permian and triassic greenhouse crises paleoclimatic time series from permian and triassic paleosols reveal transient episodes of unusually warm and wet conditions interrupting long periods of cool and dry conditions usual for calcareous red paleosols some of these paleoclimatic events are known from stomatal index of fossil lepidopteris leaves to have been episodes of elevated global atmospheric co2 the magnitude of 19 known permian and triassic greenhouse crises varied considerably and they offer new evidence for the relationship between paleoclimate and atmospheric co2 levels these greenhouse crises also had marked effects on global lowland vegetation introducing frost sensitive tropical lycopsids to high latitudes and drought tolerant conifers to low latitude lowlands greenhouse events punctuate phases in plant evolution ottokaria callipteris plumsteadia rufloria lidgettonia tatarina pleuromeia and dicroidium scytophyllum floras greenhouse events also punctuate the evolution of reptilian dynasties successive pelycosaur dinocephalian dicynodont rhynchosaur and dinosaur faunas and respiratory adaptations such as enlarged bony secondary palate greenhouse crises of the late and middle permian were the most severe known and suggest a role for atmospheric pollution with ch4 and co2 in those mass extinction events probably from thermogenic cracking of coals by intrusive feeder dikes of flood basalts because of formalities in boundary definition these mass extinctions are neither end permian nor end guadalupian but upper changhsingian and mid capitanian respectively

soil organic carbon quantity chemistry and thermal stability in a mountainous landscape a rock eval pyrolysis survey mountain soils store huge amounts of carbon which may be highly vulnerable to the strong land use and climate changes that mountain areas currently experience worldwide here we tested the rock eval re pyrolysis as a proxy technique to i quantify soil organic carbon soc stocks ii bring insights into soc bulk chemistry and iii investigate biogeochemical stability at the landscape scale in a mountain area of the french calcareous prealps a total of 109 soils from 11 eco units representing the variety of ecosystems of the study area were analyzed with re pyrolysis re pyrolysis showed an excellent predictive performance r2 0 99 for soc content even in calcareous soils the technique revealed specific chemical fingerprints for some eco units and soil types with decreasing hydrogen index values from anthroposols 425 62 mg hc g soc to umbrisols leptosols 311 49 mg hc g soc and to cambisols 278 35 mg hc g soc associated with an increase in soc maturation newly developed re pyrolysis indices revealed the high stability of soc in most eco units developed on cambisols acidic grasslands alpine meadows bushy facies and a significantly lower stability of soc in mountain ridges sheepfold areas and coniferous forest soils the persistence of soc in this mosaic of ecosystems may depend not only on its chemistry or thermal stability but also on local environmental factors such as climatic conditions or ph especially for high altitude soils overall re pyrolysis appears as an appropriate tool for landscape scale carbon inventories and could become a standardized proxy for assessing the vulnerability of soc stocks

permian sedimentary record of the turpan hami basin and adjacent regions northwest china constraints on postamalgamation tectonic evolution the permian marks an important yet poorly understood tectonic transition in the tian shan region of northwestern china between devonian carboniferous continental amalgamation and recurrent mesozoic cenozoic intracontinental orogenic reactivation the turpan hami basin accommodated up to 3000 m of sediment and is ideally positioned to provide constraints on this transition new stratigraphic data and mapping indicate that extension dominated early permian tectonics in the region whereas flexural foreland subsidence controlled late permian basin evolution lower permian strata in the northwestern turpan hami basin consist of coarse grained debris flow and alluvial fan deposits interbedded with mafic to intermediate volcanic sills and flows in contrast lower permian rocks in the north central and northeastern turpan hami basin unconformably overlie a late carboniferous volcanic arc sequence these lower permian strata include possible shallow marine carbonate rocks and thick volcanic and volcaniclastic rocks that are in turn overlain by littoral to profundal lacustrine facies above a regional lower permian upper permian unconformity regional sedimentation patterns record the development of a more integrated sedimentary basin the upper permian is entirely nonmarine and can be correlated east west along the depositional strike of the basin the lower upper permian consists of a broad belt of braided fluvial deposits shed northward these strata are overlain by fluctuating littoral and profundal lacustrine facies and associated fluvial facies the uppermost permian is characterized by shallow lake plain and fluvial environments the early permian association of diffuse volcanism and partitioning of subbasins by normal faulting is consistent with an early phase of lithospheric extension local relationships indicate west east extension in the turpan hami basin along faults oriented normal to late devonian carboniferous collisional sutures within the tian shan the cause of extension in the wake of carboniferous orogenesis remains enigmatic however the temporal and spatial relationships of the two strain regimes suggest that they are genetically related upper permian stratigraphy and unconformities and local late permian triassic contractional deformation record foreland basin development when the turpan hami region became a wedge top basin with respect to the north tian shan fold and thrust belt flexurally induced late permian subsidence is also manifested in the larger junggar basin to the north where 4000 m of strata are preserved in the foredeep region the turpan hami and junggar basins were depositionally connected for much of the late permian when a vast lacustrine system developed across northwestern china this lacustrine paleogeography was only occasionally interrupted possibly by structural damming during uplift of the orogenic wedge

climate simulation of the latest permian implications for mass extinction life at the permian triassic boundary ca 251 ma underwent the largest disruption in earth s history paleoclimatic data indicate that earth was significantly warmer than present and that much of the ocean was anoxic or euxinic for an extended period of time we present results from the first fully coupled comprehensive climate model using paleo geography for this time period the coupled climate system model simulates warm high latitude surface air temperatures related to elevated carbon dioxide levels and a stagnate global ocean circulation in concert with paleodata indicating low oxygen levels at ocean depth this is the first climate simulation that captures these observed features of this time period

