bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regional to Subregional Facies Architecture of River-Dominated Deltas in The Alberta Subsurface, Upper Cretaceous Dunvegan Formation
Authors: Bhattacharya Janok P. 
Published: November 2010

Abstract
The Dunvegan Formation (mid-Cenomanian) comprises a thick clastic wedge deposited in the West Alberta foreland basin. This wedge consists of a complex series of interbedded shales, siltstones, and sandstones and has been subdivided into seven allomembers (A-G), each separated by widespread flooding surfaces.
Allomember E consists of four offlapping, shingled, heterolithic sedimentary units that progressively built seaward to the southeast. Isolith maps of the sandstones within these shingles reveal deltaic morphologies consisting of well-developed sandy depositional lobes fed by sandy distributary channels separated by mudstone-dominated interchannel and interlobe areas. The plan-view morphologies and facies successions in the lobes are typical of prograding river-dominated delta fronts.
Superposition of sandbodies within each shingle reveals the autocyclic fashion in which the sedimentary basin was filled. The arcai pattern and scale of overlapping depositional delta lobes are similar to those of the Mississippi delta during the last 5 ka.
Architectural Patterns in Large-Scale Gilbert-Type Delta Complexes, Pleistocene, Gulf of Corinth, Greece
Authors: Ori Gian gabriele , Roveri Marco , Nichols Gary 
Published: November 2010

Abstract
Large-scale Gilbert-type delta deposits occur on the southern side of the Gulf of Corinth in Greece. They accumulated adjacent to the very steep margins of listric-fault blocks. The deltaic complexes consist of very thick (up to 700 m) foreset packages that pass into bottomset strata, which, in turn. pass into thin-bedded turbidites. Topset deposits are well preserved and are the keys to interpreting the fan-delta bodies in architectural terms. The geometric pattern is discussed in terms of accommodation, that is the vertical space made available for the sedimentation. Where there is no accommodation, the topset environment is bypassed and, geometrically, toplap boundaries occur. With increasing accommodation, fluvial topset strata are formed: they pass downdip into the foreset beds. At higher accommodation values, transgressive deposits occur. If accommodation is too high, the transgressive sediments are drowned and foreset beds form on top.
Sedimentology of a Sequence Boundary Within The Nonmarine Torrivio Member, Gallup Sandstone (Cretaceous), San Juan Basin, New Mexico
Authors: Miall Andrew D. 
Published: November 2010

Abstract
The Gallup Sandstone of northwest New Mexico consists of a series of sandstone tongues, deposited in strandplain environments, interbedded with fine-grained marine sediments of the Mancos Shale. The uppermost tongue includes shales and thin sandstones of the "nonmarine Gallup" and a prominent sandstone unit, the Torrivio Member. The latter has been interpreted as fluvial in origin. Earlier work by other researchers interpreted the Torrivio as the basal member of a transgressive sequence, which includes in its upper part open-marine shelf deposits of the upper Mancos Shale.
The nonmarine Gallup contains some evidence of marine influence and is interpreted here as a back-barrier tidal-flat or lagoonal deposit The overlying Torrivio Member is fluvial in its lower part, but some sections along the west and south flank of San Juan Basin contain tidal sand waves in the upper part of the member. A prominent bounding surface separates fluvial from tidally influenced beds in some localities, and it is suggested here that this is the position of the main sequence boundary, marking the time of maximum regression. The succession up to this bounding surface is that of a regressive, strandplain to fluvial parasequence. Above the surface, tidal deposits, probably representing estuarine sand shoals, form the base of a transgressive sequence.
Maximum regression may record the time of lowest relative sea level. However, there is no independant evidence of sea-level change. Current models that purport to explain changes in fluvial accomodation space with reference to changes in base level are flawed, and an alternative model of regional tectonism and resulting increases in sediment supply cannot be ruled out as a mechanism for the generation of fluvial tongues in foreland basins, such as the Torrivio Member.
Evolution of Middle Eocene Tide-Dominated Deltaic Sandstones, Lagunillas Field, Maracaibo Basin, Western Venezuela
Authors: Maguregui Jesus , Tyler Noel 
Published: November 2010

