de glauconiarum origine the glauconitic facies is widespread on present day continental shelves from 50 s to 65 n and at water depths between 50 and 500 m and is in particularly great abundance on the upper slope and outer shelf between 200 and 300 m it is also common in many ancient rocks of post late precambrian age it occurs as sand to pebble sized essentially green particles granular facies but also as a surface coating on particles and hardgrounds and as a diffuse impregnation film and diffuse facies we suggest the replacement of the term glauconite which has been interchangeably used to designate a morphological form and a specific mineral by glaucony facies and glauconitic smectite and glauconitic mica as end members of the glauconitic mineral family the widely accepted model of burst and hower for glauconitization requires a degraded micaceous 2 1 layer lattice structure parent clay mineral however detailed analysis of numerous samples of recent glaucony reveals that such a parent substrate is exceptional the model therefore requires modification generally the parent material is carbonate particles argillaceous kaolinitic faecal pellets infillings of foraminiferal tests various mineral grains and rock fragments that pass gradually into the commonly occurring green grains we show that the process of glauconitization is achieved by de novo authigenic growth of automorphous crystallites in the pores of the substrate accompanied by progressive alteration and replacement of the substrate it is this two fold evolution that causes the verdissement of granular substrates macrofossils and hardgrounds the authigenic mineral is an iron rich and potassium poor glauconitic smectite while new smectites are growing into the remaining pore space the earlier smectites are modified by incorporation of potassium producing decreasingly expandable minerals with a non expandable glauconitic mica as the end member this mineralogical diversity of the glauconitic mineral family explains the highly variable physical and chemical properties of glaucony four categories nascent little evolved evolved and highly evolved glaucony are distinguished glauconitization appears to be controlled by a delicate balance between degree of physical confinement of a particle and the amount of ionic exchange between the micro environment and ambient open marine sea water the optimum conditions for glauconitization are those of semi confinement as a result the interior of a grain is more glauconitized than its less confined periphery similarly for identical substrate types large grains 500 m provide more favourable substrates for glauconitization than lesser confined small grains on a larger scale the formation of glaucony is governed by the availability of iron and potassium and the balance between detrital influx and winnowing low accumulation rates expose grains to the open marine environment for sufficiently long times 105 106 years for highly evolved glaucony

exxon global cycle chart an event for every occasion the basic premise of the recent exxon cycle chart that there exists a globally correlatable suite of third order eustatic cycles remains unproven many of the tests of this premise are based on circular reasoning the implied precision of the exxon global cycle chart is not supportable because it is greater than that of the best available chronostratigraphic techniques such as those used to construct the global standard time scale correlations of new stratigraphic sections with the exxon chart will almost always succeed because there are so many exxon sequence boundary events from which to choose this is demonstrated by the use of four synthetic sections constructed from tables of random numbers a minimum of 77 successful correlations of random events with the exxon chart was achieved the existing cycle chart represents an amalgam of regional and local tectonic events and probably also includes unrecognized miscorrelations it is of questionable value as an independent standard of geologic time

high resolution sequence stratigraphy of lower paleozoic sheet sandstones in central north america the role of special conditions of cratonic interiors in development of stratal architecture well known difficulties in applying sequence stratigraphic concepts to deposits that accumulated across slowly subsiding cratonic interior regions have limited our ability to interpret the history of continental scale tectonism oceanographic dynamics of epeiric seas and eustasy we used a multi disciplinary approach to construct a high resolution stratigraphic framework for lower paleozoic strata in the cratonic interior of north america within this framework these strata proved readily amenable to modern sequence stratigraphic techniques that were formulated based on successions along passive margins and in foreland basins settings markedly different from the cratonic interior parasequences parasequence stacking patterns systems tracts maximum flooding intervals and sequence bounding unconformities can be confidently recognized in the cratonic interior using mostly standard criteria for identification the similarity of cratonic interior and foreland basin successions in size geometry constituent facies and local stacking patterns of nearshore parasequences is especially striking this similarity indicates that the fundamental processes that establish shoreface morphology and determine the stratal expression of retreat and progradation were likewise generally the same despite marked differences in tectonism physiography and bathymetry between the two settings our results do not support the widespread perception that paleozoic cratonic interior successions are so anomalous in stratal geometries and constitute such a poor record of time that they are poorly suited for modern sequence stratigraphic analyses the particular arrangement of stratal elements in the cratonic interior succession we studied is no more anomalous or enigmatic than the variability in architecture that sets all sedimentary successions apart from one another thus paleozoic strata of the cratonic interior are most appropriately considered as a package that belongs in a continuum of variable stratigraphic packages reflecting variable controls such as subsidence and shelf physiography special conditions of exceptionally slow subsidence rate shallow bathymetry and nearly flat regional shelf gradient are manifest mostly by the presence of individual systems tracts of relatively long duration that extend for much greater distances across depositional strike than those that characterize successions deposited in more dynamic tectonic and physiographic settings these results suggest that if other cratonic interior successions are as anomalous as reported a low sediment supply may have played a primary role in development of their apparently condensed stratal architecture the results also lead us to suggest that a nonvegetated lower paleozoic landscape played a relatively insignificant role in the development of what are commonly perceived to be enigmatic stratigraphic features of sheet sandstones particularly their widespread yet thin geometry and a scarcity of shale and siltstone

structure and composition of organic reefs and carbonate mud mounds concepts and categories defined here as essentially in place calcareous deposits created by sessile organisms organic reefs are diverse and complex structures with a long geological history their classification has been the subject of fierce debate often characterized by reliance on subjective features such as wave resistance and qualitative attempts to discriminate between first and second class reefs in contrast emphasis is here placed on the objective characteristic of the type of sedimentary support which largely determines the sedimentary composition of the deposit constructional and depositional processes result in three principal sedimentary components matrix m essentially in place skeletons s and cavity cement c whose proportions can be represented on msc triangular plots separately or together these components also provide the structural support for the reef on these compositional and structural bases three main categories of organic reef are recognized 1 matrix supported reefs agglutinated microbial reefs cluster reefs segment reefs 2 skeleton supported reefs frame reefs 3 cement supported reefs cement reefs agglutinated microbial reefs possess laminated clotted or aphanitic fabrics created by microbial trapping of particulate sediment in place skeletons and large primary cavities are rare early cementation may provide added support topographic relief is limited by the need for currents to provide sediment to accreting surfaces cluster reefs skeletal reefs in which essentially in place skeletons are adjacent but not in contact resulting in matrix support characterized by relatively high matrix skeleton ratios and low volumes of extra skeletal early cement sediment trapping is an important corollary of skeletal growth and cluster reef organisms are tolerant of loose sediment absence of framework limits the topographic relief that cluster reefs can attain relative to spatial extent and may permit bedding to develop within the reef close cluster reefs have skeletons up to 1 unit distance apart spaced cluster reefs have skeletons more than 1 and up to 2 unit distances apart with increasing separation of skeletons they grade to level bottom communities segment reefs matrix supported reefs in which skeletons are adjacent and may be in contact but are mostly disarticulated and mainly parauthochtonous matrix abundance is high and early cement relatively low moderate relief can develop in response to intense on reef sediment production frame reefs skeletal reefs in which essentially in place skeletons including calcified microbes are in contact characterized by relatively high skeleton matrix ratio skeletal support enables them to raise themselves above the substrate independently of cementation and particulate sedimentation simultaneously by creating partly open shelter cavities skeletal support may facilitate early cementation both relief and early lithification promote marginal talus formation skeletal shape and orientation distinguish conical stick like dendritic domical and laminar frames each of these may be open or filled open frame reefs

sea level driven changes in ocean chemistry at an upper cambrian extinction horizon a combined stratigraphic and isotopic study across a late cambrian mass extinction horizon pterocephaliid ptychaspid biomere boundary in cratonal and miogeoclinal sections of the western united states reveals evidence for a pattern of sea level rise decreasing 87 sr 86 sr ratios and increasing 13 c the positive shift in 13 c reaching maximum values a few metres above the extinction interval is interpreted to reflect elevated primary productivity and an increase in the rate of burial of organic matter during expansion of the oxygen minimum zone the 87 sr 86 sr decrease is interpreted to reflect some combination of increased sea floor spreading rates and decreased continental weathering rates the 13 c and 87 sr 86 sr trends independently support the field based hypothesis that a sea level rise led to catastrophic oceanic overturn possibly culminating in anoxic conditions that ultimately proved lethal to a large fraction of the existing shelf fauna

