discontinuity surfaces clinoforms and facies architecture in a wave dominated shoreface shelf parasequence abstract detailed outcrop analysis of a wave dominated shoreface shelf parasequence exposed in the book cliffs utah reveals minor stratigraphic discontinuities which define clinoforms two types of discontinuity are recognized each with a distinctive lithologic character and geometry nondepositional discontinuities are marked by an abrupt decrease in the thickness and amalgamation of storm generated event beds and are interpreted to record hiatuses in sedimentation these discontinuities define clinoforms with a concave upward geometry that dip gently 0 02 0 58 over distances of 800 6000 m down depositional dip erosional discontinuities are marked by an abrupt increase in event bed amalgamation grain size and sand content and are interpreted as enhanced storm wave scours these discontinuities define more steeply dipping 0 22 0 95 concave upward clinoforms that extend over 100 1600 m down depositional dip and 500 1500 m along depositional strike the distribution and amalgamation of minor stratigraphic discontinuities defines linear zones of distinctive facies architecture that are oriented parallel to the paleoshoreline trend using the simple assumption that the shoreface shelf equilibrium profile remained approximately constant for each type of discontinuity throughout shoreface migration the bruun rule intra parasequence facies architecture can be speculatively interpreted in terms of shoreline trajectory which reflects the balance between sediment supply and accommodation the resulting interpretations support the notion that shoreline trajectory exerts a strong control on intra parasequence facies architecture and preservation of the shoreface shelf profile

impact of deltaic clinothems on reservoir performance dynamic studies of reservoir analogs from the ferron sandstone member and panther tongue utah subsurface reservoir models are typically limited by a lack of spatially accurate geometric data on bedform architecture and geometry these factors are key controls on fluid flow outcrop analogs have long been used as a source of such data but the capture of sufficiently precise outcrop data is a challenge the study presented in this article used highly accurate geometrical digital geological outcrop data collected using ground based laser scanning light detection and ranging lidar to build and test three dimensional geocellular models of deltaic reservoir analogs two well exposed ancient river dominated delta systems the panther tongue and the ferron sandstone member which both crop out in central utah were digitally mapped to precisely recreate their clinothem and clinoform geometries in geocellular reservoir modeling software such clinoforms are commonly draped with low permeability mudstones that produce reservoir heterogeneity by subdividing the deltaic sand body into a series of dipping sandstone beds clinothems a key aspect of the modeling was to accurately capture these geometries and their effect on simulated fluid flow portions of the two deltaic systems were dynamically analyzed in a reservoir modeling software by simulating production in 41 models these models tested a range of mudstone barrier continuities and permeabilities results quantify how the continuation of the heterogeneities governed the production rate and recovery factor in the panther tongue models mudstone permeability values were more important in the ferron sandstone models with steeper dipping and closer spaced clinothems although production was still influenced by the continuation of the heterogeneities

geometry and facies of tertiary clinothems spitsbergen sandstone clinothems from the battfjellet formation palaeogene on spitsbergen are locally exceptionally well preserved along depositional dip parallel mountainsides the clinothems are more than 1 km wide and more than 100 m thick superposition of several sandstone clinothems separated by mudstones reflects repeated shoreline progradation and transgression deposition took place partly on post transgressional depositional shelves and partly by contributing seaward sloping wedges or clinothems to a ramp progradation shorelines dominated both by mouth bar and shoreface environments have been identified the clinothems are organized into an overall progradational architecture with a geometry having features in common with progradational seismic facies

