geochemistry and petrology of palaeocene coals from spitsbergen part 1 oil potential and depositional environment abundant oil prone coal type iii kerogen deposits are preserved within the high latitude middle palaeocene todalen member of the central tertiary basin spitsbergen island norwegian arctic the coals svea longyear svarteper and askeladden seams have been subjected to only minor previous geochemical characterisation focussing upon the longyear seam this paper characterises the present prospective and economic oil potential of the svalbard coals organic biomarker parameters fe s chemistry and coal maceral analysis are then applied to understand the provenance and environmental origins of this unusual source rock the upper todalen mbr coals longyear svarteper and askeladden seams have significantly more oil potential than the lower svea seams with estimated retortion yields of 170 190 kg tonne vs 24 kg tonne respectively the longyear seam exhibits relatively high hi values ca 300 400 mg g toc consistent with a hydrogen rich mixed type ii iii kerogen source greatest oil potential is shown to be favoured by formation within a fen environment with high bacterial degradation 100 g g toc hopanes marine influence 0 5 wt sulfur fe s 0 9 and the unique temperate high latitude palaeocene climate of svalbard leading to preservation of hydrogen rich organic matter via organo sulfur bond formation

slow release of fossil carbon during the palaeocene eocene thermal maximum a brief period of warming 55 9 myr ago has been attributed to the release of massive amounts of carbon geochemical and model data suggest the peak rate of carbon emission during this interval was relatively slow and significantly lower than present day levels of carbon emissions to the atmosphere

evolution of the central tertiary basin of spitsbergen towards a synthesis of sediment and plate tectonic history abstract the central tertiary basin of spitsbergen developed east of a strike slip boundary between the eurasian and greenland plates in response to the initiation of rifting and later seafloor spreading in the norwegian greenland sea using a new plate model for the opening of the north atlantic we attempt to relate the sediment history of the central tertiary basin to its plate tectonic framework and suggest a basin development in four phases the central tertiary basin was formed in the early paleocene during a right lateral strike slip phase after the plate boundary between greenland and svalbard had jumped eastward to the hornsund fault zone phase 1 the onset of seafloor spreading between greenland and eurasia and a drastic counterclockwise change in spreading direction between greenland and north america after chron 25 late paleocene induced compression dominated transpression between greenland and svalbard until chron 24 lower eocene phase 2 the first sedimentary evidence for tectonic uplift along the strike slip zone is found in a wedge shaped delta fan in the northwestern part of the basin strike slip dominated transpression prevailed from chron 24 to chron 21 lower middle eocene contemporaneous with successive basin narrowing and an eastward migration of the depocenter phase 3 after chron 21 lower middle eocene the relative motion between greenland and svalbard first changed to strike slip terminating the transpressional phase and then to transtension after chron 13 lower oligocene phase 4

organic matter composition and sulfate reduction intensity in oman margin sediments abstract petrographical and geochemical studies of neogene marine sediments from the oman sea leg 117 sites 720 724 726 and 730 show a close relationship between the nature and amount of the organic matter and the degree of degradation of organic matter by sulfate reduction i e pyritization petrographically three major pyritization types were observed 1 finely dispersed pyrite framboids in sediments from oman margin and indus fan enriched in autochthonous marine organic matter 2 infilling of pores by massive pyrite crystals in oman margin sediments with a low toc and a high microfossil content 3 pyrite mineralization of lignaceous fragments in organic depleted sediments from the indus fan leading to more massive pyrite geochemically we can define a sulfate reduction index sri as the percentage of initial organic carbon versus that of residual organic carbon finely laminated pliocene pleistocene sediments from the oman margin exclusively contain organic matter deriving from organic phytoplankton for which the quantity toc positively correlates with the geochemical quality hydrogen index we think that the occurrence of this residual organic matter is linked mainly to a high primary paleo productivity the intensity of sulfate reduction is constant for sediments with toc up to 2 and becomes more important when organic input decreases this degradation process can destroy up to 50 of the initial organic matter but is not sufficient to explain some of the encountered very low toc values it can be seen that sharp increases of certain plankton species with mineral skeletons are responsible for a pronounced degradation of organic matter due to increased sulfate reduction in that case the organic matter may be strongly degraded high sri although deposited in an oxygen depleted environment conversely miocene pliocene sediments contain an autochthonous organic matter that is typical of both low productivity and oxic processes their very low sulfate reduction index indicates that very little metabolizable organic matter was initially present

heat flux through sea ice in the western weddell sea convective and conductive transfer processes the heat flux through the snow and sea ice cover and at the ice ocean interface were calculated at five sites in the western weddell sea during autumn and early winter 1992 the ocean heat flux averaged 7 2 w m2 from late february to early june and average ice air heat flux in the second year floes depended on the depth of the snow cover and ranged from 9 to 17 0 8 w m2 in late february three of the five sites had an ice surface which was depressed below sea level resulting at two of the sites in a partially flooded snow cover and a slush layer at the snow ice interface as this slush layer froze to form snow ice the dense brine which was rejected flowed out through brine drainage channels and was replaced by lower salinity nutrient rich seawater from the ocean upper layer we estimate that about half of the second year ice in the region was covered with this slush layer early in the winter as the slush layer froze over a 2 to 3 week period the convection within the ice transported salt from the ice to the upper ocean and increased total heat flux through the overlying ice and snow cover on an area wide basis approximately 10 cm of snow ice growth occurred within second year pack ice primarily during a 2 to 3 week period in february and march this ice growth near the surface of the ice provides a salt flux to the upper ocean equivalent to 5 cm of ice growth despite the thick about 1 m ice cover in addition to the ice growth in the small area less than 5 open water regions

geochemical facies analysis of fine grained siliciclastics using th u zr rb and zr rb sr ratios abstract abundance of the trace elements zr rb sr th and u may provide insight into the sedimentological origin of fine grained siliciclastic sediments provided that the units are derived from similar source areas as demonstrated here with suites of the fine grained jurassic and cretaceous rocks from the barents sea and svalbard zr rb ratios can be interpreted to indicate grain size variations while zr rb sr values reflect variations in the siliciclastic versus carbonate contents the th u ratio can be applied as an indicator of the redox conditions in 3d plots such as presented here the interplay between these geochemical factors can be interpreted in terms of the sedimentological evolution of the depositional basin the geochemical facies analyses show that similar depositional conditions existed on the jurassic shelf in the two studied localities the succeeding prodeltaic cretaceous beds were generally coarser grained and deposited in ventilated depositional conditions

