evidence for increased latent heat transport during the cretaceous albian greenhouse warming quantitative estimates of increased heat transfer by atmospheric h2o vapor during the albian greenhouse warming suggest that the intensified hydrologic cycle played a greater role in warming high latitudes than at present and thus represents a viable alternative to oceanic heat transport sphaerosiderite d 18 o values in paleosols of the north american cretaceous western interior basin are a proxy for meteoric d 18 o values and massbalance modeling results suggest that albian precipitation rates exceeded modern rates at both mid and high latitudes comparison of modeled albian and modern precipitation minus evaporation values suggests amplification of the albian moisture deficit in the tropics and moisture surplus in the mid to high latitudes the tropical moisture deficit represents an average heat loss of 75 w m 2 at 108n paleolatitude at present 21 w m 2 the increased precipitation at higher latitudes implies an average heat gain of 83 w m 2 at 458n at present 23 w m 2 and of 19 w m 2 at 758n at present 4 w m 2 these estimates of increased poleward heat transfer by h2o vapor during the albian may help to explain the reduced equator to pole temperature gradients

dynamics of neptune s major cloud features abstract we used voyager 2 images of neptune to investigate the dynamics of the great dark spot gds the scooter the second dark spot ds2 and the south polar features spf relative to previous studies we covered a longer time base achieved more complete sampling of the available data and improved accuracy by using stars to correct navigation errors we tracked the gds 8 day shape oscillation for more than 2000 hr measuring amplitudes of 7 4 in longitude and 1 5 in latitude we found a surprisingly large increase in the mean latitudinal size of the gds from 8 in january 1989 to 17 in august during the same period we measured steady gds northward motion from 26 s to 17 s and found no evidence of the latitudinal limits we confirmed that the varying longitudinal drift rates of the gds and ds2 were simple functions of latitude that approximately match the zonal wind profile measurements of at least three cycles of the periodic motions of the ds2 defined a 36 day period and amplitudes of 2 4 in latitude and 47 5 in longitude relative to its mean drift longitude we found that the bright core of the ds2 varied in step with the ds2 latitudinal oscillation reaching a maximum area when the ds2 was furthest north a large increase in relative core brightness at high phase angles is consistent with forward scattering cloud particles we measured one cycle of a scooter longitudinal oscillation of 20 about its mean drift position with a period of 120 days but the scooter s latitudinal motions are too small and of the wrong frequency to be consistent with an advective model of the zonal motions we found that the highly variable spf formation region has the same mean longitudinal drift rate as the ds2 but an offset of 180 in longitude and a 20 difference in latitude the apparent synchronization of these widely separated and dramatically different features is unexplained coupling to the deep interior is ruled out by the significant difference between the radio and cloud periods observed motions of all features are described by empirical models valid over the voyager time period comparisons of voyager results with groundbased observations did not lead to conclusive constraints on the long term dynamics although much of the data seem to be consistent with a 5 8 year oscillation in gds latitude

unconventional shale systems a comparative study of the in source sweet spot developed in the lacustrine chang 7 shale and the marine barnett shale abstract the upper triassic chang 7 shale and the mississippian barnett shale two remarkable shale systems that are considered promising unconventional shale oil gas targets in china and the usa respectively have different kerogen types that formed under lacustrine and marine environments in this study seventy six and ninety seven drilled core samples were collected separately from the zhang 22 well ordos basin and the mesquite 1 well fort worth basin respectively for determining the hydrocarbon generation retention and migration behaviors as well as the intrasource fractionation in the two shale successions geochemical indications of potentially producible oil as indicated by the oil crossover effect and the tmax shift phenomenon as well as the geochemical and molecular compositions of retained hydrocarbon suggest two categories of intervals in the chang 7 and barnett shale systems namely the in source sweet spot and the generative unit oils retained in the in source sweet spot have migrated from the adjacent generative unit and have been subjected to stratigraphic fractionation over geological time these oils are proportionally rich in aliphatic fraction and moderate chain length moieties which significantly improve the fluid mobility and producibility the oil quality improved by fractionation the weak adsorptive affinity of oil to organic matter and the good shale frackability all provide promise for the exploration and production potential of shale oil from the chang 7 and the barnett shale systems

winds of neptune voyager observations of cloud motions high temporal and spatial resolution images acquired from voyager cameras have been used to measure cloud motions to improve the meridional profile of the zonal mean circulation on neptune a wide range of atmospheric periods between 12 and 21 hours is revealed by the average cloud motions consistent with the previous observations new observations have expanded latitudinal coverage improved the determination of streak motions especially near 30 n and added statistical weight to latitudes already covered by previous measurements both new and earlier observations have been subjected to quality control procedures to reduce dispersion caused by erroneous observations the resulting data set emphasizes short time intervals to maximize target recognition most reliable cloud targets last less than one neptune rotation many only a fraction of it a broad equatorial retrograde jet extends from approximately 50 s to at least 45 n the northernmost latitude at which discrete cloud features have been seen a relatively narrow prograde jet of at least 300 m s 1 is found near 70 s the wind observations have a high degree of variability some of which is due to variability of motions but at many latitudes it reflects observation errors arising from rapid evolution of neptune s clouds a bias observed in the measured meridional component is most likely due to a small discrepancy between the true rotation pole of neptune and the pole position used in the data reduction zonal motions and morphology suggest the global circulation to be symmetric about the equator

paleomagnetic test of the emperor fracture zone hypothesis late cretaceous paleomagnetic data from the pacific plate were used to test farrar and dixon s 1981 hypothesis that 1700 km of strike slip accumulated during the early tertiary along the emperor fracture zone system an 8000 km long nw se trending feature which consists mainly of the emperor trough the gardner seamounts and the line islands the data strongly disagree with this hypothesis instead the data are consistent with no motion having occurred between seafloor east of the emperor fracture zone and seafloor west of the emperor fracture zone

the barnett shale compositional fractionation associated with intraformational petroleum migration retention and expulsion abstract the marathon 1 mesquite well was drilled in hamilton county texas targeting the barnett shale with late oil window maturity combining a large suite of petrologic and high resolution organic geochemical analyses on 120 core samples we have been able to document qualitatively and quantitatively the effects of petroleum retention within and expulsion from five intervals within the barnett shale lithological heterogeneities control the composition and amount of retained fluids the sorption of oil by solid organic matter is important in all intervals applying empirical formulas we have been able to demonstrate not only that retention is primarily controlled by total organic carbon toc but also that the live or labile component rather than dead or inert carbon constitutes the most active sorptive sites additional retention in the micropores provided by biogenic microcrystalline quartz sponge spicules accounts for the sweet spot defined by an oil crossover in the 9 14 m 30 ft thick second interval the fluorescing oil occurring in the axial chamber of the sponge spicules and that sorbed on organic particles are together enriched in saturated hydrocarbons whereas the dispersed oil from the adjacent interval 3 is depleted in this compound class mass balance calculations reveal that short distance migration of petroleum into this reservoir interval second fractionates the generated oil into a higher quality oil by preferential retention in the order polar compounds aromatic hydrocarbons saturated hydrocarbons within the underlying organic matter and clay rich third interval source unit furthermore molecular fractionation i e a preferential expulsion of lower molecular weight hydrocarbons n alkanes could be calculated an additional practical result for source rock assessment is that corrected s2 petroleum generated by pyrolysis and toc values should be calculated by combining rock eval pyrolysis data on whole rocks and rocks following soxhlet extraction using parameters based on unextracted rock only the expulsion of petroleum is systematically overestimated and the degree of kerogen conversion is therefore concomitantly underestimated

phanerozoic atmospheric co2 change evaluating geochemical and paleobiological approaches abstract the theory and use of geochemical modeling of the long term carbon cycle and four paleo pco 2 proxies are reviewed and discussed in order to discern the best applications for each method geochemical models provide pco 2 predictions for the entire phanerozoic but most existing models present 5 10 m y means and so often do not resolve short term excursions error estimates based on sensitivity analyses range from 75 200 ppmv for the tertiary to as much as 3000 ppmv during the early paleozoic the 13 c of pedogenic carbonates provide the best proxy based pco 2 estimates for the pre tertiary with error estimates ranging from 500 1000 ppmv pre devonian estimates should be treated cautiously error estimates for tertiary reconstructions via this proxy are higher than other proxies and models 400 500 ppmv and should not be solely relied upon we also show the importance of measuring the 13 c of coexisting organic matter instead of inferring its value from marine carbonates the 13 c of the organic remains of phytoplankton from sediment cores provide high temporal resolution up to 10 3 10 4 year high precision 25 100 ppmv for the tertiary to 150 200 ppmv for the cretaceous pco 2 estimates that can be near continuous for most of the tertiary its high temporal resolution and availability of continuous sequences is advantageous for studies aiming to discern short term excursions this method however must correct for changes in growth rate and oxygen level at elevated pco 2 750 1250 ppmv this proxy loses its sensitivity and is not useful the stomatal density and stomatal index of land plants also provide high temporal resolution 2 year high precision 10 40 ppmv for the tertiary and possibly cretaceous pco 2 estimates and so also is ideal for discerning short term excursions unfortunately this proxy also loses sensitivity at some level of pco 2 above 350 ppmv which currently is largely undetermined our analysis of the recently developed 11 b technique shows that it currently is not yet well constrained most importantly it requires the assumption that the boron isotopic composition of the ocean remains nearly constant through time in addition it assumes that there are no biological or temperature effects and that diagenetic alteration of the boron isotopic composition does not occur a fifth co 2 proxy based on the redox chemistry of marine cerium has several fundamental flaws and is not discussed in detail here

