organic geochemical proxies of paleoceanographic paleolimnologic and paleoclimatic processes abstract organic matter constitutes a minor fraction of marine and freshwater sediments yet its important contribution to the sedimentary record can be used to reconstruct marine and continental paleoenvironments the organic matter content of sediments is the residue of past biota the amounts and types of organic matter present in sediments consequently reflect environmental conditions that impacted ecosystems at different past times general sources of the organic matter are inferred from bulk properties such as elemental compositions carbon and nitrogen stable isotope ratios rock eval pyrolysis data and organic petrography details of organic matter origins are refined by analyses of biomarker molecular compositions source changes are proxies for fluctuations in sea level oceanic surface currents and continental climates algal paleoproductivity rates are indicated by organic carbon mass accumulation rates and carbon and nitrogen stable isotopic compositions these parameters record past availability of nutrients and therefore are proxies of surface mixing in the oceans and amount of land runoff to lakes sea surface paleotemperatures are recorded by the number of carbon carbon double bonds in lipid biomarkers produced by marine algae larger proportions of the double bonds are proxies for the cooler surface waters that accompanied periods of global glaciation and intervals of enhanced upwelling the 13c and d values of plant organic matter record past concentrations of carbon dioxide in the atmosphere and changes in delivery of atmospheric moisture respectively diagenesis which causes the concentration and composition of organic matter in sedimentary settings to differ from those of the original biologically synthesized materials can bias organic geochemical paleoenvironmental records the magnitude of this potential source of misinformation must always be considered and evaluated comparison of multiple organic geochemical proxies of past conditions helps to compensate for the effects of diagenetic alterations and thereby to improve interpretations of paleoenvironmental change

mineral mapping and ore prospecting using landsat tm and hyperion data wushitala xinjiang northwestern china abstract the southern tianshan area situated in central asia is one of the most important gold belts identified by many world class superlarge and large gold deposits the wushitala area located in the eastern part of southern tianshan xinjiang china has a strong potential for gold and other metallic mineral deposits however no metallic mineral deposit or occurrence has been reported in detail for the wushitala area in the past apparently due to poor exploration this study attempts to map alteration zones and acquire ore prospecting targets in the wushitala area by integrating landsat tm and hyperion data with the aster spectral library mineral spectra the crosta technique and the anomaly overlaying selection method were combined to process four temporal landsat tm data acquired in the same season in different years so as to eliminate the random interference caused false anomalies of alteration minerals iron oxides and hydroxyl bearing minerals and carbonates while retaining the real anomalies the matched filtering method was applied on hyperion data for the detailed identification of hydrothermally altered minerals surrounding the granites in the north the results of hyperion data are spatially consistent with those of landsat tm data furthermore the results of hyperion data show that the alteration minerals associated with the potash feldspar granite are dominated by muscovite and goethite in our field campaign fourteen sites eleven acid intrusion related and three structure associated distributed throughout the study area were inspected all of which proved to be of geological genesis our study led to the discovery of three mineralization sites associated with acid intrusions and structures that were not previously documented due to the extensively distributed acid intrusions and structures along the southern tianshan belt several other gold iron copper mineralized locations could be found with more detailed investigations our mineral prospecting methodology proved effective in the study area and is hereby suggested for application in similar geological settings

