reply to discussion of the paper high to ultrahigh pressure uhp ductile shear zones in the sulu uhp metamorphic belt china implications for continental subduction and exhumation by zhao et al

alkyldibenzofurans in terrestrial rocks influence of organic facies and maturation abstract dibenzofuran dbf dibenzothiophene dbt and phenanthrene phe have been determined along with their methyl derivatives mdbfs mdbts mps in coals carbonaceous shales and mudstones of lower cretaceous to upper carboniferous ages from the elmworth gas field canada and from the sakoa madagascar and ruhr coal germany basins the samples contained mainly terrestrial organic matter with thermal maturities in the 0 7 1 9 mean vitrinite reflectance rr range the pronounced predominance of mdbfs over mdbts in the sakoa samples is typical of plant debris deposited in lacustrine swamp environments onset of intense mdbf generation occurs at fairly low rank 0 77 rr as indicated by elevated concentrations of 50 120 g mdbfs g total organic carbon toc influences of lithology organic matter type and maturity on distributions of the target compounds were extracted from the molecular concentration data by multivariate statistical methods such as principal components analysis pca and fuzzy c means cluster analysis with nonlinear mapping nlm a specific source effect on 1 mdbt concentrations suggests that lichens contributed to the senescent coal forming forest in the sakoa coal basin alkyldibenzofurans hence are potential lichen biomarkers mdbfs can be used as maturity indicators only beyond 1 0 rr where ruhr coals displayed a distinct increase in the 1 4 mdbf ratio

partial transformation of gabbro to coesite bearing eclogite from yangkou the sulu terrane eastern china an ultra high pressure uhp metamorphic slab at yangkou beach near qingdao in the sulu region of china consists of blocks of eclogite facies metagabbro metagranitoid ultramafic rock and mylonitic orthogneisses enclosed in granitic gneiss a gradational sequence from incipiently metamorphosed gabbro to completely recrystallized coesite eclogite formed at ultra high pressures was identified in a single 30 m block metagabbro is preserved in the core whereas coesite eclogite occurs along the block margins the metagabbro contains an igneous assemblage of pl aug opx qtz bt ilm ti mag it shows relict magmatic textures and reaction coronas fine grained garnet developed along boundaries between plagioclase and other phases primary plagioclase broke down to ab ky ms zo grt amp augite is rimmed by sodic augite or omphacite whereas orthopyroxene is rimmed by a corona of cum act and omp qtz layers or only omp qtz in transitional rocks augite and orthopyroxene are totally replaced by omphacite and the lower pressure assemblage ab ky phn zo grt coexists with domains of omp jd70 73 ky phn in pseudomorphs after plagioclase both massive and weakly deformed coesite bearing eclogites contain omp ky grt phn coe qtz rt and preserve a faint gabbroic texture coesite inclusions in garnet and omphacite exhibit limited conversion to palisade quartz some intergranular coesite and quartz pseudomorphs after coesite also occur assemblages of the coronal stage transitional and uhp peak occurred at about 540 50 c at c 13 kbar 600 800 c at 15 25 kbar and 800 850 c at 30 kbar respectively garnet from the coronal through the transitional to the eclogite stage rocks show a decrease in almandine and an increase in grossular pyrope components garnet in low grade rocks contains higher mno and lower pyrope components the growth textures of garnet within pseudomorphs after plagioclase or along grain boundaries between plagioclase and other phases are complex the application of garnet zoning to estimate p t should be carried out with caution some garnet enclosing quartz aggregates as inclusions shows radial growth boundaries these quartz aggregates as well as other primary and low p phases persisted metastably at uhp conditions due to sluggish reactions resulting from the lack of fluid during prograde and retrograde p t evolution

seasonal climatic forcing of alpine glaciers revealed with orbital synthetic aperture radar the evolution of four dynamic radar glacier zones at the surface of an alpine icefield in british columbia is monitored using a time series of 35 first european remote sensing satellite ers 1 synthetic aperture radar sar images acquired from 1992 to 1994 these zones result from changing wetness and textural properties and appear to represent 1 cold snow with no liquid water present 2 an initial melt front with an upper boundary near the elevation of the 0 isotherm 3 metamorphosed rapidly melting first year snow with a rough or pitted surface and 4 bare ice this interpretation is aided by temperature and runoff data air photographs and field measurements of snowpack properties acquired simultaneously with two ers i sar scenes ice surface elevations derived from 1 50 000 topographic maps and simulations of radar backscatter from a geometric optics model of surface scattering meltwater production is affected by the development of zones 2 3 and 4 which form migrate up elevation and disappear each year between april and september

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

earliest triassic claystone breccias and soil erosion crisis abstract chemostratigraphic methods 13corg for pinpointing the permian triassic boundary in nonmarine rocks of antarctica australia and south africa have drawn attention to unusual claystone breccias at this horizon of the greatest extinction in the history of life on earth these rocks differ from other breccias in having a high proportion of clasts with birefringence microfabrics sepic plasmic fabrics characteristic of soils and can be called sepic pedoliths in the terminology of soil science at many localities earliest triassic sepic pedoliths are thin 5 15 cm beds but some fill shallow paleochannels and pinch out laterally other non marine breccias at the permian triassic boundary are dominated by fragments of coal pedogenic carbonate nodules and deeply weathered volcanic rock fragments earliest triassic sepic pedoliths record an unusually severe and widespread episode of soil erosion associated with forest dieback at the permian triassic boundary comparable sepic pedoliths are found in debris flows after clear cutting of forests in western oregon today studies of these modern deposits show that sepic soil peds do not withstand weathering for more than a few months such clayey clasts are held together mainly by roots and fungi which decay rapidly in soils and streams these modern analogs demonstrate that terminal permian soil erosion was rapid and profound sepic pedoliths are also known at other times of mass extinction such as the triassic jurassic boundary but are not yet known before the devonian advent of trees and forested clayey soils

griesbachian earliest triassic palaeoenvironmental changes in the salt range pakistan and southeast china and their bearing on the permo triassic mass extinction abstract facies and faunal analysis from pakistan and china show that the permo triassic mass extinction of marine invertebrate faunas was associated with a spectacularly rapid griesbachian transgression which lead to the widespread establishment of deep water anoxic and dysoxic conditions the extinction event was thus caused by habitat loss due to the extensive development of inhospitable conditions the initial griesbachian transgression in pakistan produced extensive shallow normal marine conditions in which permian holdover taxa were able to survive until the development of dysaerobic facies in the late griesbachian the exceptionally complete sections of china show a three phased deepening and extinction event beginning in the latest permia by the late griesbachian a variety of dysaerobic and anaerobic facies were developed in all the regions studied several of these contain evidence for minimal sulphate reducing activity suggesting that marine productivity and thus organic matter flux to the sediments was very low in early triassic seas

global coal gap between permian triassic extinction and middle triassic recovery of peat forming plants early triassic coals are unknown and middle triassic coals are rare and thin the early triassic coal gap began with extinction of peat forming plants at the end of the permian ca 250 ma with no coal known anywhere until middle triassic 243 ma permian levels of plant diversity and peat thickness were not recovered until late triassic 230 ma tectonic and climatic explanations for the coal gap fail because deposits of fluctuating sea levels and sedimentary facies and paleosols commonly found in coal bearing sequences are present also in early triassic rocks nor do we favor explanations involving evolutionary advances in the effectiveness of fungal decomposers insects or tetrapod herbivores which became cosmopolitan and much reduced in diversity across the permian triassic boundary instead we favor explanations involving extinction of peat forming plants at the permian triassic boundary followed by a hiatus of some 10 m y until newly evolved peat forming plants developed tolerance to the acidic dysaerobic conditions of wetlands this view is compatible not only with the paleobotanical record of extinction of swamp plants but also with indications of a terminal permian productivity crash from delta sup 13 c sub org and total organic carbon of both nonmarine and shallow marine shales 205 refs 3 figs more 3 tabs less

u pb zircon geochronology and tempo of the end permian mass extinction the mass extinction at the end of the permian was the most profound in the history of life fundamental to understanding its cause is determining the tempo and duration of the extinction uranium lead zircon data from late permian and early triassic rocks from south china place the permian triassic boundary at 251 4 0 3 million years ago biostratigraphic controls from strata intercalated with ash beds below the boundary indicate that the changhsingian pulse of the end permian extinction corresponding to the disappearance of about 85 percent of marine species lasted less than 1 million years at meishan a negative excursion in 13 c at the boundary had a duration of 165 000 years or less suggesting a catastrophic addition of light carbon