an example of an accretionary forearc basin from northern central anatolia and its implications for the history of subduction of neo tethys in turkey deformed sedimentary sequences of late cretaceous middle eocene age located between the sakarya continent and the anatolian complex have been interpreted as the fill of a forearc basin the history and structure of this basin are critical for understanding the evolution of the neo tethyan subduction in the middle east i test and elaborate upon this interpretation on the basis of three basic outcrop areas of upper cretaceous lower tertiary sedimentary sequences confined to a northeast southwest trending belt in north west ankara these are the alci kinik and orhaniye areas they expose two different sedimentary sequences called alci and orhaniye in the alci area the sequence starts at the base with the continental red clastic rocks on the erosional surface of an underlying ophiolitic melange and continues upward into the shallow marine reefal buildup of the late maastrichtian age the upper half of the alci sequence is separated from its lower half by a local disconformity and dominated by the continental debris flow deposits composed mostly of volcanic material by contrast both the kinik and orhaniye areas are characterized by a thick continuous and coarsening upward sequence overlying conformably the underlying ophiolitic melange the lower half of the orhaniye sequence is dominated by a deep marine flysch its middle part by continental clastic material and the topmost part by the shallow marine reefal buildup lower contact relationships lithologic composition facies distribution internal structures and the regional tectonic settings of both sequences strongly suggest that the above mentioned three outcrops preserve the remnants of a peripheral accretionary forearc basin forming the north northwestern margin of the haymana polath accretionary forearc basin during middle campanian middle eocene time this peripheral basin is here named orhaniye accretionary forearc basin

reassessment of the age and depositional environments of the eocene cayraz formation a reference unit for tethyan larger benthic foraminifera haymana basin central turkey abstract the cayraz formation a reference unit for tethyan ypresian middle late lutetian larger benthic foraminifera haymana basin central turkey is a thick 350 m shallow marine mixed carbonate siliciclastic sequence divided into lower middle and upper units the lower and upper units predominantly consist of rhythmic intercalations of limestone and marly silty beds with abundant larger benthic foraminifera lbf and the middle unit is composed of massive fine siliciclastic sediments mostly barren in lbf and macrofossils by studying three sections caya cayb and ye encompassing the lower unit we show that the cayraz formation ca 100 m thick displays notable vertical and lateral variability in benthic fauna and facies along an se nw transect at its type locality near cayraz village the distribution of lbf and facies patterns indicate a general shallowing upward trend with more open marine environments in the easterly section caya and restricted shallow marine to continental environments with low diversity fauna in the westerly section ye a depositional setting ranging from outer to inner ramp with continental influence only in the westerly section is proposed key orthophragminid and alveolinid taxa from the lower unit of the cayraz formation indicate shallow benthic zones sbz 9 10 for its lower part and sbz 12 for its upper part suggesting a late ypresian age the massive marly silty section of the middle unit of the cayraz formation overlies the alveolina bearing limestones in all sections and yielded abundant planktonic foraminifera suggestive of p9 zone this implies a sharp environmental transition from platform to basin across the ypresian lutetian boundary

three new upper cambrian stages for north america the existing upper cambrian stages for north america are obsolete three new stratotype defined stages are equivalent to and replace three successive biomeres marjuman stage replaces marjumiid biomere lower boundary at base ptychagnostus atavis zone steptoean stage replaces pterocephaliid biomere lower boundary at base aphelaspis zone sunwaptan stage replaces ptychaspid biomere lower boundary at base irvingella major subzone the base of the overlying ibexian series is placed at the base of the eurekia apopsis subzone

comparative analysis of methods used to define eustatic variations in outcrop late cambrian interbasinal sequence development interbasinal correlation of late cambrian cyclic carbonates from the appalachian and cordilleran passive margins the texas craton and the southern oklahoma aulacogen defines six major third order depositional sequences graphic correlation of biostratigraphically constrained strata was used to establish equivalency of stratigraphic sequences between the individual sections relatively isochronous biomere boundaries were used as time datums for lithostratigraphic correlation although the individual sections are composed of different types of meter scale cycles and component lithofacies that reflect the various environmental settings of the localities the overall upward shallowing character of individual sequences is evident the sequences are late cedaria mid crepicephalus late crepicephalus aphelaspis to earliest elvinia elvinia to early saukia and saukia to the cambrian ordovician boundary interbasinal correlation of stratigraphic sequences permits an evaluation of quantitative techniques for determining accommodation history correlation of fischer plots of cyclic successions from separate basins supports a eustatic control of late cambrian sequence development r2 r3 curves derived from subsidence analysis of the late cambrian sections provide good resolution of the second and third order scales of accommodation change and interbasinal correlations of r2 r3 curves also support eustatic control on sequence development comparing the accomodation curves and subsidence analysis with paleobathymetric trends of late cambrian cyclic strata suggests that themore curves may approximate the form of the eustatic sealevel signal a composite eustatic sealevel curve for late cambrian time in north america was created by qualitatively combining the accommodation curves defined by the different techniques for each of the four localities 129 refs 16 figs 3 tabs less

the relationship between joint aperture spacing distribution vertical dimension and carbonate stratification an example from the kimmeridgian limestones of pointe du chay france joint aperture and joint development have been studied in the kimmeridgian limestones of the pointe du chay at the northern boundary of the jurassic biscay basin france at belette outcrop in some layers the mean joint spacing of the n120 joint set is close to mean layer thickness there the classical spacing to thickness relationship appears to be valid in the competent carbonate layers that are included in a more argillaceous matrix at pillar outcrop the n10 joint set is characterised by a high level of joint density and a non saturated spacing distribution as indicated by the mode mean ratio values and the cv values cv is the ratio of standard deviation to mean fracture spacing the classical relationship between layer thickness and fracture spacing has not been observed at the pillar outcrop joint aperture reaches larger values at the pillar outcrop than at the belette outcrop where aperture is more homogeneously distributed almost all the joints are opened with moderate aperture values at belette outcrop whereas most joints with large vertical dimension have large apertures at pillar outcrop and smaller fractures are closed or poorly opened from two outcrops that have been subjected to the same geological conditions apertures of non stratabound joints appear to be controlled by the vertical dimension of the joints whereas stratabound joints are more regularly spaced and opened

microbial sand chips a non actualistic sedimentary structure abstract microbial mats show a marked decline with the transition from the precambrian to the phanerozoic most likely due to the advent of effective benthic grazing organisms hitherto most aquatic sediments up to sand grade were commonly coagulated by organic material allowing reworking to form intraclasts new term microbial sand chips presence of a microbial mat is indicated 1 by refractory remains of organic matter in the laminated parent sediment 2 by the concentration of early diagenetic pyrite associated with sandy intraclasts in quartzites indicating a concentration of organic matter in the clast and 3 by plastic deformation of the clasts during the erosive event as bioturbation spread into most aquatic depositional environments during the phanerozoic the formation of microbial sand chips became restricted to habitats where bioturbation and grazing are limited by environmental stress and where the preservation potential for microbial sand chips is very low therefore the widespread formation of microbial sand chips in precambrian sandy subaqueous sediments is non actualistic

environmental biogeochemical characteristics of rare earth elements in soil and soil grown plants of the hetai goldfield guangdong province china very few studies deal with the biogeochemical behaviors of rare earth elements rees in goldfields this paper presents the geochemical and biogeochemical characteristics of rees within the soil plant system in the hetai goldfield guangdong china the samples from the goldfield region show anomalies in distribution patterns and behavioral characteristics of rees as compared with those from the background areas the rees in rocks soils and plants prove to be much higher than those in the surrounding regions the distribution patterns of rees are characterized by lree enrichment and hree depletion with the ree concentrations in layer a being the highest differentiations between lrees and hrees may lead to some extent of negative eu anomaly in the soils research results demonstrate that the rees in a soil profile can be transferred and accumulated during the mineral formation and supergenic geochemical processes and the anomalies are obviously related to the geological settings for the ree bearing ore forming processes and to the geochemical characteristics of the habitats for the ree bearing plants for dicranopteris dichotoma the total amount of rees in the tissues shows an order of leaf root stem while for pinus massoniana the order becomes root leaf stem the distribution patterns of rees in pinus massoniana leaves are similar to those in soils where the plants grow up in the mineralization area however in the background areas the ree distribution patterns for pinus massoniana stems are similar to those for soils where the plants grow up parameters such as biological absorption coefficients and biological transfer coefficients show the differences in ree absorption features among plants and indicate that rees can be transferred among plant organs the two coefficients can reveal the different survival mechanisms for the two plant species which are subject to long term ree affected stress conditions in the gold mineralization zone

influence of metaluminous granite mineralogy on the rare earth element geochemistry of rocks and soils along a climosequence in brazil abstract the borborema province in northeast brazil represents the western portion of the extensive geological brasiliano pan african orogenic system it is characterized by voluminous granites which originate from the melting of igneous rocks we investigated the influence of metaluminous granite mineralogy on the geochemistry of rare earth elements rees in rocks and soils across a climosequence mineralogical petrographic geochemical and soil analyses were used to examine the geochemistry of rees in these samples results showed that the granites had a high proportion of accessory minerals such as allanite titanite apatite amphibole and opaque minerals bastnaesite is the major source of light rees in rock and soil samples the high ree fractionation present in metaluminous granites was normalized to the upper continental crust and it was indicative of magma fractionation la yb n and light ree heavy ree ratios showed that weathering processes had a significant impact on ree fractionation in soil profiles the highest lree hree fractionation was found in the humid zone almost all primary minerals were transformed into secondary minerals except for quartz typical kaolinitic soils developed in this climatic zone as well thus the highest lree hree fractionation was mainly associated with the abundance of kaolinites which preferentially adsorbed lrees soil profiles developed from metaluminous granites in different climatic conditions showed similar ree signatures and there was enrichment for lrees over hrees negative ce anomaly and positive eu anomaly were also observed the correlation between the index of alteration cia and lree hree ratios suggest that ree fractionation could be used to evaluate the degree of granite weathering linear regression analyses showed that ree fractionation was useful for predicting weathering intensity of soils that derived from metaluminous granites however further research is warranted to explore the influence of other types of granite on the ree geochemistry of soils in addition to seeking ree ratios that could be used to estimate weathering rates of granites in tropical environments

