relation between depositional environment and the elemental composition of early diagenetic siderite early diagenetic siderites from marine and fresh water depositional environments are characterized by distinctive compositional trends siderite from fresh water environments is often relatively pure i e greater than 90 mol feco sub 3 and commonly attains end member composition siderite from marine environments however is always extremely impure and has extensive substitution of mg up to 41 mol and to a lesser extent ca up to 15 mol for fe in the siderite lattice in addition marine siderite generally contains less mn and has a higher mg ca ratio than fresh water siderite this compositional variation appears to result from differences in the chemistry of early marine and meteoric pore waters inasmuch as early marine pore waters generally have a higher mg sup 2 ca sup 2 ratio and contain less mn sup 2 and fe sup 2 and more ca sup 2 and mg sup 2 than meteoric waters

stable isotopic investigation of clay minerals and pedogenesis in an interfluve paleosol from the cenomanian dunvegan formation n e british columbia canada abstract mineralogical and stable hydrogen and oxygen isotopic compositions have been obtained for clay minerals comprising an interfluve paleosol clayhurst ch 2 from the early to middle cenomanian dunvegan formation british columbia canada this paleosol provides a special opportunity to determine the stable isotopic composition of early late cretaceous paleoprecipitation on the western coast of the western interior seaway at a very northerly paleolatitude 65 detrital kaolinite and illite and complex dioctahedral mixed layer clay minerals of pedogenic origin are abundant throughout the paleosol in the d values of 93 to 81 and 18 o values of 12 9 to 11 6 were generally obtained for the ancient soil water and hence paleoprecipitation for one thin interval near the top of the paleosol higher values are indicated for the ancient soil water these results may indicate processes arising from a westward transgression of the western interior seaway

basin scale diagenetic alteration of shoreface sandstones in the upper cretaceous spring canyon and aberdeen members blackhawk formation book cliffs utah abstract leached zones whitecaps and dolomite cement bodies are volumetrically and areally significant features in shoreface sandstones of the upper cretaceous spring canyon and aberdeen members blackhawk formation book cliffs utah quantitative spatial and stratigraphic data of their distribution together with petrography and geochemistry allow development of a model for their formation within a sequence stratigraphic framework leached zones up to 5 m thick and 15 km in lateral extent are present beneath coals capping parasequences concretionary dolomite cement is present in shoreface sandstones downdip of parasequence capping coals and associated whitecaps these concretions are up to 2 m thick and 6 m in length and are present for up to 7 km downdip of these coals petrographic and field data indicate an early diagenetic timing for whitecap and dolomite cement formation 13c data suggest carbonate derivation from detrital dolomite whereas 18o data suggest that cement precipitated from porewater with a significant meteoric component although later diagenetic re equilibration and recyrstallization cannot be rejected we propose that organic acid generation during early diagenesis of coals led to the leaching of detrital dolomite from underlying sandstones and the formation of whitecaps meteoric water flowed basinward in response to base level lowering and sequence boundary development in the upper part of the aberdeen member remobilizing dolomite into shoreface sandstones dolomite precipitation resulted from the mixing of these meteoric fluids with downdip marine pore fluids and the presence of detrital dolomite in the shoreface sandstones that acted as nucleation sites for dolomite precipitation the geometry and extent of dolomite cement in the spring canyon and aberdeen members is in marked contrast to the much greater spatial extent of such cement in low accommodation space settings such as the stratigraphically younger desert member blackhawk formation the relatively simple aggradational to progradational evolution of the spring canyon and aberdeen member parasequences with only minor sequence boundary development in its upper part resulted in spatially limited meteoric fluid input into shoreface sandstones this resulted in dolomite cementation of shoreface sandstones up to a maximum of 7 km downdip of leached zones in the desert member extensive meteoric fluid migration as a result of major sequence boundary development resulted in dolomite cementation of shoreface sandstones for over 25 km downdip of leached zones this highlights that the degree and extent of early fluid diagenesis can be significantly controlled by the nature of sequence development having clear implications for developing predictive models for porosity permeability evolution in sandstone reservoirs

polygenetic history of paleosols in middle upper pennsylvanian cyclothems of the illinois basin u s a part ii integrating geomorphology climate and glacioeustasy abstract distinct lateral and stratigraphic trends in paleosol morphology and clay mineralogy in conjunction with the stable isotope composition of sub millimeter scale spherulitic siderite sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian cyclic coal bearing strata of the illinois basin ib presented herein provide proxy records of middle late pennsylvanian equatorial terrestrial environments collectively these data provide a better understanding of the polygenetic history of ancient soils preserved in cyclic strata and indicate that low latitude pennsylvanian ib soil profiles were influenced by a combination of autogenic and allogenic controls lateral variations in paleosol morphology from the interior of the basin to the northern margin indicate that soil development was dominantly influenced by autogenic controls such as differences in local paleohydrology i e groundwater fluctuations and subsidence rates across the basin conversely allogenic controls i e glacioeustasy and climate are interpreted to be principally responsible for the preservation of features in gleyed protosols gleyed vertisols and gleyed calcic vertisols that occur in the interior of the ib these paleosols are characterized by a polygenetic development history that includes 1 an initial period of soil formation in well drained environments with seasonal wetting and drying of the profile followed by 2 a subsequent period of waterlogging and development of reducing conditions paleosols that lack evidence for extensive periods of waterlogging are restricted with the exception of two examples to the northern margin of the basin and they become abundant in the stratigraphic record near the middle upper pennsylvanian boundary uppermost desmoinesian the stratigraphic distribution of these paleosols in conjunction with a decrease in the relative abundance of kaolinite in the 2 m size fraction of ib paleosols near the desmoinesian missourian d m boundary is interpreted to reflect a shift in the overall low latitude regional climate to drier conditions the stable isotope compositions of sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian strata of the ib provide an additional proxy record of past equatorial terrestrial environments and are used to constrain the magnitude of paleoclimate change across the d m moscovian kasimovian boundary sphaerosiderite 18ov pdb and 13cv pdb values range from 3 6 to 0 5 and 12 8 to 3 2 respectively in particular sphaerosiderite 18o values from the b horizons of paleosols display an approximate 1 5 shift across the d m boundary this stratigraphically short isotopic shift occurs across the d m boundary on the order of one cyclothem 400 kyr and is followed by a subsequent shift on the order of one cyclothem back to more positive siderite 18o values the average 18ov smow and dv smow values of kaolinite isolated from the 0 2 m size fraction of a latest desmoinesian flint clay breccia are 21 0 and 46 5 these values correspond to a latest desmoinesian crystallization temperature of 27 2 c and a meteoric water 18ov smow value of 3 1 combination of sphaerosiderite 18o values and co occurring flint clay kaolinite d and 18o values suggest a possible warming of up to 6 c across the d m boundary corresponding to an approximate temperature change of siderite crystallization from 27 to 33 c this temperature increase in conjunction with distinct stratigraphic trends in the clay mineralogy and morphology of ib paleosols is consistent with previous paleoclimate interpretations and it suggests that low latitude pennsylvanian paleoclimate became drier and warmer across the d m boundary

telluric measurements and differential geomagnetic soundings in the rhinegraben period range 1 125 s summary in 1976 seven stations measuring the variations of the telluric and geomagnetic fields in the period range 1 125 s were operated in the southern part of the rhinegraben the study of the recordings shows that the telluric field is linearly polarized according to a direction perpendicular to that of the horizontal anomalous magnetic fields and that telluric and anomalous magnetic fields have the same time dependence the conducted currents responsible for the anomaly flow probably into the superficial conductive layer

contribution of the surficial effects on the low frequency magnetotelluric anomaly at the rheingraben area abstract the distortions in the low frequency plane wave electric field due to variations of the conductance values of the sedimentary cover are considered for the rheingraben area the results suggest that the main part of the observed low frequency magnetotelluric anomaly can be explained by these distortions

xas evidence for ni sequestration by siderite in a lateritic ni deposit from new caledonia mineralogical and spectroscopic analyses were conducted on a lateritic ni deposit from southern new caledonia results show that ni is incorporated in siderite feco3 found between 37 and 40 m depth in the laterite and saprolite units of the regolith sem edxs analyses of siderite rich samples indicate that a significant amount of nickel can be hosted by this crystalline phase 0 8 wt nio ni and fe k edge extended x ray absorption fine structure exafs spectroscopic analyses of the siderite rich samples from the regolith as well as comparison with synthetic ni bearing and ni free siderites demonstrate isomorphous substitution of ni2 for fe2 in the siderite structure linear combination fitting lcf of the ni k edge exafs data reveals that this ni bearing siderite species accounts for more than 90 of the total ni pool 1 wt nio in the siderite rich horizons of the regolith in addition lcf analysis of the exafs spectra indicates that goethite and serpentine are the major ni hosts in the upper horizons laterite and lower horizons saprolite of the regolith respectively formation of siderite an uncommon mineral species in such oxidized environments is attributed to the development of swampy conditions in organic rich lateritic materials that accumulated at the bottom of dolines these results thus show the importance of siderite as a host for nickel in lateritic ni deposits that have been affected by late hydromorphic and reducing conditions

high latitude meteoric δ18o compositions paleosol siderite in the middle cretaceous nanushuk formation north slope alaska siderite bearing pedogenic horizons of the nanushuk formation of the north slope alaska provide a critical high paleolatitude oxygen isotopic proxy record of paleoprecipitation supplying important empirical data needed for paleoclimatic reconstructions and models of greenhouse world precipitation rates siderite 18 o values were determined from four paleosol horizons in the national petroleum reserve alaska npr a grandstand 1 core and the values range between 17 6 and 14 3 peedee belemnite pdb with standard deviations generally less than 0 6 within individual horizons the 13 c values are much more variable ranging from 4 6 to 10 8 pdb a covariant 18 o versus 13 c trend in one horizon probably resulted from mixing between modified marine and meteoric phreatic fluids during siderite precipitation groundwater values calculated from siderite oxygen isotopic values and paleobotanical temperature estimates range from 23 0 to 19 5 standard mean ocean water smow minor element analyses show that the siderites are impure having enrichments in ca mg mn and sr minor element substitutions and mg fe and mg ca mg ratios also suggest the influence of marine fluids upon siderite precipitation the pedogenic horizons are characterized by gleyed colors rare root traces abundant siderite abundant organic matter rare clay and silty clay coatings and infillings some preservation of primary sedimentary stratification and a lack of ferruginous oxides and mottles the pedogenic features suggest that these were poorly drained reducing hydromorphic soils that developed in coal bearing delta plain facies and are similar to modern inceptisols model derived estimates of precipitation rates for the late albian of the north slope alaska 485 626 mm yr are consistent with precipitation rates necessary to maintain modern peat forming environments this information reinforces the mutual consistency between empirical paleotemperature estimates and isotope mass balance models of the hydrologic cycle and can be used in future global circulation modeling gcm experiments of greenhouse world climates to constrain high latitude precipitation rates in simulations of ancient worlds with decreased equator to pole temperature gradients

geophysical investigation of the temple of apollo hierapolis turkey abstract the ruins of hierapolis are located a few kilometres north of laodicea in the lycus valley western turkey this area is characterised by a large geothermic field that produces several hot water springs along tectonic structures fractures and faults inside hierapolis is the temple of apollo the principal deity of the city while the foundations of this temple go back to late hellenistic times the present remains of the upper structure are from the 3rd century ad next to it there is an underground chamber called the plutonion from which poisonous gases emerge this paper presents the results of a geophysical survey carried out to explore firstly the buried cavities or structures beneath the temple of apollo knowledge of which is important to understand whether the plutonion could be entered from the inside of the temple for completing the sacrifices secondly to contribute to the ongoing evaluation of ground penetrating radar gpr and electrical resistivity tomography ert as tools for research into subsurface archaeological features voids walls etc two dimensional ert imaging was used to detect the presence of an active normal fault passing under the temple of apollo as shown by geological geomorphological and archaeoseismological observations the resistivity profiles reveal the presence of conductive material clay covering the archaeological structures the presence of active normal faults is indicated by the displacement of the bedrock and the conductive material on top of it three dimensional gpr imaging was used to detect man made structures located under the temple of apollo the results of the two survey methods applied were compared assessing the relative merits and demerits of each technique their combined use is discussed in terms of providing enhanced views that are more informative than a single method

