational event during the Late Jurassic, before the deposition of the middle Curtis.

The Barremian–Aptian Morro do Chaves Formation, NE Brazil, was deposited in lacustrine environments during the rifting between the African and South American plates. This formation contains shell beds (coquinas) interbedded with mudstone and sandstone deposits. Shell concentrations may be used to identify paleontological and paleoenvironmental data that allow to interpret the depositional energy, paleoenvironmental conditions and the accumulation history of the formation. The following features of the shell beds were analyzed: (i) taphonomic aspects (sorting, fragmentation, abrasion, rounding and orientation of the shells), (ii) sedimentological aspects (grain packing, abundance of shells, type of matrix and sedimentary structures) and (iii) stratigraphic aspects (bed dimension and shape, bounding surfaces). Two siliciclastic lithofacies (clay mudstones with mud cracks and laminated sandy mudstones) and four carbonate lithofacies (wackestones, packstones, grainstones and rudstones) are described based on the textural features. The carbonate facies were successively divided into six taphofacies (T1 to T6) with the help of an artificial neural Self-Organizing Map (SOM) and evaluated by non-metric multidimensional scaling (NMDS), based on taphonomic features of the carbonate lithofacies. Taphofacies and lithofacies formed at lacustrine margins. Clay mudstone layers with mud cracks and without shells fragments are interpreted as distal parts of alluvial fans or fluvial distributary systems at the edges of the lake system. Rudstones and packstones (taphofacies T1, T2, and T3) with fragmented and oriented shells, wave ripples and horizontal lamination correspond to upper shoreface deposits. Rudstones, packstones and wackestones (taphofacies T4, T5 and T6) that display shells with low signs of fragmentation and abrasion and laminated clay mudstone are interpreted as lower shoreface deposits. A depositional model of the coquinas of the Morro do Chaves Formation is proposed based on the characteristics and distribution of the taphofacies. Moreover, the use of an embedded Markov Chain enabled the relation of the different upper and lower shorefaces in a preferential sequence of deposits of shallowing- and deepening-upward cycles.

The study of the upper Lower to Middle Jurassic Badamu Formation in SE of central Iran represents the first report of Jurassic ooidal ironstone in Iran and exhibits a record of ferruginous radial ooid-dominated ironstone. The studies showed that this chamosite or ferric oxide-chamosite type ooidal ironstone is similar to Minette-type ironstones. A shoreface zone in an epeiric or epicontinental sea is proposed for formation and accumulation of the ferruginous ooids and the ooidal ironstone. Fe derived from lateritic weathering has been transported into the shoreface zone via a fluvial current during the synsedimentary formation of the ooidal ironstone. During the periods with moderate to lower-energy or weakly agitated and quiet environmental conditions, suspended ferruginous small radial ooids and Fe were increased in the lower shoreface subzone. Higher environmental energy resulted in the development of large concentric ooids and limited distribution of Fe in the upper shoreface subzone. Higher environmental energy also prevented the development of radial ooids and restricted Fe precipitation on carbonate ooids. Variations in environmental energy in the middle shoreface subzone were unfavorable for increasing ferruginous ooids and Fe in the environment. Although, short term periods with weakly agitated and quiet or moderate to lower-energy conditions could had been existed in the middle shoreface subzone but precipitation of Fe on a few small radial ooids was allowed. Environmental energy in the shoreface zone was the major factor controlling precipitation of Fe (especially suspended river Fe loads) on the ooids. However, precipitation of dissolved Fe could have been related to oxidizing conditions in the environment. Also, the probable presence of Fe oxidizing bacteria in the cortexes of the ferruginous small radial ooids indicates that bacteria could have possibly contributed to precipitation of Fe on the ooids in a calm environment.

The study documents soft-sediment deformation structures (SSDSs) in the lacustrine Dongying Depression, a Paleogene synrift basin located in the southeastern corner of the Bohai Bay Basin, East China. The focus of this study is the lower part of the upper 4th member of the Eocene Shahejie Formation (Es4U), characterized by littoral to sublittoral deposits in the southwestern Dongying Depression. Nine lithofacies are grouped into the upper shoreface facies associations (FA1-1), lower shoreface facies associations (FA1-2), and sublittoral facies associations (FA2). Fine-grained calcareous sandstone was mainly deposited in FA1-1, with thinly alternating calcareous mudstone and siltstone or sandstone in FA1-2, while deposition in FA2 was dominated by mudstone, containing sediment gravity flow deposits. The SSDSs widely encountered in the lower Es4U can be classified into seven categories: (1) load structures, (2) water-escape structures, (3) folds and convolute lamination, (4) sediment-injection structures, (5) microfaults, (6) autoclastic breccias, and (7) slumps. Detailed observations of SSDSs from cores indicate liquefaction and fluidization as the main deformation mechanisms in the sands and muds. Moreover, rupturing of cohesive deposits also contributes to the soft-sediment deformation. The types and morphologies of the SSDSs are closely related to the rheologies of the sediments (e.g., the sand content), influenced by the facies that determine the lithologies and stratigraphic stacking patterns. Except for some deformation structures related to subaqueous sediment gravity flows (e.g., muddy debrite flows and slumps), most SSDSs are ascribed to rift-related seismicity due to the activity of the adjacent synsedimentary faults when the Dongying Depression underwent quick subsidence during the Eocene.