timing of early angiosperm radiation recalibrating the classical succession new stratigraphically controlled pollen data from the late early cretaceous of portugal allow a recalibration of the classical continental succession of the potomac group usa which has long been used to demonstrate the gradual morphological changes of angiosperm leaves and pollen the portuguese record represents the best dated succession of angiosperm pollen assemblages of the interval between the late barremian and the mid albian comparison of the angiosperm pollen record of the potomac group with the pollen assemblages from portugal and with other independently dated records indicates that the distinct differences in the angiosperm pollen assemblages between the three formations of this group the patuxent formation arundel clay formation and patapsco formation are related to discontinuities our revised age model for the potomac group implies a major discontinuity between the arundel clay of early albian age and the patapsco formation of mid albian early cenomanian age the portuguese record reveals a so far undocumented radiation phase of angiosperms within the early aptian to mid albian in which monocolpate angiosperm pollen of monocot and or magnoliid affinity appear as a highly diversified group these new findings imply that the onset of the radiation of monocots magnoliids preceded the radiation of eudicots by at least 10 ma

equation for compaction of paleosols due to burial existing empirically derived compaction curves for marine sediments fail to estimate the compaction of paleosols flood plain sediments and peats as indicated by deformation of clastic dikes dinosaur footprints and sandstone paleochannels yet compaction estimates are vital to reconstructing paleoclimate and geochemical profiles of paleosols to modeling sediment accumulation rates of nonmarine rocks and to tectonic flexural modeling of molasse facies this paper presents a compaction equation and physically derived constants that make geologically realistic estimates of compaction of paleosols and other nonmarine sediments a protocol for the application of the equation is suggested that would allow the following equation to solve for burial compaction c as a fraction of original thickness given depth of burial d in km as c s i f e d k 1 this equation can be applied to nonmarine sedimentary rocks or paleosols given appropriate empirical data on the physical constants in the equation such as initial solidity s i initial porosity f and the corresponding curve fitting constant k data on physical constants useful for this equation are compiled here for a range of paleosol and nonmarine sediment types

phanerozoic atmospheric oxygen new results using the geocarbsulf model modifications of the geocarbsulf model for phanerozoic atmospheric oxygen have been made to account for new carbon isotopic data reconsideration of the fractionation of carbon isotopes between carbonate and organic matter deposited in sediments and different rates of weathering of volcanic rocks versus granitic rocks results indicate distinctly higher o2 values than geocarbsulf for the mesozoic and cenozoic lack of an appreciable drop in o2 below 15 percent at any time and a small late cenozoic decline of o2 to the present

distal alluvial deposits in a foreland basin setting the lower freshwater molasse lower miocene switzerland sedimentology architecture and palaeosols the lower freshwater molasse untere susswasser molasse crops out over a wide area of the swiss molasse basin coarse grained alluvial fan conglomerates dominate in proximal basin areas along the alpine front these conglomerates pass northwards into sandstones and mudstones of an extensive northeastward draining meandering river system which ran parallel to the basin axis sedimentological study of outcrops quarry exposures and boreholes in the basal miocene aquitanian has permitted detailed facies analysis of this distal alluvial sequence the distal aquitanian is made up of distinct architectural elements characterized by their geometries and sedimentary structures each may be assigned to a particular depositional setting meander belt levees crevasse channels and splays overbank fines and palaeosols and lacustrine meander belt sandstones were deposited in mixed load channels with a dominant bedload component sandstones commonly comprise amalgamated and locally stacked ribbon bodies 2 15 m thick and 150 1500 m wide interbedded rippled laminated and mottled fine grained levee sandstones and siltstones form lenticular packages up to 3 m thick and 30 100 m across small scale crevasse channel sandstones 2 4 m thick and 5 10 m across pass laterally into metre scale medium to fine grained crevasse sandstone sheets rare laminated lacustrine siltstones occur only in the north east part of the basin floodplain mudstones and marls make up the remainder of the succession these display a variety of pedogenic features recording cyclical palaeosol development palaeosols show strong variations in morphology and maturity both laterally across the floodplain and downstream along the basin axis reflecting local variation in aggradation rate associated with proximity to alluvial channel courses as well as regional variation in subsidence and floodplain drainage analysis of the organization and distribution of the various sediment bodies permits reconstruction of the fluvial system and allows development of a model for the sedimentary architecture of the lower freshwater molasse in the study area integration of palaeosol studies into a well defined architectural framework assists recognition of areal facies belts and may aid location of sand prone sequences in the subsurface

gondwanan late jurassic and cretaceous palaeosurfaces of the australian craton abstract cretaceous and especially early cretaceous marine transgressions played an important part in the evolution of the australian landscape they covered at least 40 of the present australian craton and about 45 of the entire present continent in so doing they preserved in unconformity extensive areas of the pre existing or gondwana landscape though substantial gondwana elements have been ehumed at the margins of the depositional basins as a result of the cainozoic stripping of the sedimentary cover clear examples are demonstrated in the isa highlands the peake and davenport ranges and the northermost flinders ranges the basinal areas subsided under the weight of water and sediment while adjacent land areas were uplifted flexure continentale or randschwelle those that were already of low relief were dissected and regoliths were eroded but substantial areas of the gondwana plains in etch form were preserved on divides as in the gawler and hamersley ranges others were reduced to low relief by rivers graded to cretaceous shorelines as in the southern and central flinders ranges elsewhere the gondwana landscapes were preserved more or less intact as in the western yilgarn craton the mt lofty ranges and possibly the higher ridges of the macdonnell ranges the nature of the gondwana landscape varied according to structure but inselberg landscapes were widely developed and have been exhumed for instance in the western pilbara and in the eastern musgrave block kulgera region the gondwana landscape was already complex with stratigraphic conditions suitable for the exhumation of archaean preterozoic and cambrian forms for instance already in place re exposure later took place so that very old elements form integral parts of the present landscape exhumed gondwana landscapes have been preserved by burial and the stripping of some of the etch forms may have taken place in the later cainozoic so that their survival poses few difficulties other etch surfaces like those of the gawler and the hamersley ranges demonstrably were stripped in the early cretaceous and eocene respectively and they like epigene earliest tertiary and mesozoic features call for explanation various factors like resistant bedrock unequal erosion surfaces which stand high and dry interior situation and reinforcement effects go some way to relieving though they do not resolve the problem

a study of the holzener asphaltkalk northern germany observations regarding the distribution composition and origin of organic matter in an exhumed petroleum reservoir abstract the holzener asphalkalk deposit is located on the southwestern flank of the hils syncline northern germany it consists of a series of kimmeridgian portlandian bitumen impregnated limestones cumulative thickness of nearly 200 m overlain unconformably by neocomian claystones and underlain by older jurassic and triassic sediments the most bitumen rich limestone layers have been extensively mined with the result that there is three dimensional access to what is probably an exhumed series of stacked petroleum reservoirs geochemical petrological and petrophysical techniques were used to gain some insight into the distribution and the source of the organic matter in two of the 13 layers of the deposit most disseminated organic matter was found to be soluble in organic solvents and rich in non hydrocarbons its distribution appears to be controlled by ooid versus carbonate matrix abundances the occurrence of fractures and degree of impregnation small meso to micro pores have high bitumen saturations whereas large pores meso to macro have much lower saturations mature petroleum is thought to have once filled all pores but alteration has probably removed as much as 85 of it mainly from the large pores regional geochemical considerations pyrolysis and stable carbon isotope data indicate that the original petroleum was most probably derived from the underlying posidonia shale toarcian source rock asphaltene pyrolysis data indicate that an algal lacustrine co source might have also contributed to the deposit

