plant fossil distributions in some australian permian non marine sediments abstract plant remains occur in all post devonian lowland terrestrial depositional systems with distinctive assemblages characterizing discrete environments glossopterid gymnosperms dominate most australian permian coal bearing sediments herbaceous pteridophytes sphenophytes and lycophytes are best represented in lower deltaic lacustrine and paludal deposits non glossopterid gymnosperms mostly colonized drier floodplain and upland environments and are poorly represented in australian permian sequences fresh and brackish water algae are abundantly preserved in paludal and lacustrine facies in both alluvial and delta plain environments seasonal productivity and taphonomic factors undoubtedly influenced the composition of interseam compression impression floras but integration of information from these assemblages with that from permineralized peats in situ coalified plants and coal maceral and palynological analyses can assist in the interpretation of australian permian coal forming environments and the structure of plant communities

decoupling δ13c response to palaeoflora cycles and climatic variation in coal a case study from the late permian bowen basin queensland australia abstract the late permian coal measures of the bowen basin australia express both environmental and climatic changes that occurred prior to the permian triassic p t boundary in order to decouple the influence of environmental factors salinity ph base level and temperature from depositional and climatic factors atmospheric co2 in organic 13c a high resolution study was performed on 24 coal seams total 24 6 m in the late permian stratigraphy in the northern bowen basin the late permian stratigraphy of the bowen basin records a transition from deltaic and lacustrine conditions within the tinowan formation and black alley shale formation to fluvial deposition in the kaloola and bandanna formations intermittent volcanism is recorded by tuff layers during periods of peat accumulation variations of coal lithotypes were recorded and formed the basis of sampling for petrography and isotope analysis coal samples were etched to expose cellular anatomy and systematically identified to recognise palaeoflora assemblages when observed within seam 13c of the coal varied cyclically 13c enriched depleted enriched as a response to environmental changes expressed in palaeoflora communities the total range of 13c was 26 6 to 21 9 the overall trend of 13c progresses to increasing 13c enrichment corresponding with dull lithotypes rich in inertinite which indicate fluctuations in base level the 13c enrichment peaks at 22 5 within the kaloola member and shifting rapidly toward a depletion maximum 26 6 of 13c in the upper bandanna formation prior to the p t boundary these changes are expressed in palaeoflora communities where ecosystems shifted from dominant glossopteris flora to climax community flora including palaeosmunda cycadales and ginkgo suited to temperate early mesozoic climates the results of this study represent an insight into the effects of environmental variables on 13c uptake of plants the identification of flora within coal gives an insight into palaeowetland evolution and can be partnered with classic petrographical techniques for integrated analysis in coals both the geochemistry and the anatomical aspects of coal represent an important tool for future palaeowetland research

response of late carboniferous and early permian plant communities to climate change abstract late carboniferous and early permian strata record the transition from a cold interval in earth history characterized by the repeated periods of glaciation and deglaciation of the south

radiometric dating demonstrates that permian spore pollen zones of australia and south africa are diachronous abstract the well refined permian palynozonation of western and eastern australia is the current standard biostratigraphic scheme for the southern hemisphere but intra gondwanan floristic provincialism means that several stratigraphically useful palynomorph taxa are rare or absent elsewhere in gondwana radio isotopic ages for both australia and the main karoo basin of south africa demonstrate that key marker taxa appear diachronously in the two countries or they are absent in one of the countries the establishment of new plant taxa in the gondwanan permian realm was strongly tied to palaeolatitude with floral distributions primarily affected by temperature precipitation and seasonality this spatio temporal variation of floras hinders global biostratigraphic correlations both south africa and australia have excellent long ranging permo triassic terrestrial sedimentary successions and although vertebrate biostratigraphy has been the focus of much research endeavour in the south african karoo palynological studies have lagged accordingly a new south african palynozonation should be established that is based on the first appearances of key index taxa in the main karoo basin rather than elsewhere in gondwana in the interim the diachronous ranges of palynomorphs must be considered when correlating south african rocks to other global sections by means of the australian spore pollen zonation

