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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 middle Devonian, shoreface quartz arenites (present-day burial depths 2833-2786 m) are important oil and gas reservoirs in the Ghadamis Basin, western Libya. This integrated petrographic and geochemical study aims to unravel the impact of depositional facies on distribution of diagenetic alterations and, consequently, related reservoir quality and heterogeneity of the sandstones. Eogenetic alterations include the formation of kaolinite, pseudomatrix, and pyrite. The mesogenetic alterations include cementation by quartz overgrowths, Fe-dolomite/ankerite, and illite, transformation of kaolinite to dickite, illitization of smectite, intergranular quartz dissolution, and stylolitization, and albitization of feldspar. The higher energy of deposition of the coarser-grained upper shoreface sandstones combined with less extensive chemical compaction and smaller amounts of quartz overgrowths account for their better primary reservoir quality compared to the finer-grained, middle-lower shoreface sandstones. The formation of kaolin in the upper and middle shoreface sandstones is attributed to a greater flux of meteoric water. More abundant quartz overgrowths in the middle and lower shoreface is attributed to a greater extent of stylolitization, which was promoted by more abundant illitic clays. This study demonstrated that linking the distribution of diagenetic alterations to depositional facies of shoreface sandstones leads to a better understanding of the impact of these alterations on the spatial and temporal variation in quality and heterogeneity of the reservoirs.

Tidal processes can have a significant impact on the sedimentological and ichnological character of wave-dominated shoreface deposits. As the influence of tides increases, the resulting shoreface successions begin to depart markedly from those postulated by the conventional, wave-dominated shoreface model, which was built upon essentially non-tidal shoreline settings. In shoreface settings subject to stronger tidal flux, tides can be manifest either directly or indirectly. Direct tidal effects refer to those characteristics imparted by tidal energy (e.g., tidal currents) per se , and are best expressed in offshore and lower shoreface positions. Key evidence of direct tidal control includes uniform sediment calibres from the upper shoreface to the offshore, and little or no mud preserved in the lower shoreface. Additionally, sands in the lower shoreface and offshore tend to be intensely bioturbated. Where primary stratification is preserved, it largely comprises current-generated structures. Such shoreface deposits are referred to herein as “tide-influenced shorefaces”, and are expected in settings with low storm-wave input coupled with strong tidal currents (e.g., straits). Indirect tidal influences are manifest by the lateral translation of wave zones across the shoreface profile owing to changes in water depth during the tidal cycle. This is best developed in macrotidal to megatidal settings. Indirect tidal influences are more pronounced in the upper and lower shoreface, and are recorded through the interbedding of sedimentary structures produced by shoaling waves, breakers and surf, swash–backwash, and surface runoff. The boundaries between shoreface subenvironments are correspondingly poorly defined. The foreshore in settings of elevated tidal range is also generally much thicker (typically 4 to 5 m). Bioturbation tends to be patchy in distribution across the shoreface, and dominated by vertical structures. Such systems are defined as “tidally modulated shorefaces”. Using well-established sedimentological and ichnological criteria for recognizing wave-dominated (non-tidal) shorefaces — wherein sediment deposition is nearly wholly controlled by fair-weather wave and storm-wave processes — a conceptual model is developed for discriminating fair-weather (non-tidal) shorefaces, storm-influenced (non-tidal) shorefaces, and tidally influenced shorefaces. Five shoreface archetypes are defined: storm-affected, storm-influenced, storm-dominated, tide-influenced, and tidally modulated.

The Upper Cretaceous John Henry Member of the Straight Cliffs Formation preserves regressive shoreface and channel facies, and transgressive lagoonal tidal inlet facies that suggest distinct modal sandstone compositions. Detrital modes from six sandstone facies (upper shoreface, lower shoreface, deflected mouth bars, fluvial channels, tidal inlets and washover fans), and their spatial and temporal variations, provide additional data regarding the depositional environments and setting of the John Henry Member. Three statistical methods were utilized: univariate standard deviation and confidence interval and multivariate logratio transformations to assess the compositional difference between facies using estimation of means. Both univariate statistical methods have some inherent problems. Standard deviation does not account for sample size, while the confidence interval method incorporates a t-test to account for only some of the uncertainty of small sample size. The results of the univariate methods differ slightly and both indicate statistically distinct sandstone compositions based on facies. Multivariate statistics are much more robust and suggest similar trends, yet display different compositional means and have inconclusive confidence fields as they incorporate all of the uncertainty associated with small sampling sizes. In general, sandstone compositions become more quartz-rich and compositionally mature as sediment is transported from proximal fluvial environments to distal upper shoreface environments. This trend reflects the degree of preferential reworking or winnowing of unstable grains prior to lithification. More complicated relationships are observed as facies distributions shift through space and time. Sandstone compositions support a deflected wave-dominated deltaic interpretation for the John Henry Member in this area. Sandstone compositions become more lithic-rich from north to south, corresponding to the facies distribution of upper shoreface and deflected mouth bars, respectively. Mouth bars occur at the intersection of the fluvial channel and the coastline where sand is deflected via longshore drift to the southern portion of the field area. Upper shoreface facies located further away from mouth bar facies are heavily reworked by wave processes and contain more mature quartz-rich modal compositions. Additionally, high feldspathic and lithic concentrations in tidal inlet facies suggest that this facies was sourced closer to mouth bars rather than updrift upper shoreface sediments. A shift in sandstone composition occurs at the end of the second transgressive–regressive cycle of the John Henry Member throughout the Rogers Canyon area. This compositional change is concurrent with a relatively large basinward shift in facies, which suggests that it reflects the transition from regressive to transgressive facies associated with the relative sea level fall rather than a change in the main sediment source area.