Studies on the environmental dynamics of high energy beach systems have to deal with factors as diverse as wave energy, coastal currents and tidal amplitude. Their interaction produces complex and often poorly understood sedimentary architectures. As a rule, the results achieved do not allow us to understand the depositional architectures associated with each of these processes. In this article, we analyze a high-energy beach system describing geometries, textures, paleocurrents, ichnological associations and taphonomic aspects seeking to define the associated environmental parameters. Detailed analyses of sedimentary facies, and analyses of paleocurrents, ichnological and taphonomic associations were performed in a high resolution sequence stratigraphy. The integrated analyses demonstrate the evolution of a high-energy beach system with a general north-south direction in a meso- to macrotidal regime, built by waves from the northwest, generating longshore currents to the south. A subordinate pattern, with waves coming from the southeast, generating longshore currents to the north, was also interpreted. Due to the high wave energy, evidence of tide action is sporadic, but the wide dominance of upper shoreface deposits with low angle dips, indicating an extension in the continent-offshore section, are compatible with a meso- to macrotidal setting. Taphonomic analysis shows that skeletons of marine invertebrates and vertebrates were significantly reworked and redistributed by strong wave action and longshore currents marking high energy events related to scour surfaces. Changes in the pattern of ichnofauna and bioturbation intensity are associated with variations in environmental energy and probably in salinity. The ichnological data helps to indicate progressive environmental stress towards the Cretaceous/Paleogene (K/Pg) boundary. Paleocurrent data, measured in trough cross-bedding of the upper shoreface deposits, suggest a complex atmospheric circulation pattern and water circulation of an inland sea. The resultant climatic pattern is compatible with modern atmospheric circulation at a similar latitude. The excellent exposure and abundant fossil records at K-Pg interval make this region an important source for studies of environmental dynamics and their interaction with biota at middle-high latitudes.

The “X Well” is located in the Salawati Basin which is part of Western Papua. The interval of study is the Klasaman Formation that is characterized by thick sediment intercalated sandstones and shales. The movement of Sorong Fault strongly controlled the sedimentation of this formation. This study is very important to give a contribution for developing exploration prospect by predicting reservoir distribution since localized facies change may mark the distribution of sandstones. The current study aims: 1) to define the age of Klasaman Formation; 2) to define the vertical facies; 3) to define the sequence stratigraphy; and 4) to predict the lateral change of facies. Five nannofossil datum planes are found throughout the interval and cover the age Late Miocene to Early Pliocene. LO Sphenolithus abies points the age 3.65 Ma, LO Reticulofenestra pseudoumbilicus points the age 3.79 Ma, FO Pseudoemiliania lacunosa points the age 4 Ma, LO Discoaster quinqueramus and LO Discoaster berrgrenii point the age 5.59 Ma and Top of small Reticulofenestra Interval points the age 7.167 Ma. They define the NN11 up to NN16 Martini’s zonation. The age of Klasaman Formation is known as the uppermost Late Miocene to the Early Pliocene. Four facies can be identified, namely Upper Shoreface, Lower Shoreface, Offshore Transition and Offshore. The upper shoreface facies is characterized by thick and clean sandstones, about 2.41 - 20.64 meters thick, while the lower shoreface facies consists of predominantly very fine to fine-grained sandstones intercalated by siltstones and claystones. The offshore transition facies is marked by thick claystones and siltstones intercalated with thin sandstones, whilst the offshore facies is marked by thick laminated claystones. Nine Parasequences 4th order can be identified within study interval, namely Progradational Parasequence-1 to 2, Retrogradational Parasequence-3, Progradational Parasequence-4 to 6, Retrogradational Parasequence-7 to 9. They are bounded by Sequence Boundary-1 to 8. The upper shoreface sandstones of Parasequence-4 to 9 can be potential reservoir rocks in the Klasaman Formation since the sandstones are very thick and clean. The sediments of Klasaman Formation have been sourced from elevated highland in the northeast area, so the upper shoreface sandstones have changed become the offshore claystones from northeast to southwest. High sedimentation rate and rapid subsidence of the basin mark the deposition of Klasaman Formation especially during the deposition of Parasequence-6 to 9 as a result of Sorong Fault tectonics.

