Abstract: Recent studies in the Middle Jurassic Bryne and Sandnes formations, primary reservoirs in several fields across the Norwegian and Danish North Sea, show the widespread occurrence of tidal-influenced and tide-dominated deposits. Aalenian–Bajocian Bryne cores reflect deposition by a shoal water, tidally influenced delta onto a low wave energy tidal platform (both supratidal and intertidal) that probably occupied the majority of the Søgne Basin, a narrow rift system connected to the Central and Danish graben and transgressed from an open-marine basin, possibly located to the south. At the Bathonian–Callovian boundary, a new phase of rifting and progressive salt movements led to the deposition of the upper Bryne and Sandnes formations within an 80–100 km long composite estuarine valley. Basin tilting to the south and continued transgression resulted in tidal deltas that offlap the northern margin of the basin. The basin was fully transgressed by the end of the Callovian. From the Late Bathonian onwards, differential tectonic movements along the broadly interconnected Middle Jurassic rift basins led to a change in the transgression direction from south to north, with an open-marine basin located in the Central and Viking graben.

Abstract Shelf-edge deltas are the main driver for the delivery of sediment to the deep water lowstand systems tracts. However, the mere presence of deltas at the shelf margin does not guarantee accumulation of deep-water sands. The two main reasons for this are: (1) deltas that develop at the shelf edge during relative sea-level fall generally need to be significantly incised by their own distributaries for sand delivery to be focused down to a basin-floor fan system, and (2) deltas that develop when sea level is rising (late lowstand) tend to be inefficient sand-delivery systems, and disperse sand mainly onto the slope as sheet-like turbidite lobes, with few or no basin-floor fans. Thus, given the presence of deltas at the shelf-edge, both the likely magnitude and direction of sea-level change at the shelf edge needs to be estimated, before significant time-equivalent, deep-water sand can be predicted on the basin floor. Shelf-edge deltas are generally thicker, significantly more unstable, and markedly more turbiditeprone than inner/or mid-shelf deltas. These major differences are due to longer run-out slopes (greater water depths), steeper mud-prone slopes, and greater accommodation at the shelf margin compared to deltas in more proximal shelf settings. There are four main types of shelf-edge deltas that have been documented from a database developed mainly from the Eocene shelf margin on Spitsbergen and the Miocene shelf margin of the Carpathian Foredeep: Type A deltas develop on the outer shelf/shelf-margin transition but without significant progradation beyond the shelf edge onto the slope. These deltas usually form during the falling stage of a fall-to-rise cycle on the shelf. Type B deltas develop at the shelf margin but are significantly cannibalized by fluvial-feeder erosion. Such deltas also form during falling stage, but base level falls below the shelf edge. The deltas are fairly sharp based on the outer shelf, are sand prone, and are deeply eroded by their own river distributaries. Because of the fluvial incision, only remnants of these deltas are preserved. However, their main significance and legacy is their time-equivalent, downslope suite of deep water, lowstand deposits including basin-floor fans. Type C deltas develop at the shelf edge, produce significant basinward growth of the shelf margin but rarely link down to basin-floor fans. They form during a late, rising stage of the fall-to-rise cycle, as they overlie earlier cannibalized deltas and older basin-floor fans of the same sequence. They are many tens of meters thick and consist of stacked, well-developed upward-coarsening and thickening units.. Type D deltas are progradational to aggradational delta complexes at the shelf margin, without underlying shelf-edge erosion, and only rare, linked basin-floor fans. Type A and C deltas simply amalgamate during a fall-to-rise cycle to become a single, thick (many tens of meters) deltaic wedge that is perched at the shelf margin and drapes far out onto the slope.

