bismuth selenides from st andreasberg germany an oxidised five element style of mineralisation and its relation to post variscan vein type deposits of central europe carbonate veinlets at roter bar a former underground mine in the polymetallic st andreasberg vein district of the harz mountains germany host selenide minerals that are characterised as bi ag bearing clausthalite pbse tiemannite hgse guanajuatite bi2se3 and a number of selenides of bi zn cu ag and pd an unnamed bi pb ag selenide species with some hg and cu ideally bi4pb3ag2se10 is reported here specular hematite is disseminated within the clausthalite at the marginal zones of which other selenide minerals are located the occurrence of bohdanowiczite agbise2 and umangite cu3se2 constrains the formation temperature to 120 c and the selenide hematite assemblage plus barite in the carbonate gangue identifies highly oxidised conditions selenide assemblages of pb bi ag with and without co and ni occur in many parts of the variscan basement of central europe harz erzgebirge schwarzwald and bohemian massif and represent a high oxidation variety of five element ag as bi co ni veins

calcretes at sequence boundaries in upper carboniferous cyclothems of the sydney basin atlantic canada abstract nodular and associated groundwater calcretes in coal bearing cyclothems of the sydney basin mark the boundary between underlying marginal marine and overlying alluvial deposits they are inferred to represent lowstand surfaces sequence boundaries the host sediments include both sand siltstones and palustrine limestones microfabrics of calcretes with detrital hosts show evidence of replacement displacement and shrinkage alpha fabrics suggesting that the calcretes formed under relatively arid conditions in contrast microfabrics of nodular calcretes with limestone hosts exhibit predominantly beta fabrics with root induced brecciation and subordinate shrinkage fabrics the calcretes and host limestones are inferred to have formed in topographic lows thick alluvial sediments with red calcic vertisols overlie the calcretes and formed within the transgressive systems tract under conditions of abundant sediment supply coals and associated hydromorphic palaeosols lie near the transgressive maximum and in the highstand systems tract the presence of calcareous palaeosols on lowstand surfaces suggests that the lowstands were times of relative climatic aridity

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

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

permian to early triassic magnetostratigraphy from the central european basin in poland implications on regional and worldwide correlations abstract permian early triassic rocks sampled in 15 outcrops 93 hand samples and 11 unoriented boreholes 630 hand samples from the polish part of the central european basin were studied paleomagnetically in spite of extensive remagnetization affecting 50 of samples from the boreholes a magnetic polarity sequence was compiled the polarity pattern is not only common for many sections from the investigated area but also convergent with the global synthetic magnetostratigraphic scale the lower rotliegend early permian rocks contain a reversed polarity record while the upper rotliegend late permian early triassic sediments are characterized by mixed polarity magnetization within the buntsandstein part of that mixed megazone 14 magnetic zones were found buntsandstein sedimentation started with a normal polarity zone which may be compared with that of early griesbachian defined in several places in the world the polarity record noted in the middle buntsandstein sediments could indicate significant stratigraphic gaps or condensations near the middle buntsandstein and rot boundary the comparison of the upper buntsandstein polarity with the early middle triassic magnetostratigraphic data from other basins suggests that the majority or even all the rot sediments should be included in the anisian

vegetation zones and diagnostic pollen profiles of a coastal peat swamp bocas del toro panama abstract a survey of the dominant vegetative cover of a large domed coastal swamp near changuinola in the province of bocas del toro panama has been undertaken as an initial step in reconstructing the holocene history of peat accumulation on this coast seven phasic communities of peat forming vegetation are defined and mapped 1 rhizophora mangle mangrove swamp 2 mixed back mangrove swamp 3 raphia taedigera palm swamp 4 mixed forest swamp 5 campnosperma panamensis forest swamp 6 sawgrass stunted forest swamp 7 myrica cyrilla bog plain pollen extracted from surface peat samples and collected from dominant vegetation at representative sites is used to prepare a pollen profile of each phasic community these profiles are then compared to pollen distribution in 2 peat cores one from the deep central part of the deposit and the second from a site near the marine margin in order to construct a history by floral succession of the 4000 year evolution of the deposit the changuinola mire originated as freshwater palm and hardwood forest swamps that developed in close proximity to both the changuinola river mouth probably behind a barrier bar and freshwater lagoon system adjacent to a low energy mangrove dominated bay the early swamp was likely drained to the southeast by brackish blackwater creeks much as it is today and formerly extended considerably farther in the direction of almirante bay the palm swamp was succeeded by hardwood forest swamp dominated by a very limited number of specialized species only one of which campnosperma panamensis is prone to forming monospecific stands increasing accumulation of woody peat promoted by the everwet climate impeded drainage of the mire leading to doming increased oligotrophy and establishment of bog plain conditions in a manner similar to that described by the anderson model of succession in the coastal swamps of malaysia and indonesia development of the changuinola mire did not require the initial mangrove phase which is common to the peat swamps of southeast asia as the palm raphia taedigera is able to colonise and institute peat accumulation in a variety of freshwater and brackish environments

cyclothem digital correlation and biostratigraphy across the global moscovian kasimovian gzhelian stage boundary interval middle upper pennsylvanian in north america and eastern europe the long standing difficulty of correlating pennsylvanian strata among provincial faunal regions is resolved by effecting digital correlation of major glacial eustatic cyclothems that represent high stands when certain species achieved more global distribution than usual in the late moscovian early gzhelian late desmoinesian early virgilian succession in the midcontinent united states several major cyclothems are correlated by both conodont species in common and cyclothem scale with cyclothems in russia moscow basin and ukraine donets basin and the remaining cyclothems fit into the framework by position and scale in this way the suggested event marker for the global kasimovian gzhelian stage boundary first appearance of idiognathodus simulator is supported while possible event markers for the moscovian kasimovian boundary await further evaluation

re os age of non mineralized black shale from the kupferschiefer poland and implications for metal enrichment six samples of non mineralized black shale from a kupferschiefer section in the northern part of the polish zechstein basin zdrada ig 8 drill hole 1026 16 1026 90 m were studied for re os isotopes and selected major and trace elements these black shales averaging 5 82 wt corg and 1 69 wt stot display very low base metal values up to 106 ppb cu 792 ppb pb and 144 ppb zn and have abundances of 64 1376 ppb re and 0 37 1 25 ppb os with a 187os 188os ratio of 6 95 22 5 the regression of all re os data yields an age of 247 20 ma which is within the range of uncertainties of previous rb sr and k ar geochronological studies the scatter in the re os data can be explained in terms of fluctuations in sedimentary conditions i e restricted basin with terrestrial influence

stratigraphic model for glacial eustatic pennsylvanian cyclothems in highstand nearshore detrital regimes lower distal positions on gently sloping shelves ramps affected by pennsylvanian glacial eustatic sea level fluctuation display classic marine transgressive regressive cyclothems which are separated by exposure surfaces or by shallow marine to thin terrestrial beds deposited at lowstand in contrast higher shelf proximal positions display marginal marine units and coastal plain coal beds deposited at marine highstand and separated by thicker terrestrial units both marine and terrestrial strata deposited in high shelf positions underwent significant fluvial incision and valley formation during long stands of lower sea level resulting in discontinuous erosional remnants and subsequent localized terrestrial deposition on irregular leached and eroded surfaces examples from the appalachian illinois and sydney basins display features such as erosional disconformities with rotated slumps buried hilltops preserving erosional remnants of marine units colluvially reduced landscape relief and buried

the magnetization of clay rich rocks in sedimentary basins low temperature experimental formation of magnetic carriers in natural samples abstract rocks are often magnetically altered during burial thus providing a useful method to study their thermo chemical history in order to improve the understanding of burial diagenetic magnetization we experimentally synthesized magnetite in natural samples lower jurassic argillites from the paris basin were heated to 150 c under a confined atmosphere of argon when a magnetic field was applied during the heating a chemical remanent magnetization was acquired rock magnetism studies reveal that most of the newly formed magnetic carriers were magnetite using anhysteretic remanent magnetization as a measure of the quantity of magnetite an increase of up to 150 after heating was observed ferrimagnetic iron sulphide and hematite are observed to have formed in samples composed of less than 3 calcite and new magnetite is sometimes completely absent in samples containing less than 0 5 calcite hysteresis measurements suggest that the new magnetite is in the pseudo single domain state scanning electron microscope studies indicate that the new magnetic carriers are associated with pre existing pyrite the magnetic transformations during the experiments involved a fluid which reacted with iron bearing and sulfur bearing minerals in ways depending on local redox conditions this study shows that magnetite can be produced in argillaceous sediments at the normal temperatures and pressures found in sedimentary basins without any external supply from long range fluid flow