multiple early triassic greenhouse crises impeded recovery from late permian mass extinction the late permian mass extinction was not only the most catastrophic known loss of biodiversity but was followed by unusually prolonged recovery through the early triassic opinion has been divided on whether delayed recovery was a legacy of especially profound ecological disruption or due to additional environmental perturbations new records from the sydney basin in southeastern australia now reveal five successive late permian and early triassic spikes of unusually high atmospheric co2 and profound chemical weathering these successive atmospheric co2 greenhouse crises coincided with unusually warm and wet paleoclimates for a paleolatitude of 61 s successive transient greenhouse crises punctuated long term cool dry and low co2 conditions and may account for the persistence of low diversity and small size in early triassic plants and animals

the early carboniferous courceyan arundian monsoonal climate of the british isles evidence from growth rings in fossil woods the british isles lay at a palaeolatitude of 4 s during the early carboniferous courceyan arundian period this paper examines fossil gymnosperm wood from ten localities in western ireland and southern scotland in order to analyse palaeoclimate fifty two percent of the 77 fossil wood specimens studied exhibit growth rings that possess subtle discontinuous ring boundaries and ring increments of narrow but variable width these growth rings are qualitatively and quantitatively analysed and are shown to bear a close similarity to growth rings in modern araucarian conifer woods these araucarian growth rings are formed in response to tropical rainfall seasonality linked to monsoonal circulation the findings of this study therefore support earlier palaeoclimatic interpretations based on sedimentological evidence which suggest that the british isles experienced a monsoonal climate during the early carboniferous courceyan arundian period

first report of permineralised plants in the stephanian of arnao asturias northwestern spain abstract the first record of an anatomically preserved flora from stephanian outcrops at arnao beach asturias spain is presented the stratigraphic section is part of a geological heritage site that preserves exceptional devonian reef deposits the carboniferous succession contains coal seams worked by one of the earliest mines in spain and its plant fossil assemblages were reported in the 19th century but scarcely revised later the new assemblages recovered in the beach during extreme low tides represent the first record of permineralised trunks in northwestern spain large cordaitalean specimens are referred to a new species of cordaixylon characterised by non septate pith araucarian radial pitting of the tracheids and cross fields with phyllocladoid pits part of the root mantle of psaronius is preserved in water worn pebbles indicating the presence of tree ferns in the palaeoflora the associated compression impression assemblage includes lycophytes sphenophytes pteridosperms and pteridophytes a comparison of the assemblage confirms its importance for reconstructing the late pennsylvanian floral succession in the region

holocene climate variability as reflected by mid european lake level fluctuations and its probable impact on prehistoric human settlements abstract a data set of 180 radiocarbon tree ring and archaeological dates obtained from sediment sequences of 26 lakes in the jura mountains the northern french pre alps and the swiss plateau was used to construct a holocene mid european lake level record the dates do not indicate a random distribution over the holocene but form clusters suggesting an alternation of lower and higher climatically driven lake level phases they provide evidence of a rather unstable holocene climate punctuated by 15 phases of higher lake level 11 250 11 050 10 300 10 000 9550 9150 8300 8050 7550 7250 6350 5900 5650 5200 4850 4800 4150 3950 3500 3100 2750 2350 1800 1700 1300 1100 750 650 cal bp and after 1394 ad a comparison of this mid european lake level record with the gisp2 polar circulation index pci record the north atlantic ice rafting debris ird events and the 14 c record suggests teleconnections in a complex cryosphere ocean atmosphere system correlations between the gisp2 pci the mid european lake level the north atlantic ird and the residual 14 c records suggest that changes in the solar activity played a major role in holocene climate oscillations over the north atlantic area

using rock eval 6 pyrolysis for tracking fossil organic carbon in modern environments implications for the roles of erosion and weathering this work relates to the debate on the fossil organic carbon foc input in modern environments and its possible implication for the carbon cycle and suggests the use of rock eval 6 pyrolysis as a relevant tool for tracking foc in such environments considering that such a delivery is mainly due to supergene processes affecting the continental surface we studied organic matter in different reservoirs such as bedrocks alterites soils and rivers in two experimental catchments at draix alpes de haute provence france samples were subjected to geochemical rock eval 6 pyrolysis investigations and artificial bacterial degradations after comparing the geochemical fingerprint of samples geochemical markers of foc were defined and tracked in the different reservoirs our results confirm the contribution of foc in modern soils and rivers and display the various influences of weathering and erosional processes on the fate of foc during its exchange between these pools in addition the contrasting behaviour of these markers upon the supergene processes has also highlighted the refractory or labile characters of the fossil organic matter fom bedrock to river fluxes controlled by gully erosion are characterized by a qualitative and quantitative preservation of fom bedrock to alterite fluxes governed by chemical weathering are characterized by foc mineralization without qualitative changes in deeper alterites alterite to soils fluxes controlled by bio chemical weathering are characterized by strong foc mineralization and qualitative changes of fom thus weathering and erosional processes induce different fom evolution and affect the fate of foc towards the global carbon cycle in this study gully erosion would involve maintenance of an ancient sink for the global carbon cycle while bio chemical processes provide a source of co2 finally this study suggests that rock eval 6 pyrolysis can be considered as a relevant tool for tracking foc in modern environments copyright 2006 john wiley sons ltd