basin scale changes in floodplain paleosols implications for interpreting alluvial architecture abstract floodplain paleosols in time equivalent strata of the willwood for mation differ in terms of paleodrainage and degree of pedogenic development ancient soils were more poorly drained and more strongly developed in one area compared to a second area about 45 km away this difference in drainage is attributed to parent material the more poorly drained paleosols formed in an area with less permeable clay rich floodplain deposits in the stratigraphic interval that accumulated more slowly paleosols are more strongly developed less numerous and thicker than in the more rapidly accumulating stratigraphic interval these differences are attributed not only to different sediment accumulation rates which are commonly considered to control the degree of ped ogenic development but also to differences in avulsion frequency a simple model is offered to show how paleosols change with varying basin subsidence rates and the relationship between avulsion frequency and accumulation rate when avulsion frequency increases more rapidly than sediment accumulation rate an increase in subsidence rate causes strongly developed paleosols to be overlain by a stratigraphic interval with paleosols that are less well developed thinner and more densely spaced when avulsion frequency is not related to accumulation rate as early models of alluvial architecture assumed an increase in subsidence rate produces a stratigraphic section in which strongly developed paleosols are overlain by paleosols that are less well developed thicker and more widely spaced study of the thickness and degree of development of floodplain paleosols can be used together with more traditional studies of alluvial architecture to provide a clearer understanding of the factors that influenced the stratigraphic architecture in a particular alluvial basin

past co2 changes and tropical sea surface temperatures the relationship between past co2 variations and tropical climate change on time scales of millions of years is reviewed explanations for cretaceous and early cenozoic climate change often involve higher atmospheric co2 levels climate models predict that such increases should have been associated with warmer tropical sea surface temperatures ssts however sparse mid cretaceous 18o based sst estimates from low latitude calcareous plankton are 1 0 1 5 heavier than predicted initial evaluations indicate that changes in salinity may not alleviate model data discrepancies for calcareous 18o and that interpretation of altered latitudinal 18o gradients in terms of increased poleward heat transport due to warm saline bottom water wsbw formation would require very large levels of wsbw production at least 60 sv calcareous 18o records may not always record true sst patterns as 18o analyses from phosphatic groups which are less sensitive to diagenesis indicate ssts 5 c higher this latter conclusion is supported by a number of other fossil groups which indicate temperatures warmer than those estimated from calcareous 18o in order to more rigorously test the paleo co2 hypothesis and indeed the models used to forecast future climates it is desirable to intensify investigations of past climate change in low latitudes in order to determine whether these preliminary conclusions stand the test of further scrutiny

late cretaceous and paleogene tectonic evolution of the north pacific ocean the late cretaceous history of the northern pacific ocean has not been adequately deciphered largely because a major plate reorganization occurred during the cretaceous magnetic quiet interval using primary data to reconstruct plate motions from fracture zone trends and late cretaceous seafloor spreading magnetic anomalies allows formulation of a reasonable sequence of events that accounts for all the geologic features of that region especially the emperor and chinook troughs the primary event in our reconstruction is the subduction of the old northwest pacific triple junction new relative plate motions imposed by formation of convergent boundaries along both the northern pacific and farallon plates caused the farallon plate to crack this subdivision occurred 82 m y ago and resulted in the formation of the kula and chinook plates the chinook plate was bounded on the north by the chinook kula ridge the western arm of the great magnetic bight on the west by the southern emperor trough a slowly spreading rift valley on the south by the mendocino transform and on the east by the chinook farallon ridge the northern emperor trough formed the initial western boundary of the kula plate from 82 m y ago to 50 m y ago this configuration was stable the chinook plate expanded the chinook kula ridge migrated north and the kula plate was subducted with the subduction of this ridge the chinook plate adhered to the pacific plate and the pacific farallon ridge became the north south trending feature reflected by anomalies 22 and younger this reconstruction obviates the awkward late cretaceous shifting of triple junctions found in other proposed histories and provides reasonable explanations for the several structural features of the region to achieve closure of vector triangles representing the relative late cretaceous plate motions some extension must occur presumably across the eastern mendocino fracture zone between the northern and southern portions of the farallon plate these two plates apparently were independent units between 105 and 50 m y ago the initiation and cessation of rapid north farallon north american convergence 82 and 50 m y ago may have determined the nature and duration of the laramide orogeny

the terrace like feature in the mid continental slope region off trivandrum and a plausible model for india madagascar juxtaposition in immediate pre drift scenario abstract bathymetry of the southwestern continental margin of india reveals the presence of an anomalous terrace like feature in the mid continental slope region off trivandrum the genesis of this terrace of large areal extent 9000 sq km is yet to be established based on exercises with several existing paleogeographic reconstruction models and updated compilation of identified offshore tectonic elements this study attempts to identify a plausible model of india madagascar juxtaposition in immediate pre drift scenario which provides idea about genesis of this terrace it is inferred that the terrace off trivandrum and an anomalous bathymetric notch located in the northern madagascar ridge are conjugate features related to india madagascar separation and the rifted and sheared segments of the pre drift plate boundary have shaped their outlines the drifting of india from madagascar is suggested to have commenced at about 86 5 ma

petroleum source maturity alteration and mixing in the southwestern barents sea new insights from geochemical and isotope data the hammerfest basin hb is an important area for petroleum exploration in the southwestern norwegian barents sea this contribution is aimed to characterize oils and condensates hosted in triassic and jurassic reservoirs establish genetic relationships and to assess maturity mixing and petroleum alteration processes the research was based on geochemical as well as bulk and compound specific stable carbon and hydrogen isotope analyses of oil and condensate samples from all major fields and discoveries in the hb including extracts from jurassic and triassic source rocks interpretations of light hydrocarbon composition and isotope data clearly identify four main petroleum groups affected by microbial degradation water washing evaporative fractionation and high thermal maturity level based on polycyclic aromatic hydrocarbons pahs marine and higher plant derived biomarkers and carbon isotopic composition 13c of individual petroleum hydrocarbons four petroleum families i iv are recognized in the hb and a distinction can be made among oils and condensates from different stratigraphic levels and sectors of the basin most oils and condensates from the hb consist of mixtures with small maturity variations however oils from middle triassic reservoirs in the goliat field showed larger maturity variations according to biomarker pah and light hydrocarbon maturity ratios in the hb geochemical and isotopic data allowed unraveling mixtures of hydrocarbons derived mainly from jurassic triassic and paleozoic source rocks

unraveling petroleum mixtures from the south viking graben north sea a study based on δ13c of individual hydrocarbons and molecular data abstract mixtures of compositionally different petroleum occur in the norwegian north sea one of the world s major oil producing regions the objective of the present contribution was to appraise the source maturity in reservoir mixing and alteration processes in a set of condensate and oil samples covering the main producing areas in the south viking graben svg furthermore this study focused on unraveling complex mixtures of petroleum and quantifying mixing ratios of hydrocarbons generated from jurassic source rocks the present research was based on a multiparameter approach that comprised the molecular composition of light hydrocarbons and heterocyclic and polycyclic aromatic compounds as well as the 13c of individual hydrocarbons in oils condensates and upper and middle jurassic source rock extracts from the svg according to the relative contribution of oils from type iii kerogen rich source rocks seven populations a g of mixed petroleum were identified by combining source related ratios of heterocyclic and non heterocyclic aromatic hydrocarbons and 13c values of n alkanes pristane pr and phytane ph the heterocyclic and polycyclic aromatic hydrocarbons provided a useful means to discriminate mixed hydrocarbons from source rocks of distinct organic matter type depositional environment and lithology in the svg the 13c enrichments of c10 c14 n alkanes and pr and ph were good indicators of the scale of the terrigenous source contribution and allowed quantitative determination of the proportions of jurassic source contributions enriched in type ii and type iii kerogens in complex petroleum mixtures from the southern part of the svg

