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

geomagnetic intensity variation during the last 4000 years abstract thellier type determinations of the ancient geomagnetic intensity are reported for a large number of samples from greece comprising ancient pottery and other archaeologically dated forms of baked clay comparison is made with results for other parts of the world of about the same latitude the near east china and the western u s a these data indicate that in the time range studied variation of the geomagnetic dipole moment is unlikely to have been the dominant influence it is suggested that the westward drift of a non dipole disturbance could have been responsible

intensity of the geomagnetic field in western europe over the past 2000 years new data from ancient french pottery 1 we studied 14 groups of french pottery fragments dated between the 4th and 16th centuries the potsherds were analyzed using the thellier and thellier 1959 method revised by coe 1967 intensity values were corrected for thermoremanent magnetization trm anisotropy and cooling rate dependence of trm acquisition we first analyzed modern ceramics produced following ancient techniques and fired in a wood burning kiln inside of which field intensity was measured the recovered mean intensity is within 3 of the expected value which proves the reliability of our experimental procedure thermal experiments carried out at rapid and slow cooling rates clearly indicate that the cooling rate correction is critical in archeointensity studies our data indicate that large variations in intensity occurred in france over the last 2000 years two relative maxima in intensity are observed one between the 8th and 10th centuries and the second between the 14th and 15th centuries similarities are observed between the archeointensity data from france and ukraine yielding some evidence for eastward drift of geomagnetic sources between western and eastern europe from a d 800 to a d 1700 we also show that the dipole moment evolution proposed by mcelhinny and senanayake 1982 and yang et al 2000 for the last two millennia is likely biased toward higher values mainly because of the absence of correction for the cooling rate dependence of trm acquisition in most published archeointensity studies we finally underline a possible relationship valid at least in western europe between changes in direction and intensity of the geomagnetic field

vertical sequence and lateral transitions in the facies of a barred nearshore environment abstract nine tube cores 7 cm in diameter and up to 150 cm long from a nearshore crescentic bar in kouchibouguac bay new brunswick canada reveal the vertical sequence and lateral transitions of facies previously identified only in shallow box cores the facies are a inner shelf shoreface transition bioturbated fine sands and silts with remnant primary structures b seaward slope planar lamination in medium to fine sands dipping gently seaward and composite bed sets of planar to ripple cross lamination in fine sand chevron lamination is rare c bar crest low angle planar lamination dipping both landward and seaward and medium scale trough cross lamination in medium to coarse sands d landward slope planar lamination dipping landward with small scale la dward dipping trough cross lamination occasionally small to medium scale trough cross lamination is found with seaward dips e trough massively bedded lags of coarse gravelly sands with abundant shell fragments contrast with isolated very thin units of massive silt and units of well sorted sands the latter display subhorizontal planar lamination and small to medium scale trough cross lamination polymodal dips indicate bed form migration landward alongshore and offshore vertical sequences and lateral transitions seaward of the bar crest suggest that three wedge shaped units inner shelf shoreface transition seaward slope bar crest interdigitate in an offlap onlap sequence to landward the trough and landward slope facies interfinger complexly while the crest facies forms a simple onlap over landward slope facies total reworking of sediments within the bar trough system is expected every 5 to 6 years and long term preservation is limited to the inner shelf shoreface transition seaward slope and trough facies

early holocene regressive spit platform and nearshore sedimentation on a glaciofluvial complex during the yoldia sea and the ancylus lake phases of the baltic basin sw finland abstract the depositional history of the virttaankangas plain a fan like enlargement of the large sakylanharju glaciofluvial ridge in sw finland is examined the sakylanharju ridge has been interpreted as having formed as an interlobate esker and the morphology of the virttaankangas plain as representing predominantly subaqueous glaciofluvial to glaciolacustrine deposition this investigation uses new sedimentologic outcrop data with extensive subsurface drilling gpr surveys seismic soundings and gravimetric measurement data provided by groundwater investigations to describe the stratigraphy morphology and depositional history of the plain in contrast to earlier interpretations the results emphasise the role of littoral processes in the origin of the virttaankangas plain the plain is interpreted as having originated during the development of a progradational sequence of spit platform and superimposed nearshore sediments deposited during the glacio isostatic forced regression of the yoldia sea and ancylus lake phases of the baltic basin 9900 9000 14 c bp documented depositional history supports an interval of retarded regression at the beginning of the ancylus lake phase i 9500 9200 14 c bp in the sakylanharju area