geological characteristics and metallogenesis of sawayaerdun gold deposit in southwest tianshan mountains xinjiang the sawayaerdun gold deposit in wuqia county of southwest xinjiang occurs in upper silurian and lower devonian epimetamorphic carbonaceous turbidite with the host rocks being carbonaceous phyllites metasandstone and metasiltstone gold mineralized zones and orebodies are controlled by the brittle ductile shear zone fluid inclusions in the sawayaerdun gold deposit can be divided into two phase vapor liquid h 2o inclusions liquid rich h 2o inclusions vapor rich h 2o inclusions daughter mineral bearing polyphase inclusions and three phase co 2 type inclusions of which two phase vapor liquid h 2o inclusions seem to be the main type the ore forming fluids are of the middle low temperature 78 355 and low middle salinity 2 57 22 10 w nacl eq h 2o nacl co 2 ch 4 system the 34 s values of sulfides associated with gold mineralization range from 3 0 to 2 61 with a mean of 0 07 indicating that sulfur was derived from the mantle or the mantle related magma the 13 c pdb values of dolomite and siderite from the sawayaerdun gold deposit range from 5 4 to 0 6 suggesting that carbon mainly came from the mantle and marine carbonate rocks hydrogen and oxygen isotope studies show that the ore forming fluids were mainly derived from meteoric water with a minor part from magmatic fluids the sawayaerdun gold deposit resembles the muruntau gold deposit in uzbekistan and the kumtor gold deposit in kyrgyzstan in geological setting metallogenic characteristics and ore forming mechanism nevertheless the sawayaerdun gold deposit shows some particularities the ore forming process is characterized by epizonal mineralization and the association of medium low temperature elements such as gold and antimony makes up the most prominent feature changes in physico chemical conditions of ore fluids and fluid compositions water rock exchange and immiscibility of ore fluids played important roles in the ore forming process of the sawayaerdun gold deposit

fungal abundance spike and the permian triassic boundary in the karoo supergroup south africa the most severe mass extinction of marine species and terrestrial vertebrates and plants is associated with the permian triassic boundary 251 ma the extinction interval is also marked by the disappearance of most late permian gymnosperm palynomorphs at a layer containing solely the abundant remains of fungi this fungal spike apparently represents widespread devastation of arboreous vegetation stratigraphic and palynological study of the carlton heights section in the southern karoo basin of south africa revealed a 1 m thick fungal spike zone that occurs simultaneously with the last appearance of typically late permian gymnosperm pollen the plant extinction and fungal spike zone are found above the last occurrence of late permian mammal like reptiles of the dicynodont zone at other karoo sections using the fungal event as a time line in marine and non marine sections allows placement of the marine extinctions and the extinction of terrestrial plants and reptiles within a brief crisis interval of less than about 40 000 years at the end of the permian

positive europium anomaly at the permo triassic boundary spiti india a limonitic layer at the base of the otoceras ophiceras zone in the lalung section in spiti valley shows a significant positive europium anomaly with maximum eu eu 1 9 this layer defines the contact between the earliest griesbachian and the permian productus shale sequence the layer shows a small cerium anomaly having the maximum value of ce la n 1 4 the iridium concentration in this layer at 73 pg g is only marginally above the levels found in the adjacent shales although higher than that found in the overlying limestones another horizon having 114 pg g of ir occurs 70 cm below this limonitic layer in the shale sequence these observations have important implications both for the terrestrial mainly volcanic and extra terrestrial impact hypotheses for the permo triassic transition which are discussed

evidence for a fungal event methane hydrate release and soil erosion at the permian triassic boundary in southern israel abstract the transition between the permian and the triassic systems in israel is evident only in the subsurface two cores from the makhtesh qatan 2 core 9 and avedat 1 core 5 drillholes in which the permian triassic boundary was found marked by a fungal event were sampled at close intervals and analysed for palynological petrographical mineralogical chemical and isotopic properties three palynozones were recorded lueckisporites virkkia zone late permian fungal event and endosporites papillatus zone early triassic the fungul event occurs in a narrow interval of 1 m and contains almost exclusively fungal remains and recycled woody particles the two cores consist of laminated sediments mainly siliciclastic that were deposited in very shallow to restricted marine environments with a minor presence of evaporites and no bioturbation green glauconitic material and framboidal pyrite suggest suboxic conditions even in the shallow waters reddish brown particles and plant fragments derived from nearby soils now outcropping on the northeast side of the dead sea these materials as well as recycled brown glauconitic grains suggest a drop in sea level and intense erosion before sedimentation which was apparently continuous major and trace element compositions including rare earth elements do not exhibit any particular pattern that might be related to the fungul event or to other core intervals the rare earth element patterns are basically normal and their concentration correlates with the clay content reflecting the provenance of the arabo nubian massif and its sedimentary rims iridium results were mostly at the background level and therefore the two distinct anomalous values are inconclusive microspherules mainly of 2 m size and al si composition were observed in a few samples in both cores their origin could not be determined though they are considered to be natural there was no evidence for shocked quartz 13corg excursion exhibits a marked negative shift in both cores just below the fungal event the lowest values 37 and 42 are among the lowest ever recorded near the permian triassic boundary and suggest large scale release of methane hydrates

