sediment dispersal and quantitative stratigraphic architecture across an ancient shelf two large 200 to 300 km near continuous outcrop transects and extensive well log data ca 2800 wells allow analysis of sedimentological characteristics and stratigraphic architecture across a large area ca 60 000 km2 of the latest santonian to middle campanian shelf along the western margin of the western interior seaway in eastern utah and western colorado usa genetically linked depositional systems are mapped at high chronostratigraphic resolution ca 0 1 to 0 5 ma within their sequence stratigraphic context in the lower part of the studied interval sediment was dispersed via wave dominated deltaic systems with a compound clinoform geomorphology in which an inner wave dominated shoreface clinoform was separated by a muddy subaqueous topset from an outer clinoform containing sand poor gravity flow deposits these strata are characterized by relatively steep net regressive shoreline trajectories 0 1 with concave landward geometries narrow nearshore belts of storm reworked sandstones 2 to 22 km wide offshore mudstone belts 250 km and relatively high sediment accumulation rates ca 0 27 mm year 1 the middle and upper parts of the studied interval also contain wave dominated shorefaces but coeval offshore mudstones enclose abundant isolated tide influenced sandstones that were transported sub parallel to the regional palaeoshoreline by basinal hydrodynamic tidal circulation these strata are characterized by relatively shallow net regressive shoreline trajectories 190 km and relatively low sediment accumulation rates ca 0 11 mm year 1 the change in shelfal sediment dispersal and stratigraphic architecture from i compound clinoform deltas characterized by across shelf sediment transport to ii wave dominated shorelines with isolated tide influenced sandbodies characterized by along shelf sediment transport is interpreted as reflecting increased interaction with the hydrodynamic regime in the seaway as successive shelfal depositional systems advanced out of a sheltered embayment utah bight this advance was driven by a decreasing tectonic subsidence rate which also suppressed autogenic controls on stratigraphic architecture

correlation and provenance of upper cretaceous campanian fluvial strata utah u s a from zircon u pb geochronology and petrography abstract detrital zircon and petrographic provenance analysis of upper cretaceous campanian strata corroborate correlation of the fluvial kaiparowits formation in southern utah with post castlegate strata of the mesaverde group in eastcentral utah sandstone samples of the kaiparowits formation in the kaiparowits plateau and mesaverde group neslen bluecastle tongue of castlegate farrer and tuscher formations in gray canyon north of green river utah contain six u pb detrital zircon age populations ranging in age from archean to late cretaceous thrust belt derived sublitharenite and quartzarenite of the lower part of the mesaverde group neslen and bluecastle lack or have only rare mesozoic grains but contain abundant archean proterozoic and paleozoic grains that record recycling of proterozoic paleozoic and jurassic sandstones exposed in uplifted thrust sheets to the west south and southwest derived feldspathic litharenite of the kaiparowits and farrer formations contains proterozoic grains and a diverse population of mesozoic grain ages archean grains are rare to absent maximum depositional ages interpreted from young zircon grains in two kaiparowits samples statistically overlap 40ar 39ar ages 76 74 ma from interbedded bentonitic tuffs and weighted mean ages of young grains from the farrer formation kolmogorov smirnoff statistics in conjunction with young grain ages and detrital age spectra corroborate petrographic evidence which indicates that the kaiparowits rivers were connected northward with a river system that deposited the farrer formation the young grain ages although imprecise indicate that the uppermost mesaverde group strata of the tuscher formation are younger than the kaiparowits formation and record partitioning of the former foreland basin by laramide uplifts

tectonic control of nested sequence architecture in the castlegate sandstone upper cretaceous book cliffs utah abstract the castlegate sandstone at its type section price canyon near price utah encompasses a single stratigraphic sequence spanning approximately 5 m y it includes a sandstone member corresponding to a lowstand systems tract consisting of braided fluvial sheet sandstones and a mudstone member in which shales are more abundant and some evidence of tidal influence is present this is the transgressive to highstand systems tract from near trail canyon eastward the mudstone member passes laterally into the sego sandstone and neslen formation a succession of at least six higher frequency sequences of fluvial estuarine origin the buck tongue a marine shale unit separating the castlegate sandstone and the sego sandstone east of green river is erosionally truncated below the sego sand tone northwest of trail canyon we suggest that the origin of the sequences is related to flexural loading and intraplate stress on two time scales eustasy cannot be ruled out but there is no independent evidence for this process the main 5 m y sequence reflects regional tectonism with the sandstone member developing at a time of slow subsidence and the mudstone member reflecting a higher long term subsidence rate the higher order sequences nested within the third order sequence east of trail canyon are interpreted as a basinal response to episodes of crustal shortening on a 105 yr time scale this study amplifies the model of posamentier and allen 1993a in which ramp type foreland basins are divided into areas of rapid and slow subsidence zones a and b we postulate that these zones migrated asinward and landward in response to variations in long term subsidence rate an effect not predicted in the original model and can be mapped by reference to the distribution of type 1 sequence boundaries in the higher order sequences differences in sequence architecture east and west of trail canyon may have been amplified by differences in crustal rheology the sequence architecture changes at the boundary of the underlying paleozoic paradox basin a zone of nw se oriented folds faults and salt diapirs which we suspect were reactivated by cretaceous tectonism the high frequency sequences are within the area of the paradox basin an area that may have been more prone to vertical structural movements in response to intraplate stresses incipient uplift of laramide structures may also have modified fluvial patterns and controlled the orientation of incised valleys on several of the sequence boundaries

an experimental and numerical study of the microstructural parameters contributing to the seismic anisotropy of rocks 1 the elastic properties of rocks are influenced by several microstructural variables including the lattice preferred orientation and grain shape fabric of the mineral phases variations in the spatial distribution of the mineral phases the properties of the grain boundaries and the presence of porosity fractures consequently in principle directional variations in these variables can be inferred from seismic velocity anisotropy observations experimental seismic velocity measurements made on rocks of well characterized microstructure may be used to improve the quality of such interferences however since most rocks are microstructurally complex in order to interpret the measurements fully theoretical analyses which can accommodate all the relevant microstructural variables are required theoretical analyses of the requisite sophistication have only recently been developed we have tested one of these due to ponte castaneda and willis by using it to calculate the elastic properties of an upper mantle harzburgite and by then comparing the results with experimental velocity measurements to determine if the values of those microstructural variables which are difficult to quantify grain boundary properties fracture shape are physically realistic we find that they are and conclude that the ponte castaneda and willis analysis provides a powerful method for a more detailed assessment of the causes of elastic property anistropy in rocks than has previously been possible

paleogeographic controls of coal accumulation cretaceous blackhawk formation and star point sandstone wasatch plateau utah analysis of sequences associations and relationships of facies in the upper cretaceous blackhawk formation and star point sandstone in the wasatch plateau utah leads to inferences regarding the paleogeographic controls affecting the accumulation of coals in delta barrier island complexes progradation lateral shifting and abandonment of these complexes created four major landward thinning tongues of the upper sandstone bed of the star point sandstone that extend into the lowermost blackhawk formation each tongue of the star point sandstone trends northwest to southeast subparallel to the general orientation of the late cretaceous paleoshoreline and represents accretion ridge distributary channel and mouth bar sandstones the accretion ridge or barrier island sandstones grade landward into coastwise lagoonal and back barrier swamp deposits which in turn merge with bayhead deposits of short headed streams these deposits grade laterally into delta plain deposits that consist of major distributary channels which crosscut the coastwise lagoons two coal populations were formed in this paleogeographic setting delta plain and back barrier coals delta plain coals formed as thin to thick discontinuous bodies back barrier coals are thicker and more laterally continuous they parallel depositional strike and accumulated in swamps on surfaces of infilled lagoons here the swamps were sites of accumulation of thick coals and were influenced by abandonment of associated deltaic barrier island complexes successive offlap events resulted in accumulation of the hiawatha coal not as a single continuous bed but as a series of discontinuous related coal bodies

fabric related seismic anisotropy in upper mantle xenoliths evidence from measurements and calculations the seismic properties and their directional dependence have been measured in four mantle peridotites from picritic tuffs vitim baikal region russia geothermobarometric data suggest a source depth for the xenoliths corresponding to the spinel garnet transition zone 40 90km the experimental data include the measurement of p and s wave velocities and densities at confining pressures to 600 mpa and temperatures to 600 c and the determination of velocity anisotropy and shear wave splitting the measured velocities are compared with velocity calculations based on lattice preferred orientation lpo of olivine orthopyroxene the modal composition of the rocks and the single crystal stiffness coefficients macroscopic velocity anisotropy is strongly controlled by the lpo of olivine measured 600 mpa room temperature and calculated p wave anisotropies compare fairly well although the experimentally determined velocities are markedly lower than the calculated velocities the correspondence between measured and calculated shear wave splitting data is less pronounced this is attributed to grain boundary effects retrogressive reactions interstitial glass incomplete crack closure and to the fact that the lpo of the cpx fraction has not been included in the calculation the magnitude of p wave anisotropy corresponds to that observed in mantle peridotites exposed at the surface ivrea zone northern italy ronda southern spain

migration of dynamic subsidence across the late cretaceous united states western interior basin in response to farallon plate subduction backstripped cross sections of the late cretaceous succession across central utah colorado and southern wyoming in the western interior basin united states reveal a component of continuously evolving long wavelength residual subsidence in addition to subsidence driven by the sevier thrust belt and associated sediment loads the loci of maximum rates of this residual subsidence moved eastward from ca 98 to 74 ma in phase with the west to east passage of the farallon slab as reconstructed from tomography based on quantitative inverse models these new subsidence data allow testing of existing subduction models and confi rm the dynamic subsidence origin of the western interior basin furthermore regional variations in subsidence rates suggest a possible defi cit of negative buoyancy mantle loading inside the slab beneath colorado supporting the hypothesis that the thickened slab represents a subducted oceanic plateau this paper documents how the cretaceous stratigraphy records the timing patterns and position of underlying mantle processes during farallon slab subduction the new data also reveal patterns indicative of the commencement of the laramide orogeny in the western united states