archeointensities in greece during the neolithic period new insights into material selection and secular variation curve numerous archeomagnetic studies have provided high quality data for both the direction and the intensity of the geomagnetic field essentially in europe for the last 10 millennia in particular greece supplies a lot of archeological materials due to its impressive cultural heritage and volcanic activity so that numerous data have been obtained from burnt clays or historical lava flows the most recent greek secular variation curves are available for the last 8 millennia for the intensity and the last 6 millennia for the direction nevertheless the coverage still presents several gaps for periods older than 2500 bc in an effort to complete the greek curve and extend it to older times we present the archeointensity results from three neolithic settlements in northern greece the samples are of two different natures burnt structures from avgi 5250 150 bc and vasili 4800 200 bc as well as ceramics from dikili tash 4830 80 bc and vasili 4750 250 bc the samples have been subjected to standard rock magnetic analyses in order to estimate the thermal stability and the domain state of the magnetic carriers before archeointensity measurements surprisingly very few ceramic samples provided reliable archeointensities whereas samples from burnt structures presented a very good success rate complementary studies showed that a detailed examination of the matrix color following archeological information and classification standards can be a decisive test for pre selection of sherds in spite of these unsuccessful measurements from ceramics we obtained an intensity value of 73 5 1 1 t for dikili tash a higher value than the other data obtained in the same area during the same period however we do not have evidences for a technical artefact during the experiment the burnt structures yielded two reliable archeointensities of 36 1 1 8 t and 46 6 3 4 t for avgi and vasili respectively finally we achieved a new archeomagnetic dating for these sites by comparing these new archeointensity values combined to the directional measurements already published with the bulgarian secular variation curve these new results contribute to extend the greek secular variation reference curve towards older periods

temporal development of prograding beach shoreface deposits the holocene of kujukuri coastal plain eastern japan abstract prograding beach foreshore deposits with a basal ravinement bed are recognized from detailed ams 14c dating and grain size analyses of holocene deposits of the kujukuri coastal plain facing the pacific coast of japan the holocene deposits are about 20 m thick and consist of an upward shoaling beach foreshore succession that has a basal unconformity overlain by a thin layer of relatively coarse sand the unconformity is a downlap surface which originated from a ravinement surface the overall succession was formed by a prograding beach foreshore system during the highstand in sea level of the last 6000 years poorly preserved fossil shells enclosed in the thin layer of coarse sand at the base of the succession date from the transgressive stage in sea level before 6000 cal yr bp grain size distribution patterns are polymodal in the basal sand layer and unimodal in the remainder of the succession modal classes of the basal part are fine 3 3 2 6 medium 2 3 1 8 and coarse 1 2 1 0 the fine mode and the unimodal grain sizes define an overall upward coarsening trend which correlates with the upward shoaling succession in contrast the medium and coarse modes are restricted to the basal sand and are interpreted as related to the ravinement process the thin basal sand layer an admixture of these modal classes is interpreted as a type of ravinement deposit preserved during sea level highstand no transgressive deposit was preserved on the ravinement surface because sediment supply was so small that the sediment on this surface experienced thorough reworking by storm waves

sediment transport on dissipative intermediate and reflective beaches abstract in this paper we review and synthesize field measurements of suspended sediment transport on the shoreface of dissipative intermediate and reflective beach states the morphodynamic beach state continuum was originally established in the 1970s but at the time only hydrodynamic processes and morphologies in these various states were described since the early 1980s when sensors capable of resolving suspended sediment concentration at intra wave time scale became available many studies have examined suspended sediment transport by waves and currents on the shoreface the synthesis of this work shows that the two end states in the morphodynamic continuum which are the dissipative and reflective states exhibit relatively small rates of cross shore sediment transport and weak gradients in that transport which both ensure that the nearshore morphology is relatively stable the intervening intermediate beach states typically exhibit prominent bar topographies and in these states strong morphodynamic feedbacks between hydrodynamic processes and morphology create locally large transport rates and sharp transport gradients which is the reason for the dynamic nature of these beach states transport processes driving sediment onshore and offshore within beach states are discussed as well as the transport processes responsible for state transitions