The Rio Del Rey basin is a prolific petroleum field on the Continental margin of the gulf of Guinea and is one of the major producers in the gulf. The study was carried out using Schlumberger Petrel and Synergy Interactive Petrophysics software for the sequence stratigraphy and petrophysical analysis to study the depositional setting of the Rio Del Rey Basin, using Well Log Data. Five sequence boundaries, five Transgressive Surfaces and four Maximum Flooding Surfaces were identified from wireline log. The progradation of sediments is characterised by a number of stacked sequences deposited in a coastal complex, with offshore, shoreface, beach and tidal deposits. Sequence one contains mostly Lower shoreface deposits of fine to very fine laminated sediments. In sequence two there is, an increase proportion of upper shoreface deposits. Sequence three is dominated by upper shoreface and distributary channels deposits with a concomitant reduction of lower shoreface deposits while sequence four and five contain mostly stack distributary channels and beach deposits. The study has aided the identification and interpretation of two gas bearing and two oil bearing zones in the three wells based on hydrocarbon-typing using the sonic-resistivity logcombination. The total and effective porosities of the reservoirs range from 20% to 31% and 15% to 31% respectively, indicating that the reservoirs have very good porosities. The ratio of the net to gross thickness of the reservoirs is as high as 0.83. The water saturation values of the reservoirs ranges from 11% - 80%. The results of the petrophysical investigation show that the sand formations have good reservoir properties. The vertical facies succession records a migration/translation of laterally linked depositional environment, controlling reservoir properties like geometry, heterogeneity, porosity and permeability.

Oolitic ironstones are widely distributed in South China, particularly in Middle and Upper Devonian strata, and are referred to as Ningxiang-type iron deposits. The hybrid siliciclastic-carbonate deposits of the Lower Devonian Yangmaba Formation iron-enriched interval (dominated by hematite ooids and chamosite ooids) are recognized in the Shigouli section of the Longmenshan area, Sichuan Basin. The Yangmaba Formation ironstones differ from other Devonian Ningxiang-type oolitic ironstones: The Ninxiang-type ironstone deposits are commonly interpreted to have been deposited in a narrow coastal zone or inland restricted bays and lagoons with clastic and carbonate sedimentary sequences; by contrast, the studied oolitic ironstones are interpreted to have been deposited in a shoreface zone to inner shelf based upon field and petrographic investigations. Our study shows that this oolitic ironstone consists of dominantly hematite ooids and chamosite ooids. Major element and trace element discrimination diagrams, PAAS (Post-Archaean average Australian sedimentary rock) normalized REE (Rear earth element) patterns, and positive Ce/Ce* anomalies show evidence of a hydrogenous origin. The weathering of adjacent terrestrial rocks from the formation of the palaeo-land surface is interpreted to be the main Fe source for the oolitic ironstones. Environmental energy and redox conditions are the important factors controlling ironstone formation and distribution of the hybrid deposits of the Yangmaba Formation in the Shigouli section of the Longmenshan area. Oolitic ironstones formed in oxidizing conditions of the upper shoreface zone include the carbonate concentric ooids with slightly hematite ooids occurring in higher energy upper oxidizing shoreface subzone, moderately hematite concentric ooids deposited in middle oxidizing shoreface subzone of fluctuant environmental energy, and hematite ooids present in lower oxidizing shoreface subzone of lower-energy conditions or weakly agitated environment. The chamosite concentric ooids and superficial ooids formed in reducing conditions of the lower shoreface and upper offshore transition. The former occurred in upper reducing shoreface subzone near the fair weather wave base, and the chamosite superficial ooids were deposited in lower reducing shoreface subzone and upper offshore transition that was affected by episodic high energy events.

On the basis of distinct lithologic features such as composition, grain size, bedding characteristics and sedimentary structures, six facies were identified in Callovian to Oxfordian rocks exposed southwest of Bhuj, Kachchh. They are interbedded calcareous shale-siltstone (ICSSF), limestone (LF), ferruginous sandstone (FerSF), felspathic sandstone (FelSF), grey shale (GSF) and oolitic limestone (OLF) facies. The rich and highly diversified trace fossils reveal a wide range of animal behaviours represented by dwelling, feeding, crawling and resting structures. Horizontal feeding structures are found abundantly in all lithofacies indicating low wave and current energy and deposition of poorly sorted muddy to sandy sediments. A few coarse layers containing Arenicolites, Ophiomorpha and Skolithos indicate the presence of opportunistic animals (due to their first appearance under harsh conditions) under -intermittently moderate wave and current energy or storm wave conditions (due to coarse grain size and dominance/presence of only vertical trace fossils) in the shoreface zone. Taenidium occurs mainly in the lower shoreface to transitional zone suggesting low to moderate energy conditions. Thalassinoides occurs in middle to lower shoreface settings under relatively low-energy conditions. Zoophycos represents offshore environment, where it occupies the deepest bioturbation levels. The characteristic lithofacies and assemblages of trace fossils in the rocks of the Chari/Jumara Formation indicate a depositional environment fluctuating from the upper shoreface to offshore zone.