tracer and radionuclide sorption to vitric tuffs of busted butte nevada abstract field scale unsaturated zone tracer tests have been performed at busted butte nevada near the potential high level radioactive waste repository at yucca mountain these tests are intended to improve our understanding of unsaturated zone transport processes and to test our ability to predict field scale behavior using laboratory scale measurements the field tests use a mixture of nonreactive and reactive tracers nonreactive tracers include br i 5 different fluorobenzoic acids na fluorescein and a pyridone derivative reactive tracers include the metals li mn co and ni and the organic dye rhodamine wt rock samples from 3 different stratigraphic units at the busted butte test facility have been extensively characterized lithologically and mineralogically and analyzed for fe and mn oxide content sorption of np pu am and the field tracers onto these 3 rocks has been measured using batch techniques results confirm that the nonreactive tracers are indeed nonreactive and show that sorption of radionuclides and sorbing tracers increases with increasing degree of rock alteration as evidenced by increasing levels of smectite and fe and mn oxides among the radionuclides am and pu sorb much more strongly than np the tracers degree of sorption is rhodamine wt li mn

autogenic response of fluvial deltas to steady sea level fall implications from flume tank experiments flume tank experiments on fluvial deltas conducted with constant fall of relative sea level rate a 0 constant sediment discharge q s and constant water discharge q w reveal a built in geomorphic process that inevitably causes valley incision autoincision after the beginning of the sea level fall and forms paired stream terraces on the abandoned alluvial slope despite steady sea level fall deltas aggrade without major incision until the autoincision threshold is attained at which time the aggradational regime is replaced by a degradational one results of the experiments imply that multiple valley incision and terrace formation can occur as an autogenic response of the depositional system to steady forcing by constant sea level fall changes of a q s and q w or changes in river energy are not required to account for these geomorphic events the understanding of the autogenic response when combined with the theory of shoreline autoretreat provides an alternative view of the geomorphic development of fluviodeltaic systems during base level fall

sharp based flood dominated mouth bar sands from the burdekin river delta of northeastern australia extending the spectrum of mouth bar facies geometry and stacking patterns abstract distinguishing the deposits of mouth bars from delta distributary channels in the rock record may not be as straightforward as often portrayed because mouth bar deposits can be more variable than usually presumed mouth bars with triangular plan view subaerial geometry are well developed at the mouth of the modern burdekin river of northeastern australia this planform is intermediate between the elongate lozenge shaped mouth bars typical of river dominated deltas and the beach ridge geometries characteristic of wave dominated deltas surface and shallow subsurface bar deposits are predominantly moderately sorted coarse grained sand similar to that of adjacent lower delta plain channel floor sedimentary textures are modified at seaward sides of mouth bars by waves into a foreshore of well sorted fine to medium grained sand and mouth bar sands pass distally and laterally into more mud dominated lithologies the holocene section beneath the lower delta plain is dominated by 5 8 m thick sharp based bodies of coarse grained sand texturally indistinguishable from the modern mouth bar with no vertical grain size trend a slight upward fining trend or in a few cases a coarsening upward trend these sand bodies have low angle seaward dipping internal bedding surfaces and are bounded by surfaces of similar attitude the holocene burdekin delta was and is flood dominated rather than strongly wave influenced as proposed previously and prograded by rapid deposition of mouth bars during river floods most of which last for only a few days mouth bar construction takes place over tens of years the variable vertical grain size profiles of mouth bar deposits suggests formation by both aggradation and progradation and this is supported by the cross sectional geometry of mouth bar clinoform sets imaged geophysically once a mouth bar has become emergent and is stabilized by vegetation a new bar is initiated seaward in this way delta lobes are constructed over 100s to 1000s of years before being abandoned following an avulsion of the trunk river channel to another part of the delta caution is needed in the interpretation of ancient shallow water deltaic successions where sharp based fining upward mouth bar deposits may be confused with distributary channel facies

lithium sorption to yucca mountain tuffs the li ion has been used as a reactive tracer in field tests performed in the saturated and unsaturated zone in volcanic tuffs at yucca mountain nevada lithium sorbs weakly by cation exchange and permits field scale testing of laboratory based predictions of reactive solute transport a series of laboratory studies show that li sorption is nonlinear and varies with lithology in the different horizons of the tuff in particular both li sorption and li specific cation exchange capacity vary as functions of tuff mineralogy and can be predicted given quantitative x ray diffraction data these results indicate that li sorption is dominated by clay and zeolite minerals and that sorption coefficients can be predicted given mineralogic analysis results