polygenetic history of paleosols in middle upper pennsylvanian cyclothems of the illinois basin u s a part i characterization of paleosol types and interpretation of pedogenic processes abstract the morphology mineralogy and stratigraphic and lateral distribution of paleosols in pennsylvanian moscovian gzhelian atokan virgilian mixed marine and terrestrial coal bearing strata i e cyclothems in the illinois basin ib are presented in order to determine the dominant pedogenic processes within a cyclic sedimentary depositional framework paleosol morphologies range from weakly developed horizons with evidence of rooting and little to no pedogenic structure to horizons with well developed pedogenic slickensides angular blocky structure and carbonate nodules and tubules the majority of paleosols in strata from the basin interior preserve 1 low chroma gley colors 2 identifiable fossil plant organic matter that increases in abundance upward in the profiles toward the interpreted paleo surface and 3 calcite sphaerosiderite and pyrite cements and nodules in contrast paleosols in strata from the northern margin of the basin display high chroma colors and calcite cements and less fossil organic matter sphaerosiderite and pyrite cements these observations indicate that paleosols from the basin interior underwent a multi phase pedogenic and shallow burial history characterized by an initial better drained oxygenated stage under seasonal precipitation followed by a poorly drained reducing stage while paleosols from the northern margin of the basin experienced overall more oxygenated conditions throughout their pedogenic development x ray diffraction analysis of the 2 m size fraction of paleosol matrix in ib paleosols indicates a mineralogical composition dominated by kaolinite randomly interstratified r0 and ordered r1 illite smectite i s and subordinate amounts of chlorite these combined observational and mineralogical datasets indicate that significant changes in paleohydrology were largely responsible for the development of pennsylvanian soil profiles in the ib

biostratigraphic constraints and depositional environment of thelower cretaceous albian boulder creek formation monkman area northeastern british columbia a full core through the boulder creek formation in the monkman area of northeastern british columbia yielded foraminifera from the overlying hasler formation and underlying hulcross formation ther

lower eocene alluvial paleosols pedogenic development stratigraphic relationships and paleosol landscape associations abstract two kinds of cumulative floodplain paleosols red and grey paleosols formed on overbank deposits of the willwood formation in the sand coulee area of the bighorn basin wyoming although both kinds experienced down profile iron movement due to seasonal saturation of a clay rich a horizon the red paleosols were better drained and their b horizons were rubified various redoximorphic features indicate that the grey paleosols were poorly drained the red paleosols show progressive increases in the degree of profile development away from an associated channel sandstone a paleosol landscape relationship termed pedofacies by bown and kraus 1987 although the grey paleosols show relatively systematic changes in hydromorphy consistent pedofacies changes were not recognized furthermore no lateral relationship between the red and grey paleosols was observed these features suggest that because of the retarding effects of poor drainage on soil weathering poorly drained soils are not amenable to pedofacies modelling and that the landscape associations of well drained and poorly drained soils may be difficult to document without unusually extensive exposures results of this study also show that the pedofacies model is limited by sediment accumulation rates and the kind of fine grained facies on which paleosols developed although readily observable in sand coulee pedofacies are difficult to recognize in the elk creek area where accumulation rates were approximately half as rapid as in sand coulee the attainment of steady state conditions is believed to have obscured pedofacies in the elk creek area finally pedofacies are only developed on true overbank deposits which in the willwood formation and probably many other ancient alluvial sequences make up only a fraction of the fine grained deposits only immature soils formed on the remainder of the fine grained facies because they were deposited very rapidly as a result of channel avulsion

pedosedimentary history and floodplain dynamics of the lower cretaceous upper blairmore group southwestern alberta canada thick alluvial successions in the upper blairmore group in the foothills of southwestern alberta contain few well developed paleosol profiles but abundant evidence of pedogenic modification the pedogenically modified successions are characterized by vertical root traces compound illuvial clay coatings and ferruginous coatings and nodules five representative paleosol successions composed of nine microfacies are analyzed the paleosol successions indicate soil development on more or less continuously aggrading floodplains however locally rates of sedimentation and pedogenesis were highly variable the paleosol successions contain features similar to modern alluvial soils brunisols and luvisols vertical trends within individual paleosol successions preserve the changing paleoenvironmental record at each site the dynamic nature of the floodplain topography is reflected in alternating drainage conditions represented by quasi regular colour banding compound clay coatings and the type and degree of pedogenic development upwards within the paleosol successions overall the paleosols indicate soil development under a warm temperate paleoclimate with seasonal precipitation although representing minor diastems the paleosols formed contemporaneously with sedimentation and are an integral part of the alluvial successions local variations in paleosol development are attributed to variations in sediment supply and water table conditions related to the overall floodplain geomorphology

a new geochemical classification of sedimentary environments because of the relative constancy of ph in most subaqueous sediments and the general lack of measurability of eh these parameters are not practically useful for classifying sedimentary environments in their place a new classification is offered which derived from studies of modern sediments is based on the presence or absence of dissolved oxygen and dissolved sulfide in the sediments at the time of authigenic mineral formation sedimentary environments are first of all divided into oxic and anoxic depending upon the presence or absence of measurable dissolved oxygen anoxic environments in turn are divided into sulfidic and non sulfidic depending upon the presence of measurable dissolved sulfide anoxic nonsulfidic environments are further divided into postoxic or resulting from oxygen removal without sulfate reduction weakly reducing and methanic or resulting from complete sulfate reduction with consequent methane formation strongly reducing the environments are shown to succeed one another during early diagenesis in the order oxic post oxic sulfidic methanic iron and manganese minerals characteristic and stable in each environment are listed and discussed so that they may be used to distinguish the environments when studying the ancient geological record

the habit and origin of siderite spherules in the eocene coal bearing prestfjall formation faroe islands abstract siderite spherules are described and chemically analysed from two localities holi i helli section and rokhagi coal mine within the coal bearing prestfjall formation the formation marks a significant hiatus in the eruption of lava flows of the paleogene faroe islands basalt group and shortly follows the paleocene eocene thermal maximum the spherules are chemically pure although feco 3 80 6 99 2 mol shows a marked substitution for mnco 3 0 1 13 9 mol the low concentrations of mgco 3 0 0 0 4 mol and the lack of associated sulphide minerals e g pyrite confirm the freshwater lake environment affinity of the formation the siderite spherules from the holi i helli section contain significantly higher concentrations of mnco 3 3 may also account for the abundance of siderite spherules formed by the split crystal process in the holi i helli section whereas prefect spherules consisting of individual crystals growing concentrically around a cryptocrystalline centre are dominant from the rokhagi coal mine

high latitude meteoric δ 18 o compositions from the cenomanian bastion ridge formation axel heiberg island canadian arctic archipelago a palaeoclimate proxy from the sverdrup basin

stepwise climate change recorded in eocene oligocene paleosol sequences from central oregon successions of paleosols bounded by erosional surfaces in fluvial sediments of the eocene oligocene strata of central oregon can be interpreted as terrestrial equivalents of the unconformity bound units of sequence stratigraphy in the upper part of the upper eocene clarno formation and in the lower part of the lower eocene lower miocene john day formation truncation surfaces separate otherwise conformable alluvial deposits and allow for stratigraphic subdivision into informal members lower and upper red hill claystones in the clarno formation and lower middle and upper big basin members and lower turtle cove member in the john day formation paleosols in each member show a stepwise change in the degree of weathering of the most strongly developed paleosols kaolinite rich ultisollike paleosols in lower red hill claystones late eocene 42 43 ma smectite rich alfisol like paleosols in the upper red hill claystones late eocene 41 42 ma alfisols and ultisol like paleosols in the lower big

anatomy and evolution of a lower cretaceous alluvial plain sedimentology and palaeosols in the upper blairmore group south western alberta canada the lower cretaceous albian upper blairmore group is part of a thick clastic wedge that formed adjacent to the rising cordillera in south western alberta regional transgressive intervals are superimposed on the overall regressive succession alluvial conglomerates sandstones and mudstones were deposited in east north eastward draining fluvial systems orientated transverse to the basin axis five facies associations have been identified igneous pebble conglomerate thick sandstone interbedded lenticular sandstone and mudstone thick mudstone with thin sandstone interlayers and fossiliferous sandstone and mudstone the facies associations are interpreted as gravelly fluvial channels sandy fluvial channels sand dominated floodplains mud dominated floodplains and marine shoreline deposits respectively five types of palaeosols are recognized in the upper blairmore group based on lithology the presence of pedogenic features clay coatings root traces ferruginous nodules slickensides carbonate nodules and degree of horizonization the regional distribution of the various types of palaeosols enables a refinement of the palaeoenvironmental reconstruction permitting an assessment of the controls on floodplain evolution in source proximal areas palaeosol development was inhibited by high rates of sedimentation in source distal locations poor drainage resulting from high watertables low topography and lower rates of sedimentation also inhibited palaeosol development the best developed palaeosols containing bt horizons occur in intermediate alluvial plain positions tectonic hinge zone where the floodplains were most stable due to a balance between sedimentation erosion and subsidence rates extrapolating from the upper blairmore group suggests that the tectonic hinge zone of continental foreland basins can be established by palaeosol analysis at the hinge zone soil development is controlled primarily by climate and tectonics and their effect on sediment supply whereas closer to the palaeoshoreline relative sea level fluctuations resulting in poor drainage may have a more significant influence

mapping the architecture of glaciofluvial sediments with three dimensional georadar three dimensional 3 d ground penetrating radar georadar mapping offers new opportunities for determining the geometries and facies of surficial sedimentary units to investigate the potential of this high resolution technique and at the same time study the architecture of quaternary glaciofluvial deposits georadar data have been collected on a dense grid established across a sequence of braided river gravels and sands in northeastern switzerland results of this survey are striking 3 d images that provide many more details and much more reliable information on the heterogeneities of the shallow underground than are afforded by conventional georadar profile data continuous subhorizontal and oblique reflections can be traced throughout vertical sections and horizontal slices of the georadar data block to a depth of approx 15 m clearly defined are the dominant flow direction of the ancient braided river system the boundaries between different sedimentary facies and the level of the ground water table trough fill sediments and subhorizontal channel deposits observed on 7 m high quarry walls can be followed confidently in the subsurface the orientation shape and size of the troughs and the strike and dip of the cross bedding are all well resolved

paleopedology and paleohydrology of a volcaniclastic paleosol interval implications for early pleistocene stratigraphy and paleoclimate record olduvai gorge tanzania abstract a cumulative red paleosol interval developed on volcaniclastic parent material under semiarid conditions in olduvai gorge tanzania it contains a complex history of pedogenesis that was affected by 1 episodic pyroclastic and debris fan processes and 2 episodic expansions and contractions of an adjacent alkaline lake and the associated fluctuations in the water table the paleosol interval is 130 320 cm thick represents 25 ka of the 50 kyr duration of lowermost bed ii and is defined by early pleistocene 1 75 ma tuffs if and iia the paleosol interval records a paleocatena related to both landscape and drainage the slope position on a pyroclastic fan relative to an alkaline lake the proximity to freshwater wetlands and the position of water table biogenic paleosol structures include grass and sedge root traces zeolite rhizocretions and soil fauna termite and ant traces abundant pedogenic features sensitive to soil moisture conditions including redoximorphic mottles in the paleosol matrix fe oxide glaebules grain and pore coatings illuviated clay grain and pore coatings and vadose siliciclastic and zeolite crystal silt record episodic water table fluctuations the geochemistry of whole rock samples distinguishes two parent materials early low ti zr weathered volcaniclastic sediment and late high ti zr tuffaceous sediment which represent two distinct pedogenic phases the lower paleosol developed at both sites whereas the upper paleosol developed only at the upslope site mass balance calculations indicate greater weathering higher eh and ph and greater zeolite precipitation at the upslope site than at the downslope site these relationships are compatible with the upslope site having had a lower overall water table and better drained conditions than the downslope site which had a higher water table and poorly drained conditions the lower paleosol provides evidence of a fluctuating water table consistent with a wetter climate followed by a prolonged arid period the upper paleosol began to form after a return to wetter conditions and ended under arid conditions the position of the olduvai subchron c2n 1 942 1 785 ma in bed i directly beneath the paleosol interval is used to make a tentative correlation at 1 75 ma with global climate dust records wet dry cycles