The Kaimiro Formation is an early to middle Eocene, NE-SW trending reservoir fairway in Taranaki Basin, and comprises a range of coastal plain through to shallow marine facies. A time of regional transgression is observed across the Paleocene–Eocene transition, which is linked to a general global warming trend and to regional thermal relaxation-related subsidence in New Zealand. The earliest Eocene transgressive deposits pass upwards into a series of cyclically stacked packages, interpreted as 3rd and 4th order sequences. Maximum regression occurred within the early Eocene and was followed by punctuated retrogradational stacking patterns associated with shoreline retreat and subsequent regional transgression in the middle Eocene. The Kaimiro Formation is considered a good reservoir target along most of the reservoir fairway, which can largely be attributed to a consistently quartz-rich, lithic-poor composition and reasonably coarse sand grain size. Correlations demonstrate that within the early Eocene the main reservoir facies are channel-fill sandstones overlying candidate sequence boundaries in paleoenvironmentally landward (proximal) settings, and upper shoreface/shoreline sandstones in relatively basinward (distal) settings. Middle Eocene reservoir facies are not represented in distal wells due to overall transgression at this time, yet they form a significant target in more proximal well locations, particularly on the Taranaki Peninsula. Depositional facies is one of the principal controls on sandstone reservoir quality. However, while reservoir facies have been proven along the length of the reservoir fairway, it is evident that diagenesis has significantly impacted sandstone quality. Relatively poor reservoir properties are predicted for deeply buried parts of the basin (maximum burial >4.5 km) due to severe compaction and relatively abundant authigenic quartz and illite. In contrast, good reservoir properties are locally represented in reservoir facies where present-day burial depths are These results illustrate how an interdisciplinary approach to regional reservoir characterisation are used to help reduce risk during prospect evaluation. Assessment of both reservoir distribution and quality is necessary and can be undertaken through integrated studies of facies, sequence stratigraphy, burial modelling and petrography.

Many ancient carbonate strata represent deposition on gently dipping ramp systems, yet processes and patterns of carbonate accumulations of modern carbonate ramps are not as extensively studied as those on modern isolated platforms and rimmed shelves. To better understand controls on sediment accumulations of the shallowest parts of tropical carbonate ramp systems, this study investigates geomorphology, sediment, and organic-matter abundance on the nearshore areas of the Holocene ramp system on the northwestern Yucatan Shelf, Mexico. Currents generated by the day-to-day easterly trade winds, and larger waves caused by winter cold fronts, have the net effect of transporting sediment and upwelled nutrient-rich (occasionally in excess of 5 mg/m 3 , eutrophic to hypertrophic) and cooler (∼ 16–20°C) water southward. The upper shoreface includes shore-parallel belts of mollusk- and Halimeda -rich muddy sand to gravel. Longshore sediment transport along the coast forms barrier-island spits of molluscan coquina beach ridges which have prograded southward and westward. The islands in turn act as barriers to form protected lagoons that accumulate ubiquitous fine sediment. A broad supratidal to freshwater marsh landward of the lagoons includes dominantly fine-grained carbonate sediment. Across the area, mollusks are the primary sediment contributors, although Halimeda is locally ubiquitous offshore. Barnacles, benthic foraminifera, sponges, bryozoans, and serpulid worm tubes dominate the remainder of carbonate sediment producers, although echinoderms and planktonic forams are present as well. Corals are notably absent, as are peloids and ooids. Biosiliceous organisms (diatoms, sponge spicules, dinoflagellates) contribute up to 20% of sediment throughout the shoreface and lagoon, and the greater part of carbonate mud is calcitic. This assemblage, which includes many biota of the heterozoan association, is interpreted to be related to upwelled cool nutrient-rich water, although local freshwater springs may provide nutrients in the lagoons. The results of this study illustrate the roles of energy level, sea-surface temperature, upwelled nutrient-rich waters, and possibly freshwater mixing on the geomorphology, biota, and sedimentology of the nearshore parts of this Holocene ramp system. The insights provide an actualistic model for sedimentological character and depositional heterogeneity of shoreface regions of ancient carbonate ramps influenced by upwelling.