late pleistocene barrier island development reconstructed from genetic classification and timing of erosional surfaces paleo tokyo bay japan abstract formative processes of a retrogradational barrier island system and associated transgressive erosional surfaces are reconstructed from the upper pleistocene kioroshi formation developed in paleo tokyo bay japan the kioroshi formation provides high quality sedimentary records of a preserved barrier island system three volcanic ash beds intercalated in the formation provide a high resolution chronostratigraphic framework the barrier island system of the kioroshi formation developed in a glacio eustatically forced sea level cycle during oxygen isotope stages 6 to 5e in the early stage of the transgression paleo tokyo bay was non barred and was exposed to the pacific ocean affected by open ocean wave processes shoreface erosion in such a non barred environment developed a wave ravinement surface rs1 rs1 overlies incised valley fill deposits formed in the earliest stage of the transgression and is overlain by shoreface deposits that are further overlain by embayment deposits such as lagoonal and flood tidal delta deposits formed during succeeding barrier development during the later stage of the same transgression associated with the formation and landward migration of the barrier chain tidal currents in tidal inlet and flood tidal deltas became active and a tidal ravinement surface trs was formed trs is developed on the base of tidal inlet and flood tidal delta deposits furthermore shoreface erosion on the open ocean side of the barrier chain eroded underlying embayment deposits and formed a secondary wave ravinement surface rs2 a chronostratigraphic surface in embayment deposits defined by a volcanic ash bed intersects trs and is eroded by rs2 this relationship together with associated facies architecture indicates diachroneity of the formation of these marine erosional surfaces associated with the retrogradational barrier island system

long term variations in palaeointensity we compile a dataset of reliable palaeointensity estimates based both on published work and on new data from basaltic glass the basaltic glass data more than double the number of reliable thellie

the steens mountain oregon geomagnetic polarity transition 2 field intensity variations and discussion of reversal models we carried out an extensive paleointensity study of the 15 5 0 3 m y miocene reversed to normal polarity transition recorded in lava flows from steens mountain south central oregon one hundred eighty five samples from the collection whose paleodirectional study is reported by mankinen et al this issue were chosen for paleointensity investigations because of their low viscosity index high curie point and reversibility or near reversibility of the strong field magnetization curve versus temperature application of the thellier stepwise double heating method was very successful yielding 157 usable paleointensity estimates corresponding to 73 distinct lava flows after grouping successive lava flows that did not differ significantly in direction and intensity we obtained 51 distinguishable complete field vectors of which 10 are reversed 28 are transitional and 13 are normal the record is complex quite unlike that predicted by simple flooding or standing nondipole field models it begins with an estimated several thousand years of reversed polarity with an average intensity of 31 5 8 5 t about one third lower than the expected miocene intensity this difference is interpreted as a long term reduction of the dipole moment prior to the reversal when site directions and intensities are considered truly transitional directions and intensities appear almost at the same time at the beginning of the transition and they disappear simultaneously at the end of the reversal large deviations in declination occur during this approximately 4500 1000 year transition period that are compatible with roughly similar average magnitudes of zonal and nonzonal field components at the site the transitional intensity is generally low with an average of 10 9 4 9 t for directions more than 45 away from the dipole field and a minimum of about 5 t the root mean square of the three field components x y and z are of the same order of magnitude for the transitional field and the historical nondipole field at the site latitude however a field intensity increase to pretransitional values occurs when the field temporarily reaches normal directions which suggests that dipolar structure could have been briefly regenerated during the transition in an aborted attempt to reestablish a stationary field changes in the field vector are progressive but jerky with at least two and possibly three large swings at astonishingly high rates each of those transitional geomagnetic impulses occurs when the field intensity is low less than 10 t and is followed by an interval of directional stasis during which the magnitude of the field increases greatly for the best documented geomagnetic impulse the rapid directional change corresponds to a vectorial intensity change of 6700 2700 nt yr 1 which is about 15 50 times larger than the maximum rate of change of the nondipole field observed during the last centuries the occurrence of geomagnetic impulses seems to support reversal models assuming an increase in the level of turbulence within the liquid core during transitions the record closes with an estimated several thousand years of normal polarity with an average intensity of 46 7 20 1 t agreeing with the expected miocene value however the occurrence of rather large and apparently rapid intensity fluctuations accompanied by little change in direction suggests that the newly reestablished dipole was still somewhat unstable