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

nonmarine sequence stratigraphy updip expression of sequence boundaries and systems tracts in a high resolution framework cenomanian dunvegan formation alberta foreland basin canada ten allomembers labeled j a have been mapped in the deltaic dunvegan formation using 2340 wells and 63 outcrop sections each allomember spans about 200 k y is bounded by regional transgressive surfaces and consists of 3 10 component shingles apparently of autogenic origin allomembers h e are discussed in this article their internal stacking patterns and bounding surfaces permit interpretation as depositional sequences sequences h f have a sigmoidal prismatic geometry downlap to the southeast and thin northwest onto the coastal plain no differential thickening exists toward the orogen in the southwest in contrast sequence e thickens markedly toward the northwest the tabular geometry of sequences h f suggests accommodation was controlled by sea level change whereas the wedge geometry of sequence e suggests significant tectonic tilting subaerial unconformities that bound valleys and extend onto adjacent interfluve paleosols can be traced 120 330 km updip into outcrop the base of each sequence is characterized by shoreline backstep of 80 150 km transgressive and highstand shingles in each sequence comprise marine deltaic deposits that pass landward into coastal plain strata falling stage shingles offlap seaward with little or no nonmarine equivalents updip whereas lowstand shingles show renewed coastal onlap in outcrop three nonmarine systems tracts are recognized 1 a channel dominated low accommodation systems tract fills valleys up to 35 m deep and is equivalent to the early transgressive systems tract begin page 1968 2 a lacustrine dominated high accommodation systems tract comprises mudstone enclosing ribbon channel sandstones blankets interfluves and forms the bulk of each sequence it is equivalent to late transgressive and early highstand systems tracts 3 a paleosol dominated low accommodation systems tract occupies the upper part of each sequence and is capped by the sequence boundary it is equivalent to the late highstand systems tract sequence bounding interfluve paleosols represent tens of thousands of years of pedogenesis related to slow aggradation followed by fluvial entrenchment and clastic bypass and represent the late highstand falling stage lowstand and early transgressive systems tracts coastal plain deposits record only part perhaps

lower to mid cretaceous sequence stratigraphy and characterization of co2 storage potential in the mid atlantic u s coastal plain abstract the mid atlantic u s coastal plain new jersey delaware maryland and northern virginia contains thick 500 m mid cretaceous sand sandstone reservoirs confined by thick clay shale confining units and thus has high potential for storage of co 2 captured from nearby point sources the predictability of the continuity of the reservoir and confining units can be improved by applying principles of sequence stratigraphy including integration of lithostratigraphy biostratigraphy paleoenvironmental proxies and a novel application of fluvial aggradation cycles facs we evaluate the storage and confinement potential for the lower cretaceous waste gate formation and mid cretaceous potomac formation group in new jersey and maryland which we divide into three major reservoirs waste gate potomac unit i potomac unit ii and potomac unit iii we use new core data to ground truth well logs and paleoenvironmental changes sequence stratigraphic stacking patterns including facs and pollen biostratigraphy to update previous well log correlations in new jersey and extend these correlations into deep holes in maryland while individual sand beds are typically local in extent zones of sands are broadly correlative over distances of 60 km these regionally traceable sand prone zones should be useful for carbon storage cenomanian potomac unit iii sands are relatively thick 70 m in new jersey but generally thin average of 50 m into maryland they are near the updip limit for supercritical storage 800 m in new jersey and maryland and may not be suitable due to updip migration above the supercritical level potomac unit ii sands albian pollen zone ii appear to be discontinuous and less suitable in both states potomac unit i aptian pollen zone i and waste gate formation sands early aptian to berriasian pre pollen zone i are relatively thick 88 223 m and 81 288 m respectively and confined in new jersey and appear to be widespread and continuous the updip confinement of this reservoir in maryland is less certain volume storage estimates for the potomac i waste gate in the mid atlantic coastal plain are 8 4 33 5 gt co 2 adequate to store co 2 captured from 24 95 gw of natural gas generation for a century

the formation of inertinite rich peats in the mid cretaceous gates formation implications for the interpretation of mid albian history of paleowildfire abstract image analysis and standard point count petrographic data are used to interpret the amount source and variation of inertinite in coal seams of the mid cretaceous gates formation rocky mountain foothills northeastern british columbia inertinite on average is abundant between 40 60 by seam by volume and higher in some zones and within seams fluctuates cyclically the inertinite is interpreted to be almost exclusively fire derived suggesting that fire was a relatively common occurrence in the original peat forming wetlands inertinite enrichment in the gates coals appears to have resulted from preferential destruction of vitrinite precursors by either low temperature decomposition processes or burning rather than by formation of inertinite by a microbial process the position of the gates formation depositional setting east of the rising canadian cordillera is interpreted to have resulted in overall drier conditions in the region and periodic drought in the wetland settings cyclic variation in inertinite vitrinite composition within some of the seams is primarily attributed to climatic variations although variation in subsidence rates could also have been responsible

onshore offshore correlations of cretaceous fluvial deltaic sequences southern baltimore canyon trough we evaluate cretaceous depositional sequences on approximately 4400 km 2700 mi of newly released multichannel seismic profiles and five wells on the continental shelf in the southern baltimore canyon trough and tie the data to three wells drilled onshore in the maryland coastal plain seismic geometries coupled with facies and biostratigraphy from the wells are used to delineate mid cretaceous aptian turonian depositional sequences and paleogeography beneath these sequences 400 1000 m 1300 3300 ft of lower cretaceous sedimentary rocks underlie the modern shelf they thicken along strike to the southwest implying a southern sediment source aptian to cenomanian sediments were deposited in shelf to nearshore settings a landward movement of the depocenter and a shift toward facies indicative of deeper paleodepths marks a 107 yr mid cretaceous transgression within which we identify five sequences a composite maximum flooding surface mfs within the uppermost of these retrogradational units is associated with the cenomanian turonian boundary and ocean anoxic event 2 shingled lower turonian seismic reflections prograde across the outer shelf downlapping onto the composite mfs and are truncated by a mid turonian sequence boundary the upper cretaceous section thickens seaward and along strike to the northeast implying a northern source and little late cretaceous accommodation beneath the modern shelf mid cretaceous strata offshore maryland are likely sand prone considering their proximity to the correlative fluvial facies of the onshore potomac group these potential reservoir sands are capped by regional confining units generated by 107 yr global mean sea level flooding events and are excellent targets for supercritical carbon storage

classification of paleosols despite increased interest in paleosols during the past decade no satisfactory classification is in current use presented here is a largely descriptive classification system that utilizes those pedogenic features that have the highest preservation potential in the rock record emphasized in the classification are morphological and mineralogical features that are easily recognizable in the field and through the petrographic microscope the classification is based on evaluation of the relative prominence in a paleosol of six pedogenic features or processes organic matter content horizonation redox conditions in situ mineral alteration illuviation of insoluble minerals compounds and accumulation of soluble minerals the most prominent of these six features processes provides the key to classifying a paleosol into one of nine orders four of the order names are borrowed from soil taxonomy histosol spodosol oxisol vertisol whereas the other five order names are presented here for the first time calcisol gypsisol gleysol argillisol protosol the orders may be preceded by one or more subordinate modifiers that describe other important features of the paleosol the classification is relatively easy to apply to the rock record and should enhance communication and aid in the standardization of terminology

integration of channel and floodplain suites i developmental sequence and lateral relations of alluvial paleosols abstract the lower eocene willwood formation of the bighorn basin northwest wyoming consists of about 770 m of alluvial rocks that exhibit extensive mechanical and geochemical modifications resulting from eocene pedogenesis willwood paleosols vary considerably in their relative degrees of maturity maturity is defined as stage of development as a function of the amount of time required to form five arbitrary stages are proposed to distinguish these soils of different maturities in the willwood formation stage 1 soils the least mature are entisols stage 2 and stage 3 soils are intermediate in maturity and are probably alfisols and stage 4 and stage 5 soils the most mature are spodosols these stages are not only time progressive elements of an in situ maturation sequence for w llwood soil formation but in the lateral dimension they are also usually distributed sequentially study of willwood paleosols indicates that an inverse relationship exists between soil maturity and short term sediment accumulation rate the least mature willwood paleosols formed in areas of relatively high net rates of sediment accumulation on 1 channel levee and crevasse splay sediments of the proximal alluvial ridge and 2 deposits filling large and small paleovalleys formed by major episodes of gullying lowered baselevels in contrast the fine grained sediments of the distal floodplain where net sediment accumulation rates were relatively low experienced development of much more mature soils soils of intermediate maturities occur in the order of their stage on intervening proximal floodplain and distal alluvial ridge sediments adjacent bodies of sedimentary rock that differ in their ancient soil properties because of distance from areas of relatively high sediment accumulation are denoted by the new term pedofacies the remarkable sequence of paleosols in the willwood formation clearly illustrates several important principles of soil sediment interrelationships in aggrading alluvial systems that have broad application to other deposits this is especially true in view of the widespread distribution of paleosols in nearly all ancient fluvial rocks further study of willwood paleosols will not only enable precise lateral correlation of coeval alluvial sediments and thereby fluvial sedimentary events from the distal to the proximal realms of the floodplain but will also contribute to increasingly informative evaluations of the nature tempo and mode of alluvial succession