Sandy shelf-margin clinoforms in the Eocene strata of the Central Tertiary Basin of Spitsbergen are usually generated by river-dominated shelf deltas, or by wave-dominated shorelines, though these two regimes can also be strike-equivalent to each other. Clinoforms occur in series or sets that show both sub-horizontal and rising trajectories of shelf-edge accretion. Clinothems involved in the former style of margin growth, however, tend to be dominated by delta deposits. Shelf-edge deltas of such clinoforms are commonly severely eroded by their own distributary channels, and this is especially noticeable at (though not restricted to) shelf-edge locations. Fluvially incised shelf edges are commonly linked directly across the shelf break, to turbidite-filled channels, gullies and small canyons on the slope. Examples of this type of shelf-edge situation are present on Brogniartfjellet in Van Keulenfjorden, where the outer-shelf segment of the clinothem contains shelf-edge deltaic units that are 20-30m thick deposited during falling base level and lowstands. The deltas have been cut by deep erosive channels (up to 12 m) paved by shale rip-up conglomerates. The channel infill is dominated by up to 3 m-thick, flat and low-angle laminated, medium-grained sandstone bedsets deposited from upper-flow-regime conditions in riverine and shallow sand flats. Multiple phases of erosion can be demonstrated, separated by phases of minor re-establishment of delta-front facies. At peak regression of the delta system, still during falling relative sea level, the channels have reached the shelf break and allowed the river system to feed sediment directly into slope channels that were turbidity-current conduits to the basin floor. These are incised more than 25m deep on the upper slope, appear to have originated from fluvial input and retrogressive slumping on the slope, and link back up to the shelf-edge incisions. The infill of the slope conduits strongly suggests repeated phases of erosion/bypass that alternated with phases of low-efficiency, hyperpycnal-flow deposition. The apparent off-lapping architecture within the slope conduits strongly suggests oblique or downslope accretion of infill during continued relative fall (forced regressive and lowstand conditions) of sea level, and probably during basin-floor growth of the fan. In the latest stage of the lowstand, the shelf-edge deltas have re-established themselves onto the shelf, aggrading and prograding onto the underlying canyonized succession, thus forming a lowstand prograding wedge. Minor fluvial incision occurs, but overall the system is less sand prone. During the subsequent transgression of the shelf, when sea rose back up to and above the shelf edge, the slope is blanketed by mud, there is tidal re-working and infilling of the older shelf-edge channels and a transgressive barrier/lagoon or estuary system migrated landwards.

ABSTRACT The Permian Upper Rotliegend Group in the UKCS Quads 48-49 was deposited in a mixed aeolian–fluvial–playa– lacustrine environment which displays different orders of internal cyclicity. A low-frequency backstepping–forestepping depositional sequence, which encompasses the whole Rotliegend succession in the study area, was probably influenced by a long-term tectonic control. This depositional sequence can be subdivided into five cycle sets, 30–70 m thick, designated Unit U1 to Unit U5. These units are defined by the recognition of marked shifts in the evolution of depositional systems. The cycle sets are in turn subdivided into 16 elementary cycles (15–20 m thick), bounded by regionally widespread surfaces picked at the point of lower aridity. These high-frequency cycles show drying-upward and drying–wetting-upward trends. The Base Permian Unconformity shows a consistent topographic relief, and it represents a major sequence boundary. The lower part of the sedimentary succession, dominated by the deposits of semipermanent braided streams and catastrophic floods, was deposited in relatively confined sub-basins controlled by extensional WNW–ESE-trending faults. The fluvial system merged basinward into playa and lacustrine facies associations (U1). Vertically, the succession records a climatic change from more humid conditions (U1) to a first aridity peak (U2) marked by erg expansion and a change in fluvial style, with ephemeral streams between the erg and the inherited structural highs. The aridity peak was combined with a smoother palaeotopography. The middle to upper (U3–U5) part of the succession was deposited during a phase of tectonic quiescence in which the initial pronounced palaeotopography was almost completely leveled. Following a dramatic climatic shift toward more humid conditions, an erosional surface cut deeply into the underlying erg complex. This wetting phase was responsible for sudden deactivation of erg expansion between U2 and U3, abrupt reorganisation of depositional environments, and overall backstepping of facies belts (U3). As a consequence of the maximum Silverpit Lake expansion, the depositional setting was characterised by strong lateral uniformity in the study area. Relatively confined fluvial systems fed thin and isolated sandstone lobes interbedded with lacustrine mudstones, which alternated with anhydrite-rich mudstones. These latter deposits, testifying to dry maxima, were correlative toward the margin of the basin with aeolian sandstones, highlighting the contraction of the playa lake (U4). Following this prolonged stage, the sedimentary environment was characterised by deposition of gravity-flow-dominated delta-front lobes in the study area. This depositional change suggests active progradation under relatively humid conditions which characterised the uppermost interval of the Upper Rotliegend Group (U5). The proposed hierarchy of the sedimentary succession, located at the interaction between fluvio–aeolian and playa– lacustrine depositional environments, provides a tool for the understanding of their mutual relationships in the UK sector (Rotliegend feather edge) as well as in the Dutch and German regions.