This study is a contribution to the understanding of the depositional environment and reservoir architecture of the “Bruks Field,” Niger Delta, Nigeria. The objective is to use sequence stratigraphy and petrophysical evaluation in characterizing the reservoirs encountered in the study area. Well logs from six wells (B001, B002, B003, B009, B010 and B012-ST); biofacies data from wells B001 and B002; and a 3D seismic volume were analyzed to understand the spatial and temporal trends of reservoir sandstones, the environments of deposition, petrophysical properties of the F-sandstone and fault patterns on the structural map of the field. Log correlations show a considerable thickness of sands marked as fluvial. Results also show that the reservoirs are of foreshore, upper shoreface, lower shoreface, tidal channel and channel sands, which were deposited in a shallow marine setting. Two depositional sequences SEQ1 and SEQ2 were delineated with maximum flooding surfaces (MFS) 10.4 and 8.6 Ma, respectively. The depositional sequences are bounded with sequence boundaries (SB) dated 10.6, 10.36 and 7.4 Ma. The F-sand reservoir has an average net to gross thickness of 0.55, effective porosity of 0.29 v/v, permeability of 2506 mD and water saturation of 0.14 v/v. These values depict good reservoir quality, though the sand is deposited in tidal channels with the presence of heteroliths. The delineated faults composed of mainly growth faults, listric fault, antithetic and synthetic faults that formed the hydrocarbon traps for the F-sand.

The Salton Sea is a hypersaline, closed lake system in southern California, USA. Episodic fish kills led to bloating and floating fish bodies that were driven onto the shoreline by wind shear. The documented taphonomic destruction of the stranded fish carcasses includes the distribution of the fish parts after desiccation and disarticulation mainly by wave-induced transport with possible minor component of wind transport on the upper shoreface. Carcass decay is divided into five taphonomic categories 1 through 5. Category 1 represents whole pliable fish, recently washed onto the shoreline while category 5 incorporates longer-term destruction into ultimately single, isolated skeletal elements. High water, strand line deposits are delineated by the presence of categories 3 through 5 mixtures. The general trend, in 2012 was observed to be considerable bone disarticulation away from the shoreline because categories 1 and 2 were present in the swash zone; the influx of fresh fish carcasses recharged the shoreline. During 2013, the absence of new 1 and 2 categories arriving to the shoreline enhanced wave action to further break down categories 3 and 4 ultimately into category 5. In addition, isolated bone elements segregate according to density differences, typically on low-gradient beaches. Wave and wave-induced current action coupled with beach topography controls distribution of the various fish bones. As an actualistic model, the Salton Sea implies that shore-parallel complete to partial fish carcass concentrations are more shoreward and isolated skeletal elements more distal.

Bedforms and resulting sedimentary structures of interpreted upper-flow-regime origin are fairly common in various ancient and modern depositional settings, yet outcrop examples of shallow-water strata dominated by sedimentary structures arising from such flow conditions are rarely documented. This outcrop-based study presents the first detailed analysis of mid-Pleistocene beachface-shoreface strata containing sedimentary structures interpreted to have been formed by storm-generated backwash flows during the transition in flow regime from supercritical to subcritical. Here we propose that moving down the steep beachface, backwash flows rapidly accelerated and became thinner, experienced abrupt deceleration and flow thickening passing through an erosional hydraulic jump in the trough at the toe of the beachface, and then waned to thicker and subcritical conditions just downflow of the hydraulic jump. In this frame, landward-dipping backset laminae deposited on the downflow side of the trough evolved into thinner, upper-stage plane-parallel laminae further downstream. The transition from the proximal to the distal upper shoreface records a significant increase of preserved wave ripples and burrowed intervals, in concert with a progressive decrease in thickness and grain-size of individual sets of plane-parallel laminae and increase of gravel-filled gutter casts.

The concept of the Tommotian Regional Stage of the Siberian Platform has been closely linked to the idea of the ‘Cambrian Explosion’ of animals and protists when the entire Earth system shifted rapidly into Phanerozoic mode. We conducted a multidisciplinary study of an informal ‘synstratotype’ of the lower Tommotian boundary in the upper Mattaia Formation, Kessyusa Group in the Olenek Uplift, NE of the Siberian Platform. The Mattaia Formation characterizes an upper shoreface to inner-shelf depositional setting and provides important faunal ties and correlation with carbonate-dominated and aliminosiliciclastic open-shelf areas. A section of the upper Mattaia Formation at Boroulakh, Olenek River is suggested here as a model for the Global Boundary Stratotype Section and Point for the base of the Cambrian Stage 2. This level contains the lowermost occurrence of the cosmopolitan fossil helcionelloid mollusc Aldanella attleborensis. Section global markers near the base of the stage include a positive excursion of δ13C values reaching +5.4‰, a U–Pb zircon date of 529.7 ± 0.3 Ma, massive appearance of diverse small skeletal fossils (including Watsonella crosbyi), a sudden increase in diversity and abundance of trace fossils, as well as a conspicuous increase in depth and intensity of bioturbation. Coincidently, it is this level that has always been regarded as the lower Tommotian boundary on the Olenek Uplift.