depositional and stratigraphic architecture of the santonian emery sandstone of the mancos shale implications for late cretaceous evolution of the western interior foreland basin of central utah u s a abstract the santonian emery sandstone member of the mancos shale is a continental to shallow marine succession that prograded into the cretaceous western interior seaway of western north america sediment sourced from the uplifted sevier orogen to the west fed a shoreline in the adjacent subsiding north south trending foredeep these sandstones are now superbly exposed along a 120 km long strike parallel continuous outcrop in the cliffs of the wasatch plateau of central utah shoreface parasequences are composed of coarsening upward successions of hummocky cross stratified and intensely bioturbated sandstones indicating deposition at a storm dominated shoreline two distinct depositional complexes record eastward and northeastward shoreline progradation at the northern and southernmost extremities of the plateau respectively in the subsurface emery strata comprise a thick succession of coal bearing coastal plain deposits the emery sandstone records a period of long term paralic progradation to aggradation containing at least 17 parasequences arranged into three 600 kyr regressive transgressive cycles that are recognizable in both complexes each cycle comprises only highstand and transgressive systems tracts and erosional sequence boundaries are absent absence of erosional sequence boundaries is attributed to high rates of subsidence in the foreland basin at this time santonian glacio eustatic sea level fluctuations are proposed to account for the high frequency cyclicity whilst longer term aggradation may be a function of organic controls on shoreface stacking patterns by immobile raised coal mires lying landward of the shorefaces when placed in a temporal and spatial context the emery sandstone provides a missing link in the understanding of long term controls on late cretaceous depositional systems in the central utah segment of the foreland basin and allows inferences to be made regarding foreland basin dynamics in particular thrust tectonics is postulated to have played a major role in governing the architecture of late cretaceous strata in central utah marked along strike thickening of the emery sandstone in particular is attributed to long lived elevated rates of subsidence in northern utah and southern wyoming during the late cretaceous that is adjacent to concentrated zones of thrust nappes a north dipping depositional slope is inferred from this subsidence distribution aligned approximately parallel to the structural grain of the hinterland load northeastward progradational directions of successive turonian santonian and early campanian regressive wedges in this part of the western interior basin are attributed to the presence of this tectonically induced regional slope gradient sediment sourced to these late cretaceous shorefaces is likely to have been sourced through structural recesses within the thrust front resulting in a spatial alignment of several successive regressive wedges and implicates an important long lived kinematic control on sediment supply of late cretaceous regressive wedges only the emery sandstone does not temporally coincide with reported periods of active thrusting suggesting that the regression was a consequence of factors other than uplift related elevated rates of sediment supply

integrating sandstone petrology and nonmarine sequence stratigraphy application to the late cretaceous fluvial systems of southwestern utah u s a abstract petrographic and dispersal data are essential to correct interpretation of mechanisms that create continental sequence stratigraphic architecture a case study from southern utah demonstrates that upper cretaceous upper santonian campanian alluvial successions in the southernmost part of the cordilleran foreland basin were deposited by fluvial systems of contrasting drainage directions and provenance and suggests that different mechanisms governed their sequence architecture most of the rivers flowed northeast subparallel to the basin foredeep less common fluvial systems flowed to the east southeast the fluvial sandstones fall naturally into four petrofacies 1 quartzofeldspatholithic mean qt61f19l20 2 feldspatholithic qt29f19l52 3 quartzolithic qt75f6l20 and 4 quartzose qt99f1l1 petrofacies 1 and 2 were derived from mixed supracrustal and basement sources to the southwest and south respectively whereas petrofacies 3 and 4 were derived from uplifted thrust sheets of the sevier orogenic belt to the southwest and west respectively only the east southeast flowing rivers transported the quartzose petrofacies the fluvial strata which include the uppermost straight cliffs wahweap and kaiparowits formations form two large scale stratigraphic successions typically interpreted as continental stratigraphic sequences hundreds of meters thick each succession begins with an amalgamated braided fluvial deposit grades to mudstone rich strata with low sandstone body connectivity and culminates in highly connected sandstone bodies with multistory stacking the basal amalgamated deposits of each succession are architecturally similar but their compositional and dispersal characteristics are different quartzofeldspatholithic quartzolithic and quartzose sandstones above the lower base level shift are variable but generally similar in compositional and dispersal characteristics to both underlying and overlying strata a phenomenon termed here congruence in contrast quartzose amalgamated fluvial sandstone above the upper base level shift differs sharply in composition and dispersal direction from underlying and overlying lithic rich strata the foredeep axis controlled the progradation direction of the congruent shift which was likely driven by climatically induced sediment influx a eustatic fall or both in the case of the incongruent shift increased sediment supply permitted the rivers to cross the foredeep temporal association of the upper amalgamated deposit with active structures in the thrust belt and foreland basin indicates that syntectonic thrust uplift not isostatic uplift or climate caused the influx of quartz

no change in fluvial style across a sequence boundary cretaceous blackhawk and castlegate formations of central utah u s a nonmarine sequence stratigraphic models are based largely on studies of fluvial units in the cretaceous western interior of north america including the blackhawk and castlegate formations of central utah these models suggest that fluvial units should show a transition from mudstone prone isolated meander belt deposits of the transgressive and highstand systems tract into amalgamated braided stream sandstones of the lowstand systems tract these mudstone rich fluvial strata are largely assumed rather than documented to represent the deposits of isolated meander belt deposits despite recent work that suggests that there is no simple relationship between the proportion of preserved floodplain mud and fluvial style there are numerous studies documenting the braided character of the sandstone rich castlegate formation but there are no corresponding studies that document the internal fluvial facies architecture within the blackhawk formation to support the interpretation that the blackhawk comprises the deposits of a meandering stream system we test the validity of the sequence stratigraphic model by comparing dimensions and styles of associated bar and channel deposits as well as cross stratal thicknesses between the blackhawk and castlegate formations along salina canyon in utah data compiled from 24 measured sections and 6 photomosaics show that the blackhawk formation comprises isolated sandy channel belt sheet sandstones 5 8 m thick contained within thick floodplain mudstones whereas the castlegate formation consists of about 80 m of amalgamated sandy channel belt sheets 4 7 m thick with only minor mudstone the average height of cross sets is 13 cm in the castlegate formation and 14 cm in the blackhawk formation and formative dune height is estimated to be 38 cm for the castlegate formation and 45 cm for the blackhawk formation average bar accretion thicknesses are 2 m in both the blackhawk and castlegate formations corresponding water depths are estimated to be 2 5 4 1 m for the blackhawk and 2 3 3 8 m for the castlegate the correlation of master bedding planes in the blackhawk formation shows overlapping lens shaped bar deposits and channel fills bar tops appear to dip in several directions indicating both lateral and downstream accretion of mid channel braid bars while there is some indication that castlegate rivers were slightly shallower the differences do not suggest a major change in fluvial style across the sequence boundary both are braided the lack of change in scale of channels also is not compatible with a hypothesized increase in aridity between the blackhawk and the castlegate the difference in fluvial architecture between the two formations is interpreted to reflect changes in accommodation that were likely tectonic in origin this supports that idea that preservation of thick successions of fine grained overbank material is not a function of the plan view channel geometry

correlating mechanical data with microstructural observations in deformation experiments on synthetic two phase aggregates abstract a simple method of analysing the results of deformation experiments on synthetic two phase aggregates is presented and applied to some tests on calcite halite aggregates the approach involves replacing the observed mechanical behaviour of real two phase materials of coarse microstructure with a phase volume fraction weighted mechanically equivalent representation in which each phase is assigned its own single valued stress and its own single valued strain such a representation can be solved for the stresses and strains in the two phases and the results compared with the stresses and strains as determined from the deformation microstructures in principle it is then possible to constrain which of the features of the microstructure are mechanically significant the stresses supported by the synthetic calcite halite aggregates suggest a strong partitioning of the deformation into the halite at all volume fractions of calcite and yet analysis of the halite strains from the deformation microstructures indicates that there is little or no strain partitioning between the phases however these conflicting results may be reconciled by using the calcite contiguous volume rather than the actual calcite volume fraction to characterize the strength of the aggregates with respect to those of their component phases

quartz preferred orientation in naturally deformed mylonitic rocks montalto shear zone italy a comparison of results by different techniques their advantages and limitations in the geologic record the quartz c axis patterns are widely adopted in the investigation of crystallographic preferred orientations cpo of naturally deformed rocks to this aim in the present work four different methods for measuring quartz c axis orientations in naturally sheared rocks were applied and compared the classical universal stage technique the computer integrated polarization microscopy method cip the time of flight tof neutron diffraction analysis and the electron backscatter diffraction ebsd microstructural analysis and cpo patterns of quartz together with the ones obtained for feldspars and micas in mylonitic granitoid rocks have been then considered to solve structural and geological questions related to the montalto crustal scale shear zone calabria southern italy results obtained by applying the different techniques are discussed and the advantages as well as limitations of each method are highlighted importantly our findings suggest that patterns obtained by means of different techniques are quite similar in particular for such mylonites a subsimple shear 40 simple shear vs 60 pure shear by shape analysis of porphyroclasts was inferred a general tendency of an asymmetric c maximum near to the z direction normal to foliation suggesting dominant basal slip consistent with fabric patterns related to dynamically recrystallization under greenschist facies is recognized rhombohedral slip was likely active as documented by pole figures of positive and negative rhombs tof which reveal also potential mechanical dauphine twinning results showed that the most complete cpo characterization on deformed rocks is given by the tof from which also other quartz crystallographic axes can be obtained as well as various mineral phases may be investigated however this use is restricted by the fact that a there are very few tof facilities around the world and b there is loss of any domainal reference since tof is a bulk type analysis ebsd is a widely used technique which allows an excellent microstructural control of the user covering a good amount of investigated grains cip and us are not expensive techniques with respect the other kind of investigations and even if they might be considered obsolete and or time consuming they have the advantage to provide a fine and grain by grain first round inspection on the investigated rock fabric