geophysical profiling across the sulu ultra high pressure metamorphic belt eastern china abstract the largest ultra high pressure metamorphic uhpm belt in the world is located along the dabie sulu region which tectonically belongs to the east part of the central orogenic belt of china integrated geophysical investigations of using deep seismic reflection mt and geothermal observations have been carried out in the sulu area since 1997 the results of integrated interpretation suggest the existence of three features 1 a rift beneath the lianshui basin by the jiashan xionshui fault 2 a special crustal pattern called the magmatic multi arch structure occurs beneath the northern sulu uhpm zone and 3 a northwest dipping regional thrust crosses the sulu crust representing the intracontinental subduction of the yangtze craton beneath the sulu metamorphic belts after collision between the yangtze and sino korean cratons a magmatic multi arch structure consists of some arched reflectors that occur in both the lower and the upper crust where arched reflectors coincide with granitoid plutons the multi arch structures are common in eastern china where many mesozoic granitoid plutons of different scales occur the crustal structures in the sulu metamorphic belts resulted from intensive dynamic processes following the triassic collision between the yangtze and sino korean cratons the formation and exhumation of uhpm rocks followed the collision and then intracontinental subduction of the yangtze craton beneath the dabie sulu terranes took place in the early and middle jurassic in the late jurassic the sulu lithosphere turned to an extensional regime large scale granitic intrusions occurred in eastern china these likely resulted from lithospheric thinning and asthenospheric uplifting the granitic intrusions came to a climax during the cretaceous and were followed by rifting along existing faults in the early eogene resulting in many petroleum basins the granitoid emplacement that generated the magmatic multi arch structure and the rift were consequences of the lithospheric thinning process and deep intracontinental subduction of the yangtze craton beneath the sulu metamorphic belt might partially contribute to the lithospheric thinning

permian triassic boundary ptb in the lower yangtze region southeastern china a new discovery of deep water archive based on organic carbon isotopic and u pb geochronological studies abstract the lower yangtze region of southeastern china is an important area for the study of permian triassic boundary ptb in this region many well known ptb sections e g meishan have been investigated widely and extensively however these sections are dominantly in shallow water settings and data from deep water areas are lacking to fill the gap we conducted a field survey recently and found a deep water ptb section with relatively continuous deposition using integrated organic carbon isotopic and u pb geochronological studies this well exposed and fresh section is located at niushan xuancheng city anhui province 90 km west of the well known meishan section which is the ptb global boundary stratotype section and point the organic carbon isotope curve of the section contains three positive excursions pcies and two negative excursions ncies which can be well correlated with other ptb sections as well as with wuchiapingian changhsingian boundary wcb sections worldwide they archive the original ptb and wcb signatures further u pb dating of magmatic zircons in volcanic ashes validates this new finding i e the ptb interval between 252 49 0 76 ma and 251 74 0 77 ma carbon isotopes of ptb sections in south china reflect the regional paleogeography the two ncies ncie 2 and ncie 3 across the ptb transition are most likely caused by widespread large scale volcanic activity in contrast the ncie 1 near the wcb is possibly related to an increase in the productivity of organic matter as a result of transgression and a change in the organic matter type from terrigenous to marine

abundance anomalies of aromatic biomarkers in the permian triassic boundary section at meishan china evidence of end permian terrestrial ecosystem collapse several aromatic biomarkers detected in solvent extracts and kerogen pyrolysates from samples of the global stratotype section and point gssp for the permian triassic boundary at meishan china show distinctive relative abundance anomalies that may be related to the end permian biotic crisis on land enrichment of dibenzofuran homologues across the permian triassic boundary may corroborate the concept of excessive soil erosion following loss of rooted vegetation enrichment of alkylphenol entities occurs just below the main marine mass extinction horizon and prior to the characteristic end permian 13c decline the alkylphenols were probably derived from lignin and may provide a molecular record of dieback of woody vegetation highly decreased relative abundances of dibenzothiophenes could be indicative of excessive supply of fe2 it is suggested that fe2 was land derived and may have originated from soils in addition to the permian triassic boundary interval biomarker abundance anomalies also occur around the wuchiapingian changhsingian boundary in the basal part of the meishan section

end permian mass extinction in the oceans an ancient analog for the twenty first century the greatest loss of biodiversity in the history of animal life occurred at the end of the permian period 252 million years ago this biotic catastrophe coincided with an interval of widespread ocean anoxia and the eruption of one of earth s largest continental flood basalt provinces the siberian traps volatile release from basaltic magma and sedimentary strata during emplacement of the siberian traps can account for most end permian paleontological and geochemical observations climate change and perhaps destruction of the ozone layer can explain extinctions on land whereas changes in ocean oxygen levels co2 ph and temperature can account for extinction selectivity across marine animals these emerging insights from geology geochemistry and paleobiology suggest that the end permian extinction may serve as an important ancient analog for twenty first century oceans

high to ultrahigh pressure uhp ductile shear zones in the sulu uhp metamorphic belt china implications for continental subduction and exhumation high to ultrahigh pressure hp uhp metamorphic rocks that resulted from deep continental subduction and subsequent exhumation in the sulu orogenic belt china have experienced multiphase deformation and metamorphic overprint during its long journey to the mantle and return to the surface hp uhp shear zones are strain localized weak zones on which the uhp slab is transported over long distances hp uhp shear zones are well exposed along a 200 km belt in the sulu uhp metamorphic belt the shear zones lie structurally below the uhp rocks and above the non uhp rocks suggesting the early exhumation of the uhp rocks by thrusting the large area distribution hp uhp nature high strain and structural association of the shear zones with the uhp rocks suggest that the shear zones are probably a regional detachment developed during the early stage of exhumation of the uhp rocks kinematic indicators suggest top to the n nw motion of the uhp slab during the exhumation which combined with isotope signature in mesozoic igneous rocks leads us to the interpretation that the subduction polarity is the north china plate down to the south rather than the yangtze plate down to the north in the sulu region

global warming and the end permian extinction event proxy and modeling perspectives abstract the mass extinction event that occurred at the close of the permian period 252 million years ago represents the most severe biodiversity loss in the ocean of the phanerozoic the links between the global carbon cycle climate change and mass extinction are complex and involve a whole range of often inter related geochemical biological ecologic and climatic factors it has become widely accepted that the end permian mass extinction was associated with a global warming event because the age of the siberian trap eruption a potentially massive source of carbon dioxide coincides within error with the extinction event however geologic data that are in support of this global warming event are relatively sparse the chain of events and the causal relationship between the eruption of siberian traps and mass extinction is not well established global warming in particular has only been reported from limited proxy data and climate models for which the pco2 in the atmosphere just before and during the end permian extinction event is poorly known this study critically assesses both the proxy climate data and the existing paleoclimate simulations with the goals of assessing our current understanding of the link between mass extinction and climate change and providing some guidance for future studies proxies indicate that prior to the end permian extinction event tropical sea surface temperatures ranged from 22 to 25 c and possible pco2 values ranged from 500 to 4000 ppm before the extinction event during the peak extinction tropical temperatures rose up to 30 c while pco2 perhaps increased up to 8000 ppm climate models that use different pre event pco2 values show similar amount of co2 doubling to replicate the observed carbon isotope excursions we find that the temperature anomaly during the end permian extinction is consistent with 1 5 doublings of atmospheric pco2 and that the implied climate sensitivity is 5 6 c within the upper range of values produced by climate models

greenland ice sheet surface properties and ice dynamics from ers 1 sar imagery c band synthetic aperture radar sar imagery from the european space agency s ers 1 satellite reveals the basic zonation of the surface of the greenland ice sheet the zones have backscatter signatures related to the structure of the snowpack which varies with the balance of accumulation and melt at various elevations the boundaries of zones can be accurately located with the use of this high resolution imagery the images also reveal a large flow feature in northeast greenland that is similar to ice streams in antarctica and may play a major role in the discharge of ice from the ice sheet

impacts of global warming on permo triassic terrestrial ecosystems geologists and palaeontologists have expressed mixed views about the effects of the end permian mass extinction on continental habitats and on terrestrial life current work suggests that the effects on land were substantial with massive erosion following the stripping of vegetation associated with long term aridification and short term bursts of warming and acid rain wildfires at the permo triassic boundary contributed to the removal of forests and the prolonged absence of forests from the earth s surface for up to 10 myr these physical crises on land impinged on the oceans suggesting tight interlocking of terrestrial and marine crises levels of extinction on land may well have been as high as in the sea and this is certainly the case for tetrapods the mass extinction seems to have been less profound for plants and insects but it is hard at present to disentangle issues of data quality from reductions in abundance and diversity several killing agents have been proposed and of these tetrapods may have succumbed primarily to acid rain mass wasting and aridification plants may have been more affected by the sudden effects of heating and wildfires and the crisis for insects has yet to be explored