the role of the kupferschiefer in the formation of hydrothermal base metal mineralization in the spessart ore district germany insight from detailed sulfur isotope studies the spessart district sw germany located at the southwestern margin of the permian kupferschiefer basin in central europe hosts abundant stratabound and structurally controlled base metal mineralization the mineralization styles identified are 1 stratabound cu pb zn ag ores in zechstein sedimentary rocks 2 structurally controlled cu as ag ores in zechstein sedimentary rocks 3 crosscutting co ni bi as and cu fe as veins 4 stratabound metasomatic fe mn carbonate ores in zechstein dolomite 5 barren barite veins and 6 fe mn as veins in permian rhyolites building on previous work that involved mineralogical textural and chemical characterization of the major mineralization types we have performed a comprehensive sulfur isotope study that applied both conventional and novel laser ablation multi collector inductively coupled plasma mass spectrometry techniques the 34s values of sulfide minerals from the different ore types are consistently negative and highly variable in the range between 44 5 and 3 9 whereas the 34s values of barite are all positive in the range between 4 7 and 18 9 remarkably stratabound and structurally controlled mineralization in zechstein sedimentary rocks has the least negative 34s values whereas vein type deposits have consistently more negative 34s values the observed pattern of sulfide 34s values can be best interpreted in terms of fluid mixing at the basement cover interface hydrothermal fluids originating from the crystalline basement migrated upward along subvertical fault zones and were periodically injected into groundwaters that were flowing in the post variscan sedimentary cover these groundwaters had interacted with the zechstein sedimentary rocks resulting in fluids characterized by elevated concentrations of reduced sulfur with negative 34s values and alkaline ph repeated mixing between both chemically contrasting fluids caused rapid and efficient precipitation of sulfide ore minerals in hydrothermal veins with highly variable but distinctly negative 34s values

the southern rhine graben a new view of the initial phase one of the puzzling features of the southern end of the rhine graben is the dinkelberg tabular jura block on the eastern shoulder of the graben it is dissected by a large number of faults the most notable ones forming a field of narrow little grabens and half grabens whose bordering faults converge at the level of the middle triassic evaporites which points to decollement at that horizon the little grabens were traditionally considered to be of oligocene age coeval with the main taphrogenesis of the rhine graben two hypotheses were offered for their formation one ascribing them to extension on the extrados of large basement folds the other to gravity sliding on paleoslopes recent field work uncovered overwhelming evidence for an eocene age of the little grabens the time of the initial phase of rhine graben formation at that time there were neither large basement folds nor paleoslopes of any significance and therefore the two hypotheses offered until now do not work however the map view pattern of the field of faults offers a somewhat unusual way out of the dilemma this pattern is most prominently displayed in the dinkelberg area north of the rhine there a lane of narrow decollement grabens with a mean nne strike is confined within the nw striking dinkelberg graben which is much wider and rooted in the basement it is also very shallow with a subsidence on the order of 100 m the lane of decollement grabens forms a dextral en echelon pattern with respect to the dinkelberg graben suggesting stretching of the post evaporite sequence above a basement essentially extended by strike slip this model though not as clearly expressed is also compatible with the data in the rest of the dinkelberg tabular jura block it also fits surprisingly well a theoretical model by withjack and scheiner 1982 that predicts a dominance of strike slip in the marginal area of a system consisting of extension superimposed on doming

reos and s isotopic constraints on the origins of two mineralization events at the tangdan sedimentary rock hosted stratiform cu deposit sw china abstract the tangdan stratiform cu deposit in the kangdian region of south china is hosted in sedimentary rocks of the late paleoproterozoic to early mesoproterozoic dongchuan group orebodies mainly occur in dolostone and black shale above a thick sequence of hematitic sandstone and siltstone mineralization consists mainly of bedding parallel stratiform ores with minor amounts of discordant vein type ores both stratiform and vein type ores are composed of bornite and chalcopyrite with minor chalcocite and digenite associated with gangue minerals including ankerite dolomite calcite and quartz cu sulfides from vein type ores contain 122 293 ppb re much higher than those of stratiform ores 0 6 14 ppb re they have highly radiogenic os with re os model ages ranging from 1413 to 1457 ma and a weighted mean re os model age of 1432 19 ma 2 mswd 0 30 which is within uncertainty in agreement with isochron ages of 1401 30 ma 2 mswd 0 67 and 1397 71 ma 2 mswd 0 22 using 187 re 188 os versus 187 os 188 os and 187 re versus 187 os regression respectively in contrast sulfides from stratiform ores did not yield meaningful model ages due to the extremely low concentrations of re and radiogenic os however early studies have shown that the stratiform ores were likely formed at 1700 ma during the diagenesis of the host strata sulfides from the vein type ores have 34 s values ranging from 15 to 8 significantly lower than those of stratiform ores 3 to 10 suggesting that organic matter may have been involved in the formation of the vein type ores contrasting re os and s isotopes suggest that the two types of ores at the tangdan deposit were likely formed from different ore forming fluids we propose that stratiform ores were precipitated from basinal fluids during the early evolution of the rift basin whereas the vein type ores were formed due to a much younger thermal event during which hydrothermal fluids interacted with overlying black shale to account for the high re and negative 34 s values this study demonstrates that re os isotopes of sulfides can be used to study the origin of hydrothermal system

paleoclimate controls on late paleozoic sedimentation and peat formation in the central appalachian basin u s a abstract in the central appalachian basin at least two major climate changes affected sedimentation during the late paleozoic stratigraphically these two changes are indicated by the distribution of coal beds the variation in coal quality and the variation in rock lithologies in latest mississippian or earliest pennsylvanian time the climate changed from dry seasonal tropical to ever wet equable tropical the equable climate prevailed into the middle pennsylvanian influencing the morphology and geochemistry in peat forming environments many of the peat deposits which formed under the equable climate were probably domed raised bogs low concentrations of dissolved solids in peat formation water resulted in low buffering capacity organic acids caused acidic ph another climate change occurred in late middle pennsylvanian time when evapopation periodically exceeded rainfall resulting in an increase of both dissolved solids and ph 4 to 7 in surface and near surface water throughout the remainder of the pennsylvanian the surfaces of peat deposits were probably planar not domed water in peat forming and other depositional environments became more nearly neutral the coal beds derived from these peats are highly variable in both ash and sulfur contents drier or more seasonal climates are also indicated by sequences of 1 calcareous sandstone and shale 2 nonmarine limestone that shows shallow water and subaerial exposure features and 3 calcareous paleosols that have caliche characteristics our data and observations indicate that physical depositional environment models for the origin of coal do not adequately explain variations in mineral matter content and composition in commercial quality coal beds in the central appalachian basin stratigraphic variation in mineral matter in coal beds and in syngenetic and early diagenetic minerals in rocks associated with the coal beds appears to be better explained by changes in geochemical conditions of nonmarine sedimentation paleoclimate was a principle control on these geochemical conditions

sea level curve for pennsylvanian eustatic marine transgressive regressive depositional cycles along midcontinent outcrop belt north america at least 55 cycles of marine inundation and withdrawal are recognized in the mid desmoinesian to mid virgilian midcontinent outcrop sequence in north america they range from widespread major cycles classic cyclothems with deep water facies extending across the northern shelf through intermediate cycles persisting as marine horizons across the shelf to minor cycles developed on the lower shelf or as parts of major cycles biostratigraphic differentiation of the cycles should establish interbasinal correlation on a scale fine enough to allow evaluation of differential tectonics and sedimentation sequential groupings of cycles are more irregular than proposed megacyclothems or mesothems but they may be obscured by the distinctness of the major cyclothems estimates of cycle periods range from about 40 to 120 x 10 sup 3 yr for the minor cycles up to about 235 to 400 x 10 sup 3 yr for the major cyclothems the range for all cycles corresponds well to the range of periods of earth s orbital parameters that constitute the milankovitch insolation theory for the pleistocene ice ages and it further supports gondwanan glacial control for the pennsylvanian cycles even though the dominant period of the major pennsylvanian cyclothems is up to four times longer than the dominant 100 000 yr period inmore the pleistocene the shapes of both curves display rapid marine transgression rapid melting of ice caps and slow interrupted regression slow buildup of ice caps which suggest similar linkages between the climatic effects of the orbital parameters and ice cap formation and melting at the two different scales widely separated in time 28 references 3 figures less