sedimentology and fractal based analysis of permeability data john henry member straight cliffs formation upper cretaceous utah u s a interpretation of depositional environments combined with field measurement of permeability for a portion of the upper cretaceous straight cliffs formation near escalante utah provides new results for understanding and modeling facies dependent perme ability variations offshore transition lower shoreface upper shore face and foreshore environments are interpreted for part of the john henry member on the basis of outcrop investigation using a newly designed drillhole minipermeameter probe permeability was measured for two of the facies within this unit lower shoreface bioturbated sand stone and upper shoreface cross bedded sandstone approximately 500 permeability measurements at a sample spacing of 15 cm were made along four vertical profiles and three horizontal transects o na6m 3 21 m outcrop permeability ranges from 41 to 1 675 millidarcies md in the bio turbated sandstone facies which is massive bedded moderately to well sorted and very fine to fine grained in contrast permeability ranges from 336 to 5 531 md in the moderately to moderately well sorted fine to medium grained cross bedded sandstone facies a high degree of variability in permeability of the cross bedded facies is caused by small scale variations in grain size and structure related to depositional processes the geometric mean permeability in the bio turbated sandstone is 253 md compared with 1 395 md in the cross bedded facies while the facies dependent differences in permeability k are ap parent and related to depositional and biological processes fractal based statistical analysis of the horizontal ln k increments yields near ly identical results for the bioturbated facies and the cross bedded fa cies possibly suggesting an underlying statistical commonality in the formation of both facies increment distributions from both facies ap pear similar with peaking around the mean ln k increments from the smaller vertical data set appear similar also but with a variance approximately 3 7 times larger than the horizontal value variance scaling analyses of horizontal and vertical data both yield a hurst co efficient near 0 26 which is characteristic of negative spatial correla tion of the increments the methodology developed herein offers a po tential high resolution alternative to existing methods for understand ing and characterizing subsurface properties

depositional architecture of a wave dominated clastic shoreline pilmatue member argentina linking dynamics and stratigraphic record of bar trough systems abstract bar trough morphologies are a dominant feature of modern wave dominated clastic shorelines despite these barred configurations being widely described from modern systems there is still some uncertainties associated with their interpretation in the ancient record there is a lack of detailed outcrop based studies describing the facies distribution and architecture within bar trough systems which causes a disparity between observations of modern processes and the subsequent preserved rock record this work presents a detailed characterization and interpretation of the sedimentary record of a bar trough setting this was achieved through the analysis of nearshore i e upper shoreface and foreshore deposits within a parasequence in the lower cretaceous pilmatue member of the agrio formation neuquen basin argentina a high resolution facies and architectural analysis was developed combining detailed sedimentary logs with the mapping of bounding and internal surfaces within the nearshore deposits the facies analysis suggests that trough and planar cross bedded facies are remnants of dunes in the upper shoreface due to a strong influence of longshore currents while planar laminated facies would be the result of swash processes in the foreshore additionally the presence of a well defined surf diastem the persistent low angle obliquity of palaeocurrents and the preservation of concave upward stratigraphic surfaces led to the interpretation of those deposits as representing the production of a bar trough configuration with longshore currents distributing large amounts of sediment along the shore this analysis allowed us to reconstruct the dominant processes for sediment transport and deposition within these barred nearshore settings and to identify different key architectural surfaces for the upper shoreface and foreshore deposits the architectural analysis of such surfaces led to define four different orders of hierarchy which respond to depositional and erosional processes operating at different scales the comparison between different resulting architectures of wave dominated barred shoreline offers the possibility to improve in the palaeoenvironmental reconstructions for ancient or recent successions the proposed model for bar trough clastic shoreline successions relates an absence of bar related deposits to major storms and shoreline erosional processes this conceptual model offers a new interpretation for explaining the mid scale evolution of bar trough settings and the relationship between the modern and ancient record

use of bed form climb models to analyze geometry and preservation potential of clastic facies and erosional surfaces based on a combination of walther s law of facies and bed form climb theory we propose a model that explains how erosion surfaces and vertical sequences of clastic strata are preserved where deposition occurs in channelized or locally erosional environments including fluvial and submarine channel deposits barred beaches and transgressive coastlines the model considers both lateral and vertical migration of a scour surface and its associated depositional products as in studies of bed form climb we recognize subcritical critical and supercritical climb of scour surfaces relative to adjacent depositional forms for a given erosion surface the amount of underlying material removed is dictated by the climb angle of the erosion surface preservation of sequences also d pends on whether conditions were relatively variable or invariable one important conclusion of this study is the recognition of the bed form climb angle s control on the thickness of a sedimentary facies estimates of paleochannel depth or paleowater depth based on facies thickness can be made only if the climb angle is zero by combining depositional models of fluvial nearshore and offshore facies it is theoretically possible to model depositional systems such as deltas and passive continental margins potential applications are limited by several factors including influence of sea level climatic fluctuations on sedimentation and variable migration of facies or nonideal behavior or sedimentary environments in addition negative climb angles or climb angles less than horizontal can result in the removal of large amounts of material such negative climb angles may be caused by drops in eustatic sea level and lowering of base levels of drainage systems we believe that this heuristic model has considerable potential in helping sedimentologists and stratigraphers predict the consequences of facies mi ration