multiple paleosols of the late albian boulder creek formation british columbia canada fifteen lithified paleosols closely spaced in vertical sequence occur in the top 90 m of the late albian boulder creek formation in the foothills of northeastern british columbia canada the paleosols have well developed profiles 0 5 to 1 5 m thick including a b and c horizons the paleosols are characterized by their grey colour cutans vertical roots peds spherulitic siderite and absence of sedimentary structures the paleosols formed during a period when one or more basin wide unconformities occurred as a result of either eustatic sea level fluctuations or local tectonic events these unconformities represent the terrestrial record of a lowered base level which caused valley incision and decreased rates of sedimentation on the incised flood plain the climate was humid to subhumid overall the environment in which these soils developed was of low relief and subject to little erosion the water table was high for part of the year but there is also evidence of periodic drying and oxidation of organic debris cumulatively the paleosols in this interval may represent 150000 yr of non deposition

late jurassic paleogeography and paleoclimate in the northern iberian basin of spain constraints from diagenetic records in reefal and continental carbonates abstract sedimentation in the northern part of the iberian basin during the early kimmeridgian was characterized by the development of coral reef complexes of the torrecilla en cameros formation which were situated along a seaway that connected the boreal and tethys domains along the northern portion of that seaway close to the boreal sea early diagenesis of the torrecilla fringing reef complex was controlled by rising sea level and by local tectonism leading to alternations of submergence and reefal exposure while exposed reef corals were neomorphosed and dissolved when the corals were submerged secondary porosity was filled by calcite cements precipitated from marine derived waters during the latest stages of reef development rate of sea level rise could no longer keep pace with tectonic uplift and while younger accretionary units continued to be deposited older units were exposed subaerially leading to the precipitation of meteoric calcite cement and to the development of a paleosol this stage of diagenesis also affected the reef complex during late kimmeridgian times as the boreal and tethys coastlines progressively retreated to the north and southeast respectively progressive retreat of the boreal sea and subsequent late jurassic to early cretaceous rifting that formed the cameros basin resulted in the deposition of tithonian continental carbonates directly on these reefal units oxygen isotope compositions of these continental carbonates are 3 more negative than kimmeridgian meteoric cement suggesting an evolution in the isotopic composition of meteoric water in response to an increasing continental effect on meteoric precipitation in contrast early kimmeridgian reef complexes of the torrecilla en cameros formation in the southern sectors of the seaway closer to the tethys sea were exposed during the late kimmeridgian as the tethys coastline retreated leading to dissolution of corals and subsequent precipitation of meteoric calcite cement oxygen isotope compositions of these meteoric cements are 2 more negative than time equivalent meteoric calcites precipitated in the northern torrecilla reef complex given the regional paleogeography this difference suggests that sources of meteoric water must have been different for the northern and southern sectors and probably reflects southward transport of air masses and water vapor from the boreal sea to the northern torrecilla sector and northwest transport of water vapor from the tethys sea to the southern sectors tithonian berriasian continental carbonates which unconformably overlie reef complexes in the southern and northern sectors exhibit an opposite trend with the 18o of continental carbonates in southern sectors being 1 6 more positive than time equivalent carbonates that overlie the torrecilla reef complex to the north this shift in the trend of the isotopes between northern and southern sectors is coeval with paleogeographic changes that occurred in response to late jurassic early cretaceous rifting of the iberian plate and the progressive retreat of boreal and tethys coastlines during this time continental carbonates in both the southern and northern sectors of the seaway precipitated from meteoric waters that were sourced from the tethys sea to the southeast more negative 18o values in the northern torrecilla sector reflect enhanced continental fractionation effects as the influence of the boreal sea derived meteoric waters diminished

three dimensional ground penetrating radar imaging of sedimentary structures fractures and archaeological features at submeter resolution contemporary geoscientific shallow subsurface assessment chiefly relies on outcrops drilling excavations and sometimes geophysics often the information gathered is insufficient to accurately characterize the archaeological and or geologic record and ongoing shallow subsurface processes that affect a variety of economic and environmental aspects of our society the extra effort of acquiring very dense ground penetrating radar gpr survey grids and three dimensional 3d data processing transforms uncorrelatable and uninterpretable gpr signals into clear images of complex shallow subsurface anatomy with an unprecedented resolution here we present two examples of noninvasive 3d shallow subsurface imaging example 1 images decimeter to meter scale sedimentary structures in a pleistocene oolite shoal barrier bar setting example 2 images the fracture network in a triassic limestone quarry denser than quarter wavelength grid acquisition in combination with 3d migration processing focuses scattered energy and removes out of plane reflections in addition to conventional vertical cross sections horizontal depth slices and data volume animations reveal previously unseen diagnostic patterns of past human activities laterally changing depositional processes and fracture networks including near vertical joints with millimeter apertures

precipitation rates and atmospheric heat transport during the cenomanian greenhouse warming in north america estimates from a stable isotope mass balance model stable isotope mass balance modeling results of meteoric 18o values from the cenomanian stage of the cretaceous western interior basin kwib suggest that precipitation and evaporation fluxes were greater than that of the present and significantly different from simulations of albian kwib paleohydrology sphaerosiderite meteoric 18o values have been compiled from the lower tuscaloosa formation of southwestern mississippi 25 n paleolatitude the dakota formation rose creek pit fairbury nebraska 35 n and the dunvegan formation of eastern british columbia 55 n paleolatitude these paleosol siderite 18o values define a paleolatitudinal gradient ranging from 4 2 vpdb at 25 n to 12 5 vpdb at 55 n this trend is significantly steeper and more depleted than a modern theoretical siderite gradient 25 n 1 7 65 n 5 6 vpdb and a holocene meteoric calcite trend 27 n 3 6 67 n 7 4 vpdb the cenomanian gradient is also comparatively steeper than the albian trend determined for the kwib in the mid to high latitudes the steep latitudinal trend in meteoric 18o values may be the result of increased precipitation and evaporation fluxes amount effects under a more vigorous greenhouse world hydrologic cycle a stable isotope mass balance model has been used to generate estimates of precipitation and evaporation fluxes and precipitation rates estimates of cenomanian precipitation rates based upon the mass balance modeling of the kwib range from 1400 mm yr at 25 n paleolatitude to 3600 mm yr at 45 n paleolatitude the precipitation evaporation p e flux values were used to delineate zones of moisture surplus and moisture deficit comparisons between cenomanian p e and modern theoretical siderite and holocene calcite latitudinal trends shows an amplification of low latitude moisture deficits between 5 25 n paleolatitude and moisture surpluses between 40 60 n paleolatitude the low latitude moisture deficits correlate with a mean annual average heat loss of 48 w m2 at 10 n paleolatitude present 8 w m2 at 15 n the increased precipitation flux and moisture surplus in the mid latitudes corresponds to a mean average annual heat gain of 180 w m2 at 50 n paleolatitude present 17 w m2 at 50 n the cenomanian low latitude moisture deficit is similar to that of the albian however the mid latitude 40 60 n precipitation flux values and precipitation rates are significantly higher albian 2200 mm yr at 45 n cenomanian 3600 mm yr at 45 n furthermore the heat transferred to the atmosphere via latent heat of condensation was approximately 10 6 that of the present at 50 n the intensified hydrologic cycle of the mid cretaceous greenhouse warming may have played a significant role in the poleward transfer of heat and more equable global conditions paleoclimatological reconstructions from multiple time periods during the mid cretaceous will aid in a better understanding of the dynamics of the hydrologic cycle and latent heat flux during greenhouse world conditions

paleosols in the cretaceous goshoura and mifune groups sw japan and their paleoclimate implications abstract cretaceous sedimentary basins in kyushu island japan are developed as half grabens which accommodated very thick clastic wedges of non marine to shallow marine facies the albian to cenomanian goshoura group in western kyushu ca 1000 m thick consists of interbedded channel sandstone conglomerate and mudstone the cenomanian to turonian mifune group in central kyushu ca 2300 m thick comprises red and drab sandstone and intercalated siliceous ash fall tuff different types of paleosols occur in the goshoura and mifune groups paleosols in the goshoura group contain diagnostic vertic features such as subangular blocky peds irregularly directed slickensides and downward tapering fissures few obvious calcic horizons are developed except for the calcretes of rhizogenic origin paleosols in the upper formation of the mifune group are composed of cyclic acidic tuff vertic paleosol intervals with abundant pedogenic calcretes paleosols of the goshoura group belong to the order of vertic inceptisols and those of the mifune group can be classified as calcic vertisols in spite of diagenetic alteration of the paleosols paleo vertic soils of the goshoura and mifune groups show the exceptional preservation of a number of pedological features among various soil forming factors diversity in each paleosol is mainly attributed to differences in paleoclimatic conditions during the middle cretaceous our results show that the paleoclimatic conditions in the subtropical warm temperate region had changed from subhumid to semi arid with time

the mid cretaceous water bearer isotope mass balance quantification of the albian hydrologic cycle a latitudinal gradient in meteoric n 18 o compositions compiled from paleosol sphaerosiderites throughout the cretaceous western interior basin kwib 34 75 n paleolatitude exhibits a steeper more depleted trend than modern predicted values 3 0x 34 n latitude to 9 7x 75 n lighter furthermore the sphaerosiderite meteoric n 18 o latitudinal gradient is significantly steeper and more depleted 5 8x 34 n to 13 8x 75 n lighter than a predicted gradient for the warm mid cretaceous using modern empirical temperature n 18 o precipitation relationships we have suggested that the steeper and more depleted relative to the modern theoretical gradient meteoric sphaerosiderite n 18 o latitudinal gradient resulted from increased air mass rainout effects in coastal areas of the kwib during the mid cretaceous the sphaerosiderite isotopic data have been used to constrain a mass balance model of the hydrologic cycle in the northern hemisphere and to quantify precipitation rates of the equable greenhouse albian stage in the kwib the mass balance model tracks the evolving isotopic composition of an air mass and its precipitation and is driven by latitudinal temperature gradients our simulations indicate that significant increases in albian precipitation 34 52 and evaporation fluxes 76 96 are required to reproduce the difference between modern and albian meteoric siderite n 18 o latitudinal gradients calculations of precipitation rates from model outputs suggest mid high latitude precipitation rates greatly exceeded modern rates 156 220 greater in mid latitudes 2600 3300 mm yr 99 greater at high latitudes 550 mm yr the calculated precipitation rates are significantly different from the precipitation rates predicted by some recent general circulation models gcms for the warm cretaceous particularly in the mid to high latitudes our mass balance model by no means replaces gcms however it is a simple and effective means of obtaining quantitative data regarding the mid cretaceous hydrologic cycle in the kwib our goal is to encourage the incorporation of isotopic tracers into gcm simulations of the midcretaceous and to show how our empirical data and mass balance model estimates help constrain the boundary conditions

eocene hydromorphic paleosols significance for interpreting ancient floodplain processes abstract pervasive mottling iron oxide nodules and slickensides indicate that alluvial paleosols of the lower eocene willwood formation in the elk creek area of the bighorn basin wyoming were hydromorphic two basic groups of hydromorphic paleosols are present cumulative which show evidence for concurrent deposition and pedogenesis and simple noncumulative which show evidence for a single episode of deposition and pedogenesis lithologic packages consisting of vertically stacked simple paleosols and crevasse splay sandstones alternate with cumulative paleosols the simple paleosols are weakly developed indicating rapid deposition with relatively little time for pedogenesis cumulative paleosols show greater pedogenic development indicating significantly longer periods of pedogenic m dification and slower more episodic sediment accumulation differences between the simple and cumulative paleosols reflect differences in the deposition of their parent materials the packages of simple paleosols are similar to avulsion belt deposits described from the saskatchewan river and suggest that avulsion was significant in floodplain construction the upper parts of cumulative paleosols were formed on true overbank deposits which accumulated gradually after avulsion and establishment of a new channel the lower parts of many cumulative paleosols resulted from a prior episode of avulsion deposition and simple soil formation because hydromorphy is associated with texture these different depositional processes influenced lateral variations in hydromorphy of the cumulative paleosols paleosols in the elk creek area provide a simple means of identifying avulsions sediment accumulation rates suggest that avulsions occurred with a regular period of about 20 000 years and may have been induced by climatic cycles