multiple stage mineralization in the sawayaerdun orogenic gold deposit western tianshan xinjiang constraints from paragenesis empa analyses re os dating of pyrite arsenopyrite and u pb dating of zircon from the host rocks abstract the sawayaerdun deposit located in the southern tianshan orogenic belt in xinjiang nw china is one of many orogenic gold deposits in the central asian orogenic belt caob the deposit is controlled by reverse faults and hosted in highly deformed carbonaceous turbidites that have undergone pyritic arsenopyritic silicification carbonate and sericitic alteration gold occurs mainly in the form of electrum and native gold and is also present in pyrite and arsenopyrite as invisible gold three generations of auriferous pyrite have been recognized through detailed petrographic studies and empa analyses the pyrite with framboidal texture py 0 is disseminated in the host rock and is locally enriched in gold the anhedral pyrite py 1 associated with silicification and quartz veins that experienced strong deformation has an average au content of 0 021 wt the euhedral subhedral pyrite py 2 showing octahedron cube and pyritohedron habits is associated with least deformed quartz veins that are best developed in the main orebodies and has an average au content of 0 023 wt the py 0 is interpreted to have formed contemporaneously with the ore bearing rocks with a maximum depositional age of 355 7 3 ma based on u pb dating of detrital zircons re os isotopic analyses of four py 1 samples yielded an isochron age of 324 4 8 ma and those of five py 2 samples yielded an isochron age of 282 12 ma py 1 is interpreted to have formed in the syn tectonic stage during the collision between the tarim craton and the central tianshan terrane in late carboniferous whereas py 2 was formed in a later mineralization event during the late to post tectonic stage in early permian these study results suggest that multiple stages of gold mineralization have developed in the sawayaerdun deposit and similar mineralization processes may have taken place in other parts of the western tianshan orogen

the terminal paleozoic fungal event evidence of terrestrial ecosystem destabilization and collapse because of its prominent role in global biomass storage land vegetation is the most obvious biota to be investigated for records of dramatic ecologic crisis in earth history there is accumulating evidence that throughout the world sedimentary organic matter preserved in latest permian deposits is characterized by unparalleled abundances of fungal remains irrespective of depositional environment marine lacustrine fluviatile floral provinciality and climatic zonation this fungal event can be considered to reflect excessive dieback of arboreous vegetation effecting destabilization and subsequent collapse of terrestrial ecosystems with concomitant loss of standing biomass such a scenario is in harmony with predictions that the permian triassic ecologic crisis was triggered by the effects of severe changes in atmospheric chemistry arising from the rapid eruption of the siberian traps flood basalts

fossil wood carbon isotope stratigraphy of the non marine wealden group lower cretaceous southern england fossil wood carbon isotope data are presented for the wessex formation a non marine unit within the lower cretaceous valanginian barremian wealden group of the isle of wight and dorset southern england the carbon isotope values have a range 13 c c 26 6 to 19 8 that is consistent with that expected for mesozoic c 3 plants consideration of the isle of wight fossil wood carbon isotope data together with data from dorset allows construction of a composite fossil wood carbon isotope curve for almost the entire wealden group the new carbon isotope curve is in smooth continuity with data previously published from the overlying lagoonal vectis formation and marine lower greensand group of aptian age a tentative correlation with a tethyan reference carbon isotope curve allows the provisional application of stage level chronostratigraphy to the wealden group correlations suggest that the wealden group sediments are dominantly of hauterivian and barremian age and that the valanginian is either condensed or partially missing the carbon isotope data presented indicate that even during times of relative carbon cycle quiescence atmosphere co 2 faithfully tracks the carbon isotopic composition of the oceanic reservoir

methane driven oceanic eruptions and mass extinctions focusing on the permian triassic boundary ca 251 ma i explore the possibility that mass extinction can be caused by an extremely fast explosive release of dissolved methane and other dissolved gases such as carbon dioxide and hydrogen sulfide that accumulated in the oceanic water masses prone to stagnation and anoxia e g in silled basins the mechanism of the explosive release is the same as in the lake nyos disaster of 1986 i e a water column eruption caused by the interplay of buoyancy forces and exsolution of dissolved gas the eruption brings to the surface deep anoxic waters that cause extinctions in the marine realm terrestrial extinctions are caused by explosions and conflagrations that follow the massive release of methane the air methane mixture is explosive at methane concentrations between 5 and 15 and by the eruption triggered floods this scenario accounts well for the available data and may be relevant to other phenomena