7 4 kupferschiefer copper deposits of sw poland lubin sieroszowice district lat 51 35 n long 16 6 e

paleoecological interpretation of a middle pennsylvanian coal bed in the central appalachian basin u s a abstract at least 180 small spore species assignable to 62 miospore genera have been identified from the middle pennsylvanian hernshaw coal bed in southern west virginia and its stratigraphic equivalent the fire clay coal bed in eastern kentucky the established natural affinities of a majority of these miospore taxa indicate that the hernshaw fire clay peat swamp supported a diverse flora consisting of arborescent and herbaceous lycopods ferns tree like and small varities calamities and cordaites four floral groupings are recognized in the hernshaw fire clay coal bed the inferred paleoecology and vertical stratification of each of these four floral groupings is similar in structure to the phasic floral communities found in modern domed peat systems suggesting that the ancient hernshaw fire clay peat swamp was a domed deposit compositional characteristics petrographic make up ash yield and sulfur content associated with the four groupings are consistent with and support this interpretation where uninterrupted by inorganic partings the hernshaw fire clay coal bed commonly contains basal coal layers dominated by lycospora bearing arborescent lycopods with successive increments showing a progression to a more fern and herbaceous lycopod dominant flora in younger layers these observations are corroborated by petrographic analyses which show the bed to be compositionally stratified increments dominated by lycospora have high vitrinite contents in contrast to increments containing increased percentages of fern and herbaceous lycopod affiliated taxa that are enriched in inertinite macerals the volcanic ash fall preserved as the flint clay parting in the hernshaw fire clay coal bed had a considerable effect on the development of the ancient hernshaw fire clay peat swamp besides interrupting peat formation the presence of an inorganic substrate represent a major change in edaphic conditions within the swamp this disruption is demonstrated by a change in palynflora and by the establishment and proliferation of some plant groups notably cordaites and calamites that may have been better adapted to growth on mineral soils these palynologic and petrographic relationships thought to be indicative of a domed peat swamp origin are not confined to the hernshaw fire clay coal bed but appear to be characteristic of many coal beds in the appalachian basin and also of coal beds in other basins

clay mineralogy crystallinity and k ar ages of illites within the polish zechstein basin implications for the age of kupferschiefer mineralization a discussion sir bechtel et al 1999 suggest that the formation of diagenetic illite in the kupferschiefer of the polish zechstein basin was coeval with the mineralizing event the ages estimated for the diagenetic illites are in the range of 190 to 216 ma a middle to late triassic date 240 220 ma for the high grade mineralization in the kupferschiefer was inferred from the remanent magnetization of hematite inside the rote faule zone in southwestern poland and the polar wander paths of europe and russia jowett et al 1987 in conclusions p 271 bechtel et al 1999 stated within limits of error the ages inferred for the diagenetic illites inside the mining district of the polish kupferschiefer 190 216 ma are in agreement with the date of the kupferschiefer mineralization proposed by jowett et al 1987 from paleomagnetic measurements thus paleomagnetic data were used for verification of indirect age determination of the main mineralizing event according to bechtel et

peat accumulating depositional systems of sarawak east malaysia many coal deposits originate in deltaic estuarine and coastal plain settings and a knowledge of interrelationships between the tectonic and depositional elements active at the time of sediment deposition is necessary to formulate basin scale models the prograding coastal depositional systems of sarawak all contain domed peat accumulating environments in which low ash low sulfur peats are being deposited in areas of active clastic siliciclastic sedimentation these depositional systems are as large as 11 400 km2 and individual peat deposits within systems are in excess of 20 m thick and 1000 km2 in area the geographic positions and drainage basin areas of each depositional system are controlled by fault and fold systems although prograding into the same receiving basin individual system geomorphology is variable and ranges from a wave dominated microtidal delta to a wave dominated meso to macro tidal delta coastal plain system to a tide dominated macrotidal estuarine embayment along a 450 km stretch of coastline system variation is a function of sediment supply shelf and embayment geometry wave climate and tidal range these factors which control depositional system geomorphology also control the resulting long axis orientation of the thick domed peat deposits the surface vegetation and internal characteristics of most domed peat deposits however are similar internal characteristics consist of basal high ash high sulfur degraded peats overlain by low ash low sulfur well preserved peats in vertical profile these systems demonstrate variable responses to late pleistocene holocene sea level rise and in these instances the variation is most attributable to local differences in siliciclastic sediment supply which is a function of the drainage basin area

genesis of kupferschiefer cu ag deposits by convective flow of rotliegendes brines during triassic rifting extensive and rich cu ag sulfide mineralization occurs in poland across the contact between the upper permian zechstein restricted marine sequence and the lower permian rotliegende continental volcanic and clastic sequence geologic evidence suggests that the mineralization was formed during late diagenesis when metalliferous brines migrated through the rotliegende leaching metals from the volcanic detritus and up the flanks of basement highs possibly along fracture porosity to the pyritic kupferschiefer and zechstein limestone above thick evaporites in the lower zechstein preclude a vertical flow through model but metal zoning attitudes suggest that the brines overturned where the rotliegende pinched out against the highs and moved laterally along the base of the zechstein toward the basin centers presumably to sink back down into the rotliegende completing a convection cell a middle triassic paleomagnetic age for the metal zoning and kimmerian attitudes of dilatant sulfide veinlets indicate that the mineralizing event coincided with continental rifting associated with the opening of the tethys ocean slow unicellular convection may be commonplace in sandstone basins where small lateral temperature gradients delta t exist but greater velocities are necessary to form large orebodies an anomalous tensional and thermal event such as rifting can increase velocities by increasing permeability slope angle or delta t the paleothermal structure of southwestern poland was determined by modeling the conductive heat flow in 14 one dimensional geologic sections which described the evolution of the basin architecture for 10 m y in the early triassic rifting was simulated by increasing the lower boundary condition from 500 degrees to 1 000 degrees c at 25 km this thermal pulse produced a surprisingly high delta t of 25 degrees c across the lubin ore district solely from differences in thermal conductivities between the basement high 4 2 w m degrees c the sandstone 2 5 w m degrees c and the shale basin center 1 25 w m degrees c unicellular convection patterns would be induced by the lateral boundary conditions of warm basement highs and cold shale centers and by the greater horizontal permeability these cells were 15 to 20 km long 400 m high and subhorizontal a slope angle of 2 degrees and a permeability of 1 d produces a convection velocity of 13 cm yr which with a copper solubility of 1 000 mg kg in 20 to 30 percent ca na cl brines in equilibrium with hematite can form the lubin deposit in less than 6 m y using a fracture permeability of 2 d and a solubility of 300 mg kg the time needed is less than 10 m y the konrad mine can be formed in similar time periods without the continuous recycling of the brine inherent in convective flow 20 times or more the metal solubilities needed to form the lubin deposits by a flow through model would be unreasonably high natural gases likely migrated along with the metalliferous brines and helped convection by creating secondary porosity and increasing the buoyancy of the fluids because the fluids are recirculated and not expelled convection provides a way in which secondary migration of methane and petroleum can occur effectively in solution as well as in separate phases

the so called paleophytic mesophytic transition in equatorial pangea multiple biomes and vegetational tracking of climate change through geological time abstract the paleophytic mesophytic and cenophytic were originally conceptualized as chronostratigraphic intervals not specific floras and were used principally in that way for about 100 years they supposedly reflected massive irreversible biotic changes on land that were thought to have happened about half a geological period prior to the changes in marine faunas that mark the more traditional geological era boundaries the terms were applied initially only to terrestrial rocks from the euramerican portions of equatorial pangea especially parts of central europe where the boundary between the paleophytic and mesophytic the eras of interest here was placed at the top of the german rotliegends more recently the terms have been coopted to describe vegetation types not chronostratigraphic units even to the point where specific linnean ordinal or class level clades evolutionary lineages of plants have been attributed solely to one vegetation type or the other at a global level furthermore the paleophytic mesophytic transition has been recognized in the largely taxonomically distinct vegetation types of temperate as well as the equatorial paleolatitudes the result of this conceptual coopting of terms that already were of questionable value is a blurring of the concepts almost to the point of meaninglessness a reading of the literature indicates confusion in terms of what represents the paleophytic flora vs the mesophytic flora the botanical basis for the floras and the taxonomic scale at which they can be recognized the geographic pattern and temporal correlation of the supposed transition and the evolutionary and ecological significance of the vegetational changes these terms supposedly capture we propose that these terms be completely and utterly abandoned as confusing and worse yet misleading evidence suggests that paleozoic vegetation tracked climate which should not come as a surprise in light of what is known of plant dynamics in the holocene and recent furthermore the evidence for a global paleophytic vs mesophytic vegetation is simply unsubstantiated by the fossil record rather there appears to have been a complex of global species pools reflecting climate at many spatio temporal scales the vegetational changes occurring in the late paleozoic thus can be understood best when examined as spatial temporal changes in biome scale species pools responding to major global climate changes locally and regionally manifested