pedogenic and diagenetic influences on void coating formation in lower cretaceous paleosols of the mill creek formation southwestern alberta canada abstract pedogenic and diagenetic influences on void coating formation were studied in two paleosols from the lower cretaceous albian mill creek formation in southwestern alberta canada using detailed micromorphological mineralogical and geochemical methods the paleosols consist of alternating decimetre scale beds of red grey green and variegated mudstone intermediate horizons red and grey green variegated mudstones contain associations of pale yellow clay coatings dark red clay coatings fe depletion hypo coatings and fe oxide quasi coatings sem edx ray analyses indicate that the dark reddish coatings are dominated by si al and fe with subordinate amounts of k na ca mg and ti pale yellow clay coatings have a higher si content and lower al k na ca and fe contents relative to reddish coatings within the paleosol profiles the distribution of clay minerals indicates 1 an increase in discrete clay minerals downward 2 a decrease in mixed layer illite smectite downward and 3 an increase in chlorite upward x ray diffraction indicates that the pale yellow and dark red clay void coatings are polymineralic pale yellow clay coatings have a higher proportion of mixed layer illite smectite and kaolinite less chlorite and are less crystalline than dark reddish coatings despite a diagenetic overprint including development of diffusion gleyans degradation of organic matter burial reddening and probably some smectite illitization both compositional and morphological gradients exist in the paleosol profiles and void coatings these gradients are most likely related to depositional variations and to pedogenic development in the original soils under variable eh ph conditions in the presence of organic matter therefore although the void coatings are altered diagenetic features their morphology mineralogy and perhaps even some of their microchemistry is attributable to the presence of pedogenic precursors initially formed in soils similar to modern temperate alfisols and glossic soils

quantification of a greenhouse hydrologic cycle from equatorial to polar latitudes the mid cretaceous water bearer revisited article this study aims to investigate the global hydrologic cycle during the mid cretaceous greenhouse by utilizing the oxygen isotopic composition of pedogenic carbonates calcite and siderite as proxies for the oxygen isotopic composition of precipitation the data set builds on the aptian albian sphaerosiderite 18 o data set presented by ufnar et al 2002 by incorporating additional low latitude data including pedogenic and early meteoric diagenetic calcite 18 o ufnar et al 2002 used the proxy data derived from the north american cretaceous western interior basin kwib in a mass balance model to estimate precipitation evaporation fluxes we have revised this mass balance model to handle sphaerosiderite and calcite proxies and to account for longitudinal travel by tropical air masses we use empirical and general circulation model gcm temperature gradients for the mid cretaceous and the empirically derived 18 o composition of groundwater as constraints in our mass balance model precipitation flux evaporation flux relative humidity seawater composition and continental feedback are adjusted to generate model calculated groundwater 18 o

ground penetrating radar reflection profiling of groundwater and bedrock in an area of discontinuous permafrost we have used ground penetrating radar to profile the depth of permafrost to groundwater beneath permafrost and to bedrock within permafrost in alluvial sediments of interior alaska we used well log data to aid the interpretations and to calculate dielectric permittivities for frozen and unfrozen materials interfaces between unfrozen and frozen sediments above permafrost were best resolved with wavelet bandwidths centered at and above 100 mhz the resolution also required consideration of antenna configuration season and surface conditions depths to subpermafrost groundwater were profiled where it was in continuous contact with the bottom of the permafrost except near transitions to unfrozen zones where the contact appeared to dip steeply the complexity of the responses to intrapermafrost bedrock detected at a maximum depth of 47 m appears to distinguish these events from those of subpermafrost saturated sediments the relative dielectric permittivity ranged between 4 4 and 8 3 for the permafro

estimating 3d variation in active layer thickness beneath arctic streams using ground penetrating radar we acquired three dimensional 3d ground penetrating radar gpr data across three stream sites on the north slope ak in august 2005 to investigate the dependence of thaw depth on channel morphology data were migrated with mean velocities derived from multi offset gpr profiles collected across a stream section within each of the 3d survey areas gpr data interpretations from the alluvial lined stream site illustrate greater thaw depths beneath riffle and gravel bar features relative to neighboring pool features the peat lined stream sites indicate the opposite greater thaw depths beneath pools and shallower thaw beneath the connecting runs results provide detailed 3d geometry of active layer thaw depths that can support hydrological studies seeking to quantify transport and biogeochemical processes that occur within the hyporheic zone

sinkhole structure imaging in covered karst terrain 1 ground penetrating radar gpr and resistivity techniques have been widely used to map the locations of sinkholes in covered karst terrain to determine whether a sinkhole is a likely preferential conduit for groundwater flow however requires higher resolution imaging than that used in conventional sinkhole mapping surveys field observations combined with simulated surveys for a 15 m diameter 3 m deep sinkhole in west central florida are used to assess the resolution of gpr and resistivity surveys targeting the semiconfining unit that floors the sinkhole depression 2d resistivity surveys clearly show the central depression as well as resistivity contrasts between the cover sediments within and outside of the sinkhole but are inadequate for resolving breaches in the semiconfining unit or underlying conduits a 3d gpr survey resolves vertical structure on the order of tens of centimeters within the semiconfining unit as well as indicators of conduits that extend several meters beneath the central depression 3d gpr thus holds promise for imaging hydrologically significant features of sinkholes

diagenesis of fossiliferous concretions from the upper cretaceous fox hills formation north dakota abstract three fossiliferous concretions of the fox hills formation upper cretaceous of north dakota display similar diagenetic histories petrographic and geochemical data from each concretion have yielded the following diagenetic sequence 1 bioturbation by marine benthos 2 partial phosphatization of glauconite fecal pellets and shell material 3 sulfate reduction and pyrite formation 4 siderite precipitation 5 radial fibrous calcite precipitation and 6 equant calcite precipitation although the occurrence of open marine faunas and glauconite indicates that concretion sediments were deposited under marine conditions geochemical data suggest that marine pore fluids were replaced by brackish and meteoric water as the fox hills formation is part of a regressive marginal marine equence it is likely that the transition from marine to freshwater is recorded in concretion paragenesis early diagenetic minerals indicate oxidation of organic matter at shallow burial depths under normal marine conditions locally reducing conditions produced initially by degradation of molluscan soft parts and later by degradation of organic material in crustacean and annelid fecal pellets occurred at shallow burial depths alteration of iron silicates glauconite produced pore fluids enriched in fe2 due to the abundance of reactive organic matter subsequent reduction of marine sulfate yielded a small amount of disseminated pyrite following the removal of h2s elevated fe2 ph and bicarbonate concentrations soon exceeded siderite saturation and siderite was precipitated elevated ca and mg compositions and marine 18o values of siderite cements indicate that pore fluids were essentially reduced marine fluids depleted 13c values suggest that siderite precipitated in an environment dominated by the oxidation of organic matter isotopic compositions from the earliest and latest carbonate phases constrain intermediate phases and allow comparison of environments of precipitation carbon and oxygen isotopic data from skeletal aragonite provide an estimate of the isotopic composition of marine carbonate the latest phase of equant calcite cement is characterized by invariant 18o coupled with highly variable and light 13c this characteristic isotopic signature and occurrence in overlying fluvial sediments suggests a meteoricphreatic origin for equant spars isotopic values of radial fibrous calcite lie between those of marine aragonite siderite and freshwater equant calcite ph ses and represent a complex mixing of marine and meteoric pore fluids the paragenetic sequence of carbonate cements records a gradual decrease in ambient fluid mg fe and mn content during shallow burial such decreases are consistent with the influx of oxidizing meteoric fluids

a warm equable cretaceous the nature of the problem abstract the nature of the problem of warm equable paleoclimates is defined by investigating the mid cretaceous period the problem consists of three components 1 defining precisely the climatic state during any specified interval of geologic time 2 specifying the external climatic forcing factors which may have been important and 3 understanding the climatic response to any specific modifying influence these components are characterized by limitations of critical importance in understanding paleoclimates the nature of the problem of a warm cretaceous is defined both qualitatively and quantitatively within these limits

implications of magnetotelluric modeling for the deep crustal environment in the rio grande rift abstract block forward modeling and smooth backus gilbert linearized inversion have independently been used to two dimensionally model two east west magnetotelluric profiles in the central rio grande rift a crustal conductive zone of at least 1500 s has been detected at about 10 km depth along the northern line however along a line 40 km to the south where shallow active magma is inferred and microseismicity is highest no high conductivity zone is found the conductive zone beneath the northern line is hypothesized to occur where water is trapped beneath an undisturbed ductile cap under the southern line magma injection through the cap may release the water thereby resulting in a relatively more resistive crust with no conductive midcrustal layer the resulting paradox is that where there is active magma injection into the upper crust of the rio grande rift the crust is more resistive rather than more conductive

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

paleopedology and stable isotope chemistry of late silurian vertic paleosols bloomsburg formation central pennsylvania abstract paleosols with vertic vertisol like features occur in repetitively stacked fining upward sequences bounded by marine erosional surfaces in the bloomsburg formation ludlovian to pridolian of central pennsylvania paleosol development was strongly influenced by repeated changes in relative sea level which resulted in subaerial exposure and pedogenesis of marginal marine sediment accumulating along a low energy mud dominated coastline in a delta plain environment bloomsburg paleosols are characterized by very weak horizonation abundant pedogenic slickensides and a micromorphology dominated by sepic fabrics and peds bounded by stress cutans pedogenic carbonate is sparse occurring principally as micrite nodules stable carbon isotope compositions of stratigraphically low pedogen c carbonate mean 13c 1 92 pdb are attributed to pedogenesis proximal to a marine coastline in stratigraphically high paleosols showing evidence of rhizolith development isotopic compositions of pedogenic carbonate suggest a significant contribution of carbon from c3 flora atmospheric p co2 levels estimated for these calcretes 4500 5500 ppmv are significantly greater than present day values low 18o values for pedogenic carbonate mean 18o 12 12 pdb record isotopic exchange between paleosol carbonate and 18o enriched fluids associated with the conversion of original soil smectites to illite and chlorite during burial diagenesis paleosols bounded by marine erosional surfaces show variable degrees of marine hydromorphism attributable to rising water table during transgression evidence for hydromorphism includes extensive reduction of iron as well as relative increases in cao mno mgo p2o5 na2o and sr at the tops of paleosols due to introduction of marine fluids and sediment into open soil fractures and burrows the abundance of vertic features in all bloomsburg paleosols by analogy with holocene vertisols indicates the recurrence of a seasonally wet dry dry 4 8 months year paleoclimate n the central appalachian region at a paleolatitude of about 20 south

meteoric sphaerosiderite lines and their use for paleohydrology and paleoclimatology sphaerosiderite a morphologically distinct millimeter scale spherulitic siderite feco 3 forms predominantly in wetland soils and sediments and is common in the geologic record ancient sphaerosiderites are found in paleosol horizons within coal bearing stratigraphic intervals and like their modern counterparts are interpreted as having formed in water saturated environments here we report on sphaerosiderites from four different stratigraphic units each of which has highly variable 13 c and relatively stable 18 o compositions the unique isotopic trends are analogous to well documented meteoric calcite lines which we define here as meteoric sphaerosiderite lines meteoric sphaerosiderite lines provide a new means of constraining ground water 18 o and thus allow evaluation of paleohydrology and paleoclimate in humid

foraminiferal inventory and lithologic description of the lower cretaceous albian hulcross shale monkman area northeastern british columbia correlation of an arenaceous microfauna of 41 species 44 subspecies from the hulcross formation of the monkman pass area with that found in the hulcross shale on the peace river has a further corroboration in matching spectra of volcanic ash beds at both localities the monkman pass equivalents of both the basalmost portion and the upper part of the hulcross beds on the peace river are in sandy to continental facies diatoms are plentiful in the monkman pass section in the shaly facies the foraminiferal genera include bathysiphon thuramminoides psammosphaera hippocrepina saccammina reophax glomospira ammodiscus psamminopelta haplophragmoides ammobaculites trochammina textulariopsis pseudobolivina verneuilinoides uvigerinammina gaudryina eggerella and dorothia only thuramminoides haplophragmoides and trochammina occur in abundance indicating water of depth around 100 m at time of deposition and of salinity close to that of normal seawater the low degree of bioturbation and the pres

well preserved late precambrian paleosols from northwest scotland abstract two paleosol profiles were developed side by side on gneiss sheigra clay paleosol and amphibolite staca clay paleosol along the same unconformable contact of lewisian metamorphic rocks 2 7 1 7 ga overlain by torridonian sandstones 0 8 ga in northwestern scotland although altered during burial by compaction and illitization these profiles are well preserved compared with most other precambrian paleosols that are metamorphosed to at least greenschist facies in addition deformation of pegmatite veins in a manner similar to soil creep can be taken as an indication that upper horizons of these paleosols have been preserved soil development in both profiles was characterized by the oxidation of iron in biotite and magnetite and by hydrolysis of plagioclase orthoclase and hornblende clay skins soil like microfabrics and pedogenic smectite have been preserved in the profiles alteration of silicate grains other than quartz microcline and biotite has been intense but chemical analyses failed to show dramatic removal of alkalis and alkaline earths from the profiles microscopic concretions similar to pedogenic carbonate were found in subsurface horizons of the staca clay rare earth elements are more abundant within the paleosols than in their parent materials these paleosols developed on a well drained landscape that was buried by torridonian alluvial fans atmospheric oxidation was greater than revealed by studies of archean paleosols but probably still short of modern levels paleoclimate was subhumid and probably seasonal organic carbon and its light isotopic composition in the paleosol is evidence for photosynthetic microbial crusts paleosols of such great antiquity do not fit comfortably within modern soil taxonomies and are for the moment assigned to the informal category of green clays