paleomagnetic constraints on a time stratigraphic framework for the evolution of ohachidaira volcano and the summit caldera central hokkaido japan we present a revised stratigraphy of the proximal deposits around ohachidaira volcano and their paleomagnetic directions obtained from 21 sites 193 samples we identify four proximal pyroclastic members from ohachidaira volcano that were produced after the early edifice building effusive volcanism from older to younger 1 vent opening mafic pyroclastic density current pdc deposits kobachidaira ignimbrite 2 maar forming mafic tephra ring deposits mamiyadake tephra ring 3 mafic to silicic caldera forming deposits sounkyo member and 4 mafic pdc deposits kumonotaira ignimbrite well grouped paleomagnetic directions obtained from the kobachidaira ignimbrite and the sounkyo member indicate that each deposit was formed over a short time interval compared to geomagnetic secular variation that is less than a century conversely scattered paleomagnetic directions of the mamiyadake tephra ring record the secular variation of the geomagnetic field that took place over a longer time interval that is at least 750 yr probably more the kumonotaira ignimbrite which has a similar paleomagnetic direction to the underlying sounkyo member may have been produced during the sounkyo eruption from comparison between our data and the previously reported paleomagnetic directions of two petrologically distinct distal ignimbrites we conclude that the sounkyo member is a proximal correlative of the distal pyroxene rich ignimbrite and that the distal hornblende rich ignimbrite may not be of an ohachidaira origin the revised stratigraphy suggests that ohachidaira volcano is a maar caldera complex volcano and that the summit caldera is a flaring funnel formed incrementally by explosive erosion and syn eruptive collapse of the vent walls volume estimates imply that the sounkyo eruption fundamentally enlarged the vent and formed the caldera our data confirm that the comparison of paleomagnetic directions can offer a useful identification and correlation tool for the ohachidaira pyroclastic sequences

stratigraphic architecture of a net transgressive marginal to shallow marine succession upper almond formation rock springs uplift wyoming u s a abstract the upper part of the almond formation records the overall retreat of a wave dominated shoreline and associated lagoons or bays exposures of these strata on the eastern flank of the rock springs uplift wyoming u s a enable analysis of their stratigraphic architectures along sections oriented oblique to depositional strike the upper almond formation comprises at least nine vertically stacked regressive transgressive cycles the regressive component of each cycle consists of thick up to 22 m laterally continuous wave dominated shoreface and overlying coastal plain deposits that occur in paleoseaward locations and have abrupt 400 m paleolandward pinchouts the transgressive component of each cycle consists of one or more bay fill successions that occur in paleolandward locations and gradually thin in a paleoseaward direction transgressive bay fill deposits in each cycle are thick up to 18 m and associated with preservation of surfaces that record in progressively paleoseaward locations initiation of a lagoon or bay transgressive surface erosional retreat of tidal inlet channels tidal ravinement surface and the shoreface wave ravinement surface and marine flooding marine flooding surface this architecture records regression of a strandplain or wave dominated delta and subsequent transgression of a barrier island and spit with associated lagoon or bay the occurrence of such thick and fully preserved bay fill successions indicates that accretionary transgressive shoreline trajectories were developed strongly aggradational to weakly retrogradational stacking of successive regressive transgressive cycles results in a layered stratigraphic architecture with laterally continuous shoreface sandstone layers interbedded with bay fill shale layers shoreface sandstones layers pinch out up dip abruptly 400 m into bay fill shales and have limited vertical connectivity sandstones within bay fill and coastal plain deposits occur as small laterally discontinuous bodies of variable geometry and connectivity however these sandstones may provide additional connectivity where they erode through bay fill shales between two shoreface sandstone layers

experiments on trm intensity dependence on cooling rate palaeointensity studies have an important role to play in understanding the origin and time variation of the geomagnetic field however theoretical considerations indicate that the intensity of magnetization recorded by a rock or archaeological sample will be dependent on the rate at which it cooled as well as field magnitude experiments on synthetic magnetite and titanomagnetites of varying grain sizes indicate that for acicular magnetite at low concentration slower cooled trm is stronger than faster cooled trm but for all other samples slower cooled trm is weaker this is the predicted behaviour however the magnitude of the effect is much greater than the predicted kinetic effects and indicates that the magnetization of sub microscopic magnetite rich inclusions in the titanomagnetites strongly controls the trm intensity of the matrix