element and isotope geochemical investigations of the kupferschiefer in the vicinity of rote faule indicating copper mineralization sangerhausen basin g d r abstract based upon extensive data on the elemental and isotopic compositions of kupferschiefer of the sangerhausen basin and according to results of trace element and structural investigations of bitumen extracts trends of lateral and vertical distribution of various elements and genetic assertions are presented irregular positions of f v se au and u in the correlation diagram peculiarities of the lateral distribution of these elements abnormally high elemental concentrations in the rocks and in the bituminous extracts as well as alterations discovered in the composition of hydrocarbon groups and their structures support the idea of an influx of oxidizing metalrich waters moving through the rote faule from the rotliegendes basin into the kupferschiefer sediment isotope geochemical investigations carbon nitrogen and oxygen of organic carbonate and silicate fractions were carried out in order to characterize more precisely the conditions of sedimentation and the regime of diagenesis the contrary 13 c curves of pb zn facies and rote faule facies and the 13 c enrichment in the organic matter of rote faule can be explained by different redox conditions during sedimentation and or diagenesis furthermore the decreasing 18 o values of carbonates of the rote faule also suggest an influx of meteoric waters the results oppose a final syngenetic to early diagenetic fixation of the metal contents in kupferschiefer areas in the vicinity of rote faule the established model of influx of metalliferous fluids which arose from the rotliegendes is of local interest for element input and element redistribution

winter snow cover on sea ice in the weddell sea measurements of snow thickness temperature salinity density and stratigraphy acquired during the 1992 winter weddell gyre study are presented results indicate that the winter snow cover on sea ice in the weddell sea is extremely variable extreme fluctuations in antarctic synoptic conditions air temperature precipitation humidity and wind speed occur during the austral winter they result in unique modifications and additions to the snow layer during the aging process and act to stabilize an otherwise easily wind redistributed shallow snow cover and develop well packed drift features the latter occur even over relatively undeformed areas of sea ice and have a significant localized effect on the snow thickness distribution significant variability in snow grain size mean 2 73 3 12 mm and density 0 32 0 09 g cm 3 is observed as a result of cyclical switches between high and low temperature gradient metamorphism multiple icy layers indicate multiple thaw freeze events one such event occurred during a 3 day station during which the air temperature rose by 22 c in 12 hours to approximately 0 c this paper also examines mechanisms for flooding of the snow ice interface including snow loading even where the latter is not a factor the layer of snow immediately above the snow ice interface is commonly damp and saline 10 limitations in the data set are discussed and comparisons are drawn with other experiments

hydrogen index as reflecting intensity of sulphidic diagenesis in non bioturbated shaly sediments abstract based on 13 published porewater h 2 s and sulphate profiles the amount of h 2 s escaping from non bioturbated shales varies between some few to 45 of the amount of bacterially generated h 2 s this finding permits calculation of the original organic carbon toc or content of immature nonbioturbated shales using toc and sulphur content data in two immature non bioturbated sequences from hungary toarcian and oligocene the first order correlation between hi and toc toc or was found to be stronger than that between hi and toc indicating that sulphate reduction was the leading process both in decrease in toc content and degradation of kerogen source potential

burial of organic carbon and pyrite sulfur in sediments over phanerozoic time a new theory in present day marine sediments almost all of which are deposited in normal oxygenated seawater rates of burial of organic carbon c and pyrite sulfur s correlate positively and bear a constant ratio to one another c s 3 on a weight basis by contrast calculations based on the isotopic model of garrels and lerman 1981 indicate that at various times during the phanerozoic the worldwide burial ratio must have been considerably different than the present day value this ratio change is caused by the requirement that increases in the worldwide mass of organic carbon must be accompanied by equivalent decreases in the mass of sedimentary pyrite sulfur in order to maintain a roughly constant level of o2 in the atmosphere such apparently contradictory behavior can be explained if the locus of major organic carbon burial has shifted over time from normal marine environments as at present to non marine freshwater or to euxinic environments in the geologic past a shift to predominantly freshwater burial can help explain predicted high c s ratios in permo carboniferous sediments and a shift to euxinic environments can help explain predicted low c s ratios during the early paleozoic it is demonstrated that the three environments today exhibit distinguishably different average c s ratios

microtextures geochemistry and geochronology of authigenic xenotime constraining the cementation history of a palaeoproterozoic metasedimentary sequence an 26 m thick unit of phosphatic sandstone and black shale the phosphatic unit in the palaeoproterozoic mount barren group of south western australia contains abundant authigenic xenotime crystals showing well preserved diagenetic textures despite extensive regional deformation and thermal metamorphism the peak of which occurred at 1205 ma the phosphatic unit was preserved as a low strain envelope because of its pre compaction carbonate and phosphate cementation in situ u pb geochronology of xenotime reveals four discrete age populations at 1693 4 1645 3 1578 10 and 1481 21 ma when integrated with petrography the age data place a timeframe on i sediment deposition ii phosphogenesis iii diagenetic cement infilling iv diagenetic pyrite formation v secondary porosity generation vi hydrocarbon migration vii burial compaction and viii hydrothermal alteration up until peak thermal metamorphism xenotime growth at 1693 ma occurred prior to compaction whereas xenotime growth at 1645 ma occurred during burial xenotime growth at 1580 ma and at 1480 ma appears to be the far field record of thermotectonic events associated with intracontinental extension and magmatism recorded elsewhere in australia geochemical analysis integrated with geochronology shows a systematic increase in mree hree in xenotime crystals with decreasing age and with increasing stratigraphic depth coupled with a decrease in xenotime abundance and age with depth it suggests that i the main focus of porosity infilling was at the top of the phosphatic unit and progressed downwards over the 200 myr period of porosity infilling and ii the changes in xenotime ree chemistry may be due to an influx of mree from increasing amounts of dissolved apatite or changes with respect to ree solubility in the physiochemical nature of the fluids with burial depth