controls on early permian shelf deglaciation in the karoo basin of south africa abstract the late carboniferous to early permian glacigene dwyka group has at its top three types of transitions from diamictite to postglacial mudrock in the southern karoo the type 1 transition sequence consists of clast poor carbonate rich diamictite having a sharp contact with the overlying mudrocks this diamicton accumulated slowly by rain out and sediment gravity flow processes during sedimentation the polar ice front was stabilised by a possible ice shelf collapse of the ice shelf caused rapid ice margin retreat the type 2 transition sequence consists of clast poor diamictite with sandstone bodies overlain by mudrock with ice rafted debris or thin interbedded debris flow diamictites deposition of the diamictite facies occurred during oscillations of a subpolar ice front with short stable periods of surface melting of the ice resulting in the formation of small subaqueous outwash fans the type 3 transition sequence consists of bouldery diamictite interbedded with massive or sandstone bearing diamictite overlain by mudrock with ice rafted debris or thin interbedded debris flow diamictites the sequence represents highly unstable ice front conditions and fluctuating sea levels with periods of rapid deposition probably by collapsing ice streams climatic conditions may have alternated between polar and subpolar the type 1 transition sequence is predominant in the western part and the type 3 sequence in the eastern part of the karoo basin long term controls on deglaciation was climatic warming as gondwana drifted over the pole as well as changes in land sea configuration superimposed on these were local controls such as relative sea level changes presence of deformable substrate and meltwater production

permian phytogeographic patterns and climate data model comparisons abstract the most recent global icehouse hothouse climate transition in earth history began during the permian warmer polar conditions relative to today then persisted through the mesozoic and into the cenozoic we focus here on two permian stages the sakmarian 285 280 ma and the wordian 267 264 ma also known as the kazanian integrating floral with lithological data to determine their climates globally these stages postdate the permo carboniferous glaciation but retain a moderately steep equator to pole gradient judging by the level of floral and faunal differentiation floral data provide a particularly useful means of interpreting terrestrial paleoclimates often revealing information about climate gradations between dry and wet end member lithological indicators such as evaporites and coals we applied multivariate statistical analyses to the permian floral data to calibrate the nature of floral and geographical transitions as an aid to climate interpretation we then classified sakma

hypautochthonous allochthonous coal deposition in the permian south african witbank basin no 2 seam a combined approach using sedimentology coal petrology and palaeontology abstract a suite of techniques including coal petrology micropalynology mesofossil analysis and macroscopic appearance has been used to examine the early permian south african witbank basin no 2 seam from a sample locality near ogies this coal appears to be similar in its palynological and petrographic composition to other coals of this interval from this basin however its accumulation appears to have been largely hypautochthonous or allochthonous evidenced by erosive contacts small scale cross laminations and fine lenticular bodies being recognised within the coal seam profile this ex situ deposition probably in part relates to frequent wildfire activity which may have promoted subsequent run off and erosion and led to the numerous mineral rich horizons observed in the sample seam profile in addition to the sedimentological characters described above the petrology of the seam and its mesofossils most particularly megaspores from a lycopsid parent vegetation indicate saturated peat forming conditions however examination of charred mesofossil fragments indicates periods of low humidity and even drying of the peat itself rendering it liable to combustion these contradictory characters may indicate seasonality and suggest a coldness of the climate at least for part of the year that could account for the retardation of peat decay during these drier intervals these characters can be reconciled with deposition during an interglacial phase as the dwyka glaciation terminates as has previously been proposed for the witbank basin no 2 seam

pennsylvanian and cisuralian palynofloras from the los sauces area la rioja province argentina chronological and paleoecological significance abstract three outcrops of the libertad and sauces formations from the los sauces area la rioja province western argentina yielded the nine palynoassemblages studied here two assemblage zones are defined on the basis of the stratigraphic distribution and ranges of seventy five species of palynomorphs 42 species of spores 32 pollen taxa and one fungus only thirteen species are common to both assemblages and ten species are first records for the paganzo basin assemblage 1 from the libertad formation is dominated by trilete spores of cristatisporites lycophyte and punctatisporites pteridophyte monosaccate pollen coniferales cordaitales is frequently present pteridosperms mostly represented by cyclogranisporites are especially abundant in one level together with scarce striate bisaccate pollen grains assemblage 2 of the sauces formation is dominated by trilete spores related to the pteridophyta e g horriditriletes converrucosisporites granulatisporites and sphenophyta monosaccate cordaitales coniferales and taeniate and non taeniate bisaccate pollen grains pteridospermales coniferales are equally subordinated monosulcate pollen cycadophyta and fungi portalites gondwanensis are rare assemblage 1 is mainly moscovian assemblage 2 asselian sakmarian this interpretation is based on correlation of assemblage 1 to the dmb mid pennsylvanian and assemblage 2 to the fs early cisuralian biozones of the paganzo basin argentina the taxonomic composition of the ahrensisporites cristatus crucisaccites monoletus mid late pennsylvanian and the protohaploxypinus goraiensis subzone asselian sakmarian of the vittatina costabilis early cisuralian biozones of the parana basin brazil support this correlation the continental freshwater depositional setting of this part of the paganzo basin is supported by the dominance of terrestrial palynomorphs and phytoclasts the presence of coal and carbonaceous shales and the occurrence of plant megafossils and plant debris in the sediments the floristic changes between assemblages 1 and 2 are consistent with the interpretation of climatic amelioration associated with paleogeographic changes in gondwana occurring during the pennsylvanian and cisuralian