permian triassic boundary magnetostratigraphy from the southern alps italy palaeomagnetic investigations of permian triassic boundary sections in the dolomites provided a magnetostratigraphy for the uppermost part of the permian bellerophon formation to the lower triassic werfen formation magnetite was the dominant magnetic component in most of the samples while the presence of hematite was characteristic for the tesero horizon which is regarded as the immediate permian triassic boundary layer the palaeomagnetic results are consistent with earlier studies of permian and triassic sediments and volcanites in the southern alps the mean characteristic remanence directions indicate deposition and remanence acquisition at a shallow northerly palaeolatitude and a counterclockwise rotation a zone of reversed polarity occurs at the top of the permian sequence and a polarity change from reverse to normal polarity shortly above the base of the werfen formation the onset of a tectonically controlled sedimentary cycle marks the beginning of the basal triassic normal polarity zone which corresponds to most of griesbachian time the record of geomagnetic polarity across the permian triassic boundary confirms the apparent continuity as found by sedimentologic biostratigraphic investigations which emphasise a gradual lithic transition with no evidence for a time gap at the boundary

high resolution terrestrial permian triassic eventostratigraphic boundary in western guizhou and eastern yunnan southwestern china the adjoining area of western guizhou and eastern yunnan provinces in southwest china is an ideal place to investigate the feasibility of correlating marine and nonmarine permian triassic boundary ptb sequences as it contains outcrop sections of shallow marine marginal marine or paralic and terrestrial ptb sections all in close geographic proximity this paper documents for the first time multiple stratigraphic data from several well preserved terrestrial ptb sections in the area and attempts to use these data to define locate and correlate the ptb in the area a study of the spores and pollen and vegetation types across the terrestrial ptb sections in the study area suggests three distinct evolutionary stages across the boundary stage 1 xuanwei formation is characterised by late permian or paleozoic type ferns and pteridosperms 85 0 with a few gymnosperms 15 0 stage 2 is marked by an abrupt drop of sporopollen elements of late permian aspects coupled with the appearance of fungal spores and limited early triassic palynomorphs stage 3 top xuanwei formation and kayitou formation is dominated by gymnosperm pollen 58 8 of clearly early triassic aspect although still retaining limited ferns and pteridosperms the three biotic stages seem to well correspond with the changing trend of the 13corg curves from the same sections which is characterized by a sharp drop just before the ptb followed by a short term partial recovery across the boundary and then succeeded by a gradual decline after the ptb in the early triassic combining evidence from eventostratigraphic i e the succession of boundary clay beds biostratigraphic using both macroplants and palynomorphs and chemostratigraphic i e organic carbon isotope excursion signals we propose that a high resolution ptb succession closely correlatable to its marine counterpart at the meishan section in eastern china is recognisable at the terrestrial ptb sections in the western guizhou eastern yunnan area in southwest china

rapid and synchronous collapse of marine and terrestrial ecosystems during the end permian biotic crisis a newly studied permian triassic p tr boundary section in jameson land east greenland contains an abundant and well preserved marine fauna as well as terrestrial palynomorphs for the first time it is possible to compare the biotic crises of the marine and terrestrial realms using the same samples from the same section the sediments record a negative excursion in 13 c carb values of 8 9 and in 13 c org values of 10 11 the presence of the conodont hindeodus parvus combined with the 13 c carb record enables correlation with the proposed global stratotype section at meishan this shows that the greenland section is the most expanded p tr section known collapse of the marine and terrestrial ecosystems took between 10 and 60 k y it took a further few hundred thousand years for the final disappearance of permian floral elements collapse of the terrestrial and marine ecosystems began at the same stratigraphic level and preceded the sharp negative excursion in the 13 c record