early diagenetic alteration of organic matter by sulfate reduction in quaternary sediments from the northeastern arabian sea abstract hemipelagic sediments from the northeastern arabian sea off pakistan were analyzed by geochemical and microscopical methods to study the importance of bacterial degradation processes on the quantity and composition of sedimentary organic matter om on the basis of elemental analysis of total organic carbon toc and total sulfur ts the decay of om by sulfate reducing bacteria were calculated concentrations of total iron reactive iron total nitrogen tn total phosphorus tp and hydrogen indices hi were used to assess organic matter reactivity and redox conditions stable sulfur isotopic compositions provided further information about pathway timing and mechanisms of sulfate reduction microscopical observations indicate that throughout the study area om is amorphous 75 95 in almost all samples with only a small contribution of terrigenous om bacterially mediated sulfate reduction leads to continuously decreasing toc ts ratios from 0 4 m to a burial depth of 2 3 m at this depth the anaerobic oxidation of particulate organic matter ceases sulfate reduction in this narrow interval accounts for the decay of up to 70 of the om which has primarily entered the anoxic domain during the bacterially mediated diagenesis preferential consumption of nitrogen and phosphorus containing organic compounds can be observed and quantified the regeneration of up to 60 of tn and more than 50 of tp can lead to a feedback of nutrients to the seawater this recycling process may contribute to the high productivity in the northeastern arabian sea

polynya dynamics a review of observations and modeling 1 polynyas are nonlinear shaped openings within the ice cover ranging in size from 10 to 105 km2 polynyas play an important climatic role first winter polynyas tend to warm the atmosphere thus affecting atmospheric mesoscale motions second ocean surface cooling and brine rejection during sea ice growth in polynyas lead to vertical mixing and convection contributing to the transformation of intermediate and deep waters in the global ocean and the maintenance of the oceanic overturning circulation since 1990 there has been an upsurge in polynya observations and theoretical models for polynya formation and their impact on the biogeochemistry of the polar seas this article reviews polynya research carried out in the last 2 decades focusing on presenting a state of the art picture of the physical interactions between polynyas and the atmosphere sea ice ocean system observational and modeling studies the surface heat budget and water mass transformation within these features are addressed

geometry and facies of tertiary clinothems spitsbergen sandstone clinothems from the battfjellet formation palaeogene on spitsbergen are locally exceptionally well preserved along depositional dip parallel mountainsides the clinothems are more than 1 km wide and more than 100 m thick superposition of several sandstone clinothems separated by mudstones reflects repeated shoreline progradation and transgression deposition took place partly on post transgressional depositional shelves and partly by contributing seaward sloping wedges or clinothems to a ramp progradation shorelines dominated both by mouth bar and shoreface environments have been identified the clinothems are organized into an overall progradational architecture with a geometry having features in common with progradational seismic facies

a modern vs permian black shale the hydrography primary productivity and water column chemistry of deposition the sediment currently accumulating in the cariaco basin on the continental shelf of venezuela has an elevated organic carbon content of approximately 5 is accumulating under o2 depleted bottom water conditions so42 reduction is composed dominantly of foraminiferal calcite diatomaceous silica clay and silt and is dark greenish gray in color upon lithification it will become a black shale recent studies have established the hydrography of the basin and the level of primary productivity and bottom water redox conditions these properties are used to model accumulation rates of cd cr cu mo ni v and zn on the seafloor the model rates agree closely with measured rates for the uppermost surface sediment the model is applied to the meade peak phosphatic shale member of the phosphoria formation a phosphate deposit of permian age in the northwest united states it too has all of the requisite properties of a black shale although the deposit is a world class phosphorite it is composed mostly of phosphatic mudstone and siltstone chert limestone and dolomite it has organic carbon concentrations of up to 15 is strongly enriched in several trace elements above a terrigenous contribution and is black the trace element accumulation defines a mean primary productivity in the photic zone of the phosphoria basin as moderate at 500 g m 2 year 1 organic carbon comparable to primary productivity in the cariaco basin the source of nutrient enriched water that was imported into the phosphoria basin upwelled into the photic zone and supported primary productivity was an o2 minimum zone of the open ocean the depth range over which the water was imported would have been between approximately 100 and 600 m the mean residence time of bottom water in the basin was approximately 4 years vs 100 years in the cariaco basin the bottom water was o2 depleted but it was denitrifying or no3 reducing rather than so42 reducing

organic geochemistry of the lower miocene oberdorf lignite styrian basin austria its relation to petrography palynology and the palaeoenvironment abstract in the oberdorf trough at the northwestern margin of the styrian basin austria an up to 36 m thick lower miocene ottnangian lignite seam occurs within the fluvial koflach voitsberg formation previous results indicate that the lignite originated in a topogenous mire within a wet forest swamp palaeoenvironment differences in soluble organic matter som yield of borehole samples from the lignite seam are related to free lipids present in plant waxes or resins and the presence of thermally labile polymers indicated by the contents of liptinite macerals i e resinite suberinite and liptodetrinite the n alkane distribution patterns are dominated by high molecular weight lipids with marked odd over even predominance originating from plant waxes a contribution of algae to the even numbered short chain lipids observed in considerable amounts in the footwall sediments is proposed terpenoid biomarkers characteristic for conifers and angiosperms were detected consistent with palynomorphic spectra which are dominated by forest swamp pollen taxodiaceae cupressaceae and pollen from plants living in a mixed mesophytic forest excellent relationships between higher plant biomarker composition and palynologic data indicate that the organic geochemical results reflect the varying inputs of coniferales vs angiosperms the data further imply that cuparene may be used for taxonomical differentiation of coniferales families organic geochemical data provide evidence that the content of land plant derived biomarkers is controlled by the input of resin rich conifers concentrations of hopanoids dominated by hop 17 21 ene generally increase towards the top of the lignite a section characterised by high extents of aromatisation of triterpenoid biomarkers the results suggest that the aromatisation of angiosperm derived biomarkers may be governed by the activity of anaerobic rather than by aerobic bacteria however changes in the depositional environment and palynologic facies during peat formation probably influenced the origin and fate of angiosperm derived triterpenoids the results indicate how biomarker composition may contribute to the evaluation of environmental changes cross correlations of organic geochemical parameters with palynological data and petrography based facies indicators will provide further insights in the peat forming vegetation and biogeochemical activities in the mire

sea level and salinity fluctuations during the paleocene eocene thermal maximum in arctic spitsbergen palaeoenvironmental manifestations of the palaeocene eocene thermal maximum petm 56 ma are relatively well documented in low to mid latitude settings and at high southern latitudes but no documented high northern latitude sites record the entire hyperthermal event we present high resolution multi proxy records from a petm succession on spitsbergen in the high arctic palaeolatitude 75 n by comparing our results with those from integrated ocean drilling program site 302 4a we document regional palaeoenvironmental variations in the expression of the petm with evidence for major differences in basin margin vegetation and water column oxygen depletion sedimentological palynological and geochemical data demonstrate a pre petm sea level rise in spitsbergen before the delta13ctoc excursion which culminated in maximum flooding during the peak of the event the appearance of the dinoflagellate cyst apectodinium before the onset of the carbon isotope excursion cie corroborates environmental change in the arctic had begun prior to the cie sedimentological and palynological evidence indicate that elevated terrestrial runoff resulted in water column stratification providing further evidence for an intensification of the hydrological cycle during the petm