organic geochemical signals of freshwater dynamics controlling salinity stratification in organic rich shales in the lower permian irati formation parana basin brazil abstract the lower permian irati formation in the northeastern and central eastern parana basin southern brazil was investigated in terms of bulk and molecular organic geochemistry in order to enlighten the complex depositional paleoenvironment during deposition of irati black shales the geochemical data reflect temporal and spatial variations of freshwater incursions promoting salinity stratification and high primary productivity in surface waters with the establishment of photic zone euxinia overall highly concentrated c17 long chain alkylnaphthalenes point to algal blooms as a result of freshwater inflows into the irati sea mostly in the central eastern basin segment and resemble concentration variations of pristane phytane and nc17 the freshwater inflows were also retraced by increasing chroman ratios toward the top of the investigated units along with the general decrease of further palaeosalinity indicators e g gammacerane tetracyclic c24 carotane and the herein suggested carotane and lexane indexes the existence of a water column stratification promoting organic matter preservation is supported by the detection of tetrahydrophenanthrene at high concentrations in addition to the known prominent occurrence of gammacerane the detection of c10 to c31 aryl isoprenoids in addition to c16 and c18 pseudohomologue aryl isoprenoids points to the presence of photic zone euxinia in general samples from the central eastern basin were deposited in a deeper marine setting with lower salinity than samples from the northeastern basin which displays signals of a shallower marine environment with reducing bottom water conditions both deposited under freshwater influxes

comprehensive geochemical correlation between surface and subsurface hydrocarbon occurrences in the batman mardin şirnak area se turkey abstract southeast turkey is the main oil producing region of the country located at the northwestern part of the zagros basin in this study we investigated the geochemical characteristics of both surface and subsurface hydrocarbon occurrences in the batman mardin irnak area in southeast turkey to determine whether a genetic relationship exists between the two for this thirty solid bitumens from twenty two different veins along with ten heavy oils and thirteen oil seepage samples from nearby oilfields and seeps were studied using diverse geochemical tools firstly each of the different hydrocarbon types was considered individually with respect to source organofacies level of thermal maturity and degree of biodegradation the results obtained from the source related parameters demonstrate a marine algal source for all investigated samples also lithology determination based on various diasterane tricyclic terpane hopane and homohopane parameters suggests a carbonate source for all samples except for the dadas and iskar seeps clastic thereafter considering the influences caused by thermal and biological alteration processes all heavy oils less mature solid bitumens as well as the less biodegraded seep oils were selected to be correlated using selected additional parameters homohopane distributions reveal that solid bitumens compared to heavy oils and seeps are highly enriched in c31 and depleted in higher homologues possibly due to cracking of high molecular weight homologues to lower ones during and or after solidification processes furthermore the similarities observed for the relative abundances of six series of aromatic hydrocarbons and their alkylated counterparts substantiate strong genetic affinities within the sample set finally compound specific stable carbon isotopes of individual components show that solid bitumens are more enriched in 13c than the heavy oils which is mainly attributed to the preferential removal of light isotopes 12c during solidification our results strongly confirm that turkish solid bitumens are genetically related to the nearby heavy oils thereby providing new information on the petroleum system in this part of the southeast anatolia

was there a wind driven tethys circumglobal current in the late cretaceous abstract the problem of the existence of a tethys circumglobal current tcc in the late cretaceous continental geometry campanian is addressed within an ocean model which is expected to strongly overestimate the wind driven tcc volume transport a relatively weak tcc is found for the reconstructed campanian paleogeography used as a measure of the strength of the tcc a circumglobal flow index is introduced this index is based on volume fluxes through meridional sections within the equatorial part of the domain the impact of changes in the paleogeography on the tcc is considered by computing steady flows for different shapes of eurasia the results on the extent of eurasia such that a strong tcc appears provide support that no strong wind driven tcc has existed during the campanian

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

the separation of madagascar and africa identification of a sequence of east west trending magnetic anomalies of mesozoic age in the western somali basin helps define the position of madagascar in the gondwana reconstruction the anomalies are symmetric about ancient ridge segments and are flanked to the north and south by the jurassic magnetic quiet zone the motion of madagascar relative to africa was from the north and began in the middle jurassic about the same time as the initial breakup of gondwanaland sea floor spreading ceased when madagascar assumed its present position in the early cretaceous

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

eustatic control on alluvial sequence stratigraphy a possible example from the cretaceous tertiary transition of the tornillo basin big bend national park west texas u s a paleosol bearing alluvial strata of latest cretaceous and earliest tertiary age are continuously exposed along dawson creek in big bend national park west texas u s a and exhibit a three tier hierarchy of depositional cyclicity meter scale fluvial aggradational cycles facs occur as fining upward successions that are gradation ally overlain by paleosols or are sharply overlain by the coarser grained base of the succeeding fac without an intervening paleosol facs stack into decameter scale fluvial aggradational cycle sets fac sets that also fine upward and from base to top contain either a grad ual upsection increase in soil maturity and soil drainage or a somewhat symmetrical pattern of increasing and decreasing paleosol maturity longer period trends of fac thickness lithologic proportions paleosol maturity and paleosol drainage indicate that two complete and two partial hectometer scale fluvial sequences occur within the study in terval from base to top each sequence is characterized by an asym metric increase and decrease in fac thickness a decrease in the pro portion of sand prone fluvial facies an increase in paleosol maturity and better paleosol drainage whereas facs and fac sets are interpreted to record cyclic epi sodes of channel avulsion and stability and longer term avulsive chan nel drift within the alluvial valley respectively fluvial sequences may coincide with third order sea level changes within the north american western interior seaway as such the cretaceous tertiary k t transition within the tornillo basin may provide an example of me gascale stratigraphic cyclicity that is controlled by eustatic sea level within a fully fluvial succession thickening and thinning successions of facs record a third order period of accelerating transgressive equivalent and decelerating highstand equivalent base level rise and subsequent base level fall falling stage to lowstand equivalent se quence boundaries are placed at the sharp inflection between thinning and thickening facs sand prone facies and immature more poorly drained paleosols are associated with the transgressive equivalent por tion of each sequence and mudrock dominated overbank facies and their associated mature well drained paleosols are associated with the highstand and falling stage equivalent

source rock heterogeneity of the upper jurassic draupne formation north viking graben and its relevance to petroleum generation studies abstract the upper jurassic draupne formation in the north viking graben north sea has been studied to identify lateral and vertical variations in source rock characteristics and their effect on the timing of petroleum generation fourteen source rock samples from the western flank of the graben and five from the eastern flank were analysed using rock eval analysis microscopy open system pyrolysis gas chromatography and kinetic experiments two major organic facies with different petroleum generation characteristics were identified a stratigraphically higher thermally less stable facies corresponding to a type ii kerogen with hi hydrogen index values of 350 mg hc g toc and a stratigraphically lower more stable type ii iii facies with hi values

oil retention and intrasource migration in the organic rich lacustrine chang 7 shale of the upper triassic yanchang formation ordos basin central china the zhang 22 well was drilled in the ordos basin penetrating the chang 7 member of the triassic yanchang formation which cumulatively has more than 80 m 260 ft of black organic rich shale of oil window maturity using 76 samples collected every 1 m 3 ft from the well the effects of stratigraphic fractionation and petroleum expulsion within five intervals of the chang 7 shale were qualitatively and quantitatively documented the organic rich intervals 1 2 and 5 having an average total organic carbon toc of 6 79 wt and pyrolyzable hydrocarbon potential of 9 40 mg g rock i e the amount of hydrocarbons generated by pyrolysis between 300 c and 650 c s2 are defined as generative units in the chang 7 shale system compared to the in source reservoirs or sweet spots i e the third and fourth intervals which contain a lower average toc of 4 19 wt and an average s2 value of 7 17 mg g rock but the highest amount of free oil average total oil of 7 35 mg g rock geochemical and molecular compositions display distinctive differences between samples from these source and reservoir groupings for example bitumens from the generative units proportionally possess lower saturated hydrocarbons 56 66 than those from the in source reservoirs up to 81 the proportions of aromatic and polar compounds in the generative units are accordingly higher than in their counterpart the individual molecular weight distribution of sample extracts displays more light end moieties being enriched in the generative units by applying the compositional mass balance calculation the overall and compound specific expulsion efficiencies in the in source reservoirs are abnormally negative compared to the positive values in the generative intervals this finding in conjunction with the effects of the preferential retention of aliphatic hydrocarbons and the differential expulsion of light molecular weight compounds in the in source reservoirs indicates a short distance intrasource migration of generated petroleum into the sweet spot intervals intervals 3 and 4 from the overlying units intervals 1 and 2 and the underlying interval 5 furthermore when quantifying the total amount of retained petroleum in the shale system an amended assessment has been introduced to overcome the systematic misestimations if only unextracted values for the amount of thermally extractable hydrocarbons volatilized at 300 c mg hc g rock were considered thus the oil crossover effect temperature at which the rate of s2 generation is at maximum shift phenomenon and the hydrogen index being shifted to higher values after extraction all account for identifying intervals 3 and 4 as the in source reservoirs in this study we have not only identified a set of promising in source targets for shale oil exploration and production but we also presented the chemical and molecular composition for these shale oils we have additionally speculated for the intrasource migration model and further discussed the different expulsion efficiencies in the shale system upon the compositional mass balance calculation as well as the stratigraphic fractionation on differentiating the chemical compositions during migration the improved oil quality by fractionation the extra storage potential derived from microfossil quartz the weak adsorptive affinity of oil to organic matter and the good shale susceptibility to hydraulic fracturing all give a promising prospective for exploring and producing shale oil from the chang 7 shale system in the ordos basin