A thin (3–25 cm), persistent conglomerate-sandstone unit occurs at the base of the transgressive systems tract of an Upper Pennsylvanian cyclothem below a transgressive limestone in outcrop and subsurface in SE Kansas and NE Oklahoma. It has an erosional base and a sharp top, and is composed of calcitic clasts, some shell fragments and quartz sand, and rare coal fragments. Clasts are rounded, equant-to-elongate, coarse sand-to-pebble sized, and moderately to well sorted. They are micritic to microsparitic or radial fibrous calcite grains and pisoids. Micritic and microsparitic clasts are heterogeneous and contain rounded to elongate moulds and radiating or concentric, spar or micrite-filled cracks. Pisoids have micrite cores and superficial calcite or clay rims. The clasts have similar texture and composition to the calcitic nodules and rhizoconcretions in underlying paleosols, and thus were probably derived from these soil nodules. Upper shoreface erosion during shoreline transgression excavated the underlying paleosols and eroded coeval transgressive deposits landwards of the shoreline. The eroded sediments were then reworked and transported to the lower shoreface and inner shelf by storm return flows to be deposited as a soil-nodule conglomerate-sandstone unit. Its base is an amalgamated surface of wave ravinement and initial transgression as well as the lower sequence boundary. The widespread conglomerate-sandstone unit suggests extensive transgressive wave ravinement on an epicontinental shelf. The transgressive record composed of upward-deepening, dominantly fine-grained lithofacies defines a new type (T-C4) of transgressive record, which is composed of mixed carbonate and siliciclastic lithofacies with a simple transgressive lag on a low-relief shelf.

The Merced Formation comprises a 2-km-thick shallow marine and non-marine succession that was deposited in a small transtensional basin along the San Andreas Fault during the late Pliocene to middle Pleistocene. The sediments dip between 10° and 80° to the northeast, and are locally disrupted by small faults. During tilting, the beds have been rotated into subparallelism with the San Andreas Fault zone, splays of which bound the outcrop belt of Merced sediments to both the southwest and northeast. The Merced Formation contains more than 20 transgressive–regressive sedimentary rhythms (cyclothems, or sequences) that are generally between 40 and 120 m thick, and which were deposited mostly during interglacial time, under the influence of rising, highstand and early falling sea levels. Sequences Merced-2 [units M1–N of Soc. Econ. Paleontol. Mineral., Field Guidebook 3 (1984) 1] and Merced-3 (units O–P), though in fault contact, comprise typical Plio-Pleistocene shallow water cyclothems. The Merced-2 Sequence is 22+ m thick, and comprises a sandy and shelly transgressive systems tract, including a basal Type A shellbed, an in situ Type B mid-cycle shellbed, and a highstand systems tract of massive siltstone. The Merced-3 Sequence is 47 m thick, and comprises a basal compound shellbed, a thin highstand systems tract siltstone, and a sand-rich regressive systems tract. The RST comprises distal shoreface sands with an abundant in situ molluscan fauna, and upper shoreface and back-beach trough cross-bedded sands and pebbly sands. The top of the Merced-3 cycle comprises a beach sand capped by a palaeosol and lignite (the “Beetle Bed”), which together mark the subaerial exposure of the site during the ensuing glacial sea-level lowstand. Analysis of 10Be across the Merced-3 Sequence shows major peaks, indicative of sedimentation starvation, in the basal transgressive systems tract shellbed and in the capping lignite of the Beetle Bed. Smaller 10Be peaks are associated with a shellbed that is inferred to represent winnowing at the foot of the shoreface, and with a minor exposure surface that delimits a small paracycle in the top of the sequence. Otherwise, 10Be abundances decline regularly across the Merced-3 Sequence, consistent with an increasing sedimentation rate as shoreface progradation, and regression, progressed. The character of cycles Merced-2 and Merced-3 respectively resembles the Seafield and Rangitikei sequence motifs described from similar Plio-Pleistocene sediments in New Zealand. The cycles are of mid-Pleistocene age, and were probably deposited during interglacial oxygen isotope stages 21 and 19, respectively.