Abstract Storvola is a Spitsbergen mountainside outcrop (1 km x 10 km [0.6 mi x 6 mi]) that exposes the coastal plain, shelf, slope, and basin-floor reaches of a series of lower Eocene clinoforms (Figure 2B, C). The clinoforms have decompacted amplitudes of some 300–350 m (984–1148 ft) reflecting basin water depths of this magnitude at times of relative sea level lowstand (from shelf edge to basin floor). Type 1 shelf margins typically have relatively deep incision of river distributary channels on their shelf-edge reaches, turbidite channels, and large-scale disruption (growth faults, rotated blocks, and large slump complexes) on their mud-prone slopes, and sand-rich fans on their proximal basin-floor reaches. In contrast, Type 11 shelf margins (see Plink-Bjorklund and Steel, chapter 70, this volume) have their sediment budget partitioned differently in the clinoform. They have limited incision at the shelf edge, and strike-extensive, sand-rich upper and middle slopes, but have no basin-floor fans. The contrasts between Type I and Type II margins are summarized in Figure 2A. Clinoform 14 on Storvola, illustrated here as our Type 1 shelf-margin example (Figure 2B), consists of a regressive delta phase on the shelf platform, a falling-stage and lowstand phase of sandy sediment gravity flows in deep-water channels of the shelf margin (below the shelf edge) and deep-water basin floor, and a transgressive estuarine phase back on the shelf platform. These three phases can be further subdivided into seven segments:

Abstract The Ainsa turbidite system is part of the slope fill of the Ainsa basin. It was deposited in foredeep and wedge-top depozones. The base of the system is an angular unconformity; the top is a gradual facies change to a mudstone-dominated unit. Maximum thickness is 305 m (1000 ft) and preserved width and length are 8 km (4.9 mi) and 9 km (5.6 mi), respectively. Mean paleoflow is to the northwest, parallel to the main axis of the basin. The system consists of three cycles of channel complex development and abandonment. In the basal part of these cycles, there are one or two channel complexes that are nearly straight. The dimensions are greater than 1.5 km (0.9 mi wide), greater than 9 km (5.6 mi long), and up to 100 m (328 ft) thick. channel complexes are bounded laterally and above by thin beds that represent overbank and frontal-splay deposits, or by slump deposits with a dominant mudstone composition. Synchronous thrusting and folding caused the angular character of the basal unconformity, the marked thinning of the system towards the basin margins, the progressively rotated cycle boundaries, the frequent multilateral architecture of channel-complexes, and in some cases, channel-complex divergences around growing anticlines. The outcrop corresponds to a partial section of one of the two channel complexes in the lowermost cycle. Mean paleoflow is to the west-northwest (290°) and the outcrop trends 160°–340°. The base of the channel complex is not exposed. It is interpreted to be a few meters (>10 ft) below the stratigraphically lowest beds in the outcrop.