unsaturated flow and transport through a fault embedded in fractured welded tuff 1 to evaluate the importance of matrix diffusion as a mechanism for retarding radionuclide transport in the vicinity of a fault located in unsaturated fractured rock we carried out an in situ field experiment in the exploratory studies facility at yucca mountain nevada this experiment involved the release of 82 000 l of water over a period of 17 months directly into a near vertical fault under both constant positive head at 0 04 m and decreasing fluxes a mix of conservative tracers pentafluorobenzoic acid pfba and bromide applied in the form of lithium bromide was released along the fault over a period of 9 days 7 months after the start of water release along the fault as water was released into the fault seepage rates were monitored in a large cavity excavated below the test bed after the release of tracers seepage water was continuously collected from three locations and analyzed for the injected tracers observations of bromide concentrations in seepage water during the early stages of the experiment and bromide and pfba concentrations in the seepage water indicate the significant effects of matrix diffusion on transport through a fault embedded in fractured welded rock

thrust loads and foreland basin evolution cretaceous western united states two dimensional modeling of loading during the formation of the idaho wyoming thrust belt shows that regional isostatic compensation by flexure of an elastic lithosphere is sufficient to control the formation of a foreland basin the flexural rigidity of the lithosphere is inferred to have been approximately 1023 nm 1030 dyne cm on the basis of palinspastic comparison of predicted downwarping due to the thrust plate loads to the shape of the sedimentary wedge on the west side of the cretaceous western interior seaway erosion of part of the uplifted thrust plates redistributed the load depositing it farther to the east thereby causing subsidence over a much wider area than could have been accomplished only by the loading by thrust plates paleotopography after major cretaceous thrust events was calculated the resulting mountainous terrain gentle alluvial plain and flat sea floor correspond well with the topography of the modern foreland thrust belt and basin system in the andes of south america and to paleogeographic reconstructions in the western united states thrust belt topography is controlled by the subsurface geometry of the thrust faults particularly the positions of ramp zones and by isostatic subsidence

kinematic evolution of a large offset continental normal fault system south virgin mountains nevada the south virgin mountains and grand wash trough comprise a mid miocene normal fault system that defines the boundary between the unextended colorado plateau to the east and highly extended crust of the central basin and range province to the west in the upper 3 km of the crust the system developed in subhorizontal cratonic strata in the foreland of the cordilleran fold and thrust system the rugged topography and lack of vegetation of the area afford exceptional three dimensional exposures compact stratigraphy and well defined prefaulting configuration of the rocks permitted a detailed reconstruction of the system reconstruction of cross sections based on more than 300 km2 of detailed mapping at a scale of 1 12 000 shows that the fault system accommodated more than 15 km of roughly east west directed miocene extension extension was initially accommodated on moderately to steeply dipping listric normal faults as the early faults and fault blocks tilted steeply to moderately dipping faults initiated within the fault blocks soling into the early faults some of the early faults were active at dips of 20 isostatically driven tilting is superimposed on tilting due to active slip and domino style rotation of the fault blocks collectively these processes rotated originally steeply dipping faults to horizontal orientations the kinematics are inconsistent with the widely accepted view that many near horizontal normal faults were rotated to their present orientations by later crosscutting normal faults however reexamination of other areas suggests that the evolutionary sequence seen in the south virgin mountains may in fact be widely applicable

terrestrial laser scanning in geology data acquisition processing and accuracy considerations terrestrial laser scanning or lidar is a recent innovation in spatial information data acquisition which allows geological outcrops to be digitally captured with unprecedented resolution and accuracy with point precisions and spacing of the order of a few centimetres an enhanced quantitative element can now be added to geological fieldwork and analysis opening up new lines of investigation at a variety of scales in all areas of field based geology integration with metric imagery allows 3d photorealistic models to be created for interpretation visualization and education however gaining meaningful results from lidar scans requires more than simply acquiring raw point data surveys require planning and typically a large amount of post processing time the contribution of this paper is to provide a more detailed insight into the technology data collection and utilization techniques than is currently available the paper focuses on the workflow for using lidar data from the choice of field area and survey planning to acquiring and processing data and finally extracting geologically useful data because manufacturer specifications for point precision are often optimistic when applied to real world outcrops the error sources associated with lidar data and the implications of them propagating through the processing chain are also discussed

