kennetcook thrust system late paleozoic transpression near the southern margin of the maritimes basin nova scotia a major zone of deformation affects early carboniferous rocks in the southern part of the maritimes basin of nova scotia close to the boundary between the avalon and meguma terranes of the appalachians field relationships at cheverie indicate thrusting of tournaisian horton group clastics over visean windsor group carbonates evaporites and clastics a relationship confirmed by the cheverie 01 well mapped relationships to the south indicate that a system of thrusts here termed the kennetcook thrust system climbs upsection to the southeast becoming a decollement within windsor group evaporites industry seismic profiles clearly show deformed windsor group and include fold and fault structures indicative of evaporite flow and solution collapse below the windsor group half grabens filled with horton group are clearly imaged offsets at graben related faults show that these structures were inverted during later shortening above the windsor group less deformed rocks of the pennsylvanian scotch vil

sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

maturation and bulk chemical properties of a suite of solid hydrocarbons abstract in this paper we present strong correlations of solid hydrocarbon reflectance shro to vitrinite reflectance vro and bulk chemical properties aromaticity tmax h c etc these correlations suggest that like kerogen in coals and sedimentary rocks solid hydrocarbons vary systematically during maturation as a consequence shro is especially useful as a maturity indicator in rocks lacking vitrinite such as pre devonian rocks and many organic rich marine rocks unlike other organic maturationv indicators the utility of solid hydrocarbons is not limited by botanical evolution but rather the generative potential of the petroleum system solid hydrocarbons also known as solid bitumen asphalt dead oil migrabitumen and pyrobitumen are genetically defined as solid phase accumulations of predominantly hydrocarbons produced by petroleum generation in source rocks they may occur over a range of concentrations in outcrop and well samples in all components of petroleum systems although accumulations of solid hydrocarbons from exhumed reservoirs are well reported the extent and utility of disseminated solid hydrocarbons in shales is less understood solid hydrocarbons are found in organic rich to very lean mature rocks as a residual product of generation disseminated solid hydrocarbons exhibit three optical forms anisotropic coked granular and relatively uniform homogenous only the homogenous solid hydrocarbons are recommended for correlation purposes with other thermal indicators

metal diagenesis in oxic marine sediments the metal nutrient relationships observed for nickel and cadmium in the deep ocean are continued at the interface between seawater and oxidizing pore water this continuum results in pore water concentrations of these metals which are only slightly greater than near bottom seawater levels manganese concentrations in these oxidizing pore waters are also extremely low less than three times bottom water in contrast release in the boundary layer produces a maximum of dissolved copper which is 10 40 times ambient seawater assuming these pore waters are at steady state flux estimates based on these measurements suggest that the manganese in todorokite rich nodules of the central equatorial pacific was not supplied by upward diffusion through pore waters below the interface most nodular nickel is precipitated with manganese while nodular copper is supplied by diffusion

paleomagnetism of the cu zn pb bearing kupferschiefer black shale upper permian at sangerhausen germany syngenetic diagenetic and epigenetic models have been proposed for the cu zn pb kupferschiefer mineralization at sangerhausen germany paleomagnetic and rock magnetic measurements have been made on 205 specimens from mine workings on the margin of the sangerhausen syncline the mineralization is richest in the 0 5 m thick upper permian 258 2 ma kupferschiefer black marly shale nine sites and dies out over 0 2 m in the underlying weisliegend sandstones three sites and overlying zechstein carbonates two sites except for one site of fault zone gypsum characteristic remanent magnetization directions were isolated for all 14 sites using alternating field and thermal step demagnetization these directions provide a negative fold test indicating that the remanence postdates jurassic fault block tilting rock magnetic measurements show that the kupferschiefer shale marks a redox front between the oxidized weissliegend sandstones and non oxidized zechstein carbonates the 14 site directions give a late jurassic paleopole at 149 3 ma it is significantly different from the paleopole reported by e c jowett and others for primary or early diagenetic rote faule alteration that gives an age of 254 6 ma on the current apparent polar wander path and is associated with kupferschiefer mineralization we suggest that the late jurassic extensional tectonic event that formed the nearby north german basin also reactivated variscan basement faults and extended them up through the overlying strata thereby allowing hydrothermal basement fluids to ascend and epigenetically mineralize the kupferschiefer shale the possibility of a 53 3 ma mineralization age is also considered

early diagenesis in differing depositional environments the response of transition metals in pore water the cycling of fe mn ni co cu cr v and mo during early diagenesis was investigated in sediments from five different depositional environments in the california borderland dissolved o2 no3 no2 and so4 were also measured at each site to establish the position of redox boundaries pertinent to this study sites were chosen to allow the comparison of several parameters of potential importance to the cycling of these metals bottom water o2 concentration sediment redox conditions cycling of metal oxide carrier phases and the relative contribution of biogenic and terrigenous material to the detrital metal flux at 10 m oxygen and above the sequence of terminal electron acceptor utilization was typical of pelagic sediments differing only in scale under these conditions the recycling of mn oxides resulted in an enriched layer near the interface at bottom water 02 concentrations 5 m mn oxides are not recycled under these conditions fe oxides and so42 are important oxidants the depth of the zone of manganese oxidation with respect to the interface affects the efficiency of metal scavenging by manganese oxides trapping and recycling of ni and co with mn oxides results in remobilization from reducing sediments and enrichment in oxic sediments scavenging of these metals is favored by a deep oxic zone in the sediments in contrast cr v and mo appear to be transported to the sediments as reduced species and are released from the sediments by oxidation the source of the reduced species is assumed to be biogenic material the accumulation of these metals is favored by reducing conditions in the sediments cu is enriched in the sediments by transport with detrital biogenic material followed by adsorption onto sediment solids cu is released at the interface and rapidly removed onto the solids at all sites except the one pelagic site at the base of the slope the magnitude of cu released in the slowly accumulating pelagic sediment exceeds the cu binding capacity of the solids resulting in pore water cu concentrations in excess of 100 nm in general metal cycling associated with the early diagenesis of sediments was observed to decouple transport processes from burial processes for the transition metals measured in this study

minas fault zone late paleozoic history of an intra continental orogenic transform fault in the canadian appalachians abstract the minas fault zone mfz defines the boundary between the avalon and meguma terranes in the canadian appalachians and is exposed in mainland nova scotia and southern new brunswick these terranes originated along the gondwanan margin but had accreted to laurentia by the middle devonian the surface trace of the mfz is adjacent to the southern margin of the latedevonian permian maritimes basin the late devonian late carboniferous evolution of the mfz involves several episodes of oblique dextral shear that resulted in basin formation and inversion and at various times the zone was the focus of magmatism regional fluid flow and mineralization in the late devonian early carboniferous asymmetric rifting accompanied by dextral shear produced two coeval sequences the horton group which is dominated by continental clastic strata and the fountain lake group which consists predominantly of bimodal volcanic rocks that overlie high level plutons emplaced along active shear zones the overall tectonic environment may have been dominated by dextral transtension along the southern margin of laurentia which corresponded with the northern flank of the rheic ocean a major change in the evolution of the minas fault zone occurred in the late mississippian early pennsylvanian and produced the e w chedabucto fault clockwise rotation of pre existing structures local zones of transtension and transpression as well as regional fluid flow and extensive mineralization this major change may reflect the onset of laurentia gondwana oblique collision the effects of which continued into the latest carboniferous with coeval development of flower structures and pull apart basins in zones of local transpression and transtension

sedimentation at manop site h eastern equatorial pacific over the past 400 000 years climatically induced redox variations and their effects on transition metal cycling gravity cores recovered from manganese nodule project site h 6 33 n 92 49 w show marked downcore variations in the abundance of calcium carbonate organic carbon opal manganese and other components deposited over the past 400 000 years variations in the downcore abundance of organic carbon which ranges from 0 2 to 1 0 can be used to hindcast redox conditions in the surface sediments over this time the results indicate that the depth to the manganese redox boundary varied from about 5 to 25 cm below the seafloor during four major cycles downcore variations in solid phase mn ni and cu can be produced by such changes in redox conditions a model which predicts that solid phase mn can be trapped and buried when the mn redox boundary migrates rapidly upward is consistent with the observed organic carbon and mn records and supports the reconstructed redox variations the history of redox variations at site h can be explained by changes with time in surface water productivity major productivity variations at the site occur over 100 kyr cycles with relatively higher productivity occurring during glacial stages thus quaternary climate changes influence surface water productivity redox conditions in sediments and the cycling of transition metals

global crustal stress pattern based on the world stress map database release 2008 the world stress map wsm project is a global compilation of information on the contemporary crustal stress field from a wide range of stress indicators the wsm database release 2008 contains 21 750 stress data records that are quality ranked using an updated and refined quality ranking scheme almost 17 000 of these data records have a c quality and are considered to record the orientation of maximum horizontal compressional stress sh to within 25 as this is almost a triplication of data records compared with the first wsm database release in 1992 we reinvestigate the spatial wave length of the stress patterns with a statistical analysis on a global 0 5 grid the resulting smoothed global stress map displays both the mean sh orientation that follows from the maximum smoothing radius for which the standard deviation is b25 and a countour map that displays the wave length of the stress pattern this smoothed global map confirms that long wave length stress patterns n2000 km exist for example in north america and ne asia these have been used in earlier analyses to conclude that the global stress pattern is primarily controlled by plate boundary forces that are transmitted into the intraplate region however our analysis reveals that rather short wave length of the stress pattern b200 km are quite frequent too particularly in western europe alaska and the aleutians the southern rocky mountains basin and range province scandinavia caucasus most of the himalayas and indonesia this implies that local stress sources such as density contrasts and active fault systems in some areas have high impact in comparison to plate boundary forces and control the regional stress pattern