the lower permian wasp head formation sydney basin high latitude shallow marine sedimentation following the late asselian to early sakmarian glacial event in eastern australia the lower permian wasp head formation early to middle sakmarian is a 95 m thick unit that was depos ited during the transition to a non glacial period following the late asselian to early sakmarian glacial event in eastern australia this shallow marine sandstone dominated unit can be subdivided into six facies associa tions i the marine sediment gravity flow facies association consists of breccias and conglomerates deposited in upper shoreface water depths ii upper shoreface deposits consist of cross stratified conglomeratic sand stones with an impoverished expression of the skolithos ichnofacies iii middle shoreface deposits consist of hummocky cross stratified sandstones with a trace fossil assemblage that represents the skolithos ichnofacies iv lower shoreface deposits are similar to middle shoreface deposits but contain more pervasive bioturba tion and a distal expression of the skolithos ichnofacies to a proximal expression of the cruziana ichnofacies v delta influenced lower shoreface offshore transition deposits are distinguished by sparsely bioturbated carbo naceous mudstone drapes within a variety of shoreface and offshore deposits trace fossil assemblages repre sent distal expressions of the skolithos ichnofacies to stressed proximal expressions of the cruziana ichnofacies impoverished trace fossil assemblages record variable and episodic environmental stresses possibly caused by fluctuations in sedimentation rates substrate consistencies salinity oxygen levels turbidity and other physio chemical stresses characteristic of deltaic conditions vi the offshore transition offshore facies association con sists of mudstone and admixed sandstone and mudstone with pervasive bioturbation and an archetypal to dis tal expression of the cruziana ichnofacies the lowermost 50 m of the formation consists of a single deepening upward cycle formed as the basin transitioned from glacioisostatic rebound following the asselian to early sak marian glacial to a regime dominated by regional extensional subsidence without significant glacial influence the upper 45 m of the formation can be subdivided into three shallowing upward cycles parasequences that formed in the aftermath of rapid possibly glacioeustatic rises in relative sea level or due to autocyclic progra dation patterns the shift to a parasequence dominated architecture and progressive decrease in ice rafted de bris upwards through the succession records the release from glacioisostatic rebound and amelioration of cli mate that accompanied the transition to broadly non glacial conditions

geomagnetic field for 0 3 ka 1 new data sets for global modeling 1 paleomagnetic and archeomagnetic records are used in both regional and global studies of earth s magnetic field we present a description and assessment of five newly compiled data sets also used in the companion paper by korte et al 2009 to produce a series of time varying spherical harmonic models of the geomagnetic field for the last 3000 years data are drawn from our compilation of lake sediment records and from the online database geomagia50v2 the five selections are available from the earthref digital archive at http earthref org cgi bin erda cgi n 944 data are grouped according to the source of material and we conducted separate assessments of reliability for archeomagnetic artifacts and lava flows the arch3k dat data set and for sediments sed3k dat the overall number of data is 55 greater than in previous compilations constrained data sets were selected using different criteria for each group winnowing of archeological data was based on uncertainties supplied by the original data providers the lake sediment data assessment relied on preassigned age uncertainties and one or more of the following comparisons with archeomagnetic data from the same region regional consistency among several lakes and consistency with global archeomagnetic models we discuss relative merits of a larger unconstrained data set or a smaller possibly more reliable one the constrained data sets eliminate a priori up to 35 of the available data in each case and rely on potentially subjective assessments of data quality given the limited data available our analyses indicate that iterative rejection of a small number 1 1 5 of outlying data during global field modeling is a preferable approach specific regional comparisons among the models and data support the conclusion that korte et al s outlier free cals3k 3 model based on all available measurements from sediments and archeological artifacts currently provides the best global representation of the 0 3 ka field the arch3k 1 model provides a better fit to the denser european archeomagnetic data and may be better in that region

rock magnetic property and paleointensity determination on historical santorini lava flows eight historical dacitic lava flows from santorini with ages between 46 a d and 1950 a d four of them within the past century have been subjected to detailed rock magnetic analyses and various experiments of absolute paleointensity thermomagnetic measurements and acquisition of isothermal magnetization have revealed the presence of two physically distinct magnetic phases with curie temperatures of 280 c and 500 c in most of the samples the second phase does not play a prominent role for the characteristic remanent magnetization which is dominated by titanomagnetite magnetostatic interaction is very limited and does not considerably change upon heating back field curve spectra indicate a good thermochemical stability of these dacitic lava samples which is also supported by the absence of noticeable changes in the remanent coercive force prior heating to 450 c hysteresis measurements show typical pseudo single domain behavior without noticeable superparamagnetism such characteristics were favorable to conduct and to test the most widely used experimental approaches for absolute paleointensity determination despite a success rate of 38 the microwave technique has provided rather scattered within flow determinations the results obtained from approaches involving alternating field demagnetization were biased by considerable differences between the nrm and the trm coercive force spectra we have also noticed that most determinations obtained by microwave heating differ from the historical field value at the site for the most recent flows last techniques involving double heating protocols were successful due to a dominant low curie temperature phase with a narrow grain size distribution the results were characterized by low dispersion and were found in good agreement with the historical field