quantitative outcrop data for flow simulation abstract an architectural analysis documents variations in bedding geometry and rock properties within a tide influenced deltaic sandstone exposed in the cretaceous frontier formation of central wyoming usa digital maps of bedding lithofacies and diagenetic cements as well as vertical logs of grain size lithofacies and permeability describe rock properties that potentially influence fluid flow behavior these records are used to construct simulation models that assess the relative importance of different types of geologic variability on prediction of subsurface fluid flow two 25 meter thick tide influenced deltaic sandstone bodies coarsen upward and contain inclined beds that reflect episodic delta front progradation decimeters to meters thick beds within bodies alternate between cross stratified sandstones formed during rapid flows and shales deposited during more quiescent conditions down depositional dip bed draping shales are more continuous and lithofacies within sandstone beds become finer grained and increasingly heterolithic as sandstone beds fine down dip mean permeability values decrease and coefficients of variation increase permeability values change from nearly normal distributions to highly right skewed and permeability values become more strongly spatially correlated nodular cements also affect permeability all of these variations were modeled using stratigraphic cornerpoint grids that preserve stratal geometry and gridblocks with properties assigned using a combination of rock property maps and statistical models based on rock property logs simulations predict effects on fluid flow of geologic heterogeneity at different scales the influences of process variables and the effects of different methods of grid construction and rock property assignment flow simulations of water flooding through a 22 m thick by 360 m long segment of a deltaic sandstone oil reservoir predict that 1 rapid flow through coarser grained deposits at the top of the sandstone body tends to draw water upward 2 thin shales draping sandstone beds shunt downdip directed flow downward and updip directed flow upward 3 cement nodules cause more tortuous flow patterns but have little effect on recovery efficiency 4 methods of predicting intrafacies correlation of permeability have little effect on flow behavior at this scale a simulation model constructed using a high resolution cartesian grid did not resolve the effects of inclined shales demonstrating the usefulness of stratigraphic cornerpoint grids for modeling flow through complex geologic deposits flow simulations of tracer flow through a meter thick cross stratified bed within the deltaic sandstone body showed that at this scale shale drapes and models of the intrafacies distribution of permeability have statistically significant effects

correlation techniques perforation strategies and recovery factors an integrated 3 d reservoir modeling study sirikit field thailand production in the sirikit oil field of the phitsanulok basin thailand commenced in 1982 the field has an stoiip stock tank oil initially in place of approximately 800 mmbbl million barrels to date more than 130 wells have been drilled and over 100 mmbbl produced reservoir management studies into optimizing recovery and identifying unswept oil volumes are ongoing so as to maximize the venture s profitability this work includes 3 d three dimensional static and dynamic modeling this study is one such exercise whereby different geological correlation techniques and perforation strategies were analyzed for their potential impact on recovery factors the sirikit field and adjacent satellite fields are composed of predominantly lacustrine mouth bar and fluvial deposits two correlation techniques lithostratigraphy and chronostratigraphy were employed to generate two 3 d reservoir architectures using the shell proprietary 3 d static reservoir modeling system geocap significantly different recovery factors are derived from 3 d dynamic flow simulation of these architectures no vertical upscaling 2 x 2 areal upscaling within the shell proprietary reservoir simulator mores when good quality sands observed on well logs are perforated in both models the lithostratigraphic correlation model results in an absolute 3 higher recovery factor than that of the chronostratigraphic correlation model in relative terms this represents a 43 higher recovery factor this suggests that if a lithostratigraphic correlation model is assumed then for this perforation strategy the recovery factor would be overestimated by 3 absolute and 43 relative if the chronostratigraphic interpretation represents the actual subsurface architecture in addition the architecture of the chronostratigraphic model results in the lateral correlation of the thicker upper mouth bar sands with good quality thin bedded toeset sands and shales heterolithics these thin bedded sands are only marginally resolvable on wireline logs and have not generally been perforated in the sirikit field when these thin bedded heterolithics are additionally perforated in the 3 d model an absolute increase in recovery factor of 2 is observed over the same model that has only the upper mouth bar sands perforated in relative terms this represents a 28 improvement in the recovery factor this work confirms and partially quantifies the impact that the choice of mouth bar correlation style can have on recovery factors as predicted by 3 d dynamic reservoir models however the chronostratigraphic model described in this paper represents an end member connectivity scenario whereby sand body continuity is relatively low due to continuous dipping shale barriers further work is required to quantify the recovery factors for the whole spectrum of potential chronostratigraphic model connectivity scenarios