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

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

fracture overprinting history using markov chain analysis windsor kennetcook subbasin maritimes basin canada abstract the deformation history of the upper paleozoic maritimes basin atlantic canada can be partially unraveled by examining fractures joints veins and faults that are well exposed on the shorelines of the macrotidal bay of fundy in subsurface core and on image logs data were collected from coastal outcrops and well core across the windsor kennetcook subbasin a subbasin in the maritimes basin using the circular scan line and vertical scan line methods in outcrop and fmi image log analysis of core we use cross cutting and abutting relationships between fractures to understand relative timing of fracturing followed by a statistical test markov chain analysis to separate groups of fractures this analysis previously used in sedimentology was modified to statistically test the randomness of fracture timing relationships the results of the markov chain analysis suggest that fracture initiation can be attributed to movement along the minas fault zone an e w fault system that bounds the windsor kennetcook subbasin to the north four sets of fractures are related to dextral strike slip along the minas fault zone in the late paleozoic and four sets are related to sinistral reactivation of the same boundary in the mesozoic

pore water distributions of dissolved copper and copper complexing ligands in estuarine and coastal marine sediments the distributions and seasonal variability of total dissolved cu tdcu and cu complexing ligands in sediment pore waters have been investigated at two contrasting sites in the chesapeake bay two ligand classes which differ on the basis of the conditional stability constants k9 of their cu complexes were detected at all depths at both sites at the sulfidic muddy mid bay sta m concentrations and values of log k9 ranged from 390 12 500 nm and 7 2 8 9 respectively for the stronger ligand class l1s and 75 6 420 nm and 6 2 7 9 for the weaker ligand class l2s at the bioturbated sandy sta s in the lower bay respective concentrations and values of log k9 ranged from 135 807 nm and 7 6 10 2 for l1s and 40 1 410 nm and 6 6 9 2 for l2s for comparison one pore water profile from a slope station off of the chesapeake bay also showed the presence of two ligand classes with respective concentrations and values of log k9 of 140 270 nm and 8 11 for l1s and 30 180 nm and 7 10 forl2s these ligands are in large excess relative to ambient tdcu concentrations 0 1 24 3 nm thereby maintaining very low inorganic cu concentrations typically 0 1 to 100 pm and a high degree of organic complexation 87 2 99 9 of cu in bay and slope sediment pore waters thus virtually all tdcu fluxing from these sediments is complexed during sediment water exchange a relatively small fraction of the tdcu is exchanged as inorganic species which are widely regarded as the most bioavailable form of cu higher ligand concentra tions at sta m suggest that sulfide or organic ligands containing reduced s contribute to the pool of complexing ligands however the exact nature and sources of the ligands in bay pore waters are not known the progressive increase in conditional stability constants of the cul 2s complexes from the mid bay to the slope sediments may reflect differences in biological or chemical processes at each site as well as differences in the type of cu complexing organic matter total ligand concentrations l1s 1 l2s are 15 to 100 times higher in the upper intervals of the pore waters relative to ligand concentrations in the bottom waters of the chesapeake bay 30 60 nm consistent with previous observations of fluxes of these ligands from the sediments to overlying waters these results suggest that sediments are potentially significant sources of cu complexing ligands to the overlying waters of the chesapeake bay and perhaps other shallow water estuarine and coastal environments copper complexing ligands released from sediment pore waters may play an important role in influencing cu speciation in overlying waters copyright 2000 elsevier science ltd

the inorganic geochemistry of cretaceous black shales dsdp leg 41 in comparison to modern upwelling sediments from the gulf of california

controls on the architecture of a triassic sandy fluvial system wolfville formation fundy basin nova scotia canada implications for the interpretation and correlation of ancient fluvial successions abstract architectural element analysis was developed to describe and reconstruct fluvial system stacking patterns and understand the controls on fluvial architecture the architecture of braided fluvial systems at the scale of channel belts is still poorly understood and upscaling from outcrop observations to basin scale architecture remains partly speculative nonetheless predictive sedimentary models are necessary to understand the connectivity of sand bodies from small scale outcrop to basin scale this contribution presents a dataset from the late triassic sandy braided fluvial system of the fundy basin nova scotia canada we describe facies associations architectural elements and stacking patterns at different scales and discuss the controls on fluvial architecture and upscaling issues the studied section shows at the base multilateral stacked channel bodies with little preservation of fine grained floodplain facies it changes upwards into multistory stacked channel bodies that form channel belt complexes intercalated with thicker floodplain deposits based on grain size evolution large scale sequences encompass several channel belt complexes controls on channel and channel belt migration or avulsion are considered to be related to autocyclic processes in contrast large scale vertical evolution and grain size variations record allocyclic signals in particular gradual grain size variations suggest a climatic control which influences the bedload transport capacity of the depositing fluvial system architectural evolution including an upward increase in the preservation of floodplain units is considered to be due to an increase in generation of accommodation space we question the existing definition of the order of large scale sixth to seventh order bounding surfaces recognized previously and highlight difficulties associated with reconstructing development of a regional fluvial system using these bounding surfaces

trace metals in metalliferous sediments manop site m interfacial pore water profiles we present data showing enrichments of metals mn cu v cr cd and ni and dissolved organic matter dom in surficial pore waters depths 1 cm at a metalliferous sediment site in the pacific we also present a model of metal release during particulate organic carbon poc oxidation and opal dissolution at the sediment seawater interface a comparison of measured interfacial metal concentrations with those predicted from the model suggest that cd ni and cr are released during oxidation of poc at the sediment seawater interface however for v cu and mn additional source s and or processes are required to account for the measured interfacial concentrations for cu recycling via interfacial remineralization and release to bottom waters with subsequent scavenging out of bottom waters by particulates probably provides the major additional source for v we suggest that in addition to some contribution from a benthic flux bottom water scavenging scenario complexation with dom at the interface serves as a trap to accumulate v released from particulates in the zone of oxygen reduction for manganese we suggest that most of the interfacial pore water content is produced from reduction of sedimentary mn iv by reactions with dom at the sediment seawater interface the calculated benthic flux of manganese as a result of this reaction may account for a large fraction of the particulate manganese rain that is apparently not preserved in the sediment at this site

geochemical disturbance and paleoenvironmental changes during the early toarcian in nw europe the early toarcian oceanic anoxic event oae is associated with a rapid and severe environmental change whose causes are still a matter of debate a new paleoenvironmental interpretation is proposed based on a multidisciplinary dataset chemical mineralogical and paleontological obtained from a borehole drilled by andra french national radioactive waste management agency in the lower toarcian of the eastern paris basin france during the earlymost toarcian tenuicostatumzone the presence ofwell oxygenated sea water is reflected by an abundant and diverse fauna alongwith paleoredox proxies u al mo al and v al typical of oxidizing conditions associated with predominant mechanical weathering on the continent at the base of the serpentinum zone an important paleoenvironmental change is marked by an initial phase of organic matter enrichment 12 toc during the negative shift of 13c carbon isotope excursion cie euxinic anoxic conditions indicated by cobalt enrichment and the development of framboidal pyrite lead to the disappearance of the benthic and pelagic fauna and alloworganic matter to be preserved in the sediments at this time the lowconcentration of paleoproductivity proxies cd p ni and zn suggests weak chemical weathering on the continent due to a rather arid climate low concentrations of sr and coccoliths are due to an input of fresh water probably coming from the arctic through the laurasian seaway thus the isolation of the paris basin from the tethyan realm and the influx of freshwater favour haline stratification and the preservation of organic matter following the cie oxygen concentration gradually increases up to amaximumflooding surface dated as coevalwith the serpentinum zone elegantulum subzone paleoproductivity proxies indicate a weak primary productivity the top of the lower toarcian is characterized by a second enrichment in organic matter 12 toc due to an important input of nutrients this enhanced primary production generates euxinic anoxic conditions in the sediment and in part of the water column leading to a high enrichment in paleoredox proxies mo u v co and causing the sudden disappearance of the benthic fauna and a progressive decline of the pelagic fauna the metal enrichment is related to intense chemical weathering on the continent due to a more humid climate

copper and manganese in hemipelagic sediments at 21 n east pacific rise diagenetic contrasts abstract relatively rapidly accumulating 7 cm kyr and organic rich 1 5 corg epr sediments near 21 n are characterized by pronounced nitrate reduction in the upper decimetre and by an enrichment of mn and increased fe al ratio in surficial sediments joint consideration of solid phase and pore water data indicates that the distributions of both mn and fe in the sediments are in disequilibrium with their respective pore water profiles precipitation of upward diffusing mn and fe is occurring at present below the enriched horizons producing perched enrichments indicative of non steady state diagenesis consideration of a high resolution 14c age vs depth curve and a decrease toward the interface from 1 51 to 1 37 wt over the top 7 cm of the corg profile suggests that the diagenetic disequilibrium evident for mn and fe may be due to a geologically recent decrease in productivity such a decrease would be manifest in the sediments by a downwardly migrating oxidation front which would progressively erode the mn and fe pore water profiles producing the existing decoupled surface enrichments in contrast to mn the distribution of cu has apparently not been perturbed by non steady state phenomena a first order decrease with depth of the dissolved copper concentration is accompanied by a first order increase in solid phase cu application of a diffusion reaction model to these data predicts a sedimentation rate of 8 cm kyr 1 which agrees well with the 14c determined rate of 7 3 cm kyr 1 implying that the pore water and solid phase distributions are in diagenetic equilibrium available evidence suggests that the major host for non detrital cu in hemipelagic sediments is authigenic nontronite because this phase appears to form slowly there may be a kinetic constraint on the amount of copper which can be incorporated authigenically in rapidly accumulating hemipelagic deposits support for this hypothesis is given by the observed inverse proportionality between the sedimentation rate and the concentration of non detrital cu in surface sediments from at least seven widespread locations in the eastern pacific it is suggested that the variation observed in the salt and caco3 free cu concentration in hemipelagic sediments is a consequence largely of the residence time of sediments at the surface where high dissolved cu concentrations prevail

characteristics and origins of coal cleat a review abstract cleats are natural opening mode fractures in coal beds they account for most of the permeability and much of the porosity of coalbed gas reservoirs and can have a significant effect on the success of engineering procedures such as cavity stimulations because permeability and stimulation success are commonly limiting factors in gas well performance knowledge of cleat characteristics and origins is essential for successful exploration and production although the coal cleat literature spans at least 160 years mining issues have been the principal focus and quantitative data are almost exclusively limited to orientation and spacing information few data are available on apertures heights lengths connectivity and the relation of cleat formation to diagenesis characteristics that are critical to permeability moreover recent studies of cleat orientation patterns and fracture style suggest that new investigations of even these well studied parameters can yield insight into coal permeability more effective predictions of cleat patterns will come from advances in understanding cleat origins although cleat formation has been speculatively attributed to diagenetic and or tectonic processes a viable mechanical process for creating cleats has yet to be demonstrated progress in this area may come from recent developments in fracture mechanics and in coal geochemistry

enrichment of redox sensitive trace metals u v mo as associated with the late hauterivian faraoni oceanic anoxic event the faraoni level is a short lived oxygen deficient event that took place during the latest hauterivian in order to improve our understanding of the palaeoenvironmental conditions that occurred during this event we have analysed the contents of several redox sensitive trace elements u v mo as co cd cu zn ni pb cr from bulk limestone samples of late hauterivian early barremian age from three reference sections u v mo and as show consistent and significant enrichments during the faraoni event whereas the other redox sensitive trace elements analysed here are not systematically enriched in order to explain this discrepant behaviour we propose that the faraoni level was deposited during a period of anoxic conditions near the sediment water interface the distinctive peaks in u v mo and as contents are traceable throughout the three studied sections and represent a good correlation tool which helps to identify the faraoni level and its equivalents in the western tethyan realm and outside of the tethys for example a peak in u contents in upper hauterivian sediments of the northwestern pacific realm odp leg 185 site 1149 may well be an expression of the faraoni event in this particular basin