the late permian climate what can be inferred from climate modelling concerning pangea scenarios and hercynian range altitude abstract a major unsolved geodynamic problem is the permian pangea plate configuration at the end of paleozoic era around 255 ma while consensual geology indicates a plate arrangement close to that of the jurassic prior to the atlantic opening pangea a paleomagnetic data indicates a nearly 3000 km more eastward position of gondwana with respect to laurussia leading to major plate and relieves reorganisation during permo triassic times pangea b using an atmospheric general circulation model agcm we simulate the climatic response to both configurations we also test the fundamental role of paleo elevations through sensitivity experiments each simulated climate is then compared with the aim of constraining the best fit to a particular paleogeographic scenario main trends of simulated late permian climate in agreement with paleoclimatic indicators are 1 a warm temperate climate accompanied by a monsoon circulation over the eastern side of gondwana 2 a cold temperate climate marked by strong annual thermal amplitude at high latitudes in gondwana and in siberia 3 an arid belt in the subtropics over the western side of gondwana and laurussia and 4 strong climatic differences over both hemispheres respectively main variance is found over laurussia with a simulated tropical climate while an arid climate is suggested by paleodata simulating different paleo elevations of the appalachian and the variscan fold belts can solve this discrepancy the best model data fit is reached for a mean altitude of 4500 m in the appalachians and appears to be dependent of pangea configuration with a southern europe variscan range of some 3000 m in a pangea a configuration or only 2000 m in for pangea b taking into account the geodynamic context we argue that pangea b appears to be the more probable configuration

eolian permian deposits in west and northwest argentina abstract the sedimentary and stratigraphic characteristics of eolian permian deposits exposed in mendoza la rioja and san juan provinces west and northwest argentina are described in this paper the eolianites are fine and medium sandstones with large scale cross bedding multiple parallel truncation planes and some asymmetrical ripples three genetic types of deposits have been identified dune facies eolian sand sheet facies and mixed fluvial eolian facies fine and medium sandstones with large scale cross bedding and multiple parallel truncation planes are here interpreted as dune deposits mainly crescentic dunes and unstratified or flat bedded sandstones as eolian sand sheet deposits mixed fluvial and eolian sequences composed of sandstones mudstones and some matrix supported conglomerates represent a transitional facies between those formed in eolian and fluvial environments this considerable deposition of eolian sediments was probably brought about by the existence of an extensive medium to low latitude continent and the withdrawal of marine environments the environments with highest aridity occurred towards the south and west of the region the eolian circulation pattern was controlled by a long ensialic volcanic arc emerging towards the west of the basin

the late palaeozoic to early mesozoic evolution of southern south america a plate tectonic interpretation the limits of 3 distinct upper palaeozoic to lower mesozoic tectono stratigraphic zones of the ancestral pacific margin of gondwana in southern south america are documented these are a fore arc region consisting in part of oceanic components a magmatic arc that is coincident with carboniferous to triassic continental sedimentation and a back arc region comprising the upper palaeozoic epicratonic sequences of the samfrau geosyncline these zones traceable 2300 km from 29 56 s cape horn document the semi continuous subduction of the ancestral pacific floor from the middle devonian to the triassic between 29 s and 37 s the palaeo subduction zone was roughly coincident with the present pacific coast line between 37 s and cape horn the subduction zone migrated progressively westward as an alaskan style accretionary prism grew to a width of 250 km while in the northern sector jurassic are intrusions are coincident with the upper palaeozoic are intrusions in the s they intruded the upper palaeozoic to lower mesozoic accretionary prism 200 km w of their palaeozoic equivalents no post middle palaeozoic sutures have been identified in southern south america hence there is no evidence of late palaeozoic mesozoic or cenozoic accretion of discrete microplates

