mineralogical characterization of coal samples relevant to coal bed methane porosity and permeability concerns lower than anticipated gas production rates in coal bed methane cbm operations are sometimes related to formation damage in which reduced permeability results from the interaction of bore and fracturing fluids with coal this study assesses the potential for mineral recipitation to cause formation damage from a permian coal seam in the bowen basin eastern australia using geochemical modelling of coal mineralogy formation fluid and bore fluid composition the mineralogical composition of coal was assessed using petrography x ray iffraction x ray fluoresence and electron beam microanalysis geochemical modelling of ambient groundwater and drilling fluid interactions with coal samples was undertaken using geochemist s work bench gwb this modelling indicates that likely mineral precipitates re precipitates to adversely impact porosity and permeability include a range of clay carbonate and sulphate minerals additionally these interactions may induce alteration of precursor smectites to new species that reduce permeability the resultant smectites also have a high propensity for expansion and dispersion in the presence of inappropriate drilling fluids precipitation expansion and dispersion of these fine grained minerals may potentially lead to large reductions in permeability with profound impacts upon gas flow indications are that reduced permeability can be mitigated by suitable chemical matching of ground waters with drilling fluids

decoupling δ13c response to palaeoflora cycles and climatic variation in coal a case study from the late permian bowen basin queensland australia abstract the late permian coal measures of the bowen basin australia express both environmental and climatic changes that occurred prior to the permian triassic p t boundary in order to decouple the influence of environmental factors salinity ph base level and temperature from depositional and climatic factors atmospheric co2 in organic 13c a high resolution study was performed on 24 coal seams total 24 6 m in the late permian stratigraphy in the northern bowen basin the late permian stratigraphy of the bowen basin records a transition from deltaic and lacustrine conditions within the tinowan formation and black alley shale formation to fluvial deposition in the kaloola and bandanna formations intermittent volcanism is recorded by tuff layers during periods of peat accumulation variations of coal lithotypes were recorded and formed the basis of sampling for petrography and isotope analysis coal samples were etched to expose cellular anatomy and systematically identified to recognise palaeoflora assemblages when observed within seam 13c of the coal varied cyclically 13c enriched depleted enriched as a response to environmental changes expressed in palaeoflora communities the total range of 13c was 26 6 to 21 9 the overall trend of 13c progresses to increasing 13c enrichment corresponding with dull lithotypes rich in inertinite which indicate fluctuations in base level the 13c enrichment peaks at 22 5 within the kaloola member and shifting rapidly toward a depletion maximum 26 6 of 13c in the upper bandanna formation prior to the p t boundary these changes are expressed in palaeoflora communities where ecosystems shifted from dominant glossopteris flora to climax community flora including palaeosmunda cycadales and ginkgo suited to temperate early mesozoic climates the results of this study represent an insight into the effects of environmental variables on 13c uptake of plants the identification of flora within coal gives an insight into palaeowetland evolution and can be partnered with classic petrographical techniques for integrated analysis in coals both the geochemistry and the anatomical aspects of coal represent an important tool for future palaeowetland research

root related rhodochrosite and concretionary siderite formation in oxygen deficient conditions induced by a ground water table rise sedimentological mineralogical stable carbon and oxygen isotope determinations and biomarker analyses were performed on siderite concretions occurring in terrestrial silts to understand their formation and to characterize the sedimentary and diagenetic conditions favouring their growth high 13c values 6 4 on average indicate that siderite precipitated in an anoxic environment where bacterial methanogenesis operated the development of anoxic conditions during shallow burial was induced by a change in sedimentary environment from flood plain to swamp related to a rise of the ground water table large amounts of decaying plant debris led to efficient oxygen consumption within the pore water in the peat oxygen depletion in combination with a decrease in sedimentation rate promoted anoxic diagenetic conditions under the swamp and favoured abundant siderite precipitation this shows how a change in sedimentary conditions can have a profound impact on the early diagenetic environment and carbonate authigenesis the concretions contain numerous rhizoliths they are cemented with calcium rhodochrosite a feature which has not been reported before the rhodochrosite cement has negative 13c values 16 5 on average and precipitated in suboxic conditions due to microbial degradation of roots coupled to manganese reduction the exceptional preservation of the epidermis exodermis and xylem vessels of former root tissues indicates that the rhodochrosite formed shortly after the death of a root in water logged sediments rhodochrosite precipitated during the initial stages of concretionary growth in suboxic microenvironments within roots while siderite cementation occurred simultaneously around them in anoxic conditions these suboxic microenvironments developed because oxygen was transported from the overlying oxygenated soil into sediments saturated with anoxic water via roots acting as permeable conduits this model explains how separate generations of carbonate cements having different mineralogy and isotopic compositions which would conventionally be regarded as cements precipitated sequentially in different diagenetic zones during gradual burial can form simultaneously in shallow burial settings where strong redox gradients exist around vertically oriented permeable root structures

the thermal history of the bowen basin queensland australia vitrinite reflectance and clay mineralogy of late permian coal measures abstract the thermal history of the bowen basin queensland australia has been investigated using vitrinite reflectance data and clay mineralogy vitrinite reflectance data combined with a study of clay mineral reactions indicates that the maximum temperatures which induced organic maturation of the bowen basin coals and extensive clay mineralisation are not related to deep burial metamorphism during the latest middle triassic earliest late triassic as previously believed the results of the present study indicate that the development of a zone of high heat flow in the latest late triassic had a major control on the thermal history of the bowen basin high palaeogeothermal gradients estimated in the northern bowen basin are interpreted to result from convective heat transfer during a hydrothermal event variable heat distributions due to localised fracture enhanced permeable zones acting as hot reservoirs in the deeper part of the basin may have been responsible for some significant local thermal anomalies in the lower coal measures the estimated palaeogeothermal gradients in the southern bowen basin also indicate high heat flow in the lower sections of the stratigraphy sections in the southern bowen basin however are believed to reflect a rock dominated semi closed system with low water rock ratio where rocks are impervious to circulating fluids and thus heat transfer may have occurred by conduction the correlation between vitrinite reflectance and clay mineralogy shows a delay in illitisation reaction relative to organic maturity for many illite smectite i s mixed layer clays in the northern bowen basin this phenomenon can be explained as a result of insufficient time for the completion of mineral reactions and a variable potassium supply in relatively impermeable rocks the relationship between i s expandability and vitrinite reflectance for the bowen basin data compared to basins with known tectonic regimes suggests a thermal history in a rift setting for the bowen basin the effect of thin igneous intrusions on clay mineral reactions is very limited intensive illitisation due to heating of intrusions can only be observed in narrow zones immediately adjacent to intrusive bodies this further demonstrates that mineral reactions are too slow to record the effect of extremely short heating duration in contrast to organic maturity indicators these differences between mineral and organic parameters aid in the identification of local contact metamorphic effects

crayfish burrows from the latest cretaceous lower cantwell formation denali national park alaska their morphology and paleoclimatic significance abstract latest cretaceous strata of the lower cantwell formation denali national park central alaska range contain an abundance of megafloral remains and invertebrate and vertebrate trace fossils though dominated by herbivorous dinosaur footprints the abundance and diversity of fossil bird tracks are unique we present newly discovered crayfish burrows from several areas along a 50 km transect with denali national park most crayfish burrows from the lower cantwell formation are preserved only in cross section and range from approximately 5 10 cm in diameter where preserved in full relief and terminations present burrow depth is generally the cantwell formation fills the cantwell basin a 135 km long and up to 35 km wide east west trending basin bracketed by the hines creek fault to the north and the mckinley fault to the south basin fill comprises up to 4000 m of continental deposits interpreted as braided rivers alluvial fans floodplains swamps and ponds crayfish burrows provide evidence of water table level soil moisture fluctuations as well as insight into mean annual temperatures at the time of deposition of the lower cantwell formation a late cretaceous high latitude paleoecosystem despite a relatively high latitudinal setting 71 n paleolatitude the late cretaceous i e campanian maastrichtian mean annual temperature based on the distribution of similar present day crayfish burrows was more like that of southernmost ontario canada where the northernmost burrowing crayfish are found today the burrow depth suggests 1 no permafrost was present and 2 the phreatic zone was 30 50 cm below the paleo ground surface based on the presence of these crayfish burrows the paleoclimate is interpreted as humid continental koppen scheme with average summer high temperatures between 25 c and 28 c and average winter low temperatures between 6 c and 0 c these estimates compare somewhat favorably with previous clamp estimates of a warm monthly mean temperature of 17 08 1 6 c and a cold monthly mean temperature of 2 31 1 9 c

occurrence of minerals within fractures and matrix of selected bowen and ruhr basin coals abstract late permian age samples of black coal from the coeval bandanna formation and baralaba coal measures of queensland s bowen basin as well as carboniferous coal from germany s ruhr basin were investigated this paper presents scanning electron microscope sem analysis of the mode of occurrence of minerals within these coals and characterisation of the natural fractures present within the samples the coal samples located proximal to orogenic fronts in both basins are structurally complex with multiple generations of mineralisation evident stable isotope analyses of carbonates from selected samples indicate that methanogenesis related co2 reduction has occurred at two of the bowen basin sampling locations ankerite precipitated from a magmatic fluid or basinal brine is associated with significant sulphide mineralisation within brecciated ruhr coal proximal to major fault intersections with anticlines and has been meteorically altered to ferroan calcite and sulphates in coal from immediately below the carboniferous cretaceous unconformity similar alteration has occurred within a bowen basin coal sample close to the present day land surface variation of mineralisation within both the cleats and the coal matrix occurs on a fine scale with crystals of multiple mineral species often being present within micrometres of each other

origin distribution and significance of carbonate cements in the albert formation reservoir sandstones new brunswick canada abstract carbonate cements in the fluvio lacustrine reservoir sandstones of the albert formation mainly occur in three phases pre compaction calcite post compaction calcite and ankerite the precompaction calcite cement 25 to 40 is characterised by bright luminescence high concentrations of fe mn and sr means of 1 56 wt 1 42 wt and 0 25 wt respectively slightly heavy 13c and 18o values mean 1 79 pdb mean 14 99 pdb respectively and its selective occurrence in lacustrine sandstones suggestive of cementation at shallow depths from lacustrine connate water dull luminescence variable concentrations of fe mn and sr variable but slightly heavy 13c and 18o values mean of 2 97 pdb and 11 05 pdb respectively of the post compaction calcite as well as its occurrence in alluvial fan sandstones exhibiting high pressure solution of detrital grains suggest cementation from pore waters modified by water rock interactions we suggest that the ankerite cement was formed from upwardly migrating formation water based on the following evidence i ankerite cement filling the secondary pores created in the deep subsurface ii an absence of unconformity during ankerite cementation precluding involvement of meteoric water iii ankerite cementation in brecciated veins synchronous with ankerite precipitation in host sandstones iv occurrences of significant volumes of ankerite 20 to 30 in the shales indicating that the fe and mg ions expelled during smectite to illite transformation reactions were consumed within the shales and v the heavy 13c and 18o isotope values of the ankerite cements means of 2 2090 pdb and 11 05 pdb respectively

insight on seismic hazard studies for egypt abstract the seismic hazard studies for egypt have been initiated a long time ago aiming to predict the ground motion parameters at different geographical scales their review process had been routinely performed due to the increase of available instrumental observations rather than from methodological advances for the comprehensive understanding of the development of seismic hazard assessment sha studies in egypt we properly collect and test the existing sha maps computed at different geographic scales against the available observations data quality physical assumptions and adopted methodology most of these sha studies are probabilistic and the mapped ground motion acceleration values have been often largely exceeded by the observed values due to earthquakes occurred after their publication for each study we discuss and evaluate the input data methodology and the results obtained in order to understand the reasons behind the bad performance of the available seismic hazard maps and to avoid such shortcomings in future seismic hazard assessment finally we formulate suggestions that could be considered before new seismic hazard maps are released and then adopted for the real benefit of society