redox productivity and paleotectonic studies in the southern tethyan margin of northern tunisia abstract in northern tunisia the cenomanian turonian sediments are characterized by organic rich material these deposits are commonly attributed to the bahloul formation and record the worldwide oae2 event in general the bahloul formation is related to paleogeographic and tectonic events these results suggest that multiple causes including primary productivity sea level changes climatically driven organic carbon burial and structural framework this formation is composed of three differentiated units the first unit u1 is composed of laminated limestones with small intercalations of marls caco 3 varies between 48 and 83 the second unit u2 is characterized by very thin beds of marls argillaceous and laminated limestones caco 3 ranging from 57 to 85 lastly the third unit u3 is represented by a set of thick black shales with some levels of marls isotopic 13 c carb study shows a large positive excursion in the bahloul formation it is characterized by three peaks that exceed 3 first and the second peaks are identified at the lower unit u1 with isotopic values recording 3 2 and 3 3 respectively third peak is recorded in the middle of the unit u2 and it attains 3 2 this section records important toc values reaching up to 3 84 in unit u1 with average values exceeding 3 the rock eval data shows a marine organic matter with kerogen type ii 429 max 435 c which can generate oils a significant enrichment of major and trace elements are also recorded which took place during the deposition of the bahloul formation in general high levels of p cu and ni indicate a high surface primary productivity which led to the accumulation of large quantities of organic matter on the sea floor

a 48 m y history of fracture opening temperature and fluid pressure cretaceous travis peak formation east texas basin quartz cement bridges across opening mode fractures of the cretaceous travis peak formation provide a textural and fluid inclusion record of incremental fracture opening during the burial evolution of this low porosity sandstone incremental crack seal fracture opening is inferred based on the banded structure of quartz cement bridges consisting of up to 700 cement bands averaging 5 m in thickness as observed with scanning electron microscope cathodoluminescence crack seal layers contain assemblages of aqueous two phase fluid inclusions based on fluid inclusion microthermometry and raman microprobe analyses we determined that these inclusions contain methane saturated brine trapped over temperatures ranging from 130 c to 154 c using textural crosscutting relations of quartz growth increments to infer the sequence of cement growth we reconstructed the fluid temperature and pore fluid pressure evolution during fracture opening in combination with published burial evolution models this reconstruction indicates that fracture opening started at ca 48 ma and above hydrostatic pore fluid pressure conditions and continued under steadily declining pore fluid pressure during partial exhumation until present times individual fractures opened over an 48 m y time span at rates of 16 23 m m y these rates suggest that fractures can remain hydraulically active over geologically long times in deep basinal settings

trace metal remobilization in the interstitial waters of red clay and hemipelagic marine sediments interstitial water samples from the guatemala basin and the coast of baja california have been analyzed for manganese iron copper nickel and nitrate the data provide a systematic look at changes in trace metal diagenesis proceeding from red clay to highly reducing nearshore sediments in red clay sediments the nitrate concentrations suggest that only aerobic respiration is occurring manganese and iron are below detection nickel concentrations remain the same as in bottom seawater but copper shows a pronounced maximum just at the sediment water interface proceeding to hemipelagic sediments denitrification becomes increasingly important and manganese and iron remobilization occur in the sediments the linear manganese and nitrate profiles suggest regions of production or consumption separated by zones of diffusion this differs from the conventional picture of a continuous series of reactions within the sediments manganese reduction always occurs before iron reduction the pore water nickel correlates well with manganese in these sediments suggesting that nickel is associated with mno2 in the solid phase the pore water flux ratio of manganese and nickel agrees well with the ratio in solid phase authigenic oxides copper still displays a core top concentration maximum as well as a second maximum associated with the remobilized manganese the calculated ratio of the cu c flux ratios support the argument for copper remobilization during organic carbon oxidation comparison of the upward and downward diffusive fluxes with the rate of copper buried by sedimentation shows that at least half of the copper buried must be of diagenetic origin and less than 25 of the copper reaching the sediments is buried

biogenic origin of intergrown mo sulphide and carbonaceous matter in lower cambrian black shales zunyi formation southern china abstract the lower cambrian zunyi formation in southern china hosts complex intergrown phases of mo sulphides and anthracite like carbonaceous matter and graphite mosc pyrite and ni sulphides these sulphides occur in a few centimeters thick polymetallic stratiform layer in black shales above phosphorites cherts dolomites and barite the ore horizon contains 7 wt mo 2 wt ni 19 wt s and 13 wt c org and c tot co 2 58 wt 14 wt cao 1 2 wt as 2000 ppm se 5400 ppm zn 450 ppm u and v and up to 1 ppm platinum group elements three types of mosc phases always including framboidal pyrite are distinguished 1 rounded structures few hundred microns large 2 relict inclusions in diagenetic pyrite 3 grains interstitial to sulphurised and phosphatised organic matter at the nanoscale mosc is represented by nanometric porous rounded structures of mos 2 finely intergrown with carbonaceous matter of typical nano onion structures mosc also contains nanocrysts of quartz clays ca sulphate carbonate and ni sulphides micro raman spectroscopy shows that the carbon phase has a maturation grade of anthracite indicating temperatures below 300 c mosc is mainly composed of 25 wt mo 23 wt s 5 6 wt fe 2 5 wt ni 33 wt c 1 5 wt o 0 6 wt n and several hundreds of ppm of cu as se sb pd zn co and sn electron energy loss spectra show that n is related to nanosized carbonaceous matter the mean c n ratio 57 of mosc is similar to those observed in marine organic matter and those reported from zooplankton at hydrothermal vents the mineralized shales are crosscut by hydrothermal veins composed of carbonate or barite always associated with quartz apatite and fe and zn sulphides a paragenesis also observed as nanocrysts in mosc although mo originated from seawater its extreme concentration is due to an enhanced growth of bacterial consortia in a diffuse hydrothermal vent system these consortia may be dominated by nitrogen fixing and mo dependant hyperthermophilic or mesophilic species containing nitrogenase composed also of mo s fe organic matter decay led thus to the formation of mosc and the included framboidal pyrite

vanadium accumulation in carbonaceous rocks a review of geochemical controls during deposition and diagenesis abstract published data relevant to the geochemistry of vanadium were used to evaluate processes and conditions that control vanadium accumulation in carbonaceous rocks reduction adsorption and complexation of dissolved vanadium favor addition of vanadium to sediments rich in organic carbon dissolved vanadate v v species predominate in oxic seawater and are reduced to vanadyl ion v iv by organic compounds or h 2 s vanadyl ion readily adsorbs to particle surfaces and is added to the sediment as the particles settle the large vanadium concentrations of rocks deposited in marine as compared to lacustrine environments are the result of the relatively large amount of vanadium provided by circulating ocean water compared to terrestrial runoff vanadium rich carbonaceous rocks typically have high contents of organically bound sulfur and are stratigraphically associated with phosphate rich units a correspondence between vanadium content and organically bound sulfur is consistent with high activities of h 2 s during sediment deposition excess h 2 s exited the sediment into bottom waters and favored reduction of dissolved v v to v iv or possibly v iii the stratigraphic association of vanadiferous and phosphatic rocks reflects temporal and spatial shifts in bottom water chemistry from suboxic phosphate concentrated to more reducing euxinic conditions that favor vanadium accumulation during diagenesis some vanadium organic complexes migrate with petroleum out of carbonaceous rocks but significant amounts of vanadium are retained in refractory organic matter or clay minerals as carbon in the rock evolves toward graphite during metamorphism vanadium is incorporated into silicate minerals

tracing of anthropogenic zinc sources in coastal environments using stable isotope composition abstract the use of zinc isotopes to trace anthropogenic sources in coastal areas has been tested in this study we determined the stable isotopic composition of zinc in sediment cores suspended particulate matter spm and rocks collected at the sepetiba bay southeastern brazil an estuarine lagoon heavily impacted by metallurgic activities these isotopic signatures were compared with those from willemite ore which represent the main mineral refined by the major industrial source of zinc the aim was to test if this tracer system enables to identify sources and sinks of anthropogenic zinc and to reconstruct the temporal and spatial evolution of zinc contamination the zinc isotopic compositions expressed using the 66zn notation relative to the jmc 3 0749 l solution showed significant variations in the sediment cores the spm and willemite ore minerals ranging between 0 01 and 1 15 spatial and temporal analysis of sediments samples fit well in a model of mixing involving three main end members i terrestrial background 66znjmc 0 28 0 12 2 ii marine detrital material 66znjmc 0 45 0 03 2 and iii a major anthropogenic source associated with electroplating wastes released into the bay 66znjmc 0 86 0 15 2 sediment cores collected in the mud flats showed high correlation between 66zn and zinc enrichment factors suggesting good preservation of the isotopic records of natural and anthropogenic sources the sediment core sampled from a mangrove wetland located in a zone impacted by the metallurgy presented levels of zinc up to 4 sediment dry weight and preserved the isotopic signatures of electroplating wastes despite evidences that post depositional processes slightly changed the isotopic signatures in some layers from this core toward heavier 66znjmc values above 1 0 a two component mixing model suggests contributions of this major anthropogenic zn source up to nearly 80 during periods of electroplating activities our work suggests that zn isotope compositions of sediments are reliable tracers of anthropogenic sources and therefore can be useful to improve environmental monitoring efforts in coastal systems

natural hydraulic fracturing of tight gas sandstone reservoirs piceance basin colorado natural fractures form preferred pathways for basinal fluid flow and associated heat and mass transport in gas sandstone reservoirs with low matrix permeability fractures provide flow pathways between organic rich source and reservoir layers during gas charge and between matrix pores hydraulic fractures and the well bore during production while the formation of natural fractures has previously been associated with gas generation and pore fluid pressure increase through a process referred to as natural hydraulic fracturing other driving mechanisms such as stress changes by tectonic or exhumation processes remained viable alternatives to test whether these mechanisms contributed to fracture development we investigated the spatial and temporal distribution of fracture formation and its relationship to gas generation migration and charge in sandstone of the cretaceous mesaverde group across the entire production interval on a basinwide scale using fluid inclusion microthermometry of crack seal fracture cement formed concurrently with fracture opening we observed temperature trends that when compared with temperature evolution models of the formation date fracture formation between 41 and 6 ma in the northern and between 39 and 6 ma in the southern piceance basin the onset of fracture formation 20 30 m y prior to maximum burial eliminates changes in stress state associated with exhumation as a mechanism for triggering the onset of fracture formation instead calculated paleo pore fluid pressures of 40 90 mpa 5800 13 000 psi during fracture opening and the presence of methane rich inclusions in fracture cement suggest that fracture formation was aided by high pore fluid pressures during gas generation in organic rich shales and coals and associated charging of adjacent and interlayered sandstone reservoirs a 10 20 m y age progression in the onset of fracture formation from deeper to shallower horizons of the mesaverde group is consistent with gas generation and onset of fracture formation activated by burial temperature with limited upward migration of gas at this stage of reservoir evolution this age progression with depth is inconsistent with fracture formation triggered by changes in stress conditions associated with tectonic or structural processes expected to affect the entire formation synchronously our observations are thus most consistent with fracture formation by natural hydraulic fracturing in response to gas generation in interbedded source layers and reservoir charge based on widespread observations of fractures with similar structural and diagenetic attributes we consider natural hydraulic fracture formation in response to thermocatalytic gas generation to be a fundamental mode of brittle failure in otherwise structurally quiescent basins