spatial and temporal evolution of coastal depositional systems and regional depositional process regimes campanian western interior seaway u s a abstract this paper provides a critical review and regional synthesis of late cretaceous shallow marine deposits along part of the western margin of the western interior seaway of north america which contains the most extensively documented outcrop based studies of siliciclastic coastal depositional systems in the world the results of this synthesis are presented in the form of paleogeographic maps covering present day new mexico utah colorado and wyoming usa for five timeslices in the campanian these maps are used to evaluate the spatial and temporal evolution of regional depositional process regimes along a large 1000 m stretch of coastline the evolution of regional depositional process regimes is linked to tectonic and paleoceanographic controls on the western interior seaway which enables the results of this synthesis to be applied to prediction of depositional process regimes in other less intensively studied basins six gross depositional environments have been mapped for each timeslice 1 alluvial to coastal plain sandstones 2 coastal plain coals mudstones and sandstones 3 shoreline sandstones 4 marine mudstones 5 gravity flow siltstones and sandstones and 6 marine marls and chalk shoreline sandstones in each timeslice are interpreted in further detail using documented evidence for the three principal classes of depositional process wave tidal and fluvial and published reconstructions of coastal morphology which is widely considered to reflect depositional process regime based on these interpretations shoreline sandstones are assigned to five categories of depositional process regime 1 regressive wave dominated shorefaces and delta fronts 2 regressive river dominated delta fronts 3 regressive mixed tide and wave influenced delta fronts 4 regressive tide dominated delta fronts and 5 transgressive barrier islands back barrier lagoons and estuaries the accuracy of and uncertainty in classification of depositional process regime are critically evaluated additionally stratal thickness and sediment routing pathways have been interpreted in order to assess the impact of tectonic and paleoceanographic controls on spatial and temporal changes in all of the evaluated shallow marine successions thin tide influenced intervals were deposited in back barrier and lagoon systems associated with net transgressive shorefaces and estuaries however it is notable that all preserved tide dominated and tide influenced regressive deltaic systems are located along the northern margin of the utah bight a tectonically related embayment that had a pronounced expression during the middle campanian the southern margin of the embayment and coastlines to the north are conspicuously more wave dominated which supports their exposure to a larger wave fetch in contrast the northern margin of the embayment was relatively wave protected it is concluded that tidal range was amplified due to resonance of the principal semidiurnal tide in the strongly embayed geometry of the middle campanian utah bight

sediment supply dominated stratal architectures in a regressively stacked succession of shoreline sand bodies campanian desert member to lower castlegate sandstone interval book cliffs utah colorado usa

stratigraphic architecture and hierarchy of fluvial overbank splay deposits splay deposits represent an important sand prone component of the otherwise fine grained stratigraphic record of fluvial overbank systems this work presents a hierarchical approach to the classification and palaeoenvironmental interpretation of ancient preserved splay deposits supported by the analysis of the stratigraphic architecture of 11 exhumed examples from the jurassic morrison formation and the cretaceous mesaverde group western usa and analysis of the morphology of splays from nine modern fluvial systems a hierarchical arrangement of splay deposits is proposed categorized into lithofacies beds elements and complexes recognition criteria for each tier of the hierarchy include identification of bounding surfaces thinning and fining trends of splay elements and complexes and palaeocurrent variability progradational and compensational stacking trends control the stratal architecture of splay deposits and these are influenced by the following factors 1 the rate of local accommodation generation which influences the erosive power of floodwaters and whether splay elements are laterally offset owing to compensational stacking 2 the nature of the topographic confinement of the floodplain 3 the preservation potential linked to migration direction of channel splay bodies can contribute volume to fluvial reservoirs and may form significant connectors that link otherwise isolated primary channel bodies thereby enhancing reservoir connectivity supplementary material thickness and facies types with global positioning system gps coordinates length and width v thickness and modern data and coordinates are available at https doi org 10 6084 m9 figshare c 4461026

late cretaceous fluvial megafan and axial river systems in the southern cordilleran foreland basin drip tank member of straight cliffs formation and adjacent strata southern utah u s a abstract the upper cretaceous lower campanian drip tank member of the straight cliffs formation in the grand staircase region of southern utah is an upward coarsening sandstone rich low sinuosity fluvial deposit in the cordilleran foreland basin the drip tank member thins from 75 m to 30 m eastward across the basin foredeep approximately parallel to its dominant eastward sediment dispersal direction and thins southward along the foredeep to as little as 17 m near its southern outcrop extent along modern cliff lines it overlies and underlies mudstone rich fluvial strata of the john henry member of the straight cliffs formation and lower member of the wahweap formation respectively both of which were deposited by northeast flowing rivers the john henry drip tank contact lies in an interfingering progradational stratigraphic transition from medium grained lenticular sandstone bodies to tabular coarse grained amalgamated sandstone bodies the contact with the overlying wahweap formation is locally a prominent surface of erosion or sediment reworking sandstone petrography and detrital zircon age populations of the strata indicate detrital sources in basement south of the foreland basin thrust sheets to the west and magmatic arc rocks to the southwest the uppermost part of the john henry member contains as much as 10 feldspar and abundant 1 84 1 60 ga detrital zircons derived from yavapai mazatzal basement rocks in the mogollon highlands the drip tank member ranges from quartzarenite to chert bearing sublitharenite with grenville 1 2 1 1 ga neoproterozoic and early paleozoic detrital zircons derived from proterozoic through jurassic strata exposed in the sevier orogenic belt lower member wahweap litharenites contain abundant thrust belt derived detrital carbonate grains absent from compositionally mature drip tank sandstones as well as a broad range of zircon ages the drip tank member constitutes deposits of a sand rich fluvial megafan or distributive fluvial system that displaced a subjacent but partly time equivalent axial fluvial system eastward as the megafan driven in part by seasonally high discharge fed by monsoonal precipitation prograded across the basin foredeep a thick amalgamated fan axis succession present in northern exposures contrasts with a thinner fan flank succession in southern localities tabular sixth order lithosomes each containing channels on the order of 7 m deep define three individual fluvial fans or fan lobes in the megafan system younger wahweap fluvial channels eroded uppermost drip tank deposits of the fan axis and fan flank transverse fan progradation across the foredeep recorded falling accommodation sediment supply in an aggradational to progradational systems tract erosion and reworking of the upper fan surface record decreased accommodation sediment bypass and erosion prior to reoccupation of the foredeep by the wahweap axial fluvial system the upper contact of the drip tank member is thus the primary sequence boundary in this multi component fluvial system and the lower wahweap represents transitional systems tract deposits accumulated as accommodation sediment supply increased

high resolution linkage of channel coastal plain and shallow marine facies belts desert member to lower castlegate sandstone stratigraphic interval book cliffs utah colorado usa

an olivine fabric database an overview of upper mantle fabrics and seismic anisotropy we present a unique database of 110 olivine petrofabrics and their calculated seismic properties the samples come from a variety of the upper mantle geodynamic environments ophiolites subduction zones and kimberlites with a wide range of micro structures a phenomenological relationship is established between p and s wave seismic anisotropy and the degree of crystal alignment fabric strength seismic anisotropy increases rapidly at low fabric strength before reaching a near saturation level of 15 to 20 for p waves and 10 to 15 for s waves despite a large variation in the symmetry of fabric patterns the average seismic properties of the different fabric micro structural and geodynamic settings have similar anisotropies in both magnitude and symmetry hence it would seem possible to determine some measure of fabric strength from seismic anisotropy if the dimensions of the anisotropic region are known but not geodynamic environment or details of the petrofabric pattern a simple pattern of seismic anisotropy characterises the average sample of the database which has the following features the polarisation plane of the fastest s wave is parallel or sub parallel to the foliation plane the maximum shear wave splitting is parallel to the y structural direction in foliation plane and normal to the lineation the maximum of the p wave velocity is parallel to the high concentration of 100 axes which is sub parallel to the lineation the 100 orientation distribution has the greatest influence on the p wave seismic anisotropy the 100 and 001 orientation distributions have the greatest influence on the symmetry of s wave anisotropy although the magnitude of anisotropy is influenced by the distribution of all three principal axes although the database only contains olivine petrofabrics this statistical study clearly shows that seismic anisotropy can be used to deduce the orientation of the structural frame in the upper mantle 1998 elsevier science b v all rights reserved