18o concentrations in sea ice of the weddell sea antarctica we present data on ice texture salinity and delta o 18 obtained from identical sections of ice cores during the winter weddell sea project 1986 on rv polarstern from july through august 1986 in the longitude range between 5 degrees w and 7 degrees e we find no uniquely definable relationship between delta o 18 values and ice texture in a particular section however most of the snow ice as well as some sections of frazil ice ar found to have negative delta o 18 concentrations this is due to varying degrees of admixtures of meteoric ice snow and sea water during formation of snow ice in contrast to common assumptions our results seem to indicate that a snow cover contributes positively to sea ice growth rather than slowing down the overall growth rate based on a simple model we have estimated the contributions of meteoric ice mean of 3 3 and the combined meteoric ice sea water fraction a minimum of 7 6 to the total ice thickness for the majority of the sampled floes although this is only a moderate contribution to the overall mass balance in the absence of congelation growth it nevertheless enhances ice growth in general this hypothesis is dependently supported by our snow and ice thickness data wadhams and others 1987 which demonstrate that the depression of the snow ice interface below the water line i e a negative freeboard and the formation of snow ice is a common occurrence in the weddell sea therefore we hypothesize that the major part of the observed apparent increase in ice thickness between our inbound and outbound tracks of wwsp 86 may not be derived from regular thermodynamically driven congelation growth but rather from the snow ice component in floes of the weddell sea

carbon sulfur plots to show diagenetic and epigenetic sulfidation in sediments abstract organic carbon vs sulfide sulfur plots are now being used regularly by many geochemists to help understand recent and ancient depositional environments and diagenetic processes usually these plots are useful to recognize nonmarine vs marine environments or oxic vs anoxic vs euxinic depositional environments however c vs s plots can also indicate diagenetic and epigenetic events that produce excess sulfide four new examples are presented and discussed

a convective model for the weddell polynya abstract mechanisms are considered which may induct the large over 105 km2 area of open water or polynya which frequently occurs within the weddell sea winter sea ice we propose that when surface cooling and ice formation decrease the temperature and increase the salinity of the surface water the latter by salt rejection during ice formation in a preconditioned area static instability with intense vertical mixing can occur the upwelled warm salty deep water can then supply enough heat to melt the ice or prohibit its formation even in the middle of winter a simple two level model is derived to test this theory and is found to agree well with observations the process is found to be irregular due to different times of ice onset from one year to the next and to a lesser extent from variations in surface heating and cooling further it is shown that unless the freshwater input exactly balances the increased salinity from the overturn each year the system will either gain or lose salt yearly an

geochemical characterization of the depositional environment of paleocene and eocene sediments of the tertiary central basin of svalbard abstract the tertiary central basin ctb of svalbard has been studied extensively in the past because it contains sediments from the paleocene eocene thermal maximum petm previous studies have found that a negative carbon isotopic extrusion cie is presents without showing elevated concentration of organic carbon in this study we extend the record of the ctb with a comprehensive inorganic and organic geochemical data set based on the sediments encountered in the research well bh 10 2008 comprising almost 1100 m of cored sediments major and trace elements analyses in combination with mineralogical carbon isotopic total organic carbon and total sulphur measurements were used to reconstruct the depositional environments of the lower paleocene basilika fm up to the eocene aspelintoppen fm several depositional environments have been suggested which are consistent with the sedimentological interpretation of the respective well section back calculation of the initial organic carbon concentration shows that bacterial sulphate reduction had a major impact on the persevered organic carbon inventory of the lower basilika fm and of the paleocene eocene transition section based on organic carbon loss introduced by bacterial decay as well as measured isotopic composition we estimate an initial isotopic composition of the evaluated sediments which helps to elucidate on the fate of labile organic matter and explains the unusually low organic carbon inventory of the paleocene eocene transition sediments

organic matter production and preservation and evolution of anoxia in the holocene black sea dating of sediments collected in gravity cores during leg 1 of the 1988 r v knorr expedition to the black sea suggests that the onset of water column anoxia at 7 5 ka was virtually synchronous across the basin over a depth range of 200 2250 m a finely laminated organic carbon oc rich sapropel unit ii was produced as a result of this anoxia the trigger for increased oc production and development of anoxia was the spillover of saline waters through the bosporus that probably began at 9 0 ka and peaked between 7 0 and 5 5 ka this spillover enhanced vertical mixing and nutrient cycling and caused a short term 2 3 kyr burst in surface water productivity during the early part of unit ii deposition continued incursion of saline waters enhanced vertical stability and inhibited mixing of nutrients into surface waters thus limiting primary production and decreasing the oc flux to sediments beginning 5 5 ka concentration accumulation rate and degree of preservation of organic matter all decreased in the upper part of unit ii as a result of decreasing productivity but anoxia persisted throughout most of the water column the end of unit ii sapropel deposition was synchronous across the black sea as the result of the first blooms of the coccolith emiliania huxleyi which presumably marked an increase in surface water salinity above 11 and the beginning of unit i deposition the high coccolith carbonate fluxes that occurred during deposition of unit i diluted the oc concentration in the sediments but oc accumulation rates are about the same as those in upper part of unit ii

chlorite thermometry in the witwatersrand basin constraints on the paleoproterozoic geotherm in the kaapvaal craton south africa a series of post depositional alteration events can be distinguished in the late archean witwatersrand basin they range from thrust controlled metamorphism during pre transvaal crustal thickening burial metamorphism and hydrothermal infiltration during crustal thinning and associated deposition of the 2 6 2 1 ga transvaal supergroup sediments thermal metamorphism related to the 2 06 ga bushveld igneous complex and hydrothermal alteration as a consequence of the 2 023 ga vredefort impact event the relative importance of these events varies locally with different events responsible for the maximum temperatures achieved in different parts of the basin the pre transvaal metamorphism affected the northern margin of the basin whereas the syn bushveld thermal metamorphism is particularly pronounced in the lower parts of the witwatersrand supergroup chlorite geothermometry in conjunction with fluid inclusion microthermometry and the thermodynamic modeling of equilibrium mineral assemblages was applied

anoxia and high primary production in the paleogene central arctic ocean first detailed records from lomonosov ridge 1 except for a few discontinuous fragments of the late cretaceous early cenozoic climate history and depositional environment the paleoenvironmental evolution of the pre neogene central arctic ocean was virtually unknown prior to the iodp expedition 302 arctic ocean coring expedition acex drilling campaign on lomonosov ridge in 2004 here we present detailed organic carbon oc records from the entire ca 200 m thick paleogene oc rich section of the acex drill sites these records indicate euxinic black sea type conditions favorable for the preservation of labile aquatic marine algae type oc occur throughout the upper part of the early eocene and the middle eocene explained by salinity stratification due to freshwater discharge the superimposed short term milankovitch type variability in amount and composition of oc is related to changes in primary production and terrigenous input prominent early eocene events of algae type oc preservation coincide with global 13c events such as the petm and elmo events the elmo 13c event has been identified in the arctic ocean for the first time