The Troll Field in the Norwegian North Sea is one of the largest offshore gas fields in the world. Its western part contains a thin but exploitable oil leg (11–26 m) below the thick gas column, with the majority of the oil located in the late Jurassic Sognefjord Formation. The reservoir geology of the Troll Field was discussed in a few papers prior to production start-up in 1995, but a comprehensive account of the geological model of the Late Callovian – Late Oxfordian Sognefjord Formation has not as yet been published. The present paper reviews the depositional setting and architecture of this reservoir unit based on integration of results from disciplines such as sedimentology, seismic data analysis and stratigraphy. The Troll West reservoir formed on the edge of the Horda Platform during the Late Jurassic rift event; it consists of numerous stacked and generally offlapping sandstone units with intervening finer-grained deposits. The reservoir succession contains three composite sequences, of which the lower two belong to the Sognefjord Formation and the upper one is part of the Draupne Formation. Within this framework, five basic sequences and fifteen reservoir zones occur at the systems tract scale. The lower to middle parts of the studied succession reflect southwestwards growth and decay of a coastal spit system flanked to the east by a tidal backbasin. Brackish water facies have been identified in the eastern parts of the field through the use of detailed palynology. The extensive well database (including 15 cored production wells) and the high quality of the seismic data in the Troll area provide a unique opportunity to gain insight into the evolution of such a major spit-backbasin to tide-dominated deltaic system. A typical spit/strandplain progradation episode results in a clinoform succession comprising bioturbated sands of offshore transition origin overlain by lower shoreface sandstones which pass upward into clean, generally coarser-grained sands of upper shoreface and foreshore origin. The bases of such regressive sandbodies are often sharp, due to rapid facies translations during forced regression, but they may also be characterized by up to 40 m thick coarsening-upwards successions containing alternating siltstones and sandy event-beds generated by storm winnowing of the spit platform. Eastwards, these shallow-marine sandstone units finger into heterogeneous coastal plain deposits. On seismic data, this lateral transition is portrayed by the change from clinoform units in the west to undulatory seismic patterns in the east, as seen on maps based on classification of trace shape. A change in coastal morphology from wave- to tide-dominated took place in the Troll West area in the Late Oxfordian, perhaps related to an increase in tidal range. In the tidal facies tract, heterolithic inshore deposits formed in tidal channels and flats are replaced, in a seaward direction, by more sand-dominated high-energy tidal deposits such as mouth-bars and sand-ridge complexes. Further seawards, muddy shelf or prodelta deposits similar to those found in the wave-dominated facies tract are seen. In the Kimmeridgian, relative sea-level rise and eastward tilting of the Horda Platform caused reworking of the upper part of the Sognefjord Formation and localized hanging-wall shoreline sands formed as the uppermost reservoir intervals on Troll West.

Three main facies associations FA-3 to FA occur in the Oxfordian Argiles rouges de Kheneg Formation in northwestern Algeria. They correspond respectively to the deeper part of a mixed siliciclastic-carbonate shelf, upper shoreface and offshore transition-lower offshore. The trace fossil association of the Argiles rouges de Kheneg Formation contains fifteen ichnogenera and is moderately diverse for the Upper Jurassic. The formation contains diverse and abundant deep water or dominantly deep water trace fossils (i.e. Belorhaphe, Chondrites, Helminthopsis, Nereites, Megagrapton). They indicate that a part of the formation was deposited in offshore transition to lower offshore environments.

DOI:10.17014/ijog.6.2.185-208 Cretaceous sediments are among the important petroleum system elements for hydrocarbon exploration in Tanimbar area. However, little is known about their facies associations and depositional environments. Facies association analyses have been carried out in fourteen surface sections. Early Cretaceous Arumit Formation comprises three facies associations: subtidal, intertidal, and supratidal deposits. A progradational open-coast tidal flat depositional environment suggests the deposition of sediments of the Arumit Formation. The presence of tidal rhythmites, mud drapes, and fluid mud in those sediments are diagnostic features of a tide domination process in deposition of this unit. Early to Late Cretaceous Ungar Formation in the studied area consists of four facies associations: intertidal, marine offshore to lower shoreface, upper shoreface, and foreshore deposits. An open-coast wave dominated depositional environment is proposed for deposition of sediments of the Ungar Formation. Wave dominated environments in the coarsening upward interval is represented by hummocky cross stratification, cross-bedded sand and gravel, planar parallel stratification, and low-angle stratified beds.