abnormal pollen grains an outcome of deteriorating atmospheric conditions around the permian triassic boundary records of abnormal gymnosperm pollen morphotypes from coeval localities in russia and nw china provide independent and unique evidence of deteriorating atmospheric conditions at the close of the permian although at similar palaeolatitude the vologda region of european russia and the junggar basin of xinjiang province china were thousands of kilometres apart and on different tectonic plates the co occurrence of the megaspore otynisporites eotriassicus fuglewicz 1977 and its restricted distribution elsewhere in marine sections with either late permian ammonoids or the basal triassic conodont marker hindeodus parvus confirms the age range and correlation of the russian and nw chinese sections in three chinese sections rapid changes in carbon isotopic 13 c org composition of between 4 and 10 occur over the intervals showing abnormal pollen these patterns reflect bioclastic facies contributions responding to local environmental changes they are nevertheless coincident with global perturbations in the atmosphere caused by extensive volcanic activity around the permian triassic boundary

mass extinction of peat forming plants and the effect on fluvial styles across the permian triassic boundary northern bowen basin australia abstract the most spectacular extinction event in earth s history occurred across the permian triassic boundary in the northern bowen basin a major coal bearing sedimentary basin in eastern australia a long lived c 9 myr cold climate peat mire ecosystem collapsed at the permian triassic boundary when the vast majority c 95 of peat producing plants became extinct the environmental change marked by the permian triassic boundary is expressed as an abrupt and sharp change in sedimentary regime at the contact between the rangal coal measures and the sagittarius sandstone the stratigraphic record shows no diminution in the thickness lateral extent or spatial distribution of coal seams prior to the boundary event the abrupt ecological shift at the permian triassic boundary was coincident with and interrelated to a change in landscape attributes and fluvial style the boundary shift is considered to reflect a short period radical atmospheric change accompanied by an abrupt change in plant ecosystems however palynological data indicate that it was preceded by a more gradual gross taxonomic progression in the floral succession the boundary shift is unlikely to reflect change in the tectonic setting of the northern bowen basin because the detrital character of clastic sediment supply shows no provenance change within the boundary sequence the late permian fluvial style is characterised by large scale up to 1 km wide sandstone dominated low sinuosity trunk river channel deposits the trunk river channels were flanked by extensive levee composite crevasse splay systems channel tracts were relatively stationary in position over enduring periods and developed stacked sediment accumulations up to 30 m thick the constrained character of the late permian trunk river systems was most likely due to progressive compaction of thick tracts of peat substrate and the stabilising effect of vegetation adjacent to the channel complex the well developed crevasse splays coupled with the low sinuosity style of the fluvial channels might suggest a perennial fluvial system characterised by short discharge periods as common in high latitude settings the fluvial architecture of the sagittarius sandstone the basal formation of the lower triassic rewan group is characterised by sheet like elements suggestive of broad shallow channels in a deforested braid plain setting the channel deposits are considered to represent highly mobile sandy systems dominated by a flashy runoff regime the mass extinction of plants in the northern bowen basin at the permian triassic boundary thus had a significant impact on the early triassic landscape and fluvial architecture

where is the north china south china block boundary in eastern china the qinling dabieshan belt results from the collision of the north china and south china blocks the eastern extension of the belt the sulu area consists of several stacked units from top to bottom these are 1 a weakly metamorphosed slate sandstone unit of neoproterozoic paleozoic age 2 a gneiss quartzite unit metamorphosed under high pressure p conditions 3 a marble amphibolite unit 4 an ultrahigh p unit that was very deeply subducted and then exhumed and 5 a migmatitic dome resulting from the melting of ultrahigh p rocks all these units underwent the same deformation which was characterized by a top to the northwest extensional ductile shearing during their exhumation granulite facies restites in the migmatite are not significantly different from granulitized eclogites derived from the ultrahigh p rocks the migmatite exhibits the same structural and petrologic evolution as that determined for the other units the resemblance of petrologic and structural features and the lack of ocean basin rock shows that the boundary between the north china block and south china block must be placed north of the sulu area

palaeotethys seawater temperature rise and an intensified hydrological cycle following the end permian mass extinction abstract the end permian mass extinction has been associated with severe global warming main stage volcanism of the siberian traps occurred at or near the extinction interval and has been proposed as a likely greenhouse catalyst in this study a high resolution 18o record is established using diagenetically resistant apatite of conodonts and low mg calcite of brachiopods from stratigraphically well constrained permian triassic p tr boundary successions in northwestern iran a new evaluation is made for previously published conodont 18o values from south china and revised palaeotemperatures are presented together with new data from wuchiapingian to griesbachian sections in iran 18o data from p tr sections in iran document tropical sea surface temperatures sst of 27 33 c during the changhsingian with a negative shift in 18o starting at the extinction horizon translating into a warming of ssts to over 35 c the results are consistent with re calculated ssts of the south chinese sections warming was associated with an enhanced hydrological cycle involving increased tropical precipitation and monsoonal activity in the tethys sea global warming intensification of the hydrological cycle and associated processes vertical water column stratification eutrophication and subsequent local anoxia may all have facilitated an extinction event

controls on regional marine redox evolution during permian triassic transition in south china abstract although oceanic anoxia is regarded as a leading cause of the permian triassic boundary ptb mass extinction its timing extent and underlying causes remain unclear here we conducted a high resolution fe s c mo geochemical study of the entire changhsingian and lowermost induan succession in a carbonate ramp setting at ganxi western hubei province south china six stratigraphic units representing discrete redox intervals were identified based on integrated fe s c mo data units i iii are of latest wuchiapingian to early changhsingian age with units i and iii characterized by euxinia and unit ii by uncertain redox conditions unit iv of mid changhsingian age records a gradual transition from euxinic to ferruginous conditions units v and vi spanning the latest permian mass extinction lpme to earliest triassic interval were deposited under dominantly ferruginous conditions punctuated by both euxinic and oxic episodes redox variations at ganxi were controlled by contemporaneous oceanographic changes in the upper oceanic thermocline region i euxinia in units i and iii may record elevated marine productivity as suggested by mean organic carbon accumulation rates or ocar of 6 5 and 5 1 mg cm2 kyr respectively that was possibly related to upwelling ii the euxinic to ferruginous transition from unit iv to units v vi can be attributed to a combination of reduced sulfate availability and rising terrigenous iron inputs mean fe of 1 7 and 3 9 respectively for units v iv and vi compared to 1 0 for units i iii and iii transient intervals of euxinia in units v and vi were facilitated by enhanced sulfate fluxes related to episodic volcanism during this interval an integration of the redox data from ganxi with previously published data from the shangsi and xiakou sections suggests that enhanced weathering fluxes were most likely the key factor controlling the marine redox transition from euxinic to ferruginous conditions during the latest permian across the south china region

large areal extent of ultrahigh pressure metamorphism in the sulu ultrahigh pressure terrane of east china new implications from coesite and omphacite inclusions in zircon of granitic gneiss abstract coesite and omphacite inclusions have been identified for the first time as minute inclusions in zircon from amphibolite facies granitic orthogneiss in the sulu ultrahigh pressure uhp metamorphic terrane of eastern china by raman spectroscopy and microprobe analyses the occurrences of these minerals in the voluminous granitic gneiss of sulu support a regional and pervasive uhp metamorphic event that predated regional amphibolitic retrogression taking into account the widespread discoveries of coesite in other lithologies we thus conclude that a substantial crustal component in the sulu uhp metamorphic terrane appears to have shared a common history of triassic subduction to mantle depths and later exhumation

where is the north china south china block boundary in eastern china comment and reply where is the boundary between the north china block and the south china block in the sulu area the answer to this question is important for understanding the ultrahigh pressure p collisional process and tectonic framework of northeast asia the wulian yantai fault or tan lu fault has been

an integrated biomarker isotopic and palaeoenvironmental study through the late permian event at lusitaniadalen spitsbergen abstract the largest extinction of the phanerozoic occurred near the permian triassic p tr boundary some 252 ma ago several scenarios and drivers have been proposed for this event here we report for the first time an integrated study comprising sedimentological data biomarker distributions abundances and selected stable carbon and hydrogen isotopes along with bulk isotopes 34spyrite 13ccarb 13corg for a late permian section from lusitaniadalen spitsbergen norway sedimentological and geochemical data support a marine transgression and collapse of the marine ecosystem in the late permian strong evidence for waxing and waning of photic zone euxinia throughout the late permian is provided by chlorobiaceae derived biomarkers including 13c data and 34spyrite implying multiple phases of h2s outgassing and potentially several pulses of extinction a rapid decrease in abundance of various land plant biomarkers prior to the marine collapse event indicates a dramatic decline of land plants during the late permian and or increasing distance from palaeoshoreline as a consequence of sea level rise changes in d of selected biomarkers also suggest a change in source of organic matter om or sea level rise we also found biomarker and isotopic evidence for a phytoplanktonic bloom triggered by eutrophication as a consequence of the marine collapse compound specific isotope analyses csia of algal and land plant derived biomarkers as well as 13c of carbonate and bulk om provide strong evidence for synchronous changes in 13c of marine and atmospheric co2 attributed to a 13c depleted source the source could be associated with isotopically depleted methane released from the melting of gas clathrates and or from respired om due to collapse of the marine ecosystem