integration of channel and floodplain suites ii vertical relations of alluvial paleosols abstract extrachannel sediments of the lower eocene willwood formation which were subdivided into different pedofacies or developmental stages exhibit two well developed orders of pedofacies sequences over which a grosser scale cyclicity is superposed simple sequences with thicknesses measured in meters are comprised of one or more soil profiles that are bounded above and below by pedogenically unmodified crevasse splay deposits on a larger scale compound pedofacies sequences are tens of meters thick and consist of several simple sequences sandwiched between channel sandstones between these sandbodies pedogenic maturity of the multistorey paleosols progressively increases and then decreases upwards in response to episodic avulsion formation of both compound and simple pedofacies seq ences was largely controlled by local patterns of deposition and erosion that produced vertical variability in both rate of sediment accumulation and parent material because paleosol maturity also reflects the effects of extrabasinal factors a pedofacies megasequence which is hundreds of meters thick developed in response to changes in tectonic activity through willwood time comparison between willwood deposits in the northern and central parts of the bighorn basin also reveals that areally differing sediment accumulation rates and thereby basin subsidence rates can be interpreted from large scale pedofacies sequences consequently paleosols are useful in determining changes in relative rates of sediment accumulation that are controlled by both intrabasinal and extrabasinal factors

back to basics of sequence stratigraphy early miocene and mid cretaceous examples from the new jersey paleoshelf abstract many sequence stratigraphic approaches have used relative sea level curves that are dependent on models or preconceived notions to recognize depositional sequences key stratal surfaces and systems tracts leading to contradictory interpretations here we urge following basic sequence stratigraphic principles independent of sea level curves using seismic terminations facies successions and stacking patterns from well logs and sections and chronostratigraphic data to recognize sequence boundaries other stratal surfaces parasequences and systems tracts we provide examples from the new jersey siliciclastic paleoshelf from the 1 early miocene using academic based chronostratigraphic seismic core downhole and core log data and 2 mid cretaceous using commercial well log seismic and biostratigraphic data we use classic criteria to identify sequence boundaries on seismic profiles by reflection terminations onlap downlap erosional truncation and toplap in cores by surfaces of erosion associated with hiatuses detected using biostratigraphy and sr isotope stratigraphy and changes in stacking patterns and in logs by changes in stacking patterns maximum flooding surfaces mfss are major seismic downlap surfaces associated with changes from retrogradational to progradational parasequence stacking patterns systems tracts are identified by their bounding surfaces and fining generally deepening and coarsening generally shallowing upward trends in cores and well log stacking patterns our miocene examples of sequences m5 4 17 7 16 1 ma and m5 8 20 1 19 2 ma illustrate how basic sequence stratigraphic techniques reveal higher order sequences within myr scale composite sequences our mid cretaceous examples from the new jersey shelf provide a paleoshelf transect spanning the great stone dome to the outer continental shelf to identify parasequences sequences and systems tracts this sequence stratigraphic framework provides insights into myr scale coeval depositional environments across the paleoshelf and reservoir continuity and highlights the application of basic sequence stratigraphic criteria to reservoir scale evaluation not only for oil and gas resources but also for carbon storage

geochemical evolution of organic rich shales with increasing maturity a stxm and tem study of the posidonia shale lower toarcian northern germany hydrocarbon generation and retention processes occurring within gas shales as a response to increases in thermal maturation are still poorly constrained while efforts have been directed at unravelling the resource potential composition and textures of these economically important unconventional systems their spatial variability in chemistry and structure is still poorly documented at the sub micrometer scale here we have characterized samples of the lower toarcian posidonia shale samples from northern germany at varying stages of thermal maturation using a combination of compositional organic geochemistry and spectromicroscopy techniques including synchrotron based scanning transmission x ray microscopy stxm we document geochemical and mineralogical heterogeneities down to the nanometer scale within the investigated samples as a function of their level of thermal maturity in particular authigenic albite crystals containing nanometric halite inclusions have been documented within the investigated mature and overmature samples the presence of such tracers of palaeobrine carbonate interactions supports a maturation scenario for the lower toarcian posidonia shale intimately related to ascending brine fluids rather than a maturation scenario solely resulting from high heat flows in addition various types of asphaltene and nso rich bitumen have been detected within the same samples very likely genetically derived from thermally degraded organic precursors furthermore the formation of nanoporous pyrobitumen has been inferred for samples of gas window maturity likely resulting from the formation of gaseous hydrocarbons by providing in situ insights into the fate of bitumen and pyrobitumen as a response to the thermal evolution of the macromolecular structure of kerogen the results reported here constitute an important step towards better constraining hydrocarbon generation processes during natural shale gas maturation

the age of the weddell basin the deep oceanic basin occupied by the weddell sea separates the east antarctic craton from the antarctic peninsula a largely post palaeozoic orogenic belt an understanding of the tectonic evolution of the basin would resolve most of the remaining problems of gondwanaland reconstruction which revolve around the relative positions of these two fragments and south america norton and sclater1 conclude that indian ocean marine geophysical data essentially support the smith and hallam fit2 but the unacceptable overlap ofundoubtedly old continental crust3 5 on the antarctic peninsula and falkland plateau implies relative motion between the peninsula and east antarctica such motion is not required by the reconstruction of barron and others7 8 which however can be criticized on other grounds9 10 the marine geophysical observations within the intervening ocean basins have proved useful in formulating plate tectonic reconstructions fracture zone trends seafloor spreading type magnetic anomalies crustal heat flux and crustal depth all provide clues to the timing and direction of the continental motions the acquisition of geophysical data from the weddell sea region has been slow11 13 however the combined interpretation of the two largest data sets extant12 13 now being undertaken seems likely to provide a more tightly constrained gondwanaland solution as a first step we report here an estimated age for the weddell sea floor in the area bounded by 60 and 73 s 5 and 35 w shown in fig 1

the sequence stratigraphy of fluvial depositional systems the role of floodplain sediment storage abstract the currently used model for alluvial sequence stratigraphy has been criticised miall 1991 and an alternative model is offered here in this model alluviation mainly takes place during transgressive and not highstand phases when accommodation space allows sediment storage the high capacity for some river systems to store floodplain sediments is a critical consideration the effects of climatic and intrinsic geomorphic changes during fluvial deposition are likely to greatly complicate simple base level controlled sequence models and recognising higher order fourth and fifth order cycles will be particularly difficult

long term and short term global cenozoic sea level estimates backstripping analysis of three continuously cored well dated boreholes from the new jersey coastal plain ocean drilling program odp leg 150x indicates a long term 10 8 n10 7 yr eustatic fall of 100 m since 55 ma early eocene and suggests short term 0 5n3 m y eustatic falls of less than 70 m eustatic estimates are calculated from residuals between the decompacted unloaded and paleodepth corrected records and tectonic subsidence assuming a cooling lithospheric plate because the residuals are similar among the three sites we interpret them as an approximation of the eustatic signal