formation of siderite mg calcite iron sulphide concretions in intertidal marsh and sandflat sediments north norfolk england concretions cemented mainly by siderite mg calcite and iron monosulphide are common in late holocene marsh and sandflat sediments on parts of the north norfolk coast field experiments have shown that the concretions are actively forming in reduced sediments in which sulphate reducing bacteria are active 13c values ranging from 3 to 11 8 mean 5 9 0 suggest that the carbonate in the concretions is derived partly from marine sources and partly from microbial degradation of organic matter 18o values ranged from 6 4 to 0 8 mean 1 0 suggesting that carbonate precipitated in porewaters ranging from pure sea water to sea water diluted with meteoric water chemical analysis of porewaters showed no evidence of significant sulphate depletion at the depth of concretion formation some concretions have formed around fragments of wood or metal but others contain no apparent nucleus in field experiments siderite fes and mg calcite were precipitated around several different nuclei within a period of six months we suggest that siderite may form wherever the rate of iron reduction exceeds the rate of sulphate reduction such that insufficient dissolved sulphide is available to precipitate all the available dissolved ferrous iron

diagenetic overprinting of the sphaerosiderite palaeoclimate proxy are records of pedogenic groundwater delta18o values preserved meteoric sphaerosiderite lines msls defined by invariant d 18 o and variable d 13 c values are obtained from ancient wetland palaeosol sphaerosiderites millimetre scale feco3 nodules and are a stable isotope proxy record of terrestrial meteoric isotopic compositions the palaeoclimatic utility of sphaerosiderite has been well tested however diagenetically altered horizons that do not yield simple msls have been encountered well preserved sphaerosiderites typically exhibit smooth exteriors spherulitic crystalline microstructures and relatively pure 95 mol feco3 compositions diagenetically altered sphaerosiderites typically exhibit corroded margins replacement textures and increased crystal lattice substitution of ca 2 m g 2 and mn 2 for fe 2 examples of diagenetically altered cretaceous sphaerosideritebearing palaeosols from the dakota formation kansas the swan river formation saskatchewan and the success s2 formation saskatchewan were examined in this study to determine the extent to which original early diagenetic d 18 o and d 13 c values are preserved all three units contain poikilotopic calcite cements with significantly different d 18 o and d 13 c values from the co occurring sphaerosiderites the complete isolation of all carbonate phases is necessary to ensure that inadvertent physical mixing does not affect the isotopic analyses the dakota and swan river samples ultimately yield distinct msls for the sphaerosiderites and mcls meteoric calcite lines for the calcite cements the success s2 sample yields a covariant d 18 o vs d 13 c trend resulting from precipitation in pore fluids that were mixtures between meteoric and modified marine phreatic waters the calcite cements in the success s2 formation yield meteoric d 18 o and d 13 c values a stable isotope mass balance model was used to produce hyperbolic fluid mixing trends between meteoric and modified marine end member compositions modelled hyperbolic fluid mixing curves for the success s2 formation suggest precipitation from fluids that were 25 sea water

basin scale dolomite cementation of shoreface sandstones in response to sea level fall this study documents a link between sea level fall and basin scale dolomite cementation of shoreface sandstones in the upper cretaceous desert member book cliffs utah by integrating sedimentology sequence stratigraphy and sedimentary geochemistry within the desert member shoreface sandstones a number of high frequency sequence boundaries formed as a result of relative sea level falls that led to localized incised valley formation subaerial exposure and meteoric leaching of upper shoreface sandstones shoreface sandstones up to 10 km downdip from these subaerial exposure surfaces contain ferroan dolomite concretion bodies as much as 8 m thick basinward of this smaller as much as 1 m in size less abundant dolomite concretions can be traced at the same horizons some 1 8 o data suggest that cement precipitated from porewater with a significant meteoric component although reequilibration and recyrstallization cannot be eliminated some 1 3 c data suggest carbonate derivation from detrital dolomite leached from beneath organic rich coastal plain strata deposited during high frequency sequence boundary development we propose that during high frequency sequence boundary formation meteoric fluids migrated basinward into shoreface sandstones as a result of the relative fall in sea level the precipitation of dolomite cement in the shoreface sandstones was promoted by the updip dissolution and remobilization of detrital dolomite by the meteroic fluids mixing with marine pore fluids and the presence of detrital dolomite in the shoreface sandstones which acted as nucleation sites for dolomite precipitation this study illustrates the impact of stratigraphic development upon basin scale early diagenetic cementation of siliciclastic succcesions

reconstructing a mid cretaceous landscape from paleosols in western canada abstract the albian stage of the mid cretaceous was a time of equable climate conditions with high sea levels and broad shallow epeiric seas that may have had a moderating affect on continental climates a late albian landscape surface that developed during a regression and subsequent sea level rise in the western canada foreland basin is reconstructed on the basis of correlation of paleosols penetrated by cores through the paddy member of the peace river formation reconstruction of this landscape refines chronostratigraphic relationships and will benefit future paleoclimatological studies utilizing continental sphaerosiderite proxy records the paleosols developed in estuarine sandstones and mudstones and they exhibit evidence of a polygenetic history upon initial exposure and pedogenesis the paddy member developed deeply weathered well drained cumulative soil profiles later stages of pedogenesis were characterized by hydromorphic soil conditions the stages of soil development interpreted for the paddy member correlate with inferred stages of pedogenic development in time equivalent formations located both basinward and downslope upper viking formation and landward and upslope boulder creek formation on the basis of the genetic similarity among paleosols in these three correlative formations the paleosols are interpreted as having formed along a single continuous landscape surface results of this study indicate that the catena concept of pedogenesis along sloping landscapes is applicable to ancient successions sphaerosiderites in the paddy member paleosols are used to provide proxy values for meteoric 18o values at 52 n paleolatitude in the cretaceous western interior basin the meteoric 18o values are used to refine existing interpretations about the mid cretaceous paleolatitudinal gradient in meteoric 18o values and the mid cretaceous hydrologic cycle

3 d ground penetrating radar applied to fracture imaging in gneiss three dimensional ground penetrating radar georadar techniques suitable for geological engineering applications have been developed and tested initial experiments were conducted on the floor of a quarry in southern switzerland from which ornamental gneissic rock is extracted during a brief two day period constant offset georadar data were recorded over a 650m2 area with a grid cell size of 0 1 m 0 2 m georadar velocities were estimated from the results of expanding spread surveys all georadar data and associated geometry files were recorded automatically in seismic industry formats the experimental georadar data set was processed image enhanced and interpreted using 3 d seismic reflection software operating on a workstation arbitrary vertical sections time slices 3 d images and animated movies in which the observer travels through the entire data volume were constructed from the resultant migrated georadar data semi automatic tracking routines allowed continuous subhorizontal reflectio

palaeosols and sequence stratigraphy of the lower permian abo member south central new mexico usa the relationship between palaeosols and sequence stratigraphy is tested in the lower permian abo member south central new mexico by comparing interfluve and fluvial terrace palaeosols with palaeosols that developed within lowstand fluvial deposits interfluve and fluvial terrace palaeosols consist of primary pedogenic features including vertical root traces vertic structures stage ii and iii pedogenic calcite and translocated clay argillans which are cross cut or replaced by low aluminium goethite gley colour mottling sparry calcite veins and ankerite the polygenetic character of the palaeosols is consistent with initial development for several thousand to tens of thousands of years on well drained interfluves or fluvial terraces followed by waterlogging due to invasion by a rising water table that locally may have been brackish in contrast lowstand fluvial sediment that filled incised valleys contains only rooted and vertic palaeosols whose immaturity resulted from high aggradation rates palaeosols similar to those in the abo member have been recognized in other ancient strata and when combined with highresolution correlation provide evidence for interpretation of sequencestratigraphic surfaces and systems tracts

use of ground penetrating radar to map subsurface archaeological features in an urban area the ground penetrating radar gpr technique was used to investigate the subsurface in an urban area located in mesagne italy to obtain a map of the archaeological features in the ground the gpr survey was undertaken at selected locations placed near about 50 m to a necropolis dating from the messapian to the roman imperial age using a gssi sir system 2 incorporating 200 and 500 mhz centre frequency antennae the selected areas a and b were surveyed along parallel 1 m spaced profiles using a 200 mhz antenna in area a and along parallel 0 5 m spaced profiles using a 500 mhz antenna in area b for the selected areas the processed data were visualised in 3d space not only by means of the standard time slice technique but also by means of a recently proposed approach namely by iso amplitude surfaces of the complex trace amplitude the immediacy in revealing the spatial positioning of highly reflecting bodies such as the anomaly interpreted as an old hypogeum room in area a makes 3d visualisation techniques very attractive in archaeological applications of gpr their sensitivity to the signal noise ratio is on the other hand highlighted by the quite poor performance in area b where the only reliable result provided by all the techniques was the ancient living surface reflection whereas none of them could effectively enhance the visibility of weak hyperbola reflections noted on 2d sections and probably related to the walls located on the ancient living surface the performance of the various techniques in these two different situations allowed insights into their main advantages and drawbacks to be gained

use of micromorphology for palaeoenvironmental interpretation of complex alluvial palaeosols an example from the mill creek formation albian southwestern alberta canada abstract field observations are often not sufficient for process based interpretations of palaeosols particularly where they form parts of thick aggradational pedocomplexes within alluvial successions under such conditions micromorphology provides genetic temporal and spatial information on soil forming processes that is critical to an understanding of past environmental conditions thick alluvial successions of the albian mill creek formation contain abundant evidence of pedogenesis but few well developed palaeosol profiles and therefore provide an ideal case study in which to demonstrate the usefulness of micromorphological data for palaeoenvironmental interpretation the micromorphological features of greatest interpretive value are types of clay coatings and ferruginous segregations structure and fabric papules evidence of bioactivity and ferruginous concretions provide information on geomorphic surface stability and assist in reconstructing temporal changes in drainage conditions while individual features can provide some palaeoenvironmental information the relationships of features to one another and assemblages of features provides additional information when analysed hierarchically to establish a sequence of sedimentologic and pedogenic events a common recurring sequence of palaeoenvironmental events subject to local variations can be recognized throughout the mill creek formation the presence of illuvial clay requires that water percolated through the soil and that the soil periodically dried out so that the translocated clay was retained dark reddish clay coatings indicate clay illuviation under freely drained conditions while pale yellow and silty clay coatings suggest that phases of free drainage alternated with phases of poorly drained or saturated soil conditions the presence of iron depletion coatings iron nodules and quasiferrans indicates that these units were at least periodically saturated and the occurrence of multiple overlapping phases within single thin sections demonstrates that redox conditions fluctuated strongly suggesting development in the vadose zone recent soils containing similar assemblages of features develop under warm temperate seasonal climates alternating phases of well drained and saturated conditions on the mill creek floodplains are attributed to changing sediment supply and local palaeogeomorphology rather than to any major regional climate change this type of process based micromorphological analysis should have broad application in other complex pedogenically modified alluvial successions and similar studies would lead to a more detailed understanding of ancient palaeoenvironments

origin and diagenetic evolution of ca mg fe carbonates in some coalfields of japan carbonate concretions lenses and bands in the pleistocene palaeogene and upper triassic coalfields of japan consist of various carbonate minerals with varied chemical compositions authigenic carbonates in freshwater sediments are siderite calcite ankerite dolomite ferroan magnesite in brackish water to marine sediments in the coal measures calcite dolomite ankerite siderite ferroan magnesite and in the overlying marine deposits calcite dolomite siderite most carbonates were formed progressively during burial within a range of depths between the sediment water interface and approximately 3 km the mineral species and the chemical composition of the carbonates are controlled primarily by the initial sedimentary facies of the host sediments and secondarily by the diagenetic evolution of pore water during burial based on the regular sequence and burial depth of precipitation of authigenic carbonates in a specific sedimentary facies three diagenetic stages of carbonates are proposed carbonates formed during stage i 2000 m are fe calcite and extremely high ca mg siderite the latter is exclusively in marine mudstones the supply of ca is partly from the alteration of silicates in the sediments at elevated burial temperatures after uplift calcite with low mg content precipitates from percolating groundwater and fills extensional cracks