spatial variability in modern tropical peat deposits from sarawak malaysia and sumatra indonesia analogues for coal petrographic and chemical variability in two tropical low ash domed peat deposits of similar age and physiographic setting but different external morphology were examined as modern analogues for coal both occur in microtidal alluvial to deltaic plain settings support similar arborescent vegetation and have accumulated in the past 5 000 years one deposit is an extremely convex mature done with a surface that rises 10 m above river level the other is a low gradient dome rising only 3 m above river level but with a concave base up to 6 m below both deposits have been eroded by adjacent rivers yet peat in the mature dome has accumulated remote from persistent flooding and exhibits distinctive internal stratigraphy decomposed sapric peat floors the deposits and is overlain by increasingly better preserved woody hemic and a cap of coarse fibrous peat derived from less arborescent vegetation consistent flooding in the low gradient dome has maintained conditions for the accumulation of predominantly woody hemic peat which interfingers with and is overlain by oxidised sapric peat and levee derived clastic sediments peat types in both deposits exhibit distinctive polymodal textures and organo chemical signatures that correspond to botanical input and degree of decay due to the abundance of pre huminite vitrinite macerals in all peat types from these deposits megascopic and microscopic texture is a better discriminator for comparison to ancient coal types it is suggested that the upward vertical sequence of decreasing woodiness and increasing lightness in colour observed in the mature dome might best be compared to sequences observed in tertiary brown coals this typical sequence can be modified or overprinted due to flooding in the burial process

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

stratigraphic distribution of macerals and biomarkers in the donets basin implications for paleoecology paleoclimatology and eustacy abstract more than one hundred and thirty coal seams and coaly layers occur in the donets basin donbas twenty eight 52 samples of them ranging in age from serpukhovian late mississipian to gzhelian late pennsylvanian 33 clastics and three limestones were studied in terms of maceral composition sulphur contents and biomarker distribution diterpanes are used to estimate the contribution of different groups of plants and the height of the water table in the swamp hopanes are a measure of bacterial activity in the peat and steranes indicate the relative input of wood and algae stratigraphic trends in these parameters are discussed in relation to paleoenvironment climatic changes and eustacy a tropical climate prevailed in the donbas from serpukhovian to kasimovian times nevertheless periods with drier and wetter conditions can be distinguished based on maceral and biomarker data relatively dry conditions are observed during serpukhovian and vereian times whereas wetter climates with a maximum of coal deposition occurred during the late bashkirian most of the moscovian and the earliest kasimovian no economic coal seams are hosted in upper kasimovian and gzhelian deposits a result of a change to an arid climate our data also suggest climatic changes during sequences of different order for the second order third order and fourth order sequences relatively dry or wet conditions occurred during coal deposition in the lowstand systems tract an intermediate climate during the transgressive systems tract and the maximum flooding and a wet climate during the highstand systems tract the results for high frequency sequences support the cecil s paleoclimatic model an intermediate paleoclimate during lst sandstone and levee siltstone a wet climate during early tst coal and a dry climate during late tst limestone mfs claystone and hst deltaic siltstone coals deposited during maximum flooding periods are more enriched in c27 steranes derived from algae and contain lower proportions of c29 steranes derived from the wood of higher plants

pennsylvanian tropical rain forests responded to glacial interglacial rhythms pennsylvanian tropical rain forests flourished during an icehouse climate mode although it is well established that milankovitch band glacial interglacial rhythms caused marked synchronous changes in pennsylvanian tropical climate and sea level little is known of vegetation response to orbital forcing this knowledge gap has now been addressed through sequence stratigraphic analysis of megafloral and palynofloral assemblages within the westphalian d cantabrian sydney mines formation of eastern canada this succession was deposited in a low accommodation setting where sequences can be attributed confidently to glacio eustasy results show that long lived low diversity peat mires dominated by lycopsids were initiated during deglaciation events but were mostly drowned by rising sea level at maximum interglacial conditions only upland coniferopsid forests survived flooding without significant disturbance mid to late interglacial phases witnessed delta plain progradation and establishment of high diversity mineral substrate rain forests containing lycopsids sphenopsids pteridosperms cordaites and tree ferns renewed glaciation resulted in sea level fall paleovalley incision and the onset of climatic aridity glacial vegetation was dominated by cordaites pteridosperms and tree ferns hydrophilic lycopsids and sphenopsids survived in paleovalley refugia findings clearly demonstrate the dynamic nature of pennsylvanian tropical ecosystems and are timely given current debates about the impact of quaternary glacial interglacial rhythms on the biogeography of tropical rain forest

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

consistency investigation vertical gravity estimation and inversion of airborne gravity gradient data a case study from northern sweden for airborne gravity gradient data it is a challenge to distinguish between high frequency intrinsic and dynamically produced noise caused by the aircraft and small scale effects from shallow dens

early cretaceous mineralizing activity in the st andreasberg ore district southwest harz federal republic of germany in the st andreasberg ore district southwest harz at some time between the main and subsequent stages of mineralization sensu wilke 1952 potassium feldspar adularia was formed hydrothermally based on isotopic dating rb sr 40ar 39ar the formation of this mineral is ascribed to the early cretaceous thus part of the st andreasberg mineralization is proved to have been formed in the late mesozoic the mineralization process forming feldspar does not coincide with magmatic phases of the area

the composition of brines in the early diagenetic mineralization of the permian kupferschiefer in germany the kupferschiefer is an approximately 0 5 m thick black marly shale of lower zechstein age in germany if one includes some of its footwall and hanging wall it contains 300 mt cu 800 mt zn and 300 mt pb the regional pattern of metal distribution demonstrates its relationship to variscan and permian tectonic structures faults and the topographic relief of the basement apparently controlled the uprise and lateral migration of reducing and slightly acid hot brines from deeper crustal levels to supply the metals for the mineralization of the proto kupferschiefer deep fluids are mainly richer in zn than pb and richer in pb than cu mixing of such slightly acid fluids with slightly alkaline formation waters seawater caused a gradient in ph from about three to eight and in sulfide concentration most of the sulfide came from dissolved pyrite which was very light in sulfur isotopes this gradient controlled the sequential precipitation of bornite chalcopyrite chalcocite galena and sphalerite which is observed in a lateral and vertical zoning of these sulfides the fluids experienced a fractionation of the metals during migration over meter to kilometer distances from the tectonically controlled vents within the unconsolidated proto kupferschiefer close to the vents the sulfide deposits attained concentrations up to 2 zn pb cu the migration of the metals over large distances took place in unconsolidated sediment thus the major mineralization of the kupferschiefer has to be classed as an early diagenetic process

comparison of drier to wetter interval estuarine roof facies in the eastern and western interior coal basins usa abstract many of the carboniferous coals in the eastern interior of the us are associated with siliciclastic roof facies that were deposited within a fluvio estuarine transition these facies include a variety of rhythmites some of which exhibit tidal cycles drier interval coals westphalian b c stephanian tend to be more laterally restricted and more commonly are associated with paleovalleys conversely wetter interval coals westphalian d are very widespread and are not restricted to paleovalleys throughout the lake carboniferous wet paleoclimates associated with these coals lead to valley incision during sea level lowstand when large tropical rivers downcut older sediments deposited during previous sea level highstands during subsequent rise of sea level these fluvial valleys were flooded and converted to estuaries where tidal ranges and sedimentation rates were significantly amplified based on modern analogs and interpretation of many examples of carboniferous tidal rhythmites the localized depositional rates in these settings are exceptionally high the estuaries became sediment sinks trapping sediment that is pumped in from both fluvial and marine sources as a result sedimentation readily keeps pace with rising baselevel extensive intertidal flats and shallow subtidal flats are created and prograde over the valley confined mires thick tidal cycles and upright trees some with attached foliage record rapid burial of mires this model is supported with examples of roof facies from the westphalian b c of the eastern interior basin and the stephanian of the western interior basin in these areas facies within each cycle range from well developed extensive paleosols and coals to widespread marine shales or limestones variations in both sea level and climate resulted in a complex history of valley fill during which coals could be developed at any time except during widespread flooding minable low sulfur and low ash coals occur but the coals are relatively thin and discontinuous conversely the westphalian d coals are very widespread and significant peat accumulations were not confined to paleovalleys nonetheless the lowest sulfur coals are related to rapid deposition of roof facies that occurred within the paleovalley whereas high sulfur coals were formed in areas of lower sedimentation rate of roof facies that occurred beyond the confines of the paleovalley