digital outcrop models applications of terrestrial scanning lidar technology in stratigraphic modeling abstract laser ranging is extremely accurate and efficient terrestrial scanning lidar light detection and ranging applied to outcrop stratigraphic mapping enables researchers to capture laser range data at a rate of thousands of individual x y z and laser intensity points per second these data in conjunction with complementary remotely and directly sampled data are used to conduct high precision facies characterization and to construct 3d geological computer models outcrop data are presented here to explain our workflow and to discuss the construction of rock based 3d digital outcrop models doms reproducibility and quantification are the drivers of this methodology high resolution terrestrial lidar acquisition processing interpretation and visualization are discussed and applied to mapping of geological surfaces in three dimensions laser generated models offer scientists an unprecedented visualization medium in a quantitative 3d arena applications of this technology include constructing and visualizing complex 3d earth models from outcrops for improved reservoir modeling flow simulation in hydrocarbon and aquifer systems and property modeling to constrain forward seismic modeling

lowstand deltas in the frontier formation powder river basin wyoming implications for sequence stratigraphic models deposits of lowstand deltas formed on the floor of the cretaceous interior seaway of north america are found in the cenomanian lower belle fourche member of the frontier formation central wyoming sandstones located in similar distal basin locations hundreds of kilometers basinward of highstand shoreline deposits form important hydrocarbon reservoirs isolated within marine shales but interpretation of their origin has been highly controversial the distribution geometry and internal facies of these sandstones are documented by an extensive outcrop study and regional subsurface correlations to develop genetic facies models for these deposits this integrated record of lithofacies ichnofacies palynofacies paleocurrent data bedding relationships and isolith maps incorporates observations from nearly 100 measured outcrop sections and about 550 subsurface well logs four episodes of sediment progradation and subsequent transgression each left behind gradually upward coarsening deltaic sandstones that have eroded tops these deltaic sandstones have a lobate to elongate geometry basinward dipping internal clinoform bedding radiating paleocurrents a low to moderate degree of shallow marine burrowing and show variable wave influence and tidal influence on deposition delta plain paralic and nonmarine facies have been eroded from the top of deltaic successions erosion surfaces capping progradational deltaic successions are the only stratal discontinuities that can be mapped regionally and they appear to record transgressive ravinement enhanced over areas of structural uplift compared with lowstand surfaces of erosion which record the bypass of sediments basinward low accommodation during lowstands left little room for sandstones to stack vertically and successive episodes of delta progradation were offset along strike more tide influenced delta deposits formed within shoreline embayments begin page 262 defined by the topography of older wave influenced delta lobes and subtle syndepositional deformation of the basin floor standard sequence stratigraphic terminology is difficult to use in broad lowstand systems like the frontier formation because sandstones do not show simple vertical stacking patterns major stratal discontinuities can form by processes other than lowstand fluvial erosion and minor syndepositional deformation of the basin floor exerts a first order influence on depositional and sediment preservation patterns although many basin distal sandstones have been interpreted to be deposits of offshore bars shelf isolated valley fills and stranded shorelines the frontier formation examples documented here suggest that many of these deposits may be top eroded deltas formed where rivers delivered sediment to lowstand coastlines the external geometry and internal heterogeneities of hydrocarbon reservoirs found in these types of deposits reflect processes active on the low accommodation deltaic shoreline even in cases where subsequent ravinement has significantly truncated the deposits during transgression