depositional facies of high energy beach to offshore sequence comparison with low energy sequence a study of the nearshore zone and continental shelf of a high energy coast was made in the ventura port hueneme area of california during the summer of 1974 to investigate depositional facies characteristics and compare them with similar facies from a low energy coastal setting analysis of box cores can cores and vibracores permits recognition of three principal zones 1 nearshore facies backshore to 9 m water depth made up primarily of parallel ripple and cross bedded clean sand bioturbation is only locally significant 2 transition facies 9 to 18 m water depth a zone of fine sand and silty sand characterized by an increase in biogenic over physical sedimentary structures that are commonly preserved as laminated to burrowed beds wave ripple bedding and parallel lamination are important structures in this facies 3 offshore facies 18 m water depth sandy silt is the primary texture and bioturbation is the dominant sedimentary structure remnant parallel lamination is the only physical sedimentary structure present comparison of the results of this study with a previous description of a low energy beach to offshore sequence at sapelo island georgia indicates that the two areas do not differ greatly in their facies or overall vertical sequence of sedimentary structures the principal difference is in the thickness of the three facies the california facies are significantly thicker than their georgia counterparts this difference is in direct response to the role of higher wave energy on the california coast

implications of carbonate like geochemical signatures in a sandstone aquifer radium and strontium isotopes in the cambrian jordan aquifer minnesota usa water rock interaction in sandstone aquifers can potentially mobilize u and th series radionuclides resulting in elevated levels of radioactive constituents such as radium ra in groundwater previous studies have delineated the sources of ra in groundwater by assuming that 228ra 226ra of groundwater parallels the 232th 238u activity ratio of aquifer solids we present an integrated geochemical and isotopic study of groundwater and aquifer solids for major and trace elements radium 224ra 226ra 228ra strontium isotopes 87sr 86sr and tritium in the cambrian jordan quartz sandstone aquifer of southeastern minnesota usa the jordan aquifer part of the cambrian ordovician aquifer system of the upper midwestern usa is characterized by a wide range of ra activities in groundwater uniform ca mg hco3 major element composition and patterns in 87sr 86sr indicate that interaction with carbonate minerals controls water chemistry at least one contributing sr source is radiogenic yielding 87sr 86sr ratios up to 0 71347 radium 226 activities exhibit especially large variations 1 418 mbq l 1 and the highest radium activities occupy a 100 km long north south region consistent with the carbonate like elemental and sr isotope signatures 226ra activity median 85 mbq l 1 is higher than 228ra median 47 mbq l 1 yielding low 228ra 226ra ratios median 0 5 that would be expected from a lithology preferentially containing u relative to th such as carbonate rocks collectively results indicate the primary source of radium to the aquifer is alpha recoil from aquifer solids rather than external inputs of high ra waters indicated by 1 similar 228ra 226ra ratios in aquifer solids and groundwater including low carbonate like values in the high 226ra samples 2 some association between whole rock 226ra levels and groundwater 226ra activities and 3 groundwater 224ra 228ra averaging near unity furthermore hydrogeologic setting e g presence or absence of overlying carbonate units is inconsistent with systematic inputs of high ra waters from overlying carbonate aquifers the most proximate source of carbonate material in the sandstone aquifer seems to be the calcite and dolomite cement that yields different geochemical and isotopic fingerprints than silicate minerals would impart whole rock 226ra 238u 1 implies that any u enrichment in the carbonate cement occurred at least 350 000 years ago high groundwater ra activities relative to solids are attributable to anoxic conditions that play a role in maintaining inefficient radium removal for a fresh groundwater system indicated by the estimated dimensionless whole rock ra distribution coefficient of 150 920 median 560 coprecipitation of ra into barite is a potential but unquantified ra removal mechanism overall radium in the jordan aquifer provides an example of a naturally occurring trace element of health significance that may be derived not mainly from the quartz sandstone matrix but from carbonate material such as calcite and dolomite cement especially when combined with complementary tracers such as 87sr 86sr this study demonstrates the usefulness of the 228ra 226ra ratio as an indicator of the key mineral phases silicate vs carbonate involved in supplying radium to groundwater

frac sand crushing characteristics and morphology changes under high compressive stress and implications for sand pack permeability sand consisting of round quartz grains is widely used as a proppant during hydraulic fracturing to produce natural gas from tight shale formations this paper presents results from sand characteriz

bioaccumulation and translocation of rare earth elements in two forage legumes grown in soils treated with coal fly ash abstract coal fly ash cfa is often used as a soil amendment to improve the physicochemical properties of the soil however cfa contains abundant rare earth elements rees which may negatively affect plant growth and physiology and cause environmental hazards we performed pot experiments to grow alfalfa medicago sativa l and erect milkvetch astragalus adsurgens pall in soils treated with different rates of cfa in order to investigate the impacts of cfa on the accumulation and translocation of rees such as lanthanum la cerium ce scandium sc and yttrium y the results showed that la ce sc and y concentrations were considerably higher in the cfa than in soils but adding cfa to soils did not always significantly increase their concentrations in plants the element abundance in soils and cfa always followed the order of ce la y sc but the element bioaccumulation factor was generally in the order of sc y la ce in plants la ce sc and y concentrations generally followed the order of root shoot and leaf stem with ce concentrations being always higher than la and y concentrations most of these elements absorbed were sequestered in roots without being further transported to the aerial parts the root to shoot translocation factor of sc was the highest but the stem to leaf translocation factor of sc was the lowest among the elements studied the biogeochemical behaviours of sc were quite different from those of la ce and y adding cfa to the soils often considerably increased the amounts of la ce sc and y accumulated in shoots due to significant biomass increase furthermore ree speciations in the topsoil can be changed by both cfa addition and plant recycling therefore land application of cfa for revegetation and soil reclamation proposes can affect the biogeochemical behaviours of la ce sc and y

tidal bundle sequences in the jordan sandstone upper cambrian southeastern minnesota u s a evidence for tides along inboard shorelines of the sauk epicontinental sea abstract this study documents for the first time tidal bundling in a lower paleozoic sheet sandstone from the cratonic interior of north america providing insights into the hydrodynamics of ancient epicontinental seas the jordan sandstone upper cambrian in the upper mississippi valley contains large scale planar tabular cross sets with tidal bundle sequences which were analyzed in detail at an exceptional exposure tidal bundle sequences neap spring neap cycles were delineated by foreset thickening thinning patterns and composite shale drapes the latter of which represent accumulations of mud during the neap tides of neap spring neap tidal cycles fourier analysis of the bundle thickness data from the 26 measurable bundle sequences revealed cycles ranging from 15 to 34 bundles per sequence which suggests a semidiurnal or mixed tidal system along this part of the late cambrian shoreline we extend the tidal interpretation to widespread occurrences of the same facies in outcrops of lesser quality where the facies is recognizable but too few bundles are exposed for tidal cycles to be measured by doing so this study shows that tidally generated deposits have a significant geographic and temporal extent in upper cambrian strata of central mid continent north america the deposition and preservation of tidal facies was related to the intermittent development of shoreline embayments during transgressions the tidally dominated deposits filled ravined topographies that were repeatedly developed on the updip parts of the shoreface resulting coastal geomorphologies accompanied perhaps by larger scale changes in basinal conditions and or configuration led to changes in depositional conditions from wave dominated to tide dominated outcrops of the jordan sandstone tidal facies in the upper mississippi valley represent the farthest inboard recorded transmission of ocean generated tides in the laurentian epicontinental seas demonstrating that tidal currents were significant agents in the transport of sand along the far cratonic interior shorelines of cambrian north america the results of this study improve the facies level understanding of the genesis of sheet sandstones furthermore tidalites documented here occur in a specific position within a sequence stratigraphic architecture for the jordan sandstone this provides a framework to compare these ancient deposits and processes to younger e g carboniferous epicontinental systems where stratal and sediment dynamics are better documented