formation of complex fibrous calcite veins in upper triassic strata of wrangellia terrain british columbia canada abstract fibrous calcite veins are ubiquitous throughout the thinly bedded organic rich upper triassic marine mdrocks of the queen charlotte islands and their lateral equivalents on vancouver island these veins show variable and complex morphologies and can be grouped into several types a simple b anastomosing or composite c boxwork and 4 polygonal network oriented normal to bedding field petrographic and geochemical evidence suggest that vein opening resulting from hydraulic fracturing due to elevated pore fluid pressures was an early phenomenon and occurred prior to significant compaction of the host sediments calcite fibers in the veins are up to 30 mm long and commonly oriented perpendicular to the wall but locally display conical structures fibrous calcites with the exception of those in boxwork veins are generally non ferroan and dull to very weakly orange luminescent the boxwork calcites are ferroan zoned and show dull luminescence with some bright rims 18 o values range from 8 2 to 21 6 pdb and 13 c values range from 2 0 to 4 4 pdb although some variations are present among the different morphological types of calcite veins oxygen and carbon isotopic values display important variations when compared geographically the most depleted oxygen and carbon isotopic values are those of boxwork calcite and they are associated with areas where the effects of early mesozoic plutonism were most severe precipitation of boxwork fibrous calcites is interpreted to have been related to hydrothermal discharge into unconsolidated host sediment rather than to later burial although the hydrothermal influence on the formation of vein calcite is related to geological events specific to the wrangellia terrain this study provides an alternative mechanism for the generation of fibrous calcite veins and demonstrates the local importance of hydrothermal input in the evolution of pore water chemistry

permian evolution of sandstone composition in a complex back arc extensional to foreland basin the bowen basin eastern australia abstract the bowen basin is a permo triassic back arc extensional to foreland basin that developed landward of an intermittently active continental volcanic arc associated with the eastern australian convergent plate margin the basin has a complex polyphase tectonic history that began with limited back arc crustal extension daring the early permian this created a series of north trending grabens and half grabens which in the west accommodated quartz rich sediment derived locally from surrounding uplifted continental basement in the east coeval calc alkaline volcanolithic rich and volcaniclastic sediment was derived from the active volcanic arc this early extensional episode was followed by a phase of passive thermal subsidence accompanied by episodic compression during the late early permian to early late permian with little contemporaneous volcanism in the west quartzose sediment was shed from stable polymictic continental basement immediately to the west and south of the basin whereas volcanolithic rich sediment that entered the eastern side of the basin during this time was presumably derived from the inactive and possibly partly submerged volcanic arc during the late late permian flexural loading and increased compression occurred along the eastern margin of the bowen basin and renewed volcanism took place in the arc system to the east reactivation of this arc led to westward and southward spread of volcanolithic rich sediment over the entire basin accordingly areas in the west that were earlier receiving quartzose craton derived sediment from the west and south were overwhelmed by volcanolithic rich arc derived sediment from the east and north this transition from quartz rich craton derived sediments to volcanolithic rich arc derived sediments is consistent with the interpreted back arc extensional to foreland basin origin for the bowen basin

distribution chemistry isotopic composition and origin of diagenetic carbonates magnus sandstone north sea abstract diagenetic ferroan carbonates grew in the upper jurassic reservoir sandstones of the magnus oilfield in porewaters which differed in composition across the field these porewaters remained compositionally different and stratified for at least 35 m y variations in carbonate chemistry across the field are attributable to these porewater variations which resulted from displacement of marine depositional water from the crest of the field by meteoric water during late cimmerian subaerial exposure original depositional facies and detrital mineralogy strongly influenced diagenetic carbonate distribution rare diagenetic calcite occurs as discrete rhombic crystals diagenetically late magnesian siderites have developed throughout the reservoir sandstone and are commonly intimately associated with altered detrital biotite grains poikilotopic ankerite cement postdates calcite and siderite and occurs only adjacent to mudstones and in thin sandstones within mudstones three compositional growth zones in siderite crystals are observed across the field from crest to flank in all three wells studied a similar trend of compositional evolution through time is observed in both two and three zoned rhombs first formed siderite is relatively magnesian intermediate zones are more ferroan and outer zones are at least as magnesian as the first stage these individual grain variations overprint a fieldwide variation where siderite is more ferroan in the crestal samples up to 87 mol fe mn and more magnesian downdip up to 58 mol mg this reflects the greater influence of relatively fe rich meteoric derived water in the crest and the greater influence of marine derived mg rich porewater downdip ankerite shows a similar variation in fe and mg abunda ces across the field crest and flank maximum 25 and 17 mol fe mn respectively 27 and 43 tool mg and developed due to release of mg fe ca and hco3 ions from mudstones into adjacent sandstones following dissolution of detrital minerals and organic decarboxylation reactions both siderite and ankerite have lower 18o at the crest of the oilfield than downdip respectively siderite 16 0 and 17 6 smow ankerite 17 7 and 21 4 these differences in 18o reflect the retention during burial diagenesis of a larger component of meteoric water in the crest of the field below the unconformity whereas downdip porefluid contained a larger marine derived component strong organic influence on 13c 8 0 to 14 6 pdb for magnesian siderite 7 7 to 13 6 for ankerite closed system 34s values up to 15 7 for late cubic pyrite and stratified 18o from crest to flank of the field argue against large scale porewater movements diagenetic porewater stratification is strongly supported by the parallel but distinct geochemical fingerprints of siderite and ankerite cements from the crest to the flank of the field

palaeoecology of late cretaceous polar vegetation preserved in the hansen point volcanics nw ellesmere island canada abstract mesozoic polar forests represent an extinct biome subject to a polar light regime and elevated atmospheric co2 levels in this paper new cretaceous fossil plant assemblages are reported from nw ellesmere island canada at a paleolatitude of 75 n these occur in a campanian maastrichtian aged interval of the hansen point volcanics a unit interpreted as a coastal plain peat mire complex within an active volcanic setting studies of palynomorphs sterile and fertile foliage and wood indicate that mire environments were dominated by amber producing taxodiaceous conifers with other conifers ginkgos cycads angiosperms ferns lycopsids and bryophytes occurring in subordinate numbers leaf physiognomic studies imply that most vegetation was deciduous occurrence of traumatic rings in the woods together with a high year to year variability in ring width indicates disturbed growing conditions possibly linked to a combination of frosts volcanic eruptions and flooding abundant charcoal remains indicate that an additional important disturbance process was wildfire results of this study compare closely with those from coeval circum arctic fossil sites and augment our knowledge of the community scale ecology of the cretaceous polar biome

fluid flow in sedimentary basins abstract the pore waters in sedimentary basins are ultimately derived from sea water meteoric water mineral bound water or from the underlying basement geochemically these waters initially have different signatures however the pore water compositions are easily altered by reactions with minerals or by mixing with other fluids meteoric water is driven downwards into sedimentary basins by the gravitational potential which approximately corresponds to the elevation of the ground water table above the sea or lake level it is difficult to model such flow however because the permeability on a large scale is almost impossible to represent realistically the continuity of confined sandstone and limestone aquifers plays an important role in determining the flux of meteoric water received by rocks in different parts of the basin but this is again difficult to predict pore water flow driven by compaction typically has velocities several orders of magnitude lower than what is commonly found in meteoric water flow regimes the average rate of upwards flow is lower than the rate of subsidence and the difference is the rate of incorporation of sea water in the topmost layer at the sea floor the salinity of formation water provides important constraints on fluid flow in sedimentary basins in the north sea basin and the gulf coast basin these types of data indicate that vertical mixing by compaction driven flow and convection is limited compaction driven flow obeys darcy s law but there are complex interdependencies between pressure permeability and compaction given the low compressibility of water the flow which can result from pressure release alone is very limited except on a local scale along permeable faults and fractures the main flow of pore water during burial is driven by compaction which is a slow process even when overpressure is released abruptly with a resulting increase in the net effective stress in the case of high permeability faults the flow into the fault from low permeability sedimentary rocks at depth may be rate limiting the displacement of pore water in adjacent sediments near the top of the faults may also slow down fluid flow on fractures that do not reach the sea floor modelling of fluid flow in sedimentary basins should be based on permeability distributions which are mostly determined by primary facies diagenesis and the tectonic history of the basin extensional tectonics produce a predominantly vertical fracture network which may serve as conduits for pore water flowing deep into the crust upward flow of hot fluids in basement fractures must have a high velocity in order to produce large thermal anomalies concentrations of dissolved components precipitate at the surface and form deposits of quartz and ore minerals if basement fractures are overlain by a thick sequence of soft sediments the rate of flow on the fractures will be reduced because of the low permeability in the sedimentary cover and conductive heat transport will dominate flow of water at high enough velocities to bring hot water to the surface and produce hot springs is most likely to occur in fractured basements rocks or well cemented sedimentary rocks concentrated precipitation of dissolved components will occur near the surface where the rate of cooling is highest also sediment hosted ores precipitated from flow of hot water on fractures are therefore likely to form before accumulation of thick overlying sedimentary sequences

the late cretaceous environment of the arctic a quantitative reassessment based on plant fossils abstract late cretaceous megafossil floras from the palaeo arctic of northeastern russia and northern alaska are reviewed in respect of their age composition structure and floral dynamics palaeofloral correlations and comparisons are made between the two regions nine angiosperm rich predominantly cenomanian to coniacian floras from the palaeo arctic are re evaluated using climate leaf analysis multivariate program clamp calibrated using a global gridded 0 5 0 5 climate data set derived from that used in climate modelling additional floras from lower palaeolatitudes were used to derive latitudinal temperature gradients seven from n america five from around 30 n palaeolatitude in europe and one from kazakhstan the arctic climatic determinations similar to previous estimates support the existence of a northern pacific ocean cold gyre and a warm arctic ocean at palaeolatitudes greater than 80 n floras are insufficiently diverse in woody dicot taxa to use clamp but using clamp derived latitudinal temperature gradients arctic ocean coastal environments at 70 ma and 82 n and which supported a diverse dinosaur magafauna are predicted to have experienced a mean annual temperature of 6 3 2 2 c a warm month mean of 14 5 3 1 c and a cold month mean no colder than 2 0 3 9 c all uncertainties are 2 the new estimates are in good agreement with a wide range of non palaeobotanical climate proxies and render as an outlier warmer temperature estimates for the arctic ocean derived from the tex 86 proxy modelling however shows that land to ocean temperature gradients could have been steep the clamp estimates also suggest high values for humidity and precipitation consistent with sedimentological indicators and coupled with warm temperatures support the existence of a persistent polar cloud cap that helped maintain high terrestrial air temperatures throughout prolonged periods up to 5 months of winter darkness

paleofloristic and paleoenvironmental information from a late cretaceous maastrichtian flora of the lower cantwell formation near sable mountain denali national park alaska abstract the lower cantwell formation in denali national park alaska is a late cretaceous high latitude fluvial succession that contains dinosaur and bird footprints diverse invertebrate traces and plant fossils new fossil discoveries and stratigraphic descriptions in the sable mountain area allow for refined paleoenvironmental reconstructions and age interpretations the formation consists of well indurated conglomerate sandstone siltstone and shale interpreted as gravelly and sandy channel levee crevasse splay sheetflood lacustrine and floodplain sediments with interspersed debris flows the overall depositional environment is interpreted as a braided river floodplain that interfingered with distal alluvial fan sedimentation plant fossils include leaves branches cones and rare seeds of taxodiaceous and other conifer taxa fern fronds rhizomes and stem segments of equisetites linear and broad lanceolate monocot leaf fragments cf kenella and impressions of diverse angiosperm broad leaf morphotypes likely belonging to menispermoid platanoid and several late cretaceous hamamelid groups a sparse palynoflora extracted from the finer grained facies yielded the pollen taxa taxodiaceaepollenites aquilapollenites and alnipollenites monosulcate cycadophyte or ginkgophyte pollen grains bisaccate and monosaccate conifer pollen grains and a variety of trilete fern and psilate horsetail spores the middle to late maastrichtian pollen taxon aquilapollenites conatus provides a maximum age for the sable mountain deposits floral assemblages occur within distinct lithofacies deposited in a variety of depositional settings in the ancient floodplain angiosperm leaf fossils are dominant in channel and levee facies and were part of a mixed forest assemblage growing in floodplain and lake margin environments a variety of different types of conifers indicated by saccate pollen types and rare long thin leaf fragments probably inhabited distal floodplain realms and uplands frequent and abrupt changes in lithology and floral assemblages imply transitory habitats in a rapidly aggrading depositional setting a climate leaf analysis multivariate program clamp applied to a composite leaf collection yielded a mean annual temperature of 7 42 1 2 c a warmest monthly mean of 17 1 1 6 c and a coldest monthly mean of 2 3 1 9 c growing season precipitation is estimated at 229 4 334 5 mm over 4 8 0 7 months results are suggestive of a cool temperate and highly seasonal paleoclimate with short warm dry summers and long comparatively mild and probably wet winters temperature calculations are consistent with previous estimates from alaska s north slope and northeastern russia suggesting a low polar temperature gradient and a slight cooling trend during the middle to early late maastrichtian precipitation estimates for the growing season are low compared to overall wet climate predictions for the maastrichtian like other late cretaceous arctic floras the cantwell flora is classified herein as a polar broad leaved deciduous forest flora