anatomy of a transgressive lag panther tongue sandstone star point formation central utah the panther tongue of the star point formation in central utah contains a variety of transgressive lag deposits that when mapped regionally show a sensitive dependence upon pre existing topography of the palaeoshoreline the panther tongue consists of a coarsening upward sandstone wedge that prograded into the western interior seaway during late cretaceous santonian time high resolution sequence stratigraphic analysis revealed that this member was deposited during the long distance 50 km regression and transgression of a delta into shallow marine environments containing basal highstand forced regression lowstand and transgressive systems tracts based on grain size clast composition lateral extent and stratigraphic position the coarse sandstones on top of the panther tongue were classified into four types 1 simple 2 dispersed 3 oxidized and 4 local lags the simple lag is composed of dark grey coarse sandstone with oyster fragments and shark teeth this lag is typically extensively bioturbated and massive laminated and cross bedded units are also common this type of coarse sandstone is interpreted as a typical transgressive lag the dispersed lag differs in that it contains abundant mud and commonly occurs as multiple beds in thick intervals of muddy sandstone mixing of bay estuarine and shallow marine mud with simple lag sand may be responsible for deposition of this type of coarse sandstone the oxidized lag is distinctive in its reddish colour with extensive bioturbation and is commonly overlain by a simple lag the local lag is composed of thin bedded dark grey coarse sandstone occurring locally between the mouth bar and distributary channel the variation in types grain size and bed thickness of the coarse grained lags was mainly controlled by antecedent topography as suggested by immediately underlying lithofacies relatively thick 30 cm simple lags are present on top of mouth bar sandstones whereas dispersed lags are common on top of the distributary channel sandstone and in bay estuarine and shallow marine mudstones erosion of topographic highs mouth bar resulted in relatively thick accumulation of simple lags in topographic low areas such as distributary channel estuary bay and shallow marine environments fine grained muddy sands that were eroded from the nearby topographic highs were redeposited intermittent storm waves transported coarse sands both landward and seaward forming a dispersed lag the net effect was reworking of local topographic relief during overall transgression forming an apparently planar transgressive surface of erosion

geology and stratigraphy of fluvio deltaic deposits in the ivishak formation applications for development of prudhoe bay field alaska significant remaining reserves in prudhoe bay field are confined within deltaic rocks at the base of the triassic ivishak sandstone the initial stratigraphic characterization of the prudhoe bay reservoir was lithostratigraphically based and it depicted this basal reservoir interval as tabular zones between marine shale and overlying coarse grained fluvial sandstones a reassessment of this interval based on cores and genetic stratigraphic correlations depicts en echelon offlapping fluvially dominated deltaic wedges reservoir quality rocks occur in distributary mouth bar distributary channel and fluvial facies associations a paleogeographic reconstruction of one delta lobe includes an alluvial plain crossed by channels of possibly braided or low sinuosity rivers this alluvial plain graded into a delta plain cut by distributary channels that fed distributary mouth bars on a broad delta front river dominance is inferred from the abundance of unidirectional current structures normally graded beds soft sediment deformation and general absence of wave formed tidal and biogenic structures slumping and growth faulting locally replaced coarsening upward deltaic successions with sharp based overthickened mouth bar and distributary channel deposits mudstones deposited following delta lobe abandonment form laterally extensive flow barriers between lobes compartmentalization is most pronounced distally where deltaic sandstones are overlain by and pass laterally into marine shale proximally fluvial and deltaic sandstones are juxtaposed across erosional contacts improving reservoir continuity this stratigraphic interpretation is corroborated by production and surveillance data plus an interference test locally stratigraphy and poor waterflood performance reflect completions in diachronous sandstones that originated in separate deltaic lobes previously poor well performances were attributed to sandstone pinch outs in some cases production can be enhanced with recompletions rather than infill drilling nonconventional wells planned and completed with the benefit of detailed facies association correlations currently are recovering millions of barrels of previously bypassed oil