Gravelly shoreline deposits of the latest Pleistocene highstand of Lake Lahontan occur in pristine depositional morphology, and are exposed in gravel pits along Churchill Butte in west-central Nevada. Four environments differentiated at this site are alluvial fan/colluvium, lakeshore barrier spit, lake lower-shoreface spit platform, and lake bottom. Lakeshore deposits abut, along erosional wave headcuts, either unsorted muddy to bouldery colluvium fringing Churchill Butte bedrock, or matrix-supported, cobbly and pebbly debris-flow deposits of the Silver Springs fan. The lakeshore barrier spit is dominated by granule pebble gravel concentrated by wave erosion of the colluvial and alluvial-fan facies. The lakeward side of the barrier consists of beachface deposits of well-sorted granules or pebbles in broad, planar beds 1–10 cm thick and sloping 10–15°. They interfinger downslope with thicker (10–25 cm) and less steep (5–10°) lakeward-dipping beds of fine to medium pebble gravel of the lake upper shoreface. Interstratified with the latter are 10–40-cm-thick sets of high-angle cross-beds that dip southward, alongshore. Higher-angle (15–20°), landward-dipping foresets of similar texture but poorer sorting comprise the proximal backshore on the landward side of the barrier. They were deposited during storm surges that overtopped the barrier berm. Gastropod-rich sand and mud, also deposited by storm-induced washover, are found landward of the gravel foresets in a 15-m-wide backshore pond. Algal stromatolites, ostracodes, and diatoms accumulated in this pond between storm events. The lake lower shoreface, extending from water depths of 2 to 8 m, consists of a southward-prograding spit platform built by longshore drift. The key component of this platform is large-scale sandy pebble gravel in 16° southward-dipping `Gilbert' foresets that grade at a water depth of about 6–7 m to 4°-dipping sandy toesets. A shift from bioturbated lower-shoreface sand and silt, to flat and laminated lake-bottom silt and mud, occurs between water depths of 10–40 m and over a shore-normal distance of ≥250 m. This lake-bottom mud facies, unlike the others, is areally expansive.

Several third-order slope-shelf-nearshore depositional sequences are found in the Middle to Late Miocene Aoki and Ogawa Formations in the southern part of the Northern Fossa Magna region, central Japan. Each depositional sequence consists of a transgressive systems tract, varying in thickness from several tens of centimetres to about 10 m, a falling stage systems tract several tens of metres in thickness and a highstand systems tract, 20–80 m thick. The highstand systems tract and falling stage systems tract are bounded by the regressive surface of marine erosion. Each depositional sequence mainly consists of coarse-grained sediments. The materials of the transgressive conglomerate beds were derived from the gravelly foreshore and upper shoreface by transgressive shoreface erosion. The thin and conglomeratic transgressive systems tract indicates that these slope-shelf-nearshore sequences were deposited on the steep slope area under a rapid transgression. Therefore, these sequences were formed in response to excess sediment supply and a rapid rise in relative sea-level at an active margin of the backarc side of the arc-trench system.

Measurements from the Texas coastal margin, a microtidal, fetch-limited, wind-dominated shallow sea, reveal a strong correlation in timing and direction of surf zone and shelf flow during both fairweather and storm events. Coherence of current motion is statistically significant at many frequencies (cycle lengths) and is highest during storm events. The lack of a significant lag between surf zone and shelf flow indicates that both respond rapidly to changes in the magnitude and direction of the wind field. The alongshelf component of the wind stress is a major force in generating currents both on the shelf and in the surf zone, as exhibited by comparison of numerical predictions and observed velocities. During the 140-day study period, current flow was mainly directed alongshelf to the northeast and southwest, driven by southerly “fairweather” and northerly “storm” winds, respectively. However, the threshold for generation and migration of megaripple bedforms in upper shoreface bar-troughs was exceeded only during storm events when surf zone flow was oriented to the southwest, along the coast. This observation, coupled with the knowledge that storm-generated bedforms have the highest preservation potential, imply that multi-event traction bedding in upper shoreface bar-troughs of analogous ancient environments will be dominated by unimodal alongshore current orientations. Large-scale bedforms which respond to this time-averaged flow on the shelf are expected to display a similar unimodal alongshelf orientation with a low-angle deviation toward the offshore direction. Careful study of paleo-current measurements in a well-documented ancient shelf to shoreline sequence in the Cretaceous of New Mexico reflects this similarity in transport kinematics.

Late Palaeozoic Ecca sandstones near Bothaville, South Africa, are divided into three sedimentary facies. These facies are attributed to storm-influenced sedimentation in the lower shoreface, upper shoreface and foreshore of a non-tidal or microtidal beach, and record the dominance of wave surge in the lower shoreface, rip currents in the upper shoreface and swash action in the foreshore. The relatively common occurrence of inferred storm deposits in these and other ancient beach and shallow shelf sequences is probably due to their high preservation potential, especially along wave dominated non-tidal or microtidal coastlines where they are unmodified by tidal processes.