analysis origin and significance of mineral matter in coal an updated review abstract the material classed as mineral matter in coal embraces crystalline mineral materials as well as a range of inorganic elements that occur in non crystalline form this review outlines the methods that may be used to evaluate the percentage of mineral matter for a coal sample as opposed to the ash yield and to identify the minerals their individual percentages and their modes of occurrence within the coal the principal techniques include low temperature oxygen plasma ashing quantitative evaluation of x ray diffraction data observation using optical microscopy and a combination of observation chemical analysis and in some cases mapping based on scanning electron microscopy and related methods a range of other techniques may also be used to provide additional information on particular mineral matter components processes responsible for mineral matter formation include detrital input biogenic activity and authigenic precipitation at different stages of the coal s depositional and post depositional history differential migration of non mineral inorganic elements may also occur in lower rank coals and expulsion of non mineral inorganics may take place with rank advance knowledge of the mineral matter may be of assistance in understanding the modes of trace element occurrence with implications for assessing possible environmental impacts and also the potential for recovery of economic products from coal the behaviour of different mineral matter components at high temperatures is also discussed as well as methods for mineralogical analysis of ashes and other coal utilization products information from mineral matter studies may provide an improved basis for understanding coal formation and for evaluating the response of particular coals to different combustion gasification and coking processes

unconfined alluvial flow processes recognition and interpretation of their deposits and the significance for palaeogeographic reconstruction abstract palaeogeographic interpretation of the sedimentary rock record depends on correct recognition from the preserved evidence of the processes responsible for transporting and depositing the sediment this in turn depends on robust knowledge transfer from previous workers and the successful exchange of ideas between workers requires consistent use of a well defined vocabulary we have identified serious breakdowns in all these interpretation steps in the case of terrestrial unconfined flow and its deposits and these failures are leading to unreliable environmental and climatic interpretation this is significant because such alluvial deposits commonly form a majority of the rock record of continental environments working from the basic principles of geomorphology and fluid dynamics we have undertaken a wide ranging analysis of the nature of out of channel flow and from this make predictions about the characteristics of its deposits we identify the range of possible locations and conditions that lead to the development of unconfined flow review the processes operating in each case and examine the range of lithological features that can be produced by these processes this allows us to evaluate the reliability of the criteria claimed for identification of out of channel flow deposits and examine how our new insights might alter palaeoclimatic and palaeogeographic reconstructions published previously by others the sedimentary record of unconfined flows is much more diverse and complex than usually portrayed the received wisdom that the record of unconfined flow consists solely of upwards fining thin beds produced from shallow waning flows is shown to be flawed a wide range of lithofacies are possible and the variation in both flow steadiness and uniformity needs to be taken into account the previously published criteria for recognition of flows of this type are not diagnostic of process or location unconfined flow deposits cannot reliably be identified from grain size or bed thickness similar lithofacies may develop in a wide range of geomorphic and climatic settings because the deposits solely reflect the local flow conditions and sediment availability we recommend that the terms sandflat and sheetflood should not be used in sedimentological accounts because there is no longer a safe informal usage for either contradictory application of these terms and lack of robust definitions is leading to significant misunderstanding of palaeogeography and process our analysis should improve reconstruction of past terrestrial environments because it reveals more clearly the true variety of possibilities for the occurrence of unconfined flow and the resultant deposits enhanced understanding of the inherent uncertainties and realisation of the wider range of plausible alternative explanations should help resolve apparent contradictions with independent indicators of climate or geographic position

coal rank variation in the bowen basin queensland abstract isoreflectance maps for selected stratigraphic horizons in the bowen basin show regular rank trends and there is general parallelism between reflectance contours and structural contours in the basin these features imply that coalification is due to a rise of temperature with increasing depth of burial depth reflectance profiles calculated from coal bearing horizons across the basin show that reflectance increases with depth and reflectance gradients increase with increasing reflectance coal rank in the bowen basin is interpreted to be due to increased temperatures due to burial under conditions of high geothermal gradient during the permo triassic

oxygen isotope evidence for upward cross formational porewater flow in a sedimentary basin near maximum burial abstract authigenic ankerite in the gas bearing mid permian aldebaran sandstone denison trough queensland australia has an anomalously light oxygen isotopic composition 18 o smow range 7 6 to 14 4 and exhibits a trend of 18o enrichment from the base to the top of the unit textural relationships together with burial and thermal modelling indicate that this carbonate precipitated at temperatures of about 100 to 140 c when the sequence approached maximum burial during the late triassic this implies that ankerite precipitated from porewater very depleted in 18o with respect to marine water 18 o smow 9 to 5 the formation of this deep relatively high temperature ankerite is difficult to reconcile with downward percolation of meteoric water at that time since the basin was then undergoing its first burial compactional cycle we interpret the ankerite to have precipitated from porewater expelled upward from the earliest permian reids dome beds this thick unit consisting mainly of high latitude continental sandstones mudrocks and coals was initially saturated with very 18o depleted meteoric water 18 o smow 17 partly derived from melted snow and ice and is likely to have undergone overpressuring during rapid burial at rates up to 1 km ma tectonically induced expulsion of connate meteoric porewater out of the reids dome beds took place as the sequence approached maximum burial prior to late triassic basin uplift this water was flushed upward through the overlying units retaining a modified meteoric isotopic signature which was recorded by the precipitating ankerite computer modelling of heat transport isotopic mass balance and water mixing quantitatively shows that this interpretation is viable lending support to the suggested mechanism of upward cross formational porewater flow deep in a sedimentary basin

the age of illite cement growth village fields area southern north sea evidence from k ar ages and 18o 16o ratios in this paper we describe k ar radiometric ages and oxygen isotope ratio measurements of illite cements from eolian sandstone samples of the permian lower leman sandstone formation rotliegendes group the samples come from a large about 100 100 km part of the southern north sea basin village fields area and from a range of burial depths 2 8 3 4 km subsea bed mean illite ages in the gas fields of ravenspurn north 164 ma 20 1 2 sgr n 11 hyde 161 ma 12 3 n 7 cleeton 155ma 20 2 n 3 and hoton 152 ma 14 0 n 14 fields and in two wells located in block 47 5a 162 ma 16 1 n 4 are all in the middle to late jurassic apart from two early cretaceous ages considered to represent unreliable analyses the m an for all ages is 158 ma 18 6 2 sgr n 39 we largely avoided contamination with old detrital k bearing minerals by careful sample selection and monitoring to a first approximation the assumptions of k ar dating appear to be fulfilled so the measured ages are likely to date illite cement precipitation oxygen isotope ratios measured on the dated illite samples show small but significant variations among fields and a weak correlation with depth during the middle jurassic when illite grew both k ar dating and oxygen isotope ratios are compatible with a regional middle to late jurassic phase of illite growth during which the mineral precipitated over a large area and over a range of temperatures governed by the depth of the formation at that time the age of illite cementa ion coincides with rifting which ultimately may have caused illite growth by driving pore water flow

origin of clay minerals in alluvial paleosols prince creek formation north slope alaska u s a influence of volcanic ash on pedogenesis in the late cretaceous arctic abstract paleosols formed from weathering of alluvial mudstones in the late cretaceous maastrichtian prince creek formation north slope alaska are dominated by detrital smectite discrete illite kaolinite chlorite quartz and pedogenic illite smectite i s mixed layer clays in the fine clay fraction 80 low bulk density phosphorus accumulation fe and al mass balance trends and the presence of fe al humus complexes in one paleosol profile is interpreted as evidence of andic soil properties and these paleosols are interpreted therefore as andept like alluvial soils these results demonstrate that clay mineralogical studies in conjunction with geochemical data of paleosols can be used to identify paleo andic soil properties which have not been widely recognized in the ancient rock record alternating wetting and drying conditions required to form pedogenic i s in these alluvial paleosols resulted from a highly seasonal moisture regime in the late cretaceous arctic

paleoclimate estimates and fire ecology immediately prior to the end cretaceous mass extinction in the frenchman formation 66ma saskatchewan canada abstract the fossil rich deposits of the uppermost maastrichtian 66 ma frenchman formation of southern saskatchewan canada provide a detailed continuous record of terrestrial ecosystem dynamics during the last half million years leading up to the end cretaceous mass extinction paleoenvironmental interpretations for the frenchman formation are here refined by the first absolute paleoclimate estimates for the late cretaceous of saskatchewan and by the placement of these climate estimates within a north american context climate estimates were calculated using leaf margin analysis and the climate leaf analysis multivariate program clamp derived from two independent plant macrofossil assemblages collected from the frenchman formation climate parameter estimates indicate that the maastrichtian climate of southern saskatchewan was subtropical to warm temperate with mean annual temperatures between 12 c and 14 c and with marked seasonality these results are comparable with estimates derived from other late campanian and maastrichtian paleofloras in the western interior basin although small variations among coeval localities were noted or determined overall the plant fossil assemblages from the two study localities support the paleoenvironmental interpretation of the frenchman formation as a swampy to lowland forest system with canopy forming deciduous conifers and a diverse angiosperm dominated mid canopy and understory an unexpected marked disparity in plant diversity was found between the two paleofloras despite the plant assemblages returning similar paleoclimate parameter estimates abundant in situ inertinite fossil charcoal deposits were found in association with the less diverse paleofloral site which contained only angiosperm fossils inertinite was absent from the deposits containing the more diverse paleoflora which contained a different composition of angiosperm and gymnosperm fossils fire is known to be a prevalent feature of late cretaceous deposits worldwide and modern angiosperm plants typically are the first to recover following fire disturbances we suggest that the two frenchman formation paleofloras represent different stages of secondary ecological succession following a disturbance by fire the identification of fire ecology in the fossil record may have important implications for understanding biodiversity patterns on small spatial and temporal scales immediately prior to the cretaceous mass extinction

a multi disciplinary perspective on habitat preferences among dinosaurs in a cretaceous arctic greenhouse world north slope alaska prince creek formation lower maastrichtian abstract the prince creek formation of northern alaska is the most abundant source of polar dinosaur remains in the world and now corroborating data from this well studied rock unit allow for making inferences about the paleoecological preferences for these extinct polar animals the rock unit records high latitude alluvial sedimentation and soil formation on a low gradient muddy coastal plain compound and cumulative andic entisols and inceptisols formed on levees point bars crevasse splays and along the margins of floodplain lakes ponds and swamps abundant organic matter carbonaceous root traces fe oxide depletion coatings and zoned peds indicate periodic waterlogging anoxia and gleying consistent with a high water table in contrast fe oxide mottles ferruginous and manganiferous segregations bioturbation and less common illuvial clay coatings indicate recurring oxidation and periodic drying out of some soils an integrated reconstruction of pedogenic processes and biota suggests that this ancient arctic coastal plain was influenced by seasonally fluctuating water table levels and floods and in distal areas marine waters four of the five bonebeds in this study are from more distal areas represented by lower delta plain facies while the fifth bonebed is from a more proximal part of the basin represented by a somewhat better drained coastal plain facies bonebeds in the distal areas are dominated by edmontosaurus sp while the more proximal bonebed is dominated by the remains of the ceratopsian pachyrhinosaurus perotorum the distribution of these bonebeds sedimentological facies paleosols and biota suggests that pachyrhinosaurus may have preferred more upland environments while edmontosaurus preferred lowland deltaic environments this distribution may be the result of physiological adaptation to the pronounced seasonality provided by polar terrestrial ecosystems in contrast to a preferred habitat distribution of these large herbivores the large predatory dinosaur nanuqsaurus hoglundi seems to have had a more ubiquitous distribution across the landscape

distribution and origin of minerals in high rank coals of the south walker creek area bowen basin australia the coals of the south walker creek area in the northern bowen basin with a vitrinite reflectance rvmax of 1 7 to 1 95 are among the highest rank coals currently mined in australia x ray diffraction studies have identified an unusual mineral variation through the vertical sequence with kaolinite rich assemblages typical of other australian coals at the top and bottom of the seam section and an illite chlorite assemblage resembling a metamorphic association in the middle calcite and ankerite are also abundant in parts of the vertical sequence diaspore is abundant in the middle section of the seam in some areas and paragonite dickite or nacrite occurs in some locations as well the distribution of the non carbonate mineral assemblages cross cuts the seam stratigraphy and appears to be primarily controlled by faults and other structural features integration of the mineral distribution with optical and electron microscope data on the coal and non coal bands chemical data from coal ash analysis and information from x ray micro tomography suggests that the illite chlorite and diaspore bearing assemblages resulted from hydrothermal effects associated with fluid migration through the middle part of the coal seam this is further confirmed by the development of metamorphic textures in a tonstein band also altered to illite and chlorite in the illite rich part of the seam section in contrast to a tonstein with more normal sedimentary textures and a kaolinite composition in the kaolinite rich upper part of the seam detailed studies of cleat mineralisation suggest that fluids rich in ca mg and al were introduced relatively early in the seam s post depositional history associated with heat flow sufficient to alter the minerals in the coal and tonstein in the affected part of the seam section the relatively uniform vitrinite reflectance profile observed through the seam section may indicate that the coal was already of high rank before the fluids were introduced or that any localised heat effects on the organic matter associated with the changes in clay mineralogy were overprinted by subsequent wider ranging rank advance processes