Abstract The Arro turbidites (Eocene San Vicente Formation) were deposited as part of the infill of the Ainsa basin during the foredeep stage of basin development. Their maximum thickness is 180 m (590 ft) with a preserved length of 16 km (10 mi) and width of 4 km (2.5 mi). Net-to-gross is approximately 40%. The Arro turbidites have been interpreted as a canyon-mouth sheet system that was deposited in a base-of-slope setting. The system is elongate with deposition occurring in the axis of the foredeep basin. Flanking the deposits was an active margin slope. The Arro turbidites have been correlated updip to a canyon fill that is incised in shelf deposits. The Los Molinos road outcrop is a partial section of the Arro turbidites. This section is 180 m (590 ft) long, transverse to the northwest-directed paleoflow. It is located approximately 4.2 km (2.6 mi) from the canyon-fill locality. Here, the Arro turbidites rest on top of a mudstone succession and reach their maximum thickness (180 m [590 ft]). Four classes of architectural elements, ranging in thickness from 1–20 m (3–66 ft), are present in the outcrop. These include 1) mudstone-rich, thin-bed elements (TM) with net-to-gross up to 30%, 2) sandstone-rich, thin-bed elements (TS), with variable net- to-gross (30–70%) and common erosive bedding, 3) thick-bed elements (C), mostly channel forms, with net-to-gross up to 90%, and 4) slump-deformed, mudstone-dominated units (SM). The lower interval of the studied succession (lower two-thirds of exposure) contains abundant slumps and thin beds. channel forms are rare, and where present,

Abstract: The Campanian Hatfield Member of the Haystack Mountains Formation is composed of two well-exposed marine sandstone tongues that extend up to 35 km basinward from their earliest shoreline position into the Western Interior Seaway. Each tongue (HI and H2) is comprised of two parts that have characteristic architecture, external geometry and facies assemblages. Together, the tongues form a stratigraphic sequence that is formed of four systems tracts and bounded by erosional unconformities. The sequence is interpreted to have been generated over an interval of less than 1 Ma during a fall-to-rise cycle of relative sea level. The earliest and latest systems tracts of the sequence, interpreted as lowstand prograding deltaic wedge and forced regressive shoreface respectively, are distinguished on the basis of their position with respect to the sequence-bounding unconformities, reconstructed shoreline trajectories, and by their component facies that indicate the dominant depositional regime. The mapped basinward shift of the Hatfield 1 lowstand prograding wedge from the previous shoreline deposits and erosional relief on the sequence boundary, indicates a relative sea-level fall prior to its deposition. The lowstand prograding wedge consists of parasequences that are dominated by tidally influenced cross-stratified sandstones and step for more than 30 km basinward, and are readily distinguished from the underlying highstand shoreface facies. Distal aggradational stacking of the lowstand produced a slightly rising shoreline trajectory that in combination with proximal onlap against the underlying erosional unconformity indicates accumulation under conditions of rising relative sea-level with abundant sediment supply. The domination of tidally influenced facies and an estimated relief of at least 20 m in proximal reaches of the underlying sequence boundary suggests that the lowstand wedge was a tidally dominated deltaic system localized and fed through an incised valley. This systems tract resembles other cross-stratified Mancos-type sandstone bodies of the Western Interior Seaway which have been under debate. However, unlike most of these, the Hatfield 1 has great outcrop extent and the updip relationship of the lowstand wedge with the older shoreline deposits can be traced. The overlying retrogradational Hatfield 1 transgressive systems tract has comparable facies to the lowstand wedge and also shows proximal onlap of the sequence boundary, suggesting that it developed within a tidally influenced estuary. As such, the lowstand and transgressive systems tracts form a distinctive cross-bedded tidally influenced lithosome that is readily distinguished from the wave-dominated lithosomes of the preceding Hatfield 1 highstand systems tract and the overlying Hatfield 2 highstand and forced regressive systems tracts. The Hatfield 2 forced regressive systems tract is a wave-dominated shoreface that like the preceding Hatfield 2 highstand shoreface is strongly progradational. However, in contrast to the highstand shoreface from which it builds, the forced regressive shoreface is relatively thin, lacks shaley offshore transitional facies at its base, and displays a downstepping trajectory relative to the underlying MFS. The basal surface of the forced regressive shoreline also has an enrichment of coarse glauconitic grains derived from erosion of the underlying condensed section whereas the upper bounding surface of the systems tract is an erosional unconformity, documenting the maximum fall in relative sea level. There is a clear sedimentological distinction of the lowstand and forced regressive systems tracts because whereas the former has a tidally influenced facies association, forced regressive facies tend to be wave-dominated. Such facies partitioning and style contrast are thought to reflect the less-confined nature of the highstand and forced regressive shorelines in comparison to the incised or embayed nature of the lowstand and transgressive shorelines.