tidal deposition in the basal upper cambrian mt simon formation in wisconsin the upper cambrian mt simon formation 0 65 m thick is a basal quartz arenite exposed in westcentral wisconsin a detailed field investigation of the physical and biogenic sedimentary structures of the mt simon has led to the recognition of three distinct lithofacies the lower one unconformably overlies precambrian basement rocks it consists of medium to very large scale sets of tabular and trough cross bedded medium to very coarse grained sandstone and pebbly sandstone with minor intercalated horizontal beds of very fine to medium grained sandstone siltstone and shale sparse examples of skolithos and arenicolites are present this facies consists of a very thin sequence of possible braided fluvial and marine foreshore deposits overlain by probable marine shoreface and tidal channel deposits much of the facies seems to represent shallow subtidal deposition in a relatively high energy regime the middle lithofacies consists of two distinctly different subfacies which probably were deposited in a low tidal flat setting the higher energy subfacies consists of small to medium scale sets of tabular and trough crossbedded fine to coarse grained sandstones containing distinct zones dominated by skolithos and arenicolites this subfacies probably represents deposition in meandering tidal channels the lower energy subfacies consists of thinbedded horizontally laminated and ripple cross laminated very fine to medium grained sandstone siltstone and shale with common specimens of cruziana rusophycus and planolites this subfacies probably represents deposition on lower energy tidal flats adjacent to the tidal channels the upper lithofacies consists predominantly of structureless densely bioturbated very fine to coarse grained sandstone containing abundant specimens of skolithos the upper few meters of the facies consists of small to medium scale sets of trough cross bedded very fine to coarse grained sandstone with layers of disarticulated valves of the brachiopod obolus the upper facies probably represents deposition on tidal flats perhaps in a midtidal flat setting characterized by slower sedimentation rates a correspondingly higher degree of bioturbation persistent reworking of shelled macrobenthos and periodic subaerial exposure the mt simon formation is interpreted as a largely progradational regressive shoaling and fining upward tidal sequence a marine interpretation is supported by the widespread occurrence of marine trace fossils within this unit evidence for a tidal origin is seen in the presence of unimodal cross strata associated with reactivation surfaces compound cross strata numerous scour and truncation surfaces lined with intraformational conglomerates common clay drape laminae separating sets of cross strata interference and flat topped ripple marks and desiccation cracks sedimentation continued without apparent interruption as the overlying eau claire formation was deposited also under tidal influence recent reinterpretations of other basal cambrian cratonic quartz arenites together with this new interpretation for the mt simon formation suggest that the long held concept of basal transgressive sandstones deposited as blankets across the craton may be too simplistic for deposition in braided fluvial marginal marine tidal flat tidal channel and marine foreshore and shoreface environments seems indicated

flat pebble conglomerate its multiple origins and relationship to metre scale depositional cycles carbonate flat pebble conglomerate is an important component of precambrian to lower palaeozoic strata but its origins remain enigmatic the upper cambrian to lower ordovician strata of the snowy range formation in northern wyoming and southern montana contain abundant flat pebble conglomerate beds in shallow water cyclic and non cyclic strata several origins of flat pebble conglomerate are inferred for these strata in one case all stages of development of flat pebble conglomerate are captured within stormdominated shoreface deposits of hummocky cross stratified hcs fine carbonate grainstone a variety of synsedimentary deformation structures records the transition from mildly deformed in situ stratification to buckled beds of partially disarticulated bedding to fully developed flat pebble conglomerate these features resulted from failure of a shoreface and subsequent brittle and ductile deformation of compacted to early cemented deposits failure was induced by either storm or seismic waves and many beds failed along discrete slide scar surfaces centimetre scale laminae within thick amalgamated hcs beds were planes of weakness that led to the development of platy clasts within partly disarticulated and rotated bedding of the buckled beds in some cases buckled masses accelerated downslope until they exceeded their internal friction completely disarticulated into clasts and transformed into a mass flow of individual cm to dm scale clasts this transition was accompanied by the addition of sand sized echinoderm rich debris from local sources which slightly lowered friction by reducing clast clast interactions the resulting dominantly horizontal clast orientations suggest transport by dense viscous flow dominated by laminar shear these flows generally came to rest on the lower shoreface although in some cases they continued a limited distance beyond fairweather wave base and were interbedded with shale and grainstone beds the clasts in these beds show no evidence of extensive reworking i e not well rounded or condensation i e no rinds or coatings a second type of flat pebble conglomerate bed occurs at the top of upward coarsening metre scale cycles the flat pebble conglomerate beds cap these shoaling cycles and represent either lowstand deposits or in some cases may represent transgressive lags the clasts are well rounded display borings and have iron rich coatings the matrix to these beds locally includes glauconite these beds were considerably reworked and represent condensed deposits thrombolites occur above the flat pebble beds and record microbial growth before initial transgression at the cycle boundaries a third

on the age of the early middle eocene boundary and other related events cyclostratigraphic refinements from the pyrenean otsakar section and the lutetian gssp an integrated bio magneto and cyclostratigraphic study of the ypresian lutetian early middle eocene transition along the otsakar section resulted in the identification of the c22n c21r chron boundary and of the calcareous nannofossil cp12a b zonal boundary the latter is the main correlation criterion of the lutetian global stratotype section and point gssp recently defined at gorrondatxe basque country by counting precession related mudstone marl couplets of 21 ka the time lapse between both events was calculated to be 819 ka this suggests that the age of the cp12a b boundary and hence that of the early middle eocene boundary is 47 76 ma 250 ka younger than previously thought this age agrees with and is supported by estimates from gorrondatxe based on the time lapse between the lutetian gssp and the c21r c21n boundary the duration of chron c21r is estimated at 1 326 ma given that the base of the eocene is dated at 55 8 ma the duration of the early eocene is 8 ma 0 8 ma longer than in current time scales the otsakar results further show that the bases of planktonic foraminiferal zones e8 and p10 are younger than the cp12a b boundary the first occurrence of turborotalia frontosa being approximately 550 ka older that the cp12a b boundary is the planktonic foraminiferal event that lies closest to the early middle eocene boundary the larger foraminiferal sbz12 13 boundary is located close to the cp12a b boundary and correlates with chron c21r not with the c22n c21r boundary

planktonic foraminiferal biostratigraphy microfacies analysis sequence stratigraphy and sea level changes across the cretaceous paleogene boundary in the haymana basin central anatolia turkey abstract the cretaceous paleogene k pg boundary in the haymana basin central anatolia turkey was delineated using planktonic foraminiferal biostratigraphy microfacies analysis and sequence stratigraphy an 29 m outcrop consisting of limestone and marl was measured and four planktonic foraminiferal biozones were identified spanning the boundary planktonic foraminiferal extinction across the k pg boundary was catastrophic and abrupt the extinction level is overlain by a unit zone p0 showing an increase in echinoid fecal pellets and authigenic clay minerals such as glauconite suggesting low sedimentation rates in the early danian ten microfacies types were identified indicating inner ramp to basinal paleoenvironments based on the sedimentological characteristics and microfossil and macrofossil assemblages maastrichtian carbonates contain large benthic foraminifera calcareous red algae bryozoans fragments of echinoderms and mollusks and planktonic foraminifera overlying maastrichtian danian silty marls and silty limestones have common planktonic and benthic foraminifera progradation of carbonates into the basin took place during the highstand systems tract and deposition of a silty marl succession occurred during the transgressive systems tract the k pg boundary is in the upper part of the transgressive systems tract below a maximum flooding surface sequence stratigraphic analysis of a second section campo pit new jersey usa showed that the k pg boundary occurs within a transgressive systems tract in new jersey as well suggesting a global sea level rise across the k pg boundary

review and revision of cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale planktonic foraminifera are widely utilized for the biostratigraphy of cretaceous and cenozoic marine sediments and are a fundamental component of cenozoic chronostratigraphy the recent enhancements in deep sea drilling recovery multiple coring and high resolution sampling both offshore and onshore has improved the planktonic foraminiferal calibrations to magnetostratigraphy and or modified species ranges this accumulated new information has allowed many of the planktonic foraminiferal bioevents of the cenozoic to be revised and the planktonic foraminiferal calibrations to be reassessed we incorporate these developments and amendments into the existing biostratigraphic zonal scheme in this paper we present an amended low latitude tropical and subtropical cenozoic planktonic foraminiferal zonation we compile 187 revised calibrations of planktonic foraminiferal bioevents from multiple sources for the cenozoic and have incorporated these recalibrations into a revised cenozoic planktonic foraminiferal biochronology we review and synthesize these calibrations to both the geomagnetic polarity time scale gpts of the cenozoic and astronomical time scale ats of the neogene and late paleogene on the whole these recalibrations are consistent with the previous work however in some cases they have led to major adjustments to the duration of biochrons recalibrations of the early middle eocene first appearance datums of globigerinatheka kugleri hantkenina singanoae guembelitrioides nuttalli and turborotalia frontosa have resulted in large changes in the durations of biochrons e7 e8 and e9 we have introduced upper oligocene zone o7 utilizing the biostratigraphic utility of paragloborotalia pseudokugleri for the neogene period major revisions are applied to the fohsellid lineage of the middle miocene and we have modified the criteria for recognition of zones m7 m8 and m9 with additional adjustments regarding the globigerinatella lineage to zones m2 and m3 the revised and recalibrated datums provide a major advance in biochronologic resolution and a template for future progress of the cenozoic time scale