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

relationship between petrographic and chemical properties and coal seam geometry hance seam breathitt formation southeastern kentucky the upper hance coal seam in southeastern kentucy was used as a template to examine the spatial distribution of ash yield sulfur content and petrographic constituents relative to the geometry of the deposit geometric characteristics include thinning and splitting of the two main benches leaders and riders analytical data showed the thick non split portions of the coal body to be low in ash and sulfur as well as vitrinite content whereas the thinned and split margins were higher in ash sulfur and vitrinite content these relationships suggest that thick non split portions of the upper hance peat accumulated in areas isolated from detrital influx while thinner marginal peat was subject to intermittent flooding from adjacent channels marginal peat was derived from larger trees which flourished at the mire s edge in the presence of adequate nutrients whereas only stunted vegetation subsisting in the nutrient depleted center contributed to interior peat accumulation ponds formed on the sparsely vegetated mature surface of the bog s interior the petrographic and chemical character of the hance coal body is analogous to ombrogenous domed peats which characteristically contain higher concentrations of inorganics at the periphery of the deposit

provenance of cretaceous clastics in the subhercynian basin constraints to exhumation of the harz mountains and timing of inversion tectonics in central europe the harz mountains and the adjacent subhercynian cretaceous basin figure as the most prominent surface representative for late cretaceous inversion structures in central europe facies depositional architecture and provenance of the basin fill reflect mechanisms and timing of the exhumation of the harz from hauterivian to early santonian there is no evidence for detrital input from the nearby harz area sediments are mature quartzarenites derived from paleozoic basement rocks and or recycled permian to mesozoic sedimentary rocks this situation changed drastically in middle to late santonian when freshly exhumed and eroded mesozoic sedimentary cover rocks of the harz were delivered into the basin feldspar and lithoclasts reflect erosion of triassic and in places jurassic to turonian strata apatite and garnet in heavy mineral spectra are derived from largely unweathered lower triassic buntsandstein as indicated by apatite and garnet chemistry in early campanian paleozoic lithoclasts indicate erosion cutting down into the basement of the harz simultaneous strong decrease of feldspar garnet and apatite suggest an almost complete removal of the 2 3 km thick mesozoic cover of the harz within only 2 4 myr this translates into an exhumation rate of approximately 1 mm a consistent with apatite fission track data from granitoid rocks of the harz mountains

sedimentology of the changuinola peat deposit organic and clastic sedimentary response to punctuated coastal subsidence an extensive peat deposit on the caribbean coast near changuinola panama has developed in an area subject to periodic earthquake driven coseismic subsidence thick low ash low sulfur peat is accumulating immediately behind an aggrading and prograding barrier system and adjacent to a flood prone sediment laden river measurements of changes in local sea level as a result of a recent april 1991 earthquake reveal 30 50 cm of subsidence greatest at the southeastern extent of the study area where the peat surface is submerged to a depth of 3 m beneath the shallow waters of almirante bay transgression is proceeding from southeast to northwest parallel to the trend of the coast and the long axes of both the peat deposit and the major sand bodies in the eastern part of the deposit the effects of sea level rise are evident in the degree of humification mineral matter and sulfur content of mangrove and back mangove peats offshore and immediately adjacent to the marine margin and in peats associated with brackish tidal channels that drain the deposit however most of the deposit shows no indications of marine influence even though 40 of the peat is below present sea level the western section of the deposit has evolved from low lying palm swamps which originated in swales on the barrier bar into an oligotrophic bog plain with a water table elevated 6 75 m above sea level as the mire evolved transitions in vegetation resulted in transitions in peat types highly humified forest swamp and palm swamp peats underlie and surround well preserved fibric sedge peats and create a partial hydrological bounding surface that restricts subsurface drainage from the central bog the high water table and elevated topography of the mire and the low permeability and erosion resistance of the dense woody peat effectively insulate most of the deposit from both clastic influx and the extensive intrusion of rising marine waters it is evident that thick peat and hence coal deposits can accumulate due to tectonically driven punctuated subsidence without leaving a record of high clastic input within the peat even immediately adjacent to environments of active clastic deposition

late paleoproterozoic to early mesoproterozoic tangdan sedimentary rock hosted strata bound copper deposit yunnan province southwest china sedimentary rock hosted strata bound copper deposits are widespread in the kangdian region of the central yunnan and southern sichuan provinces southwest china the deposits occur within weakly metamorphosed rocks of the late paleoproterozoic to early mesoproterozoic dongchuan group and are spatially associated with discordant breccia bodies that are interpreted as having formed from salt diapirs the tangdan deposit the largest in the region consists of stratiform and discordant orebodies predominantly hosted in dolostones immediately above hematitic sandstones and siltstones and in black shales above the dolostones host rocks for the deposit display a complex paragenetic sequence of alteration and mineralization early sodic alteration resulted in the growth of both albite and ferroan dolomite later potassic alteration resulted in the precipitation of potassium feldspar and locally biotite in argillaceous layers sulfide mineralization was temporally and spatially associated with silicification that postdated both sodic and potassic alteration textures suggest that silicification may have preferentially affected evaporite minerals in the dolostones copper sulfides form bedding parallel disseminations veinlets and to a lesser extent stockworks copper sulfides are dominated by chalcopyrite with lesser bornite and chalcocite hypogene chalcopyrite and bornite from the tangdan deposit have 34s values that range from 12 7 to 9 3 and cluster between 3 to 5 the values suggest derivation from mesoproterozoic marine sulfates the dolostone host rocks have relatively homogeneous c and o isotope values ranging from 0 2 to 1 3 13cv pdb and from 19 1 to 22 4 18ov snow carbonate minerals in quartz sulfide veins display both a trend toward lighter oxygen isotope values and a trend to significantly lighter carbon isotope values the light carbon isotope values suggest involvement of organic carbon in the mineralizing process alteration and mineralization at tangdan probably occurred via interaction of oxidized saline brines derived from the underlying red bed sequence with partially to wholly lithified dolostones sulfide precipitation was likely due to both redox reactions and mineralizing fluid ph changes resulting from dolomite and sulfate dissolution the styles of alteration and mineralization at the tangdan deposit are similar to those observed in the central african copperbelt particularly the dolostone hosted orebodies in the mines series of the democratic republic of congo

the kupferschiefer cu ag ore deposits in poland a re appraisal of the evidence of their origin and presentation of a new genetic model the kupferschiefer stratiform copper deposits in central europe have long been considered a classic example of syngenetic mineralization however metal zoning and host rock relationships determined during exploration around the recently discovered lubin district orebodies in southwest poland suggest that the ore may instead be late diagenetic the mineralization occurs as thin extensive blankets of sulphides in the pyritic organic rich basal units of the late permian zechstein restricted marine sequence and in the eolian weissliegendes sandstone at the top of the early permian rotliegendes continental rift sequence of bimodal volcanic rocks and redbeds it is directly underlain and controlled by irregular oval zones of rote faule rf a barren oxidized and reddened portion of the normally dark grey pyritic basal zechstein rocks in plan view the metals occur as successive belts enriched in copper silver lead and zinc which developed laterally from and encircle the rf zones the ore transgres