paleophysiology and end permian mass extinction physiological research aimed at understanding current global change provides a basis for evaluating selective survivorship associated with permo triassic mass extinction comparative physiology links paleontological and paleoenvironmental observations supporting the hypothesis that an end permian trigger most likely siberian trap volcanism touched off a set of physically linked perturbations that acted synergistically to disrupt the metabolisms of latest permian organisms global warming anoxia and toxic sulfide probably all contributed to end permian mass mortality but hypercapnia physiological effects of elevated pco2 best accounts for the selective survival of marine invertebrates paleophysiological perspectives further suggest that persistent or recurring hypercapnia global warmth also played a principal role in delayed triassic recovery more generally physiology provides an important way of paleobiological knowing in the age of earth system science 2007 elsevier b v all rights reserved

sedimentary evidence of early late permian mid latitude continental climate variability southern bogda mountains nw china abstract a preliminary early late permian mid latitude continental climatic record in nw china was interpreted mainly from sedimentary climate indicators and type and stacking pattern of depositional systems and cycles in a 1178 m fluvial lacustrine section depositional systems analysis delineated five types of primary fluvial and lacustrine depositional cycles which were grouped into three high intermediate and low orders semi arid subhumid and humid climate types in terms of relative precipitation evaporation ratio were interpreted and climate variability was identified at sub cycle and high intermediate and low order cycle scales early kungurian climate fluctuated between subhumid to humid and middle late kungurian climate shifted gradually from subhumid semi arid to semi arid roadian climate fluctuated widely from humid to semi arid with strong precipitation seasonality at sub cycle and high order cycle scales wordian climate was dominantly humid with short subhumid intervals and ended with a peak semi arid condition capitanian climate was mainly subhumid to humid as the start of a long interval of dominantly humid strongly wet dry conditions into the wuchiapingian time the late kungurian wordian semi arid condition is incompatible with modern mid latitude east coast humid climate suggesting different mechanisms operating in pangea and panthalassa the highly variable roadian wordian climate may have started terrestrial mass extinction that climaxed at the end of permian

pattern of vertebrate extinctions across an event bed at the permian triassic boundary in the karoo basin of south africa the extinction of vertebrates around the time of the permian triassic boundary has long been regarded as a gradual event occurring over millions of years our new field investigations of fluvial strata in the central and southern karoo basin of south africa have revealed the presence of an event bed coinciding with a mass extinction of terrestrial fauna and flora the bed is in a sedimentary sequence that is marked by a reddening of flood plain mud rocks and a change from high to low sinuosity river channel systems here we show that the pattern of vertebrate taxa disappearing below this boundary and the subsequent appearance of new taxa above the boundary are consistent with a relatively sudden possibly catastrophic event perhaps of 50 000 yr duration or less

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

integrated provenance analysis of a complex orogenic terrane mesozoic uplift of the bogda shan and inception of the turpan hami basin nw china we employ petrographic and advanced geochemical tech niques to better document the evolution of the turpan hami basin based on the unique geologic histories of the arc terranes that served as potential sources of turpan hami deposits first a provenance study of permian through cretaceous sandstone of the turpan hami basin reveals temporal and spatial changes in dominant source ter ranes that provided detritus to the basin volcanic lithic rich upper permian sandstone mean qm 19f18lt63 q p 7lvm89lsm4 q m 48p39k13 followed by more quartzose compositions in triassic sandstone mean qm 41f19lt40 q p 20lvm75lsm5 q m 68p21k11 indicate progressive un roofing of the extinct northern and central tian shan arc terranes to the south of turpan hami a sharp change to sedimentary lithic rich lower jurassic sandstone mean qm 47f16lt37 q p 16lvm42lsm42 qm 75p12k13 overlain by a return to volcanic lithic rich middle ju rassic sandstone mean qm 39f21lt40 q p 14lvm51lsm35 q m 65p21k14 points to the initial uplift and unroofing of the largely andesitic bogda shan to the north which first shed its sedimentary cover as it emerged to become the partition between the turpan hami and southern jung gar basins second geochronological trace element and sm nd isotopic varia tions among granitoids in the late paleozoic tian shan orogenic belt provide a further test of mesozoic uplift of the bogda shan on the basis of previous models of crustal compositions throughout the south central and north tian shan bogda shan and east and west jung gar terranes we infer that isotopically enriched granitic cobbles av erage endi 5 20 50 n 5 6 contained in lower triassic deposits in the north central turpan hami basin were derived from the continen tal crustal central tian shan terrane south of turpan hami and not from the more oceanic north tian shan bogda shan and east and west junggar terranes north of the turpan hami basin we therefore infer that the ancestral bogda shan had not been uplifted by the early triassic and that prior to this time a unified junggar turpan hami basin existed during late permian deposition of extensive lacustrine deposits

climate variations in europe over the past 140 kyr deduced from rock magnetism rapid shifts in climate during the last glacial are now well documented particularly from the oxygen isotope records of the two greenland ice cores grip1 2 and gisp23 in the grip record1 2 these climate events are also seen during the preceding eemian interglacial which may be an analogue for the future climate warmed by the greenhouse effect but these shifts are not found in the eemian section of the gisp2 core3 casting doubt on whether the rapid shifts in the grip oxygen isotope record really do represent a climate signal here we present magnetic susceptibility pollen and organic carbon records from maar lake deposits in the massif central france these data provide an independent record of past climate and we find that they correlate well with the ice core records during the last glacial during the eemian two rapid cooling events seen in our record also correlate with those seen in the grip ice core supporting the idea that rapid climate change did occur in the eemian interglacial and demonstrating that it extended to continental europe