evolution of an ancient coastal plain palaeosols interfluves and alluvial architecture in a sequence stratigraphic framework cenomanian dunvegan formation ne british columbia canada to date discussion of changes in alluvial style and in the character of palaeosols in relation to changes in accommodation and sediment supply on floodplains has primarily been from a conceptual standpoint few case studies are available against which to test ideas one hundred and thirty metres of non marine strata of the dunvegan formation were examined in 14 closely spaced sections in the canyon of the kiskatinaw river ne british columbia canada this site was located about 120 km inland from the transgressive limit of the contemporary marine shoreline and represents almost exclusively freshwater environments fluvial channels in the kiskatinaw river section are of two types small single storey very fine to fine grained sandstone ribbons with w t ratios 30 are interpreted as the deposits of meandering rivers filling incised valleys interchannel facies include the deposits of crevasse channels and splays lakes floodplains and palaeosols floodplain palaeosols consist of laterally heterogeneous simple palaeosol profiles and pedocomplexes similar to modern entisols inceptisols and hydromorphic soils interfluve sequence bounding palaeosols adjacent to incised valleys are laterally continuous up to 3 m thick and can be reliably identified using a combination of 1 stratigraphic position 2 field observations such as thickness structure colour degree of rooting and 3 micromorphological features such as evidence of bioturbation clay coatings ferruginous features and sphaerosiderite interfluve palaeosols are similar to modern alfisols and ultisols correlation of the local stratigraphic succession with the regional sequence stratigraphic framework based on 2340 well logs and 60 outcrop sections shows that the vertical changes in coastal plain character more coals and lakes vs more pedogenesis can be related to relatively high frequency base level cycles eustatic that are expressed as transgressive regressive marine cycles in downdip areas regional isopach maps show that these cycles were progressively overprinted and modified by an increasing rate of tectonic subsidence in the north and west the character of palaeosols developed on aggrading floodplains primarily reflects local sediment supply and drainage in contrast well developed interfluve palaeosols record pedogenesis during periods of reduced or negative accommodation base level fall vertical changes in floodplain palaeoenvironments and palaeosol types reflect changes in accommodation rate the detailed micromorphological analysis of interfluve palaeosols represents a powerful application of an under used technique for the recognition of key surfaces in the geological record this has broad implications for non marine sequence stratigraphy

oxygen isotopes in meteoric calcite cements as indicators of continental paleoclimate because meteoric water 18 o values decrease with decreasing ambient temperature and increasing latitude 18 o values of meteoric calcite cement should exhibit a similar relation with paleolatitude and be an indicator of continental paleotemperatures to test this we compiled isotopic and paleolatitude data for 20 meteoric cements and nine speleothems ranging in age from devonian to modern and in paleolatitude from 3 5 to 83 mean 18 o values for meteoric cements and speleothems both show the same negative correlation with paleolatitude the 18 o vs latitude trend for these carbonates is almost identical to that predicted for modern inland environments but differs from the trend for coastal environments this suggests that the ground water controlling the ultimate composition of meteoric cement is derived predominantly from inland recharge if it is assumed that the modern meteoric water 18 o vs temperature relation is valid for the past and that insignificant evaporation occurred prior to carbonate precipitation then coastal and inland paleotemperatures can be calculated from the 18 o values of meteoric calcite 18 o mcl and seawater 18 o sw by using the equations t coastal 13 3 32 6 0 231 0 0613 18 o mcl 18 o sw and t inland 17 8 16 2 0 572 0 1233 18 o mcl 18 o sw where t is temperature in c calcite precipitated from coastal meteoric water at temperatures between 0 and 25 c will exhibit a narrow range in 18 o 6 to 4 where 18 o sw 0 the 18 o of calcite precipitated from inland meteoric water will be sensitive to paleotemperature ranging from 14 to 5 where 18 o sw 0 for temperatures of 0 to 25 c

preservation of a paleo vertisol and an estimate of late mississippian paleoprecipitation abstract a late mississippian paleosol satisfying all of the morphological criteria required for classification of holocene vertisols provides quantitative paleoclimate information in addition to the now commonplace interpretation of precipitation seasonality based on the presence of vertic features paleoprecipitation was estimated using the empirical relationship between depth to pedogenic carbonate horizon in quaternary soils burial compaction erosional truncation and high paleoatmospheric co2 concentration all factors that complicate paleoprecipitation estimates are unusually well constrained for this paleosol allowing for 10 compaction the paleosol had a pre burial depth of 100 cm for the pedogenic carbonate horizon yielding a mean annual paleo precipitation estimate f 648 141 mm this is comparable to the mean annual precipitation for brownsville texas where similar soils are found today a dolomicrite crust developed in gilgai microlows is well preserved in the paleo vertisol higher late mississippian paleotemperatures and rates of evapotranspiration associated with a lower latitude paleogeography for central tennessee during the late mississippian may explain in part why holocene coastal vertisols in the brownsville region lack surficial crusts similar to that of the paleo vertisol we qualitatively define the late mississippian climate of central tennessee as semiarid

stratigraphic implications of meteoric sphaerosiderite 18o values in paleosols of the cretaceous albian boulder creek formation ne british columbia foothills canada abstract the md 80 08 coal exploration core from the albian boulder creek formation of northeastern british columbia contains 90 m of alluvial strata that underwent extensive pedogenic modification gleyed colors pedogenic slickensides clay coatings mottling sphaerosiderite and sedimentary pyrite characterize the paleosols the isotopic compositions of 30 sphaerosiderite bearing horizons commonly show trends of invariant 18o and variable 13c values equal area plots of 18o vs 13c were used to construct meteoric sphaerosiderite lines msls the msls indicate that meteoric groundwater compositions ranged from approximately 11o oo to 16o oo smow the sphaerosiderite 18o values indicate formation in shallow groundwaters predominantly recharged by local precipitation the sphaerosiderite isotopic compositions are a proxy record of mid cretaceous precipitation and are useful for quantifying changes in the hydrologic cycle during humid greenhouse periods micromorphology of a 1 15 meter interval 69 75 68 6 m with a 1 31o oo increase in the average 18o values records a polygenetic history of paleosol development the pedocomplex has a four stage developmental history characterized by 1 an initial well drained phase with wet dry cycles and relatively low baselevel 2 erosion baselevel rise and coarser grained sedimentation 3 saturated reducing soil conditions high baselevel with some marine influence on pedogenesis and 4 meteoric water dominated hydromorphic soil conditions high baselevel and sphaerosiderite precipitation the 18o excursion recorded through this interval reflects minor mixing of marine and meteoric groundwaters the modal abundance of pyrite and increased mg ca mg and mg fe cation ratios in the sphaerosiderites further substantiate marine influence on pedogenesis the alluvial section of the boulder creek formation is aggradational and several changes in baselevel recorded in the paleosols are interpreted to have been driven by minor parasequence scale changes in relative sea level

carbon dioxide in the paleozoic atmosphere evidence from carbon isotope compositions of pedogenic carbonate stable carbon isotope compositions of pedogenic carbonate occurring in three clay rich vertic paleosols within paleozoic red bed successions in central pennsylvania provide a record of past pedogenic environments and can be used to estimate co sub 2 pressure p sub co sub 2 of the paleozoic atmosphere the delta sup 13 c values of carbonate nodules from paleosols in the deltaic lower bloomsburg formation upper silurian reflect the contribution of carbon from marine groundwater or fossils coupled with low biological activity the delta sup 13 c values of carbonate rhizocretions from stratigraphically high paleosols in the bloomsburg formation and in the alluvial catskill upper devonian and mauch chunk upper mississippian formations suggest an extensive c sub 3 flora and significant contribution of atmospheric co sub 2 paleozoic atmospheric co sub 2 levels inferred from delta sup 13 c of pedogenic carbonate are significantly higher than present levels

systematic sequence scale controls on carbonate cementation in a siliciclastic sedimentary basin examples from upper cretaceous shallow marine deposits of utah and coloradao usa whilst the relationship between stratigraphic development and carbonate cementation within siliciclastic succession has been documented through a number case studies these studies have been generally restricted to observations upon individual sequences and or limited sub surface data in this paper long term 5 million years large scale 200 km stratigraphic controls on carbonate cementation patterns are documented from the upper cretaceous panther tongue member blackhawk formation and castlegate sandstone exposed in the book cliffs in utah and colorado usa together these comprise eight progradational wedges of sandstones which interfinger with the mancos shale deposited within the western interior seaway foreland basin petrographic analyses of ferroan dolomite cement bodies within these sandstone wedges show that the ferroan dolomite cements are all early relative to burial diagenesis within the host sandstones stable isotope analyses indicates that a significant meteoric component was present in precipitating fluids and this is consistent with the observation that cements are always present down dip of sequence boundaries and or leached whitecaps beneath coals in addition the lateral distribution of cement bodies increases consistently up succession from less than 5 km in extent in the older sequences to 30 km in extent in the youngest sequences these changes in distribution are in response to the increased progradation and increased and more aerially extensive sequence boundary development in younger sequences the implications of these data are that whilst localized spatial patterns of diagenesis and in particular carbonate cementation are predictable and controlled by the nature and presence of individual stratal surfaces systematic diagenetic alteration patterns are also present at the sedimentary basin scale and controlled by the nature of larger scale stratigraphic development and basin evolution this evolution may be driven by eustatic shifts or through tectonic or climatic driven base level shifts these observations allow an improved insight into the basin scale processes that control the macroscopic diagenetic properties of sedimentary successions and sub surface hydrocarbon reservoirs

micromorphology and stable isotope geochemistry of historical pedogenic siderite formed in pah contaminated alluvial clay soils tennessee u s a abstract alluvial clay soil samples from six boreholes advanced to depths of 400 450 cm top of limestone bedrock from the chattanooga coke plant ccp site were examined micromorphologically and geochemically in order to determine if pedogenic siderite feco3 was present and whether siderite occurrence was related to organic contaminant distribution samples from shallow depths were generally more heavily contaminated with polycyclic aromatic hydrocarbons pahs than those at greater depth the upper 1 m in most boreholes consisted of mixtures of anthropogenically remolded clay soil fill containing coal clinker cinder grains and limestone gravel most layers of coarse fill were impregnated with creosote and coal tar most undisturbed soil below 1 m depth consisted of highly structured clays exhibiting fine subangular blocky ped structures as well as redox related features pedogenic siderite was abundant in the upper 2 m of most cores and in demonstrably historical 100 years old soil matrices two morphologies were identified 1 sphaerosiderite crystal spherulites ranging from 10 to 200 m in diameter and 2 coccoid siderite comprising grape like clusters of crystals 5 20 m in diameter the siderite formed in both macropores and within fine grained clay matrices indicates development of localized anaerobic low eh conditions possibly due to microbial degradation of organic contaminants stable isotope compositions of the siderite have 13c values spanning over 25 7 to 18 vpdb indicating fractionation of dic by multiple microbial metabolic pathways but with relatively constant 18o values 4 8 0 66 vpdb defining a meteoric sphaerosiderite line msl calculated isotope equilibrium water 18o values from pedogenic siderites at the ccp site are from 1 to 5 per mil lighter than the groundwater 18o values that we estimate for the site if confirmed by field studies in progress this observation might call for a reevaluation of low temperature siderite water 18o fractionations investigations at the ccp site thus provide valuable information on the geochemical conditions under which siderite can form in modern soils and thus insight on controls on siderite formation in ancient soils

metallogeny of the large scale carboniferous karstic bauxite in the sanmenxia area southern part of the north china craton china abstract above two billion tons of bauxite were formed during the exposure of the north china craton ncc in 445 300 ma mineralogical geochemical and isotopic analyses of karstic bauxite deposits in the sanmenxia area situated within southern ncc were conducted to explore the genetic processes of carboniferous bauxite the bauxite contains three layers a lower fe bearing claystone layer a middle bauxite ore layer and an upper claystone layer fe bearing claystone is dominated by illite and hematite in the uplift and illite siderite and pyrite in the depression bauxite ore is composed of diaspore illite pyrite and anatase and the upper claystone consists of illite diaspore and anatase distinct pyrite 34s values 11 7 15 2 and 11 5 to 1 0 illite 87sr 86sr i 0 711917 0 713588 and 0 708000 0 711057 and end t 12 2 to 11 4 and 11 8 to 9 7 values and the immobile elemental ratios were obtained between the lower fe bearing claystone and upper bauxite ore and claystone together with chemistry of detrital rutile it is denoted the fe bearing claystone was formed from the underlying limestone whereas the bauxite ore and claystone were derived from both igneous rocks along craton margin and regional precambrian metamorphic rocks the visible microorganisms and wide development of framboidal pyrite with negative 34s within the bauxite ore provide evidences of microbial activity during bauxite formation bio leaching process after the deposition of allochthonous source materials caused the downward migration of ions al3 fe2 ti4 ree3 etc these ions encountered an alkaline and reducing condition in the karstic depression forming diaspore pyrite and anatase and ree enrichment at the bottom of bauxite ore this large input of raw materials warm and humid climate and microorganisms led to large scale bauxite formation in the ncc during late carboniferous