geochemical characteristics across the oxic anoxic interface rote faule front within the kupferschiefer of the lubin sieroszowice mining district sw poland abstract samples of profiles from lower zechstein in the lubin sieroszowice mining district sw poland were collected within and at different distance to the oxidized facies rote faule developed within the zechstein strata around the zary pericline the samples include kupferschiefer underlying weissliegendes sandstone and overlying zechstein limestone from rote faule zones adjacent cu mineralized strata and drill cores from the pb zn mineralized zone more distant to the rote faule front the kupferschiefer samples show differences in ore paragenesis and composition of organic matter which are accompanied by variations in base metal and trace element contents and isotope ratios of organic carbon and carbonates the results from rock eval analyses provide evidence for an oxidative alteration of organic matter in kupferschiefer samples within and adjacent to the rote faule zones related to base metal mineralization the extent of this alteration is reflected by differences in the temperature of maximum pyrolysis yield t max hydrogen and oxygen indices hi oi in contrast to kupferschiefer from pb zn mineralized areas organic matter is characterized by lower hydrogen equivalents and by higher t max values the changes in the isotopic composition of organic carbon and carbonates reflect the alteration of organic matter kerogen within or close to rote faule zones is enriched in 13 c caused by the preferential release of isotopically light organic compounds through progressive degradation of organic matter the opposite tendency towards lower 13 c values of calcite provides evidence for organic matter remineralization isotopic exchange reactions of carbonate with the isotopically distinct oxidizing brines at temperatures between 100 and 120 c caused decreasing 18 o values of calcite the regional zonation in the kupferschiefer with respect to sulfide paragenesis and base metal composition in the mines is explained by metal precipitation from oxidizing brines through decreasing eh conditions during the infiltration of the brines into the reduced kupferschiefer relationships between selected trace elements organic carbon and sulfur contents and hi values are consistent with that model of ore formation

orthogonal cross joints do they imply a regional stress rotation abstract orthogonal cross joints extend across intervals between systematic joints in brittle sedimentary strata and abut the systematic joints at about 90 angles these joints typically form a ladder like pattern if viewed on a bedding surface a common interpretation is that orthogonal cross joints define the orientation of the regional stress field during their formation least compressive stress perpendicular to the joints it follows that they indicate a rotation of regional principal stresses by 90 after the formation of the systematic joints using a three dimensional boundary element code poly3d we considered a simple geologic case of vertical systematic fractures developing in horizontal strata under a triaxial remote load with the maximum principal tensile stress being horizontal and perpendicular to the strike of the fractures the intermediate principal stress being horizontal and parallel to the strike of the fractures and the least principal tensile stress i e maximum compressive stress being vertical the results show that the local maximum principal stress is first perpendicular and then parallel to the strike of the systematic fractures as the ratio of fracture spacing to height changes from greater than to less than a critical value when the horizontal remote principal stress ratio the ratio of the intermediate remote principal stress to the maximum remote principal stress under the sign convention of positive for tensile stresses is greater than a threshold value 0 2 thus the fracturing process changes from infilling of systematic fractures to the formation of orthogonal cross fractures this provides an alternative mechanism for the formation of orthogonal cross joints that does not require a systematic rotation of the regional stress field by 90 the critical spacing to height ratio for the local principal stress switch is independent of the least remote principal stress i e overburden it increases nonlinearly with increasing ratio of the horizontal remote principal stresses and decreases nonlinearly with increasing poisson s ratio of the material

metal accumulation during and after deposition of the kupferschiefer from the sangerhausen basin germany abstract a densely sampled profile 58 cm in thickness composed of 13 samples of the kupferschiefer and overlying zechstein carbonates from the sangerhausen basin germany has been analysed by various geochemical and microscopic methods in order to clarify the mechanism of base metal accumulation in this location the kupferschiefer is only slightly influenced by the hematite bearing oxidized fluids called rote faule the determination of facies dependent parameters along the profile indicates that kupferschiefer from the sangerhausen basin was largely deposited in a marine environment only at the beginning of kupferschiefer sedimentation did euxinic conditions prevail the bottom part of the profile is significantly enriched in trace elements such as cu ph zn as co ag and u the cu concentration amounts to 19 88 wt post depositional oxidation of the organic matter is observed only in the transition zone between the kupferschiefer and the zechstein conglomerate indicating the influence of ascending oxidizing brines microscopic analyses show that only fe sulfides form framboidal textures cu minerals are present along the total profile preferentially in fractures and as patchy structures composed of chalcocite chalcopyrite and bornite in the highly mineralized bottom section cu sulfides are associated with pyrobitumen sparry calcite and arsenopyrite results from maturation studies of organic matter suggest that the maximum temperature affecting the kupferschiefer was approximately 130 c a 3 step process of metal accumulation is proposed during deposition of the sediment framboidal pyrite and pyrite precursors were precipitated by bacterial so 4 2 reduction bsr during diagenesis the pyrite and pyrite precursors were largely replaced by mixed cu fe minerals and by chalcocite pr in the section with very high cu contents 8 reduced sulfur from fe sulfides was not sufficient for precipitation of cu and other trace metals from ascending solutions in this part of the profile thermochemical so 4 2 reduction tsr occurred after pyrite replacement as indicated by the presence of pyrobitumen and sparry calcite

estimating fracture trace intensity density and mean length using circular scan lines and windows fracture characterization protocols that reduce sampling bias are likely to yield higher quality input for exploration and development decisions when dealing with naturally fractured reservoirs a new set of estimators for fracture density intensity and mean trace length corrects for sampling biases and provides a useful integrated description for bulk aspects of a fracture network these estimators are based on counts of intersections between fracture traces and circular scan lines and of trace terminations in circular windows application to synthetic fracture patterns with known parameters validates the use of the new estimators which are then applied to natural fault trace maps from seismic volumes and joint trace maps from rock pavements the new estimators are distribution independent and eliminate the effects of orientation censoring and length biases which limit the effectiveness of other sampling techniques estimator accuracy improves as sample size increases particularly for larger circles that exceed a fracture defined block size estimator accuracy for mean trace length improves when the sample exceeds threshold count values for fracture terminations based on guidance from the analysis of similar synthetic patterns these new estimators also provide both inputs and independent checks of predictions for fracture generator programs used to model fracture populations in a rock volume

processes that control mineral and element abundances in shales abstract a shale s composition can be used to infer physical chemical and biological processes that have acted on it over its life history and this knowledge is used to surmise conditions at the time when each process was active this review lists the most important processes that control shale mineral and element abundances during each of the five stages of its life history 1 during weathering transport and deposition the most important processes are chemical weathering hydraulic sorting and mixing adsorption reverse weathering and incorporation of organic matter and biominerals 2 during early diagenesis the most important processes are exchange across the water sediment interface compaction microbial respiration mineral transformations and concretion formation 3 during burial diagenesis the most important processes are compaction catagenesis and metagenesis and mineral transformations 4 during exhumation the most important processes are decompaction brine invasion groundwater penetration and microbial respiration 5 during weathering the most important processes are organic matter oxidation mineral oxidation and hydrolysis groundwater transport and disaggregation this classification of processes provides a way to envision how concurrent and consecutive processes that occurred over a shale s life history have affected its mineralogy and chemical composition

role of organics and methane in sulfide ore formation exemplified by kupferschiefer cu ag deposits poland abstract organic material has been involved in the formation of the kupferschiefer cu ag sulfide deposits in poland in several different ways and at several stages in their development during sedimentation a mixture of continental humic material and marine algal material was concentrated in the euxinic peri marine kupferschiefer black shale environment 6 c org having the black shale directly on the continental redbeds below effected a strong redox gradient across which the ore is located early diagenetic pyrite marcasite framboids and nodules were formed through bacteriogenic reduction of sulfate from seawater derived pore waters metal zones and variations in organic composition indicate that upwelling oxidized ore fluids were reduced by organic material and fe sulfides in the shale inducing the precipitation of cu sulfides a network of natural hydrofractures formed by generation of hydrocarbon related gases in the shale allowed the ore fluids to penetrate the otherwise impermeable caprock and concentrate sulfides natural gases also migrated up from carboniferous coal source beds and accumulated in the c org free eolian sandstone below the kupferschiefer shale geologic and cathode luminescence evidence indicates that the ch 4 reacted with anhydrite cement to form distinctive calcite cements and h 2 s which precipitated cu sulfide cements although 13 c and 34 s values are inconclusive quartz replacement concomitant with sulfide formation in the kupferschiefer and proterozoic nonesuch ores michigan u s a and in athabasca oil sands canada provides field support that silica organic complexing is a mechanism that accelerates dissolution and increases solubility of quartz at low temperature and neutral ph

thermal maturity of the lower carboniferous horton group nova scotia abstract the thermal alteration index tai obtained from spore colouration is a useful maturity indicator that may be obtained from palynological preparations thermal maturity is an important parameter in determining the hydrocarbon potential of the lower carboniferous lacustrine and fluviatile sediments of the horton group and coeval rocks of nova scotia samples studied from fifty two separate localities indicate a wide range in thermal maturity from low tai 2 to 3 to high tai 4 to 5 variation in depth of burial was probably the main factor responsible for the regional differences in thermal maturity the thickness of horton sedimentation varied considerably in a series of half grabens as did the overburden of post tournaisian lower carboniferous upper carboniferous permian and possibly triassic rocks the organic matter in most samples is composed of exinous type ii and woody and coaly material types iii and iv locally in a few localities amorphous algal material type i consisting of botryococcus sp is common the composition of the organic matter and the thermal maturity data suggest that in most of the study area rocks of the horton group are in the dry gas generation zone although in some areas oil generation may have taken place in a few localities where the thermal maturity is high the organic matter has been altered beyond the dry gas preservation limit

fracture porosity creation and persistence in a basement involved laramide fold upper cretaceous frontier formation green river basin usa fracture hosted porosity and quartz distribution along with crack seal texture and fluid inclusion assemblage sequences in isolated bridging quartz deposits show that open fractures can persist through protracted burial and uplift in foreland basins fractures oriented at a high angle to current maximum compressive stress remain open and were weak mechanical discontinuities for millions of years even at great depth upper cretaceous frontier formation sandstones in the basement involved laramide table rock anticline eastern greater green river basin wyoming sampled by two horizontal wells cut parallel or nearly parallel to bedding and at a high angle to steeply dipping fractures have 41 5 m of rock in four cores at depths of 4538 4547 m cores intersect older e striking set 1 fractures are abutted by or locally cross cut by n striking set 2 fractures both sets contain quartz and porosity sequenced using quartz crack seal cement texture maps set 1 fluid inclusion assemblage fia trapping temperatures increase progressively from 140 to 165 c then decrease to c 150 c compatible with fracture opening over c 15 ma during rapid burial followed by uplift in eocene oligocene time set 2 opened at c 160 c probably near maximum burial after a period of quiescence set 2 reopened at c 5 ma at c 140 c on a cooling trajectory intermittent set 2 movement could reflect local basement involved fault movement followed after a pause by further set 2 reactivation in the modern stress field during uplift interpretations are sensitive to available burial thermal histories which have considerable uncertainty