late cretaceous early tertiary palaeoclimates of northern high latitudes a quantitative view analyses of plant community structure vegetational and leaf physiognomy and growth rings and vascular systems in wood provide qualitative and quantitative data that can be combined to define non marine palaeoclimatic parameters with better resolution than is available from other principally sedimentological methods application of these techniques to cenomanian through paleocene floras from high palaeolatitudes 75 85 n indicates a polar light regime similar to that of the present plant data suggests cenomanian sea level mean annual air temperatures mats of 10 c and mats of 13 c 5 c and 6 7 c in the coniacian maastrichtian and paleocene respectively evapotranspirational stresses at sea level were low and precipitation was in most part uniform throughout the growing season in the cenomanian with possible seasonal drying occurring by the maastrichtian maastrichtian winter freezing was likely but periglacial conditions did not exist at sea level permanent ice was likely above 1700 m at 75 n in the cenomanian and above 1000 m at 85 n in the maastrichtian these near polar data provide critical constraints on global models of late cretaceous to early tertiary climates

paleoclimate reconstruction of the prince creek formation arctic alaska during maastrichtian global warming abstract the upper cretaceous maastrichtian prince creek formation of arctic alaska 82 85 n paleolatitude preserves successions of alluvial paleosols that are used to estimate mean annual precipitation map mean annual temperature mat and meteoric water oxygen isotope composition for the prince creek formation the highest map estimates range between 1000 and 3900 mm yr and the lowest range between 350 and 1200 mm yr the precipitation variability derived from stable carbon isotope analysis occurs on a time scale of 104 years map values agree with previous interpretations from fossil pollen pedological features soil types vegetation composition sedimentological indicators and clamp estimates that suggest high precipitation amounts and high humidity despite the considerable uncertainty with mat proxies our values are consistent with warm month mean temperatures obtained previously from paleobotanical data the 18o of smectite from bentonite beds clusters around 5 0 vsmow the 18o of meteoric water calculated from bentonitic smectite is 23 vsmow assuming a mean annual temperature of 6 3 c which is slightly more 18o depleted than meteoric water calculated from pedogenic siderite in stratigraphically younger beds closer to the brooks range chronostratigraphic correlation with the lower cantwell formation denali national park alaska 64 n paleolatitude suggests higher precipitation rates and highly 18o depleted precipitation in the late cretaceous paleo arctic compared to central alaska these data are consistent with previous studies that suggest a warmer and moister greenhouse earth and an intensified hydrological cycle that enhanced latent heat transport resulting in increased rainout effects

early diagenetic siderite as an indicator of depositional environment in the triassic rewan group southern bowen basin eastern australia early concretionary and non concretionary siderites are common in subsurface triassic sandstones and mudrocks of the rewan group southern bowen basin a detailed petrological and stable isotopic study was carried out on these siderites in order to provide information on the depositional environment of the host rocks the siderites are extremely pure containing 85 97 mol feco3 and are commonly enriched in manganese 13c pdb values are highly variable ranging from 18 4 to 2 9 whereas 18o pdb values are very consistent ranging from 14 0 to 10 2 mean 11 9 1 0 the elemental and oxygen isotopic composition of the siderites indicates that only meteoric porewaters were involved in siderite formation implying that host rocks accumulated in totally non marine environments the carbon isotopic composition of the siderites is interpreted to reflect mixing of bicarbonate carbon dioxide generated by methane oxidation and methanogenesis very low 13c values demonstrate that contrary to current views highly 13c depleted siderite can be produced at shallow burial depths in anoxic non marine sediments

palaeobotanical evidence for a warm cretaceous arctic ocean the cretaceous period was a time of global warmth1 4 mid cretaceous equatorial temperatures were similar to today s5 but the equator to pole temperature gradient is the subject of some controversy5 7 although it is unlikely that the poles were ice free8 10 fossil evidence3 5 11 12 indicates that near polar temperatures were much higher than they are today little is known moreover about oceanic poleward heat transport and this makes it hard to model the cretaceous climate or to evaluate the extent to which it provides an analogue for a greenhouse world warmed by increased atmospheric co2 alone here we use relationships between leaf physiognomy such as shape and size and modern climate to determine cretaceous climate conditions in the arctic region from fossil leaves we find that the arctic ocean was relatively warm remaining above 0 c even during the winter months this implies that there was significant poleward heat transport during all seasons

composition porosity and reservoir potential of the middle jurassic kashafrud formation northeast iran abstract in the kopet dagh basin of iran deep sea sandstones and shales of the middle jurassic kashafrud formation are disconformably overlain by hydrocarbon bearing carbonates of upper jurassic and cretaceous age to explore the reservoir potential of the sandstones we studied their burial history using more than 500 thin sections supplemented by heavy mineral analysis microprobe analysis porosity and permeability determination and vitrinite reflectance the sandstones are arkosic and lithic arenites rich in sedimentary and volcanic rock fragments quartz overgrowths and pore filling carbonate cements calcite dolomite siderite and ankerite occluded most of the porosity during early to deep burial assisted by early compaction that improved packing and fractured quartz grains iron oxides are prominent as alteration products of framework grains probably reflecting source area weathering prior to deposition and locally as pore fills minor cements include pore filling clays pyrite authigenic albite and k feldspar and barite existing porosity is secondary resulting largely from dissolution of feldspars micas and rock fragments with some fracture porosity porosity and permeability of six samples averages 3 2 and 0 0023 md respectively and 150 thin section point counts averaged 2 7 porosity reflectance of vitrinite in eight sandstone samples yielded values of 0 64 0 83 in the early mature to mature stage of hydrocarbon generation within the oil window kashafrud formation petrographic trends were compared with trends from first cycle basins elsewhere in the world inferred burial conditions accord with the maturation data suggesting only a moderate thermal regime during burial some fractures iron oxide cements and dissolution may reflect cenozoic tectonism and uplift that created the kopet dagh mountains the low porosity and permeability levels of kashafrud formation sandstones suggest only a modest reservoir potential for such tight sandstones fractures may enhance the reservoir potential

kinematics of basin development during the transition from terrane accretion to strike slip tectonics late cretaceous early tertiary cantwell formation south central alaska the cantwell basin was formed during late cretaceous time in the suture zone between the wrangellia composite terrane and the former continental margin of southern alaska the late cretaceous 80 70 ma lower cantwell formation represents the initial fill of this basin and includes 4000 m of sedimentary rock between maastrichtian and late paleocene time 70 60 ma rocks of the lower cantwell formation were deformed by nearly eastwest trending folds and north vergent thrust faults this deformation can be linked to the northward accretion and suturing of the wrangellia composite terrane to southern alaska during late paleocene to early eocene time 60 55 5 ma at least 2750 m of volcanic rocks of the upper cantwell formation were deposited above the folded lower cantwell formation new 40ar 39ar ages for the upper cantwell formation range from 59 8 0 2 to 55 5 0 2 ma and reveal that the unconformity between the lower and upper cantwell formations represents a 10 20 million year hiatus following volcanism the cantwell formation was crosscut by northeast trending folds northwest trending normal faults north trending left lateral slip faults northeast trending reverse faults and east trending right lateral slip faults these structures are consistent with northwest southeast compression in a zone of right lateral simple shear along a fault with the same trend east northeast as that of the present mckinley strand of the denali fault system cantwell basin kinematics are compatible with an escape tectonics model for south central alaska whereby the cantwell basin was formed folded and partially uplifted during northward terrane accretion and suturing and was deformed again during the westward transfer of terranes along right lateral strike slip fault systems

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

palaeoenvironment and ecology of the middle cretaceous grebenka flora of northeastern asia the grebenka flora from the main exposure of the albian cenomanian krivorechenskaya formation in northeastern russia represents a range of plant communities from pioneer to mature forest that grew close to the mid cretaceous north pole 72degreesn the diversity of this flora is dominated by angiosperms followed by conifers ferns and other plant groups the age is constrained by ar 40 ar 39 analyses of associated volcaniclastics similar to 96 5 ma coupled with biostratigraphic correlation of the plant bearing non marine beds with marine units of the krivorechenskaya formation and the overlying dugovskaya formation limited palaeosol development and pronounced episodic floodplain aggradation indicate that the 100 m thick plant bearing volcaniclastic floodplain succession was deposited rapidly resulting in excellent trapping and preservation of the plant communities but dilution of the palynoflora analysis of the megaflora 100 foliage taxa plus woods and fructifications provides a snapshot of the mid cretaceous climate and offers reliable quantitative climatic signals of conditions near the mid cretaceous north pole multivariate analysis of leaf physiognomy climate leaf analysis multivariate program on the whole flora suggests that the plants experienced a mean annual temperature of 13 0 1 8degreesc and a cold month mean temperature of 5 5 3 3degreesc however analyses of individual florules yield slightly different results that help constrain the uncertainties inherent in such an approach these and other foliar physiognomic data are compared across the arctic less

experimental determination of fe isotope fractionation between aqueous fe ii siderite and green rust in abiotic systems abstract iron isotope fractionation between aqueous iron and siderite has been measured using abiotic synthesis experiments at 20 c applying a rayleigh distillation model to three experiments in which siderite feco3 was continuously precipitated from solutions over the course of tens of hours the derived fractionation factor is 103ln fe ii siderite 0 48 0 22 2 this experimentally determined fractionation factor is significantly smaller by 1 5 than that calculated from vibrational frequencies and mossbauer shifts geochim cosmochim acta 64 2000 849 865 geochim cosmochim acta 65 2001 2487 2497 and lies on the high end of that inferred from natural mineral assemblages where the fe ii aq siderite fractionation factor was inferred to lie between 1 7 and 0 3 contrib mineral petrol 144 2003 523 547 the measured fe ii aq siderite fractionation from this study suggests that siderite from archean and proterozoic rocks which have moderately negative 56fe values 1 5 to 0 5 may reflect precipitation from fe ii aq whose origin was hydrothermal in contrast natural siderites that have higher 56fe values apparently require non hydrothermal sources of fe and or different pathways of formation or may reflect the effects of cation substitution on the fe ii aq carbonate fractionation factor

site characterization in ismailia egypt using seismic ambient vibration array abstract seismic ambient vibration array measurements were carried out at seven sites in ismailia egypt in order to obtain one dimensional 1d shear wave velocity vs profiles and horizontal to vertical spectral ratios hvsr we applied the spatial autocorrelation spac method to the ambient vibration data for the estimating rayleigh wave dispersion curves and obtained 1d vs profiles the deeper parts 90 350 m of the estimated models have vs values ranging between 500 and 700 m s while the subsurface parts have vs varying between 140 and 200 m s the averaged vs in the upper 30 m based on the results indicate that site classes of all the sites are classified as c or d according to nehrp soil classification the computed site amplification factors derived from the estimated vs profiles show that the resonant frequencies at sites on the east side of the suez canal are below 1 hz while those at sites on the west side vary between 1 and 2 hz indicating the difference of subsurface geology across the suez canal the hvsr curves at each site are generally similar for all sensors indicating nearly flat subsurface layers beneath each site we also compared the dominant frequencies of hvsrs and those derived from 1d amplification factors the comparisons show that both the frequencies are similar to each other but there are slight differences possibly due to the lack of deeper sedimentary layer structures and lower resolution of hvsrs in the lower frequency range indicating the importance of further ambient vibration survey with broadband sensors the results show that the combination of spac and hvsr methods is advantageous to estimate proper vs profiles to evaluate site effects for earthquake disaster mitigation

latest cretaceous maastrichtian climate of the koryak upland of north east russia based on a quantitative analysis of a palaeo polar flora we describe fossil plant assemblages from the late maastrichtian kakanaut formation of the koryak upland north east of russia which represent a high 75on palaeolatitude flora the flora contains about 40 species including liverworts horsetails ferns cycadophytes ginkgos conifers and angiosperms angiosperms and conifers predominate and unusually the flora contains typical cretaceous taxa admixed with elements that are more characteristic of the paleocene reconstruction of the palaeoclimate in the kakanaut area was made using the climate leaf analysis multivariate program clamp employing a recently developed calibration that yields 23 different climate variables analysis was made based on 21 morphotypes of woody dicotyledonous plants from the kakanaut flora the analysis indicated a mean annual temperature of 12 2 2 0 c a warmest month mean temperature of 20 6 2 5 c a coldest month mean temperature of 4 8 3 2 c the growing season lasted approximately 7 months during which there was almost 1 m of precipitation this and other indicators relative humidity vapour pressure deficit and potential evapotranspiration all suggest a year round humid regime the winter temperatures suggest occasional mild frosts in this near sea level setting so that at higher elevations freezing conditions would have been more persistent these results throw new light on the living and breeding conditions of diverse latest cretaceous arctic dinosaur populations as represented by numerous skeletal and egg remains associated with the plants