patterns of insect mediated damage in a permian glossopteris flora from patagonia argentina abstract a total of 2523 fossil plant specimens from the la golondrina formation permian santa cruz province argentina were examined in order to assess the diversity frequency and representation of insect damage although no evidence of arthropod bodies have been found in the unit their past presence is recorded through various types of plant insect interactions involving oviposition external feeding piercing and sucking galling and potential mine structures results show that at least 186 specimens all of them plant leaves suffered from some type of insect herbivory among the many damage types identified some of them recognized for the first time in gondwanan floras oviposition and external feeding occurred most frequently followed by piercing and sucking and galling glossopterid foliage was the preferred target over the rest of plant groups and it was common to find more than one type of damage on the same leaf suggesting these were exploited for multiple purposes by the insects compared to the northern hemisphere permian floras the la golondrina formation herbivory levels were low and similar to those of other glossopteris floras from gondwana

permian phytogeography in gondwana abstract phytogeographic patterns based on multivariate techniques multidimensional scaling are proposed for the permian vegetation of gondwana this approach requires a data set with broad geographic coverage based on generic composition and with good time control in general strong phytogeographic differentiation can be observed throughout the permian in order to identify short term phytogeographic patterns the permian period was informally divided into five time slices in the permian stage i earliest permian the vegetation was strongly influenced by glacial conditions a very impoverished vegetation is seen except in patagonia and parts of south america four units were identified patagonia nothosouthamerica australia and indo africa by far patagonia was the most diverse and had the most favourable climatic conditions perhaps as a result of palaeogeographic separation from western gondwana nothosouthamerica which included plant assemblages from nw argentina and brazil perhaps as two subunits is a mid latitude area with glacial influence in the brazilian sector indo africa had a much lower diversity occupying high latitudes whereas australia had the lowest diversity of all the vegetational regions in stage i the early permian stage ii shows a more diversified and expanded plant cover vegetation of eastern and western gondwana was differentiated patagonia and south america including a brazilian and nw argentinean unit had the richest plant assemblages whereas africa indo australia and antarctica as separate units are less diverse probably due to late glacial influence by the late early permian stage iii gondwana shows much more ameliorated climatic conditions basically due to drifting into more temperate latitudes as well as increased moisture resulting in expansion of peat forming areas this is immediately reflected in the vegetation as shown by diversified plant assemblages even in antarctica nonetheless a differentiation is again observed between eastern gondwana patagonian and south american units and the western sector indo australian and antarctic units whereas africa would probably represent an ecotone beginning in the late permian stage iv there was a decrease in the number of plant assemblages and diversity indicating a deterioration in climate resulting from generally drier conditions latitudinal differentiation can be observed with antarctica as a polar unit afro australia at high latitudes whereas the south american indian and patagonian units are located in middle latitudes finally in permian stage v latest permian a south american unit can be differentiated clearly from the rest africa and indo australia antarctica is interpreted again as a discrete unit in the stage v time slice eastern gondwana returns to more humid climatic conditions allowing the formation of extended peat swamps whereas the western sector is affected by seasonal and strong droughtness this kind of phytogeographic approach has proven useful for detecting some palaeogeographic problems such as those involving the patagonian subcontinent in this regard palaeogeographic reconstructions and palaeoclimatic models should be tested against these phytogeographic patterns

climate changes and cyclic sedimentation in the mid late permian kennedy group carnarvon basin western australia climate has an important direct and indirect influence of sedimentation and especially on the development of cyclic sedimentation climate influences both accommodation and supply the major controls on the architecture of sedimentary sequences the permian paleoclimate is the subject of increasing controversy giving rise to numerous differing models developed and an expanding database of fossil evidence for climatic conditions western australian basins in particular the carnarvon basin are unique among nearby gondwanan basins in that they do not have extensive coal measures within their permian successions the kennedy group the uppermost unit in the onshore carnarvon basin permian succession has a detrital composition indicative of arid weathering conditions within the kennedy group even lagoonal and very nearshore sediments are devoid of plant debris or indications of the nearby presence of extensive flora presumed surfaces of subaerial exposure do not show paleosol development or root traces there has been little development of clay and chemical grain degradation is almost entirely related to diagenetic cementation and dissolution phases rather than transport and source weathering nearby basins at similar latitudes in india and east australia contain coal measures consistent with the humid climates that are predicted for this latitude it is suggested therefore that the inferred aridity in the climate of the carnarvon basin and other western australian basins is due to local climatic effects probably related to an interruption in atmospheric circulation caused by tectonic rifting and uplift to the west cyclicity in the kennedy group indicates regular late permian milankovitch scale eustatic sea level change and may signify the presence of some ice at the poles the development of cycles may have been enhanced by shifting climate belts controlled by milankovitch cyclicity