beach and nearshore facies southeast australia abstract the morphology texture and facies sequence on seven sand beaches located in low moderate and high wave energy microtidal environments in southern australia were investigated using box coring and scuba observations systematic variation in facies occur both within and between the beaches low energy reflective beaches are limited in lateral and vertical extent and in facies to beach laminations separated by coarse step deposits from finer nearshore cross lamination facies moderate energy intermediate beaches characterised by rip circulation possess increasingly wider surfzones with ridge and runnel and bar trough facies separating the beach and step facies from the more extensive nearshore sequence high energy dissipative beaches may have 500 m wide surfzones containing multiple bar trough topography fine beach laminations with backwash structures grade into 4 5 m thick bar trough sequences then the extensive nearshore facies as wave energy increases from low h b h b 2 5 m the vertical extent of the beach to nearshore sequence increases from

recognition and hydrologic significance of passive margin updip sequences an example from eocene coastal plain deposits u s a abstract sequence stratigraphic interpretations are extended to a passive margin updip setting using sedimentological observations from cores and well to well correlations in eocene coastal plain strata of south carolina in the succession studied formation contacts tend to follow sequence boundaries even as lithologies vary within individual sequences sequence boundaries at the base of the congaree formation and near the top of the tinker formation formed during relative sea level fall associated with second order global cycles these boundaries can be recognized clearly in both downdip and updip areas of the passive margin three other sequence boundaries which occur at the base and top of the warley hill formation and within the tinker formation are interpreted as formed during relative sea level fall associated with third order global cycles hydrostratigraphic units in the strata studied conform to depositional patterns that were controlled by changes in sea level and sediment influx sand of the gordon aquifer comprises a thick aggradational succession deposited predominantly in the nearshore shelf environment as accommodation increased during relative rise in sea level because of high rates of sedimentation in the proximal setting aggradational stacking of nearshore sands may be common to other updip marine strata in accommodation dominated regimes the overlying gordon confining unit consists of marine shelf clay and carbonate sediment deposited in response to maximum transgression during subsequent relative sea level fall accumulation of shoreface deposits produced a progradational succession that is represented by the lower part of the upper three runs aquifer unlike formation contacts boundaries between the clastic aquifers and confining units do not follow the third order sequence boundaries because of lithologic variations within the sequences an increasing degree of breaching through the gordon confining unit which results in downward contaminant migration into the gordon aquifer occurs in the updip direction because of nearly continuous sand deposition near the base of the interval studied contaminants migrate locally through the crouch branch confining unit because of erosional breaches formed by scour during sea level lowstand in this example and in other strata deposited in an updip passive margin setting the extent to which confining units are breached at sequence boundaries decreases in the downdip direction resulting in better protection of the adjacent aquifer

regional modeling of the geomagnetic field in europe from 6000 to 1000 b c we have developed a first low degree regional geomagnetic model for the european continent valid for the period 6000 1000 b c from a selected compilation of sedimentary and archeomagnetic data the scha dif 8k model this model provides information about both direction declination and inclination and intensity of the earth s magnetic field by connecting it with our previous model scha dif 3k valid from 1000 b c to 1900 a d and the igrf we furnish continuous geomagnetic field information for the last 8000 years in europe it has been developed using the revised spherical cap harmonic analysis in 2 dimensions technique r scha2d and using the norm of the earth s magnetic field to constrain the inversion problem the size of the cap is 22 and the maximum degree of the expansion is 2 the linearization problem was solved by using the truncated taylor s series applied to the expressions representing the relationship between the declination inclination and intensity data and the cartesian components of the geomagnetic field we used the geocentric axial dipole gad field as our initial or reference field for time we used the classical sliding overlapping window method the size of the window was set to 100 years shifted by 50 years we compared the model s prediction with the input data with the global cals7k 2 model and with new independent data the regional model shows a better fit to the input and to the independent data than the global model especially in terms of intensity and agrees with the virtual axial dipole moment given by other studies for the last 8000 years the european geomagnetic field has recorded rapid changes or archeomagnetic jerks the average field for the last 8000 years in europe is indistinguishable from the gad field