correction for the siderite effect on rock eval parameters application to the sediments of lake barombi southwest cameroon abstract originally developed for use in the petroleum industry rock eval pyrolysis is a technique commonly applied to lake sediments to infer paleoenvironmental reconstructions the standard rock eval parameters provide information on the amount of total organic and inorganic carbon toc and minc respectively and are usually interpreted as proxies for the source aquatic or terrestrial of the primary production of organic matter hydrogen index vs oxygen index although this method usually provides valuable evidence the common presence of siderite in tropical lake sediments can alter the primary signal of the sedimentary organic matter som indeed the co2 and co released by the pyrolysis of siderite are integral to the calculation of the som related standard rock eval parameters in this study we analyze sediments from a core collected in the lake barombi southwest cameroon and describe the impact of siderite on standard rock eval parameters we propose a workflow that allows standard rock eval parameters to be corrected based on the analysis of thermograms the proposed corrections provide siderite effect free parameters accurately reflecting the changes in sedimentary organic matter composition

guidelines for rock eval analysis of recent marine sediments rock eval pyrolysis a widely used petroleum screening technique developed primarily for ancient sedimentary rocks and kerogens has now been increasingly applied to the characterization of recent lacustrine or marine sediments however as illustrated by previous results from various authors and by the analysis of recent sediments from various areas the thermally labile character of recent organic matter om the presence of poorly crystallized mineral e g carbonate and the eventual presence of salts nacl sulfate might perturb the detection of the pyrolysis effluent the aim here was to outline the problems generated by such perturbation and to demonstrate that specific operating conditions needed for proper analysis o frecent marine sediments a modified rock eval pyrolysis program starting at lower temperature 180 c with a heating rate of 30 c min is proposed as a standard mode for the analysis of recent om in order to avoid misleading interpretation of rock eval data and make possible the inter comparison of results whatever the rock eval device used

the nature and chronostratigraphy of quaternary pyroclastic accumulations from lake barombi mbo west cameroon abstract the k ar dating of a limburgitic flow indicates that the barombi mbo maar was active a million years ago the morphology of the maar and the unusual high k 2 o na 2 o ratio of the limburgite suggest either that this age is too old or that this flow is not the last activity of the maar twenty three meters of sediments were cored from the bottom core bm6 of the 110 m deep lake which currently fills the maar they are composed of clayey and sideritic laminae with interstratified ash layers in the lower half of the core these ashes composed of slightly vesiculated sideromelane with olivine and labradorite phenocrysts have been dated between 21 000 and 11 000 yr b p they show no alteration and correspond to aerial fallout of alkaline sodic basaltic affinity which is common in the area but are distinct from the mafic magmas which generated the maar the origin of the tilting and uplifting of a 1 5 m sedimentary column in the lower part of the core remains controversial holocene age pyroclastites are rare and consist of a mixture of granulitic xenocrysts and typically transitional tachylite similar to volcanics from the northeast manengouba magnetite microspherules occurring in holocene layers have no volcanic equivalent they could be related to biogenic or pedogenetic processes induced by more humid climatic conditions

the plant fossil record reflects just two great extinction events five great taxonomic extinctions the so called big five mass extinctions are widely recognized in life history at the end of the ordovician frasnian late devonian permian triassic and cretaceous all of them were originally identified in the marine fossil record and have been interpreted as the result of abrupt global environmental changes previous evidence has suggested that terrestrial biota were also subjected to ecological disruption during these events but it is unknown whether they suffered the same level of large scale taxonomic disruption as marine organisms here we show that the plant fossil record in fact only provides evidence of two mass taxonomic extinction events one through the carboniferous permian transition the other during middle late permian times this differs significantly from the mass extinctions recognized in the marine realm and suggests that vascular plants have a special capacity for surviving abrupt environmental changes

junggar turfan and alakol basins as late permian to early triassic extensional structures in a sinistral shear zone in the altaid orogenic collage central asia the junggar turfan and alakol basins in northwestern china and kazakhstan formed as late permian to early triassic extensional structures in a broad sinistral shear zone between large strike slip faults that separate two main domains of the altaid orogenic collage this extension was in response to an inferred large l000 km sinistral motion of the east european craton with respect to the angaran craton during this time deformation associated with the formation of the basins was taken up in part by counter clockwise rotations of crustal blocks with respect to the altaid orogenic collage and to the angaran craton this event is the only important phase of extension in a region otherwise dominated by compressional tectonics throughout the phanerozoic the basement rocks of these basins formed by altaid subduction accretion through the latter half of the palaeozoic and the region was subsequently thrown into compression again during the mesozoic cimmeride and cenozoic alpide evolution

early diagenesis of arsenic in sediments of the kalix river estuary northern sweden solid phase as fe mn s and al and pore water total as fe mn and s have been determined for two cores from the kalix river estuary at the same station the depositional flux of arsenic was measured sediment traps fe iii oxides persist in the anoxic zone of the sediment and act as a carrier for arsenic down to depths of 10 15 cm the release of arsenic into the pore water is controlled by the reduction dissolution of these oxides as a result internal cycling of arsenic i e upward diffusion in pore water re adsorption onto fe iii oxides in the oxidized surface layer and reburial occurs in the uppermost 10 15 cm at the base of the arsenic cycling zone solid phase arsenic maxima 160 170 g g 1 of probable diagenetic origin occur the quantity of arsenic diffusing back towards the oxidized surface layer 2 2 g cm 2 yr 1 as is close to 75 of the quantity of arsenic being deposited due to sedimentation 2 9 g cm 2 yr 1 as however a mass balance for the surface layer indicates that re adsorption of arsenic onto fe iii oxides may effectively prevent diffusion of dissolved arsenic back into the overlying water column it is concluded that the interpretation of sedimentary arsenic profiles may be severely complicated due to post depositional migration of arsenic