the burning of gondwana permian fires on the southern continent a palaeobotanical approach abstract fossil charcoal has widely been accepted as a direct indicator for the occurrence of palaeo wildfires in upper palaeozoic sediments of euramerica and cathaysia records of these remains are relatively common and regionally and stratigraphically more or less homogeneously distributed in terrestrial sequences on the other hand just a few records have been published for the permian of gondwana and only recently has it been demonstrated that macroscopic charcoals are also common here most permian macroscopic charcoal from gondwana is gymnospermous and has been reported from coal bearing strata macroscopic charcoal occurrences are spread out in different sequences and also in distinct stratigraphic intervals in the permian e g parana basin sakmarian artinskian of brazil karoo basin artinskian of south africa damodar basin lopingian of india and dead sea area changhsingian of jordan they range from peri glacial post glacial to warm temperate climatic systems throughout the permian macro and micro charcoal occurrences are compared to inertinite incidences to support the pyrogenic origin for these coal macerals and to provide an up to date overview on the known evidences of permian wildfires on gondwana in space and time

permo carboniferous climate early pennsylvanian to late permian climate development of central europe in a regional and global context a well justified stratigraphical correlation of continental successions and new palaeogeographic reconstruction of pangaea reveal new insights into the northern pangaean climate development influenced by palaeogeography palaeotopography glacio eustatic sealevel changes and ocean currents the overall permo carboniferous aridization trend was interrupted by five wet phases these are linked to the gondwana icecap the aridization and weakening of wet phases over time were not only caused by the drift of northern pangaea to the arid climatic belt but also by the successive closure of the rheic ocean which caused the expansion of arid semi arid environments in the lower middle permian the end of the gondwana glaciation rearranged ocean circulation leading to a cold coast parallel ocean current west of northern pangaea blocking moisture coming with westerly winds the maximum of aridity was reached during the roadian wordian the trans pangaean mountain belt was non existent its single diachronous parts never exceeded an average elevation of 2000 m the maximum elevation shifted during time from east to west the hercynian orogen never acted as an orographic east west barrier and the inter tropical convergence zone was widely displaced causing four seasons dry summer winter wet spring autumn at the equator and a strong monsoon system the climate history of the european realm during the late carboniferous pennsylvanian and permian is stored in many solitary basins fig 1 within the hercynian orogen and the foreland basin the story of westphalian climate is well known because of the numerous investigations of the coal bearing variscan foredeep the younger westphalian is characterized by a slight aridization abbink van kronijnenburgvan cittert 2003 oplustil 2004 which was accompanied by an increase of seasonality nevertheless the environment was strongly influenced by the ocean and epi continental seas with multiple transgression events the last extensive marine ingression was the aegir mansfield band westphalian b c the post westphalian climate development is more differentiated and

diversity of the woody vegetation of gondwanan southern africa abstract the flora of gondwanan southern africa is represented in the rock record by micro fossils macro fossils and petrified woods all these types of fossils are seldom preserved together in any one particular facies because of taphonomic and preservational biases in order to obtain as accurate a picture as possible of the woody vegetation both the fossil woods and other macroplant fossils such as leaf impressions fructifications and cuticle of woody plants have been correlated this was done for each formation in the karoo supergroup in order to illustrate the changes in diversity of woody vegetation over time sediments of the karoo supergroup represent the terrestrial fossil record of the period upper carboniferous to the lower cretaceous when africa finally separated from south america in the upper carboniferous to lower permian dwyka formation there are at least five described genera of woods from south africa and namibia early to middle permian woods ecca group are a little more diverse with six genera representing the glossopterids cordaitaleans and possibly other seed fern groups late permian to early triassic beaufort group woods show very little change in diversity in spite of the major floral and biotic turnover evident from the rest of the fossil record although the late triassic molteno formation macro flora has been shown to be an example of explosive diversification the generally poorly preserved woods do not reflect this lower jurassic fossils clarens formation are also poorly preserved but have araucarian characteristics early cretaceous woods represent the araucariaceae cheirolepidiaceae and podocarpaceae with a number of species the diversity of the woods has not changed as much as the rest of the floral components in southern africa from the late carboniferous to the early cretaceous possible reasons for this apparent stasis are the conservative nature of wood functional restrictions limitations of suitable conditions for petrifications and the fact that very little research has been done on southern african woods