Abstract
Interpretations of net-sand/percent-sand maps, well-log cross sections, vertical log-pattem trends, core descriptions, and log facies suggest that several aggradational tide-dominated deltaic cycles were deposited in Lagunillas field. Western Venezuela, during a widespread transgressive event at the end of the Middle Eocene. Reservoir lithofacies present are estuarine distributary-channel sandstones, tidal sand-ridge sandstones, prodelta/shelf assemblages, and tidal-channel facies. Geometries of the sandstone bodies are highly dip elongate and strike lenticular. These shoestring sands maintain their widths in a landward direction (west) and splay outward at their seaward limit (east), where loci of sand deposition occurred. Eastward, the sequence thickens concomitant with a decrease in sand-to-shale ratio. Individual correlatable depositional units are interpreted to be discrete delta lobes established during progradation of estuarine distributary systems. These single delta lobes shifted laterally along strike during infilling of deltaic depositional axes. Laterally persistent low-resistivity shale markers stratigraphically bound several delta lobes, which together constitute one of five deltaic cycles present in the upper reservoirs of the field.
Architecture of Modern Subtidal Dunes (Sand Waves), Bay of Bourgneuf, France
Authors: Berné Serge , Durand Jacques , Weber Olivier 
Published: November 2010

Abstract
Improvements of geophysical acquisition and processing techniques and coring data give a new insight into the architecture of large subaquatic dunes. A field of dunes, with amplitudes ranging from 0.7 to 9.4 m. has been studied in the Bay of Bourgneuf. near the Loire inlet, France. Results show that the bedforms have steep lee sides and distinct asymmetry, and that the internal structure consists of steeply-dipping cross-strata truncated by several orders of bounding surfaces. The true dip angle of the laminae, measured on a core collected from a 3.6-m-high dune, suggests the existence of sandflow or sandfall processes, similar to those previously described in eolian dunes or small intertidal bedforms. The combined effect of waves and tidal currents is proposed to explain the strong asymmetry of the structures and the origin of bounding surfaces. Even if these dunes can be considered as tidal bedforms, seismic and core data suggest that the internal structure is probably the result of episodic, rather than cyclic, processes. If compared to the sand waves described by Visser from sheltered environments, this type of sandbody should be difficult to interpret in the stratigraphic record, because it does not display any "tidal criteria" (tidal bundles, mud couplets).
Facies Characterization and Architecture of a Muddy Shelf-Sandstone Complex
Authors: Cole Rex D. , Young Robert G. 
Published: November 2010

Abstract
The Mancos B interval of the Upper Cretaceous Mancos Shale is represented by up to 372 m of thinly interstratified clays tone, siltstone, and very fine- to fine-grained sandstone deposited offshore, below storm-wave base, in the Western Interior Seaway. The Mancos B is best developed along Douglas Creek Arch in western Colorado and eastern Utah, where it is a major producer of natural gas and a minor producer of oil.
Combined stratigraphic and sedimentologic data suggest that the Mancos B is a regressive prodelta-plume complex genetically related to deltaic systems active along the western shoreline of the seaway. In outcrop and subsurface cores, the Mancos B is characterized by lenticular, cyclic, upward-coarsening parasequences, ranging in thickness from 2 to 32 m, and composed of five main lithofacies: silty claystone, sandstone-claystone, sandy siltstone, bioturbated muddy sandstone, and sandy dolomite (as beds and concretions). Sedimentary structures include horizontal lamination, wavy lamination, lenticular bedding, flaser bedding, ripple lamination, and horizontal lamination. Paleocurrent measurements indicate an average sediment-transport direction to the southeast (111°). Trace fossils are characteristic of the Cruziana ichnofacies. Lateral lithofacies variations in Mancos B parasequences are characterized by transitions from bioturbated muddy sandstone lithofacies into sandstone-claystone lithofacies then into sandy siltstone or silty claystone lithofacies. Horizons of sandy dolomite lithofacies cap most parasequences and represent periods of low sedimentation.
Isolated Shallow Marine Sand Bodies
Authors: Snedden John W. , Bergman Katherine M. 
Published: November 2010