ocean stagnation and end permian anoxia ocean stagnation has been invoked to explain the widespread occurrence of organic carbon rich laminated sediments interpreted to have been deposited under anoxic bottom waters at the time of the end permian mass extinction however to a first approximation stagnation would severely reduce the upwelling supply of nutrients to the photic zone reducing productivity moreover it is not obvious that ocean stagnation can be achieved numerical experiments performed with a three dimensional global ocean model linked to a biogeochemical model of phosphate and oxygen cycling indicate that a low equator to pole temperature gradient could have produced weak oceanic circulation and widespread anoxia in the late permian ocean we find that polar warming and tropical cooling of sea surface temperatures cause anoxia throughout the deep ocean as a result of both lower dissolved oxygen in bottom source waters and increased nutrient utilization buildup of quantities of h2s and co2 in the late permian ocean sufficient to directly cause a mass extinction however would have required large increases in the oceanic nutrient inventory

δ13c depth profiles from paleosols across the permian triassic boundary evidence for methane release stable carbon isotopic analyses of organic carbon 13 c in individual paleosol profiles from permian triassic sequences of antarctica reveal systematic isotopic variations with profile depth these variations are in many cases analogous to those in modern soils which are functions of redox conditions soil development and degree and type of microbial decay in modern soils these isotopic depth functions develop independently from vegetation changes c 3 versus c 4 vegetation and can be diagnostic of soil orders this study shows that soil intrinsic functions can be preserved in the 13 c values of paleosols as old as 260 ma and constitute valuable data for paleoecological interpretations a large carbon isotopic offset of as much as 10 in whole paleosol profiles across the permian triassic boundary indicates significant changes in the soil biogeochemistry and the soil atmosphere system early triassic paleosols are distinctive in their extremely low 13 c values to 42 and often show an anomalous 13 c depth distribution compared to both permian paleosols and modern soils highly depleted 13 c values as the ones in early triassic paleosols are suggested to be associated with microbial methane oxidation methanotrophy this hypothesis implies increased methane concentrations in the early triassic soil atmosphere system increased atmospheric methane was probably partly responsible for the global carbon isotopic shift documented in marine and terrestrial sediments across the permian triassic boundary

reworked palynomorphs and their use in the determination of sedimentary cycles the permian triassic sequence in the subsurface of israel was deposited near the margin of the arabian craton which was a major source for both reworked organic and inorganic detritus three major depositional cycles are identified in this sequence each consisting of a transgressive interval and a regressive interval analysis of the stratigraphic variation in the amounts of reworked palynomorphs indicates that they are most abundant in regressive intervals this is considered to be a result of changes in the extent of exposed land which was the source for the reworked palynomorphs or of changes in the transportational regime stratigraphic variation in the abundance of reworked organic detritus may be useful for identifying depositional cycles that are not otherwise evident in the rock record

magnetic properties of k t and e o microspherules origin by combustion abstract magnetic spherules and spheroids are found in association with ir anomalies at the cretaceous tertiary k t boundary and near to the eocene oligocene e o boundary detailed magnetic analyses have been performed on these particles and on bulk k t boundary clay from marine and continental sections coercivity spectra and blocking and curie temperatures of the spheroids and k t boundary clays have been determined and natural remanence and susceptibility measured for the bulk clay and associated strata marine k t boundary clays are strongly magnetic with remanent coercivities similar to those of the spheroids in contrast the continental clays are diamagnetic except for the thin overlying impact layer which contains abundant paramagnetic jarosite along with shocked quartz and feldspar the morphologies mineralogies and magnetic properties of the k t magnetic spheroids are closely analogous to magnetic fly ash spherules this similarity may be related to the presence of carbonaceous soot particles in some marine k t boundary clays and the recent identification of plerospheres and cenospheres in continental boundary clay in contrast tektites and microtektites differ from the k t magnetic spherules in a number of fundamental ways the late eocene particles are magnetically distinct from the k t spheroids both in their coercivity and thermal spectra inaa results on upper cretaceous combustible shales indicate that the anomalous abundances of certain chalcophile and lithophile elements at the k t boundary may be explained in terms of the natural combustion of bituminous sediments