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

the organic geochemistry of coal from plant materials to coal coalification is a process that transforms plant remains under the influence of time temperature and possibly pressure to a black generally lustrous solid organic fossil fuel having a very complex chemistry although much has been learned in the past two centuries on coal chemistry we still have little knowledge of the way plant materials undergo these transformations the problem has been the existence of adequate characterization tools the advent of some new tools for structural elucidation of macromolecules has led to some revised thinking on coalification originally thought to be a process involving the full degradation of plant remains and subsequent reconstitution of these remains the general consensus today is that the process involves a selective preservation of certain resistant plant components followed by some minor reorganization of the biopolymers that survive the major components of plants do degrade and the resistant ones often constitute only a small fraction of the original mass of the plant materials this paper examines the most recent literature concerning coalification and focuses on the chemistry associated with coalification of certain recognizable plant remains that have been at the center of research activity for the past two decades thus we examine the recent knowledge of the chemistry of resistant biopolymers in extant and fossil wood cuticles resins spores and algae knowledge that has been assembled to establish the reaction pathways towards coal macromolecules

laboratory measurements of sea ice connections to microwave remote sensing the connections between laboratory measurements and remote sensing observations of sea ice are explored the focus of this paper is on thin ice which is more easily simulated in a laboratory environment the authors summarize results of c band scatterometer measurements and discuss how they may help in the interpretation of remote sensing data they compare the measurements with observations of thin ice from ers and airborne radar data sets they suggest that laboratory backscatter signatures should serve as bounds on the interpretation of remote sensing data they examine these bounds from the perspective of thin ice signatures the effect of temperature and surface processes such as frost flowers and slush on these signatures controlled experiments also suggest new directions in remote sensing measurements the potential of polarimetric radar measurements in the retrieval of thickness of thin ice is discussed in addition to the radar results the authors discuss the importance of low frequency passive measurements with respect to the thickness of thin ice

analysis of synthetic aperture radar data collected over the southwestern greenland ice sheet analyses of the first aircraft multi frequency polarimetric synthetic aperture radar sar data acquired over the southwestern greenland ice sheet are presented data were collected on 31 august 1989 by the jet propulsion laboratory sar using the nasa dc 8 aircraft along with curvilinear patterns associated with large scale morphologic features such as crevasses lakes and streams frequency and polarization dependencies are observed in the p l and c band image products

altered river morphology in south africa related to the permian triassic extinction the permian triassic transition in the karoo basin of south africa was characterized by a rapid and apparently basin wide change from meandering to braided river systems as evidenced by preserved sedimentary facies this radical changeover in river morphology is consistent with geomorphic consequences stemming from a rapid and major die off of rooted plant life in the basin evidence from correlative nonmarine strata elsewhere in the world containing fluvial permian triassic boundary sections suggests that a catastrophic terrestrial die off of vegetation was a global event producing a marked increase in sediment yield as well as contributing to the global 13 c excursion across the permian triassic boundary

snow and ice facies variability and ice layer formation on canadian arctic ice caps 1999 2005 1 time series of enhanced resolution data from the seawinds scatterometer aboard quikscat were used to map the distribution of snow and ice surface facies and ice layer formation in the percolation zone on ice caps in the queen elizabeth islands during the period 1999 2005 iterative self organizing data analysis classification of the mean postfreeze up biweekly average 0 signal for the 7 year period resulted in the delineation of four snow and ice surface facies interpreted as the percolation saturation superimposed ice and glacier ice zones analysis with national centers for environmental prediction national center for atmospheric research reanalysis reveals that changes in geopotential height in the troposphere 700 500 and 300 hpa and air temperature 700 hpa level are positively negatively correlated with area changes in the glacier ice percolation and saturation zones and changes in facies boundary elevation the change in biweekly averaged backscatter following the freeze up periods between successive autumns was used to map changes in the distribution of ice layers formed by meltwater percolation and refreezing in the snowpack within the percolation zone strongly positive air temperature anomalies at the 700 hpa level in 2001 and 2005 are consistent with extensive ice layer formation in the percolation zones of all ice caps such large interannual changes in ice layer formation are likely associated with large changes to the density profile of the snowpack and may be associated with surface elevation changes that are unrelated to changes in surface mass balance

diagenetic and detrital origin of moretane anomalies through the permian triassic boundary abstract many biogeochemical anomalies coincide with the late permian extinction lpe 252 28 ma several mechanisms have been proposed to explain the moretane hopane anomaly that has been identified in samples from meishan gssp section in southeastern china here we report homohopane 2 and 3 methylhomohopane and lithological data for a drill core from the meishan section in southeastern china three intervals of elevated c 30 moretane hopane ratios are recorded in the lungtan yinkeng and helongshan formations moretane hopane ratios of c 31 34 homohopanes and the 2 and 3 methylhomohopanes display the same stratigraphic patterns as the c 30 moretane hopane record in light of the multiple and parallel moretane anomalies for the homohopane and 2 and 3 methylhomohopane series enhanced input from higher plant organic matter such as coal and peat does not adequately explain the observed isomer patterns correlation of high moretane hopane ratios with low c 35 homohopane index hhi and high hopane sterane values suggest increased input of hopanoids from oxic soils additionally moretane hopane ratios show excellent correlations with total clay percentages and specific clay types particularly chlorite illite and mixed layer illite smectite we conclude that a combination of episodic hopanoid input from soil bacteria and diagenetic effects related to redox and detrital clays generated the unique moretane hopane patterns at meishan similar relationships of ts ts tm with redox source indicators and lithology indicate that ts ts tm is affected by the same factors controlling the moretane hopane ratios berthierine a clay that requires reducing conditions for formation was detected in samples from the lungtan formation we are unable to determine from our results whether the berthierine is authigenic or detrital but future determination of the origin of berthierine at meishan may offer additional environmental insight no link between diasteranes and lithology was observed in this study suggesting that diasteranes are relatively unaffected by the detrital clay component of the meishan sediments in total the results point toward the complex role of source input lithology and depositional redox conditions in the transformation of organic matter during maturation future work is required to elucidate the lithological effects on diagenetic processes including biomarker genesis isomerization and thermal degradation

occurrence and field relationships of ultrahigh pressure metagranitoid and coesite eclogite in the su lu terrane eastern china coesite eclogite is associated with metagranitoid in a 50 100 m 2 outcrop within the regionally developed amphibolite facies su lu orthogneiss primary intrusive relationships between the metagranitoid and basic rocks and bulk chemistry analyses show that together they represent a composite igneous body that has subsequently been strongly deformed and metamorphosed the presence of rutile sodie pyroxene corona garnet and possible pseudomorphs after coesite all suggest very high pressures of metamorphism in the metagranitoid this is the first documented occurrence of ultrahigh pressure uhp metagranitoid outside of the european alps the existence of uhp metagranitoid shows that low density of rocks does not necessarily prevent subduction to mantle depths even at peak metamorphic conditions the uhp composite igneous body reported here would have a bulk density less than the mantle buoyancy forces may therefore have been important in the early exhumation of this unit other outcrops of coesite eclogite in the su lu region may also have been originally metamorphosed along with low density granitoid rocks

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

organic geochemistry across the permian triassic transition at the idrijca valley western slovenia abstract bulk and molecular stable c isotopic compositions and biomarker distributions provide evidence for a diverse community of algal and bacterial organisms in the sedimentary organic matter of a carbonate section throughout the permian triassic p tr transition at the idrijca valley western slovenia the input of algae and bacteria in all the upper permian and lower scythian samples is represented by the predominance of c15 c22 n alkanes odd c number alkylcyclohexanes c27 steranes and substantial contents of c21 c30 acyclic isoprenoids the occurrence of odd long chain n alkanes c22 c30 and c29 steranes in all the samples indicate a contribution of continental material the decrease of corg and ccarb contents increase of rock eval oxygen indices and 13c enrichment of the kerogen suggest a decrease in anoxia of the uppermost permian bottom water the predominance of odd c number alkylcycloalkanes c27 steranes and c17 n alkanes with 13c values 30 and 13c enrichment of the kerogens in the lowermost scythian samples are evidence of greater algal productivity this increased productivity was probably sustained by a high nutrient availability and changes of dissolved co2 speciation associated to the earliest triassic transgression a decrease of corg content in the uppermost scythian samples associated to a 13c depletetion in the carbonates up to 4 and individual n alkanes up to 3 4 compared to the upper permian samples indicate lowering of the primary productivity algae cyanobacteria and or higher degradation of the organic matter