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

geochemistry of autochthonous and hypautochthonous siderite dolomite coal balls foord seam bolsovian upper carboniferous nova scotia canada abstract the 11 13 m thick foord seam in the fault bounded stellarton basin nova scotia is the thickest seam from the euramerican floral province known to contain coal balls in addition to the first discovery of autochthonous coal balls in the foord seam nova scotia its shale parting also contains hypautochthonous coal balls with histologically preserved plant structures the coal ball discovery helps fill a stratigraphic gap in coal ball occurrences in the upper carboniferous bolsovian of euramerica the autochthonous and hypautochthonous coal balls have a similar mineralogical composition and are composed of siderite 81 100 dolomite ankerite 0 19 minor quartz and illite and trace amounts of calcite similar is also their permineralizing mineralogy which consists of dolomite ankerite and siderite their low pyrite content and carbonate mineralogy and nonmarine origin differentiates the foord seam coal balls from other euramerican coal ball occurrences a preliminary geochemical model which is based on oxygen and carbon isotopic data indicates that siderite in both the autochthonous and hypautochthonous coal balls is of very early diagenetic nonmarine origin from 13 c enriched bicarbonate derived from bacterial methanogenesis of organic matter

palynological correlation of major pennsylvanian middle and upper carboniferous chronostratigraphic boundaries in the illinois and other coal basins

cordaiteans in paleotropical wetlands an ecological re evaluation abstract cordaiteans in cordaite dominated permineralized peat from pennsylvanian coals in iowa have been reconstructed as mangroves using root anatomy peat taphonomy and geochemical data macrofloral palynofloral and conodont biostratigraphy indicate that these peats come from the latest atokan blackoak coal and earliest desmoinesian cliffland coal mid moscovian both in the kalo formation thus their depositional setting can be used to evaluate the mangrove hypothesis in recent mires thick mangrove peats have accumulated in tropical to subtropical carbonate systems in contrast thick tropical freshwater peats have accumulated in siliclastic systems kalo formation coals which we interpret as freshwater deposits formed in siliciclastic depositional settings similar to those of modern tropical freshwater peat and to other pennsylvanian coals in north america interpreted as freshwater deposits in the late atokan and earliest desmoinesian mid moscovian cordaiteans and tree ferns predominated in the western interior and illinois basins lycopsids and cordaiteans predominated in the appalachian and donets basins the scarcity of lycopsid only mires in north america during the late atokan earliest desmoinesian mid moscovian suggests drier climates than during the mid to late desmoinesian late moscovian rather than indicating mangrove swamps cordaite dominated peat may indicate climates with a low rain season although most plants in cordaite dominated peat probably grew in freshwater coastal mires in climate zones with seasons of low rain may harbor mangrove taxa the changuinola swamp of panama a modern peat accumulating wetland that has a low rain season is a possible analog of ancient cordaite dominated mires in changuinola most plants require freshwater however mangroves sustained by salt water influx into the swamp grow along the seaward edge and along blackwater creeks the low rain season hypothesis has implications for understanding rainfall amount and continuity during pennsylvanian cyclothem deposition the floral succession in diverse cordaite coals from cordaiteans to tree ferns to lycopsids suggests increasingly wet climate during coal accumulation the position of these coals immediately above the sequence boundary suggests humid climate during early glacial melting for these cyclothems

a mid triassic paleomagnetic age of the kupferschiefer mineralization in poland based on a revised apparent polar wander path for europe and russia extensive mineralization occurs in southwest poland as zoned blankets of cu ag pb zn sulphides in the kupferschiefer and zechstein limestone across the base of the late permian zechstein restricted marine sequence and in the weissliegendes sandstone at the top of the early permian rotliegendes continental volcanic and siliciclastic sequence the rote faule rf zone an oxidized hematitic equivalent of the normally pyritic basal zechstein directly underlies the copper ore and is part of the metal zoning although the origin has generally been considered to be syngenetic geologic controls of the rf ore systems in poland suggest a late diagenetic origin by converting metalliferous brines migrating through the rotliegendes clastic redbeds up along basement highs oxidizing the pyritic kupferschiefer to form the rf and precipitating base and precious metals on the reduced side of this oxidation reduction front a paleomagnetic study of the ore zone in five mines in poland the rf zone in three mines and of the barren pyritic basal zechstein from outcrops and quarries in poland germany and england was undertaken to determine the absolute age of the mineralization in the barren pyritic rocks and the copper sulphide ore thermal demagnetization and vector subtraction revealed an unstable low temperature first remanence component 76 9 n 12 2 e a63 1 6 parallel to the ambient field and a second higher temperature component 82 6 n 145 9 e a63 1 9 which could be miocene 10 20 ma or less likely cretaceous 110 ma or jurassic 180 ma this second component is erased at 350 400 c and is thought to be carried by a product of weathering after alpine age uplift and erosion no primary magnetization could be isolated in the copper or pyritic zones the rf hematite however contained a very stable third reversed component 49 0 n 157 2 e a63 2 2 which was revealed typically between 500 and 620 c and is considered to represent a secondary chemical remanent magnetization acquired during the mineralizing process in order to date the isolated magnetic components carboniferous to neogene apparent polar wander apw paths for europe and russia were constructed using paleopole catalogs mean paleopoles every 10 ma from 350 to 0 ma with a63 circles of confidence were calculated as running averages using overlapping 20 and 30 ma time intervals the rf pole corresponding to the third remanence component coincides extremely well with a middle triassic age of 240 ma on the 20 ma apw path and a late triassic age of 230 ma on the 30 ma apw path statistical analysis yields upper and lower age limits of 250 and 220 ma this triassic paleomagnetic age supports the proposed late diagenetic origin of the kupferschiefer ore deposits and suggests that the rf ore systems were formed immediately after triassic continental rifting associated with the opening of the tethys ocean to the south a likely source of the thermal anomaly necessary to initiate adequate convective velocities within the rotliegendes clastic basins

magnitude of climate variability during middle pliocene warmth a palaeoclimate modelling study abstract the nature and magnitude of climatic variability during the period of middle pliocene warmth ca 3 29 2 97 ma is poorly understood we present a suite of palaeoclimate modelling experiments incorporating an advanced atmospheric general circulation model gcm coupled to a q flux ocean model for 3 29 3 12 and 2 97 ma bp astronomical solutions for the periods in question were derived from the berger and loutre bl2 astronomical solution boundary conditions excluding sea surface temperatures ssts which were predicted by the slab ocean model were provided from the usgs prism2 2 2 digital data set the model results indicate that little annual variation 0 5 c in ssts relative to a control experiment occurred during the middle pliocene in response to the altered orbital configurations annual surface air temperatures also displayed little variation seasonally surface air temperatures displayed a trend of cooler temperatures during december january and february and warmer temperatures during june july and august this pattern is consistent with altered seasonality resulting from the prescribed orbital configurations precipitation changes follow the seasonal trend observed for surface air temperature compared to present day surface wind strength and wind stress over the north atlantic north pacific and southern ocean remained greater in each of the pliocene experiments this suggests that wind driven gyral circulation may have been consistently greater during the middle pliocene the trend of climatic variability predicted by the gcm for the middle pliocene accords with geological data however it is unclear if the model correctly simulates the magnitude of the variation this uncertainty is derived from a the relative insensitivity of the gcm to perturbation in the imposed boundary conditions b a lack of detailed time series data concerning changes to terrestrial ice cover and greenhouse gas concentrations for the middle pliocene and c difficulties in representing the effects of climatic history in snap shot gcm experiments

stratigraphic and interregional changes in pennsylvanian coal swamp vegetation environmental inferences abstract quantitative analysis of pennsylvanian coal swamp vegetation provides a means of inferring organization and structure of communities distribution of these communities further provides inferences about environmental factors including paleoclimate our observations are based on in situ structurally preserved peat deposits in coal ball concretions from 32 coal seams in the eastern one half of the united states and from several seams in western europe and on spore assemblages from more than 150 seams there were three times of particularly significant and nearly synchronous vegetational changes in the midcontinent and appalachian coal regions during the pennsylvanian period each was different in kind and magnitude the first marked changes occurred during the early part of the middle pennsylvanian with the fluctuating decline in the high level of lycopod dominance the abundance of cordaites increased there was a rise in the occurrences of the lycopod herbs to form intercalated marshlands and an overall increase in floral diversity changes ensuing from this time also include shifts in dominant species of lycopod trees and a sustained rise in abundance and diversity of tree fern spores the next significant time of change was during the middle part of the middle pennsylvanian representing both a culmination of earlier trends and expansions of cordaites in the midcontinent where there was a maximum change in species without net loss of diversity tree ferns and medullosan pteridosperms attained subdominant levels of abundance and diverse lycopod species dominated except in the atokan desmoinesian transition of the midcontinent the third and sharpest break occurred near the middle late pennsylvanian boundary when extinctionsof the dominant coal swamp lycopods allowed development of tree fern dominance the late pennsylvanian coal swamps apparently were colonized or recolonized mainly by species from outside coal swamps rather than by the survivor populations of the middle pennsylvanian swamps paralleling the changes in floras through the pennsylvanian are changes in preservational aspects of the peat these include a decline in shoot root ratios from approximately 1 to