facies relationships and cyclicity of high latitude late permian coal measures bowen basin australia the late permian moranbah coal measures are developed throughout the northern and central bowen basin eastern australia and are subject to large scale opencut coal mining activity they were deposited in a rapidly subsiding retroarc foreland basin during frequent base level changes contemporaneous compressive deformation and volcanism facilitated the supply of abundant volcanoclastic sediments resulting in rapid but punctuated basinal aggradation to the south and east transgressive regressive cycles were marked by the inter digitation of paralic shallow marine and alluvial strata lonestones dropstones are common within the marine deposits and are attributed to ice rafting indicative of a cold climate depositional regime two basin wide chronostratigraphic units the p tuff bed and the harrow creek superseam have been used to evaluate the facies architecture of the stratigraphic interval they enclose the lithofacies mosaic of the 25 75 m thick sequence has been examined by means of 26 widely distributed coreholes and two detailed district scale studies based around the moranbah goonyella and german creek minesites eight alluvial shallow marine facies associations have been recognised their architectural and temporal relationships allow the accurate reconstruction of the coal bearing depositional system two dissimilar stacked depositional systems tracts a organics and b clastics are recognised the p tuff bed is enclosed by facies of tract a forming a thick low ash coal bearing interval which was emplaced essentially synchronously across the basin it represents a time of clastic sediment starvation when basin wide peat mire accumulation prevailed four similar extensive coal bearing intervals within the moranbah coal measures are also considered to represent basin wide episodes of peat accumulation this pattern is in strong contrast to traditional views of coal measure development which argue that coals formed within a contemporary facies mosaic in which fluvial channels levees and crevasse splays were also represented the second depositional systems tract b is characterised by clastic packages dominated by large scale up to 4 km wide and 50 m thick sandstone bodies deposited by low sinuosity trunk river systems flanked by substantial crevasse splay deposits up to 3 km wide and 30 m thick it represents the product of catastrophic flooding events the cyclothemic succession of systems tracts a and b is interpreted in terms of eustatic sealevel cycles the tract a coal bearing intervals represent relative sealevel lowstands systems tract b represents relative sea level highstand with its lower interval at german creek to the south consisting of paralic and marine facies the cycles had durations in the order of 400 to 600 ky and are considered to represent 4th order sealevel cycles of the permian period

update and sensitivity analysis of the neo deterministic seismic hazard assessment for egypt abstract the main goal of this work is to provide an update on the seismic hazard maps available for egypt that incorporates the results of recent studies i e revised historical earthquake catalogs morphostructural zonation data mz revised focal mechanism solutions and mechanical models of the lithospheric structure this is done within the framework of the neo deterministic seismic hazard assessment ndsha procedure that may effectively accommodate any reliable new information to adequately compute the earthquake ground motion maps i e pga pgv and pgd furthermore with the set of relevant scenario earthquakes this work provides a large dataset of synthetic seismograms particularly important for the areas that suffer from the endemic lack of useful strong motion time histories such as egypt setting the base toward detailed and comprehensive seismic microzonation studies ndsha aims to supply an envelope value in other words a value that should not be exceeded therefore it is immediately falsifiable and verifiable a sensitivity analysis based on the different ground motion maps computed adopting different a models for the earthquake source process b mechanical models of the crust and c mapmaker s preconceptions e g different seismotectonic models is provided the maps of difference and ratio between various ground motion maps computed for different variants are shown and discussed in order to explore the influence of using various input models the results provide the potential users with an adequate spectrum of choices and reliably assess and clearly communicate the possible uncertainties the availability of a wide spectrum of hazard maps is a prerequisite to supply valuable information for the significant improvement of a seismic code

north american nonmarine climates and vegetation during the late cretaceous abstract analyses of physiognomy of late cretaceous leaf assemblages and of structural adaptations of late cretaceous dicotyledonous woods indicate that megathermal vegetation was an open canopy broad leaved evergreen woodland that existed under low to moderate amounts of rainfall evenly distributed through the year with a moderate increase at about 40 45 n many dicotyledons were probably large massive trees but the tallest trees were evergreen conifers megathermal climate extended up to paleolatitude 45 50 n mesothermal vegetation was at least partially an open broad leaved evergreen woodland perhaps a mosaic of woodland and forest but the evapotranspirational stress was less than in megathermal climate some dicotyledons were large trees but most were shrubs or small trees evergreen conifers were the major tree element some mild seasonality is evidenced in mesothermal woods precipitational levels probably varied markedly from year to year northward of approximately paleolatitude 65 n evergreen vegetation was replaced by predominantly deciduous vegetation this replacement is presumably related primarily to seasonality of light the southern part of the deciduous vegetation probably existed under mesothermal climate comparisons to leaf and wood assemblages from other continents are generally consistent with the vegetational climatic patterns suggested from north american data limited data from equatorial regions suggest low rainfall late cretaceous climates except probably those of the cenomanian had only moderate change through time temperatures generally appear to have warmed into the santonian cooled slightly into the campanian and more markedly into the maastrichtian and then returned to santonian values by the late maastrichtian the early eocene was probably warmer than any period of the late cretaceous latitudinal temperature gradients were lower than at present for the campanian and maastrichtian a gradient of about 0 3 c 1 latitude is inferred equability was high a mean annual range of temperature of about 8 c is inferred for paleolatitude 51 56 n during the campanian most late cretaceous plants evolved in a climate characterized by absence of freezing and low to moderate amounts of precipitation a brief low temperature excursion and a major long lasting increase in precipitation occurred at the cretaceous tertiary boundary in megathermal climates these events selected for plants that could exist in rainforest environments in mesothermal climates deciduousness and contamitant structural adaptations were selected the events at the cretaceous tertiary boundary had a major and long lasting impact on the evolution of land plants and their ecosystems low precipitation at low to middle late cretaceous latitudes is suggested to be the result of high levels of atmospheric co2 which in turn are probably related to inability of warm saline oceans to store large amounts of carbon conditions appear to have rapidly changed at the cretaceous tertiary boundary when oceanic circulation and stratification may have been fundamentally altered after the boundary the oceans were apparently able to store much greater amounts of carbon and the oceans withdrew large amounts of co2 from the atmosphere in turn more precipitation fell at low to middle latitudes the resulting high biomass vegetation formed a second major carbon reservoir to keep atmospheric co2 low relative to the late cretaceous changes in oceanic and atmospheric circulation probably resulted from some factor external to the ocean atmosphere system

sandstone petrofacies expressions of multiphase basinal tectonics and arc magmatism permian triassic north bowen basin australia abstract modal analyses of 209 sandstone samples from the permian triassic succession of the northern bowen basin eastern australia identify two stratigraphically and compositionally distinct petrofacies the lower to mid upper permian back creek group is characterised by petrofacies a which is quartz rich q82f8l10 it was sourced primarily from cratonic basement terranes to the west where relief was subdued and the quartz content of the sandstones may also reflect some reworking in the marine realm with a consequent loss of labile grains petrofacies b is volcanolithic and characterises alluvial sediments of the upper permian blackwater and lower triassic rewan groups it was sourced from an undissected to transitional magmatic arc provenance located in the contemporary new england orogen to the east which supplied abundant pyroclastic debris to the depositional complex petrofacies b of the northern bowen basin was derived primarily from felsic volcanics compared to an intermediate association recorded for the southern basinal sector indicating significant along arc variation in volcanic style as a consequence its framework grain population is enriched in quartz and is not readily accommodated in the schemes of provenance interpretation currently in use the consistency of framework detrital modes for sandstones distributed throughout the blackwater group q24f10l66 allows the recognition of subpetrofacies b1 and shows that the volcanism associated with the magmatic arc system was remarkably uniform in character and activity during deposition of the entire group the magmatic arc delivered almost identical sedimentary debris over a period of some 9 my in the late permian relative enrichment of quartz within the early triassic rewan group q49f6l45 relative to the blackwater group discriminates subpetrofacies b2 and is attributed to a climatic change and shift in palaeotemperature at the permian triassic boundary the contact between the marine back creek group petrofacies a and the coal bearing blackwater group petrofacies b represents an abrupt switch in provenance with little or no evidence of source mixing the boundary marks the onset of volcanism and associated tectonic uplift in the northern part of the new england orogen to the east sediment from the new source prograded rapidly westwards across the basin coincident with regression direct evidence of contemporaneous volcanism is widespread in the blackwater group as shown by tuffs and tonsteins which are distributed throughout the entire late permian succession

stable isotope evidence for the origin of diagenetic carbonate minerals from the lower jurassic inmar formation southern israel the oxygen isotope compositions of diagenetic carbonate minerals from the lower jurassic inmar formation southern israel have been used to identify porewater types during diagenesis changes in porewater composition can be related to major geological events within southern israel in particular saline brines played an important role in late pliocene pleistocene dolomitization of these rocks diagenetic carbonates included early siderite 18osmow 24 4 to 26 5 13cpdb 1 1 to 0 8 late dolomite ferroan dolomite and ankerite 18osmow 18 4 to 25 8 13cpdb 2 1 to 0 2 and calcite 18osmow 21 3 to 32 6 13cpdb 4 2 to 3 2 the petrographic and isotopic results suggest that siderite formed early in the diagenetic history at shallow depths the dolomitic phases formed at greater depths late in diagenesis crystallization of secondary calcite spans early to late diagenesis consistent with its large range in isotopic values a strong negative correlation exists between burial depth temperature and the oxygen isotopic compositions of the dolomitic cements in addition the 18o values of the dolomitic phases in the northern negev and judea mountains are in isotopic equilibrium with present formation waters this behaviour suggests that formation of secondary dolomite post dates the tectonic activity responsible for the present relief of southern israel upper miocene to pliocene and that the dolomite crystallized from present formation waters such is not the case in the central negev in that locality present formation waters have much lower salinities and 18o values indicating invasion of freshwater and are out of isotopic equilibrium with secondary dolomite recharge of the inmar formation by meteoric water in the central negev occurred in the pleistocene and halted formation of dolomite

diagenesis and isotopic evolution of porewaters in the alberta deep basin the falher member and cadomin formation abstract diagenesis and porewater evolution in the alberta deep basin have been studied by combining results from petrologic stable isotope and fluid inclusion analyses of diagenetic minerals four stages of diagenesis and porewater evolution corresponding to burial and subsequent uplift and erosion have been identified in the falher member of the spirit river formation and the cadomin formation stage 1 deposition and burial is marked by early precipitation of hematite siderite or chlorite and the dissolution of unstable detrital grains followed by later albitization precipitation of illite and local calcite cement and pressure solution of chert grains during this stage 18o values of porewaters in the falher member increased from 10 3 to 3 infiltration of saline fluids from pre cretaceous units may have produced porewaters in the cadomin formation with 18o values as high as 4 to 7 stage 2 maximum burial and relief is dominated by precipitation of quartz druse in conglomerates and horizontal fractures porefluids during stage 2 had 18o values of 3 at 190 c 2 3 wt dissolved solids in the falher member and at 150 c in the cadomin formation during stage 3 uplift and erosion precipitation of dickite occurred in both the falher member and the cadomin formation from evolved meteoric water as temperatures and 18o values of the porewater decreased in addition precipitation of ankerite and calcite was initiated in the falher member as the influx of evolved meteoric water continued finally in stage 4 maximum generation of methane from interbedded coals methane saturation of the porespaces marked the end of diagenesis in the down dip gas saturated part of the deep basin