petrologic and geochemical evidence for the formation of organic rich siliceous rocks of the late permian dalong formation lower yangtze region southern china abstract black shales are economically and scientifically important because they are commonly associated with high quality hydrocarbon source rocks and metal accumulations formed during periods of abrupt environmental change organic rich siliceous rocks of the late permian dalong formation developed extensively within middle upper yangtze region western yangtze platform however the formation mechanism of its formation in the lower yangtze region eastern yangtze platform remains a subject of debate due to a lack of outcrop exposure petrologic mineralogic and geochemical data are presented for three sections of the dalong formation within the lower yangtze region geochemical ratios including v v ni v cr ni co u th and v sc suggest that the dalong formation was deposited in an oxygen poor environment the elevated concentration of mo 100 ppm further suggests that free h2s existed in the bottom water which was favorable for the accumulation of large amounts of organic matter mo toc ratios reveal that water flow in the lower yangtze basin was moderately to strongly restricted during deposition of the dalong formation flow within the upper middle parts of the yangtze basin was also restricted suggesting that northern marginal basins on the yangtze platform formed part of a single ocean during the late permian i e changhsingian cherts of the dalong formation reflect high primary productivity similar to that of modern day upwelling zones which increased the amount of organic matter these results combined with previous work suggest that the long term oxygen poor conditions during deposition of the dalong formation were caused by restricted water circulation in a unique paleogeographic environment characterized by low latitude and submarine paleo highlands such settings of low latitude characterized by tropical climate favored the growth of siliceous zooplankton in the zones with submarine paleo highlands having created topographic barriers to water circulation restricted bottom water flow and oceanic anoxia during the late permian were likely the main controls on the accumulation of organic rich rocks elevated nutrient levels caused by frequent oceanic upwelling along the western margin of the south china craton and global volcanism at this time facilitated siliceous organism productivity

a potential biomarker for the permian triassic ecological crisis abstract a unique biomarker a c33 n alkylcyclohexane n heptacosylcyclohexane which strongly increases in abundance within the extinction interval of the end permian ecological crisis is here reported from the key permian triassic p tr marine section in greenland prior to this study this compound had been known from early triassic organic rich marine rocks and oils from the northern perth basin western australia for two decades we have identified the compound in high relative abundance in 29 samples from p tr marine sections from two separate paleogeographic localities from laurasia and gondwana relative concentrations of the c33 n alkylcyclohexane show similar changes to the relative abundances of extinct spinose acritarchs veryhachium and micrhystridium indicating that the source organism of the c33 n alkylcyclohexane is associated with the depositional environments facies in which the acritarchs are identified these organisms probably formed the cornerstone of the unique marine ecosystem that thrived in the extinction aftermath in the early triassic ocean

multidisciplinary high resolution correlation of the permian triassic boundary abstract biostratigraphic correlation of the ten most important permian triassic boundary sections throughout tethys enables establishment of four conodont and ammonoid subdivisions within a stratigraphic interval one to a few metres thick representing less than 1 ma in ascending order they are conodonts clarkina changxingensis c deflecta zone hindeodus typicalis interval isarcicella parva zone and i isarcica zone and ammonoids pseudotirolites pleuronodoceras zone lower otoceras zone upper otoceras zone and ophiceras zone most of them can be traced to north america and the arctic region carbon isotope investigations of 24 sections along tethys and in greenland and spitzbergen confirm the consistency of 13c negative excursions at the permian triassic boundary together with an inconsistent ir anomaly eight sections show that in most cases there is a succession of ir anomaly denoting the end permian catastrophic environment 13c excursion biomass loss extinction p t boundary origination of newcomers potentially capable of intercontinental correlation within that short time interval there is an intercontinental sequence boundary at the top of the permian and a transgressive surface at the p t boundary followed shortly by a maximum flooding surface an intercontinental anoxia event accompanied the transgression three delineations of the mass extinction phases and three population explosions have been recognized and can be more or less correlated in south china and the southern alps radiometric dating of the volcanogenic boundary clays of meishan shangsi and the main stage siberian tunguss traps give an almost identical age of 250 ma thus implying a synchronous interregional volcanic event there are a few palaeomagnetic transforms within the ptb strata thus multidisciplinary research of the p t boundary strata allows subdivision of this short interval into more than ten intercontinentally correlatable parts each subdivision averages less than 100 ka in duration this may be the highest resolution obtained so far in pre cretaceous rocks high frequency milankovitch type cyclic deposits within the p t boundary beds enable correlation of even higher resolution in the lower yangtze area this high resolution is made possible because the p t transition is a time of saltation and catastrophy in geological history causality of the aggregation of events merits further investigation

significance of polycyclic aromatic hydrocarbons pahs in permian triassic boundary sections abstract in this study the abundances of several polycyclic aromatic hydrocarbons pahs table 1 i xxi have been measured throughout three permian triassic p tr sections from meishan south china kap stosch area east greenland and peace river basin western canada dibenzothiophene i and dibenzofuran ii were found to decrease in abundance just before or shortly after the p tr transition in all three sections while perylene iii was observed to increase in abundance at the onset of the main extinction horizon bed 25 in meishan perylene has been attributed to a wood degrading fungal source and therefore it seems possible these phenomena are related to the demise of land plants further distinct patterns of various combustion derived pahs occurring in each section imply that forest fire events occurred within the late permian and early triassic in the meishan section high amounts of combustion derived pahs pyrene iv fluoranthene v benzo a anthracene vi benzofluoranthenes sum i e vii benzo a pyrene viii benzo e pyrene ix and coronene x occur within bed 25 also containing ash attributed to the fallout from massive volcanic eruptions in siberia and or china

intensified chemical weathering during the permian triassic transition recorded in terrestrial and marine successions abstract global warming is inferred to have been one of the main causes of the permian triassic p tr boundary mass extinction although a strong temperature rise in tropical sea surface temperatures during the latest permian has been documented coeval climate changes in terrestrial sections are less well known here we analyzed multiple weathering indexes including cia ciw and pia for two terrestrial sections in north china shichuanhe and yima all of which show a major excursion toward higher values greater weathering intensity around the end permian plant extinction eppe at shichuanhe the cia chemical index of alteration increases from 70 to 75 over the interval of 11 36 m which straddles the eppe at 33 m and then decreases from 75 to 71 in the overlying strata at yima cia increases from 63 to 79 over the interval of 57 68 m extending up to the eppe at 68 m and then gradually decreases from 78 to 72 in the overlying strata these results imply a strong warming event coupled with intense chemical weathering in soil environments leading up to the end permian plant extinction the decline in cia values following the eppe may reflect loss of weathered soils through physical erosion rather than climatic cooling estimation of atmospheric temperatures from the cia data indicate rapid rises at shichuanhe from 11 6 c to 16 5 c and yima from 9 3 c to 18 4 c during the end permian crisis the findings in this study are consistent with the hypothesis that a sharp temperature rise caused the extinction of terrestrial organisms during the end permian crisis

evidence for wildfire in the meishan section and implications for permian triassic events polynuclear aromatic hydrocarbons pahs and black carbon bc in sediments are powerful tools in the identification of the combustion process throughout geologic history in this study combustion derived pahs and bc were carefully investigated in sediments from the global stratotype section and point of the permian triassic p tr boundary in meishan china quantitative analyses of combustion derived pahs and bc demonstrate anomalously high concentrations in the boundary event beds that coincide with the mass extinction horizon the prevalence of parent polynuclear aromatics e g phenanthrene in pahs together with non metric multidimensional scaling analysis confirms that the pahs are mainly derived from vegetation burning instead of having a coal and or oil origin bc detected in sediment occurs in various forms from large irregular charcoal particles to fine aciniform soot with an equivalent reflectance of up to 3 5 the results strongly suggest that a wildfire occurred during the p tr boundary which served as one of the possible triggers of mass extinction on land the wildfire occurrence indicates that the o2 concentration of the atmosphere during or before the p tr mass extinction was probably 17 the temporal coincidence of the mass extinction with intensive volcanic eruption marine anoxia and wildfire events in the region of the meishan section provides new insight into the mechanisms of the p tr biotic crisis our results show that wildfires could have played an important role in the collapse of the ecosystem in the meishan p tr events

two episodes of environmental change at the permian triassic boundary of the gssp section meishan abstract high resolution stratigraphic records through the permian triassic boundary ptb interval of the global stratotype section and point gssp at meishan zhejiang province china reveal that the ptb crisis was not a single abrupt catastrophe a bed by bed analysis of environmental and biotic changes makes clear that the crisis can be resolved into two discrete episodes each consisting of three stages a unstably oscillating conditions b peak crisis conditions and c ameliorating conditions the first crisis episode commenced in bed 23 peaked in beds 24e 26 and ameliorated in beds 27 and 28 while the second crisis episode commenced in bed 29 peaked in beds 34 38 and ameliorated in beds 39 and higher the macroscopic mass extinctions happened not at the beginning nor the end of each cycle but at times when the crisis or perturbation of environments began these extinction events do not show detectable feedbacks to concurrent environmental changes in each episode cyanobacteria proliferation postdated the macroscopic extinction while proliferation of green sulfur bacteria predated the environmental crisis causational analysis between environmental and microbial changes show that geomicrobial functional groups exercised pronounced effects on the marine c n s cycles and ocean redox conditions during the ptb crisis it is possible thus that the microbial crises played an important role in strengthening or evening triggering the environmental crisis