ground penetrating radar for high resolution mapping of soil and rock stratigraphy ground penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions the need to better understanding overburden conditions for activities such as geochemical sampling geotechnical investigations and placer exploration as well as the factors controlling groundwater flow has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible the areas of application for ground penetrating radar are diverse the method has been used successfully to map ice thickness water depth in lakes bedrock depth soil stratigraphy and water table depth it is also used to delineate rock fabric detect voids and identify karst features the effective application of the radar for the high resolution definition of soil stratigraphy and fractures in bedrock is highlighted the basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories one example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination the corroboration of the radar results by borehole investigations demonstrates the power and utility of the high resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes with the advent of new instrumentation and field procedures the routine application of the radar method is becoming economically viable and the method will see expanded use in the future

paleosols in shallow marine carbonate sequences abstract shallow water carbonate sequences in the geological record commonly exhibit numerous exposure surfaces reflecting emersion of sediment due to progradation processes and sealevel oscillations some ancient platform sequences contain hundreds of such surfaces associated with paleosols fossil soils typically calcretes a wide range of macro and microstructures are associated with these calcretes which are reviewed profile types and stages in profile development can be defined the nature of the exposure surface and associated paleosols can be used to identify the nature of the prevailing climate although hydromorphic effects related to marine flooding of the platforms can modify the paleosols a potentially important use of paleosols is to define the nature of sequence boundaries several studies have identified sets of paleosols with varying maturities reflecting changes in rates of accommodation space creation during sealevel rises and falls

middle cretaceous greenhouse hydrologic cycle of north america we present a paleolatitudinal precipitation reconstruction for the greenhouse setting of mid latitude north america based on the oxygen isotopic composition of sphaerosiderites found in middle cretaceous wetland paleosols our reconstructed middle cretaceous d 18 o values of precipitation are 4 less than values from comparable modern low elevation coastal settings free of monsoons the data fit a conceptual model in which the precipitation source for the eastern margin of the cretaceous western interior seaway of north america is an 18 o enriched oceanic coastal jet in this subtropical tropical setting midcretaceous precipitation rates are interpreted to range from 2500 to 4100 mm yr

measuring thaw depth beneath peat lined arctic streams using ground penetrating radar in arctic streams depth of thaw beneath the stream channel is likely a significant parameter controlling hyporheic zone hydrology and biogeochemical cycling as part of an interdisciplinary study of this system we conducted a field investigation to test the effectiveness of imaging substream permafrost using ground penetrating radar gpr we investigated three sites characterized by low energy water flow organic material lining the streambeds and water depths ranging from 0 2 to 2 m we acquired data using a 200 mhz pulsed radar system with the antennas mounted in the bottom of a small rubber boat that was pulled across the stream while triggering the radar at a constant rate we achieved excellent results at all three sites with a clear continuous image of the permafrost boundary both peripheral to and beneath the stream our results demonstrate that gpr can be an effective tool for measuring substream thaw depth copyright 2005 john wiley sons ltd

estimating the oxygen isotopic composition of equatorial precipitation during the mid cretaceous abstract recent studies utilize the oxygen isotopic composition of pedogenic carbonates siderite and calcite to evaluate empirically the global hydrologic cycle during the cretaceous pedogenic carbonates are used as a proxy for the isotopic composition of meteoric waters in order to estimate precipitation rates in the aptian albian via a mass balance model these modeling studies have previously been limited to mid latitude to high latitude data and thus a more extensive latitudinal data set is needed to produce a more globally constrained model this study provides an equatorial 2 s paleolatitude data set from pedogenic sphaerosiderites of the caballos formation from the upper magdalena valley colombia in addition macroscopic and microscopic morphological features of paleosols were used to identify ancient soil conditions the gleyed appearance and presence of sphaerosiderites suggest that soils were dominated by water saturated conditions with occasional incursions of marine influenced water resulting in pyrite precipitation this observation constrains the sampling sites to paleoelevations near sea level paleosols are interpreted to have been entisols inceptisols and ultisols similar to soils in coastal equatorial regions of modern colombia relatively invariant 18o values and more variable 13c values produce vertical trends in 13c vs 18o space called meteoric sphaerosiderite lines the average oxygen isotopic composition for these trends is 4 41 0 37 vpdb the average oxygen isotopic composition of meteoric waters precipitating the sphaerosiderites is estimated at 4 56 0 38 vsmow these are slightly more enriched than modern and modeled cretaceous estimates of equatorial precipitation 18o but are generally in agreement with expected oxygen isotopic compositions of precipitation for this paleolatitude

natural electromagnetism in the rhine graben summary together with experiments by differential geomagnetic soundings magnetotelluric soundings have been performed in the rhine graben the results of the former have been presented and discussed before we try to show that it is not necessary to call upon the notion of induction in surrounding areas to justify the characteristics of the observed anomalous magnetic fields theoretical calculations of these fields on structures defined by the interpretation of magnetotelluric sounds or by geological and other geophysical data agree very well with experimental data we conclude that magnetotelluric experiments and interpretations are valid as the rhine graben is a well known region allowing us to verify our interpretation

variations in permafrost thickness in response to changes in paleoclimate solutions to the stefan problem for the motion of the base of ice bearing permafrost in response to changes in paleoclimate were obtained using perturbation finite difference and finite element methods paleotemperature models were used to investigate the thickness response to compare solution methods to determine the current state of the permafrost and to determine constraints on the models the perturbation and finite difference methods used the approximation of linear temperature profiles while the finite element method did not there was a transient thickness response of about 41 kyr implying that paleotemperature records of greater length are needed for models and that the permafrost loses its memory of past conditions for much longer times faster thawing rates slower freezing rates and greater variations in thickness were found for the perturbation and finite difference solutions compared to the finite element solution these results appear to be caused by the simplifying assumptions in the former solutions a lag about 20 kyr exists between changes in surface temperature and thickness response and a small thermal offset is apparent in the finite element solution small asymmetries exist in the freezing and thawing rates and the thickness response paleotemperature models based on ice cores predict current permafrost thicknesses that are too large models with the long term mean surface temperature of permafrost within a few degrees of the current value of 11 c and with the last glacial period temperatures no more than 6 8 c lower are compatible with current prudhoe bay conditions these include models developed for east siberia from isotopic profiles in deep sea sediments and for barrow alaska modified for prudhoe bay these models predict that the permafrost thickness at prudhoe bay varied by about 10 or less 60 m over the last glacial cycle freezing and thawing rates were less than 6 mm yr 1 at present this permafrost should be near its long term equilibrium thickness and thawing at 1 mm yr 1

towards realistic aquifer models three dimensional georadar surveys of quaternary gravel deltas singen basin sw germany abstract understanding sedimentary heterogeneities has nowadays become crucial for sophisticated aquifer management the methods used so far for aquifer characterization e g pump test coring analysis cannot provide the needed resolution for a sufficient prediction of the subsurface properties e g sudicky 1986 this calls for the application of the outcrop analogue approach to aquifers e g macfarlan et al 1994 aigner 1995 in this project we used georadar ground penetrating radar or gpr to acquire the subsurface information for high resolution three dimensional images and radar facies mapping of glaciolacustrine delta sediments in the singen basin sw germany a three dimensional reconstruction of sedimentary heterogeneities for a detailed aquifer characterisation becomes possible by combining gpr profiling and outcrop information a case study is presented showing a complex three dimensional architecture of a quaternary gravel body consisting of the following three types of architectural elements 1 glaciolacustrine delta foresets 2 erosional surfaces with scour pool fills and 3 horizontal glaciofluvial gravel sheets although this seems a relatively simple architectural inventory the three dimensional georadar profiling shows considerable internal heterogeneities the radar data are interpreted following the seismic stratigraphic approach i e the delineation of radar facies types and of radar sequences the three dimensional heterogeneities are visualized by means of time slices 3 d block or chair diagrams or series of radar facies maps

the use of diagenetic signatures to distinguish marine from continental deposits in triassic jurassic sandstone reservoirs from the uk central graben abstract poor biostratigraphic control for some triassic jurassic successions in the north sea basin and sub basins necessitates the use of alternative correlation methods this study examines the use of diagenetic signatures to distinguish continenetal from marine sandstone successions triassic jurassic in the uk central graben the key diagenetic alterations encountered in these successions include kaolinitization of the framework grains and the development of sphaerosiderite and pyrite the 13 c v pdb values of siderite 8 1 to 8 5 and of ankerite 10 8 to 9 2 indicate a strong contribution of dissolved carbon from the decay of plant material in soil however marine water likely influenced diagenesis during periods of relative sea level rise by providing the dissolved sulfate so 4 2 required for the precipitation of pyrite the presence of diagenetic alterations such as kaolinitization of framework grains and cementation by sphaerosiderite could indicate that the sediments were deposited in an overall continental setting however the occurrence of pyrite and scattered grains of deep green colored glauconite suggests occasional marine influence such information on the changes of the diagenetic realm provides important clues for establishing a framework for stratigraphic correlations caution should be exercised when interpreting petrographic data as subsequent episodes of telodiagenesis can complicate petrographic interpretations

iron iii reduction in a low organic carbon brackish marine system abstract siderite rhizocretions are generally considered to be an indicator of fresh water conditions the presence of siderite rhizocretions with a marine 18o isotope signature in the rutland formation ketton u k seems to contradict this belief commonly in marine settings pyrite is more prevalent than siderite because of the high concentrations of sulfate in seawater the rutland formation is a fine grained mixed carbonate clastic succession with interbedded coals that was deposited in marginal marine conditions analysis of siderite revealed that it was chemically zoned predated pyrite and has an average 18o signature of 0 44 this siderite is interpreted as having precipitated during early diagenesis from brackish to marine porewaters containing low concentrations of bioavailable organic matter despite the porewaters being dominantly marine under conditions of restricted organic matter quality and or quantity fe iii reducing bacteria can outcompete sulfate reducing bacteria for the organic substrate resulting in the precipitation of siderite at the expense of pyrite

groundwater table fluctuations recorded in zonation of microbial siderites from end triassic strata in a terrestrial triassic jurassic boundary succession of southern sweden perfectly zoned sphaerosiderites are restricted to a specific sandy interval deposited during the end triassic event underlying and overlying this sand interval there are several other types of siderite micromorphologies i e poorly zoned sphaerosiderite spheroidal ellipsoid siderite spherical siderite and rhombohedral siderite siderite overgrowths occur mainly as rhombohedral crystals on perfectly zoned sphaerosiderite and as radiating fibrous crystals on spheroidal siderite concretionary sparry microspar and or micritic siderite cement postdate all of these micromorphologies the carbon isotope composition of the siderite measured by conventional mass spectrometry shows the characteristic broad span of data probably as a result of multiple stages of microbial activity sims secondary ion mass spectrometry revealed generally higher 13c values for the concretionary cement than the perfectly zoned sphaerosiderite spheroidal siderite and their overgrowths which marks a change in the carbon source during burial all the various siderite morphologies have almost identical oxygen isotope values reflecting the palaeo groundwater composition a pedogenic freshwater origin is supported by the trace element compositions of varying fe mn ratios and low mg contents fluctuating groundwater is the most likely explanation for uniform repeated siderite zones of varying fe mn ratios reflecting alternating physiochemical conditions and hostility to microbial life activity bacterially mediated siderite precipitation likely incorporated mn and other metal ions during conditions that are not favourable for the bacteria and continued with fe rich siderite precipitation as the physico chemical conditions changed into optimal conditions again reflecting the response to groundwater fluctuations