organic carbon sources and transformations in mangrove sediments a rock eval pyrolysis approach abstract a rock eval pyrolysis study was carried out on sedimentary cores and leaf and woody tissue of vascular plant species from the mangroves of french guiana these forests develop on moving mudbanks and have a lifetime limited to few decades before being eroded our main purpose was to complete the understanding of carbon cycling in this specific environment using a method that allows monitoring the depth evolution of sources and transformation of organic matter om within a tight depth span leaf and woody tissue showed clearly distinct rock eval parameters however these parameters strongly varied with om decomposition rapidly limiting their efficiency as mangrove plant tracers the decrease in values of tps2 pyrolysis temperature corresponding to the maximum release of hydrocarbons with depth clearly showed a line between a pedogenetic layer enriched in autochthonous om and marine sediments enriched in allochthonous om this allochthonous om originated from the particulate discharge of the amazon river which is partly deflected northwestwards by the current of the guianas within the soil layer decay processes induced a strong dehydrogenation and slight oxidation of om the two processes occurring simultaneously the deeper layers were characterized by a very strong increase in oico2 quantity of pyrolysed co2 relative to total organic carbon beneath both the young and the senescent forests this trend resulted rather from an increasing content of authigenic carbonate than from increasing concentration of oxidized allochthonous debris carbonate can form as a result of the more anoxic conditions prevailing in buried layers vs the upper suboxic ones beneath the senescent mangrove a greater increase in oico2 probably reflected greater carbonate precipitation resulting from the decomposition of higher amounts of om

turpanopitys taoshuyuanense gen et sp nov a novel woody branch discovered in early triassic deposits of the turpan basin northwest china and its palaeoecological and palaeoclimate implications abstract a novel well preserved woody branch turpanopitys taoshuyuanense gen et sp nov was collected in the early triassic terrestrial deposits in the turpan basin northwest china the permineralized wood is characterized by a heterogeneous pith endarch primary xylem and protophyllocladoxylon type secondary xylem the pith consists of parenchyma cells and supporting diaphragms formed by brick like sclerenchyma cells the quantitative growth ring analyses of t taoshuyuanense indicate that the species was evergreen the leaf longevity being comprised between 3 and 15 years t taoshuyuanense might indicate a warm humid climate with short dry periods in the turpan basin in the early triassic the protophyllocladoxylon type woods were widely distributed in different climate zone in both southern and northern hemispheres during the palaeozoic and early triassic the growth rings of the woods with protophyllocladoxylon type secondary xylem are good indicator for the palaeoclimate the new specimen indicates that a warm humid climate with irregularly distributed short dry periods in the early triassic turpan basin

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

palaeosol stratigraphy across the permian triassic boundary bogda mountains nw china implications for palaeoenvironmental transition through earth s largest mass extinction abstract upper permian and lower triassic palaeosols from northeastern tethyan localities exposed within the bogda mountains nw china provide a wealth of information regarding long term palaeoclimatic and palaeoenvironmental variations wuchiapingian palaeosols are characterized by intense redoximorphy accumulation of vascular plant matter accumulation of clay minerals and fe oxides slickensides and clastic dikes suggesting a soil moisture regime that ranged from perennially wet to distinctly seasonal in soil moisture budget changsinghian to early induan palaeosols include subsurface accumulations of clay and carbonate as well as surficial accumulations of organic matter indicative of sub humid to sub arid soil moisture and variable soil moisture regimes induan to olenekian palaeosols contain pedogenic caco 3 accumulations and gypsum pseudomorphs indicating a drier environment characterized by net soil moisture deficiency elemental composition of palaeosol matrix was used to estimate palaeoprecipitation through the chemical index of alteration minus potassium cia k proxy estimates from various wuchiapingian strata indicate relatively stable palaeoprecipitation during the late changsinghian and early induan palaeoprecipitation appears to have decreased from 1100 to 230 180 mm year over less than 100 m of vertical stratigraphic section in the induan and olenekian palaeoprecipitation appears much less stable than in wuchiapingian with values vacillating from 290 to 1014 mm year the transition to a relatively unstable precipitation state coincides generally with the permian triassic boundary and may reflect climatic disturbances associated with the end permian extinction event in addition to altered atmospheric circulation patterns resulting from regional tectonics moisture availability and expansion of the subtropical high pressure belt