thrust top basin formation along a suture zone cantwell basin alaska range implications for development of the denali fault system the cantwell formation consists of a lower sedimentary sequence as much as 4000 m thick and an upper volcanic sequence with a maximum thickness of 3750 m that was deposited in the cantwell basin south central alaska previous to this study the cantwell basin was interpreted as a paleogene nonmarine mainly fluvial pull apart basin that formed in response to dextral strike slip displacement on the denali fault system this study proposes that the cantwell basin formed as part of the mesozoic accretionary phase of deformation prior to the development of the cenozoic postaccretionary denali fault system our reinterpretation is based on several new lines of data 1 age new data based on palynologic analyses of 135 fine grained samples indicate that the lower cantwell formation was deposited during the late campanian and early maastrichtian on the basis of previous regional tectonic studies and this new age constraint the formation of the cantwell basin was coeval with regional late cretaceous shortening associated with accretionary tectonics in southern alaska 2 depositional systems our analysis of the cantwell formation demonstrates that sedimentation occurred mainly in stream dominated alluvial fan axial braided stream and lacustrine settings these depositional systems were strongly influenced by a southward dipping asymmetric basin floor the presence of abundant terrestrially derived organic material together with palynological assemblages that include marine dinoflagellates and the associated presence of oncolites may be suggestive of a time of marginal marine influence during the deposition of the upper part of the lower cantwell formation the late campanian to early maastrichtian timing of this possible marine influence is within the range of the bearpaw transgressive event of the cordilleran foreland basin and allows for regional stratigraphic correlation of the cantwell basin with other sedimentary basins in northwestern north america 3 structural controls on basin formation mapping of intraformational angular unconformities and progressively tilted strata along the southern margin of the cantwell basin provides direct evidence that thrust fault deformation and lower cantwell formation sedimentation were synchronous distinctive cantwell formation conglomerate clasts derived from the uplifted hanging walls of nearby thrust sheets adjacent to the southern basin margin also support a syndepositional thrusting interpretation provenance data and the concentration of proximal alluvial fan deposits along the northwestern basin margin adjacent to the hines creek fault indicate that it too was active during deposition of the cantwell formation on the basis of the new data the cantwell basin is interpreted to have formed as a thrust top basin i e piggyback basin along the late cretaceous suture zone between the accreting wrangellia composite terrane and the north american continental margin in contrast to previous studies this reinterpretation of the formation of the cantwell basin implies that the lower cantwell formation is not a synorogenic deposit directly associated with strike slip displacement along the denali fault system therefore the cantwell basin cannot be used to constrain the timing for the early development of the denali fault system

isotopic composition of siderite as an indicator of depositional environment compilation of available oxygen and carbon isotopic data for siderites from different depositional environments indicates that marine and continental siderites are characterized by distinctive compositional fields the most notable difference between the fields is the generally higher 13 c values of continental vs marine siderites this difference appears to reflect the fact that marine sediments generally undergo a more extensive period of sulfate reduction than do the continental sediments in which siderite forms analysis of siderite geochemistry may assist in determination of depositional environment in cases where the available sedimentological evidence is ambiguous

timing and chemistry of fluid flow events in the lawn hill platform northern australia mudrocks and carbonates of the isa superbasin in the lawn hill platform in northern australia host major base metal sulfide mineralization including the giant strata bound century zn pb deposit mineral paragenesis stable isotope and k ar dating studies demonstrate that long lived structures such as the termite range fault acted as hot fluid conduits several times during the paleoproterozoic and mesoproterozoic in response to major tectonic events illite and chlorite crystallinity studies suggest the southern part of the platform has experienced higher temperatures up to 300 degrees c than similar stratigraphic horizons in the north the irregular downhole variation of illite crystallinity values provides further information oil the thermal regime in the basin and shows that clay formation was controlled not only by temperature increase with depth but also by high water rock ratios along relatively permeable zones k ar dating of illite in combination with other data may indicate three major thermal events in the central and northern lawn hill platform lit 1500 1440 to 1400 and 1250 to 1150 ma this study did not detect the earlier century base metal mineralizing event at 1575 ma 1500 ma ages are recorded only in the south and correspond to the age of the late isan orogeny and deposition of the lower roper superbasin they may reflect exhumation of a provenance region the 1440 to 1300 ma ages are related to fault reactivation and a thermal pulse at similar to 1440 to 1400 ma possibly accompanied by fluid flow with subsequent enhanced cooling possibly due to thermal relaxation or further crustal exhumation the youngest thermal and or fluid flow event at 1250 to 1150 ma is recorded mainly to the cast of the tern lite range fault and may be related to the assembly of the rodinian supercontinent fluids in equilibrium with illite that formed over a range of temperatures at different times in different parts of the platform have relatively uniform oxygen isotope compositions and more variable hydrogen isotope compositions delta o 18 3 5 9 7 parts per thousand v smow delta d 94 to 36 parts per thousand v smow the extent of the 180 enrichment and the variably depleted hydrogen isotope compositions suggest the illite interacted with deep basin hypersaline brines that were composed of evaporated seawater and or highly evolved meteoric water siderite is the most abundant iron rich gangue phase in the century zn pb deposit which is surrounded by all extensive ferroan carbonate alteration halo modeling suggests that the ore siderite formed at temperatures of 120 degrees to 150 degrees c whereas siderite and ankerite in the alteration halo formed at temperatures of 150 degrees to 180 degrees c the calculated isotopic compositions of the fluids are consistent with o 18 rich basinal brines and mixed inorganic and organic carbon sources 6180 3 10 parts per thousand v smow delta c 13 7 to 3 parts per thousand v pdb in the northeast lawn hill platform carbonate rich rocks preserve marine to early diagenetic carbon and oxygen isotope compositions whereas ferroan carbonate cements in siltstones and shales in the desert creek borehole are o 18 and c 13 depleted relative to the sedimentary carbonates the good agreement between temperature estimates from illite crystallinity and organic reflectance 160 degrees 270 degrees c and inverse correlation with carbonate delta o 18 values indicates that organic maturation and carbonate precipitation in the northeast lawn hill platform resulted from interaction with the 1250 to 1150 ma fluids the calculated isotopic compositions of the fluid are consistent with evolved basinal brine delta o 18 5 1 9 4 parts per thousand v smow delta c 13 13 2 to 3 7 parts per thousand v pdb that contained a variable organic carbon component from the oxidation and or hydrolysis of organic matter in the host sequence the occurrence of extensive o 18 and c 13 depleted ankerite and siderite alteration in desert creek is related to the high temperature of the 1250 to 1150 ma fluid flow event in the northeast lawn hill platform in contrast to the lower temperature fluids associated with the earlier century zn pb deposit in the central lawn hill platform

cretaceous tertiary palynofloral perturbations and extinctions within the aquilapollenites phytogeographic province a combination of detailed intermediate and large scale stratigraphic perspectives is necessary to understand the driving mechanisms for floral change across the cretaceous tertiary k t boundary because short term physical and biotic events occur within longer term trends most maastrichtian palynofloral extinctions have been identified within the northern circumpolar supra continental aquilapollenites province in mid continental north america the presence of a physically defined k t boundary provides opportunities to examine contemporaneous terrestrial palynofloras over a latitudinal also approximately paleolatitudinal distance of 3200 km seventy five percent of last appearances occur before the k t boundary at high latitudes and must have been caused by ongoing terrestrial processes palynofloral events directly associated with the k t boundary include both local last appearances and inferred extinctions and synchronous and diachronous changes in relative abundances two different styles of factors are reflected in these events the first possibly attributable to chemical or other profound atmospheric perturbations associated with the worldwide distribution of the fireball layer of the k t claystone resulted in extinctions of angiosperm with a zoophilous pollination strategy the second factor possibly reflecting energy released during the deposition of ballistically transported impact debris or hackly ejecta layer of the boundary claystone resulted in the selective northward attenuating removal of the canopy vegetation best documented for southwestern canada which was succeeded by a fern dominated vegetation in mid continental north america these consequences of the boundary event were mediated by independent preexisting circumstances climate regional and through time local depositional environment and ongoing background extinctions and origins

the evolution of latitudinal temperature gradients from the latest cretaceous through the present abstract latitudinal temperature gradients are a defining characteristic of the climate system using thermometric indicators including 18o plant and animal fossils glycerol dialkyl glycerol tetraether gdgt proxies and clumped isotope estimates we document marine and terrestrial temperature gradients for the latest cretaceous late paleocene early eocene early oligocene pliocene and recent the changes in gradients reflect the transition greenhouse to icehouse conditions the evolution of latitudinal temperature gradients in marine and terrestrial realms are similar but has some distinctive differences marine temperatures are generally warmer than those on land except for the late paleocene early eocene the marine records show distinct inflection points at 30 and 50 latitude indicating the existence of frontal systems in the ocean except for the late paleocene early eocene the marine records show an increasingly steeper trend from latest cretaceous through recent being most pronounced after the early oligocene greenhouse icehouse transition this trend reflects the increasing intensity of high latitude and polar cooling as the icehouse state developed during the late paleocene early eocene the oceans were characterized by slightly warmer tropics and much warmer higher latitudes than at present the continents have generally had tropical temperatures like those of today varying by

anomalously low δ18o values of high latitude permo triassic paleosol siderite abstract the most severe extinction in earth history occurred during a time of extreme climate change caused in part by a massive release of carbon into the atmosphere isotopic measurements of siderite occurring in paleosols during intervals of global warming suggest high latitude depletions in 18 o of precipitation often attributed to an amplified hydrologic cycle here late permian and early triassic paleosol siderite from alaska antarctica eastern australia siberia and south africa indicate similar or greater meridional gradients in siderite 18 o compared to other past warm intervals an isotope tracer enabled version of the global environmental and ecological simulation of interactive systems genesis general circulation model gcm was used to compare to siderite 18 o data the model when deriving siderite 18 o at a specified paleoatmospheric co 2 concentration of 12 7 the preindustrial atmospheric level pal matches a small subset of relatively less depleted high latitude siderites but does not produce the conditions necessary to explain the most depleted siderite 18 o values siderite has been thought to record mean annual precipitation 18 o though this study suggests that many may not a seasonal bias where siderite growth occurs in the summertime in wetlands that receive most of their recharge from melting winter precipitation may be responsible genesis indicates soil moisture recharge during the spring ahead of the rainy season for high latitude permo triassic pt siderite localities that reach below freezing winter temperatures drainage from high altitude regions throughout the growing season may also be responsible biological cloud feedbacks and monsoon related amount effects are not likely the cause for low siderite 18 o because the enrichment of water vapor 18 o associated with warming is too significant

illitization and paleothermal regimes in the middle ordovician st peter sandstone central michigan basin k ar oxygen isotope and fluid inclusion data hydrocarbon reservoirs occur in the middle ordovician st peter sandstone in the central michigan basin at depths of 1 5 3 5 km and are diagenetically altered latest diagenetic cements include saddle dolomite pervasive microcrystalline illite and chlorite and quartz a k ar and 18o 16o study of the fine grained authigenic illite in 25 samples from 16 wells covering a large area within the basin yields k ar ages ranging from 367 to 322 ma and dgr18o values between 12 7 and 16 9 pmil smow the dgr18o values of diagenetic quartz overgrowths range from 15 2 to 18 9 pmil fluid inclusion temperatures in the quartz cement range from 70 to 170 c reflecting multiple generations of diagenetic quartz and or precipitation over m st of the diagenetic history reequilibrated fluid inclusions in the saddle dolomite cement yield temperatures ranging from 90 to 150 c a regionally significant episode of illitization occurred during the late devonian mississippian temperatures of illite formation are indirectly estimated to be in the range of 125 170 c and most paleodepths of illitization are between 2 8 and 3 2 km these results imply that 1 illite formed from 18o rich fluids and 2 elevated geothermal gradients i e greater than 34 c km existed in the michigan basin in the late paleozoic the k ar ages and the dgr18o values are not correlated to present depths of the samples or paleodepths of illitization illites with young ages and low dgr18o values tend to be geographically distributed along the north south branch of the buried precambrian rift the dgr18o values of the diagenetic quartz follow a similar trend the spread of illite k ar ages and dgr18o values and their geographic distribution are best explained as reflecting abnormally high thermal regimes in the part of the basin located above the presumably highly fractured basement along the rift

new quantitative palaeocolimate data for the late cretaceous arctic evidence for a warm polar ocean abstract physiognomic analysis of four taphofloras one from the coniacian of n alaska one from the coniacian of kamchatka one from the turonian of kamchatka and one from the turonian of novaya sibir island using the clamp technique of wolfe 1993 yielded quantitative data on the mean annual warm month mean and cold month mean temperatures the length of the growing season mean annual precipitation mean growing season precipitation mean monthly growing season precipitation and the precipitation during the three consecutive driest months these new results represent the first application of multivariate statistical analysis of foliar physiognomy to determine palaeoclimatic parameters clamp to arctic cretaceous floras and demonstrate its robustness even in the context of vegetation which has no living analogues these new estimates were comparable to those from previous quantitative or qualitative sedimentological or palaeobotanical data where they were available but offer greater measurable precision the results also suggest that an arctic ocean with a winter surface temperature of approximately 6 c maintained n alaska coastal temperatures above freezing locally reversing the equator to pole temperature gradient a phenomenon not seen in the northern proto pacific this anomalously warm arctic ocean could have been produced by marine poleward heat transport precipitation in alaska kamchatka and novaya sibir island was predicted to have been high e g 1760 mm yr in the coniacian of n alaska reflecting a very weak polar high pressure cell and substantially different precipitation patterns to present