pattern of marine mass extinction near the permian triassic boundary in south china the meishan section across the permian triassic boundary in south china is the most thoroughly investigated in the world a statistical analysis of the occurrences of 162 genera and 333 species confirms a sudden extinction event at 251 4 million years ago coincident with a dramatic depletion of 13ccarbonate and an increase in microspherules

expansion of photic zone euxinia during the permian triassic biotic crisis and its causes microbial biomarker records the incursion of euxinic waters into the ocean surface layer is hypothesized to have been an important killing agent during the end permian mass extinction however both the causes and extent of oceanic euxinia during this crisis remain poorly known making assessment of its role in the mass extinction difficult here we document the distribution of aryl isoprenoids ais which are biomarkers of obligate anaerobic green sulfur bacteria chlorobiaceae that are indicative of photic zone euxinia in 12 permian triassic boundary ptb sections with a wide distribution globally profiles of ai abundance for the 12 study sections show significant spatio temporal variation no ais were identified in the shallowest sections but ais are present both prior to and following the mass extinction in intermediate depth sections and following the mass extinction in deep water sections this pattern suggests a combination of upward and oceanward expansion of photic zone euxinia during the ptb crisis possibly fueled by elevated riverine nutrient fluxes as a consequence of climatic warming terrestrial ecosystem destruction and enhanced erosion this hypothesis is supported by the close association of ais with elevated abundances of moretanes and dibenzofuran dbf which are biomarkers for terrestrial erosion expansion of oceanic euxinia at intermediate water depths may have established a long term reservoir that fed episodic incursions of h2s bearing waters into shallow marine environments delaying the recovery of marine ecosystems during the early triassic the biomarker records of the present study thus provide significant evidence of terrestrial marine linkage during the ptb crisis

complete biotic and sedimentary records of the permian triassic transition from meishan section south china ecologically assessing mass extinction and its aftermath abstract the meishan section south china is the global stratotype section and point gssp for the permian triassic boundary ptb and is also well known for the best record demonstrating the permian triassic mass extinction ptme all over the world this section has also been studied using multidisciplinary approaches to reveal the possible causes for the greatest phanerozoic biocrisis of life on earth many important scenarios interpreting the great dying have been proposed on the basis of data from meishan nevertheless debates on biotic extinction patterns and possible killers still continue this paper reviews all fossil and sedimentary records from the permo triassic p tr transition based on previously published data and our newly obtained data from meishan and assesses ecologically the ptme and its aftermath to determine the biotic response to climatic and environmental extremes associated with the biocrisis eight updated conodont zones clarkina yini clarkina meishanensis hindeodus changxingensis clarkina taylorae hindeodus parvus isarcicella staeschei isarcicella isarcica and clarkina planata zones are proposed for the ptb beds at meishan major turnover in fossil fragment contents and ichnodiversity occurs across the boundary between bed 24e 5 and bed 24e 6 suggesting an extinction horizon in a thin stratigraphic interval the irregular surface in the middle of bed 27 is re interpreted as a firmground of glossifungites ichnofacies rather than the previously proposed submarine dissolution surface or hardground surface both fossil fragment contents and ichnodiversity underwent dramatic declines in beds 25 26a coinciding with metazoan mass extinction fossil fragment content ichnodiversity and all ichnofabric proxies including burrow size tiering level bioturbation level indicate that the p tr ecologic crisis comprises two discrete stages coinciding with the first and second phases of the ptme in meishan ecologic crisis lagged behind biodiversity decline during the ptme pyrite framboid size variations suggest that depositional redox condition was anoxic to euxinic in the latest changhsingian became euxinic in beds 25 26a turned dysoxic in bed 27 then varied from euxinic to anoxic through most of the griesbachian the 9 c increase in seawater surface temperature from bed 24e to bed 27 at meishan seems to result in dramatic declines in biodiversity and fossil fragment contents in beds 25 26a but had little effect on all ecologic proxies both metazoans and infauna seem not to have been affected by the pre extinction anoxic euxinic condition the anoxic event associated with the ptme may have occurred in a much shorter period than previously thought and is only recorded in beds 25 26a at meishan fossil fragment contents ichnofaunas ichnofabrics and pyrite framboid size all show that no signs of oceanic acidification and anoxia existed in bed 27 the early griesbachian anoxia may have resulted in rarity of ichnofauna and metazoans in the lower yinkeng formation in which the ichnofauna is characterized by small simple horizontal burrows of planolites and metazoan faunas are characterized by low diversity high abundance opportunist dominated communities the rapid increase of 9 c in sea surface temperature and a short anoxia or acidification coincided with the first pulse biocrisis while a prolonged and widespread anoxia probably due to a long period of high seawater temperate condition may be crucial in mortality of most organisms in the second pulse ptme marine ecosystems started to recover coupled with environmental amelioration in the late griesbachian

some aspects of the permian triassic boundary ptb and of the possible causes for the biotic crisis around this boundary abstract the first appearance datum fad of hindeodus parvus is an excellent datum very close to the base of the otoceras woodwardi zone priority base of the triassic for the first time it allows an exact correlation of the ptb in all marine facies and faunal realms the following features of the extinction and recovery patterns near the ptb are most important for the search for causes of the ptb biotic crisis 1 most strongly affected were the siliceous plankton radiolarians and the warm water benthos and nekton 2 most of the cold water faunas were not significantly affected 3 the recovery of the warm water benthos and siliceous plankton occurred only after an unusually long time during the late olenekian and middle triassic 4 the productivity of the terrestrial plants dropped strongly and the recovery was mainly in the upper olenekian and in the middle triassic 5 several terrestrial extinction events occurred at different levels within the upper permian considerable before the marine ptb at or close to the fad of lystrosaurus no extinction event in the terrestrial faunas can be observed 6 terrestrial faunal elements that survived the dzhulfian dorashamian extinctions were able to survive some months of extreme climatic conditions by hibernation like life stages vertebrates or by dry and freezing resistant eggs conchostracans 7 about 50 of the genera that disappeared at the ptb re appeared in the olenekian middle triassic interval lazarus taxa or in this time interval genera appeared that had undoubtedly evolved from genera that had disappeared at the ptb and 8 the ptb is preceded by mass occurrences of marine and continental fungi and the fungal spike ends abruptly a little before the ptb a scenario for the ptb biotic crisis is elaborated that takes into consideration the real not interpolated diversity patterns of different marine and continental fossil groups the exact correlation of bioevents in different faunal realms and facies the strong biotic crisis in the tethyan warm water faunas in contrast to the much weaker biotic event in cold water faunas the severe dzhulfian dorashamian climate in many parts of the world caused by the continent ocean configuration and by siberian trap volcanism the cooling of the boreal area by the northward drift of pangaea that interrupted the exchange of warm water benthos between the tethys and western north america during the guadalupian the extinction event at the guadalupian lopingian boundary that restricted most of the affected warm water faunas to the tethys the importance of lower scythian anoxia that reached an unusually shallow level and above all the effects of the contemporaneous huge volcanic events about 250 m y ago on the siberian platform and in the eastern tethys that caused a 3 6 months lasting volcanic winter with strong cooling in low latitudes followed by a strong global warming

catastrophic soil erosion during the end permian biotic crisis organic geochemical analyses of sedimentary organic matter from a marine permian triassic transition sequence in northeastern italy reveal a significant influx of land derived diagenetic products of polysaccharides this unique event reflects massive soil erosion resulting from destruction of land vegetation due to volcanogenic disturbance of atmospheric chemistry the excessive supply of soil materials to the oceans provides a direct link between terrestrial and marine ecological crises suggesting that ecosystem collapse on land could have contributed to the end permian marine extinctions

measurements of snow and glacier covered areas with single polarization sar climatological and hydrological investigations in mountainous regions frequently require delineation of the areas covered by snow and glacial ice active microwave sensors can discriminate snow and glacier from other targets are effective under all weather conditions and have a spatial resolution compatible with the topographic variation in alpine regions using data acquired with the nasa airsar which operates at three frequencies and four combinations of polarization we examine the usage of synthetic aperture radar sar to map snow and glacier covered areas in order to assess the available sars that operate from satellites we analyze single frequency single polarization data and we compare our results with images from the landsat thematic mapper obtained under clear conditions only a few days after the sar flight single polarization c band 5 3 ghz sar data can discriminate between areas covered by wet snow from those that are ice free but do not easily separate glacier ice from snow and rock l band sar 1 25 ghz data cannot discriminate between snow and glacier ice the accuracy 74 of sar is high enough to justify its use as the data source in areas that are too cloud covered to obtain reliable data from the thematic mapper