lake sediments as natural seismographs earthquake related deformations seismites in central canadian lakes abstract central canada experiences numerous intraplate earthquakes but their recurrence and source areas remain obscure due to shortness of the instrumental and historic records unconsolidated fine grained sediments in lake basins are natural seismographs with the potential to record ancient earthquakes during the last 10 000 years since the retreat of the laurentide ice sheet many lake basins are cut into bedrock and are structurally controlled by the same precambrian basement structures shear zones terrane boundaries and other lineaments implicated as the source of ongoing mid plate earthquake activity a regional seismic sub bottom profiling of lakes gull muskoka joseph rousseau ontario wanapitei fairbanks vermilion nipissing georgian bay mazinaw simcoe timiskaming kipawa parry sound and lake of bays encompassing a total of more than 2000 kilometres of high resolution track line data supplemented by multibeam and sidescan sonar survey records show a consistent sub bottom stratigraphy of relatively thick lowermost lateglacial facies composed of interbedded semi transparent mass flow facies debrites slumps and rhythmically laminated silty clays mass flows together with cratered kettled lake floors and associated deformations reflect a dynamic ice contact glaciolacustrine environment exceptionally thick mass flow successions in lake timiskaming along the floor of the timiskaming graben within the seismically active western quebec seismic zone wqsz point to a higher frequency of earthquakes and slope failure during deglaciation and rapid glacio isostatic rebound though faulting continues into the postglacial lateglacial faulting diapiric deformation and slumping of coeval lateglacial sediments is observed in parry sound lake muskoka and lake joseph which are all located above prominent precambrian terrane boundaries lateglacial sediments are sharply overlain by relatively thin rhythmically laminated and often semi transparent postglacial silty clay laminations postglacial neotectonic activity is recorded by co seismic water escape structures faults slumps and debris flows in lake simcoe above a terrane boundary and especially within lakes timiskaming and kipawa recording ongoing deformation within the wqsz high resolution seismo stratigraphic data presented here support the model that ongoing mid plate earthquake activity is a consequence of brittle deformation of the upper crust of the north american plate such activity appears to have been greatest during deglaciation but continues today

sedimentation and palaeoenvironment in crater lake barombi mbo cameroon during the last 25 000 years lake barombi mbo is situated in a maar crater of the cameroon volcanic chain sediment cores were recovered with a livingstone corer this paper presents data on core bm6 23 5 m long from a water depth of 110 m the sediments are mainly organic matter rich clays 5 to 10 total organic carbon showing alternating brown and yellowish horizontal laminae on a cm scale the lower part of a couplet basal sublamina is rich in siliciclastic quartz mica grains sponge spicules and documents the deposition of flood detritus the upper unit upper sublamina is composed of grey to bluish clay which becomes green toward the top with frequently yellow layered concretions of siderite it corresponds to quiet conditions with settling of fine clayey particles from suspension the overall recurrence rate of these laminae is about 15 years this frequency is similar to present day large flood events in this intertropical zone from 14 000 to 20 000 yrs bp the sediment accumulation rate was quite low 15 30 g cm 2 10 3 yrs with less abundant precipitation pedogenic clay formed from mica family minerals from 12 000 yrs bp throughout the holocene the rate of accumulation increased 40 g cm 2 10 3 yrs and increasing precipitation favoured the pedogenic formation of kaolinites turbidity currents became less important to the overall sedimentation plankton production remained low documented by organic matter which is more of the exinite than the alginite type siderite concretions occur as early diagenetic products possibly related to alkalinity in anoxic waters at the sediment water interface which limited the formation of fe3 thin ash layers occur between 11 5 and 18 m depth in core bm6 bearing witness to several volcanic events during the late quaternary sediments are disturbed below 21 m with folded laminations and inverse ages these probably result from a slump glide of lower slope sediment but could also signal a possible gas event

late quaternary environmental changes and the alluvial record in humid tropical environments abstract ice core and ocean drilling records now confirm the evidence from lakes rivers and mires concerning temperature depression in the humid tropics during the lgm by at least 5 c on land and this accords with the recent ccm1 model output there is less agreement about fluctuation in precipitation amount intensity and seasonality during the late quaternary pollen records remain indeterminate because of the absence of sites in lowland rainforest locations and a widespread hiatus in sedimentation spanning the lgm alluvial sediments have often been ignored by specialists from other disciplines but they also provide a valuable source of palaeoenvironmental information that reflects catchment wide conditions current evidence shows that prolonged sedimentation took place in stage 3 at sites in s america and se asia and this was followed by incision for up to 9 ka spanning the lgm streams either produced little sediment or were characterised by braided channels and sometimes fan deposits until the transition towards an interglacial mode took place after 12 700 bp 14 c in many places this transition was marked by large floods incision and deposition of coarse sediment but as the holocene climates stabilised and fluctuations of runoff reduced in amplitude so meandering rivers developed floodplains with thick overbank silts and clays these changes have regional and intercontinental patterns not everywhere identical in bracketing dates but demonstrating major changes to the fluvial systems as a result of profound changes to the hydrology of forested tropics during the last 60 ka

timing and magnitude of tetrapod extinctions across the permo triassic boundary a review of the tetrapod amphibian and amniote record across the permo triassic boundary ptb indicates a global evolutionary turnover of tetrapods close to the ptb there is also a within guadalupian tetrapod extinction here called the dinocephalian extinction event probably of global extent the dinocephalian extinction event is a late wordian or early capitanian extinction based on biostratigraphic data and magnetostratigraphy the extinction precedes the illawara reversal so it is not synchronous with the end guadalupian marine extinction the russian ptb section documents two tetrapod extinction events one just before the dinocephalian extinction event and the other at the base of the lystrosaurus assemblage however generic diversity across the latter extinction remains essentially the same despite a total evolutionary turnover of tetrapod genera the chinese and south african sections document the stratigraphic overlap of dicynodon and lystrosaurus in the karoo basin the lowest occurrence of lystrosaurus is in a stratigraphic interval of reversed magnetic polarity which indicates it predates the marine defined ptb so as previously suggested by some workers the lowest occurrence of lystrosaurus cannot be used to identify the ptb in nonmarine strata correlation of the marine ptb section at meishan southern china to the karoo basin based primarily on magnetostratigraphy indicates that the main marine extinction preceded the ptb tetrapod extinction event the ecological severity of the ptb tetrapod extinction event has generally been overstated and the major change in tetrapod assemblages that took place across the ptb was the prolonged and complex replacement of therapsids by archosaurs that began before the end of the permian and was not complete until well into the triassic the tetrapod extinctions are not synchronous with the major marine extinctions at the end of the guadalupian and just before the end of the permian so the idea of catastrophic causes of synchronous ptb extinctions on land and sea should be reconsidered