cyclicity in the middle eocene cayraz carbonate formation haymana basin central anatolia turkey abstract the haymana basin in central anatolia turkey developed on a fore arc accretionary wedge during the late cretaceous and the middle eocene turbidite deposits fill the center of the basin and grade northwestward into shallow marine clastics and carbonates which in turn pass into lacustrine and fluvial deposits toward the margin the middle eocene cayraz formation represents the youngest paleotectonic unit of the haymana basin it is composed of two shelf systems ss each formed by a package of nummulitic banks and intervening calcareous mudstones 150 250 m thick overlying 70 100 m thick monotonous mudstones within each of the two shelf systems two orders of coarsening upward and shallowing upward sequences are recognized the smaller order sequences 3 10 m thick are termed basic units bu four types of basic units have been distinguished these are made up of either calcareous mudstone overlain by a nummulitic bank or silty mudstone overlain by sandy to conglomeratic beds each basic unit represents a specific depositional environment ranging from quiet lagoon or open marine to more energetic bank or sandy bar basic units are vertically associated to form three types of 15 35 m thick basic sequences bs which represent the time and space evolution of the shelf systems owing to their small scale their lateral association and the condensed nature of their bounding surfaces basic units are considered to be allocyclic transgressive regressive cycles tuned to milankovitch bands at the scale of basic sequences bs and shelf systems ss the lateral and vertical distribution of the sequences and the presence of onlap structures strongly suggest sea level changes the sequential organization thicknesses of basic units and basic sequences and an estimated sedimentation rate favour sea level changes controlled by milankovitch climatic cycles amalgamation or condensation of basic units in basic sequences and the existence of locally accentuated onlaps suggest a coupled effect of discontinuous subsidence

deposition of the uppermost cambrian croixan jordan sandstone and the nature of the cambrian ordovician boundary in the upper mississippi valley the jordan sandstone of late cambrian croixan age is well known as one of several cratonic sheet sandstones in the upper mississippi valley that are part of the classic paleozoic orthoquartzite carbonate suite evidence that the jordan is an entirely marine regressive sequence rather than transgressive as commonly assumed provides new insight into the origin of cratonic sheet sandstones the lower half of the jordan sandstone is composed of two intercalated lithofacies 1 extensively burrowed very fine grained sand stone interbedded with hummocky cross stratified beds deposited on the offshore shelf and 2 fine grained burrowed cross stratified sandstone deposited on the lower shoreface during storms the upper half of the jordan consists of medium to coarse grained sand stone deposited on the upper shoreface by tidal and storm generated currents this lithofacies is characterized by abundant scour surfaces tidal inlet fills and very large angular intra clasts of sandstone derived from incised beach rock on the foreshore lithofacies associations demonstrate that the jordan sandstone is a regressive sequence deposited as part of a shoreline system that prograded across the hollandale embayment a shallow depression on the cratonic shelf in the upper mississippi valley region progradation was interrupted by transgressive episodes recorded as local tongues of offshore deposits that disconformably overlie shoreface deposits this sedimentologic model contributes to the evaluation of depositional controls in late cambrian time and to solving some long standing enigmas associated with cratonic sheet sandstones contrary to the long held view that the cambrian ordovician boundary is conformable in this region sedimentologic evidence indicates that a regional unconformity separates the jordan sandstone from the early ordovician oneota dolomite deep incision into the lowest jordan lithofacies occurred near the transcontinental arch on the western margin of the embayment and near the wisconsin arch on the eastern margin this differential erosion marks the earliest known tectonic up lift of the basin9s margins relative to the center

assessing the impact of serwis mine tailings site on farmers wells using element and isotope signatures holy cross mountains south central poland this paper presents the results of a geochemical and isotopic study of technogenic soils and acid pool waters in the abandoned mine tailings pile and its potential impact on the adjacent farmers wells at the village of serwis south central poland the acid tailings pools showed strong trace element and ree signals these acid pools were featured by the predominance of medium rare earth elements mree with a strong positive gd anomaly the technogenic soils also revealed a mree roof shaped pattern but with distinct positive excursions in gd sm eu and ce the 34s so42 signatures of acid pool waters mean of 1 3 were close to those of soils and pyrite means of 2 3 and 3 2 respectively the waters of four farmers wells exhibited nearly the same 34s so42 values 0 7 4 0 as the nearby acid pool waters 0 3 3 1 the similar 34s isotope signatures combined with the highest contents of dissolved so42 181 577 mg l in these wells suggest that the tailings pile is a potential source of so42 derived from pyrite weathering this relationship may also be evidenced by a spatial site variable dendrogram that groups these four wells into one cluster at the linkage distance dlink dmax 100 53

cambrian chronostratigraphy current state and future plans abstract important steps have been made by the international subcommission on cambrian stratigraphy iscs toward global chronostratigraphic subdivision of the cambrian the consensus of opinion is that the system should be subdivided into four series representing subequal spans of time the lower two series will correspond approximately to the traditional lower cambrian the third series will correspond approximately to the traditional middle cambrian and the fourth series corresponds approximately to the traditional upper cambrian the fourth series called the furongian series was ratified by the international commission on stratigraphy ics and the international union of geological sciences iugs in 2003 selection of horizons representing evolutionary events that can be correlated on a global scale and which can be used as stage or series boundaries is much more difficult for the lower two series intervals of the cambrian than it is for the upper two series intervals of the cambrian the most practical concept for subdividing the system into stages involves the establishment of two stages each for the first and second series and the establishment of three stages each for the third and fourth series the lowermost stage of the furongian called the paibian stage has been ratified by the ics and the iugs

combining high resolution vertical gradients and sequence stratigraphy to delineate hydrogeologic units for a contaminated sedimentary rock aquifer system summary hydrogeologic units hgus representing subsurface contrasts in hydraulic conductivity form the basis for all conceptual and numerical models of groundwater flow however conventionally delineation of these units relies heavily on data sets indirect with respect to hydraulic properties here we use the spatial and temporal characteristics of the vertical component of hydraulic gradient i e vertical gradient as the primary line of evidence for delineating hgus for cambrian ordovician sedimentary rocks at a site in dane county wisconsin the site includes a 16 km2 area encompassing a 3 km long mixed organic contaminants plume the vertical gradients are derived from hydraulic head profiles obtained using high resolution westbay multilevel systems installed at 7 locations along two orthogonal 4 km long cross sections and monitoring to depths between 90 and 146 m with an average of 3 4 monitoring zones per 10 m these vertical gradient cross sections reveal 11 laterally extensive hgus with contrasting vertical hydraulic conductivity kv the position and thickness of the kv contrasts are consistently associated with sequence stratigraphic features maximum flooding intervals and sequence boundaries distinguished at the site using cores and borehole geophysical logs the same sequence stratigraphic features are also traceable across much of the cambrian ordovician aquifer system of the midwest us the vertical gradients and sequence stratigraphy were arrived at independently and when combined provide a hydraulically calibrated sequence stratigraphic framework for the site this framework provides increased confidence in the precise delineation and description of the nature of hgu contacts in each borehole reduced uncertainty in interpolation of the hgus between boreholes and some capability to predict hgu boundaries and thickness in offsite areas where high resolution hydraulic data sets are not available consequently this hgu conceptual model will serve as a better basis for numerical simulations of groundwater flow and contaminant transport needed for continued risk assessment and to evaluate potential remedial technologies for the site more broadly the association between kv contrasts and sequence stratigraphy demonstrated at this site provides valuable insight into the relationship between geology and hydraulic contrasts that can be transferred to other areas of the upper midwest us and perhaps elsewhere to strata deposited in similar settings

geochemistry and biogeochemistry of rare earth elements in a surface environment soil and plant in south china plants and soils derived from different kinds of parent materials in south china were collected for analyses of rare earth elements rees by inductively coupled plasma mass spectrometry icp ms the distribution patterns and transportation characteristics of rees in the soil plant system were studied the results show that geochemical characteristics of rees depend on the types of soils soils derived from granite being the highest in ree concentration in a soil profile ree concentrations are higher in b and c horizons than those in a horizon with eu negative anomaly and ce positive anomaly plants of different genera growing in the same sampling site have quite similar ree distribution pattern but plants of the same genera growing in different soils show considerable variation in characteristics of rees the patterns of the different parts of plant resemble each other but the slope of the patterns becomes different rees have fractionated when they were transported and migrated from soil to plant root stem and leaf revealing that heavy rees are relatively less available rees distributions in plants are influenced by the soil they grow in and also characterized by their individual biogeochemical characteristics biological absorption coefficients indicate difference of ree absorption capacity of plants

dominants and accumulation of rare earth elements in sediments derived from riparian and depressional marshes the rare earth elements rees in the sediments of the xianghai wetlands were measured by inductively coupled plasma spectrometry the rees accumulation rates in two sedimentation cores derived from the riparian and depressional marshes were determined by 210pb method the results showed that rees concentrations in the xianghai wetland sediments rees 116 mg kg 1 were lower than the corresponding values in chinese soils 181 mg kg 1 and river sediments rees 158 191 mg kg 1 under alkaline conditions with ph 8 2 10 3 the light rees were more enriched than the heavy rees cerium is the predominant element and accounts for 30 33 of the total rees rees in the depressional marsh sediments were relatively high rees 127 vs 104 mg kg 1 especially light rees contents a significantly positive correlation was found between the neighboring elements except pr and dy the different types of vertical distribution of rees between the riparian and the depressional marsh can partly result from long term differing hydrological regimes generally depressional marsh had accumulated much more rees than riparian marsh the mean accumulation rates of rees 102 98 vs 48 89 g cm 2 year 1