Ancient barrier islands are poorly understood relative to other clastic depositional environments, despite being prominent features along modern coastlines and important for understanding transgressive shoreline deposits. A new dataset of ancient barrier island dimensions (n=83 examples) addresses this knowledge gap with a quantitative analysis of barrier island sand body dimensions including thickness (vertical), length (shore-parallel direction), and width (shore-perpendicular direction). This dataset of barrier island deposits was compared to planform measurements made for modern islands (n=274), to investigate possible scaling relationships and other aspects of modern to ancient linkages. These measurements are nuanced and challenging to perform, and first-pass comparisons show that modern barrier islands should not be used as direct analogs for ancient systems. Nevertheless, results emphasize key depositional and preservation processes, and the dimensional differences between deposits formed over geologic versus modern time scales. Using the methods outlined herein, barrier island deposits appear to be 2-5x longer (p50 modern = 10.7 km; p50 ancient = 20.0 km), and 6-15x wider (p50 modern = 1.2 km; p50 ancient = 7.3 km) than modern barrier islands. We interpret the results to indicate that ancient barrier islands are time-transgressive deposits recording vertical amalgamation, and barrier island growth by lateral accretion, and progradation. When comparing single barrier islands, thickness measurements do not vary systemically between modern and ancient examples, suggesting that local accommodation dictates barrier island thickness as a preservation control. Gross length, width, and thickness measurements are too coarse for robust paleomorphodynamic calculations, therefore more detailed sub-environment analysis (e.g., upper shoreface delineation), with improved facies models, is required before rigorous quantifications can be generated. However, these initial comparisons do show scaling trends between length and width which could be leveraged, with caution, in the interim. As sea levels continue to rise, understanding barrier island motion and preservation will be central to predicting coastal change. Keywords: paleomorphodynamics, barrier island, scaling relationships, accommodation, shallow marine, dimension prediction, modern analog, reservoir, transgressive

Shoreface deltaic depositional systems (UDS) form excellent stratigraphic traps. The UDS are developed during the adverse sea-level conditions, which have a vital impact on the quantitative prediction of stratigraphic reservoirs. The prediction of accurate thickness and distribution of porous reservoir along the UDS is always a challenging job for exploration geophysicist. Since these oil and gas plays are purely thin-bedded reservoirs. They require a specific tuning frequency to resolve and predict the accurate thickness of the hydrocarbon-bearing zone. The band-limited seismic attributes are not reliable tools for developing cost-effective stratigraphic plays. The Fourier transformation tool such as continuous wavelet transforms (CWT) and thickness modelling for UDS (TMUDS) are executed on the gas-bearing UDS, Pakistan. Beyond the conventional amplitudes, the 37-Hz tuning block demarcates the gas-bearing reservoirs. The amplitude attenuation at 48-Hz validates the presence of coarse-grained sediments within the upper shoreface intervals of deltaic system. The blending of seismic, 37-Hz, and sweetness magnitudes completely recognizes the dominant reservoir fluids, which were unable to detect using the traditional mapping. The sweetness profile predicts a 20 m thick reservoir facie. The band-limited TMUDS reveals some tuning effects of ambiguous lithology and fluids. However, the post-stack seismic data processing within the designed amplitude spectrum of 12–55 Hz have greatly enhanced the physical parameters of thickness and presence of hydrocarbons. The 36-Hz trace sub-bands have predicted a 48 m thick reservoir facie along the UDS. The 36-Hz ESB confirms the presence of hydrocarbon-bearing coarse-grained deltaic facies, which are accumulated along the intersection point of shelf-slope of UDS. The quantitative plots of predicted thickness and acoustic impedances [AI] [g/c.c.*m/s] at 36-Hz CWT shows a strong correlation coefficient of R2 > 0.90. These observations take a lead over the band-limited amplitude-based seismic attributes for quantification for UDS. Hence, only the post-stack seismic data processing and interpretation based on the CWT wavelet can enhance the vertical thickness of the reservoir and the lateral extent with the least error. This workflow has robust stratigraphic implications for explorations for stratigraphic fairway for Lower Goru and acts as an analogue for local to regional clastic depositional systems within Asia and world similar depositional settings.

Guadalupian (middle Permian) ichnoassemblages are described from the Mungadan Sandstone Formation (Kennedy Group), Merlinleigh sub-basin, Carnarvon Basin of Western Australia. In this formation, we recognize five facies (pebbly sandstone, intensely bioturbated sandstone, medium- to coarse-grained cross-stratified sandstone, fine-grained sandstone, and planar laminated siltstone), assigned to two facies associations, interpreted as the deposits of wave-dominated upper shoreface and lower shoreface settings. Ichnoassemblages, which contain 23 ichnospecies in 18 ichnogenera, are assigned to the Skolithos and Cruziana ichnofacies, as well as mixed types, and include representatives of cubichnia, repichnia, pascichnia, fodinichnia, domichnia, and agrichnia, indicating diverse trace-making behaviours. High burrow-density with monospecific occurrences of Skolithos indicate R-selected life strategies and burrow production over a short time period. The anomalous occurrence of Paleodictyon implies that the trace-making organisms of graphoglyptids could inhabit resource-rich shoreface environments as well as resource-limited deep sea niches. To better understand ichnological evolution across the Permian-Triassic (P-Tr) boundary, a database of Permian to Middle Triassic ichnoassemblages was also compiled for wave-dominated shoreface settings (WDSS) globally, and three ichno-ecological measures (ichnodiversity, ethological category, and ichnodisparity) were evaluated. Ichnodiversity shows a stepwise decline in ichnotaxa through the Permian, a pronounced increase in the Early Triassic, and a second phase of decline towards the Middle Triassic. Ethological data exhibit a different trend, with mean and median values dramatically dropping to a late Permian nadir, followed by a significant increase across the P-Tr boundary, culminating in an Early Triassic acme. The globally depauperate nature of late Permian ichnoassemblages may reflect sampling bias or decreased preservation potential resulting from abundant benthos and well-developed mixed layer in the seafloor. The presence of anomalously diverse Early Triassic ichnoassemblages may be due to the WDSS habitat providing a ‘habitable zone’ for trace-making organisms to survive when most marine environments were stressful in the aftermath of the P-Tr mass extinction. We emphasise that caution is needed in interpreting ichnodiversity variations across the P-Tr mass extinction event, as it may reflect shifting of trace-making behaviours of the same animals, or replacement of different animals with the same behaviours.