hardness toughness and modulus of some common metamorphic minerals studies of the hardness and toughness of minerals have historically focused on minerals of the mohs scale although with the exceptions of quartz orthoclase and calcite mohs phases are not common rock forming minerals we report new hardness h toughness resistance to fracture k ic and indentation modulus e data obtained by microhardness and depth sensing indentation dsi or nanoindentation experiments for common metamorphic minerals sillimanite kyanite andalusite garnet quartz and orthoclase feldspar because the experimental techniques involve indentation induced cracking as well as depth sensing indentation the new data set can be used to investigate a range of plastic behavior for minerals in the crust and mantle the three al2sio5 polymorphs have similar h values 10 12 gpa kyanite has the largest values and andalusite the smallest these values are similar to that of quartz 12 gpa and greater than that of orthoclase 7 gpa garnet h values vary with composition for grossular h 13 gpa and for almandine pyrope h 15 gpa although h values for the minerals we analyzed span a range of 10 gpa most fracture toughness values are between 1 1 8 mpa m garnet is much harder than al2sio5 but has a similar to slightly lower k ic grossular 1 2 mpa m almandine pyrope 1 4 mpa m andalusite 1 8 mpa m sillimanite 1 6 mpa m kyanite k ic is difficult to measure owing to the ease with which kyanite cleaves garnet has properties similar to those of cubic zirconia zro2 which we measured as a reference another reference mineral periclase mgo has the lowest h 5 gpa and the highest k ic 4 mpa m of minerals we measured among the silicates e varies significantly from orthoclase 89 gpa to quartz 117 gpa to garnet 245 260 gpa and al2sio5 has intermediate values kyanite 186 253 gpa sillimanite 207 gpa andalusite 232 gpa

residual stress measurements on a quartz vein a constraint on paleostress magnitude 1 the residual stress in a quartz vein from a metamorphic province is evaluated by an x ray diffraction technique diffraction analyses at multiple incident angles yield residual stress magnitudes for the specified directions on the plane parallel to the sample surface residual stress formation in the vein is found to be determined by the platy geometry with respect to the host rock the results indicate a compressive residual stress of 15 to 20 mpa parallel to the long axis of the vein the compressive stress magnitude parallel to the quartz vein is found to increase with sample temperature indicating that the quartz vein has a greater thermal expansion coefficient than that of the host rock a two dimensional model explaining residual stress formation in the vein in response to tectonic exhumation is proposed and the paleostress magnitude at the time of vein formation is estimated from the residual stress magnitude and fluid inclusion microthermometric data the quartz vein is concluded to have formed under a horizontal compressive stress of 550 660 mpa in the direction parallel to the long axis of the vein

formation of deep incisions into tide dominated river deltas implications for the stratigraphy of the sego sandstone book cliffs utah u s a abstract the upper cretaceous sego member of the mancos shale in east central utah is composed of tidally deposited sandstones interbedded with intervals containing marine shales and thin wave deposited sandstones the tidal sandstones have been interpreted to comprise multiple amalgamated estuarine valley fills above a major sequence boundary that is incised into distal marine deposits of the underlying buck tongue shale according to this interpretation the deposits constitute the base of a thick transgressive succession within the sevier foreland clastic wedge alternatively lower sego sandstones have recently been interpreted by the authors to be tide dominated river delta deposits in an overall regressive interval of the foreland succession a cross section showing facies variations and stratigraphic surfaces within the lower sego member along 100 kilometers of the eastern book cliffs is used in this paper to refine depositional and sequence stratigraphic interpretations of these tidal deposits particularly the origin of deep incisions within the sego sandstones a strike oriented section of the lower sego member reveals tidal sandstone lenses 40 50 kilometers wide and tens of meters thick separated laterally by areas tens of kilometers wide that have no tidal sandstones facies variations within the tidal sandstones reflect depositional processes on tide dominated deltas that prograded obliquely into the shallow intracratonic western interior seaway of north america two major episodes of delta progradation and subsequent transgressions are interpreted to have formed tidal sandstone layers within the lower sego sandstone thinner tidal sandstone layers of more local extent are interpreted to reflect changes in tidal current strength but not necessarily shifts in shoreline position or major changes in water depth multiple origins are suggested for incised erosion surfaces within the lower sego sandstones firstly the tide dominated deltaic sandstones are floored by laterally discontinuous erosion surfaces these basal surfaces marking abrupt vertical changes in depositional process and coarsening of grain size are interpreted to record tidal scouring of the sea floor during shoreline progradation secondly sharp based upward coarsening deltaic sandstones are cut by numerous deep incisions with tens of meters of relief and locally they are entirely removed by erosion some of this deep erosion within the lower sego sandstone may reflect the upstream avulsion of incised distributaries during forced regression of deltas into the basin whereas others may have formed by tidal erosion of abandoned distributaries during more gradual progradation and subsequent retrogradation of deltas highly variable facies trends within incision fills are related to pronounced changes in sediment supply to different distributaries on the delta to differences between incisions cut during delta regression versus those cut during the start of transgression and to varying distances from delta axes when the entire coast was transgressed the influence of tides waned and wave generated currents ravined delta tops depositional interpretations of the sego member indicate that the buck tongue to neslen interval lies in a broadly regressive part of the foreland basin fill

sequence stratigraphy of a condensed low accommodation succession lower upper cretaceous dakota sandstone henry mountains southeastern utah cretaceous low accommodation deposits have been extensively studied in the subsurface of the western interior of north america because of their prolific hydrocarbon production and remaining potential understanding the stratigraphic complexities of these deposits in the subsurface relies strongly on detailed outcrop analogs in this study the dakota sandstone was examined along 100 km 62 mi of semicontinuous outcrop between the towns of hanksville and ticaboo in the henry mountains of southeastern utah this region represented a low accommodation setting located over the forebulge of the cretaceous western interior basin during accumulation of the unit the dakota sandstone is 0 to 38 m 125 ft thick of cenomanian age and records multiple cycles of sediment accumulation the dakota sandstone is subdivided into two condensed top truncated stratigraphic sequences the upper of which contains two parasequences the basal parts of both sequences are composed of braided fluvial conglomerates and sandstone overlain by tidally influenced fluvial sandstone inclined heterolithically stratified estuarine mudstone carbonaceous shale and coal the overlying parasequences consist of coarsening upward lower to upper shoreface mudstone sandstone tidal inlet deposits and oyster shell concentrations these facies define tripartite subdivisions of depositional environments typical of wave dominated estuaries the fluvial deposits may represent lowstand deposits but overall sediments accumulated during transgressive systems tracts tst the parasequences recorded in the henry mountains are similar to the dakota sandstone of northwestern new mexico and to high frequency sequences identified in the kaiparowits plateau approximately 80 km 50 mi to the southwest which suggests eustatic driving mechanisms the best potential for hydrocarbon reservoirs occurs in fluvial sandstones and conglomerates

late cretaceous subsidence in wyoming quantifying the dynamic component the late cretaceous western interior basin of north america is generally considered to have been a retroarc foreland basin flexural backstripping of the stratigraphic record from 97 2 ma to 73 4 ma along a section perpendicular to the wyoming idaho salient of the sevier belt clearly demonstrates that there were components of subsidence in addition to those driven by the thrust and associated sediment loads the simulation demonstrates that the flexural foredeep is only 180 120 km wide and shows a forebulge located near the subsequent laramide rock springs uplift foredeep strata between the rock springs uplift on the east and the thrust front to the west were mostly involved in the eastward overlapping thrust belt or deeply truncated by inferred rebound after 78 5 ma the difference between the observed decompacted cumulative subsidence and the amount of subsidence that can be explained by simple flexural loading the residual subsidence increases from 800 m in eastern wyoming to 1 8 km near the thrust belt the westward thickening upper cretaceous sediment wedge filled the accommodation space generated by downward tilting to the west of the north american cratonic margin by underplating and mantle flow associated with the shallowly subducted farallon plate

paleogeographic and paleotectonic setting of laramide sedimentary basins in the central rocky mountain region in the rocky mountain region between central montana and central new mexico sedimentologically isolated nonmarine basins were produced by basement deformation during the laramide orogeny within the area formerly occupied by a broad late cretaceous foreland basin in which laterally continuous marine facies had accumulated previously laramide structures of varying trend and scale reflect heterogeneity of crustal strain caused by shear between the continental lithosphere and an underlying subhorizontal slab of subducted oceanic lithosphere laramide basins include perimeter basins along the cratonic periphery of the arcuate laramide province axial basins along a north south intramontane trend and ponded basins located farther west closer to the overthrust belt twelve specific stratigraphic and sedimentologic criteria for the onset duration and termination of laramide deformation allow the chronology of basin development to be inferred independently for each basin maastrichtian initiation of laramide deformation was approximately synchronous throughout the laramide province but termination of laramide deformation was systematically diachronous from north to south between early and late eocene time widespread eocene erosion surfaces truncate syntectonic laramide sequences and are overlain by largely volcanic and volcaniclastic post laramide strata of eocene age in the north and oligocene age in the south fluvial depositional systems draining toward the great plains were dominant in perimeter and axial basins but ponded basins were occupied at times by large lakes that served as regional sediment traps paleocene drainages from ponded basins also led eastward toward the continental interior but partly interconnected lakes that developed within several ponded basins by mid eocene time were either closed hydrologically or else they drained westward into the tyee paleoriver of the pacific northwest

rethinking the incised valley fill paradigm for campanian book cliffs strata utah colorado u s a evidence for discrete parasequence scale shoreface incised channel fills