the late cambrian spice δ13c event and the sauk ii sauk iii regression new evidence from laurentian basins in utah iowa and newfoundland carbon isotope data from upper cambrian sections in three laurentian basins in northern utah central iowa and western newfoundland record a large positive d 13 c excursion spice event of up to 1 5 peak d 13 c ratios are well dated by trilobite collections to the middle of the steptoean stage dunderbergia zone and occur during maximum regression associated with formation of the sauk ii sauk iii subsequence boundary on the north american craton max imum regression was marked by an influx of quartz sand into carbon ate platform settings in all three widely separated basins in northern utah this quartz sand formed a thick sequence known as the worm creek quartzite which marks a conspicuous interruption of carbonate deposition during the middle to late cambrian in the region in west ern newfoundland the thickness of the quartz sand unit is much re duced but still marks a brief shutdown of the carbonate factory that is unique to the cambrian shelf succession of the area in the central iowa area of the cratonic interior an upward shallowing carbonate succession culminates in cross stratified trilobite grainstones at the peak of the spice in dunderbergia zone time and the lowest point on the relative sea level curve is associated with the occurrence of coarse quartz sand derived from the encroaching shoreface although it is difficult to determine precisely the departure from baseline d 13 c that marks the beginning of the spice excursion in the stratigraphic successions analyzed our results are consistent with a rise and subsequent fall in d 13 c tracking a major regressive transgressive event recorded across northern laurentia the correlation of a major d 13 c excursion with regression is similar to that described for the late ordovician for which the pattern has been attributed to either in creased carbonate relative to terrigenous weathering rates as ice sheets covered up organic matter containing silicates at high latitudes or high productivity and organic carbon burial driven by oceanic overturn the lack of known steptoean age ice sheets that could have affected the ratio of carbonate to silicate weathering rates suggests that organic carbon burial was the likely cause of the spice event we suggest that increased weathering and erosion rates during relative sea level fall sauk ii iii increased the burial fraction of organic carbon in an expanded region of fine grained siliciclastic deposits in shelf and upper slope environments during the steptoean

upper cambrian carbonate platform evolution elvinia and taenicephalus zones pterocephaliid ptychaspid biomere boundary northwestern wyoming abstract the pterocephaliid ptychaspid biomere boundary is an upper cambrian extinction horizon that can be used to correlate mixed carbonate siliciclastic strata in northwestern wyoming the biomere boundary is defined by the change between the elvinia and taenicephalus zones of the standard north american trilobite zonation it is also signaled chemostratigraphically by a positive trend in carbon isotope ratios thus both biostratigraphic horizons and carbon isotope data are used to constrain the position of the biomere boundary in northwestern wyoming study of 21 stratigraphic sections reveals the presence of distinct facies belts for the middle and upper elvinia zone and lower taenicephalus zone these are interpreted to reflect deposition in three distinct paleoenvironments 1 oolitic shoal 2 intrashelf basin and 3 inner platform margin following a major hiatus in sedimentation in wyoming during much of pterocephaliid biomere time a healthy shallow water carbonate factory was reestablished during elvinia zone time this produced abundant deposits of oolitic and skeletal packstone in the shoal environment and an areally extensive thrombolite boundstone facies in the intrashelf basin setting approximately coincident with the biomere boundary extinction event irvingella major time ooid production was terminated and the thrombolites were drowned the correlation of this major change in the pattern of sedimentation allows for the recognition of parts of two depositional sequences in the study area this drowning event sequence boundary may also be coeval with the accumulation of transported shallow water carbonate deposits in an inner platform margin environment during early taenicephalus zone time sedimentation rates were apparently reduced and the entire study area is marked by thin concentrations of trilobite and brachiopod shells the nonskeletal carbonate factory was never reestablished in the former shoal environment where thick successions of homogeneous lime mud accumulated during the rest of taenicephalus zone time flat pebble conglomerate and shale accumulated in the storm influenced intrashelf basin during this time sea level change and changes in seawater chemistry likely both played roles in the drowning event across the elvinia taenicephalus boundary a positive trend in carbon isotope values across the pterocephaliid ptychaspid biomere boundary is observed in the six sections analyzed this is consistent with previous studies that indicated that the mass extinction occurs within a regional shift towards positive values and this may reflect the development of low oxygen conditions on the shelf the global significance of these isotopic trends changes in relative sea level and the mass extinction has not been confirmed although recent study of the extinction event at the base of the pterocephaliid biomere has revealed a similar trend towards positive carbon isotope values that is worldwide

origin of a classic cratonic sheet sandstone stratigraphy across the sauk ii sauk iii boundary in the upper mississippi valley the origin of cratonic sheet sandstones of proterozoic and early paleozoic age has been a long standing problem for sedimentologists lower paleozoic strata in the upper mississippi valley are best known for several such sandstone bodies the regional depositional histories of which are poorly understood we have combined outcrop and subsurface data from six states to place the upper cambrian wonewoc ironton and galesville sandstone in a well constrained stratigraphic framework across thousands of square kilometers this framework makes it possible for the first time to construct a regional scale depositional model that explains the origin of this and other cratonic sheet sandstones the wonewoc sandstone although mapped as a single contiguous sheet is a stratigraphically complex unit that was deposited during three distinct conditions of relative sea level that span parts of four trilobite zones during a relative highstand of sea level in crepicephalus zone time quartzose sandstone lithofacies aggraded more or less vertically in nearshore marine and terrestrial environments across much of the present day outcrop belt around the wisconsin arch at the same time finer grained feldspathic sandstone siltstone and shale aggraded in deeper water immediately seaward of the quartzose sand and shale and carbonate sediment accumulated in the most distal areas during aphelaspis and dunderbergia zones time a relative fall in sea level led to the dispersal of quartzose sand into a basinward tapering sheet like body across much of the upper mississippi valley during early elvinia zone time a major transgression led to deposition of a second sheet sandstone that is generally similar to the underlying regressive sheet the results of this investigation also demonstrate how subtle sequence bounding unconformities may be recognized in mature cratonic siliciclastics we place the sauk ii sauk iii subsequence boundary at the base of the coarsest bed in the wonewoc sandstone a lag developed through erosion that occurred during the regional regressive transgressive event that spanned aphelaspis to early elvinia zones time such sequence bounding unconformities are difficult to recognize where they are contained within coarse siliciclastics of the upper mississippi valley because they separate strata that are texturally and mineralogically similar and because erosion occurred on a loose sandy substrate along a low uniform gradient and in a nonvegetated terrestrial environment furthermore the ultramature mineral composition of the exposed substrate is resistant to the development of a recognizable weathering profile the well known sheet geometry of the wonewoc and other units of lower paleozoic sandstone of this area is not dependent on atypical terrestrial depositional conditions conducive to the widespread distribution of sand as commonly believed sand was spread into a sheet dominantly within the marine realm in a manner similar to that inferred for many better known sandstone bodies deposited in the north american cretaceous western interior seaway and tertiary gulf of mexico the laterally extensive thin character of the upper mississippi valley sandstone bodies compared to these other sandstone bodies simply reflects deposition of a continuously abundant supply of sand on a relatively stable nearly flat basin of slow uniform subsidence during changes in sea level the dearth of shale in this and other cratonic sandstones can be indirectly attributed to the same controls which led to an uncommonly low preservation potential for fairweather deposits on the shoreface

eolian action and the distribution of cambrian shales in north america prolonged eolian action on the barren prevegetation craton provides a better explanation for the absence of shale in the cambrian and lower ordovician orthoquartzite carbonate suite of east central and arctic north america than does marine bypassing it is hypothesized that paleo trade winds transported much of the missing silt and clay to the southern and western united states and southwestern canada while the remainder diffused radially off the craton under the influence of variably directed storm winds the distribution of shale in the sauk sequence supports this and indicates that the orthoquartzite carbonate suite of upwind regions is replaced by a shale carbonate suite in downwind areas

detailed hydraulic head profiles as essential data for defining hydrogeologic units in layered fractured sedimentary rock this paper describes a study in southern wisconsin where vertical hydraulic head profiles measured in exceptional detail provided the key data for defining hydrogeologic units hgus in a layered sequence of sandstone siltstone shale and dolostone the most important data were obtained from corehole mp 6 which was cored 131 m into bedrock and instrumented using a westbay multilevel system with 36 depth discrete monitoring intervals the resulting head profile is consistant over time and shows eight distinct inflections in hydraulic head several of the inflections occur between adjacent permeable units and are likely due to poor vertical connectivity of fracture sets rather than distinct lower permeability layers or aquitards in the conventional sense no other type of data was capable of identifying the position of such distinct hydrogeologic features these zones of abrupt head loss provide the primary dataset for delineation of eleven hgus at mp 6 and are supported by less detailed head profiles at other locations although the detailed head profiles are essential core logs and geophysical logs from other boreholes are nessessary to fully establish the lateral continuity of the hgus