global time scale and regional stratigraphic reference scales of central and west europe east europe tethys south china and north america as used in the devonian carboniferous permian correlation chart 2003 dcp 2003 the boundaries of the devonian carboniferous and permian stages of the global stratigraphic reference scale abbreviated to global stratigraphic scale gss are described in relation to the biostratigraphic and or lithostratigraphic units of the regional stratigraphic reference scales abbreviated to regional stratigraphic scales rss of central and west europe east europe tethys south china eastern tethys and north america in their type regions the boundaries of gss units rarely coincide with those of homonymous rss units moreover the definitions of some rss units have changed several times over the last decades and subsequent misunderstanding of the stratigraphical significance of these changes has often introduced errors into proposed global correlation charts the stratigraphic framework proposed in our global devonian carboniferous permian correlation chart 2003 dcp 2003 devonian carboniferous permian correlation chart 2003 menning m schneider j w alekseev a s amon e o becker g von bitter p h boardman d r bogoslovskaya m braun a brocke r chernykh v chuvashov b i clayton g dusar m davydov v i dybova jachowicz s forke h c gibling m gilmour e h goretzki j grunt t a hance l heckel p h izokh n g jansen u jin y g jones p kading k ch kerp h kiersnowski h klets a klug ch korn d kossovaya o kotlyar g v kozur h w laveine j p martens th nemyrovska t l nigmadganov a l paech h j peryt t m rohn r roscher m rubidge b schiappa t a schindler e skompski s ueno k utting j vdovenko m v villa e voigt s wahlman g p wardlaw b r warrington g weddige k werneburg r weyer d wilde v winkler prins c f work d m 2004 abschlusskolloquium dfg schwerpunktprogramm 1054 evolution des systems erde wahrend des jungeren palaozoikums im spiegel der sedimentgeochemie abstracts univ erlangen germany 2004 p 43 herein abbreviated to dcp 2003 and cited as dcp 2003 in references is an attempt to reduce these errors the dcp 2003 is the stratigraphic base for project 1054 of the deutsche forschungsgemeinschaft dfg the evolution of the late palaeozoic in the light of sedimentary geochemistry this composite time scale has been carefully balanced as far as data allows to remove unnecessary artificial compression and expansion of time intervals biozonations and depositional events the ages selected in dcp 2003 are markedly different to those in the geologic time scale 1989 gts 1989 harland w b armstrong r l cox a v craig l e smith a g smith d g 1990 a geologic time scale 1989 cambridge univ press cambridge harland w b armstrong r l cox a v craig l e smith a g smith d g 1990 a geologic time scale 1989 cambridge univ press cambridge pp 1 263 and in gradstein and ogg gradstein f m ogg j 1996 a phanerozoic time scale episodes 19 1 2 3 4 insert whereas they are closer to those of the geologic time scale 2004 gts 2004 gradstein f m ogg j g smith a g 2004 a geologic time scale 2004 cambridge univ press cambridge pp 1 589 mostly the ages are rounded to the nearest 0 5 ma in order to avoid estimates of questionable accuracy whereas ages of 0 1 ma in the gts 2004 and their error bars of 0 4 ma to 2 8 ma for the devonian to permian stage boundaries suggest an improved accuracy in contrast in the dcp 2003 questionable ages and positions of stratigraphic boundaries are marked by arrows c 2006 elsevier b v all rights reserved

the changuinola peat deposit of northwestern panama a tropical back barrier peat coal forming environment abstract a large 82 km 2 thick 8 m low ash low sulfur peat deposit has formed on the northwestern coast of panama its low ash and low sulfur contents can be attributed partly to 1 doming 2 the occurrence of a relatively continuous marine blocking beach barrier shoreline feature and 3 leaching of the mineral matter this deposit is roughly rectangular in shape and oriented with its longest axis parallel to the beach barrier shoreline it would produce an economic coal bed that is bright and finely banded in its thickest central region and more coarsely banded at its margins its northwestern margin would be characterized by interfingering of coal with sandstone and siltstone of the changuinola river flood plain whereas its southeastern boundary would be characterized by truncation of the upper part of the seam by marine to brackish shales siltstones and carbonates that were derived from almirante bay total sulfur was found to be very low less than 0 2 dry wt except in a few places in these rare cases nearly all of the sulfur was pyritic and the total sulfur content was anomalously high 14 although the general tendency was for total sulfur to increase wherever the deposit was influenced by marine conditions one case was found where sulfur was high at the base of an inland freshwater peat core which suggests either a hidden marine influence or the need for some new mechanism to explain sulfur enrichment in such an anomalous case differences in inherent fixed carbon contents and calorific values due to changes in peat type and analytical uncertainties tended to mask seamwide trends in these parameters however fixed carbon contents and calorific values showed a slight tendency to increase with depth especially if plotted for single peat types vitrinite reflectance within the hypothetical changuinola coal bed would be expected to increase as follows 1 toward the margins of the deposit 2 toward the bottom and top of the bed and 3 toward stream channels or tidal inlets

the chemical composition of specular hematite from tilkerode harz germany implications for the genesis of hydrothermal hematite and comparison with the quadrilatero ferrifero of minas gerais brazil the black shale hosted selenide vein type deposit at tilkerode eastern harz germany has specular hematite enclosed in clausthalite pbse the specular hematite has ti and v in amounts of up to 1 wt tio2 and 3 wt v2o5 and subordinate but important contents of mo 22 372 ppm and b up to 68 ppm the tilkerode hematite serves as a reference for hydrothermal hematite formed at relatively low temperatures 150 c the composition of the tilkerode hematite is compared with that of two generations of specular hematite from itabirite hosted iron ore deposits in the quadrilatero ferrifero of minas gerais brazil the first generation of specular hematite represents an early tectonic hematitisation of dolomitic itabirite at aguas claras and occurs as fine grained crystals reconnaissance data indicate that the aguas claras hematite is poorer in ti and v relative to the tilkerode hematite but has 5 10 ppm b and 7 11 ppm li the second generation of specular hematite defines the pervasive tectonic foliation of the gongo soco iron ore this hematite has ti contents of up to 2 wt tio2 and subordinate amounts of v 62 367 ppm its b and li concentrations are mostly below 2 ppm b and 1 ppm li the presence of ti and b in the tilkerode hematite can be explained by highly saline b bearing fluids that were capable of mobilising otherwise immobile ti the mo signature of the tilkerode hematite suggests that mo was derived from the host black shale in minas gerais b and li were incorporated into the early tectonic hematite from saline fluids at relatively low temperatures aguas claras and then released during metamorphic hematite growth at higher temperatures as suggested by the foliation defining hematite without b li signature gongo soco

reconstructions of the continents around the north atlantic at about the 60th parallel abstract late carboniferous early tertiary apparent polar wander apw paths 300 40 ma for north america and europe have been tested in various reconstructions these paths demonstrate that the 500 fathom bullard et al fit is excellent from late carboniferous to late triassic times but the continental configuration in northern pangea changed systematically between the late triassic ca 214 ma and the mid jurassic ca 170 ma due to pre drift extension best fit north atlantic reconstructions minimize differences in the late carboniferous early jurassic and late cretaceous tertiary segments of the apw paths but an enigmatic difference exists in the paths for most of the jurassic whereas for the early cretaceous the data from europe are nearly non existent greenland s position is problematic in a bullard et al fit because of a late triassic early jurassic regime of compression 300 km that would be inherently required for the norwegian shelf and the barents sea but which is geologically not defensible we suggest a radically new fit for greenland in between europe and north america in the early mesozoic this fit keeps greenland locked to europe for the late paleozoic early mesozoic and maintains a reconstruction that better complies with the offshore geological history of the norwegian shelf and the barents sea pre drift a24 extension amounted to approximately 450 km on the mid norwegian shelf but with peak extension in the late cretaceous