overlapping faults and their effect on fluid flow in different reservoir types a lidar based outcrop modeling and flow simulation study in this article we focus on the potential of fault overlap zones as conduits for fluid flow in a variety of reservoir types light detection and ranging lidar technology were applied to collect a three dimensional spatially constrained data set from a well exposed fault overlap zone that crops out in the devil s lane area of the canyonlands national park in utah a virtual outcrop was generated and used to extract structural and stratigraphic data that were taken into a reservoir modeling software and reconstructed the outcrop based model was flow simulated and used to test fluid flow through a real world fault overlap zone a structural framework was built based on collected outcrop data and combined with a series of nine different facies models the different facies models included an eolian model based on the outcrop and a range of synthetic fluvial and shallow marine systems results show that for certain depositional models cross fault reservoir communication may be poor despite the geometric connectivity of the relay beds this was the case for low net gross fluvial models and shoreface models conversely high net gross fluvial systems and eolian systems show good communication through the same relay zone overall the results show that in the presence of a fault overlap zone pressure communication across a relay ramp may still be poor depending on the scale of the faults and relay ramp as well as the geometry and volume of the sands

quantifying clinothem geometry in a forced regressive river dominated delta panther tongue member utah usa this study presents a methodology for the quantitative description of small scale delta clinothems the quantitative bed data analysis is based on three dimensional virtual outcrop models generated by ground based laser scanning light detection and ranging a large number of clinothem bed measurements have been collected from the ancient forced regressive delta system of the panther tongue that crops out in utah usa in river dominated marginal marine environments clinothems separated by clinoform surfaces represent the former position of the delta front as it prograded systematic collection of data from virtual outcrop models has allowed for accurate spatially constrained measurement of individual bed thicknesses and the compilation of a detailed database on clinothems and associated clinoform geometries measurement locations were selected so that each measurement was 10 m down depositional dip from the previous one the study area covers 5 km2 within which 2376 measurements were made from 50 separate clinothems in 320 different positions within the virtual outcrop a bed taper parameter permitted the thinning of the clinothems to be described as a single number and thus allowed relative comparison between beds combined measurements were also used to calculate the average dip angle of the clinothems analysis of the vertical and lateral stacking of the clinothems has revealed a series of stratigraphic cycles which are termed bedsets stream mouth bars the surfaces that bound the bedsets are unremarkable and it is unlikely that their significance would be recognized without this style of detailed analysis a cyclic depositional pattern interpreted as related to autocyclic processes and compensational stacking of mouth bars is proposed as the origin of these packages mapped length thickness trends constrain the spread of these variables and can be used to constrain subsurface models of analogous hydrocarbon reservoirs

thick turbidite successions from supply dominated shelves during sea level highstand emphasis on the association between relative sea level lowstand and the formation of sandy deep water fans has tended to downplay the significance of high sediment supply and its potential to create deep water fans even during sea level highstands the lance fox hills lewis shelf margin in southern wyoming suggests that high supply was critical in causing the accretion of this moderately wide maastrichtian shelf margin at a minimum rate of 47 8 km m y and the generation of large sand rich fans during every shoreline regression across the shelf it is surprising that fans developed from shelf margin clinoforms that show systematically rising shelf edge trajectories proxy for rising relative sea level as well as from those that show flat trajectories stable to falling relative sea level however the latter producing more sediment bypass resulted in bigger and thicker fans whereas the former produced somewhat smaller and thinner fans we term the former highstand fans and suggest caution in using the lowstand model for high supply systems