early cementation during marine meteoric fluid mixing mississippian lake valley formation new mexico abstract pre pennsylvanian low magnesium calcite cements from the mississippian lake valley formation of south central new mexico comprise three major cathodoluminescent zones previous work by meyers and lohmann 1985 suggested that interzonal isotopic and minor element variation resulted from spatial and temporal exchange between meteoric water and marine carbonate within a single meteoric system that the carbonate for cementation was derived from dissolution of metastable carbonate grains and that any contribution from marine water was insignificant isotopic analysis of the first two cathodoluminescent zones using detailed micron scale sampling methods revealed a record of simultaneous variation in 18o and 13c values at the intrazonal scale that is incompatible with compositional change anticipated from the evolution of meteoric fluids in response to progressive water rock interaction rather isotopic data in conjunction with stratigraphic and petrographic constraints suggest that regionally extensive mixing between marine and meteoric water along the basal margin of the phreatic lens is the process responsible for the cementation of much of this platform succession although trends of progressive 18o and 13c depletion in cement composition are compatible with precipitation from a fluid that evolved from a marine to a meteoric dominated composition low mg and sr concentrations are problematic in the context of experimentally derived partition coefficients for calcite because of compelling evidence indicating a mixing zone origin for these cements however we attribute low mg and sr contents to temperature and or pco2 effects or to differences in conditions under which calcite is precipitated

using neutron diffraction to investigate the elastic properties of anisotropic rocks results from an olivine orthopyroxene mylonite 1 the penetrating power of neutrons means that neutron diffraction may be employed to determine the lattice parameters of mineral phases within samples over 1 cm in size we have exploited this fact to obtain high resolution measurements of the elastic strains experienced by olivine and orthopyroxene during room temperature uniaxial deformation experiments performed in a neutron beam line on a mylonite from the oman ophiolite specimens were loaded in three orthogonal directions with respect to the macroscopic fabric of the rock in each case the average olivine and orthopyroxene strains were the same even though the elastic stiffnesses of the two phases were different in comparison with the strains expected from the single crystal elastic stiffness tensors the average strains in the different lattice directions for each phase were found to be greater in the stiffer directions and lesser in the more compliant directions the overall effect of this tendency toward strain homogenization was for the measured elastic anisotropy of the rock to be significantly lesser than that given by voigt reuss averaging of the single crystal elastic properties according to the lattice preferred orientations of each phase the technique used to derive these conclusions potentially provides an important experimental method for the quantitative examination of nonfracture related controls on the elastic anisotropy of geological materials

re evaluating the sedimentology and sequence stratigraphy of classic book cliffs outcrops at tusher and thompson canyons eastern utah usa applications to correlation modelling and prediction in similar nearshore terrestrial to shallow marine subsurface settings worldwide abstract the campanian book cliffs strata of eastern utah and western colorado has been used to develop test and refine sedimentological and stratigraphic ideas and models over the years including the principles and concepts of sequence stratigraphy book cliffs data sets are often used as outcrop analogues for similar subsurface settings worldwide thousands of geologists have visited the book cliffs including the archetypal desert member to lower castlegate sandstone outcrops at tusher and thompson canyons which are the focus of this study these localities regularly serve as representative field stops for teaching sequence stratigraphy recent work has begun to cast doubt on certain aspects of the conventional sequence stratigraphic interpretation of the desert castlegate interval hence re evaluation of these classic outcrops is warranted a progradational stack of shallow marine to nearshore terrestrial facies are observed at tusher canyon from bottom to top these include shelf mudstones lower shoreface to inner shelf heterolithics foreshore to upper shoreface sandstones cut by distributary and tidal estuarine channels coal bearing coastal plain mudstones with single storey fluvial sandstones amalgamated multi storey fluvial channel fills and a capping coastal plain mudstone package overlain by the marine mudstones of the buck tongue of the mancos shale a similar progradationally stacked facies succession is observed 30 km basinwards at thompson canyon with the exception of the proximal amalgamated fluvial sandstone package which is absent five of eleven desert member parasequences d1 to d5 are noted at tusher canyon while all eleven desert parasequences d1 to d11 and two of six castlegate parasequences c1 and c2 are identified at thompson canyon although parasequences and their flooding surfaces can be correlated between tusher and thompson canyons the discrete shoreface incised channels are only restricted to the proximal portions of each parasequence these channels mostly cut foreshore shoreface sandstones and are not continuously correlatable between tusher and thompson canyons re examination of these desert castlegate outcrops exemplifies the misfit with the conventional sequence stratigraphic model specifically the miscorrelation of the d5 and d11 shoreface incised channels over 60 m of deposits separate the d5 and d11 horizons along 30 km of dip oriented outcrop between tusher and thompson canyons contrary to earlier interpretations the shoreface incised channels in the desert castlegate are not nested within larger incised valley fills an alternative model showing temporal and spatial linkage between the nearshore terrestrial and laterally adjoining shallow marine facies is the best fit with the desert castlegate field observations selecting the appropriate correlation style has significant implications for the prediction of sand body continuity connectivity and distribution especially applications to subsurface data sets where visualization is limited and correlation uncertainties are high

sequential architecture in a fluvial succession sequence stratigraphy in the upper cretaceous mesaverde group prince canyon utah abstract five unconformity bounded sequences have been documented within a 1300 m thick succession of predominantly fluvial upper cretaceous and lower tertiary deposits in the price canyon area of the westernmost part of the book cliffs east central utah u s a this area experienced major tectonically induced changes in the paleogeography during deposition the earliest fluvial deposits in the study area were formed in a relatively simple foreland basin setting in front of the sevier orogenic belt and contain more marine influence than previously recorded following a gradual termination of thrusting sedimentation became increasingly controlled by uplift of the san rafael swell to the southeast our studies suggest that the fluvial systems in the upper part of the succession alternated bet een being confined within a valley open towards the north and being more directly eastward flowing on the basis of the observed sequences an idealized model of alluvial sequences whose internal architecture can be related to a fall rise fall cycle of the stratigraphic base level has been established upward or downward changes in the position of this base level dictate the creation and destruction of accommodation on the alluvial plain and therefore exert a direct control on the sequential architecture and sandstone body geometry of fluvial successions in our model the basal sequence boundary is overlain by an amalgamated fluvial sandstone sheet the sheet is succeeded by a fining upward more mudstone rich level with more isolated sandstone bodies and this level may culminate in a marine or lacustrine transgression the upper part of the sequence may show a coarsening upward trend heralding the next phase of base level fall and sequence boundary generation use of the suggested model has the potential to refine existing lithostratigraphic schemes and given the higher resolution and more detailed correlation may significantly improve paleogeographic reconstructions and aid in prediction of potentially hydrocarbon bearing reservoirs a revised and refined lithostratigraphy has been established on the basis of alluvial sequence analysis the lower half of the succession forms the youngest part of a major eastward prograding clastic tongue the mesaverde group and is campanian we divide this part into the blackhawk castlegate and price river formations the rest of the succession is maastrichtian to paleocene and is referred to the north horn formation this formation was deposited in an intermontane setting

viscoplastic self consistent and equilibrium based modeling of olivine lattice preferred orientations implications for the upper mantle seismic anisotropy anisotropy of upper mantle physical properties results from lattice preferred orientation lpo of upper mantle minerals in particular olivine we use an anisotropic viscoplastic self consistent vpsc and an equilibrium based model to simulate the development of olivine lpo and hence of seismic anisotropy during deformation comparison of model predictions with olivine lpo of naturally and experimentally deformed peridotites shows that the best fit is obtained for vpsc models with relaxed strain compatibility slight differences between modeled and measured lpo may be ascribed to activation of dynamic recrystallization during experimental and natural deformation in simple shear for instance experimental results suggest that dynamic re crystallization results in further reorientation of the lpo leading to parallelism between the main 010 100 slip system and the macroscopic shear thus modeled simple shear lpos are slightly misoriented relative to lpos measured in natural and experimentally sheared peridotites this misorientation is higher for equilibrium based models yet seismic properties calculated using lpo simulated using either anisotropic vpsc or equilibrium based models are similar to those of naturally deformed peridotites errors in the prediction of the polarization direction of the fast s wave and of the fast propagation direction for p waves are usually 15 moreover overestimation of lpo intensities in equilibrium based and vpsc simulations at high strains does not affect seismic anisotropy estimates because these latter are weakly dependent on the lpo intensity once a distinct lpo pattern has been developed thus both methods yield good predictions of development of upper mantle seismic anisotropy in response to plastic flow two notes of caution have nevertheless to be observed in using these results 1 the dilution effect of other upper mantle mineral phases in particular enstatite has to be taken into account in quantitative predictions of upper mantle seismic anisotropy and 2 lpo patterns from a few naturally deformed peridotites cannot be reproduced in simulations these abnormal lpos represent a small percent of the measured natural lpos but the present sampling may not be representative of their abundance in the earth s upper mantle

the geometry and internal architecture of stream mouth bars in the panther tongue and the ferron sandstone members utah u s a abstract clinothems are seaward dipping beds which are deposited during the progradation of delta front mouth bars measurements taken from clinothems in the field and from geospatially constrained photo realistic virtual outcrops were used to record clinothem dip maximum bed thickness and bed thickness every 10 m along a series of depositional dip oriented profiles from two ancient river dominated delta successions which crop out in central utah usa these data show systematic changes in bed dip and bed thinning which highlight discrete packaging of the beds into bedsets interpreted to represent the progradation of stream mouth bars in the delta front individual bedsets are characterized by a progressive steepening of beds coupled with a more rapid thinning systematic collection of 2800 locations along 73 separate clinothems from the panther tongue sandstone member and parasequence 1f from the ferron sandstone were used to study the relationship between bed thickness dip and decay gradient parameter which describes the down dip bed thinning clinothems in the panther tongue are much longer and more gently dipping than the clinothems in the ferron sandstone in both systems beds can be clustered into groups bedsets which show a systematic decrease in values and an increase in dip angle boundaries between the groups are defined by a sudden increase in values and a concurrent decrease in dip angle these bedsets are interpreted to represent individual stream mouth bars which amalgamate to form mouth bar complexes within the delta front sand bodies the use of virtual outcrops was essential for the collection of the large volumes of thickness data and the recognition of very subtle 1 changes in dip angle which have made these interpretations possible