the effect of global warming and global cooling on the distribution of the latest permian climate zones abstract the end permian biotic crisis is commonly associated with rapid and severe climatic changes these climatic changes are commonly suggested to have originated from solid earth carbon degassing leading to global warming but aerosol and ash induced cooling induced by lava degassing has been suggested as well the application of an earth system model of intermediate complexity has enabled a visualisation of the major climatic shifts on the supercontinent pangaea caused by rapid temperature changes due to changed radiative properties from greenhouse gases the reconstructed reference climate was validated by latest permian climate indicative sediments to investigate the possible climatic shifts from a set of 22 reconstructions which varied with temperature a minimum global annual mean temperature of 18 2 c for the late permian climate prior to the climatic perturbation event was determined starting from this pre event setup global warming and global cooling scenarios were simulated the response of the end permian climate system to temperature increase and decrease show marked differences while global cooling is followed by major climatic changes in the high latitudes and replacement of boreal biomes by tundra and polar frost the changes during global warming are less pronounced with only locally increasing aridity compensated by humidisation in other regions the different behaviour of the climatic belts under warm and cold conditions is accompanied by different climate sensitivities caused by different strength of the snow cover albedo feedback thus changes in the energy balance of the latest permian surface troposphere system have a 30 higher perturbation potential during cold climate conditions than during warmhouse conditions therefore substantial global cooling resulting in coldhouse climate conditions and an annual global mean temperature below 18 c is more efficient in perturbing the earth palaeoclimate during the end permian warmhouse the results suggest that global cooling mechanisms as injection of sulphur aerosols and ash particles from the siberian traps large igneous province into the late permian palaeoatmosphere have a higher climate perturbation potential than a warming due to carbon greenhouse gases with a similar magnitude of radiative forcing

the sedimentology and accretionary styles of an ancient gravel bed stream the budleigh salterton pebble beds lower triassic southwest england abstract three accretionary styles are present in the fluvial conglomerates and pebbly sandstones of the lower triassic budleigh salterton pebble beds bspb of east devon the lower portions of this 20 30 m sequence are dominated by extensive 50 m sheets or narrow lenses of planar cross bedded conglomerate sets 1 3 m thick these abruptly pass both downstream and laterally into horizontally bedded conglomerates cross bedded sandstones and muddy sandstones this accretionary style reflects deposition from linguoid shaped macroforms whose distal margins were bounded by slipfaces they accreted at anabranch confluences and as bank attached bars in relatively confined and channelised gravel bed streams lateral facies changes represent macroform evolution resulting from changing discharges or abandonment of a channel reach followed by accretion of a new macroform the upper portions of the bspb mainly comprise couplets of horizontally bedded conglomerate overlain by large scale trough cross bedded sandstone the conglomerate shows local channel macroform relief and lateral and downstream transitions into sets of gently dipping conglomerate this style of accretion represents deposition in less confined and less channelised fluvial systems by relatively low relief gravel macroforms and large sand dunes the third style recognised in the bspb is much more localised it consists of wedge like sets of large scale trough cross bedded conglomerate the sets are formed by erosion and subsequent fill of scours cut into a thick sandy substrate techniques of lateral profile analysis and hierarchical ordering of bounding surfaces can usefully be applied to some parts of the bspb this is important as the approach was originally developed for the deposits of sand bed streams however this approach is more difficult to apply to fluvial conglomerates because of the cryptic nature of some gravel stratification the appearance and character of some hierarchies of bounding surfaces may differ from their equivalents in fluvial sandstones

early permian asselian vegetation from a seasonally dry coast in western equatorial pangea paleoecology and evolutionary significance abstract the pennsylvanian permian transition has been inferred to be a time of significant glaciation in the southern hemisphere the effects of which were manifested throughout the world in the equatorial regions of pangea the response of terrestrial ecosystems was highly variable geographically reflecting the interactions of polar ice and geographic patterns on atmospheric circulation in general however there was a drying trend throughout most of the western and central equatorial belt in western pangea the climate proved to be considerably more seasonally dry and with much lower mean annual rainfall than in areas in the more central and easterly portions of the supercontinent here we describe lower permian upper asselian fossil plant assemblages from the community pit formation in prehistoric trackways national monument near las cruces south central new mexico u s a the fossils occur in sediments within a 140 m wide channel that was incised into indurated marine carbonates the channel filling can be divided into three phases a basal channel limestone conglomerate facies contains allochthonous trunks of walchian conifers a middle channel fill is composed of micritic limestone beds containing a brackish to marine fauna with carbon oxygen and strontium isotopic composition that provide independent support for salinity inferences the middle limestone also contains a par autochthonous adpressed megaflora co dominated by voltzian conifers and the callipterid lodevia oxydata the upper portions of the channel are filled with muddy gypsiferous limestone that lacks plant fossils this is the geologically oldest occurrence of voltzian conifers it also is the westernmost occurrence of l oxydata a rare callipterid known only from the pennsylvanian permian transition in poland the appalachian basin and new mexico the presence of in situ fine roots within these channel fill limestone beds and the taphonomic constraints on the incorporation of aerial plant remains into a lime mudstone indicate that the channel sediments were periodically colonized by plants which suggests that these species were tolerant of salinity making these plants one of if not the earliest unambiguous mangroves