The up to 60 m thick Neurath Sand (Serravallian, late middle Miocene) is one of several marine sands in the Lower Rhine Basin which were deposited as a result of North Sea transgressive activity in Cenozoic times. The shallow-marine Neurath Sand is well exposed in the Garzweiler open-cast mine, which is located in the centre of the Lower Rhine Basin. Detailed examination of three sediment profiles extending from the underlying Frimmersdorf Seam via the Neurath Sand and through to the overlying Garzweiler Seam, integrating both sedimentological and palaeontological data, has enabled the depositional setting of the area to be reconstructed.Six subenvironments are recognised in the Neurath Sand, commencing with the upper shoreface (1) sediments characterised by glauconite-rich sands and an extensive biota (Ophiomorphaichnosp.). These are associated with the silt-rich sands of a transitional subenvironment (2), containingSkolithos linearis, Planolitesichnosp. andTeichichnusichnosp. These silt-rich sands grade up to the upper shoreface subenvironment (1), which is indicative of an initial regressive trend. The overlying intertidal deposits can be subdivided into a lower breaker zone (3), characterised by ridge-and-runnel systems, and the swash zone (4) where the surge and backwash of waves resulted in the deposition of high-energy laminites. The intertidal deposits were capped by aeolian backshore sediments (5). Extensive root traces present in this latter subenvironment reflect the development of the overlying peatland (i.e. Garzweiler Seam). Within the Garzweiler Seam, restricted sand lenses indicate a lagoonal or estuarine depositional environment (6). Regional correlation with adjacent wells establishes that shallow-marine conditions were widespread across the Lower Rhine Basin in middle Serravallian times. The shoreline profile, characterised by both tidal and wave activity and influenced by fluvial input from the adjacent Rhenish Massif, is indicative of the complexity of the coastal depositional setting within the Lower Rhine Basin.

This study presents the first detailed sedimentological and ichnological study of the Cambrian Mount Clark Formation from the Colville Hills region of the Northwest Territories, Canada. Based on analyses of four industry drill cores, eight lithofacies are identified that occur in a recurring facies association. This facies association records a progradational storm-influenced shoreface succession preserving offshore to upper shoreface sedimentary environments. Storm influence is indicated by the presence of hummocky cross-stratification (HCS) and of tempestite/fair-weather couplets consisting of low-angle cross-bedded sandstone with thin bioturbated interbeds. Marine flooding surfaces are expressed as pebbly transgressive lags that separate near-shore and overlying offshore sedimentary environments. Piperock is common, represents the most oil stained lithology, and is preserved within a wave-dominated shoreface succession. The sedimentological and ichnological character of this succession suggests that predictable shoreface stacking patterns and sandstone distributions characterize the Mount Clark Formation in the subsurface of the study region.

During the early Cambrian, the Danish island Bornholm was situated on the northern edge of the continent Baltica with palaeolatitudes of about 35°S. An early Cambrian (Terreneuvian) transgression inundated large areas of Baltica including Bornholm creating shallow marine and coastline environments. During this period, wave-formed shoreline sediments (the Vik Member, Hardeberga Formation) were deposited on Bornholm and are presently exposed at Stroby quarry. The sediments consist of fine- and medium-grained quartz-cemented arenites in association with a few silt-rich mudstones. The presence of well-preserved subaqueous dunes and wave ripples indicates deposition in a wave-dominated upper shoreface (littoral zone) environment, and the presence of interference ripples indicates that the littoral zone environment experienced water level fluctuations due to tides and/or changing meteorological conditions. Discoidal structures (medusoids) are present in the quarry, but due to the relative poor preservation of their fine-scale structures it is difficult to determine if the discoids represent true medusae imprints or inorganic structures. The preservation of the shallow-water bedforms as well as the possible medusae imprints is related to either the formation of thin mud layers, formed during a period of calm water when winds blew offshore for a longer period, or to the growth of bacterial mats. The orientation of the wave-formed bedforms indicates a local palaeoshoreline trending NE–SW and facing a large ocean to the north.