geochemistry of the kupferschiefer poland cu pb and zn are the main metals occurring in sulfides in the kupferschiefer they are arranged in the three distinct zones around rote faule in the order cu pb and zn copper zones are enriched in transition metals i e ag ni co v and mo ranging from 600 to 1500 ppm they are concentrated especially in the bottom part of black shale re is associated with mo the re mo ratio in cu pb and k castaingites is about 1 70 in copper zones near the contact with lead zones au platinum group metals pgm and u are concentrated ranging from traces to several hundred ppm the main mechanism of concentration of transition metals was catalytic autooxidation and dehydrogenation of organic matter the noble metals form either independent minerals or are present in organic matter and thucholite in the lead zones at the contact with cu zones an increased content of ag 100 1500 and hg 5 800 ppm is present the average hg content for the black shale of the zone is 61 ppm a natural gas exploited from the rotliegendes beneath the kupferschiefer carries in aerosols significant amount of pb cu mn fe ag and hg this suggests the rotliegendes as a pathway or as a source of metals for the kupferschiefer the presence of k castaingite intergrown with silvinite kcl may suggest k dominated brines as the mineralizing fluids

multiproxy reconstruction of oceanographic conditions in the southern epeiric kupferschiefer sea late permian based on redox sensitive trace elements molybdenum isotopes and biomarkers abstract the key drivers controlling the redox state of seawater and sediment pore waters in low energy environments can be inferred from redox sensitive trace elements rste molecular biomarkers and trace metal isotopes here we apply a combination of these tools to the upper permian kupferschiefer t1 from the thuringian basin deposited in the southern part of the semi enclosed kupferschiefer sea enrichment patterns of the rstes molybdenum mo and uranium u as well as biomarker data attest to the rapid development of euxinic conditions in basin settings during early t1 times which became progressively less extreme during t1 deposition the evolution of redox conditions in basinal settings and the associated delay in the onset of euxinia at more shallow marginal sites can be attributed to the interaction of sea level change with basin paleogeography euxinia in the southern kupferschiefer sea did not lead to near quantitative depletion of aqueous mo possibly due to short deepwater renewal times in the thuringian basin low aqueous h 2 s concentrations the continuous resupply of rste during transgression and declining burial rates of rstes throughout t1 times drawdown of rste is however indicated for euxinic lagoon environments moreover admixture of freshwater supplied to these lagoons by rivers strongly impacted local seawater chemistry the highest mo isotope compositions of 1 70 in basin sediments allow a minimum kupferschiefer sea seawater composition of 2 40 to be estimated this composition is similar to the 2 30 estimate for the late permian open ocean and confirms a strong hydrographic connection between the epeiric kupferschiefer sea and the global ocean the substantial variation in mo isotope signatures is paralleled by diagnostic shifts in biomarkers responding to oxygenation in different parts of the water column water column chemistry has been affected by variation in sea level hydrodynamic restriction riverine freshwater influx and evaporitic conditions in shallow lagoons elucidation of the relative role of each driving factor by a single geochemical proxy is not feasible but the complex scenario can be disentangled by a multiproxy approach

influences of secondary oxidation and sulfide formation on several maturity parameters in kupferschiefer vitrinite reflectance and methylphenanthrene indices are important maturity parameters for coal and other sedimentary organic matter they have been widely used for determining the maturity of organic matter in kupferschiefer however during the study of organic matter in kupferschiefer it has been found that vitrinite reflectance and methylphenanthrene indices were influenced by oxidizing fluids and sulfide formation in order to study the influence degree on maturity parameters three kupferschiefer profiles from the konrad polkowice and sangerhausen mines were analysed by microscopic and geochemical methods the results indicate that the kupferschiefer in the studied areas was deposited in normal marine and euxinic environment according to organic facies parameters the kerogen belongs to type ii under the influence of secondary oxidation organic matter was altered from type ii to type iii in the oxidized samples the values of vitrinite reflectance are clearly higher and the values of methylphenanthrene indices are lower than those of non oxidized samples because of the depletion of alkylated phenanthrenes the actual maturity can be calculated by revision of measured vitrinite reflectance and calculated vitrinite reflectance in the oxidized kupferschiefer samples in high mineralized samples hydrogen donation for thermochemical sulfate reduction occurred in alkylated phenanthrenes and resulted in a decrease of methylphenanthrene index values during kupferschiefer mineralization the methylphenanthrene index values in these samples can be calculated empirically

carboniferous marsh foraminifera from coal bearing strata at the sydney basin nova scotia a new tool for identifying paralic coal forming environments assemblages of agglutinated foraminifera from the carboniferous late westphalian to stephanian coal bearing strata of the sydney basin cape breton island documented for the first time in 150 yr of investigation of the nova scotian coal basins indicate that deposition took place on an extensive coastal platform not in a fluviolacustrine setting as previously suggested the assemblages contain representatives of genera that are widely distributed in modern estuarine and marsh environments allowing us to determine carboniferous paleoenvironments with unusual confidence seat earths beneath several coal seams contain assemblages dominated by trochammina which suggests deposition within vegetated zones analogous to modern high marsh environments found within the upper half of the tidal range a coal seam split and a coarse siltstone contain assemblages dominated by ammobaculites and ammotium which indicate paleoenvironments analogous to modern low marsh and estuarine environments mixed assemblages of trochammina ammobaculites and ammotium also indicate estuarine low marsh depositional environments detailed analysis of foraminiferal biofacies assists in the recognition of marine influence during deposition of these carboniferous rocks and may help distinguish areas of sulfur rich coal the findings indicate that environmental and morphological conservatism has characterized agglutinated marsh foraminifera for the past 300 m y

tectonic evolution of the fundy rift basin canada evidence of extension and shortening during passive margin development seismic and field data show that the fundy rift basin of southeastern canada experienced two distinct episodes of deformation during mesozoic time the first episode during middle triassic to early jurassic time was extensional rifting associated with nw se extension reactivated ne trending paleozoic compressional structures as normal faults forming the northwestern boundary faults of the fundy basin displacements on the low angle boundary faults locally exceeded 10 km rifting also reactivated east trending paleozoic compressional structures as oblique slip faults with normal and sinistral strike slip components forming the northern boundary faults of the fundy basin several kilometers of sediments and lava flows filled the basin during rifting the second deformational episode occurred during or after early jurassic time and probably before or during early cretaceous time inversion associated with nw se shortening occurred along all faulted margins of the fundy basin the northwestern boundary faults experienced several kilometers of reverse displacement broad anticlines developed within their hanging walls and the fundy basin acquired its synclinal form the northern boundary faults of the fundy basin became oblique slip faults with reverse and dextral strike slip components gentle synclines tight anticlines and faults with reverse separation deformed the synrift strata near the northern margin of the fundy basin neither collision nor subduction zones existed near the fundy basin during mesozoic time hence we believe that tectonic processes associated with seafloor spreading e g incipient ridge push forces continental resistance to plate motion produced the shortening in the fundy basin shortening occurred during the transition from rifting to drifting as north america separated from northern africa and or during the early stages of drifting as the seafloor spreading centers of the north atlantic propagated northward

the role of organically bound sulphur in stratiform ore sulphide deposits abstract low and high molecular weight organic sulphur compounds were analyzed in a selected number of samples of the permian kupferschiefer poland their significant presence in these mature samples supports the hypothesis that during deposition and shortly thereafter labile organic sulphur compounds must have been very abundant this assumption has led to a new model for metal accumulation based on a slow and gradual release of sulphur from these labile organic sulphur compounds during increasing diagenesis

curving cross joints and the lithospheric stress field in eastern north america cross joints are late formed nonsystematic fractures that extend across intervals between systematic joints traces of such cross joints are seen on bedding plane surfaces of devonian catskill clastic sedimentary rocks of the appalachian plateau of western new york state where the maximum horizontal principal stress s h is oriented n65 e as indicated by in situ stress measurements between pairs of closely spaced systematic joints traces of cross joints are commonly planar and orthogonal to the preexisting joints however in the mid region between some widely spaced systematic joints in western new york cross joints strike parallel to the s h of the present lithospheric stress field but then curve to abut the preexisting joints at right angles a curving trace reflects a local perturbation of the regional stress field in the vicinity of preexisting joints and the perpendicular termination indicates that the preexisting joints were open depending on their age the strike of the mid region of curving cross joints denotes the orientation of either the neotectonic stress field or its tertiary predecessor in the north american lithosphere

the origin of a mississippi valley type deposit in the viburnum trend southeast missouri petrologic and isotopic studies of the base metal sulfide mineralization in the buick mine have established the following paragenesis an early stage of fine grained pyrite and marcasite replaced the dolostone host rock the iron disulfides and dolostone were replaced by sphalerite during the main stage of sphalerite precipitation delta 34 s sp 16 5 to 19 0ppm following the sphalerite two main stages of galena were precipitated a cuboctahedral stage delta 34 s gn 21 3 to 10 0ppm during which galena replaced dolostone and sphalerite and grew in vugs in the dolostone and in the sphalerite and a cubic stage delta 34 s gn 10 5 to 0 9ppm the two stages of galena precipitation were separated by a period during which the main stage of sphalerite and the cuboctahedral galena were partially dissolved and bladed marcasite delta 34 s mc 2 3 to 4 1ppm was precipitated and followed by a period of mild etching of the cubic galena minor amounts of pale sphalerite delta 34 s sp 14 0 to 16 5ppm were then precipitated white and colorless rhombs of dolomite were precipitated at the same time as some of the main stage of sphalerite the cubic galena and the pale sphalerite after the pale sphalerite was precipitated chalcopyrite quartz and siegenite were precipitated followed by calcite and finally kaolinite the paragenetic and textural data for both galena and sphalerite in the buick mine strongly suggest that these minerals were precipitated and dissolved repetitively during ore formation similar textural evidence for galena reported by other workers for different mines in the viburnum trend implies that repetitive precipitation and dissolution of galena was probably an important process during the formation of the entire viburnum trend fluid inclusions in late quartz crystals coprecipitated with chalcopyrite have filling and freezing temperatures within the ranges reported for sphalerite from other parts of the viburnum trend demonstrating that the ore forming solutions in the viburnum trend were probably at temperatures in the range 105 degrees to 141 degrees c assuming a maximum pressure correction of about 11 degrees c and were extremely saline containing about 4 0 to 5 0 molal chloride consideration of typical chemical analyses of fluid inclusions from other mississippi valley type deposits suggests that the maximum likely concentration of dissolved co 2 in the ore forming solutions was about 0 05 molal at these concentrations the ore forming solutions that travelled to the site of deposition could have had ph9s about two units less than neutral and still have been in equilibrium with dolomite or calcite the ranges of sulfur and lead isotopic compositions of galena from the buick mine are very similar to those established by earlier studies of the old lead belt and adjacent subdistricts however the correlation of isotopically lighter sulfur with more radiogenic lead is much stronger for the viburnum trend suggesting that galena was precipitated from many solutions each of which carried lead and sulfur together and had different lead and overall sulfur isotopic compositions the textural paragenetic and isotopic data for the buick mine cannot be easily explained either by a sulfate reduction model in which sulfate was reduced by organic matter or methane or mixing models in which base metals and reduced sulfur were transported separately to the site of deposition instead the data strongly support a reduced sulfur model for ore formation according to which the base metals were transported together with reduced sulfur as h 2 s in the same solutions to the sites of deposition the reduced sulfur model is also supported by a theoretical calculation of the solubilities of galena and sphalerite which demonstrate that low but economically significant concentrations of lead or zinc could have been transported as chloride complexes together with equivalent concentrations of reduced sulfur at temperatures of 100 degrees to 150 degrees c and ph9s of one to two units less than neutral and could have been precipitated by ph increases cooling or dilution at the sites of deposition