larger foraminiferal and coralline algal facies in an upper eocene storm influenced shallow water carbonate platform colli berici north eastern italy abstract facies analysis of priabonian shallow water carbonate successions in the outcrops near mossano eastern colli berici north eastern italy and the subsequent integration of palaeoecological data have been used to produce a detailed palaeoenvironmental model the facies distribution and the processes which controlled the larger benthic foraminiferal and coralline algal assemblages in the study priabonian storm influenced carbonate ramp are discussed in detail in the middle ramp trough cross bedded small nummulites and rhodolith packstones pass laterally into coralline algal crust wackestones these rhodoliths exhibit two well differentiated growth phases the first occurring during low water energy periods followed by a second developed during high energy events during which they were reworked and partially destroyed these facies pass laterally into orthophragminid rudstones and packstones characterised by orthophragminid tests and channel structures the latter were formed by storm induced return currents which swept the middle ramp creating distal middle ramp channel structures further toward the distal part of the middle ramp the return currents decreased in energy and discharged nutrients allowing the coralline crustose pavement to develop this is characterised by rhodoliths typically discoidal in shape up to 10 cm in diameter with a loose inner arrangement consisting of encrusting to foliose growth forms the occurrence of the channel structures in orthophragminid rudstones and in the coralline crustose pavement appears to be unique in upper eocene carbonate ramp depositional systems during the erosive events associated with the return currents these shallow water carbonates were unlithified or only weakly lithified and were therefore easily transported into deeper water ramp settings the model suggests that the significant changes of the middle ramp benthic communities with depth could have formed at least in part by offshore return currents which played an important role in both controlling substrates and in supplying nutrients

ecology of extant nummulitids and other larger benthic foraminifera applications in palaeoenvironmental analysis abstract larger benthic foraminifera lbf are important contributors to modern and ancient tropical shallow marine sediments over the past 30 years a substantial body of literature has built up on the ecology of modern lbf especially in terms of their environmentally sensitive depth distribution reproductive strategy and morphology and the symbiotic relationship between many larger foraminifera and photosynthetic algae over the same period the extinct genus nummulites which is abundant in eocene sediments of southern europe north africa and the arabian peninsula has increasingly been studied principally because significant volumes of hydrocarbons have been discovered reservoired within nummulitic limestones offshore tunisia and libya the modern ecological studies of lbf provide a powerful tool with which to develop palaeoecological models for fossil nummulites and other symbiont bearing larger foraminifera in the rock record

the middle eocene seeb formation of oman an investigation of acyclicity stratigraphic completeness and accumulation rates in shallow marine carbonate settings abstract the middle eocene seeb formation represents deposition on one of the earliest modern style carbonate platforms i e influenced by seagrasses and mangroves and presents an opportunity to explore controls on the preservation of cenozoic carbonate lithofacies in the study area the seeb fm is dominated by an anomalously thick approximately 250 m and uniform package of shallow marine platform interior sediments these nodular indistinctly bedded shallow subtidal sediments display no evidence for relative sea level change such as subaerial exposure features and lack the shallowing upwards cyclothems that have characterized carbonate sediments deposited in platform interior settings throughout much of the rock record particularly during greenhouse periods we conclude that this is a consequence of thorough bio retexturing of the sediment by burrowing organisms and the roots of marine vegetation which destroyed primary fabrics facies diversity evidence for cyclicity and missing time horizons such as cycle bounding exposure surfaces it seems possible that the remarkable thickness of apparently acyclic seeb fm sediment that built up may reflect increased bio disturbance of the shallow marine environment following the late cretaceous expansion of seagrasses and mangroves a similar lack of peritidal cyclothems may be common to many cenozoic shallow marine carbonate deposits missing time horizons in limestones reflecting erosion or nondeposition have been identified by some authors to explain discrepancies between low calculated accumulation rates of ancient sediments and higher rates measured in comparable modern environments however our studies of the seeb fm suggest that the significance of such missing time horizons in ancient sediments may have been overstated and that apparent differences between modern and ancient accumulation rates are a consequence of the extrapolation of unrepresentative localized high rates of modern sediment production to large platform scale areas our study reinforces the idea that modern sediment production and accumulation rates may be much lower than previously thought because they are typically measured in highly productive areas such as seagrass beds and do not take into account the highly variable nature of carbonate production storage erosion and destruction across platforms therefore far less missing time needs to be inferred for ancient sediments to account for any imbalance between modern and ancient sediment accumulation rates

carbonate sedimentation in an extensional active margin cretaceous history of the haymana region pontides the haymana region in central anatolia is located in the southern part of the pontides close to the izmir ankara suture during the cretaceous the region formed part of the south facing active margin of the eurasia the area preserves a nearly complete record of the cretaceous system shallow marine carbonates of earliest cretaceous age are overlain by a 700 m thick cretaceous sequence dominated by deep marine limestones three unconformity bounded pelagic carbonate sequences of berriasian albian cenomanian and turonian santonian ages are recognized each depositional sequence is preceded by a period of tilting and submarine erosion during the berriasian early albian and late cenomanian which corresponds to phases of local extension in the active continental margin carbonate breccias mark the base of the sequences and each carbonate sequence steps down on older units the deep marine carbonate deposition ended in the late santonian followed by tilting erosion and folding during the campanian deposition of thick siliciclastic turbidites started in the late campanian and continued into the tertiary unlike most forearc basins the haymana region was a site of deep marine carbonate deposition until the campanian this was because the pontide arc was extensional and the volcanic detritus was trapped in the intra arc basins and did not reach the forearc or the trench the extensional nature of the arc is also shown by the opening of the black sea as a backarc basin in the turonian santonian the carbonate sedimentation in an active margin is characterized by synsedimentary vertical displacements which results in submarine erosion carbonate breccias and in the lateral discontinuity of the sequences and differs from blanket like carbonate deposition in the passive margins

recognizing artifactually generated coordinated stasis implications of numerical models and strategies for field tests abstract a null model that generates the first and last occurrences of species through time in a single stratigraphic section predicts several patterns startlingly similar to those described as coordinated stasis the model is able to produce these patterns by assuming stochastically constant extinction and origination rates a gaussian form of facies control with respect to water depth and cyclically varying water depths in accord with sequence stratigraphy the model predicts that highstand and lowstand systems tracts will be characterized by faunal tracking with only minor amounts of faunal turnover sequence boundaries and flooding surfaces within the transgressive systems tract will be characterized by elevated rates of faunal turnover these pulses of faunal turnover will exhibit ecological selectivity in terms of the preferred depths facies tolerances and abundance of species where outcrop patterns of first and last occurrences match these predictions biologically driven or environmentally driven coordinated stasis may not be distinguishable from stratigraphic artifact however pulses of faunal turnover that occur within highstand and lowstand systems tracts are likely to be real turnover events multiple outcrop studies that span a significant distance along paleoslope are necessary to disprove artifactual turnover that occurs at a sequence boundary or within a transgressive systems tract

middle eocene nummulites and their offshore re deposition a case study from the middle eocene of the venetian area northeastern italy abstract the middle eocene calcari nummulitici formation from northeastern italy venetian area represents a shallow marine carbonate ramp developed on the northern tethyan margin in the monti berici area its main components are larger foraminifera and coralline red algal communities that constitute thick carbonate sedimentary successions middle ramp and proximal outer ramp environments are recognized using component relationships biofacies and sedimentary features the middle ramp is characterized by larger flattened lenticular nummulites on palaeohighs between which rhodoliths formed larger nummulites palaeohighs containing nummulites millecaput nummulites crassus nummulites discorbinus and nummulites cf gizehensis developed more basin wards the following relatively quiet environments of basin wards of the palaeohighs represent areas of maximum carbonate production the transition between the distal middle and the proximal outer ramp settings is marked in the study area by a large erosional surface which is interpreted to have been formed as a result of an erosive channel body filled in by deposits re sedimented from shallower depths these off shore re sedimented channelized deposits ascribed to the shallow benthic zone sbz 15 lying on hemipelagic marls planktonic foraminiferal zone e9 p11 allow for a biostratigraphic correlation to the late lutetian the studied deposits represented by packstone to rudstones were displaced whilst still unlithified the lutetian bartonian regression along with the local tectonic activity promoted the production of a high amount of biogenic shallow water carbonates mainly produced in the mossano middle ramp settings these prograded towards the basinal areas with high sedimentation rate of carbonate deposits characterized by the larger nummulites rudstones such high amounts of sediment led to sediment instability which potentially could be mobilized either by return currents due to occasional major storms or by earthquakes induced by tectonic activity these will have led to the offshore re deposition of the nummulites sediments into deeper water setting via the observed channels since potential migration pathways are short such distal re sedimented channel filled material surrounded by hemipelagic marls is optimally placed for the formation of potential subsurface oil reservoirs