extensive carbonate cementation of fluvial sandstones an integrated outcrop and petrographic analysis from the upper cretaceous book cliffs utah abstract extensive large scale pervasive cementation in the form of cement bodies within fluvial strata has rarely been documented although fluvial strata commonly act as important hydrocarbon reservoirs as well as groundwater aquifers here we present outcrop petrographic and geochemical data for pervasive ferroan dolomite cement bodies up to 250 m in size from upper cretaceous desert member and castlegate sandstone fluvial strata exposed in the book cliffs in utah these cement bodies are present with coastal plain fluvial strata within both the desert and castlegate lowstand sandstones and are most abundant in the thin distal fluvial strata cement bodies are almost entirely absent in updip thicker fluvial strata petrographic observations suggest a predominantly early diagenetic timing to the mildly ferroan dolomite with a component of later burial origin 13 c values for the cement 4 8 to 5 7 v pdb suggest a marine derived source for the earliest phase with a burial organic matter source for later cement 18 o data 6 3 to 11 8 v pdb suggest precipitation from freshwater dominated fluids it is proposed here that dolomite was derived from leaching of detrital dolomite under lowstand coals and cementation took place in coastal aquifers experiencing mixed meteoric marine fluids as a result of base level fluctuations this data presented here shows that large cement bodies can be an important component within fluvial sandstones with a potentially significant impact upon both reservoir quality and fluid flow within reservoirs especially at the marine non marine interface

alluvial terraces and paleosols as indicators of early oligocene climate change john day formation oregon abstract flights of paleoterraces exposed in the painted hills area of central oregon record periods of alluvial cutting and filling that correspond with early oligocene climate changes the terraced interval is situated chronologically between two global climate steps the eocene oligocene boundary at 34 ma and the mid oligocene climatic transition at 30 ma the paleoterraces and associated paleosols are in the middle and upper big basin members of the john day formation and are bracketed by both 40ar 39ar age determinations and oligocene floral and faunal fossil assemblages the paleoterraces are defined by truncation surfaces that cut underlying alluvial strata are nlapped by paleosols and are mantled locally by colluvium influenced iron rich paleosols one well exposed truncation surface has a stepped geometry with nearly horizontal sections treads separated by steep sections risers with relief of 4 5 m the truncation surfaces represent episodes of incision of the overbank alluvium and the overlying disconformable paleosols mantling the surfaces represent periods of landscape stabilization following incision the strata as a whole can be grouped into three categories according to the degree of development of paleosols in the sequences these paleosol sequences can be interpreted in terms of climatic geomorphic fluvial response 1 rapidly deposited alluvium with weakly developed paleosols is interpreted to represent deposition during periods of rapid climate change during these periods the vegetation landscape system was in disequilibrium thereby causing accelerated soil erosion from the hinterland landscape which was accompanied by floodplain aggradation 2 slowly deposited alluvium with well developed clayey paleosols may indicate climatic optimum conditions when vegetation both suppressed soil erosion and enhanced sediment storage in hinterland soils 3 most of the alluvial st ata falls into a third category which consists of alternating moderately and weakly developed paleosols this alluvium is interpreted as fluvial deposition responding to a geomorphic system in dynamic equilibrium the largest terrace surface cuts into rapidly deposited alluvium with weak paleosol development and may represent a complex response incision feature associated with a preceding period of rapid alluviation a chronology for the alluvial cut and fill episodes is constructed based on stratigraphic relationships time estimates of paleosol development and 40ar 39ar age determinations time estimates from paleosols are made both by comparison of paleosols to modern soils from dated chronosequences and directly from 40ar 39ar age determinations of tuffs interbedded with complete sequences these methods allow estimation of sediment accumulation rates and of the timing and duration of aggradation and degradation episodes in the painted hills area the eocene oligocene boundary is marked by a truncation surface overlain by rapidly deposited alluvium this alluviation episode is estimated to have begun at about 33 2 ma a 10 m stack of red beds well developed clay rich and oxidized paleosols cap the before mentioned rapidly deposited strata and mark the top of the middle big basin member these paleosols are estimated to span the interval from 32 0 to 32 6 ma which corresponds to an early oligocene warming trend that immediately followed the eocene oligocene oi1 cooling event both recorded in marine isotopic data thus these red beds may represent an early oligocene climatic optimum in the pacific northwest

clay coatings from a modern soil chronosequence a tool for estimating the relative age of well drained paleosols abstract blue light optically stimulated luminescence osl dates obtained from upland and terrace soil profiles in southeastern mississippi have been used to generate a model for illuvial clay accumulation in deeply weathered subtropical soils e g ultisols the illuvial clays developed in upland vs alluvial terrace soils of southeastern mississippi are distinct in terms of thickness and total volume of translocated clay the coatings in the mississippi soils are also an analogue for clay coatings observed in mid cretaceous paleosols of north america many of the cretaceous paleosols had a polygenetic history the relative age of the well drained phase of pedogenic development characterized by illuvial clay accumulations may be estimated using the model generated from the mississippi soils as many of the mid cretaceous paleosols mark unconformities it would be beneficial to estimate the duration of the hiatuses three geomorphic surfaces characterize the landscape of southeastern mississippi uplands stream cut terraces and modern alluvium the present floodplain has poorly developed soils and lacks illuvial accumulations soils developing in the uplands have abundant and prominent illuvial clay coatings up to 2 mm thick while the terraces have minor clay coatings less than 1 mm thick

spatial variability of palaeosols across cretaceous interfluves in the dunvegan formation ne british columbia canada palaeohydrological palaeogeomorphological and stratigraphic implications a basic sedimentological and palaeopedological framework is now in place for non marine sequence models the variability of interfluve palaeosols has not however been systematically documented nor have the stratigraphic implications of that variability been incorporated into sequence models interfluve palaeosol variability in the deltaic dunvegan formation ne british columbia canada is investigated for which a detailed allostratigraphic and palaeogeographic framework has been developed based on abundant well 2300 logs and outcrop 60 sections control regionally extensive valley fills and interfluves have been mapped in coastal plain deposits over an area of about 50 000 km 2 this palaeogeographic framework permits interfluve surfaces exposed in outcrop to be located in terms of distance from the margins of coeval valleys the micromorphological geochemical and mineralogical characteristics of five representative sequence bounding palaeosols located from 250 m to more than 15 km from coeval valley margins are described these interfluve palaeosols are similar to modern alfisols and all record i aggradation on an alluvial coastal plain ii a subsequent static and or degradational phase related to valley incision nondeposition and soil thickening and iii a final aggradational phase related to valley filling and renewed sedimentation across the coastal plain within this overall template however variations in palaeosol thickness redoximorphic features illuvial clay content and geochemistry suggest developmental control by hydrological characteristics that were influenced by both the nature of the underlying alluvial sediments and distance from the valley margin the presence of mature interfluve palaeosols with complex developmental histories suggests that landscape dissection may have been related to terrace development associated with valley incision palaeosols closer to valley margins are thicker contain more illuvial clay and display characteristics suggesting better drained conditions relative to those palaeosols that developed further from valley margins subsequent deposition on interfluves also reflects distance from valleys with those sites close to valleys accumulating cumulic soils with evidence of brackish groundwater whereas far from valleys 10 15 km groundwater was fresh and clastic supply minimal encouraging peat formation variations in drainage and palaeotopography during landscape dissection resulted in different palaeosol development styles on interfluve surfaces that can be shown on the basis of physical correlation to have the same geomorphic age these observations support the concept of the soil forming interval as a basis for pedostratigraphic correlation in ancient terrestrial deposits palaeosol variability on interfluves is to be expected and recognition and documentation of this variability is an important prerequisite to palaeogeomorphological palaeoclimatic and sequence stratigraphic interpretations

paleopedology and paleoclimatic implications of late ordovician vertic paleosols juniata formation southern appalachians abstract claystone paleosols with abundant vertic features occur in upper ordovician ashgillian red beds of the juniata formation in the southern appalachians the beans gap claystone paleosol formed during late ordovician pedogenesis of estuarine and upper tidal flat mud deposits pedogenic processes were dominated by shrinking and swelling of clay in a subtropical to warm temperate paleolatitude 30 35 south paleoclimate characterized by a seasonal moisture deficit dry 4 8 months year large scale pedogenic slickensides are abundant and locally define pseudo anticline structures the predominance of sepic paleosol micro fabrics compares favorably with holocene vertisol micromorphology post pedogenic marine transgression resulted in erosion of the upper parts of paleosols followed by marine bioturbation and introduction of marine fluids changes in whole rock chemistry associated with early marine diagenesis include elevated na2o cao mgo mno and p2o5 in the preserved top of each paleosol reduction of fe3 to fe2 resulted in a decrease in fe2o3 and formation of drab halos around burrows the original smectitic mineralogy was converted to a well ordered 2m1 illite through progressive burial diagenesis

spherulitic siderites in the holocene coastal deposits of korea eastern yellow sea elemental and isotopic composition and depositional environment abstract siderite concretions are recovered from both freshwater unit ii and tidal unit i deposits in the holocene macrotidal flat of kyunggi bay west coast of korea siderites from both units show a spherulitic and well rounded texture and well developed equant rhombs on the external surfaces the size of the concretions in unit ii 50 150 m in diameter is normally larger than that in unit i 10 20 m the siderites in unit ii are chemically pure and highly enriched in fe whereas those of unit i are relatively impure and distinctly zoned demarcating high mn up to 69 1 mol in the core and high fe up to 75 9 mol in the margin within siderites of unit i substitution for fe by ca and mg reaches up to 20 3 mol mean 15 1 mol and 16 1 mol mean 12 6 mol respectively bulk 18 o values 0 7 to 1 3 peedee belemnite pdb for siderites in unit i are relatively higher than those 7 1 to 0 5 pdb in unit ii regardless of units siderite 13 c values 21 3 to 11 2 pdb are persistently low indicating microbially mediated precipitation at shallow burial depth extensive mn ca and mg substitution coupled with enrichment of 18 o in the siderites of unit i seems to reflect marine influence during the holocene transgression the occurrence of early diagenetic siderites provides supporting evidence on the depositional environment marine vs non marine of the holocene muddy coastal deposits of korea eastern yellow sea

very large plant and root traces from the early to middle devonian implications for early terrestrial ecosystems and atmospheric p co2 plant and root traces from the fort prevel member of the battery point formation late early devonian emsian gaspe bay quebec canada are larger and more complex than previously postulated for land plants of this time the traces are preserved as clay and silt lined casts in or near growth position and provide evidence that early vascular land plants achieved substantial stature 2 3 m and were capable of deep rooting to nearly 1 m the root traces and alluvial deposits in which they occur suggest increased landscape stabilization and root system and paleosol morphologies that were influenced by a water stressed episodically energetic environment early devonian plants of such large stature may have been partly responsible for initiation of a steep decline in atmospheric p co 2 through organic carbon burial and accelerated terrestrial weathering

recognition of interfluve sequence boundaries integrating paleopedology and sequence stratigraphy in shallow marine and coastal plain strata sequence boundaries are easily recognized at the base of incised valley fills between valleys however it is more difficult to recognize sequence boundaries where they are expressed as interfluve paleosols we suggest that interfluve paleosols can be most reliably identified using a combination of 1 stratigraphic position 2 field observations such as thickness structure color and degree of rooting and 3 micromorphological features such as bioturbation fabric clay coatings ferruginous features and siderite and barite only micromorphology permits recognition of temporal changes in drainage surface stability and protracted pauses in sedimentation that typify these surfaces this three part approach has been successfully employed to identify interfluve sequence bounding paleosols in the cenomanian dunvegan formation in alberta and british columbia canada

floodplain palaeosols of the cenomanian dunvegan formation alberta and british columbia canada micromorphology pedogenic processes and palaeoenvironmental implications

oxygen isotope evidence for high altitude snow in the laramide rocky mountains of north america during the late cretaceous and paleogene the 18 o values of river waters in late cretaceous and paleogene basins of alberta montana wyoming and colorado are calculated from the isotopic composition of unaltered aragonite mollusk fossils the isotopic composition of these river waters has significant implications for the uplift and climate history of the mountains surrounding the basins our data show that the 18 o values of river water varied dramatically ranging from 23 to 5 relative to vienna standard mean ocean water with an uncertainty of 2 close stratigraphic association of river deposits with very different isotopic values indicates two different water sources rainfall in the warm low elevation basins and snowfall in surrounding mountains the 18 o difference between basinal and highland precipitation suggests that local relief was similar to today9s on the order of 2 5 3 km seasonal variation in shell 18 o values also indicates that there are times when large snow fields in the maastrichtian and paleocene mountains of montana and wyoming survived summer melting and were multiannual features