iceberg rafting and scouring in the early permian shoalhaven group of new south wales australia evidence of heinrich like events abstract this paper describes multiple layers of ice rafted debris and an ice scour structure in early permian marine strata within the shoalhaven group of the sydney basin new south wales australia strata were deposited on a high latitude glacially influenced continental margin during the final stages of late palaeozoic glaciation between 277 and 260 ma poorly sorted ice rafted debris forming layers up to 1 25 m thick is common within inner to outer shelf and continental slope facies of the shoalhaven group more than 120 layers can be identified these are argued to record the enhanced delivery of debris by icebergs drifting north from marine based antarctic ice margins deformation structures in associated sediments are interpreted as iceberg scours and ice keel turbates associated glendonites record early diagenesis of organic rich sediment and bottom water temperatures close to freezing a speculative hypothesis relates layers of ice rafted debris within the shoalhaven group to multiple episodes of accelerated calving at the margins of a marine based early permian ice sheet in east antarctica these events may be analogous to late pleistocene heinrich events when huge armadas of icebergs were released from the marine based laurentide ice sheet and triggered abrupt changes in ocean circulation and climate similar forcing may have characterized the early permian ice ocean system regardless of the climatic significance of ice rafted layers this is the first time such facies have been documented in the pre pleistocene literature to date few ice scour structures and no ice keel turbates have been reported

pangaean climates megamonsoons of the megacontinent the climate for a highly idealized geographic representation of the megacontinent of pangaea corresponding to the period 250 200 m y ago is explored using a low resolution atmospheric general circulation model that is coupled to a static mixed layer ocean of constant depth with a provision for sea ice formation and decay soil moisture is included as a predicted variable on the continent because there are large uncertainties about key factors that might influence the pangaean climate sensitivity experiments are used to examine the climate for two different mean elevations 0 and 1000 m two different snowcover prescriptions and two different levels of implied greenhouse heating and solar luminosity modern co2 concentration and modern solar luminosity fivefold increase in modern co2 concentration and a 1 decrease in modern solar luminosity in all of the experiments the large bipolar land masses of laurasia and gondwanaland joined near the equator in the west and separated by the tethys sea in the east exhibit extreme continentality with hot summers cold winters and large scale summer and winter monsoon circulations year round or seasonal aridity is simulated for all but the eastern coastal regions the tropical western coast and the regions poleward of 40 latitude the simulated climate of the idealized pangaean continent has many features that correspond qualitatively with geologic evidence for tropical warmth and aridity in the late permian and triassic however the model results serve mainly to indicate the importance of various climate forming factors geography topography heating detailed comparisons will require new experiments with better models and more accurate geologic boundary conditions

assemblages with titanite catiosio4 ca mg fe olivine and pyroxenes fe mg ti oxides and quartz part ii application in the system cao mgo feo fe2o3 tio2 sio2 equilibria among titanite pyroxene s olivine spinel phase ilmenite and quartz constrain f o2 t a sio2 a tio2 a fe and the compositional variables tife2 fe 23 c a mg fe 1 and consequently mg fe 1 among the silicate and oxide phases these equilibria can provide the framework for a better understanding of relevant titanite bearing natural assemblages in addition such equilibria can constrain the variables that operate during crystallization of igneous and metamorphic rocks titanite bearing assemblages with pyroxene s fe mg ti ilmenite and spinel olivine and quartz are rare in metamorphic rocks but are common in igneous rocks where they are more commonly reported in plutonic than in volcanic rocks probably because at high temperatures titanite cannot coexist with the relative common in volcanic rocks sub assemblage augite orthopyroxene olivine spinel phase ilmenite moreover decreasing pressure and temperature conditions appear to favor titanite thus it is not surprising that titanite is commonly observed in slowly cooled rocks albeit most typically in association with amphibole we argue that the titanite amphibole association is favored by high a h2o and because a h2o typically increases during crystallization of a pluton titanite amphibole and consequently titanite is more common in plutonic than in volcanic rocks we have used a modified version of the program quilf that includes our thermodynamic data for titanite and appropriate titanite bearing assemblages to estimate the equilibrium crystallization conditions of samples from 1 a tonalite from the myoken zan granitic complex in japan 2 the sandwich horizon in the skaergaard intrusion in greenland 3 rhyodacites dacites and andesites from the sajama porquesa and parinacota volcanoes in the andes 4 the fish canyon tuff in colorado and 5 a quartz rich calc silicate gneiss adjacent to the horse creek anorthosite complex in wyoming the calculations suggest that 1 these titanite bearing assemblages crystallized at values of f o2 that ranged from slightly below fmq to more than 3 log f o2 units above fmq at 500 800 c and 2 the stability of titanite is controlled by t f o2 a sio2 and the compositions of the coexisting oxides and silicates