septomedullopitys szei sp nov a new gymnospermous wood from lower wuchiapingian upper permian continental deposits of nw china and its implication for a weakly seasonal humid climate in mid latitude ne pangaea abstract septomedullopitys szei sp nov is described from the wuchiapingian wutonggou formation of tarlong valley southern bogda mountains xinjiang in northwestern china the stem has a heterogeneous pith ca 15 20 mm in diameter and containing numerous linear secretory ducts and parenchymatous bands primary xylem is endarch and the tracheids contain scalariform thickenings secondary xylem is of the protophyllocladoxylon type comparisons with contemporaneous gymnospermous woods containing either heterogeneous pith with ducts or protophyllocladoxylon type secondary xylem from the angara palaeocontinent indicate that the tarlong stem represents a new permian morphotaxon for the region the presence of coprolites borings and spindle shaped cavities within the stem suggests well developed animal plant fungi interactions the occurrence of numerous growth interruptions and absence of true growth rings within the stem suggest weak seasonality of annual precipitation the interruptions suggest a humid climate with short term nonperiodic droughts

early diagenetic influences on iron transformations in a freshwater lake sediment abstract iron transformations in a calcium carbonate rich fresh water sediment were studied by analyzing the relevant constituents of both interstitial water and solid matter analysis of interstitial water shows that the observed redox sequence no 3 nh 4 mno 2 mn ii feooh fe ii so 2 4 s ii is roughly in agreement with that predicted by the gibbs free energy for the corresponding reactions in contrast to marine sediments these redox transitions occur in the uppermost sediments i e at depths of 0 4 cm deeper in the sedimentary sequence the depth profile for dissolved iron exhibits a steady non linear increase up to 400 mol dm 3 in this anoxic zone according to thermodynamic predictions iron ii minerals such as iron sulfide siderite and vivianite should precipitate while fe iii oxides should be completely dissolved however microscopic analysis showed that fe iii oxides were present throughout the studied sediment furthermore scanning electron microscope energy dispersive spectroscopy analysis suggests the presence of iron sulfide could be verified but not that of siderite or vivianite these observations indicate kinetic control of iron transformations we have investigated the importance of kinetic control of iron distribution in anoxic sediments using a diagenetic model for dissolved iron ii a rough estimate of time scales for dissolution and precipitation rates was made by imposing limiting boundary conditions using the calculated rate constant we established that more than 1000 years would be required for the complete dissolution of fe iii oxides which is agreement with our observations and experimental data from the literature calculated precipitation rates of fe ii for a given mineral phase such as siderite yield a maximum value of 3 g feco3 g 1 dry sediment yr 1 such low rates would explain the absence of siderite and vivianite finally it can be inferred from the mn t fe t ratio in the sediments that this ratio depends on the redox conditions of the sediment water interface at the time of deposition thus this ratio can be used as paleo redox indicator in lacustrine sediments

global triassic tetrapod biostratigraphy and biochronology abstract eight temporally successive assemblage zones of tetrapod fossils provide the basis for dividing triassic time into eight land vertebrate faunachrons these land vertebrate faunachrons their type assemblage zones and their approximate correlation to the standard global chronostratigraphic scale are ascending order 1 lootsbergian lystrosaurus assemblage zone balfour katberg and burgersdorp formations karoo basin south africa late dorashamian induan 2 nonesian cynognathus assemblage zone burgersdorp formation karoo basin south africa olenikian 3 perovkan shansiodon assemblage zone donguz formation russian urals anisian 4 berdyankian mastodonsaurus assemblage zone bukobay formation russian urals ladinian early carnian 5 otischalkian paleorhinus assemblage zone chinle group chinle basin usa late early to early late carnian 6 adamanian rutiodon assemblage zone chinle group chinle basin usa latest carnian 7 revueltian pseudopalatus assemblage zone chinle group chinle basin usa norian 8 apachean redondasaurus assemblage zone chinle group chinle basin usa rhaetian the triassic land vertebrate faunachrons provide a framework for the correlation of triassic nonmarine deposits with a temporal resolution comparable to the seven triassic stage ages of the standard global chronostratigraphic scale

growth interruptions in silicified conifer woods from the upper cretaceous two medicine formation montana usa implications for palaeoclimate and dinosaur palaeoecology abstract taphonomic studies suggest that most dinosaur bone assemblages in the upper cretaceous campanian two medicine formation of montana originated from drought induced mass mortalities on the floodplain this hypothesis is tested further by studying intra annual growth patterns in silicified woods of cupressaceous taxodiaceous conifers found in association with dinosaur bone material at a palaeolatitude of 48 n true growth rings are completely absent but growth interruptions characterised by concentric variably persistent zones 1 8 latewood cells wide are common interruptions are irregularly spaced so that for example four interruptions may occur along a radius of only 25 cells in one specimen whilst in another specimen a radius more than 650 cells wide may completely lack interruptions irregular growth patterns like this occur in upper cretaceous woods across a broad latitudinal belt in the us western interior demonstrating that they resulted from regional climatic forcing rather than localised phenomena growth interruptions record the occurrence of short term aperiodic disturbances to tree growth under an equable megathermal climate that was otherwise favourable for continuous year round cambial activity the only probable cause of growth interruption formation were drought induced fluctuations in the water table and resultant water stress growth patterns suggest that sufficient water for uninhibited growth was continuously available for years at a time but when water stress did occur it did so repeatedly over a very few months comparison with present day east africa where trees show very similar growth patterns implies that the equable but erratically humid environment of the late cretaceous western interior was exactly the kind of setting where mass mortalities amongst megafauna might be expected like east africa this environment would have had sufficient carrying capacity to permit large herds of megafauna to develop under normal conditions but when repeated phases of droughts struck such populations would have been highly vulnerable