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

enhanced coastal paleoproductivity and nutrient supply in upper egypt during the paleocene eocene thermal maximum petm mineralogical and geochemical evidence we have analyzed the geochemistry and mineralogy of the five characteristic beds that constitute the dababiya quarry member dqm recovered from the dababiya quarry core located near the global stratotype section and point gssp for the base of the eocene well developed in upper egypt these beds are known to record the isotopic and biotic signatures of the paleocene eocene thermal maximum petm we have extracted the mineral phases from these beds representing a total thickness of 2 35 m and compared them with those of the encasing shales through qualitative and semi quantitative sem analysis using edx technology total organic carbon was determined using the titrimetric method major and trace elements were analyzed using an inductively coupled plasma optical emission spectrometer and enrichment factors were established relative to al content we discuss the significance of our data with regard to basaltic volcanism and cometary impact for neither of which we find support in agreement with other studies our data indicate very high biological productivity during the deposition of the dqm this may be related to upwelling and or increased nutrient supply the latter because of an enhanced hydrologic cycle c 2011 elsevier b v all rights reserved

geochemical record of holocene to recent sedimentation on the western indus continental shelf arabian sea 1 we present a multiproxy geochemical analysis of two cores recovered from the indus shelf spanning the early holocene to recent 14 ka indus 23 is located close to the modern indus river while indus 10 is positioned 100 km further west the holocene transgression at indus 10 was over a surface that was strongly weathered during the last glacial sea level lowstand lower holocene sediments at indus 10 have higherendvalues compared to those at the river mouth indicating some sediment supply from the makran coast either during the deposition or via reworking of older sediments outcropping on the shelf sediment transport from makran occurred during transgressive intervals when sea level crossed the mid shelf the sediment flux from non indus sources to indus 10 peaked between 11 ka and 8 ka a hiatus at indus 23 from 8 ka until 1 3 ka indicates non deposition or erosion of existing indus shelf sequences higherendvalues seen on the shelf compared to the delta imply reworking of older delta sediments in building holocene clinoforms chemical index of alteration cia mg al and sr isotopes are all affected by erosion of detrital carbonate which reduced through the holocene k al data suggest that silicate weathering peaked ca 4 6 ka and was higher at indus 10 compared to indus 23 fine grained sediments that make up the shelf have geochemical signatures that are different from the coarser grained bulk sediments measured in the delta plain the indus shelf data highlight the complexity of reconstructing records of continental erosion and provenance in marine settings

preservation of elemental and isotopic source identification of sedimentary organic matter the amount and type of organic matter in the sediments of lakes and oceans contribute to their paleoenvironmental and paleoclimatological records only a small fraction of the initial aquatic organic matter survives destruction and alteration during sinking and sedimentation selective degradation modifies the character of the surviving small fraction of organic matter which becomes incorporated in bottom sediments organic matter alterations can continue to sub bottom depths of hundreds of meters corresponding to millions of years source and paleoenvironmental information nonetheless remains preserved in the molecular elemental and isotopic compositions of organic matter c n and 13c values of total organic matter in particular appear to retain paleoenvironmental information for multi myr time periods

delta influenced foraminiferal facies and sequence stratigraphy of paleocene deposits in spitsbergen abstract the paleocene firkanten formation of the central basin of spitsbergen is a succession of terrigenous clastic sediments interpreted as a major depositional sequence formed in deltaic coastal plain delta front and prodelta environments the present study combines diagnostic features of foraminiferal facies with sedimentary data to elucidate this sequence stratigraphic development deposition was initiated by an early paleocene transgression which led to the deposition of a delta plain to coastal marine sediment package forming the low stand and transgressive systems tracts these includes coal swamp lacustrine lagoonal and barrier deposits the lagoonal shales are characterised by an agglutinated foraminiferal assemblage of extremely low diversity indicative of hyposaline conditions shoreface sandstones overlying the lagoonal strata are interpreted as sand barriers reworked by the advancing transgression these sandstones are succeeded by a package of prodelta silty shales which in the lower part includes the maximum transgressive interval the foraminiferal assemblage of the prodelta shales is also agglutinated but reveals increased diversities suggesting open marine conditions the prodelta shales and overlying delta front sandtones form a succession of coarsening upwards parasequences of deltaic progradation representing the regressive systems tract the entirely agglutinated low diversity nature of the foraminiferal assemblages is in part attributable to the deltaic impact the restricted character of the faunas is additionally accentuated by the effects of the paleogene boreal province

the ice thickness distribution across the atlantic sector of the antarctic ocean in midwinter during the first leg of the winter weddell sea project antarktis v 2 cruise of f s polarstern the entire width of the antarctic sea ice zone was traversed in the vicinity of 0 longitude in the period july 18 to september 10 1986 ice thicknesses were measured by direct drilling and by helicopter profiling using an exstar 100 mhz impulse radar system in addition aerial photography of the ice cover was done from 100 to 2000 m altitude using a 70 mm aerial camera mounted in the helicopter the results of the point measurements drilling are reported in this paper together with an indication of how the radar and photography data will be used to extend them so as to yield area averaged ice thickness distributions it was found that the main ice type across the entire width of the ice cover was consolidated pancake ice occurring in vast floes this formed out of a 250 km wide band at the advancing ice edge which comprised a concentrated field of individual pancakes in a matrix of frazil ice preferred thicknesses of undeformed floes were 40 60 cm of ice covered with 5 15 cm of snow the individual pancakes attained almost all of this thickness before consolidation subsequent congelation growth was slow estimated at 0 4 cm d 1 the floes contained much small scale roughness on the upper and lower surfaces due to rafting of pancakes at the time of consolidation but pressure ridging was modest except in the far south a few very thick 8 11 m multiyear floes were observed embedded in the pack at latitudes beyond 66 s