Abstract
Isolated shallow marine sand bodies detached from coeval coastal deposits and encased in marine mudstone have been a focus of research and exploration in sedimentary geology for over 30 years. Yet, their origin and occurrence continues to spark debate and motivate explorationists interested in accessing the hydrocarbons within these reservoirs. Interpretations of these complex and enigmatic sand bodies have evolved from genetic models based on physical and biological sedimentary structures to regional sequence stratigraphic models invoking allocyclic processes. This evolution of interpretation parallels the stepwise progression of sedimentary geology as a whole. The Shannon Sandstone of Wyoming is a well-documented example of this type of sand body that was originally interpreted as a shelf sand ridge on the basis of sedimentary structures and external geometry. Addition of local and regional stratigraphic studies have generated new ideas involving incised shoreface and estuarine valley-fill models. Determination of the correct model is critical, as the various interpretations imply significant differences in exploration approach and production characteristics.
The Shannon Sandstone
Authors: Tillman Roderick W. 
Published: November 2010

Abstract
The Shannon sandstones in the Powder River Basin of Wyoming have been interpreted by Tillman and Martinsen and others as having been deposited as sand-ridge complexes during transgression on a wide shelf in the Western Interior Seaway, which stretched from Alaska to Mexico in early Campanian time. In recent papers by other workers, the Shannon is interpreted to be a series of incised lowstand shoreface deposits or estuarine valley-fill deposits. The sand-ridge complexes are considered by different workers to have been deposited in a variety of sequence stratigraphic settings ranging from regression to sea level still-stand to transgression. The shelf sand-ridge model infers offshore deposition, possibly as far as 110-160 km from shore at middle shelf depths by south to south-southwest-flowing, shore-oblique currents intensified frequently by storms. A probable source of sediments for the ridges probably does not include shoreline sandstones to the west, but instead the Eagle Sandstone deltaic deposits of southern Montana which he 320 km to the north-northwest.
A model inferring that Hartzog Draw Field, a major Shannon sandstone oil producer, is a remnant of several sequence boundary incisions was recently developed by the current operators of the field. They recognize a sequence boundary at the base of the Shannon and two sequence boundaries within the Shannon. They infer that deposition of the Shannon is primarily by tidal processes. The incisions at the sequence boundaries are projected to cover tens of km laterally and if these are truly incisions they are believed by this author to have formed large open bays. To accommodate the presence of marine fossils that occur below, above, and between the thick fine- to coarse-grained Shannon Sandstone accumulations, where they occur on the Salt Creek anticline, several abrupt changes in sea-level would be required prior to, during, and following Shannon deposition.
A third model has been developed by Canadian authors who have used shoreface models developed for the Cretaceous in Alberta, Canada to explain the Shannon. Their model infers that the Shannon sandstones are a series of lowstand incised shorefaces.
This paper gives a historical perspective of interpretations of the Shannon during the last 25 years. The pros and cons of the various models are considered, and some of the problems with each model are discussed.
Shannon Sandstone of the Powder River Basin
Authors: Swift Donald J.P. , Parsons Brian S. 
Published: November 2010