holocene sediment budgets for the basins of the california continental borderland abstract two holocene sediment budgets have been compiled for the california continental borderland the first detailed budget includes the six northern inshore and central basins that capture almost 40 of the total sediment input to the entire borderland in the second budget the data for the six basins has been added to estimates of accumulation for the remaining borderland area to produce a total regional budget of lower precision than the smaller six basin region natural river influx to the borderland approximates 13 1010 tons for the holocene epoch and biological input has been estimated at about 2 1010 tons eolian and ocean current influx have each been estimated at about 1 1010 tons in sum the total deposited volume for 104 yrs is about 14 1010 tons and the estimated total influx is of the order of 17 1010 tons which suggests that a net of 1 3 101010 tons for the holocene high sea level period the six high accumulation rate basins are located adjacent to the largest river sources the major zones of coastal upwelling and the main northern eddies of the california current these high accumulation sites are typically also areas where mass movement and fan development are localized the sediment accumulation rate is much larger than subsidence rate and flat floored basins are typical in contrast the southern and outer low accumulation basins are areas of draped sediment with accumulation rate less than subsidence rate and are the sites of penecontemporaneous deformation of the accumulating fine hemipelagic sediments few fans or major mass movements are seen significant sedimentation is mainly confined by topography to less than 20 of total margin area thus the moderate to low total sediment influx is amplified by the restricted receiving area to produce locally thick deposits of limited areal extent this pattern is characteristic of neogene southern california basins and illustrates that stratigraphic thickness is not a valid indicator of sediment influx

saddle dolomite as a by product of chemical compaction and thermochemical sulfate reduction petrographic stable and radiogenic isotope trace element and fluid inclusion data from the devonian nisku reef trend in the subsurface of alberta canada suggest that saddle dolomite was a by product of chemical compaction and thermochemical sulfate reduction in subsiding dolomitized rocks furthermore thermochemical sulfate reduction may be representative of other processes that increase the amount of saddle dolomite via an increase in carbonate alkalinity the data also confirm that saddle dolomite is most likely to form at elevated temperatures from hypersaline brines

petrography of thoriferous hydrocarbon nodules in sandstones and their significance for petroleum exploration nodules of thorium rich hydrocarbon are recorded in sandstone sequences from several basins the hydrocarbon nodules contain mineral inclusions particularly of thorite or monazite there is evidence both for accretion of hydrocarbons around detrital heavy mineral grains and for epigenetic growth by interaction of hydrocarbons with thorium bearing fluids both mechanisms depend upon the precipitation of solid hydrocarbons induced by irradiation from thorium the nodules exhibit aggressive replacement of other grains a characteristic of radioanomalous hydrocarbons the occurrence of the nodules is dependent upon an appropriate plutonic source for the thorium but given this constraint they are important evidence for hydrocarbon migration pathways

differences in the depositional environment of basal zechstein in southwest poland implication for base metal mineralization abstract base metal enrichment in the permian basal zechstein sediments occurs in two major areas in southwest poland the north sudetic syncline and the fore sudetic monocline two profiles of kupferschiefer and adjacent limestones from the konrad mine and from the rudna mine were studied by petrographic and geochemical methods in order to recognize similarities and differences in the comparative depositional environment of both areas in the north sudetic syncline basal zechstein was deposited in a shallow marine environment under slightly oxidizing sedimentary conditions it is composed of 1 2m thick mergelkalk which might be the equivalent of werrakalk ca1 in the fore sudetic monocline the basal zechstein is a black shale the so called kupferschiefer t1 with a thickness of 0 2 0 5 m microscopical investigations have shown that a substantial contribution of higher continental plant material is observed only in the north sudetic syncline because of its location near the zechstein sea shore pyrite is present in small amounts only in the fore sudetic monocline apart from the former shoreline of the zechstein sea the organic matter is preferentially composed of degraded algae due to its deposition under deeper anoxic bottom waters abundant pyrite is also present differences in the chemical composition of the respective kerogens are reflected in the results obtained from rock eval analyses hydrogen indices hi are significantly higher in the t1 section of the profile from the rudna mine in comparison to the basal zechstein of the konrad mine profile a depletion of hydrogen is only observed in the highly mineralized section and in rote faule of the konrad mine this indicates that hydrogen equivalents from organic matter participated in metal sulfide precipitation by thermochemical sulfate reduction tsr this is further confirmed by the occurrence of pyrobitumen saddle dolomite and calcite spars in contrast in the mineralized section of the rudna mine profile a depletion of hydrogen is not observed pyrobitumen is missing and saddle dolomite and calcite spars are very rare instead abundant pyrite originating from bacterial sulfate reduction bsr could have been the source of reduced sulfur species available for base metal precipitation after deposition of the sediment pyrite replacement the results allow one to conclude that in both areas base metals were precipitated from ascending solutions due to the interaction with the reducing zechstein barrier several observations argue for a post depositional mineralization process at a temperature of less than 130 c in both areas

truncation and translation of appalachian promontories mid paleozoic strike slip tectonics and basin initiation accreted terranes of the appalachian iapetan and peri gondwanan realms display structural trends that are mainly concordant with promontories and embayments in the laurentian margin indicating that during accretion the shape of the continental margin acted as a template around which accreted terranes were molded in north carolina and new foundland post accretion transcurrent motion appears to be recorded by displaced outboard portions of promontories no longer concordant with those in laurentia a bend in structural trends confined to the peri gondwanan realm at the north carolina south carolina state line is interpreted to represent the dextrally displaced outboard portion of the virginia promontory in newfoundland the hermitage flexure is interpreted as a dextrally displaced laurentian promontory that originated along strike to the northeast in both places promontories were truncated and dextrally translated for 220 250 km by a devonian mississippian orogen parallel transcurrent system which may well have extended for the length of the eastern laurentian margin south of the nearby st lawrence promontory extreme thinning of appalachian crust beneath the maritimes basin is consistent with extension at a releasing stepover estimates of extension are consistent with those obtained from promontory offsets

stress variability and brittle tectonic structures the problem of stress variability both in space and time during brittle deformation of rocks is faced in this note several possible causes of the temporal and spatial variations of the stress tensor are reviewed and discussed a genetic partitioning of the stress tensor is proposed showing that any stress field within a crustal volume can be seen as the sum of relatively simple stress tensors associated to specific genetic components the genetic components discussed in this note are the gravitational the tectonic the fluid the thermal and the diagenetic one each genetic component is a function of several parameters but for all of them the possible important role played by the variable time is emphasised according to numerous researches based on theoretical and experimental grounds brittle deformation in a rock mass occurs when some critical conditions are reached starting from initial equilibrium conditions and leading to even different stress conditions as a consequence of failure field examples are presented and data from literature are discussed to exhibit evidences from complex tectonic structures and to argue about small and large scale spatial variations as well as about short and long term temporal variations of the stress trajectories and of the stress magnitudes that continuously occur during a brittle deformational event the relationships between local and temporal stress variations and what is commonly defined the regional stress field are discussed adding recommendations for future researches

laurentian palaeostress trajectories and ephemeral fracture permeability cambrian eriboll formation sandstones west of the moine thrust zone nw scotland abstract cambrian eriboll formation sandstones of the ardvreck group that crop out west of the moine thrust zone contain joints and quartz filled or quartz lined fractures that resemble cemented joints of the fractures containing quartz five sets strike north nw to wnw ne west and north according to crosscutting relations this is a progression from the oldest to the youngest set sets include opening mode microfractures partly visible in transmitted light as fluid inclusion planes and sharply defined as microveins using sem based cathodoluminescence cl dating the oldest north striking set using inferred quartz accumulation rates fluid inclusions and burial history suggests that these fractures mark a palaeozoic east west least horizontal stress trajectory in laurentia the youngest two sets of porous fractures are associated with faults that cut and postdate the moine thrust zone data indicate that at depth in basins pervasive fracture systems arising from discrete loading events are ephemeral owing to fracture porosity destruction by cementation

diagenetic separation of cadmium and manganese in suboxic continental margin sediments abstract the vertical distribution of cd differs from that of mn in sediment cores taken from the continental margins of the arctic and atlantic oceans the oxic surface sediment is depleted in cd and enriched in mn whereas the subsurface sediment is enriched in cd and depleted in mn in some cores the distributions of solid phase and dissolved mn are offset the porewater profiles indicate that mn is being precipitated relatively deep in the sediment whereas the solid phase distributions indicate that mn has been precipitated very close to the sediment surface in the recent past at one deep site located near the base of the continental slope 3000 m the offset may be caused by a relatively recent decrease in ocean productivity a corresponding decrease in the organic carbon flux to the sediment and a subsequent migration of the redox boundary deeper into the sediment however at a site where the upper sediment layers have accumulated during the last few decades this explanation cannot account for the offset distributions we propose that a fluctuating input of organic matter to the sediment on seasonal or decadal timescales causes the position of the redox boundary to fluctuate the fluctuating redox boundary pumps dissolved mn upward and concentrates it as mn oxide in a distinct layer at the upper limit of the redox excursion at the same time it pumps cd downward and concentrates it in a distinct layer at the lower limit of the redox excursion the net result of a fluctuating redox boundary is to increase the spatial separation of cd and mn during the early diagenesis of suboxic sediments

clausthalite pbse and tiemannite hgse from the type locality new observations and implications for metallogenesis in the harz mountains germany abstract clausthalite and tiemannite from the type locality clausthal in the harz mountains germany have virtually gone undocumented since their discovery in the nineteenth century the minerals and their selenide assemblages are here documented in historical samples from the konigin charlotte mine in the former clausthal pb zn ag mining district clausthalite and tiemannite are the main selenide components naumannite is generally subordinate whereas klockmannite and eskebornite are accessory minerals the absence of inversion lamellae in naumannite constrains the formation temperature to 87 sr 86 sr values of 0 70914 and 0 71133 for two samples of tiemannite aggregates containing celestine anhydrite inclusions the clausthal selenide assemblages postdated the main sulfide bearing polymetallic vein style mineralisation of the harz mountains