geochemistry of recent toc rich sediments from the gulf of california and the black sea major and minor elements incl ag as ba cd co cr cu mn mo ni pb sr v zn have been determined in recent sediments from the gulf of california upwelling area and black sea sapropels in order to reinterpret their chemical composition in view of reliable seawater and plankton data the chemistry of the gulf of california sediments reflects regeneration processes which occur in the water column i e only a small fraction 10 of elements like cd which in seawater are coupled to the labile nutrients c n p is buried in the sedimentary column in contrast elements like the more resistant nutrients si undergo a deeper regeneration cycle ba several trace metals which are present in comparatively higher concentrations in seawater as mo u v and at the same time are reactive under reducing conditions and or are able to form stable sulfides are fixed in the sediments during early diagenesis the early diagenetic behavior of ba is closely related to bacterial sulfate reduction the formation of barite concretions is discussed anoxic conditions in the water column act as ideal traps for a number of redox sensitive and or stable sulfide forming elements a simple trace metal balance calculation shows that the chemical composition of black sea sapropels is controlled by fluvial and mediterranean seawater element input and the accumulation rate of terrigenous detrital material

degree of pyritization of iron as a paleoenvironmental indicator of bottom water oxygenation abstract a new method is presented for recognizing the degree of bottom water oxygenation in organic carbon bearing rock the method uses the parameter degree of pyritization dop which is the ratio of pyritic fe to pyritic fe acid soluble fe sediments with ages ranging from devonian to cretaceous have been classified on paleoecological and sedimentological criteria as having been deposited in aerobic conditions deposited in fully oxygenated bottom waters restricted marine conditions deposited in waters with low oxygen concentrations or inhospitable bottom conditions where little or no oxygen is present and h2s may be continually or intermittently present aerobic dop

crystal structure stable isotopes δ18o and development of sea ice in the ross amundsen and bellingshausen seas antarctica the crystal structure and oxygen isotopic composition of ice cores obtained from floes at the end of summer in the eastern ross sea the amundsen sea and the western bellingshausen sea were investigated to determine the ice growth processes and conditions that contribute to sea ice development in the eastern pacific sector of the southern ocean the isotope data indicate that a moderate amount of snow contributes to the development of the sea ice however even the combined use of isotopes and crystal structure analysis does not unambiguously explain the means by which all of the snow is entrained in the ice nevertheless it seems clear that much of the snow is contained in granular snow ice that results from seawater flooding of floes and the base of the snow cover the snow cover in the ross amundsen region was as much as 2 m deep and supported by 7 to 8 m thick floes primarily composed of frazil ice in the bellingshausen region the snow cover and the floes were thinner than in the ross amundsen region the bellingshausen cores were composed primarily of multiple layers of frazil and congelation ice in addition in both regions there were numerous tipped or inclined blocks of congelation ice and layers of rafted nilas in the cores the data indicate that the sea ice develops by multiple mechanisms in a turbulent environment

basin internal derivation of hydrocarbons in the witwatersrand basin south africa evidence from bulk and molecular δ13c data abstract gold in the quartz pebble conglomerates of the late archean witwatersrand basin south africa is often intimately associated with carbonaceous matter of organic biogenic origin which occurs in the form of stratiform carbon seams and paragenetically late bitumen nodules both carbon forms are believed to be formed by solidification of migrating hydrocarbons this paper presents bulk and molecular chemical and stable carbon isotope data for the carbonaceous matter all of which are used to provide a clue to the source of the hydrocarbons these data are compared with those from intra basinal shales and overlying dolostone of the transvaal supergroup the 13c values of the extracts from the witwatersrand carbonaceous material show small differences up to 2 4 compared to the associated insoluble organic matter this suggests that the auriferous rocks were stained by mobile hydrocarbons produced by thermal and oxidative alteration of indigenous bitumens a contribution from hydrocarbons derived from intra basinal witwatersrand shales cannot be excluded individual aliphatic hydrocarbons of the various carbonaceous materials were subjected to compound specific isotope analysis using on line gas chromatography combustion stable isotope ratio mass spectrometry gc c irms the limited variability of the molecular parameters and uniform 13c values of individual n alkanes 31 1 1 7 and isoprenoids 30 7 1 1 in the witwatersrand samples exclude the mixing of oils from different sources carbonaceous matter in the dolostones shows distinctly different bulk and molecular isotope characteristics and thus cannot have been the source of the hydrocarbons in the witwatersrand deposits all the various forms of witwatersrand carbon appear indigenous to the witwatersrand basin and the differences between them are explained by variable in general probably short centimeter to meter scale hydrocarbon migration during diagenesis and subsequent hydrothermal infiltration

winter sea ice properties in marguerite bay antarctica abstract during the winter 2001 and 2002 cruises of the so globec experiment we investigated the morphological properties growth processes and internal permeability of sea ice in the marguerite bay area of the western antarctic peninsula there was considerable interannual variability in ice thickness with average values of 62 cm in 2001 and 102 cm in 2002 with medians of 43 and 68 cm respectively snow depth averaged 16 cm in 2001 and 21 cm in 2002 at 40 of the thickness holes in 2001 and 17 in 2002 a combination of deep snow and thin ice resulted in negative freeboard and the potential for surface flooding ice production was strongly influenced by the snow cover deep snow resulted in negative freeboard surface flooding and the formation of snow ice but also limited columnar ice growth on the bottom of the ice a stratigraphic analysis of ice thin sections showed that more than half of the ice sampled was granular and that virtually all of the upper 20 cm of the ice cover was granular stable isotope 18 o analysis of samples from 2001 indicated that snow ice formation at the surface contributed significantly to ice formation two thirds of the cores had some snow ice and 15 of the ice sampled in 2001 was snow ice for 95 of the ice sampled the combination of warm ice temperatures and large salinities resulted in brine volumes that were greater than the percolation threshold of 5 autonomous mass balance buoys indicated that the ice was above the percolation threshold throughout late winter and spring the exceeding of the percolation threshold allows continuous flooding to occur throughout the late winter spring period the wap sea ice therefore represents a warm end member of the sea ice covers of antarctica an expected consequence of the lengthy flooding condition at the snow ice interface is an earlier onset of an algal bloom in the flooded snow than elsewhere in antarctic sea ice