fallen arches dispelling myths concerning cambrian and ordovician paleogeography of the rocky mountain region high resolution sedimentologic biostratigraphic and stable isotope data from numerous measured sections across colorado reveal a complex architecture for lower paleozoic strata in the central cordilleran region a lack of precise age control in previous studies had resulted in misidentification and miscorrelation of units between separate ranges corrections of these errors made possible by our improved data set indicate the following depositional history the quartz rich sandstone of the sawatch formation was deposited during onlap of the precambrian erosion surface in the early late cambrian the overlying dotsero formation a regionally extensive carbonate and shale rich succession records blanket like deposition with only minor facies changes across the state an extremely widespread meter scale stromatolite bed the clinetop bed caps the dotsero formation in most areas however a latest cambrian erosional episode removed 9 11 m of the upper dotsero formation including the clinetop bed from just east of the homestake shear zone in the sawatch range eastward to the mosquito range the overlying manitou formation differs in character and thus in member stratigraphy on the east vs west sides of the state these differences were previously interpreted as the result of deposition on either side of a basement high that existed within the central colorado embayment or colorado sag a region of major breaching across the transcontinental arch this paleogeographic reconstruction is shown herein to be an artifact of miscorrelation biostratigraphic data show that the northwestern members of the manitou formation are older than the members exposed in the southeastern part of the state and that there is little or no overlap in age between the two areas this circumstance is the result of 1 removal of older manitou formation strata in the southeast by an unconformity developed during the rossodus manitouensis conodont zone and 2 erosion of younger manitou strata in central and western colorado along middle ordovician and devonian unconformities deciphering these complex stratal geometries has led to invalidation of long held views on western laurentian paleogeography during the cambrian and earliest ordovician specifically the existence of the colorado sag and a northeast trending high within the sag that controlled depositional patterns on either side the mid rossodus uplift and resultant unconformity eliminated any and all upper cambrian and lower ordovician deposits in southern colorado and northern new mexico and thus their absence should not be misconstrued as evidence for earlier nondeposition in this region lithofacies distribution patterns and isopach maps provide no evidence that highlands of the transcontinental arch existed in colorado prior to the mid rossodus age uplift event in fact regional reconstructions of earliest paleozoic paleogeography along the entire length of the purported transcontinental arch should be reevaluated with similarly precise biostratigraphic data to reconsider all potential causes for missing strata and to eliminate topographic elements not supported by multiple stratigraphic techniques this study illustrates how seriously paleogeographic reconstructions can be biased by the presumption that missing strata represent periods of nondeposition rather than subsequent episodes of erosion particularly in thin cratonic successions where stratigraphic gaps are common and often inconspicuous

sequence stratigraphy of the upper cambrian furongian jiangshanian and sunwaptan tunnel city group upper mississippi valley transgressing assumptions of cratonic flooding abstract new data from detailed measured sections permit comprehensive analysis of the sequence framework of the furongian upper cambrian jiangshanian and sunwaptan stages tunnel city group lone rock formation and mazomanie formation of wisconsin and minnesota the sequence stratigraphic architecture of the lower part of the sunwaptan stage at the base of the tunnel city group at the contact between the wonewoc formation and lone rock formation records the first part of complex polyphase flooding sauk iii of the laurentian craton at a scale smaller than most events recorded by global sea level curves flat pebble conglomerate and glauconite document transgressive ravinement and development of a condensed section when creation of accommodation exceeded its consumption by sedimentation thinly bedded fossiliferous sandstone represents the most distal setting during earliest highstand subsequent deposition of sandstone characterized by hummocky or trough cross stratification records progradational pulses of shallower storm and wave dominated environments across the craton before final flooding of sauk iii commenced with carbonate deposition during the middle part of the sunwaptan stage comparison of early sunwaptan flooding of the inner laurentian craton to published interpretations from other parts of north america suggests that sauk iii was not a single long term accommodation event as previously proposed

interstratal dewatering origin for polygonal patterns of sand filled cracks a case study from late proterozoic metasediments of islay scotland sand filled cracks from the lower fine grained quartzite of dalradian late proterozoic age on the island of islay western scotland may be divided into two main types both of which form orthogonal and non orthogonal closed patterns on bedding surfaces type 1 cracks are short and lenticular in cross section contain sand which had been injected downwards and are found on the bottoms of cross laminated sandstone beds type 2 cracks cut several beds and preserve evidence of upward flow of water saturated sand both types of crack developed through the interstratal intrusion of water saturated sand into shrinkage cracks in mud or muddy sand not as previously thought as a result of sub aerial desiccation or sub aqueous cracking of the sediment surface synaeresis these cracks likely resulted from layer parallel contraction caused by compaction of mudstone layers during burial seismic shock may have provided the trigger for the preferential development of polygonal crack patterns in these layers instead of the more usual small scale dewatering structures from a detailed comparison with published descriptions of filled cracks from a number of different geological environments it is concluded that interstratal cracking is a mechanism which rivals sub aerial desiccation in importance and is more common in the geological record than is currently realized

large scale natural gradient tracer test in sand and gravel cape cod massachusetts 1 experimental design and observed tracer movement a large scale natural gradient tracer experiment was conducted on cape cod massachusetts to examine the transport and dispersion of solutes in a sand and gravel aquifer the nonreactive tracer bromide and the reactive tracers lithium and molybdate were injected as a pulse in july 1985 and monitored in three dimensions as they moved as far as 280 m down gradient through an array of multilevel samplers the bromide cloud moved horizontally at a rate of 0 42 m per day it also moved downward about 4 m because of density induced sinking early in the test and accretion of areal recharge from precipitation after 200 m of transport the bromide cloud had spread more than 80 m in the direction of flow but was only 14 m wide and 4 6 m thick the lithium and molybdate clouds followed the same path as the bromide cloud but their rates of movement were retarded about 50 relative to bromide movement because of sorption onto the sediments

evidence for temporally changing mechanical stratigraphy and effects on joint network architecture previous studies of jointing in sedimentary rocks have shown that joint network archi tecture is controlled by mechanical stratigraphy which is described by 1 the thickness and rigidity of stratigraphic units and 2 the nature of interfaces between beds using joint pattern to infer rigidity contrast between beds is complicated by the possibility that material properties of the beds may change between fracturing events observation of both an early bed contained joint set and a differently oriented late throughgoing joint set in the same beds of growth strata in the oliana anticline in the spanish pyrenees may reflect changing mechanical properties i e via diagenesis during the folding process using a schmidt hammer we assess the rigidity contrast between the individual units and show that the present day contrast is not great enough to terminate joints at interfaces this result is consistent with an interpretation that the late stage throughgoing joints formed in strata with conditions similar to those of the present day and that the early bed contained joints formed when the rigidity contrast between beds was significantly greater than that of the present day for example differential diagenesis rates between layers of differing grain size would produce temporally changing mechanical stratigraphy we propose that changes in mechanical stratigraphy may have previously been unrec ognized in other stratigraphic sections and that these changes affect joint network archi tecture and subsequent fluid flow pathways

mixed siliciclastic carbonate upward deepening cycles of the upper cambrian inner detrital belt of laurentia abstract high resolution sedimentological and biostratigraphic data recently recovered from upper cambrian strata in the northern rocky mountain and central appalachian regions reveal that meter scale cycles of very different character developed synchronously during deposition of the basal subzones of the ibexian series in both the carbonate facies belt and the distal part of the inner detrital mixed siliciclastic carbonate facies belt of the laurentian paleocontinent a typical mixed siliciclastic carbonate cycle in the snowy range formation of wyoming and montana consists of the following lithofacies in ascending order shale shale with very thin grainstone interbeds grainstone with subordinate thin shale interbeds flat pebble conglomerate and in some cycles thrombolitic bioherms internal transitions between the constituent lithofacies are mostly gradational but cycle boundaries are sharp with shale directly overlying flat pebble conglomerate and or thrombolitic boundstone we postulate that these mixed siliciclastic carbonate cycles developed in response to different depositional dynamics than meter scale cycles developed in carbonate belt facies specifically cycles in the carbonate belt were produced largely by temporal variation in accommodation space and associated filling of that space through progradation of the carbonate system and aggradation to sea level in contrast cyclic deposition within the inner detrital belt was controlled by variations in terrigenous sediment input and resulting effects on carbonate productivity in this case enhanced delivery of siliciclastic mud by rivers was triggered by regression and or a shift to more humid climatic conditions an upward increase of carbonate in the main part of the cycles reflects enhanced carbonate production in response to the reduction of terrigenous clay supply during shoreline retreat widespread cementation of fine grainstone substrates led to deposition of extensive beds of flat pebble conglomerate possibly in association with elevated sea surface temperatures and enhanced storm intensity thrombolites formed at times of maximum transgression as microbial communities thrived in the absence of turbidity colonizing the irregular surfaces of flat pebble conglomerate beds we thus interpret these wholly subtidal cycles to record full changes in paleobathymetry with the bulk of the cycles recording upward deepening rather than shoaling associated with regression comparison with age equivalent shoaling cycles of the conococheague formation of the carbonate belt of the appalachian mountains highlights the different depositional dynamics in the mixed siliciclastic carbonate systems and underscores the peril in extrapolation of depositional models derived from carbonate systems to mixed systems regardless of age or paleogeographic setting