the castlegate sandstone of the book cliffs utah sequence stratigraphy paleogeography and tectonic controls abstract earlier stratigraphic work had predicted that at the type section of the castlegate formation the castle gate near price utah the unit consists of two sequences separated by a sequence boundary representing approximately one million years of unrecorded time although the type section is well exposed it consists of a monotonous succession of braided fluvial sandstones and no obvious boundary can be identified using facies criteria this is a good example of a cryptic sequence boundary petrographic data indicate however a significant change in detrital composition 20 m above the base of the section at a through going erosion surface that is therefore interpreted as the sequence boundary revised sequence correlations together with other petrographic data and regional paleocurrent patterns provide the basis for a model of the paleogeographic evolution of the area rocks assigned to the castlegate sandstone comprise two or possibly three sequences formed at times of slow regional subsidence erosional sequence boundaries and tilts in paleoslope between each sequence record thrust loading and unloading of the basin and the growing influence of intrabasinal upwarps movement of which was beginning to be affected by laramide movements toward the end of castlegate sedimentation

high resolution sequence stratigraphic correlation between shallow marine and terrestrial strata examples from the sunnyside member of the cretaceous blackhawk formation book cliffs eastern utah the sunnyside member of the upper cretaceous blackhawk formation in the book cliffs of eastern utah provides an ideal opportunity to investigate high resolution sequence stratigraphic correlation between shallow marine and terrestrial strata in an area of outstanding outcrop exposure the thick laterally extensive coal seam that caps the sunnyside member is critical for correlating between its shallow marine and terrestrial components petrographic analysis of 281 samples obtained from 7 vertical sections spanning more than 30 km 18 mi of depositional dip enabled us to recognize a series of transgressive regressive coal facies trends in the seam on this basis we were able to identify a high resolution record of accommodation change throughout the deposition of the coal as well as a series of key sequence stratigraphic surfaces the stratigraphic relationships between the coal and the siliciclastic components of the sunnyside member enable us to correlate this record with that identified in the time equivalent shallow marine strata and to demonstrate that the coal spans the formation of two marine parasequences and two high frequency fourth order sequence boundaries this study has important implications for improving the understanding of sequence stratigraphic expression in terrestrial strata and for correlating between marine and terrestrial records of base level change it may also have implications for improving the predictability of vertical and lateral variations in coal composition for mining and coalbed methane projects

strain investigations on calcite marbles using neutron time of flight diffraction in order to describe and explain the effect of bowing of marble facade panels neutron time of flight diffraction was applied to determine residual macro and microstrain on the calcite mineral phase the measurements were combined with investigations of the crystallographic preferred orientation texture measurements by neutron diffraction macroscopic measuring of the bowing on marble building stones as well as microfabric analyses three samples were investigated to explain the bowing effect a fresh broken sample a good conditioned facade panel and a strongly deformed facade panel residual intracrystalline strain was detected in all investigated samples which differed in the degree of bowing for the first time the preferred orientation and the residual strain were found to be related the results show that different strain magnitudes are reflected by residual strains which differ significantly in magnitude and direction furthermore different bragg peak widths have been detected as an indication of microscopic strain the observed residual strain values in the samples are related with the grain shape and texture properties

using neutron diffraction to examine the onset of mechanical twinning in calcite rocks experimental calibration of the calcite twin piezometer is complicated by the difficulty of establishing the stresses at which the twins observed in the final deformation microstructures actually formed in principle this difficulty may be circumvented if the deformation experiments are performed in a polychromatic neutron beam line because this allows the elastic strain and hence stress in differently oriented grains to be simultaneously monitored from diffraction patterns collected as the experiment is proceeding to test this idea small strain 0 3 uniaxial compression experiments have been performed on carrara marble grain size 150 m and solnhofen limestone 5 m at temperatures of 20 600 c using the engin x instrument at the isis neutron facility uk at the lowest temperatures 25 c carrara 200 c solnhofen the deformation response was purely elastic up to the greatest stresses applied 60 mpa carrara 175 mpa solnhofen the sign of the calcite elastic stiffness component c14 is confirmed to be positive when the obverse setting of the calcite rhombohedral lattice in hexagonal axes is used in the carrara marble samples deformed at higher temperatures elastic twinning was initiated at small stresses 15 mpa in grains oriented such that the schmid factor for twinning was positive on more than one e twin system at greater stresses 65 mpa at 200 c decreasing to 41 mpa at 500 c there was an abrupt onset of permanent twinning in grains with large schmid factors for twinning on any one e twin system no twinning was observed in the solnhofen limestone samples deformed at 200 or 400 c at applied stresses of 180 mpa these results highlight the potential of this approach for detecting the onset of twinning and provide through experiments on samples with different microstructures a strategy for systematically investigating the effects of microstructural variables on crystallographically controlled inelastic processes

architecture and origin of an amalgamated fluvial sheet sand lower castlegate formation book cliffs utah abstract amalgamated fluvial sheet sandstones in the stratigraphic record are often interpreted as the deposits of braided rivers alluvial sequence stratigraphic models show these sheet sandstones overlying sequence boundaries and deposited during low rates of base level rise and fall since sequence stratigraphic models rely on the balance between creation destruction of accommodation and sediment supply is the sheet like nature of these units controlled by channel style by aggradation rates tied to base level changes or a combination of both the lower member of the castlegate formation in the book cliffs of eastern utah u s a was selected to answer these questions regarding the origin and architecture of amalgamated sheet sandstones the lower castlegate is 60 m thick and is underlain by a regional sequence boundary delineation of the alluvial architecture utilized a combination of outcrop photography measured sections and paleochannel dimension estimation at two outcrops in the type area architectural components within the outcrops were defined and include 1 basal thalweg fill units 2 inclined sandy or heterolithic barform deposits and 3 overbank siltstone and mudstone thalweg fill units represent deposition in the topographically lowest part of the channel and are preferentially preserved thalweg units exist as single units or as a composite of multiple thalweg units overlying thalweg units inclined barform deposits are in places preserved and genetically linked to an underlying thalweg fill unit bar accretion directions when combined with paleocurrent indicators show that lateral downstream and upstream accretion all occur in the lower castlegate overbank deposits are rarely preserved but where present they typically overlie bar deposits the architectural components stack to form a threefold cyclic hierarchy of 1 channel bar systems 2 12 m thick 2 channel belts 2 16 m thick and 3 stacked channel belt complexes 17 40 m thick complete channel bar systems are rarely preserved and occur locally as a succession of multiple stacked thalweg fill units the lack of barforms within a composite thalweg unit suggests that channel migration is the dominant process controlling preservation within channel bar systems possibly associated with a component of local avulsion channel belts are composed of stacked channel bar systems capped by a barform the barform is preserved due to a regional avulsion moving the active channel to another location within the floodplain isolating it from potential reworking stacked channel belt complexes are characterized by alternations of thalweg dominated and barform dominated channel belts the mechanism responsible for deposition at the stacked channel belt complex scale may be creation destruction of accommodation associated with base level changes paleochannel reconstructions show that channel flow depths using bar and underlying thalweg thickness were up to 7 6 m channel depth estimates utilizing a cross bed set thickness of 26 cm averaged 4 6 7 7 m these values were used to calculate channel widths which were estimated at 143 365 m up to a maximum of approximately 1 km regional paleoflow within the lower castlegate was dominantly southeast directed the architectural components paleochannel characteristics and paleocurrent data suggest the lower castlegate member was deposited in low to intermediate sinuosity rivers influenced by autocyclic processes at smaller scales and allocyclic processes at the larger outcrop scale

high frequency late pliocene marine cyclothems from wanganui basin new zealand a model for high resolution sequence stratigraphic analysis of shelf sequences at the outcrop abstract

a sedimentological and sequence stratigraphic reinterpretation of the upper cretaceous prairie canyon member mancos b and associated strata book cliffs area utah usa the mancos shale book cliffs eastern utah usa represents the open marine mudstones of the cretaceous western interior seaway and encloses the prairie canyon member which is located over 50 km seaward of interpreted contemporaneous highstand shoreline deposits in the blackhawk formation examination of the member reveals that it does not wholly represent offshore deposition as previously interpreted but instead contains three nearshore facies associations 1 tidally influenced fluvial channel fills 2 fluvial dominated delta fronts and 3 weakly storm influenced shorefaces tidally influenced fluvial channel fills are commonly stacked into multistory bodies that can be traced for tens of kilometers at discrete stratigraphic levels defining incised valley fill networks four such incised valley networks are identified at outcrop fluvial dominated deltas and weakly storm influenced shorefaces are eroded into by and lie at the down dip terminations of incised valley fills and are interpreted as forced regressive and lowstand shoreface deposits one incised valley fill appears to be onlapped by additional fluvial dominated deltas which represent pulses of shoreface progradation during an overall transgression forced regressive lowstand and transgressive shorefaces in the prairie canyon member differ significantly from highstand shorefaces in the blackhawk formation the former are sand poor and weakly wave storm influenced whereas the latter are sand rich and wave dominated this change in shoreface style reflects increased mud supply and an enhanced embayment paleogeography during periods of relative lowering of sea level