fragmentation of asia in the permian asia is a composite continent formed by the accretion of crustal blocks1 3 a likely sequence of events is that siberia collided with a kazakhstan block which together then collided with europe along the urals in permo triassic times2 this was followed by the sucessive accretion of various blocks of south and east asia to siberia culminating in the collision of india with asia during the cenozoic palaeomagnetic data have already demonstrated that the kolyma and sikhote alin blocks of eastern asia collided with the main continent along the late mesozoic fold belts of verkhoyansk and sikhote alin4 furthermore results from the malay peninsula5 and japan6 suggest that south east asia and japan were situated near the equator in permian times and were therefore separated from the asian continent we report here some palaeomagnetic results from the permian of the sino korean and yangtze blocks of china that show they were also situated near the equator were not in their present relationship to one another and were widely separated from siberia

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

stratigraphy biostratigraphy and c isotopes of the permian triassic non marine sequence at dalongkou and lucaogou xinjiang province china abstract measured lithostratigraphic sections of the classic permian triassic non marine transitional sequences covering the upper quanzijie wutonggou guodikeng and lower jiucaiyuan formations at dalongkou and lucaogou xinjiang province china are presented these measured sections form the framework and reference sections for a range of multi disciplinary studies of the p t transition in this large ancient lake basin including palynostratigraphy vertebrate biostratigraphy chemostratigraphy and magnetostratigraphy the 121 m thick wutonggou formation at dalongkou includes 12 sandstone units ranging in thickness from 0 5 to 10 5 m that represent cyclical coarse terrigenous input to the lake basin during the late permian the rhythmically bedded mudstone dominated guodikeng formation is 197 m and 209 m thick on the north and south limbs of the dalongkou anticline respectively and 129 m thick at lucaogou based on limited palynological data the permian triassic boundary was previously placed approximately 50 m below the top of this formation at dalongkou this boundary does not coincide with any mappable lithologic unit such as the basal sandstones of the overlying jiucaiyuan formation assigned to the early triassic the presence of multiple organic 13c isotope excursions mutant pollen and multiple algal and conchostracan blooms in this formation together with late permian palynomorphs suggests that the guodikeng formation records multiple climatic perturbation signals representing environmental stress during the late permian mass extinction interval the overlap between the vertebrates dicynodon and lystrosaurus in the upper part of this formation and the occurrence of late permian spores and the latest permian to earliest triassic megaspore otynisporites eotriassicus is consistent with a latest permian age for at least part of the guodikeng formation palynostratigrahic placement of the permian triassic boundary in the junggar basin remains problematic because key miospore taxa such as aratrisporites spp are not present palynomorphs from the guodikeng are assigned to two assemblages the youngest from the upper 100 m of the formation and the overlying jiucaiyuan formation contains both typical permian elements and distinctive taxa that elsewhere are known from the early triassic of canada greenland norway and russia the latter include spores assigned to pechorosporites disertus lundbladispora foveota naumovaspora striata decussatisporites mulstrigatus and leptolepidites jonkerii while the presence of devonian and carboniferous spores and early permian pollen demonstrate reworking is occurring in the guodikeng assemblages the sometimes common occurrence of scutasporites sp cf scutasporites unicus and other pollen suggests that the late permian elements are in place and that the upper assemblage derives from a genuine transitional flora of early triassic aspect in the junggar basin biostratigraphic data and magnetostratigraphic data indicate that the permian triassic boundary gssp level is in the middle to upper guodikeng formation and perhaps as high as the formational contact with the overlying jiucaiyuan formation

two episodes of 13c depletion in organic carbon in the latest permian evidence from the terrestrial sequences in northern xinjiang china new analyses reveal two intervals of distinctly lower 13c values in the terrestrial organic matter of permian triassic sequences in northern xinjiang china the younger negative 13corg spike can be correlated to the conspicuous and sharp 13c drops both in carbonate carbon and organic carbon near the permian triassic event boundary pteb in the marine section at meishan the geochemical correlation criteria are accompanied by a magnetic susceptibility pulse and higher abundances of distinctive chain like organic fossil remains of reduviasporonites the older negative 13corg spike originates within a latest permian regression significant changes in organic geochemical proxies are recorded in the equivalent interval of the marine section at meishan these include relatively higher concentrations of total organic carbon isorenieratane c14 c30 aryl isoprenoids and lower ratios of pristane phytane that together indicate the onset of anoxic euxinic and restricted environments within the photic zone the massive and widespread oxidation of buried organic matter that induced these euxinic conditions in the ocean would also result in increased concentrations of 13c depleted atmospheric co2 the latest permian environmental stress marked by the older negative 13corg episode can be correlated with the distinct changeover of ostracod assemblages and the occurrences of morphological abnormalities of pollen grains these observations imply that biogeochemical disturbance was manifested on the land at the end of the permian and that terrestrial organisms responded to it before the main extinction of the marine fauna