geochemical discrimination of clastic sedimentary rock sources abstract factors controlling the geochemistry of a clastic sedimentary rock can include 1 composition of source terrain 2 chemical weathering 3 hydraulic sorting 4 diagenesis 5 metamorphism and 6 hydrothermal alteration a linear solution inferring source terrain composition from geochemistry of the sediment is impossible in this multivariate system as several unknowns will commonly be present the use of graphical analysis of element pairs circumvents the problem chemically immobile elements will maintain invariant ratios during rock mass change caused by either addition or depletion of mobile elements this results in chemically immobile element scattergrams exhibiting linear trends along radians extending from the origin if the major mineral phases of the immobile elements have behaved in a hydrodynamically similar manner as chemically mobile element plots will produce a scatter of points this relationship can be used to test chemical immobility and similarity in hydrodynamic sorting history the constraint on analysis is that the source area must be compositionally uniform or the sediment well mixed prior to delivery to the basin a second technique using sio2 plots has also been developed to investigate element mobility and hydrodynamic behaviour of the mineral phases containing the elements sio2 immobile element plots result in a linear arrangement of points extending towards either 0 or 100 sio2 the 0 intercept position occurs for elements with major mineral phases concentrated in sand the 100 intercept for those concentrated in clays plotting chemically mobile elements produces different patterns and this can be used to gain information on alteration and sorting history elemental ratios for chemically immobile elements with similar hydrodynamic behaviour will be the same as those for the weighted average composition of the source material this provides a powerful tool for deducing source terrain from sediment geochemistry techniques outlined above were tested on archaean metasandstones from superior province canada immobile element ratio diagrams for nb al ti and zr al ti indicate that a calc alkaline extrusive intrusive suite lying to the north of the study area was the source and not five other volcanic suites in the region this conclusion agrees with previous clast lithology studies and accentuates the applicability of the geochemical techniques

roughness of weddell sea ice and estimates of the air ice drag coefficient the roughness of a sheet of sea ice encodes its deformational history and determines its aerodynamic coupling with the overlying air and underlying water here we report snow surface ice surface and ice underside roughness computed from 47 surface elevation profiles collected during a transect of the weddell sea the roughness for each surface parameterized as the standard deviation of the surface elevation segregates according to whether or not a floe has been deformed deformed ice has greater roughness than undeformed ice regardless of deformational history the underside roughness is almost always greater than the snow surface and ice surface roughnesses which are nearly equal roughness spectra for all three surfaces and for both deformed and undeformed ice roll off roughly as k 1 when the wavenumber k is between 0 1 and 3 rad m 1 the snow surface and underside spectra roll off somewhat faster than k 1 and the ice surface spectra roll off somewhat slower than k 1 both top and underside arctic ice roughness spectra on the other hand have been reported to roll off faster than k 2 we speculate that the excess spectral intensity at high wavenumbers in the antarctic ice surface spectra results from the small scale roughness that the ice sheet had on consolidation this excess high wavenumber spectral intensity persists in the ice surface spectra of second year ice evidently once formed the ice surface remains unchanged on the microscale until the entire ice sheet melts with a remote measurement of roughness we should be able to decide whether an ice floe is deformed or undeformed our spectral analysis hints that remote sensing may also be able to differentiate between first year and second year ice from the snow surface spectra we compute a roughness scale that parameterizes the air ice momentum coupling and lets us estimate the neutral stability drag coefficient referenced to a height of 10 m cdn10 typical cdn10 values are 1 1 1 4 10 3 over undeformed ice and 1 3 1 8 10 3 over deformed ice

a model study of differences of snow thinning on arctic and antarctic first year sea ice during spring and summer the one dimensional snow model sntherm is validated using field measurements of snow and superimposed ice thickness and surface energy fluxes these were performed during the spring to summer transition in svalbard and in the weddell sea antarctica both the seasonal snow thickness decrease and the formation of superimposed ice are well reproduced by the model during the three observation periods observed and modeled snow thickness differ only by 13 1 27 1 mm on average in regional studies the model is forced with atmospheric re analysis data european centre for medium range weather forecasts and applied to several meridional transects across the arctic and southern ocean these show fundamental regional differences in the onset duration and magnitude of snow thinning in summer in the central arctic snowmelt onset occurs within a narrow time range of 11 days and without significant regional differences in contrast the snow cover on antarctic sea ice begins to melt about 25 days earlier and the length of the antarctic snow thinning season increases with increasing latitude the importance of melting and evaporation for the modeled snow thickness decrease is very different in the two hemispheres the ratio of evaporated snow mass to melted snow mass per unit area is derived from the model and amounts to approximately 4 2 in the antarctic and only 0 75 in the arctic this agrees with observations and model results of the surface energy balance and illustrates the dominance of surface cooling by upward turbulent fluxes in the antarctic

using sea ice to measure vertical heat flux in the ocean results of an experiment performed at drifting ice station fram i in the arctic ocean northwest of spitzbergen during march may 1979 indicate that sensible heat flux from the ocean to the ice cover was less than 2 w m 2 the estimate is based on measurements of temperature gradient growth rate and salinity of young sea ice uncertainty in the magnitude of the heat flux results more from evidence of horizontal inhomogeneity in the growing ice sheet than from measurement errors

the paleocene eocene thermal maximum petm in svalbard clay mineral and geochemical signals abstract for the first time the paleocene eocene thermal maximum petm interval has been identified in drillcores and field outcrops from the paleogene central basin in svalbard based on mineralogical and geochemical information grumantbyen and frysjaodden formations a more than 300 m thick paleogene interval representing deltaic delta influenced marine shelf and deep water slope environments the petm has been recognized in the deepest and most distal deposits in the lower parts of the frysjaodden formation here this global event is displayed in clay mineralogical distributions as significantly increased kaolinite abundances reflecting a period with intensified chemical weathering in the land areas surrounding this paleogene basin the period was characterized by dominantly reducing sea floor conditions as seen in the th u distribution and the well developed parallel lamination in the pyrite rich shales all to be expected during an interval with increased temperature and precipitation