use of spectral gamma ray data to refine subsurface fluvial stratigraphy late cretaceous strata in the book cliffs utah usa high resolution sub seismic stratigraphic correlation in fluvial strata is extremely difficult using conventional subsurface core and wireline log data e g gamma ray neutron density sonic logs spectral gamma ray logs provide additional data on lithological composition that can aid identification of chronostratigraphic surfaces in a high resolution sequence stratigraphic correlation framework the application of spectral gamma ray data in constructing such a framework is demonstrated using data from exposures and the subsurface from the cretaceous non marine blackhawk formation and castlegate sandstone of the book cliffs area utah usa these strata provide an ideal test case for the use of spectral gamma ray data in fluvial stratigraphy because interpretations can be compared directly with a high resolution sequence stratigraphic framework from coeval shallow marine strata exposed nearby the stratigraphic abundance of coals and relatively uniform th k ratio which indicates uniform clay mineralogy in mudstone sections of the non marine blackhawk formation implies a humid subtropical climate throughout its deposition variations in facies architecture and stratigraphy are therefore interpreted to have been driven principally by fluctuations in relative sea level and hinterland tectonics fluvial and fluvio tidal sandstones within incised valleys which lie above erosional sequence boundaries have a highly variable spectral gamma ray character but locally are marked by distinctive heavy mineral lags and concentrations th consistently 3 ppm on the interfluves of incised valleys sequence boundaries are marked by palaeosols that locally have a distinctive leached potassium depleted character th k ratio 17 lateral variability in spectral gamma ray character of sequence boundaries is consistent with facies and sequence stratigraphic models of the non marine blackhawk formation and castlegate sandstone but sequence boundaries do not exhibit a clear diagnostic character in every location in addition high th k ratios of the type noted at interfluve palaeosols may be produced by potassium depletion beneath coal seams as a result of acid groundwater percolation during early diagenesis and by thorium enrichment in heavy mineral lags within foreshore sandstones these alternative interpretations can be eliminated if high th k ratios occur in intervals lacking coal seams and shallow marine sandstones respectively thus within the context of a sound understanding of detrital mineralogy diagenetic history facies and appropriate sequence stratigraphic models spectral gamma ray data allow sequence boundaries to be identified and correlated in non marine fluvial strata at least 80 km from the interpreted coeval shoreline

two models global sea level change and sequence stratigraphic architecture abstract two different conceptual models underlie the application of sequence stratigraphy by exxon stratigraphers and later researchers one the global sea level model gsm relates to presumed sea level behaviour through time the other the sequence stratigraphic model ssm relates to the stratigraphic record produced during a single cycle of sea level change though the two models are inter related they are logically distinct and it is important to test them separately a summary is presented of the nature of the two models and of the nomenclature that is used in their description it is concluded a that the global sea level model comprises an assembly of local relative sea level events which are widely recognisable within their parent sedimentary basin and b that the sequence stratigraphic model is robust and its application is therefore an insightful way to approach the interpretation of sedimentary rocks

intra parasequence architecture of an interpreted asymmetrical wave dominated delta although modern wave dominated shorelines exhibit complex geomorphologies their ancient counterparts are typically described in terms of shoreface shelf parasequences with a simple internal architecture this discrepancy can lead to poor discrimination between and incorrect identification of different types of wave dominated shoreline in the stratigraphic record documented in this paper are the variability in facies characteristics high resolution stratigraphic architecture and interpreted palaeo geomorphology within a single parasequence that is interpreted to record the advance of an ancient asymmetrical wave dominated delta the standardville ab1 parasequence of the aberdeen member blackhawk formation is exposed in the book cliffs of central utah usa this parasequence and four others in the aberdeen member record the eastward progradation of north south trending wave dominated shorelines within the standardville ab1 parasequence distal wave dominated shoreface shelf deposits in the eastern part of the study area are overlain across a downlap surface by southward prograding fluvial dominated delta front deposits which have previously been assigned to a separate stranded lowstand parasequence formed by a significant allogenic change in relative sea level high resolution stratigraphic analysis of these deposits reveals that they are instead more likely to record a single episode of shoreline progradation characterized by alternating periods of normal regressive and forced regressive shoreline trajectory because of minor cyclical fluctuations in relative sea level interpreted normal regressive shoreline trajectories within the wave dominated shoreface shelf deposits are marked by aggradational stacking of bedsets bounded by non depositional discontinuity surfaces interpreted forced regressive shoreline trajectories in the same deposits are characterized by shallow incision of fluvial distributary channels and strongly progradational stacking of bedsets bounded by erosional discontinuity surfaces that record enhanced wave base scour fluvial dominated delta front deposits most probably record the regression of a lobate delta parallel to the regional shoreline into an embayment that was sheltered from wave influence wave dominated shoreface shelf and fluvial dominated delta front deposits occur within the same parasequence and their interpretation as the respective updrift and downdrift flanks of a single asymmetrical wave dominated delta that periodically shifted its position provides the most straightforward explanation of the distribution and relative orientation of these two deposit types

no evidence for an unconformity at the base of the lower castlegate sandstone in the campanian book cliffs utah colorado united states implications for sequence stratigraphic models regional high resolution correlations of the campanian desert member of the blackhawk formation to the lower castlegate sandstone interval book cliffs utah colorado show no evidence for a single through going unconformity separating the amalgamated channel sandstones of the castlegate from the underlying blackhawk formation coastal plain deposits this is a facies contact which interfingers both laterally and vertically channel incisions are discrete and mostly confined to individual parasequences they do not coalesce landwards into gigantic valleys as shown in the conventional model but are restricted to the proximal shoreface and are rarely traceable for more than a few kilometers landwards time lines extend uninterupted from the shallow marine into the neighbouring coastal plain deposits connecting flooding surfaces with coals shoreface sandstones emerge from the adjacent coastal plain this has significant implications for modelling in similar clastic settings worldwide conventional sequence stratigraphic models of fluviodeltaic systems show radically different stacking patterns compared to those of the high resolution model presented herein each model carries a significantly different prediction regarding the three dimensional distribution and architecture of reservoir and nonreservoir bodies in a fluviodeltaic system hydrocarbon exploration and development activities such as optimally locating seismic surveys and or drilling locations could be impacted if the wrong model is applied as such it is recommended that fluviodeltaic systems worldwide should be critically re examined in the light of the high resolution sequence stratigraphic model presented herein

a determination of the three dimensional seismic properties of anorthosite comparison between values calculated from the petrofabric and direct laboratory measurements bernard eront and david mainprice zaboratoire de tectonophysique i h iversit montpe lier ii montpe lier france nikolas i christensen department of earth and atmospheric sciences purdue unh ersity west lafayette btdiana we have undertaken a coinparative study of the seisnfic properties of an anorthosite the seisnfic properties have been calculated froin the lattice preferred orientation lpo of plagioclase 90 by volume and olivine 10 by voluine and the elastic constants of these minerals laboratory measurements of vp 24 directions and vs 6 directions have been made on the same sample at room temperature and pressures up to 1 0 gpa the twe techniques agree with 0 1 km s for all orientations studied when the voigt averaging method is used hill and reuss averaging methods give calculated velocities significantly lower than the experimental ones a study of the difference between the velocity values given by the two methods reveals a systematically larger departure in orientations normal to the foliation the orientation dependent difference between the two tedmiques can be explained if there are small errors in the elastic constants for single crystal plagioclase used in the initial calculations the axial lpo symmetry of the plagioclase with all the crystallographic b axes parallel to the specimen symmetry axis allowed us to calculate c22 norinal to 010 directly from the laboratory measurement of vp some constraints can be put on c22 c44 c66 c12 and c23 on average our data require 10 modification of the single crystal constants reported by ryzhova 1964

shoreface tongue geometry constrains history of relative sea level fall examples from late cretaceous strata in the book cliffs area utah progradational shoreface tongues preserve a near complete depositional record of relative sea level highstands falls and lowstands two distinct styles of progradational shoreface tongue are examined in an extensive outcrop and subsurface dataset from late cretaceous strata of the book cliffs area utah representing i highstand through attached lowstand progradation and ii highstand through detached lowstand progradation using this dataset key geometrical attributes of the shoreface tongues and their internal facies architecture are identified and quantified that enable the reconstruction of relative sea level fall history for example attached wave dominated lowstand shoreface deposits record a slow 0 2 0 3 mm yr 1 low magnitude 14 m relative sea level fall punctuated by minor rises detached weakly wave influenced lowstand shoreface deposits record a more rapid 0 4 0 5 mm yr 1 high magnitude 45 m relative sea level fall synchronous with a marked change in sediment delivery and depositional process regime at the shoreline

monitoring in situ stress strain behaviour during plastic yielding in polymineralic rocks using neutron diffraction abstract attempts to use rock deformation experiments to examine the elastic and plastic behaviour of polymineralic rocks are hampered by the fact that usually only whole sample properties can be monitored as opposed to the separate contribution of each phase to circumvent this difficulty room temperature uniaxial compression experiments were performed in a neutron beam line on a suite of calcite halite samples with different phase volume proportions by collecting diffraction data during loading the elastic strain and hence stress in each phase was determined as a function of load to bulk strains of 1 2 in all cases the calcite behaved elastically while the halite underwent plastic yielding during the fully elastic part of the deformation the composite elastic properties and the within phase stresses are well described both by recent shear lag models and by analyses based on eshelby s solution for the elastic field around an ellipsoidal inclusion in a homogeneous medium after the onset of yielding the halite in situ stress total strain curve may be reconstructed using the rule of mixtures at calcite contents of greater than 30 the in situ halite response may be significantly weaker or stronger than that obtained at lesser calcite contents the results highlight the potential that such techniques offer for developing an explicitly experimental approach for determining the influence of microstructural variables on the mechanical properties of polymineralic rocks