a pedotype approach to latest cretaceous and earliest tertiary paleosols in eastern montana a pedotype approach to the study of paleosols emphasizes individual profiles it is an alternative approach to the study of geosols which are laterally extensive suites of paleosols or pedofacies which are pedogenically distinctive sedimentary facies this is the first pedotype study of paleosols across the cretaceous tertiary boundary in eastern montana pedotypes allow assessment of sedimentation and fossilization the sequence of paleosols across the cretaceous tertiary boundary at bug creek is one of high temporal resolution because most available geological time can be accounted for by differing degree of development inferred for each pedotype paleosols at bug creek include pedotypes that preserve plant fossils well but were unfavorable for preservation of fossil vertebrates pedotypes also allow reassessment of ecosystem change despite indications of catastrophe at the cretaceous tertiary boundary the array of paleocene and cretaceous pedotypes are not strikingly different the upper cretaceous hell creek formation includes pedotypes interpreted as gleyed alfisols inceptisols and entisols probably formed under seasonally water logged forest and mean annual rainfall of the order of 900 1200 mm most paleosols of the lower paleocene tullock formation were histosols but some can be interpreted as gleyed inceptisols and entisols probably formed under bald cypress swamps in a humid climate with 1200 mm mean annual rainfall broadly comparable pedotypes were present before and after the cretaceous tertiary boundary although paleocene flood plain forest lived in paleosols chemically a little more oligotrophic than cretaceous paleosols this modest difference supports the idea that change to coaly facies in the earliest paleocene was a local shift in sedimentary environment such local changes do not begin to account for profound disruption in specific composition of plant and animal communities at the cretaceous tertiary boundary in eastern montana

early tertiary rupture of the pacific plate 1700 km of dextral offset along the emperor trough line islands lineament abstract between 67 and 40 ma ago a northwest southeast trending fracture system over 8000 km long split the pacific plate and accumulated at least 1700 km of dextral offset between the east and west portions this system here named the emperor fracture zone efz system consisted of several segments one along the present trace of the emperor trough and another along the line islands joined by short spreading ridges the efz terminated at its northern end against the kula pacific ridge and at its southern end in a ridge transform system called the emperor spreading system which extended to the west north of australia the finite angular velocity vector describing the relative motion between the east and west pacific plates is 0 6 ma about a pole at 36 n 70 w this vector added to the known early tertiary motion of the pacific plate with respect to the global hotspot reference frame accounts in large part for the nnw trend of the emperor seamount chain relative to the wnw hawaiian trend without violation of the integrity of the antarctic plate the meiji emperor and emperor hawaiian bends date respectively the initiation 67 ma ago and cessation 40 ma ago of seafloor spreading on the emperor spreading system the postulated early tertiary relative motion along the efz between the east and west pacific plates explains 1 the present misalignment of the two sets of magnetic bights of the pacific 2 the abrupt truncation of eastern pacific bathymetric lineaments against the emperor trough and line islands 3 the contrast in paleolatitude between the eastern and western pacific as indicated by paleomagnetic and sedimentologic studies and 4 the anomalous gravity signature of the central hawaiian ridge that indicates that the ridge loaded thin hot lithosphere

geochemical effects of asphaltene separation procedures changes in sterane terpane and methylalkane distributions in maltenes and asphaltene co precipitates asphaltene precipitation either natural or artificial may be an important cause of observed compositional differences in oils of identical source and maturity we studied variations in both the bulk and molecular compositions of maltenes and asphaltene co precipitates prepared from six different oils using different procedures the first procedure used a single treatment with n pentane iptc to separate asphaltenes from maltenes the second procedure applied four sequential n pentane extractions of the iptc asphaltenes four times 4ptc analyses of resulting fractions included thin layer chromatography tlc gas chromatography gc and gas chromatography mass spectrometry gc ms these asphaltene separation processes resulted in changes in geochemical parameters previously considered to be influenced solely by source or thermal maturity maltene geochemical parameters not significantly affected by multiple n pentane extractions of the n pentane precipitated asphaltenes were the c 15 c 35 n paraffin distributions except for a small increase in higher n alkanes hopane and homohopane distributions tm ts ratios and c 27 c 28 c 29 sterane distributions maltene geochemical parameters which were affected by multiple n pentane washes of the n pentane precipitated asphaltenes were increases in the c 21 and c 22 sterane pregnane to c 27 c 28 c 29 and c 30 sterane and c 20 to c 24 tricyclic terpane to c 29 to c 35 hopane ratios the n pentane precipitated asphaltene co precipitates showed an increasing ratio of methylalkanes to n alkanes in the range from c 25 to c 36 following multiple extractions with n pentane these results suggest mechanisms of molecular interactions between maltenes and asphaltenes

thermal structure of saturn from voyager infrared measurements implications for atmospheric dynamics abstract saturn atmospheric temperatures at the 150 mbar level retrieved from voyager iris measurements indicate the presence of small scale meridional gradients which are approximately symmetric with respect to the equator but are superposed on a large scale hemispheric thermal asymmetry under the assumption that the retrieved values at this atmospheric level represent kinetic temperatures on a constant pressure surface it is suggested that the small scale structure is produced by a meriodional circulation associated with the dissipative decay of the zonal winds with height while the hemispheric asymmetry represents a thermal response to the seasonally varying insolation the small scale gradients are correlated with zonal winds derived from voyager images at mid and high latitudes through the thermal wind relation the calculated thermal wind shears suggest a decay with height of the jet system toward a state of uniform eatward flow the existence of the approximately symmetric zonal winds and associated temperature gradients in the presence of a large scale seasonal thermal response suggests that the jet system is driven at depths substantially below the levels where seasonally modulated insolation is important p 0 5 bar

a revised identification of the oldest sea floor spreading anomalies between australia and antarctica we propose that magnetic anomalies south of australia and along the conjugate margin of antarctica that were originally identified as anomalies 19 to 22 may be anomalies 20 to 34 the original anomaly identification has two troublesome aspects 1 it does not account for an extra anomaly between anomalies 20 and 21 and 2 it provides no explanation for the rough topography comprising the diamantina zone with our revised identification there is no extra anomaly and the diamantina zone is attributed to a period of very slow spreading 4 5mm yr half rate between 90 and 43 m y the ages bounding the interval of slow spreading 90 and 43 m y correspond to times of global plate reorganizations our revised identification opens up the possibility that part of the magnetic quiet zone south of australia formed during the cretaceous long normal polarity interval breakup of australia and antarctica probably occurred sometime between 110 and 90 m y b p the breakup unconformity identified by falvey in the otway basin may correspond to a eustastic sea level change

fluvial responses to climate and sea level change a review and look forward summary fluvial landforms and deposits provide one of the most readily studied quaternary continental records and alluvial strata represent an important component in most ancient continental interior and continental margin successions moreover studies of the long term dynamics of fluvial systems and their responses to external or allogenic controls can play important roles in research concerning both global change and sequence stratigraphy as well as in studies of the dynamic interactions between tectonic activity and surface processes these themes were energized in the final decades of the twentieth century and may become increasingly important in the first decades of this millennium this review paper provides a historical perspective on the development of ideas in the fields of geomorphology quaternary geology vs sedimentary geology and then summarizes key processes that operate to produce alluvial stratigraphic records over time scales of 103 106 years of particular interest are changes in discharge regimes sediment supply and sediment storage en route from source terrains to sedimentary basins as well as changes in sea level and the concept of accommodation late quaternary stratigraphic records from the loire france mississippi usa colorado texas usa and rhine meuse the netherlands rivers are used to illustrate the influences of climate change on continental interior rivers as well as the influence of interacting climate and sea level change on continental margin systems the paper concludes with a look forward to a bright future for studies of fluvial response to climate and sea level change at present empirical field based research on fluvial response to climate and sea level change lags behind a the global change community s understanding of the magnitude and frequency of climate and sea level change b the sequence stratigraphic community s desire to interpret climate and especially sea level change as forcing mechanisms and c the modelling community s ability to generate numerical and physical models of surface processes and their stratigraphic results a major challenge for the future is to catch up which will require the development of more detailed and sophisticated quaternary stratigraphic sedimentological and geochronological frameworks in a variety of continental interior and continental margin settings there is a particular need for studies that seek to document fluvial responses to allogenic forcing over both shorter 102 103 years and longer 104 106 years time scales than has commonly been the case to date as well as in larger river systems from source to sink studies of quaternary systems in depositional basin settings are especially critical because they can provide realistic analogues for interpretation of the pre quaternary rock record

a reproducible and linear method for separating asphaltenes from crude oil abstract petroleum asphaltenes exhibit strong structural similarities to their parent kerogen thus they can be used to help determine the source rock characteristics of active kitchen areas and to reconstruct the filling histories of reservoirs the analysis of asphaltenes from compartmentalised reservoirs with complex charging and alteration histories presents a particularly difficult challenge because the in situ compositional variations are sometimes subtle it is therefore of paramount importance that asphaltene separation methods be utilised which are highly reproducible and linear thereby minimising experimental uncertainty and providing high resolution interpretative capability the asphaltene separation method described here is built on many that have been proposed before different parameters for asphaltene separation were investigated which influence the asphaltene amount and properties with the main focus on reproducibility and linearity gravimetric and thermal analysis techniques were used to evaluate yield and quality the developed asphaltene separation method described in detail has four sequential steps 1 dissolution of the oil in dichloromethane 1 vol methanol 2 addition of an excess of n hexane 3 settling time and 4 filtration purging and weighing this sequence of steps is repeated three times results concerning the reproducibility depending on solvent type solvent amount and aging time as well as the linearity depending on sample amount are presented