contribution of late permian palaeogeography in maintaining a temperate climate in gondwana numerical simulations based on general circulation and energy balance models consistently indicate that the high latitudes of gondwana experienced seasonal extremes in climate during the late permian period1 3 but palaeogeographic maps based on the distribution of climate sensitive rocks4 palynological and palaeobotanical data5 6 and dicynodont fossil records7 all imply a temperate climate the reason for this discrepancy has not been clear recently it has emerged from studies of upper permian fluviolacustrine deposits throughout southern africa that the geography was dominated by a series of giant lakes perhaps interconnected within major fluvial frameworks8 here i review these data and their implications for a temperate climate i suggest that the discrepancy between the climate modelling results which indicate seasonal temperature extremes and the increasing body of geological information documenting a temperate climate may be explained by the fact that the palaeogeography used in the models does not take into account the existence of these lakes and rivers which would have had a major influence on the regional climate the results demonstrate the importance of incorporating accurate palaeogeographies into numerical modelling studies when attempting to reconstruct past climates

study of the west gondwana floras during the late paleozoic a paleogeographic approach in the parana basin brazil abstract the late paleozoic in west gondwana was a period of significant climatic changes ranging from a glacial climate in the late carboniferous to a semi arid climate in the late permian the floristic province of gondwana in the parana basin was directly affected by such changes and underwent a transformation regarding composition and geographic distribution thus the climatic phases were divided into three intervals phase a containing interglacially developed flora phase b containing floras of immediate post glacial temperate climates and phase c identified with floras related to the decline of dryness regarding their geographical distribution the floras were concentrated in the far northern and far southern portions of the basin during the glacial interval and with a gradual increase in temperature went on to occupy the entire basin finally we can see that the floras located in the argentinean portion of west gondwana are older and have greater species diversity than those present in the parana basin and africa during phase a in phase b there is a decline of argentinean flora species a large increase in the parana basin floras and an average increase in african floras in the final stage the floristic province no longer exists in argentina the flora of the parana basin also suffers a decrease of specimens and the african flora undergoes its moment of greatest development such diversity change also reflects a west to east migration throughout the late carboniferous

resolving the age of madumabisa fossil vertebrates palynological evidence from the mid zambezi basin of zambia age estimates for permian rocks in the mid zambezi basin of zambia have thus far yielded ambiguous results previously studied palynoassemblages from the madumabisa formation resemble spore pollen suites from both the cistecephalus zone of north luangwa lopingian and the palynological assemblage sub zone iv h of zimbabwe proposed as guadalupian in order to improve age estimates and refine the biostratigraphy of the madumabisa formation this formation together with the underlying gwembe formation were sampled for palynomorphs assemblages from the gwembe formation are dominated by trilete spores with less common striate and non striate bisaccate pollen whereas the overlying madumabisa formation palaeoflora is composed predominantly of striate bisaccates ferns pteridosperms lycopods sphenophytes glossopterids and conifers are represented in the palynofloras the upper gwembe formation palynoassemblage can be correlated with the didecitriletes ericianus zone of backhouse 1991 the guttulapollenites hannonicus protohaploxypinus rugatus zone zone vi of aitken 1998 assemblage zone iii of the mid zambezi basin zimbabwe and biozone kk 3 in the kalahari karoo basin botswana suggesting a guadalupian wordian capitanian age the upper madumabisa formation palynoassemblage can be placed in the upper dulhuntyispora parvithola zone of backhouse 1991 app5 of price 1997 dated as wuchiapingian lopingian and correlates with assemblage 2 of the moatize minjova basin mozambique and the mckinnon member palynofloras of east antarctica it also resembles daptocephalus formerly dicynodon assemblage zone palynofloras of the lower and middle balfour formation in the karoo basin south africa and is suggested to be lopingian wuchiapingian changhsingian in age although these palynological assemblages place lower and upper age constraints on madumabisa formation vertebrate fossils uncertainty remains as to the exact correlation between the madumabisa vertebrate assemblages and the assemblage zones of the main karoo basin