sea ice control of water isotope transport to antarctica and implications for ice core interpretation 1 sea ice in the southern ocean is important for antarctic climate and hydrology the dependence of water isotope abundance 18o and deuterium excess on the winter sea ice state is examined with the isotopic version of the melbourne university general circulation model reductions in the ice concentration provide warmer temperatures in winter and allow higher precipitation totals further south while the reverse occurs with increased ice extent the model shows clear demarcation between the changes in the isotopic conditions over the sea ice pack where local changes in surface exchange dominate and those of the continent interior which depend on the long ranged transport aloft while less sensitive to the forcing the interior response is influenced by changes in turbulent mixing over the ice pack and modification of the vertical transport associated with diabatic heating the interior deuterium excess response is more strongly affected by sea ice as it captures changes in temperature over the ice rather than just the final vapor mass traditional reconstruction of temperature from a single isotopic nuclide would give erroneous interpretation of change in the global mean temperature unless the sea ice changes in parallel instead the spatial structure of the sea ice response gives some hope for extracting past sea ice conditions from multicore analysis this study begins to explore the role of entropy production during transport such that the isotopic interpretation is more closely tied to the dynamics of the atmosphere than is expressed by idealized parcel analysis

geochemistry and petrology of palaeocene coals from spitzbergen part 2 maturity variations and implications for local and regional burial models the central tertiary basin is an uplifted part of the north barents shelf and should be an ideal location to understand the thermal history maximum burial depth and overburden thickness in this petroleum rich area efforts to quantify the thermal history of the region have been hampered by reports of hyper thermal conditions maturity gaps and maturity inversions in the tertiary vitrinite reflectance ro record this has been attributed to thermal insulation effects vitrinite reflectance due to bitumen impregnation and later tertiary volcanism through the use of ro organic maturity parameters 13c nmr and rock eval pyrolysis this study aims to explain the unusual maturity effects observed and the implications for burial models within single seams ro ranges from 0 5 to 0 78 with increasingly bimodal distribution up seam analysis of coal aromaticity and the results of rock eval analysis confirm that maturity gaps and inversions only occur where the vitrinite reflectance has been suppressed by high bitumen content 300 400 mg g coal samples with the lowest hydrogen index values 250 mg hc toc provide the most accurate estimates of the vitrinite reflectance results indicate maximum burial temperatures of 120 c in the basin centre and 100 c at the basin margins with a hyper thermal gradient of approximately 50 c km this gradient implies a total overburden of 2 km of which 1 km has been lost maximum burial depth and total erosional sediment load to the barents shelf are therefore at the lower end of current estimates

sea ice and snow cover characteristics during the winter spring transition in the bellingshausen sea an overview of simba 2007 abstract the sea ice mass balance in the antarctic simba experiment was conducted from the rvib n b palmer in september and october 2007 in the bellingshausen sea in an area recently experiencing considerable changes in both climate and sea ice cover snow and ice properties were observed at 3 short term stations and a 27 day drift station ice station belgica isb during the winter spring transition repeat measurements were performed on sea ice and snow cover at 5 isb sites each having different physical characteristics with mean ice snow thicknesses varying from 0 6 m 0 1 m to 2 3 m 0 7 m ice cores retrieved every five days from 2 sites and measured for physical biological and chemical properties three ice mass balance buoys imbs provided continuous records of snow and ice thickness and temperature meteorological conditions changed from warm fronts with high winds and precipitation followed by cold and calm periods through four cycles during isb the snow cover regulated temperature flux and controlled the physical regime in which sea ice morphology changed level thin ice areas had little snow accumulation and experienced greater thermal fluctuations resulting in brine salinity and volume changes and winter maximum thermodynamic growth of 0 6 m in this region flooding and snow ice formation occurred during cold spells in ice and snow of intermediate thickness in contrast little snow ice formed in flooded areas with thicker ice and snow cover instead nearly isothermal highly permeable ice persisted in spring short lived cold air episodes did not effectively penetrate the sea ice nor overcome the effect of ocean heat flux thus favoring net ice thinning from bottom melt over ice thickening from snow ice growth in all cases these warm ice conditions were consistent with regional remote sensing observations of earlier ice breakup and a shorter sea ice season more recently observed in the bellingshausen sea

vaalbara earth s oldest assembled continent a combined structural geochronological and palaeomagnetic test the only remaining areas of pristine 3 6 2 7 ga crust on earth are parts of the kaapvaal and pilbara cratons general similarities of their rock records especially of the overlying late archean sequences suggest that they were once part of a larger vaalbara supercontinent here we show that the present geochronological structural and palaeomagnetic data support such a vaalbara model at least as far back as 3 1 ga and possibly further back to 3 6 ga vaalbara fragmented prior to 2 1 ga and possibly as early as 2 7 ga suggesting supercontinent stability of at least 400 myr consistent with neoproterozoic and phanerozoic analogues

gold accumulation in the archaean witwatersrand basin south africa evidence from concentrically laminated pyrite abstract concentrically laminated pyrite is a relatively common although volumetrically minor component of auriferous conglomerates in the archaean ca 3 0 2 7 ga witwatersrand basin of south africa this type of pyrite contains high amounts several tens of ppm of au but the origin of the pyrite is debated and the timing of au deposition in these grains is not known in order to constrain the formation of pyrite we have studied concentrically laminated pyrite and other coexisting types of pyrite inclusion rich massive pyrite by analysing the contents and distribution of au and other trace elements by laser ablation icp ms the s and fe isotope composition by sims and the mineral inclusions by scanning electron microscope and laser raman spectroscopy trace element maps indicate that concentrically laminated pyrite is enriched in sb mn au ag tl cu mo mn and contains two types of gold finely dispersed au invisible gold with au ag 0 1 and likely of primary origin and au inclusions with au ag 10 of secondary origin the study of mineral inclusions revealed the presence of muscovite chlorite fine grained carbonaceous matter monazite ti oxides and quartz iron and multiple s isotopes suggest that concentrically laminated pyrite and inclusion rich pyrite were formed from two separate pools of s and fe with different isotope characteristics sulfur was derived from atmospheric s that had undergone mass independent isotope fractionation to form so 4 2 with negative 33 s that constituted concentrically laminated pyrite and elemental s with positive 33 s that formed inclusion rich pyrite iron pools were derived from partial oxidation of fe 2 so that concentrically laminated pyrite formed from a low 56 fe residual fe 2 average 0 2 and inclusion rich pyrite formed from a high 56 fe fe 3 pool average 2 7 biological activity may have been involved in the reduction of so 4 2 causing a wide spread of 34 s values 25 s reducing microorganisms as well as in the partial oxidation of fe 2 anaerobic photosynthetic fe reducers or photosynthetic o 2 producers and in the formation of pyrite from fe 3 dissimilatory fe reducers we propose that concurrent biogenically mediated pyrite formation and au trapping suggest that microbial activity was responsible for the accumulation of au and other trace elements e g sb mn ag tl cu mo mn which are commonly enriched in organic matter rich sediments