decompressional anatexis in the migmatite core complex of northern dabie orogen eastern china petrological evidence and ti in quartz thermobarometry the voluminous diatexites in the dabie orogen of eastern china indicate spectacular anatexis in the orogen basement before exhumation to shallow depths but determination of the pressure temperature p t conditions for anatexis in the core complex is problematic because of the lack of suitable mineral assemblages in the diatexite and of re equilibrations during the retrograde stages to overcome this problem we studied an amphibolitic migmatite which occurs as a raft in the diatexites of the central dome and has been partially melted at a very low degree in such rocks with low degree of melting the microstructures still reveal the high temperature melting reactions and thus mineral analyses can be used to constrain anatectic p t conditions and interpret the geochemical characteristics of partial melts we demonstrate from petrological evidences that incongruent partial melting of amphibole plagioclase quartz lead to the formation of clinopyroxene and silicate melt trace element analyses of clinopyroxenes confirm that they have been equilibrated with anatectic melts two types of amphiboles can be identified and the amphibole cores have high al2o3 9 0 wt and tio2 1 5 wt contents suggesting a nearly constant temperature of 850 850 c with a pressure varying from 6 to 2 kbar in contrast the rims of some amphibole grains have low al2o3 8 0 wt and tio2 1 2 wt contents indicating temperatures lower than 750 c at low pressures 2 kbar we propose two distinct phases in the tectonic evolution of the migmatite core complex in the northern dabie orogen the early stage is a near isothermal exhumation and the investigated rocks are characterized by a decompression from more than 20 km to 6 km low degree partial melting in the infertile quartz poor amphibolite occurs at low pressure during this exhumation phase the second phase is characterized by a shallow nearly isobaric cooling stage these two tectonic phases are recorded in quartz grains using ti in quartz thermobarometry the quartz in contact with or enclosed in clinopyroxene and plagioclase is characterized by ti concentrations with an average value of 50 ppm these quartz grains have been equilibrated at high temperatures and pressures during the anatexis and were chemically isolated in ti poor phases during the low pressure cooling phase on the other hand the quartz enclosed in amphibole has much higher ti concentrations up to 140 ppm which is the result of further incorporation of ti released from the host mineral during the low pressure cooling diffusion modeling on one ti concentration profile in quartz enclosed in amphibole suggests fast cooling within 800 650 c with a rate of ca 0 2 c yr this study demonstrates that the application of the ti in quartz thermobarometer to lithologies with low fertility may be extremely helpful to constrain anatectic p t conditions and exhumation history of migmatized orogen basements

parallel trends in organic and inorganic carbon isotopes across the permian triassic boundary stable carbon isotope ratios in both inorganic and organic reservoirs have been widely applied to model environmental and sedimentological changes on a global scale most studies dealing with major extinction events have used the record of inorganic carbon in this paper the authors report the relation between shifts in carbon 13 content of organic matter and coexisting carbonate fractions at a major extinction event the permian triassic boundary they found that both delta sup 13 c sub carb and delta sup 13 c sub org of the surface ocean varied dramatically across the boundary but the fractionation delta sup 13 c between organic matter and carbonate remained constant this result appreciably restricts the interpretation of changes in the carbon cycle during this critical interval the new data are best explained by a combination of two mechanisms for variation in delta sup 13 c sub carb 1 burial and erosion of organic carbon with a long time constant and 2 sequestration of organic carbon into shallow and deep oceanic reservoirs with a shorter time constant for application to their case the first mechanism is limited by possible buildup of marine pco sub 2 which would increase the isotopic fractionation factor the second mechanism is limited in application to short term transient variations in delta sup 13 c modelingmore of the carbon cycle and its variations of delta sup 13 c must take both mechanisms into account less