Abstract
The Shannon Sandstone, consisting of cross-stratified, heterolithic sandstone and thin-bedded sandstone-shale alternations, is a sedimentary complex of ambiguous origin. It lies seemingly "encased in marine shale," far from its time-equivalent shoreline. It has been interpreted as a shelf sand ridge complex, as a detached lowstand wedge, and as a low-stand, deltaic valley fill. The Shannon Sandstone has experienced one of the higher rates of "paradigm shift" seen within the field of stratigraphy, as successive generations have tested it for successively popular depositional models.
Interpretation of the Shannon is best undertaken in the context of a three-fold family of Cretaceous marine sandstones. Class I Sandstones cap the progradational tongues of the Cretaceous cliff-forming sandstones. They are cross-stratified with shore-normal paleocurrent orientations, high in angular deviation, have clear tidal signatures, and are of transgressive, estuarine, valley-fill origin. Class II Sandstones exhibit high-angle to hummocky cross-stratification, are amalgamated to discretely bedded, and in the latter case exhibit shore-normal, sole markings with low angular deviations. Class III Sandstones exhibit high-angle cross-stratification, low angular deviation, along-shore (southerly) paleocurrent orientations, and are enriched in intrabasinal components (phosphatic, sideritic, and glauconitic nodules). They are of transgressive, open-marine origin, and in at least some cases were deposited as sand ridges. While the paleontological evidence appears to be contradictory, the highly glauconitic phases of the Shannon provide an insurmountable problem for the lowstand shoreface, and lowstand deltaic models. Both the high glauconite content and the along-shore paleocurrent pattern point to a shelfal origin for the Class III Sandstones as a group, and for the Shannon in particular.
A generic depositional model for the Class III Shannon Sandstone can be salvaged from elements common to the diverse explanations that have been offered, and by abandoning contradictory elements. In this synthesis, the Shannon Sandstone is considered to exhibit lithologies, textures, and structures indicative of transgressive deposition in a shallow open marine setting; both estuarine and outer shelf settings are rejected. The pattern of distribution is an inherited one; it is the consequence of in situ reworking of sediment delivered to the site of deposition by other means. However, the result is not a simple, band-like "stranded lowstand shoreline." In the subsurface the Shannon lenses coalesce into a broad sheet of backstepping sand bodies.
Campanian Shannon Sandstone
Authors: Bergman Katherine M. , Walker Roger G. 
Published: November 2010

Abstract
Recent interpretations of the lower Campanian Shannon Sandstone in the Powder River Basin, Wyoming have suggested that it was deposited in incised shorefaces of the falling stage and lowstand systems tracts rather than in offshore stacked shelf ridge complexes. A complete high resolution stratigraphic analysis of the Shannon requires that outcrops in the Bighorn and Powder River Basin be correlated with subsurface fields basinward. In the Hartzog Draw area where there is good core control, a consistent pattern of facies and erosion surfaces can be defined. From this pattern a template was constructed that could be used to interpret depositional patterns in uncored areas. The template consists of a regressive surface of erosion (RSE) that forms the base of an incised shoreface sandbody and a transgressive surface of erosion (TSE) that truncates the top of the sandbody and the RSE. Applying the template to the cross section suggests that six progradational successions and six transgressions can be defined within the Shannon. Positions of the RSEs and TSEs allow estimates of the magnitude of relative sea level fluctuations that controlled Shannon deposition (a few meters to 60 m). The correlations are consistent with the interpretation of the Shannon as incised shoreface sandbodies of falling stage and lowstand systems tracts, separated by mudstone deposits of the following transgressive systems tract.
An Expanded Model for Modern Shelf Sand Ridge Genesis and
Evolution on the New Jersey Atlantic Shelf
Authors: Snedden John W. , Kreisa Ronald D. , Tillman Roderick W. , Culver Stephen J. , Schweller William J. 
Published: November 2010

Abstract
The stepwise genesis and evolution of modern shelf sand ridges are investigated through chronostratigraphic analysis of four separate study sites on the New Jersey Atlantic shelf, ranging in depth from less than 4 meters (shoreface-attached ridge) to over 45 meters (detached ridge). Radiocarbon age-dated vibracores and high-resolution seismic surveys facilitated construction of a series of chronostratigraphic cross-sections of these 1 by 5 km-scale and greater ridges, which can range in vertical thickness to 10 meters. These data provide compelling support to an earlier morphodynamic model suggesting that shoreface-attached ridges may originate from ebb-tidal deltas and eventually detach from the shoreline during coastal transgression. A key element of the morphodynamic model involves cutting of the adjacent swale by an obliquely migrating tidal-inlet channel.
However, notable yet transitional differences exist between shoreface, nearshore, and offshore ridges in terms of age, microfaunal content, bathymetric profile, and cross-sectional area. This implies that ridges change considerably following coastal detachment. During this final phase, which we term ridge evolution, the ridges may migrate, change orientations, and possibly cannibalize earlier ridge and inlet-channel-fill complexes. This stage may be the most important in terms of what is preserved in the sedimentary record. Understanding the dynamic nature of these long-lived, transgressive shelf sand ridges may help resolve some of the debate regarding analogous ancient, stratigraphically-isolated marine sand bodies.
Sedimentary Facies and Genesis of Holocene Sand Banks on the East
Texas Inner Continental Shelf
Authors: Rodriguez Antonio B. , Anderson John B. , Siringan Fernando P. , Taviani Marco 
Published: November 2010