storm features of siliciclastic shelf sedimentation in the mid cretaceous epeiric seaway of northern australia abstract late aptian to early cenomanian strata were deposited in a large epeiric seaway which covered much of the northern australian landmass during mid cretaceous time the seaway stretched from the carpentaria basin in the north to the eromanga basin in the south during this period siliciclastic sediments accumulated on a gently sloping epeiric shelf which formed the western margin of the carpentaria basin the shelf maintained a relatively similar configuration throughout the mid cretaceous with water depths rarely exceeding 50 m and the seafloor was apparently within the influence of storm waves over much of the area the shelf was storm and wave dominated and most early formed or fair weather sedimentary structures were destroyed or extensively modified during episodic storms storm features include hummocky cross stratification shelly lags erosional conglomeratic lags gutter casts lenticular micro hummocky sand beds megaripples characteristic low diversity and opportunistic ichnofacies various styles of wave ripple lamination and poorly preserved event beds most storm influenced units are preserved as coarsening and shallowing upwards facies successions which aggraded during high relative sea level and prograded during falling relative sea level some of these successions were subsequently eroded during further cyclic fluctuations of relative sea level

neptune s stratospheric winds from three central flash occultations abstract we present observations of three neptune central flash events the 20 august 1985 occultation of n39 from the european southern observatory eso the 12 september 1988 occultation of n51 from pic du midi and the 8 july 1989 occultation of n55 from eso from simultaneous fits to the three central flash lightcurves we determine the shape of neptune s limb and show that winds near the 0 38 mbar level have decayed to about 0 6 0 2 times their strength at 100 mbar assuming that the latitude dependence of the stratospheric winds follows the zonal wind profile of l a sromovskyet al 1993 icarus105 110 141 from the measured decay of winds with height we find that the average vertical shear in the zonal wind between 100 and 0 38 mbar is very close to the voyager iris results for the 30 to 120 mbar region b j conrathet al 1989 science246 1454 1459 at the latitudes to which the central flashes are most sensitive we also determine the shape of the limb at the 0 7 bar level from the half light points of the atmospheric immersion and emersion light curves of five stellar occultations by neptune the winds in this pressure regime have decayed to 0 17 times their strength at the 100 mbar level and the vertical shear in the zonal wind as determined from the thermal wind equation and voyager iris measurements extends essentially unchanged all the way up to the microbar level of the stratosphere alternatively a simple oblate model fit to the planetary limb gives an oblateness of 0 0180 0 0010 and an equatorial radius ofre 25262 7 3 5 km the corresponding rotation period is 16 59 0 92 h quite similar to that of neptune s deep interior 16 11 h this near corotation suggests that there is some coupling between neptune s interior and the upper stratosphere even though the intervening atmosphere between the cloud deck and the stratosphere has strong retrograde flow

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

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

geocarbsulf a combined model for phanerozoic atmospheric o2 and co2 abstract a model for the combined long term cycles of carbon and sulfur has been constructed which combines all the factors modifying weathering and degassing of the geocarb iii model berner r a kothavala z 2001 geocarb iii a revised model of atmospheric co2 over phanerozoic time am j sci 301 182 204 for co2 with rapid recycling and oxygen dependent carbon and sulfur isotope fractionation of an isotope mass balance model for o2 berner r a 2001 modeling atmospheric o2 over phanerozoic time geochim cosmochim acta 65 685 694 new isotopic data for both carbon and sulfur are used and new feedbacks are created by combining the models sensitivity analysis is done by determining 1 the effect on weathering rates of using rapid recycling rapid recycling treats carbon and sulfur weathering in terms of young rapidly weathering rocks and older more slowly weathering rocks 2 the effect on o2 of using different initial starting conditions 3 the effect on o2 of using different data for carbon isotope fractionation during photosynthesis and alternative values of oceanic 13c for the past 200 million years 4 the effect on sulfur isotope fractionation and on o2 of varying the size of o2 feedback during sedimentary pyrite formation 5 the effect on o2 of varying the dependence of organic matter and pyrite weathering on tectonic uplift plus erosion and the degree of exposure of coastal lands by sea level change 6 the effect on co2 of adding the variability of volcanic rock weathering over time berner r a 2006 inclusion of the weathering of volcanic rocks in the geocarbsulf model am j sci 306 in press results show a similar trend of atmospheric co2 over the phanerozoic to the results of geocarb iii but with some differences during the early paleozoic and for variable volcanic rock weathering lower co2 values during the mesozoic atmospheric oxygen shows a major broad late paleozoic peak with a maximum value of about 30 o2 in the permian a secondary less broad peak centered near the silurian devonian boundary variation between 15 and 20 o2 during the cambrian and ordovician a very sharp drop from 30 to 15 o2 at the permo triassic boundary and a more or less continuous rise in o2 from the late triassic to the present

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

late paleocene arctic ocean shallow marine temperatures from mollusc stable isotopes late paleocene high latitude 80 n arctic ocean shallow marine temperatures are estimated from molluscan 18o time series sampling of individual growth increments of two specimens of the bivalve camptochlamys alaskensis provides a high resolution record of shell stable isotope composition the heavy carbon isotopic values of the specimens support a late paleocene age for the youngest marine beds of the prince creek formation exposed near ocean point alaska the oxygen isotopic composition of regional freshwater runoff is estimated from the mean 18o value of two freshwater bivalves collected from approximately coeval fluviatile beds over a 30 34 range of salinity values assumed to represent the tolerance of c alaskensis the mean annual shallow marine temperature recorded by these individuals is between 11 and 22 c these values could represent maximum estimates of the mean annual temperature because of a possible warm month bias imposed on the average 18o value by slowing or cessation of growth in winter months the amplitude of the molluscan 18o time series probably records most of the seasonality in shallow marine temperature the annual temperature range indicated is approximately 6 c suggesting very moderate high latitude marine temperature seasonality during the late paleocene on the basis of analogy with modern chlamys species c alaskensis probably inhabited water depths of 30 50 m the seasonal temperature range derived from 18o is therefore likely to be damped relative to the full range of annual sea surface temperatures high resolution sampling of molluscan shell material across inferred growth bands represents an important proxy record of seasonality of marine and freshwater conditions applicable at any latitude if applied to other regions and time periods the approach used here would contribute substantially to the paleoclimate record of seasonality

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

cretaceous plate tectonic reconstructions abstract plate tectonic reconstructions for each cretaceous stage are produced as base maps for cretaceous paleogeography and for oceanic and continental data both geologic and geophysical data are utilized to determine the relative rotations of cretaceous plates with respect to north america a sea floor spreading history is generated from the relative rotations this history is consistent with data from the deep sea drilling project paleolatitude lines are derived using average paleomagnetic pole positions these reconstructions are significantly more comprehensive than previous global reconstructions although there are still many areas which remain controversial

cadalenes and norcadalenes in organic rich shales of the permian irati formation parana basin brazil tracers for terrestrial input or also indicators of temperature controlled organic inorganic interactions abstract cadalene isocadalene and a series of norcadalenes were identified in black shales of the permian irati formation in the northeastern and central eastern parana basin brazil the origin of their isomers with an isopropyl substituent is potentially related to higher plants and likely reflects the spreading of pteridophytes and gymnosperms after the glaciation of southern gondwana a general increase in the relative abundance of isocadalene 1 6 dimethyl 3 isopropylnaphthalene the isomer co occurs in with increasing thermal maturity at the base of the amaral machado quarry northeastern basin and refers to the acid catalyzed rearrangement of cadalene 1 6 dimethyl 4 isopropylnaphthalene the isomer due to the presence of montmorillonite via an organic inorganic interaction this localized and incipient maturation can be related to diabase sills of the serra geral formation similar maturation due to heating also affected the distribution of the norcadalenes by thermally stabilizing their isomers with an isopropyl substituent in addition to the formation of related compounds with an ethyl substituent based on this a norcadalene ratio is proposed which is the sum of the 1 6 dimethyl 4 ethylnaphthalene and 1 6 dimethyl 3 ethylnaphthalene over the sum of the 1 isopropyl 4 methylnaphthalene and 1 isopropyl 7 methylnaphthalene the results of this ratio and the established cadalene ratio resemble each other whereas samples from the sao mateus do sul quarry central eastern basin were not affected by thermal maturation and are characterized by a uniform distribution of the cadalenes and norcadalenes

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