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

perspectives on the sequence stratigraphy of continental strata this report is the result of a working group on continental sequence stratigraphy that was set up at the 1991 nuna conference in banff canada to date sequence stratigraphic concepts have been applied mainly to the marine realm but unconformity bounded units have long been recognized in nonmarine strata successful application of sequence stratigraphic concepts to continental strata requires careful consideration of controls on base level and sediment supply as with shallow marine environments relative sea level can be considered as the stratigraphic as well as the geomorphic base level for coastal nonmarine settings farther inland stratigraphic base level which determines accommodation space is more complex and takes various forms such as the graded profile for fluvial strata groundwater tables for some eolian strata and lake level for some intermontane sediments sediment supply is also generally a more complex variable for nonmarine environments than in the marine realm because of the proximity to the source area the influence of climate and tectonism on sediment supply can clearly be seen in many continental sediments the fact that the major controls of climate tectonism and eustasy are somewhat interdependent and that a change in one parameter will most likely be reflected in others is also more readily apparent in continental strata although in its infancy sequence stratigraphic concepts have been applied to a wide variety of continental settings in attempts to explain variations in facies architecture of particular interest are studies that have linked fluvial architecture on coastal plains to variations in relative sea level as indicated by coeval marine strata and studies of lacustrine environments that show marked variation in facies between highstand and lowstand deposits the application of sequence stratigraphy to continental strata will likely result in the development of better correlation techniques and models that better predict the location and nature of fluvial and eolian reservoirs

evidence of across shelf transport of fine grained sediments turbidite filled shelf channels in the campanian aberdeen member book cliffs utah usa the shore normal transport of fine grained sediments by shelf turbidity currents has been the focus of intense debate over the last 20 years many have argued that turbidity currents are unlikely to be a major depositional agent on the shelf however sedimentological architectural stratigraphic and palaeogeographic data from the campanian aberdeen member book cliffs eastern utah suggests otherwise and clearly demonstrates that storm generated and river flood generated underflows can transport a significant volume of fine grained sediments across the shelf these across shelf flowing turbidity currents cut large subaqueous channel complexes up to 7 m deep tens of kilometres basinward of their time equivalent shoreface the shelf channels were filled with organic rich siltstones mudstones and very fine to fine grained bouma like sandstone beds including wave modified turbidites hyperpycnites and classical turbidites deposition was above storm wave base palaeocurrent data reveal an overwhelmingly dominant across shelf east south east offshore directed transport trend tectonic activity and or concomitant palaeogeographic reorganization of the basin may favour the generation of these turbidite rich shelf deposits by altering the relative balance of wave versus fluvial energy increased erosion and sediment supply rates because of tectonic uplift of the hinterland may have increased the probability of fluvial dominance along the coastline and hence the possibility of submarine channelization in front of the river mouths additionally the coastline may have become more sheltered from direct wave energy thus allowing the fluvial processes to dominate seasonal increases in rainfall and storm activity may also favour the generation of across shelf underflows on wave dominated shorelines isolated shelf channels and lobes are most likely to be found down dip of fluvial feeder systems in relatively high sediment supply settings these features are also most likely to occur in systems tracts that straddle a sequence boundary especially those which are tectonically generated as these would enhance the potential for altering basin morphology and hence the balance of fluvial and wave energy isolated shelf channels are recognized in older and younger strata in the book cliffs region implying that wave supported gravity flows were a recurrent phenomena in the campanian of utah it is probable that isolated shelf bodies are preserved in other stratigraphic intervals in the cretaceous western interior of north america and other basins worldwide and are currently being overlooked or misidentified shoreface to shelf facies models should be revised to incorporate turbidite rich shelf deposits in some shelf settings

sequence concepts at seismic and outcrop scale the distinction between physical and conceptual stratigraphic surfaces abstract the sequence stratigraphic terms maximum flooding surface and downlap surface as currently applied are ambiguous examples of these intra sequence surfaces are summarised from high frequency mid pleistocene sequences and from a cretaceous recent seismic megasequence both from new zealand at any one locality a mid pleistocene sequence contains up to four stratal discontinuities in ascending order the sequence boundary ravinement surface local flooding surface and downlap surface these physical surfaces which occur in outcrop are regionally diachronous and should be differentiated from theoretical isochronous horizons such as the time of maximum flooding horizon corresponding to maximum shoreline transgression and the time of peak eustatic or local relative sea level horizons corresponding to the highpoint of the eustatic and relative sea level cycles respectively in seismic studies the boundary between the transgressive and highstand systems tracts is usually located at the downlap surface on the basis of a major thermo tectonic sea level cycle in the canterbury basin it is shown that the downlap surface is not a single regional surface and that the change in slope associated with toes of successive prograding clinoforms rises in stratigraphic height basinwards the downlap surface therefore does not usually coincide with the maximum flooding horizon in plio pleistocene cyclothems a discrete unit the mid cycle shellbed straddles the contact between the transgressive and highstand systems tracts this unit might be classified within its own systems tract the condensed section systems tract csst alternatively the position of the boundary between the transgressive and highstand systems tracts can remain unspecified or unknowable

high resolution correlation of the upper cretaceous stratigraphy between the book cliffs and the western henry mountains syncline utah u s a abstract exposures of upper cretaceous strata in the book cliffs have played a key role in the formulation of modern sequence stratigraphic concepts and yet correlations with time equivalent strata in nearby regions remain uncertain resulting in an incomplete understanding of regional paleogeography this study presents detailed high resolution correlations of the upper cretaceous stratigraphy between the book cliffs the wasatch plateau and the western henry mountains syncline in utah with emphasis on the campanian interval two newly acquired measured vertical sections at coal canyon near green river in the book cliffs and blind trail in the henry mountains inform the correlations which also incorporate the substantial body of previous research correlations are further constrained by vertical and lateral facies stacking patterns and changes in sediment dispersal directions at discrete stratigraphic horizons derived from paleocurrent measurements much of the campanian succession can be characterized as a single low frequency third order depositional sequence within which are nested numerous high frequency sequences while it is not possible to correlate every high frequency sequence recognized in individual outcrop areas we define four intervals numbered 1 4 in ascending stratigraphic order that we correlate across the entire region interval 1 basal campanian is represented by initially deltaic and later wave dominated shoreface strata of the star point sandstone and equivalent basal muley canyon sandstone interval 2 lower campanian comprises coastal plain facies passing eastward into shallow marine strata of the lower blackhawk formation and equivalent muley canyon sandstone interval 3 lower to mid middle campanian comprises a thick aggradational stack of coastal plain fluvial strata that pass eastward into coastal and shallow marine facies blackhawk formation and equivalent masuk formation interval 4 overlying a major facies dislocation third order sequence boundary comprises amalgamated sheet fluvial deposits of the lower castlegate sandstone and equivalent tarantula mesa sandstone during the early to middle campanian the northern wasatch plateau and western henry mountains regions were along depositional strike with respect to one another the book cliffs near green river were located obliquely down depositional dip from the western henry mountains region during the campanian these new correlations and the improved understanding of paleogeography that derive from them have the potential to inform basin scale stratigraphic interpretations to a greater extent than has been hitherto possible

fourth order nonmarine to marine sequences middle castlegate formation book cliffs utah the lower part of the campanian castlegate formation one of the best known fluvial sheet sands of the western interior seaway combines with an overlying finer grained unit middle member of the castlegate formation to form an unconformity bounded third order stratigraphic sequence 3 m y duration this sequence contains a mappable muddy zone along the western book cliffs of utah now mapped as contiguous with the open marine parts of the succession buck tongue sego sandstone anchor mine tongue to the east the correlation within the middle castlegate has been refined and the nature of the link between tidally influenced fluvial strata in the west and marine strata in the east has been remapped five high frequency stratigraphic sequences all within the upper part of the larger third order sequence forming a thickness to 160 m have been mapped in the price area southeastward into the time equivalent marine succession near green river individual sequences probably 0 5 m y duration reflecting transgressive to regressive estuary infilling have an internal architecture in which fluvial and tidally influenced distributary channel belts pass up into muddy central basin sedimentary units to bayhead delta deposits and in some places up to more fluvial channel belts the key to the mapping of individual sequences is recognition of the muddy brackish water interval developed during maximum transgression of the time equivalent shoreline the two most proximal marine influenced sequences 2 and 3 are probably broadly time equivalent with the buck and anchor mine tongues to the east the analysis here contrary to recent suggestions shows that the marine sequences in the eastern book cliffs can be traced far into the time equivalent western fluvio estuarine succession

lattice strain measurements on sandstones under load using neutron diffraction abstract neutron diffraction methods both time of flight and angle dispersive diffraction are applied to intracrystalline strain measurements on geological samples undergoing uniaxial increasing compressional load the experiments were carried out on cretaceous sandstones from the elbezone east germany consisting of 95 quartz which are bedded but without crystallographic preferred orientation of quartz from the stress strain relation the young s modulus for our quartz sample was determined to be 72 2 2 9 gpa using results of the neutron time of flight method the influence of different kinds of bedding in sandstones laminated and convolute bedding could be determined we observed differences of factor 2 convolute bedding and 3 laminated bedding for the elastic stiffness determined with angle dispersive neutron diffraction crystallographic strain and with strain gauges mechanical strain the data indicate which geological conditions may influence the stress strain behaviour of geological materials the influence of bedding on the stress strain behaviour of a laminated bedded sandstone was indicated by direct residual stress measurements using neutron time of flight diffraction the measurements were carried out six days after unloading the sample residual strain was measured for three positions from the centre to the periphery and within two radial directions of the cylinder we observed that residual strain changes from extension to compression in a different manner for two perpendicular directions of the bedding plane