gradual onset of anoxia across the permian triassic boundary in svalbard norway the permian triassic extinction event is considered to be the most devastating environmental crisis of the phanerozoic with many coinciding factors involved the role of marine anoxia during the extinction is still poorly understood in this study a boreal permian triassic boundary ptb section from svalbard norway has been investigated with the aim of better understanding the timing and nature of local marine anoxia onset and extinction events across the ptb the section comprises the kapp starostin and vikinghogda formations 13corg values indicate the ptb is located within the lower part of the vikinghogda formation lag deposits at the top of the kapp starostin formation indicate a marine hiatus and ensuing transgression during the late permian shortly before the extinction event implying concurrence of major ecological changes and sea level rise pyrite framboid size distributions and total organic carbon toc were used to evaluate bottom water oxygen conditions and show that changes in bottom water redox conditions and extinction are clearly linked oxic to dysoxic bottom water conditions prevailed during deposition of kapp starostin formation sediments and changed to anoxic to euxinic conditions above the formation boundary the onset of anoxia is not abrupt but rather shows a gradual increase within the kapp starostin formation during the late permian the tipping point where bottom waters reach a long term state of anoxia to euxinia coincides with the final extinction event though changes in biotic assemblages at the top of the kapp starostin formation indicate a marine ecosystem crisis prior to this oxygen depletion in the boreal region as seen in our study section and correlating to greenland and arctic canada seems to be consistently more severe than in lower latitude settings

stepwise and large magnitude negative shift in δ13ccarb preceded the main marine mass extinction of the permian triassic crisis interval abstract large perturbations to the global carbon cycle occurred during the permian triassic boundary mass extinction the largest extinction event of the phanerozoic eon 542 ma to present controversy concerning the pattern and mechanism of variations in the marine carbonate carbon isotope record of the permian triassic crisis interval ptci and their relationship to the marine mass extinction has not been resolved to date herein high resolution carbonate carbon isotope profiles 13ccarb accompanied by lithofacies were generated for four sections with microbialite taiping zuodeng cili and chongyang in south china to better constrain patterns and controls on 13ccarb variation in the ptci and to test hypotheses about the temporal relationship between perturbations to the global carbon cycle and the marine mass extinction event all four study sections exhibit a stepwise negative shift in 13ccarb during the late permian early triassic with the shift preceding the end permian crisis being larger 3 than that following it 1 2 the pre crisis shifts in 13ccarb are widely correlatable and hence represent perturbations to the global carbon cycle the comparatively smaller shifts following the crisis demonstrate that the marine mass extinction event itself had at most limited influence on the global carbon cycle and that both late permian 13ccarb shifts and the mass extinction must be attributed to some other cause their origin cannot be uniquely determined from c isotopic data alone but appears to be most compatible with a mechanism based on episodic volcanism in combination with collapse of terrestrial ecosystems and soil erosion

sudden changes in fluvial style across the permian triassic boundary in the eastern iberian ranges spain analysis of possible causes abstract the sedimentary record of the late permian and early triassic of the eastern iberian ranges shows four major sudden or very rapid vertical changes in fluvial style the late permian sedimentary cycle starts with the boniches formation of alluvial fan braided fluvial origin which grades vertically over within a few metres into the alcotas formation deposited by low to high sinuosity avulsion prone rivers with extensive floodplains the alcotas formation contains calcimorphic soils plant remains and pollen and spore assemblages however the upper third of the unit is devoid of all organic remains and soils and is characterized by a dominant red colour the sandstone levels were deposited by high sinuosity meandering rivers this major change took place during the late permian and is probably coeval with the emplacement of the emeishan basaltic large igneous province lip in se china rocks of the boniches and alcotas formations are separated by an angular unconformity from the overlying strata which consist of the late permian conglomeratic hoz del gallo formation of alluvial fan gravel braided fluvial origin and the sandy canizar formation of low sinuosity sandy river origin the permian triassic boundary lies probably between the upper part of the hoz del gallo formation and the first metres of the canizar formation late permian pollen and spore assemblages have been found in the hoz del gallo formation but the canizar formation is barren with the exception of an anisian middle triassic assemblage at the top tectonic extensional pulses in the iberian basin caused the changes observed between the lower and upper parts of the boniches formation at the base of the hoz del gallo formation and between the lower and upper part of this formation the changes observed in the uppermost part of the alcotas formation are not easily explained by tectonic causes nor those in the passage from the hoz del gallo formation to the canizar formation similar sedimentary characteristics of the sandy canizar formation such as amalgamated sandstone bodies erosion and reactivation surfaces dominant trough cross stratification tabular geometry absence of plant remains and pollen and spores and absence of silts and clays to those of coeval formations in places as far away as australia south africa and brazil suggest a global rather than local cause for these abrupt changes in fluvial style this global cause was probably die off of plant cover over extensive areas of the catchment related to the end of the permian mass extinction and possibly related to the emplacement of the west siberian basaltic large igneous province lip responsible for drastic atmospheric and marine changes

eclogites preserved as pebbles in jurassic conglomerate dabie mountains china abstract two types of eclogite pebbles were discovered in middle to upper jurassic conglomerates from the hefei basin north of the dabie ultrahigh pressure uhp terrain china type a eclogite pebbles are characterized by idioblastic garnet with well preserved chemical zonation si content in phengite is lower than 3 5 per formula unit pfu the maximum metamorphic pressure is lower than 2 5 gpa and the temperature is below 600 c type b eclogite pebbles contain coesite pseudomorphs in xenoblastic garnet si content in phengite is higher than 3 5 pfu the maximum metamorphic pressure is 2 8 4 0 gpa at 700 c indicating uhp metamorphism types a and b eclogite pebbles are comparable with eclogites occurring in the southern portion of the dabie uhp terrain based on the petrologic similarities and northeastwards directed paleocurrents we infer that the eclogite pebbles were eroded from the dabie uhp terrain sandstones containing detrital phengite with si content higher than 3 5 pfu are also derived from uhp rocks these petrologic and stratigraphic data place time constraints on exhumation and erosion history of the dabie uhp terrain

chemical constitution of a permian triassic disaster species one of the most controversial biological proxies of environmental crisis at the close of the permian is the organic microfossil reduviasporonites the proliferation of this disaster species coincides with the mass extinction and numerous geochemical disturbances originally reduviasporonites was assigned to fungi opportunistically exploiting dying end permian forests but subsequent geochemical data have been used to suggest an algal origin we have used high sensitivity equipment partly designed to detect interstellar grains in meteorites to reexamine the geochemical signature of reduviasporonites organic chemistry carbon and nitrogen isotopes and carbon nitrogen ratios are consistent with a fungal origin the use of this microfossil as a marker of terrestrial ecosystem collapse should not be merely discounted unequivocally diagnostic data however may have been precluded by post burial replacement of its organic constituents

the timing and pattern of biotic recovery following the end permian mass extinction the aftermath of the great end permian period mass extinction 252 myr ago shows how life can recover from the loss of 90 species globally the crisis was triggered by a number of physical environmental shocks global warming acid rain ocean acidification and ocean anoxia and some of these were repeated over the next 5 6 myr ammonoids and some other groups diversified rapidly within 1 3 myr but extinctions continued through the early triassic period triassic ecosystems were rebuilt stepwise from low to high trophic levels through the early to middle triassic and a stable complex ecosystem did not re emerge until the beginning of the middle triassic 8 9 myr after the crisis a positive aspect of the recovery was the emergence of entirely new groups such as marine reptiles and decapod crustaceans as well as new tetrapods on land including eventually dinosaurs the stepwise recovery of life in the triassic could have been delayed either by biotic drivers complex multispecies interactions or physical perturbations or a combination of both this is an example of the wider debate about the relative roles of intrinsic and extrinsic drivers of large scale evolution from a much more devastated planet and biota than the others with only some 10 of species surviving the epme was much harsher than the other mass extinctions during which global species diversity reduced to only about 50 of the pre extinction total 1 2 24 26 this means that the triassic recovery has two profound implications first it may show qualitative as well as quantitative differences from the other post extinction recoveries and second it can act as an exemplar of what to expect at its most extreme when global biodiversity is pushed to the brink there are obvious implications for current concerns about biodiversity loss and recovery resulting from human impacts 27 28 in the past ten years attention has focused on the sedimentary successions in south china these are enormously laterally extensive with some formations extending more than 2 000 km from the zhejiang to yunnan provinces the huge exposures length of the sections and improving dating open up the opportunity to explore physical environmental and biotic changes through the extinction and recovery times in varied marine habitats and compare these with patterns elsewhere in the world fig 1 a fine scale forensic analysis of this extraordinary time in earth s history now becomes possible the end permian mass extinction the epme killed 80 96 of marine animal species and 70 of terrestrial vertebrate species

photic zone euxinia during the permian triassic superanoxic event carbon and sulfur isotopic data together with biomarker and iron speciation analyses of the hovea 3 core that was drilled in the perth basin western australia indicate that euxinic conditions prevailed in the paleowater column during the permian triassic superanoxic event biomarkers diagnostic for anoxygenic photosynthesis by chlorobiaceae are particularly abundant at the boundary and into the early triassic similar conditions prevailed in the contemporaneous seas off south china our evidence for widespread photiczone euxinic conditions suggests that sulfide toxicity was a driver of the extinction and a factor in the protracted recovery