continuous geomagnetic field models for the past 7 millennia 1 a new global data compilation 1 a global data set of archeomagnetic and paleomagnetic data covering the past 7000 years has been compiled it consists of 16 085 results of inclination 13 080 of declination and 3188 of intensity for the time span 5000 bc to 1950 ad declination and inclination data come partly from existing databases and partly from original literature a new global compilation of intensity data for the millennial scale is included data and dating uncertainties are discussed as we attempted to obtain an internally coherent data set the global distribution of the data is very inhomogeneous in both time and space all the data are compared to predictions from the previous 3000 year global model cals3k 1 this collection of data will be useful for global secular variation studies and geomagnetic field modeling although southern hemisphere data are still underrepresented in particular we will use it in a further study to update and extend the existing global model cals3k 1 the huge increase in data compared to the previous compilation will result in significant changes from current models as we might have missed some suitable data we encourage the reader to notify us about any data that have not been included yet and might fit in as improving our global millennial scale models remains our aim for the future the data files described in this paper are available from the earthref digital archive erda at http earthref org cgi bin erda cgi n 331

scaling time integrated in situ cosmogenic nuclide production rates using a continuous geomagnetic model abstract spatial and temporal variations in earth s magnetic field affect the corresponding time integrated distribution of in situ cosmogenic nuclide cn production rates these effects can be quantified by the effective vertical cutoff rigidity r c a measure of the energy required for primary cosmic rays to penetrate the geomagnetic field and interact with the atmosphere at a given location recent cn production rate scaling models are based on atmospheric cosmic ray measurements parameterized using r c estimates derived from detailed modern geomagnetic field representations which include both dipole and non dipole field contributions however published methods for quantifying time integrated geomagnetic effects on cn production rate scaling rely on various geocentric dipolar approximations to r c driven by separate records of paleomagnetic pole position and paleointensity therefore applying dipolar paleomagnetic records spanning millennial time scales which explicitly ignore past non dipole effects to scaling models derived using modern geomagnetic field representations may lead to systematic errors in any calculated results a recently published continuous geomagnetic model covering the last 7 kyr cals7k 2 m korte and c g constable continuous geomagnetic field models for the past 7 millennia 2 cals7k 2005 geochem geophys geosyst 6 q02h16 doi 10 1029 2004gc000801 may allow reduction of such errors by bridging the gap between detailed modern geomagnetic and simplified paleomagnetic models we have developed a new model framework describing temporal and spatial variation in r c for 0 7 ka and earlier based on cals7k 2 which explicitly accounts for non dipole field effects while attempting to mitigate systematic scaling biases scaling factors derived using the new r c framework predict significant longitudinal variability in time integrated cn production while predictions using dipolar geomagnetic approximations do not one can test these predictions using in situ cosmogenic 14 c in situ 14 c in quartz due to its short half life 5 73 kyr 14 c attains secular equilibrium between production and decay after approximately 25 kyr of exposure at which point its measured concentration is only a function of its integrated average production rate initial in situ 14 c results from samples at secular equilibrium from 38 n and 3 5 km in tibet and eastern california are consistent with the longitudinal variability predicted by the new framework

facies and stratigraphic anatomy of a temperate carbonate sequence capo colonna terrace late pleistocene southern italy abstract accurate interpretation of ancient non tropical carbonate systems requires the development of appropriate facies and sequence stratigraphic models these models should account for the marked differences in sedimentation style among non tropical carbonates formed under different energy settings this paper presents data and a conceptual model of the sequence architecture of non tropical carbonates of moderate energy environments based on the late pleistocene deposits of capo colonna marine terrace calabria southern italy these deposits have the advantage of being continuously exposed along a proximal distal transect across the paleo shelf and their geometry has not been disturbed by later tectonic activity they consist of a transgressive regressive t r cycle whose genesis can confidently be related to one of the interstadial glacio eustatic fluctuations of marine isotope stage mis 5 eight different mixed carbonate siliciclastic and carbonate facies are present in the studied sequence of these biogenic dominated facies are invariably made up of skeletal remains of light independent organisms plus or minus red calcareous algae the heterozoan association the relatively young age of the deposits allows calibration of the paleoecological significance of observed facies by direct comparison with modern analogues from the mediterranean sea four laterally persistent discontinuity surfaces were identified along the transect and interpreted from bottom to top as 1 a basal ravinement surface 2 a submarine hardground locally acting as a substrate for algal boundstones 3 a regressive surface of marine erosion and 4 a surface of subaerial exposure sequence stratigraphic analysis indicates that the preserved t r cycle is asymmetric with a thicker regressive portion highstand deposits can be subdivided into a shore connected sandy prism and more distal autochthonous and parautochthonous skeletal accumulations and algal boundstones during forced regression a thin sharp based strongly progradational unit of calcarenites was deposited above the regressive surface of marine erosion the deposits of capo colonna terrace document the response of non tropical moderate energy carbonate ramps to sea level fluctuations during icehouse conditions their architecture can facilitate the interpretation of other successions from similar settings and provide an end member to be compared and contrasted with high wave energy cool water carbonates