accumulation of copper in the permian kupferschiefer a result of post depositional redox reactions abstract within the central european zechstein basin the permian kupferschiefer has been deposited under anoxic conditions in most parts of the basin the metal content does not exceed values commonly observed in black shales however in areas near to the zechstein sea shore which are simultaneously related to rift zones a significant base metal enrichment is observed organic geochemical analyses of the copper mineralized sections in the kupferschiefer from southwest poland show that significant changes in the composition of organic matter are associated with the metal enrichment processes porphyrins commonly abundant constituents of the shale have been decomposed by oxidizing fluids additionally aliphatic hydrocarbons have been largely removed from the bitumen and alkylated aromatic systems were affected by side chain degradation this particular type of alteration is explained by ascending oxidizing solutions which transported high amounts of base metals from lower permian red beds into the kupferschiefer horizon acting as a geochemical trap the metal precipitation is suggested to be a result of thermochemical sulphide production with organic matter acting as hydrogen source in areas such as the lower rhine basin in the bottom section of the kupferschiefer the base metals lead and zinc as well as barium have been accumulated from basinal carboniferous formation waters copper enrichment is not observed because potential source rocks are missing in this area however the observed compositional changes of the organic matter do not point towards thermochemical redox processes

loading paths to joint propagation during a tectonic cycle an example from the appalachian plateau u s a abstract based on the timing of joint propagation during the history of burial lithification deformation and denudation of clastic rocks within sedimentary basins four types of joints may be distinguished tectonic hydraulic unloading and release tectonic and hydraulic joints form at depth prior to uplift in response to abnormal fluid pressures whereas unloading and release joints form near the surface in response to thermal elastic contraction accompanying erosion and uplift tectonic joints are distinguished from hydraulic joints in that tectonic compaction is a mechanism for achieving abnormal pore pressures leading to the propagation of the former whereas compaction by overburden loading leads to the abnormal pore pressures in the latter case the orientation of unloading joints is controlled by either a residual or contemporary tectonic stress whereas the orientation of release joints is controlled by a rock fabric examples of some of these joints are found within the devonian catskill delta of the appalachian plateau new york during the alleghanian orogeny tectonic joints cross fold joints formed under abnormal pore pressure as indicated by the observation that joints propagated in the siltstones before they developed in shales and by the cross cutting relationships of folds cleavage and joints this sequence is compatible with oil company hydraulic fracture data which show that the least principal stress within sandstone layers is less than that in the intercalated shale layers plumose structures indicate that the joints within siltstones propagated as discontinuous rupture events each of which affected less than a meter of bed length the discontinuous rupturing is compatible with models for natural hydraulic fracturing release joints strike joints post date the alleghanian orogeny as indicated by abutting relationships within the deeper parts of the devonian clastic section unloading joints are orthogonal to the contemporary tectonic stress field

spatial arrangement of faults and opening mode fractures spatial arrangement is a fundamental characteristic of fracture arrays the pattern of fault and opening mode fracture positions in space defines structural heterogeneity and anisotropy in a rock volume governs how faults and fractures affect fluid flow and impacts our understanding of the initiation propagation and interactions during the formation of fracture patterns this special issue highlights recent progress with respect to characterizing and understanding the spatial arrangements of fault and fracture patterns providing examples over a wide range of scales and structural settings five papers describe new methods and improvements of existing techniques to quantify spatial arrangement one study unravels the time evolution of opening mode fracture spatial arrangement which are data needed to compare natural patterns with progressive fracture growth in kinematic and mechanical models three papers investigate the role of evolving diagenesis in localizing fractures by mechanical stratigraphy and nine discuss opening mode fracture spatial arrangement two papers show the relevance of complex cluster patterns to unconventional reservoirs through examples of fractures in tight gas sandstone horizontal wells and a study of fracture arrangement in shale four papers demonstrate the roles of folds in fracture localization and the development spatial patterns one paper models along fault friction and fluid pressure and their effects on fault related fracture arrangement contributions address deformation band patterns in carbonate rocks and fault size and arrangement above a detachment fault three papers describe fault and fracture arrangements in basement terrains and three document fracture patterns in shale this collection of papers points toward improvement in field methods continuing improvements in computer based data analysis and creation of synthetic fracture patterns and opportunities for further understanding fault and fracture attributes in the subsurface through coupled spatial size and pattern analysis

production of 210pb from a slochteren sandstone gas reservoir abstract recently precipitates of metallic pb and galena in gas production facilities have been reported to contain 210 pb in the north sea area u bearing kupferschiefer or carboniferous coal measures have been suggested as a possible source of 210 pb through coproduction of formation water with natural gas 210 pb may enter production facilities together with non radioactive pb and precipitate as metallic pb or galena in this study bituminous sandstones with up to 2 8 wt organic c from a 210 pb producing permian slochteren formation gas reservoir have been found to contain up to 330 ppm u the sandstones show a complex diagenetic history during which migrating oil was trapped in secondary pores continuing enlargement of pore space and the wetting characteristics of the reservoir fluids lead to a preferred distribution of oil rims around quartz grains creating fluid filled voids between the grains syngenetic precipitation of finely grained u oxide occurred along the bitumen fluid boundaries u pb chemical age dating of u oxide grains provides an age of 246 ma for the influx of the oil and the close association of abundant anhydrite with the bitumen impregnations points to a zechstein source for both bitumen and u one of the bituminous sandstones shows a marked depletion of 210 pb with respect to 238 u and 226 ra probably caused by the production of natural gas from the reservoir production started at the end of the 1960s and induced fluid flow throughout the reservoir this enabled transport of 222 rn and its decay product 210 pb away from the u oxide grains the observed u concentrations and permeabilities make the bituminous sandstones in this reservoir probably a more important source of 210 pb than the overlying kupferschiefer or underlying carboniferous coal measures

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

organic carbon sulphur and iron in recent semi euxinic sediments of kau bay indonesia kau bay island of halmahera eastern indonesia is a 470 m deep basin separated from the pacific ocean by a sill that is at present only 40 m below sea level during weichselian time the sea level dropped below the depth of the sill and freshwater sediments were deposited these sediments are rich in organic matter corg 2 6 wt with terrigenous isotope characteristics 13corg 28 to 30 and are also rich in sulphur s 4 wt this sulphur enrichment is interpreted to be a late diagenetic feature related to diffusion of dissolved sulphate and sulphide from the marine sediments into the freshwater sediments the sulphur in these sediments has a 34s value of 15 the overlying holocene sediments consist of marine muds deposited in alternating low oxygen and h2s bearing bottom waters the marine sediments are also rich in organic matter corg 2 6 wt but of mixed terrigenous and marine origin 13c 25 to 19 moreover the sulphur content of these holocene sediments is lower s 1 2 wt and isotopically lighter 34s 20 in addition to pyrite large amounts of acid volatile sulphur avs compounds accumulate in kau bay the reactive iron content of the sediment limits the amount of iron that is sulphidized while the supply of oxidants controls the limited conversion of avs to pyrite total and reactive iron contents are strongly correlated with the amount of terrigenous organic matter as a consequence of their common provenance and depositional histories the marine sediments in kau bay show no simple relation between organic carbon and sulphur

two brine model of the genesis of strata bound zechstein deposits kupferschiefer type poland these kupferschiefer deposits were probably formed as a result of a mixing of two brines the upper cold brine ucb is an unmineralized brine rich in na ca cl and so4 with a ph 7 and originating from evaporites overlying the metal bearing zechstein rocks the lower hot brine lhb rich in mg k cl so4 and co3 with a ph 7 formed in sediments in the central part of the zechstein basin at a depth of 7 000 m this brine was subjected to heating and upward convection toward the fore sudetic monocline along the bottom of the z1 carbonates during its migration it caused albitization serpentinization and leaching of the primary metal deposits in rocks underlying the zechstein becoming enriched in heavy metals the mineralization process being a result of the mixing of the two brines ucb and lhb and catalytic oxidation of the organic matter of the black shale were initiated at shallow depths in the area of the fore sudetic monocline the boundary of the two brines generally overlapped the strike of the black shale

interpreting rock eval pyrolysis data using graphs of pyrolizable hydrocarbons vs total organic carbon kerogen the major organic component of sedimentary rocks is commonly analyzed by rock eval pyrolysis plotting the data on a graph of s 2 vs total organic carbon toc and determining the regression equation is the best method for determining the true average hydrogen index and measuring the adsorption of hydrocarbon by the rock matrix such a plot also indicates the type of kerogen present and avoids the problem of increasing hydrogen index with total organic carbon content with the s 2 vs toc diagram the organic component of different suites of samples may be compared and their petroleum generation potentials established as an example the diagrams are used to evaluate the sedimentary environments and petroleum potential of the paleogene evaporitic sediments of the mulhouse basin alsace france

a multistage origin for kupferschiefer mineralization new re os age determinations on mineralized material from the polish kupferschiefer elucidate the timing of mineralization and thus the likely mechanisms of ore deposition three mineralization parageneses were analysed a chalcocite as pore space filling in sandstone b disseminated cu mo mineralization in shale and c massive bedded copper sulphides the resulting ages fall into two ranges 245 2 1 6 264 7 1 8 ma and 162 3 0 8 184 3 2 2 ma these results substantiate previous age determinations although no upper triassic ages were found in this study some of the younger ages for the mineralization could represent alteration and recrystallization of existing sulphides the results confirm that mineralization took place in several stages from soon after kupferschiefer sediment deposition in the upper permian and for at least 100 m y after until at least the cretaceous the genesis of the mineralization can be explained by the episodic release of hydrothermal fluids from the subsiding adjacent southern permian sedimentary basin although the relative importance of each successive mineralizing event for introducing additional metals is as yet unknown

organic geochemistry depositional history and hydrocarbon generation modelling of the upper permian kupferschiefer and zechstein limestone strata in south west poland abstract the upper permian zechstein limestone carbonates in the south western part of the polish zechstein basin contain small quantities of organic matter usually less than 0 1 wt toc and have poor hydrocarbon potential in contrast the kupferschiefer shales have excellent hydrocarbon potential with toc as high as 10 8 wt predominantly algal type ii kerogen generally thermal maturity of the organic matter is 0 6 0 9 vitrinite reflectance while locally is as high as 1 45 the kimmerian and laramian tectonic events significantly influenced the regional burial and thermal history the main subsidence of the kupferschiefer zechstein limestone complex took place during the late permian late triassic period with additional burial during the jurassic and late cretaceous hydrocarbon generation from the kupferschiefer source rocks occurred from middle triassic to late jurassic times reaching maximum rates during the jurassic the cretaceous subsidence had only a minor influence on the maturity and transformation of organic matter expulsion started between late triassic in the western part of the study area and early jurassic in the eastern part then ceased by the late jurassic early cretaceous erosion the total amount of generated and expelled hydrocarbons from source rocks was small because their thickness was limited therefore kupferschiefer shales cannot be considered as source rocks for liquid hydrocarbons but may be a potential source for gas accumulated in the zechstein limestone and rotliegend reservoirs