sm nd geochronology and petrography of garnet pyroxene granulites in the northern sulu region of china and their geotectonic implication abstract abundant garnet bearing granulite lenses are widely distributed in the northern part of the sulu region and adjacent areas they are possibly re metamorphosed high pressure metamorphic rocks on the basis of detailed petrographic study samples wd01 wd04 and ml06 from laixi and wendeng were identified as high pressure granulites and wh1 from weihai as an original coesite bearing eclogite three high pressure granulite samples give mineral wr isochron ages of 1846 76 1743 79 and 1752 30 ma tdm ages are 3 3 3 0 and 2 8 ga the sm nd mineral wr isochron ages are interpreted to date as the metamorphic resetting within the medium pressure granulite facies representing an isotopic re homogeneity during uplifting of the high pressure granulites from deep continent crust it is important that sm nd chronological characteristics are the same as archaean high pressure granulites in the north china craton however sample wh1 from weihai demonstrates abnormal sm nd characteristics its whole rock end 0 value is 129 tdm age is 1 3 ga and constrains the minimum age of re metamorphosed eclogite protolith formation to the mid proterozoic this result is identical to those reported by jahn 1994 showing complicated processes of metamorphism and metasomatism the data in this paper provide further evidence to define the boundary between the north china craton and uhpm belt in eastern shandong and to understand the geotectonic nature of the boundary

anomalous hopane distributions at the permian triassic boundary meishan china evidence for the end permian marine ecosystem collapse abstract molecular and carbon isotopic geochemistry of hopanes in marine sediments of the meishan section in changxing county zhejiang province of china were studied to reveal biotic and environmental changes across the permian triassic boundary ptb and the wuchiapingian changhsingian boundary wcb the hopane distribution at the ptb is characterized by high ratios of moretane hopane tm ts tm c 30 hopane c 31 c 32 hopane and hopane sterane this hopane distribution is anomalous for these marine sediments but it is typical of coal measure strata and soils two possible genetic mechanisms for such an anomaly are suggested 1 these hopanes were terrigenous and most probably originated from acidified soil and peat this mechanism implies that the marine primary production and aerobic bacteria production at the ptb were extremely low 2 this hopane distribution was possibly caused by freshening and acidification of the upper water column during the end permian to early triassic marine stagnation and stratification this hopane anomaly which coincides with the end permian mass extinction and carbon isotope excursion may signal the end permian mass extinctions and marine and terrigenous ecosystem collapse the 13 c enriched hopanes with the fingerprint of typical anoxic marine shales coupled with an n c 15 n c 17 dominated distribution of n alkanes strongly indicate that the organic matter around the wcb at meishan originated mainly from cyanobacteria the corresponding positive 13 c carbonate and higher total organic carbon and hydrocarbon index hi values strongly suggest that high marine primary production and marine anoxia caused by intermittent cyanobacterial blooms resulted in the local mass extinction at meishan

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

biogeochemical evidence for euxinic oceans and ecological disturbance presaging the end permian mass extinction event article i nfo the permian triassic boundary event at 252 2 ma marks the largest extinction of marine fauna in the phanerozoic and there is a wide consensus that the extinction coincided with an intense oceanic anoxic event thestratotypeofthechanghsingianstage preciselyconstrainedbytheptbglobalstratotypesectionandpoint gssp and the gssp for the wuchiapingian changhsingian boundary both at meishan in southern china is well documented in respect to geochronology and the pattern of extinction here we report secular trends in bulk isotopic parameters and lipid biomarkers in a core spanning 214 m of stratigraphic section across the ptb and through the entire changhsingian interval our analysis of these data viewed in the context of relative sea level change and strontium isotopes reveals distinct shifts in paleoenvironmental conditions and profound changes in plankton ecology well before and following the biological extinction event specifically patterns of steroids and triterpenoids indicate a marine plankton community that was heavily dominated by bacteria during the late wuchiapingian middle changhsingian and early griesbachian stages secular trends in aromatic hydrocarbons diagnostic for anoxygenic green sulphur bacteria chlorobiaceae identify periods when euxinic conditions extended into the photic zone during the entire changhsingian stage here also the 15

oxygen containing aromatic compounds in a late permian sediment in northern italy the base of the tesero oolite horizon represents the lithological boundary between the bellerophon and werfen formations and marks one of the most dramatic environmental perturbations in phanerozoic time the marl which directly underlies the tesero horizon contains many indicators of environmental change during the end permian mass extinction at vigo meano near trento the marl is relatively thermally immature and contains abundant terrestrially sourced oxygen containing aromatic compounds such as xanthones dibenzofurans and dibenzo p dioxin as well as abundant alkylated naphthalenes

strontium isotope evolution of late permian and triassic seawater the 87sr 86sr values based on brachiopods and conodonts define a nearly continuous record for the late permian and triassic intervals minor gaps in measurements exist only for the uppermost brahmanian lower part of the upper olenekian and middle norian and only sparse data are available for the late permian these 219 measurements include 67 brachiopods and 114 conodont samples from the tethyan realm as well as 37 brachiopods and one conodont sample from the mid european middle triassic muschelkalk sea the late permian lower triassic interval is characterized by a steep 1 3 10 3 rise from 0 7070 at the base of the dzhulfian to 0 7082 in the late olenekian a rate of change comparable to that in the cenozoic in the mid triassic anisian and ladinian the isotope values fall to 0 7075 followed again by a rise to 0 7081 in the middle late norian the 87sr 86sr values decline again in the late norian sevatian and rhaetian to 0 7076 the sharp rise in the 87sr 86sr values during the late permian early triassic was coincident with widespread clastic sedimentation because of the paucity of tectonic uplifts the enhanced erosion may have been due to intermittent humid phases during mainly an arid interval coupled with the absence of a dense protective land plant cover following the mass extinction during the latest permian the apex of the 87sr 86sr curve at the olenekian anisian boundary coincides with cessation of the large scale clastic sedimentation and also marks the final recovery of land vegetation as indicated by the renewed onset of coal formation in the middle triassic the rising 87sr 86sr values from the middle carnian to the late norian coincide with the uplift and erosion of the cimmeride indosinian orogens marking the closure of the palaeotethys the subsequent rhaetian decline that continues into jurassic pliensbachian toarcian boundary on the other hand coincides with the opening of the vardar ocean and its eastern continuation in the izmir ankara ophiolitic belt samples from the upper muschelkalk are more radiogenic than the global trend this may reflect separation of the basin from the open ocean due to strong meteoric influx from a large land mass in the north the germanic basin became increasing brackish up section in the north and east but because of the high evaporation rates the salt content was not much reduced in the southern and central basin where a rich but increasingly endemic marine fauna survived

exhumation tectonics of the ultrahigh pressure metamorphic rocks in the qinling orogen in east china new petrological structural radiometric insights from the shandong peninsula 1 in eastern china the sulu area is recognized as the eastern extension of the qinling dabie belt which is famous for its ultrahigh pressure uhp metamorphism although numerous petrologic and geochemical works are available structural data are still rare this paper provides the first extensive study of bulk geometry and kinematic analysis of the shandong peninsula the study area is divided into three tectonic areas by cretaceous faults namely a southern uhp belt or sulu area a northern migmatite area and an eastern eclogite and migmatite area or weihai area conversely to the deeply entrenched idea that the later area belongs to the north china belt and the two others to the south china block scb we argue that all three areas are parts of the scb structural petrologic 40ar 39ar and u pb data comply with this new interpretation in the north shandong area mafic granulites enclosed as blocks within gneissic migmatites do not significantly differ from the sulu and weihai eclogites which also experienced a granulite facies overprint before migmatization the circa 210 200 ma age of the main ductile deformation is related to an extensional event during the triassic or indosinian orogeny this date corresponds to the temperature climax but the time of the pressure peak i e the real age of the uhp metamorphism is discussed

discrimination of glacier facies using multi temporal sar data glacier facies from the greenland ice sheet and the wrangell st elias mountains alaska are analyzed using multi temporal synthetic aperture radar sar data from the european space agency ers 1 satellite distinct zones and facies are visible in multi temporal sar data including the dry snow facies the combined percolation and wet snow facies the ice facies transient melt areas and moraine in greenland and south central alaska very similar multi temporal signatures are evident for the same facies although these facies are found at lower altitude in west greenland where the equilibrium line appears to be found at sea level at 71 30 n during the year analyzed 1992 93 probably because of the cooling effect of the eruption of mount pinatubo in greenland both the percolation and dry snow facies are excellent distributed targets for sensor calibration with backscatter coefficients stable to within 0 2 db however the percolation facies near the top of mount wrangell are more complex and less easily delineated than in greenland and at high altitude the glacier facies have a multi temporal signature which depends sensitively on slope orientation