Abstract
Sediment cores and high-resolution seismic and side-scan sonar data were collected from four shelf banks on the east Texas inner continental shelf. Sabine, Heald, Shepard, and Thomas banks all have similar sediment facies, structure, and genesis. The banks are composed of three facies (top to bottom): A) an interbedded shell hash and sand unit; B) a muddy-sand unit characterized by a seaward-prograding and chaotic seismic facies, and C) an interbedded sand and mud unit characterized by landward-dipping seismic reflectors. These three sediment facies represent amalgamated storm beds, lower-shoreface or ebb-tidal delta, and back-barrier/flood-tidal delta environments respectively. Facies B and C were deposited during a time of relatively slow sea-level rise and were stranded on the shelf during a rapid sea-level rise. Facies A is the result of storms and wind-driven currents reworking the paleoshoreline deposits on the shelf. The banks are drowned paleo-shorelines restricted to the area above and immediately adjacent to the Trinity and Sabine incised fluvial valleys. This association is explained by the greater thickness of sands within the valleys (larger sources of sands), greater accommodation space, and greater subsidence rate within the valleys (greater preservation potential).
Sediment Transport in the Western Interior Seaway of North
America
Authors: Slingerland Rudy , Keen Hmothy R. 
Published: November 2010

Abstract
Whether from the foreshore, shoreface, shelf, or incised esruarine valleys, sedimentary deposits along the western edge of the Western Interior seaway quite uniformly record southerly directed paleoflows. Cardium Formation shoreface gravels at Willesden Green, Alberta, decrease in clast size to the southeast. Isoliths outlining clastic wedges, such as the Chalk Creek, are recurved to the south. Large-scale cross-strata in rocks considered to be either shelf sand ridges or detached shorefaces, such as the Kakwa and Musreau Members of the Cardium Formation and the Straight Cliffs Formation of southwestern Utah, indicate southerly directed paleocurrents. Estuarine incised valley-fills trend south or southeast, reflecting a high-stand shelf topography inherited by rivers as they cut across the inner shelf in response to a high-order sea-level drop. To explain this uniformity we conducted two numerical experiments that predict circulation and sediment transport paths in the seaway in response to 1) mean annual atmospheric forcing and 2) the passage of a mid-latitude winter storm. The mean annual forcing for the early Turonian is computed by GENESIS, an NCAR global climate model; the cyclone is computed using an idealized hurricane model. For the mean annual experiment, circulation of the seaway is computed using a three-dimensional, turbulent flow, coastal ocean model under the following initial and boundary conditions: 1) paleobathymetry according to a new interpretation of the litho- and bio-stratigraphy for the early Turonian; 2) fresh water runoff and precipitation-evaporation magnitudes as computed by GENESIS; 3) temperatures and salinities of the Boreal and Tethys Oceans based on GENESIS atmospheric temperatures; and 4) mean annual and daily wind stresses computed by GENESIS. For the storm experiment, circulation is forced solely by wind stresses.
Results show that these boundary conditions combine to produce a basin-wide counterclockwise gyre that arises from Coriolis acceleration acting on runoff jets trapped along the coast, abetted by latitudinal temperature and salinity gradients and a north-south, wind shear-couple. Individual storm events reverse the general circulation locally, but summed over a storm's duration, the storm-driven fluid and sediment transport augments the mean-annual transport of the gyre. Thus, net sediment transport directions along the western margin of the seaway, both on the shelf and in the wave-driven littoral zone, were southerly because the mean annual wind field, latitudinal temperature gradient, and fresh water runoff from land created a background circulation consisting of southerly geostrophic flow there. In addition, counterclockwise rotating, mid-latitude cyclonic storms passing southeastward over the central seaway drove a net southerly littoral drift in the foreshore and shore-parallel geostrophic flows whose net sediment transport was southerly. Along the eastern margin the computed shelf and littoral transport was to the north.