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

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

world peat occurrence and the seasonality of climate and vegetation abstract the climatic controls on present day peat formation are examined in order to develop a uniformitarian tool for refining paleoclimate studies and to create a retrodictive model for the coals of the geologic record a peat database has been compiled for the world and the resulting patterns are compared with aspects of precipitation and temperature drawn from a gridded data set precipitation continuity through the annual cycle is important for biologic productivity in the terrestrial realm it is expressed in terms of the number of months with average precipitation above 40 mm temperature is limiting at higher latitudes where the potential growing season may be defined by the number of months with mean temperature exceeding 10 c a map predicting the growing season has been constructed from these rainfall and temperature statistics which compares very well with actual vegetation persistence through the year as measured directly from satellite instruments however biologic production will not result in peat accumulation unless groundwater levels are maintained through the growing season our peat prediction map therefore shows the percentage of time that precipitation occurs during the potential growing season present day peat accumulations are well predicted by this map

red bed and basement sourced fluids recorded in hydrothermal mn fe as veins sailauf germany a la icpms fluid inclusion study the hydrothermal mn fe as vein mineralization at sailauf germany hosts a complex sequence of oxide and carbonate minerals that record a protracted fluid history the mineralization is related to a major unconformity that separates permian zechstein sedimentary rocks from underlying variscan crystalline basement the hydrothermal veins contain two principal mineralization stages which are mn oxides associated with calcite and hematite associated with mn calcite the fluid evolution of the hydrothermal system has been reconstructed from fluid inclusion petrography microthermometry and la icpms microanalysis coupled with stable isotope geochemistry of carbonate and oxide minerals the fluid inclusions are high salinity sodic calcic brines and the bulk fluid properties show no major differences between the mn oxide and the hematite stage la icpms analysis of major and trace elements demonstrates that the mineralization formed from chemically distinct fluid pulses characterized by variations in their k li b pb and zn concentrations the fluid that precipitated the mn oxide stage has anomalous pb zn and li b ratios which closely resemble fluids found in fracture fillings in red beds of the permian rotliegend basin by contrast the fluids associated with the hematite stage have pb zn and li b ratios typical of crustal fluids that were derived from interaction with crystalline basement both fluids possess characteristic element ratios including cl br but variable absolute concentrations of most metals this suggests that both fluids were modified by mixing with a common metal depleted brine that had a similar cl br ratio most likely a formation water from the overlying zechstein sedimentary rocks the sailauf mineralization provides insight into the protracted post variscan fluid evolution at the basement cover interface the compositionally anomalous fluid that precipitated the mn oxides is comparable to brines derived from interaction with red beds and likely represents the ore fluid of kupferschiefer type sediment hosted cu deposits conversely the fluid that deposited the hematite mineralization resembles fluids that typically form basement and sediment hosted pb zn deposits

application of the 187re 187os system to black shale geochronometry the decay of 187re to 187os provides a tool for determining depositional ages of black shales re and os concentrations and os isotopic compositions of whole rock samples of the bakken shale a mississippian devonian boundary black shale yield a whole rock isochron with an age of 354 49 ma this age is in agreement with the accepted age of the bakken shale 360 ma the initial 187os186os ratio of the isochron is 6 2 3 3 this value is indistinguishable from the 187os186os ratios observed in modern black sea sediments the concentration of common os in bakken shale samples is strongly correlated with total nitrogen indicating that a large fraction of the os in these samples is associated with a hydrogenous component which overwhelms any os supplied to the sediment in association with detrital material or cosmic dust the dominance of the hydrogenous component imparts a relatively homogeneous initial 187os186os ratio to the sediment at the time of deposition the degree of scatter about the isochron exceeds the degree of scatter expected from either analytical error or from the estimated degree of initial isotopic heterogeneity the pattern of scatter is consistent with postdepositional mobilization of re and or os on a small spatial scale we suggest that this mobilization may be a consequence of petroleum formation and migration in the bakken shale

lead isotope systematics of vein type antimony mineralization rheinisches schiefergebirge germany a case history of complex reaction and remobilization processes mesothermal vein type sb mineralization in the rheinisches schiefergebirge germany is characterized by two different mineralization styles which are 1 extensional quartz stibnite vein systems and 2 cu pb sb sulphosalt assemblages in overprinted pre existing pb zn veins a detailed pb isotope study of 52 representative samples from both mineralization types indicates distinct compositional patterns cu pb sb sulphosalts meneghinite boulangerite bournonite formed by reaction remobilization are characterized by pb isotope compositions 206pb 204pb 18 179 18 223 which are identical to the precursor galena 206pb 204pb 18 168 18 223 the pb isotope composition of sulphosalt minerals in these vein systems was controlled by lead inherited from pre existing galena stibnite and pb sulphosalts zinkenite semseyite plagionite formed in quartz stibnite vein systems display pb isotope ratios 206pb 204pb 18 250 18 354 which are more radiogenic than galenas from variscan pb zn ore veins 206pb 204pb 18 162 18 303 detailed small scale investigation of thrust zones hosting pb zn ores and crosscutting quartz ankerite fissure veins ramsbeck deposit indicates that the pb isotope compositions of recrystallized galena and remobilized phases boulangerite semseyite bournonite are arranged along a linear trend this is interpreted as mixing between primary galena with 206pb 204pb 18 206 and overprinting hydrothermal fluids with a more radiogenic composition 206pb 204pb 18 354 expressed by intermediate compositions 206pb 204pb 18 256 18 334 of newly formed sulphosalts the pb isotope systematics of the vein type sb mineralization is in accordance with a model of pb extraction from similar crustal sources palaeozoic sedimentary sequences at different times

paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks climate is a primary control on sediment flux from continental sources into sedimentary systems in warm climates siliciclastic input is greatest under highly seasonal rainfall nonseasonal conditions favor formation of end member chemical rocks perennially wet climates are conducive to coal formation whereas dry climates produce carbonates and or evaporites stratigraphic repetition of siliciclastic and chemical rocks therefore appears to be related to paleoclimate cycles as well as to transgressive regressive events and tectonics

palynologic petrographic and geochemical characteristics of the manchester coal bed in eastern kentucky the manchester coal bed in eastern kentucky is the stratigraphically lowest coal in kentucky that is both laterally continuous and of consistent mineable thickness the manchester coal bed occurs in the lower part of the breathitt formation in an interval between the underlying corbin sandstone and the overlying betsie shale both of which are also aerially widespread units the manchester is early middle pennsylvanian in age and is equivalent with the middle morrowan of the eastern interior basin and the late westphalian a of western europe increment samples were collected from the western and eastern outcrop and mining areas of the eastern kentucky coal field and were analyzed palynologically petrographically and geochemically to compare and contrast the two areas in the western part of the eastern kentucky coal field the manchester coal bed is uniform in occurrence and composition the bed is consistently 0 61 0 92 m 2 3 ft thick and generally is devoid of inorganic partings palynologically the coal in this area is largely dominated by lycospora the dispersed spore of many of the large lycopsid trees e g lepidodendron and lepidophloios and to a lesser extent granasporites medius representing diaphorodendron and synchysidendron petrographically the coal contains high percentages of vitrinite macerals and correspondingly low percentages of liptinite and inertinite macerals most of the increments from this area studied are generally low in ash yield 5 and sulfur content 10 and occasionally sulfur 1 in the eastern part of the coal field the manchester coal bed is typically thicker 3 ft 1 m but usually occurs as a coal zone with intercalated coal beds and clastic units palynologically the coal in this area contains increased percentages of small lycopsid small seed ferns calamites and cordaites petrographically the coal is higher overall in liptinite and inertinite macerals ash yields in the eastern sample area are generally low 10 an exception being some high ash durain bands overall sulfur contents also are low typically 1 the western samples are interpreted as having formed in a well protected generally flooded mire a consistent water cover would provide a favorable environment for arboreous lycopsid growth and proliferation and also inhibit oxidation of the peat surface thus promoting the formation of a high vitrinite content coal the eastern samples are also interpreted as having formed in a mire that was well protected most of the time giving rise to thick sequences of low ash low sulfur coal intermittent inundation by extra swamp waters carrying sediment in this area resulted in the development of a multiple coal zone i e several peat forming events with intervening clastic deposition in contrast to a single peat forming event in the western area surficial peat exposure was more frequent in the eastern area which allowed for increased microbial degradation of the peat and subsequent formation of inertinite macerals upon conversion to bituminous coal this condition might also accelerate charring of the peat surface by wildfire