georadiochemical evidence to weathering of mining residues of the mansfeld mining district germany mining heaps are used as archives for the investigation of weathering processes aim of this work was to investigate the different weathering behavior of heap materials derived from kupferschiefer mining with respect to environmental hazard for this purpose kupferschiefer and slag material of two heaps of different age were examined regarding to the radionuclide distribution and geochemical composition by measuring of the local dose rate performing digital autoradiography and gamma spectrometry the radiological load of the heaps and the heap materials was determined the geochemical characterization of the samples was performed by xrf icp oes and icp ms the results show a clear higher radionuclide load of the younger slag heap a depletion of chalcophile and lithophile elements in the older slag was determined apart from a homogeneous radionuclide distribution considerable radionuclide enrichments in fossil fragments could be proven the results reveal a different weathering behavior of slag material in comparison to the kupferschiefer depending on the chemical binding of the elements on organic and inorganic species natural organic matter as well as apatite in kupferschiefer act as retention barrier for some metals

the occurrences of the rare earth elements and the platinum group elements in relation to base metal zoning in the vicinity of rote faule in the kupferschiefer of poland abstract the concentrations of the lanthanide rare earth elements ree and pt group elements pge were measured in the kupferschiefer from the polish zechstein basin at and in proximity to the rote faule near the lubin mining district the rote faule is a zone of post depositional oxidation characterized by the presence of extensive amounts of fe iii oxides replacing syn sedimentary framboidal pyrite outward from the rote faule the remainder of the kupferschiefer is composed of cu and pb zn mineralized shale surrounding the rote faule and a non mineralized pyritic black shale in the central basin the leading hypothesis explaining the high concentrations of pge and ree in the kupferschiefer states that pge ree and the associated base metals were mobilized by oxidizing cl brines which migrated outward from the rote faule into the reduced kupferschiefer according to available thermodynamic data pge were in all likelihood present as chloro complexes in these oxidizing brines as geologically realistic concentrations of pt pd and au could be transported as chloro complexes the eh of these brines decreased as they migrated further from the rote faule and into the kupferschiefer base metals and pge were precipitated in the order of their decreased solubility in these brines as a result the concentrations of least soluble pge pt are highest in the rote faule and in the transition zone adjacent to the rote faule e g pt 202 537 ppb while the concentrations of the more soluble metals in these brines ag cu pb and re are highest in the reduced mineralized kupferschiefer the sources of the pge and ree are enigmatic it is likely that the metals were derived either from the underlying rotliegendes sandstones and volcanics the variscan basement rocks or the kupferschiefer shale whose metals were mobilized by saline oxidizing fluids released during intra continental rifting in the triassic period

late paleozoic strike slip faults in maritime canada and their role in the reconfiguration of the northern appalachian orogen major late paleozoic faults many with documented strike slip motion have dissected the ordovician devonian appalachian orogen in the maritime provinces of atlantic canada activity alternated between east west faults minas trend and ne sw faults appalachian trend nw se faults canso trend were probably conjugate to minas trend faults major dextral movement on faults with appalachian trend in total between 200 and 300 km began in the late devonian this movement initiated the maritimes basin in a transtensional environment at a releasing bend formed around a promontory in the laurentian margin and thinned the crust accounting for the major subsidence of the basin appalachian trend strike slip continued in the mississippian but was accompanied by major movement on e w minas trend faults culminating around the mississippian pennsylvanian boundary juxtaposing the meguma and avalon terranes of the appalachians close to their present day configuration however strike slip continued during the pennsylvanian permian interval resulting in transpressional deformation that reactivated and inverted earlier extensional faults a final major episode of transtension mainly sinistral occurred during the mesozoic opening of the atlantic ocean restoration of movements on these faults amounting to several hundred kilometers of slip explains anomalies in the present day distribution of terranes amalgamated during early paleozoic appalachian tectonism in the restored geometry the nashoba and ellsworth terranes of ganderia are adjacent to one another and the meguma terrane lies clearly outboard of avalonia a restored post acadian paleogeography not the present day geometry of the orogen should be used as a basis for reconstructions of its earlier paleozoic history

variations in organic geochemistry of anoxic oxic black shale carbonate sequences in the pennsylvanian of the midcontinent u s a abstract two cores containing thin organic rich phosphatic black shale members the excello and little osage shale and transitional lithologies from pennsylvanian cyclothems of southeast kansas and northeast oklahoma were characterized by geochemical and organic petrographic methods by very detailed sampling geochemical analyses included organic carbon determination rock eval pyrolysis bitumen extraction and chromatographic separation into saturated aromatic and nonhydrocarbon fractions gas chromatography of saturated hydrocarbons carbon isotope analysis of coexisting saturated and aromatic fractions and whole rock v and ni analyses organic petrography included maceral identification on polished whole rock fragments and vitrinite reflection and thermal alteration index tai determinations of kerogen concetrates the analytical results demonstrate large and systematic variations in geochemical properties within the black shale units in both cases an abrupt increase in toc 20 25 level and hi 400 level at the initiation of phosphatic black shale deposition is followed by a gradual decline to values of less than 1 toc and 100 hi organic constituents include both liptinitic algal derived and humic terrestrial components variations in their relative amounts control the nature and quality of the organic profile of the little osage shale level of anoxia varied within this sequence and influenced several geochemical parameters pr ph ratios decrease nonhydrocarbons increase relative to hydrocarbons saturated hydrocarbons decline relative to aromatics carbon isotopic composition of coexisting saturated and aromatic hydrocarbons converge and v and ni and the v ni v ratio increase with increased anoxia eustatic rise of sea level and rapid marine transgression over the continental craton with consequent flooding of adjacent extensive brackish marine peat swamps and the resultant influx of a large supply of nutrients and humic detritus appear to be the key geologic control of black shale deposition

manganese fluxes from mississippi delta sediments abstract massive sediment deposition on the mississippi river delta establishes reducing conditions sufficient to bring about mn dissolution in the top millimeters of sediment as a result significant fluxes of dissolved mn pass from the delta sediments to the overlying water column this process is examined by study of chemical partitioning of mn in river particulates and delta sediments and from interstitial water chemistry remobilized mn is actively transported away from the delta area with aluminosilicate detritus thereby providing excess mn to the deep gulf of mexico at the expense of the delta sediments

stratiform copper deposits hosted by low energy sediments i timing of sulfide precipitation an hypothesis published interpretations on the timing of copper and copper iron sulfide deposition in stratiform copper deposits hosted by low energy sediments range from those postulating deposition during sedimentation to those postulating deposition later in the diagenetic history of the host sediments with most favoring deposition during diagenesis interpretations of sulfide precipitation during diagenesis of the host sediments commonly favor a sulfide replacement of biogenic pyrite and in some instances replacement of anhydrite as well a qualitative reexamination was made of published data on 1 sulfur isotopes sulfide textures and sulfide nonsulfide mineral relationships in stratiform copper deposits hosted by low energy sediments and on 2 timing of bacterial sulfate reduction timing of pyrite formation and timing of authigenic mineral formation in modern analogues of host sediments to ore the reexamination is permissive of the hypothesis that chalcocite but not necessarily copper iron sulfides in stratiform copper deposits was precipitated within 50 cm of the sediment surface and that most precipitated within a few centimeters of the surface as a result of bacterial sulfate reduction the reexamination reveals that evidence for a pyrite replacement origin of chalcocite is based upon equivocal interpretations of sulfide textures textures displayed by most bornite chalcopyrite and digenite can be interpreted to indicate an origin by replacement of preexisting pyrite chalcocite composite grains limited porosity and permeability data on modern analogues of the host sediments and on clays are compatible with the hypothesis the porosity and permeability data and published models of compacting shale and sandstone sequences indicate that flow of copper transporting water was probably along rather than across the host rock bedding

geochemical and isotopic composition of organic matter in the kupferschiefer of the polish zechstein basin relation to maturity and base metal mineralization vs the present depth of the kupferschiefer soluble organic matter som yields and relative proportions of saturated and aromatic hydrocarbons of the som provide evidence for an oxidative alteration of organic matter in highly mineralized kupferschiefer samples near the rote faule zones this is confirmed by differences in the composition of the saturated and aromatic hydrocarbon fractions of the soluble organic matter saturated hydrocarbons from rote faule samples are dominated by short chain n alkanes and higher abundances of pristane and phytane relative to heptadecane n c17 and octadecane n c18 respectively compared with samples more distant to the rote faule zone compositional changes of the aromatic hydrocarbon fractions with decreasing distance to that zone are characterized by the occurrence of polycyclic aromatic hydrocarbons and elevated ratios of phenanthrene to methylphenanthrenes that are attributed to demethylation reactions and resulted in a decrease of the methylphenanthrene index mpi 1 kupferschiefer samples from the barren zone of the polish basin do not show these alteration patterns the observed variations in organic matter composition with burial depth are consistent with changes due to increasing thermal maturation maturity assessment is achieved from mpi 1 and the methyldibenzothiophene ratio mdr from the relationship between the maturity of organic matter in terms of vitrinite reflectance values and depth of the kupferschiefer strata a continuous increase in reflectance of vitrinite is obtained within the polish basin the alteration pattern of organic matter related to base metal mineralization of the kupferschiefer corresponds to changes in the isotopic composition of organic carbon and calcite kerogen within or close to rote faule zone is enriched in 13c caused by the preferential release of isotopically light organic compounds through progressive degradation of organic matter the opposite tendency towards lower 13c and 18o values of calcite provides evidence for isotopic exchange between carbonate and the oxidizing ore bearing solutions and for organic matter remineralization in contrast organic matter and calcite from the kupferschiefer do not show regular trends in 13c with increasing thermal maturation

primary copper sulphides from the kupferschiefer poland finely dispersed primary copper sulphide mineralization from the zones of cu s paragenesis in the zechstein copper bearing shale from the fore sudetic monocline poland was studied it is represented mostly by small spherules and framboids 5 to 10 m in size and framboidal clusters of digenite chalcocite and minor covellite dispersed throughout the whole shale but especially abundant in the organic rich laminae detailed microscopic and chemical microprobe descriptions of this mineralization are given and a comparison with pyrite framboids is presented digenite usually dominates over chalcocite among dispersed mineralization in contrast to that observed in larger diagenetic grains the rarity of copper sulphide framboids in comparison with spherules can probably be explained by the fast process of their homogenization the textures chemistry and some different features from pyrite framboids suggest that the copper sulphides in fe poor zones of the kupferschiefer are primary precipitates the results of the study suggest that the beginning and probably the main stage of the ore mineralization process took place during the sedimentation and or early diagenesis of the kupferschiefer