coal petrography mineralogy elemental compositions and palaeoenvironmental interpretation of late carboniferous coal seams in three wells from the kozlu coalfield zonguldak basin nw turkey abstract a number of coal seams of late carboniferous age in the coal bearing karadon kozlu and alacaagzi formations have been mined in several deep underground mines in the zonguldak basin nw turkey for this study a total of 154 coal core samples were collected from three research wells that were drilled in the tectonically complex settings of the kozlu coalfield all the coal samples were studied by means of coal petrography mineralogy and geochemistry special attention was given to the compositions and origins of fracture cleat filling minerals that were identified by sem edx on polished blocks the coal seams investigated are of bituminous rank they are characterized by low total sulphur contents 1 0 on dry basis and high gross calorific values 22 5 40 2 mj kg on dry ash free basis whereas ash yields and volatile matter contents are variable x ray powder diffraction data indicate that the mineralogical compositions of the studied coal seams are rather similar and clay minerals along with quartz and carbonate minerals were identified in almost all seams the statistical evaluations and sem data show that some elements such as mg ti zr nb and th are generally affiliated with silicate minerals whereas elements like cu zn mo and pb are mainly associated with sulphide minerals the silicate minerals are generally detrital and the majority of carbonate minerals are of epigenetic origin the epigenetic carbonate and sulphide minerals suggest that circulated solutions within coal seams were mainly derived from ca2 rich solutions leached from overlying formations such as cretaceous aged zonguldak formations and from hydrothermal solutions that likely were derived from andesitic dykes within the basin the regional tectonic activities during coalification seem to have deformed coal bearing formations and therefore intra basinal solutions could have penetrated into the studied coal seams the epigenetic mineralisation also resulted in elemental enrichments and elevated ash yields total sulphur and volatile matter contents in some coal seams thus deformation during coalification controlled some coal quality parameters in the studied wells the coal facies diagrams suggest that palaeomires mostly accumulated under limno telmatic conditions whereas a telmatic environment was more common in palaeomires of the kozlu formation coal petrography suggests that peat forming vegetation and water tables in palaeomires were changeable during the late carboniferous

postdepositional history of the permian sequence in the denison trough eastern australia the diagenesis of permian siliciclastic sedimentary rocks of the denison trough is interpreted in terms of evolving pore water composition related to the burial history of the basin in the sandstones early precipitation of pyrite siderite and grain rimming illite smectite was followed by development of quartz overgrowths that incorporated silica released by pressure solution recrystallization of lithics and smectite illite reaction later as the sequence reached maximum burial during the late triassic strongly 18 o depleted siderite and ankerite which incorporated iron and magnesium liberated by leaching of detrital mafic minerals and continuing smectite illite reaction precipitated from connate meteoric pore water expelled upward from the underlying overpre sured continental reids dome beds this implies the existence of significant cross formational pore water flow prior to and during attainment of maximum burial regional late triassic to earliest jurassic compression resulted in major uplift and exposure of the permian sequence attendant strata concordant invasion of meteoric water led to labile grain and ferroan carbonate dissolution and to the formation of strongly 18 o depleted kaolinite and a second generation of quartz overgrowths later postdepositional events which occurred during a second cycle of burial and uplift include the precipitation of 18 o depleted calcite and dawsonite and hydrocarbon entrapment

organic matter characterization in mixed hydrocarbon producing areas within the duvernay formation western canada sedimentary basin alberta this paper characterizes organic matter in the mixed hydrocarbon oil dry gas oil condensate producing areas of the late devonian duvernay formation in alberta canada by high resolution rockeval data n 246 and petrography n 35 at three drillhole locations locations a and c distal location b proximal to leduc reef respectively total organic carbon toc ranges from 0 15 622 wt at location a 0 43 820 wt at location b and 1 84 5 23 wt at location c with an overall median value of 3 42 wt s2 values range from 0 20 7 42 mg hc g of rock at location a 022 4 23 mg hc g of rock at location b and 1 68 5 04 mg hc g of rock at location c these results for samples from locations a b and c indicate that kerogen is type i to type ii the hydrogen index hi of these rocks is significantly lower 160 mg hc g toc than that of traditional oil producing source rocks of this age similar to 400 700 mg hc g toc at locations a and c t max lies within the oil window with a mean value of 459 degrees c at location b t max varies greatly between 434 and 488 degrees c between the oil and gas window with no observable association with sample depth vitrinite reflectance of samples ranges from 0 99 1 32 t max values do not correlate with vitrinite reflectance of the samples r 2 0 04 nor with depth r 2 0 4 suggesting that t max is not a reliable indicator of thermal maturity in this system low toc s2 high mineral carbon is associated with intervals of intergrown sparry calcite and pyrite in petrographic samples at location b organic matter within the duvernay formation was characterized as almost entirely solid bitumens with very minor inertinite 1 by volume the rockeval and petrographic observations suggest that secondary diagenetic effects are the cause for the mixed hydrocarbon signature rather than any spatial variation in depositional environment or thermal maturation regimes c 2016 elsevier b v all rights reserved

the relationship between leaf physiognomy and climate based on a large modern dataset implications for palaeoclimate reconstructions in china abstract in this paper correlation between modern leaf physiognomy and climate in china are examined to optimize the use of leaf characters as a palaeoclimate proxy a large dataset was compiled recording the distribution of leaf physiognomic characters among 3166 native dicot trees species across 732 calibration grids on a county level grids span a range of ecological environments tropical rainforests to alpine shrubs across humid areas thirteen climatic parameters were included for each grid and 22 leaf physiognomic characters were scored for each tree species the correlation between leaf physiognomic characters and climatic parameters were calculated based on single linear regressions slr and multiple linear regressions mlr results indicate clear spatial distribution patterns linked to latitude exist for all leaf characters with temperature coldest month mean temperature cmmt and precipitation growing season precipitation gsp being the main climate controls moreover because leaf characters are more closely correlated with precipitation during the three wettest consecutive months p3wet rather than with precipitation during the three driest consecutive months p3dry seasonal variations in rainfall associated with the asian monsoon might especially influence leaf physiognomic characters closer correlations between leaf physiognomy and climate are seen using mlr compared with slr therefore mean annual temperature mat and mean annual precipitation map based on mlr equations provide the most promising basis for palaeoclimate reconstructions in china

dinosaur tracks at the nemegt locality paleobiological and paleoenvironmental implications abstract the nemegt locality is one of the most famous dinosaur localities in mongolia ever since the site was discovered in 1946 it yields abundant dinosaur skeletons however little attention had been given to dinosaur footprints at the locality the only nemegt dinosaur footprint study focused on descriptions of the footprints gave only a few taxonomic implications and provided no comparison with other dinosaur tracksites this study reports newly recorded dinosaur footprints hadrosaurs sauropods and theropods at the nemegt locality during the nemegt educational expedition of 2016 a single footprint bearing horizon that extends several kilometres was examined within the nemegt formation to determine the ichno taxonomic assemblage of the nemegt dinosaurs a significant difference was identified between taxonomic compositions based on skeletal remains and ichno taxonomic compositions based on footprints although the vast majority of the skeletal elements collected in the area belong to theropods the footprints suggest that the nemegt locality was dominated by herbivorous dinosaurs this suggests that the previously inferred tarbosaurus dominant taxonomic composition at the nemegt locality is a result of a preservational bias the size distribution of the newly studied footprints suggest that the nemegt hadrosaurs had an adult dominant and multigenerational population structure comparisons with dinosaur tracksites at the cantwell alaska usa and tremp spain formations show that the population structure and body sizes of the nemegt hadrosaurs were similar to those of the high latitude cantwell hadrosaurs it suggests that the nemegt area was more open and had higher plant productivity than the tremp area

herd structure in late cretaceous polar dinosaurs a remarkable new dinosaur tracksite denali national park alaska usa the discovery of a new tracksite of mostly hadrosaurid dinosaur footprints made by a herd living in an ancient high latitude continental ecosystem provides insight into the herd structure and behavior of northern polar dinosaurs and perspective on populations of large bodied herbivores in an arctic greenhouse world this tracksite occurs in the upper cretaceous cantwell formation in the alaska range denali national park alaska united states and it is the largest tracksite known from this far north preservation of the tracksite is exceptional most tracks regardless of size contain skin impressions and they co occur with well preserved plant fossils and invertebrate trace fossils of terrestrial and aquatic insects statistical analyses of the tracks show that individuals of four different age classes of hadrosaurids lived together in a large social group our research results independently corroborate the growth curve for hadrosaurids proposed by paleohistologists that suggests that these dinosaurs experienced a period of rapid growth early in their life history

diagenetic history of eocene wilcox sandstones south central texas abstract sandstones and shales of the lower eocene wilcox group extend from outcrop to depths greater than 5 km where temperatures exceed 200 c eight authigenic minerals have been identified quartz kaolinite calcite ankerite and albitized plagioclase are volumetrically significant whereas chlorite illite albite overgrowths and dolomite are present only in trace amounts quartz kaolinite and ankerite cements are present over the entire depth range sampled 1528 to 4446 m calcite cement occurs only in sandstones shallower than 3300 m albitized plagioclase is the predominant feldspar in samples deeper than 2600 m whereas detrital potassium feldspar has been completely dissolved out of sandstones deeper than about 3200 m no systematic variations in the chemical composition of calcite with depth no zoning within calcite or ankerite and no compositional differences between pore filling and grain replacing calcite or ankerite were found calcite cements have 87 sr 86 sr ratios generally less than 0 708 whereas ankerite cements are significantly enriched in 87sr the oxygen isotopic composition of carbonate cement ranges between 9 and 14 pdb for calcite and between 8 and 12 for ankerite with no systematic variation with depth calculated 18o values for authigenic quartz and kaolinite range from 22 to 31 smow and from 14 to 17 respectively volumetrically important amounts of authigenic quartz and kaolinite precipitated during early burial before calcite cementation secondary porosity generation or smectite to illite transformation in encasing shales the isotopic composition of strontium in calcite cement shows most of it to be of eocene or older marine carbonate origin ankerite cementation followed the generation of secondary porosity and occurred after the products of organic maturation and shale diagenesis plagioclase albitization or potassium feldspar dissolution significantly affected the sandstone pore water system

terrestrial isotopic evidence for a middle maastrichtian warming event from the lower cantwell formation alaska abstract carbon stable isotope data 13c and new radiometric dates indicate that the non marine late cretaceous lower cantwell formation central alaska registers the middle maastrichtian event mme a global warming episode a stratigraphic section measured at the east fork of the toklat river in denali national park preserve includes a bentonite layer that we have dated to 69 5 0 7 ma using u pb isotope analysis of zircons the new depositional age confirms that dinosaur tracks from the lower cantwell formation are coeval with dinosaur bones from outcrops of the prince creek formation on alaska s north slope 13c data from fossil wood recovered from the lower cantwell formation records an 3 positive excursion correlative with positive excursions from terrestrial and marine sections in west texas usa and gubbio italy respectively the similarity between marine and terrestrial records suggests that this excursion is the result of a major perturbation in the global carbon cycle known as the middle maastrichtian event mme mean annual precipitation map estimates calculated from 13c data yield a range of 168 470 mm yr during the mme 353 1050 mm yr before and 475 1451 mm yr after the warming event the 13c record from the lower cantwell formation provides the first terrestrial high latitude evidence for the mme while map estimates for the coeval prince creek formation suggest that the arctic coast may have been more humid than southern interior alaska during the middle maastrichtian

terrestrial palynomorph biostratigraphy of the cypress hills wood mountain and turtle mountain areas upper cretaceous paleocene of western canada three cored test holes were drilled to study the stratigraphic interval spanning the cretaceous tertiary boundary one in the western cypress hills near elkwater alberta a second in the eastern portion of the wood mountain area near killdeer saskatchewan and a third on the western edge of turtle mountain near goodlands manitoba the terrestrial elements of the palynological assemblages are discussed the maastrichtian assemblages encompassed the scollardia trapaformis zone and two new subzones myrtipites scabratus aquilapollenites delicatus var collaris and porosipollis porosus aquilapollenites notabile within the wodehouseia spinata zone the paleocene zones encountered include the aquilapollenites reticulatus subzone of the w spinata zone the previously described wodehouseia fimbriata and momipites wyomingensis zones and the newly defined tricolporopollenites kruschii zone these provide a biostratigraphy for the cored intervals which can be related to polarity chrons the observations mad