extension of cathaysian flora during the permian climatic and paleogeographic constraints abstract recent paleobotanic investigations have been described during the late permian intermingled cathaysian south china block gondwanian and euramerian flora assemblage in oman arabian plate by analogy with present rainforest flora cathaysian floral elements in northeastern gondwana require permanent precipitation even if a short dry season may be endured on the contrary eurasian flora is most probably adapted to dryness we investigate the temporal and spatial extension of this surprising flora assemblage using numerical climatic simulations and paleomagnetic reconstructions we suggest that the settlement of cathaysian flora was possible as soon as this area reached about 20 s according to paleomagnetic data the southeastern arabian plate reached this latitude during late permian which exactly corresponds to the age of the oldest discovered cathaysian flora elements in oman moreover the paleomagnetic configuration of plates allows for easy chinese to gondwana connections using migrating blocks in the tethys or island arcs however the climatic simulations suggest the presence of a dry season lasting about 5 months in southeastern arabia such precipitation conditions would probably prevent the settlement of cathaysian plants we thus propose that the intermingled assemblage reflected the paleoenvironmental conditions cathaysian plants grew in a flood plain with perennial water supply whereas euramerian plants lived out of the flood plain over adjacent hills where water was only supplied by seasonal precipitation migration paths of these different floras are also discussed

vertebrate extinction across permian triassic boundary in karoo basin south africa distinct assemblages of paleosols above and below the permian triassic boundary in the karoo basin of south africa are evidence for reorganization of ecosystems following this greatest of all mass extinctions the permian triassic boundary is recognized from the last appearance of dicynodon and from a series of negative excursions in the isotopic composition of carbon within therapsid tusks pedogenic carbonate nodules and organic matter the boundary is also marked by laminated beds with very weakly developed paleosols a change from purple 10r to brownish red 2 5yr paleosols and a thin 10 cm claystone breccia of reworked soil clasts paleoclimatic changes include a shift from arid and highly seasonal paleoclimate inferred from diffuse and shallow calcareous nodules in permian paleosols to semiarid and less seasonal paleoclimate inferred from deep and well focused calcic horizons in triassic paleosols an earliest triassic shift to warmer and wetter paleoclimate is also indicated by increased chemical weathering abundance of lycopsids and diversity of labyrinthodonts permian paleosols have root traces comparable to those of open shrubland and riparian woodland whereas triassic paleosols have root traces and profile forms like soils of open woodland this is a significant paleoenvironmental change but not as dramatic a change as would be expected from the devastating extinctions of 88 of fossil vertebrate genera latest permian therapsid reptiles were diverse and ecologically specialized in contrast the principal earliest triassic therapsid lystrosaurus was a burrower with no specific habitat preference its short internal nares barrel chest and high neural spines would have given it greater aerobic scope than preexisting therapsids and may have been an advantage under conditions of hypercapnia and hypoxia these adaptations and associated ecosystem changes are compatible with widespread vertebrate mortality by acidosis and pulmonary edema in a post apocalyptic greenhouse created by the voluminous release of methane from shallow marine and permafrost clathrates

fungal event and palynological record of ecological crisis and recovery across the permian triassic boundary the end of the permian period was marked by the most severe mass extinction in the geologic record detailed quantitative study of pollen and spores from shallow marine deposits spanning the permian triassic p tr boundary in israel reveals a sequence of palynological ecological stages reflecting a major crisis among land plants the disappearance of the gymnosperm dominated palynoflora of the late permian lueckisporites virkkiae zone is recorded at a claystone horizon containing almost exclusively abundant fungal remains and carbonized terrestrial plant debris this fungal spike is followed by a zone dominated by marine acritarchs and a succession showing ecological recovery with abundantlycopodsporesandeventualreappearanceofbisaccategymnospermpolleninthe earlytriassic thelatestpermianproliferationoffungiisrecognizableworldwideandcan be correlated with other paleontological and geochemical markers of a global ecological disaster

palaeoenvironments of the permian triassic transition sections in kashmir india abstract detailed measurements of two permian triassic boundary sections at guryul ravine and pahlgam in kashmir indicate continuous sedimentation across the boundary though with a marked change from shallow storm influenced shelf to deeper shelf below wave base successive shell beds through the 2 5 m thick transitional latest permian section at guryul formed as in situ accumulations with little sign of either erosional breaks or condensation faunal change takes place gradually in the late permian transition beds as elsewhere in the tethyan sections there is no major event layer at the permian triassic boundary and little evidence for dysaerobic conditions both the kashmir and east greenland permian triassic sections have sedimentation rates that are orders of magnitude greater than at the condensed meishan reference section they show that the end permian extinction was associated with transgression but not with immediate onset of anoxic conditions macrofaunal extinction seems associated with reduction in primary production which would also explain the dwarfism of fossils found in all permian triassic sections studied so far