depositional and compositional controls on sandstone diagenesis the tetori group middle jurassic early cretaceous central japan abstract the tetori group is a representative middle jurassic to lower cretaceous deposit in the northern central part of honshu japan the tetori group is divided into the kuzuryu itoshiro and akaiwa subgroups with decreasing age it consists mainly of a marine sequence in the lower part kuzuryu subgroup and non marine sequence in the upper part akaiwa subgroup with transitional sequence in the middle part itoshiro subgroup diagenesis of tetori group sandstones comprises compaction cementation and replacement early diagenetic events include mechanical compaction and pore filling cementation of calcite siderite dolomite and formation of kaolinite late diagenesis includes formation of quartz cement and albitization of feldspar and formation of illite chlorite calcite ankerite and pyrite among the diagenetic minerals carbonate forms the major cement in tetori group sandstones calcite of each subgroup is subdivided into two or three types based on cathodoluminescence tetori group sandstones of marine fresh water and mixed depositional environments are characterized by distinct chemical compositions of early diagenetic calcites late diagenesis seems to have been mainly influenced by detrital compositions of the sequence burial temperatures and partially hydrothermal processes especially late diagenetic carbonate and authigenic clay minerals seem to have formed mainly from ions released from clay mineral transformations in the adjacent shales based on the illite crystallinity ic the kuzuryu subgroup exhibits higher diagenetic grades than the overlying itoshiro and akaiwa subgroups indicating that the diagenesis of the tetori group was mainly affected by depth of burial

a review of anomalous rare earth elements and yttrium in coal abstract coal deposits have attracted much attention in recent years as promising alternative raw sources for rare earth elements and yttrium rey not only because the rey concentrations in many coals or coal ashes are equal to or higher than those found in conventional types of rey ores but also because of the world wide demand for rey in recent years has been greater than supply in addition to anomalies of enrichment or depletion of light medium and heavy rey in coal deposits normalized to upper continental crust post archean australian shale or north american shale composite anomalies of redox sensitive ce and eu and in some cases of non redox sensitive la gd and y could be used as geochemical indicators of the sediment source region sedimentary environment tectonic evolution and post depositional history of coal deposits factors controlling rey anomalies in coal deposits include the geochemistry of terrigenous source rocks ingress of hydrothermal fluids influence of marine environments percolating natural waters volcanic ashes and sedimentary environments of peat formation additionally the smoothness of a normalized rey distribution pattern provides a simple but reliable basis for testing the quality of rey chemical analyses for coal and other sedimentary rocks

petrographic and isotope constraints on the origin of authigenic carbonate minerals and the associated fluid evolution in late permian coal measures bowen basin queensland australia authigenic carbonate minerals are ubiquitous throughout the late permian coal measures of the bowen basin queensland australia in the northern bowen basin carbonates include the following assemblages siderite i delta o 18 smow 11 4 to 17 delta c 13 pdb 5 3 to 120 fe mg calcite ankerite siderite ii mineral association delta o 18 smow 7 2 to 10 20 delta c 13 pdb 10 9 to 1 80 for ankerite and a later calcite delta o 18 smow 5 9 to 14 60 delta c 13 pdb 11 4 to 4 40 in the southern bowen basin the carbonate phase consists only of calcite delta o 18 smow 12 5 to 14 80 delta c 13 pdb 19 4 to 0 80 where it occurs extensively throughout all stratigraphic levels siderite i occurs in mudrocks and sandstones and predates all other carbonate minerals this carbonate phase is interpreted to have formed as an early diagenetic mineral from meteoric waters under cold climate and reducing conditions fe mg calcite ankerite siderite il occur in sandstones as replacement of volcanic rock fragments clay minerals illite smectite chlorite and kaolinite postdate ca fe mg carbonates and precipitation of the later calcite is associated with clay mineral formation the ca fe mg carbonates and later calcite of the northern bowen basin are regarded as having formed as a result of hydrothermal activity during the latest triassic extensional tectonic event which affected this part of the basin rather than deep burial diagenesis during the middle to late triassic as previously reported this hypothesis is based on the timing relationships of the authigenic mineral phases and the low delta o 18 values of ankerite and calcite together with radiometric dating of illitic clays and recently published regional geological evidence following the precipitation of the ca fe mg carbonates from strongly o 18 depleted meteoric hydrothermal fluids continuing fluid circulation and water rock interaction resulted in dissolution of these carbonate phases as well as labile fragments of volcaniclastic rocks subsequently the later calcite and day minerals precipitated from relatively evolved o 18 enriched fluids the nearly uniform delta o 18 values of the southern bowen basin calcite have been attributed to very low water rock ratio in the system where the fluid isotropic composition was buffered by the delta o 18 values of rocks c 2000 elsevier science b v all rights reserved

diagenesis of upper carboniferous rocks in the ouachita foreland shelf in mid continent usa an overview of widespread effects of a variscan equivalent orogeny diagenesis of upper carboniferous foreland shelf rocks in southeastern kansas took place at temperatures as high as 100 150 c at a depth of less than 2 km high temperatures are the result of the long distance hundreds of kilometers advection of groundwater related to collisional orogeny in the ouachita tectonic belt to the south orogenic activity in the ouachita area was broadly late carboniferous equivalent to the variscan activity of europe mississippi valley type pb zn deposits and oil and gas fields in the us midcontinent and elsewhere are commonly attributed to regional groundwater flow resulting from such collisional events this paper describes the diagenesis and thermal effects in sandstone and limestone of upper carboniferous siliciclastic and limestone shale cyclothems the purported confining layer of a supposed regional aquifer diagenesis took place in early intermediate and late stages many intermediate and late stage events in the sandstones have equivalents in the limestones suggesting that the causes were regional the sandstone paragenesis includes siderite cement early stage quartz overgrowths intermediate stage dissolution of feldspar and carbonates followed by minor fe calcite pore filling kaolinite and sub poikilotopic ca ankerite late stage the limestone paragenesis includes calcite cement early stage megaquartz chalcedony and fe calcite spar intermediate stage and dissolution ca fe dolomite and kaolinite late stage the r m value of vitrinite shows a regional average of 0 6 0 7 rock eval t max suggests a comparable degree of organic maturity the t h of aqueous fluid inclusions in late stage ca fe mg carbonates ranges from 90 to 160 and t mice indicates very saline water 200000 ppm nacl equivalent 18o suggests that the water is of basinal origin local warm spots have higher r m t max and t h the results constrain numerical models of regional fluid migration which is widely viewed as an artesian flow from recharge areas in the ouachita belt across the foreland basin onto the foreland shelf area such models must account for heating effects that extend at least 500 km from the orogenic front and affect both supposed aquifer beds and the overlying supposed confining layer warm spots indicate either more rapid or more prolonged flow locally t h and t mice data show the highest temperatures coincided with high salinity fluids

rare earth element fractionation in authigenic illite smectite from late permian clastic rocks bowen basin australia implications for physico chemical environments of fluids during illitization ree analyses were performed on authigenic illitic clay minerals from late permian mudrocks sandstones and bentonites from the bowen basin australia the mixed layer illite smectite exhibit ree patterns with an obvious fractionation of the hree from the lree and mree which is an apparent function of degree of illitization reaction the highly illitic r greater than or equal to 3 illite smectite from the northern bowen basin show a depletion of lree relative to the less illitic r 0 and 1 clays in contrast an enrichment of hree for the illite rich clays relative to less illitic clays is evident for the southern bowen basin samples the north american shale composite normalized la lu sn ratios show negative correlations with the illite content in illite smectite and positive correlations with the delta 18 o values of the clays for both the northern and southern bowen basin samples these correlations indicate that the increasing depletion of lree in hydrothermal fluids is a function of increasing water rock ratios in the northern bowen basin good negative correlations between la lu sn ratios and illite content in illite smectite from the southern bowen basin suggest the involvement of fluids with higher alkalinity and higher ph in low water rock ratio conditions increasing hree enrichment with delta 18 o decrease indicates the effect of increasing temperature at low water rock ratios in the southern bowen basin results of the present study confirm the conclusions of some earlier studies suggesting that ree in illitic clay minerals are mobile and fractionated during illitization and that this fact should be considered in studies of sedimentary processes and in identifying provenance moreover our results show that ree systematic of illitic clay minerals can be applied as an useful technique to gain information about physico chemical conditions during thermal and fluid flow events in certain sedimentary basins c 2003 elsevier science b v all rights reserved

cleat mineralization of upper permian baralaba rangal coal measures bowen basin australia coals from the permo triassic bowen basin have been investigated using a variety of complementary analytical techniques face cleat minerals in the studied samples are dominated by authigenic clays notably pure illite or illite chlorite mixtures butt cleats and joints are dominated by carbonates mostly calcite with less abundant ferroan calcite ankerite and siderite k ar ages of cleat fill illites and one fracture illite smectite fill indicate three phases of illite formation during the triassic 1 an early phase with ages clustered around 244 ma ago 2 a second phase about 232 ma ago and 3 the latest phase about 219 ma ago thermal modelling of selected boreholes from the study area and other geological data indicate that the first phase of illitization occurred when the coal seams were about 1000m below the surface and at a temperature of between 70 and 80 c at a time when the basin was rapidly subsiding these early illites were stable and retained their 1m polytype even after being exposed to temperatures of 150 190 c during maximum burial in the southeastern bowen basin the second phase of illitization at 232 3 occurred at about the time of maximum burial the latest phase took place between 223 3 and 212 3 ma ago and occurred in a wider temperature range between 170 and 100 c during a rapid uplift in the late triassic the bowen basin area experienced a second cycle of subsidence that commenced in the early jurassic with the formation of the surat basin which overlies the bowen basin and forms part of the great artesian basin system regional uplift and erosion in middle cretaceous times terminated sediment accumulation in the surat basin during the second cycle of burial widespread carbonate mineralization in butt cleats and joints took place calcite fluid inclusions indicate that calcite was precipitated from meteoric water at about 80 c the widespread carbonate mineralization in butt cleats and the near absence of carbonates in the face cleats is here attributed to permeability anisotropy caused by a change in the direction of lateral compressive stress during jurassic cretaceous times relative to that during the triassic hunter bowen orogeny

modelling equable climates of the late cretaceous can new boundary conditions resolve data model discrepancies late cretaceous maastrichtian climate and vegetation is modelled using the hadcm3l fully coupled atmosphere ocean model and the triffid dynamic vegetation model we investigate data model inconsistencies in the high latitudes and continental interiors by exploring the sensitivity of modelled terrestrial climate to vegetation treatment changing atmospheric pco2 levels and the representation of arctic seaway connections we expand on previous work by using millennial scale gcm runs with dynamic vegetation to allow for improved representations of ocean heat transport and terrestrial boundary conditions incorporating realistic vegetation drives high latitude warming particularly during summer through reductions in surface albedo and induced atmosphere ocean feedbacks resulting regional warming can exceed 10 c as pco2 rises some regions cool as deciduous to evergreen change increases albedo incorporating enhanced arctic connectivity reconfigured ocean heat transport drives widespread terrestrial warming of 3 c and 5 c regionally applying sensitivities in combination significant palaeobotanical data model inconsistencies in the northern high latitudes and continental interiors remain further work is required to resolve climate and vegetation model deficiencies and improve the interpretation and geographic distribution of quantitative climate sensitive geological proxies

geochemical evolution of pore waters in the rotliegend early permian of northern germany abstract the distribution of early cements within permian rotliegend sandstones closely resembles cementation patterns within modern playa lake basins the isotopic compositions of eogenetic cements in the thick rotliegend sequence of germany show continental signatures typical of minerals precipitated in such an environment carbon sulphur and strontium isotopic ratios of many rotliegend cements which formed during burial suggest formation from a mixture of rotliegend fluids and waters from the overlying zechstein evaporites a two component mixing model for the evolution of rotliegend pore waters indicates that the isotopic signatures in these cements may result from the introduction of only minor amounts of zechstein fluid

macroflora paleogeography and paleoecology of the upper cretaceous turonian santonian saanich member of the comox formation saanich peninsula british columbia canada morphotypes of plant macrofossil assemblages of the basal unit of the upper cretaceous turonian santonian comox formation nanaimo group vancouver island were investigated to provide insight into the character of the macroflora environment of deposition and paleogeography of vancouver island three floristic assemblages were documented one dominated by angiosperm morphotypes such as platanus menispermites and zizyphus like leaves another dominated by gymnosperm morphotypes such as those synonymous with glyptostrobus comoxensis bell and pseudoctenis latipennis heer seward and a third assemblage transitional between the previous two these assemblages suggest the saanich member was likely deposited in a barrier island estuarine floodplain complex with fluvial sedimentary input the macrofloral assemblage also includes many endemic taxa suggesting a barrier to floral migration between the paleocontinent and the vancouver island precursor during the upper cretaceous which supports the existe