magnetostratigraphic constraints on the age of the lower beaufort group western karoo basin south africa and a critical analysis of existing u pb geochronological data we studied three partially overlapping sections with a composite thickness of 600 m in the upper permian fluvial siltstones and fine grained sandstones of the abrahamskraal formation the basal unit of the beaufort group in the karoo basin of western cape province south africa paleomagnetic analysis reveals three components of natural remanent magnetization nrm heating to 180 c removes a remanent magnetization parallel to the present day field which is interpreted as a viscous overprint an intermediate unblocking temperature component is removed by heating to 450 c this direction is always of normal polarity and is identical to a regional overprint imparted during the early jurassic emplacement of the karoo large igneous province a high temperature component isolated above 450 c is of dual polarity and is interpreted as primary on the basis of a positive reversals test the virtual geomagnetic pole position for the abrahamskraal formation computed from the average high temperature characteristic remanent magnetization direction is in agreement with the late permian directions for stable gondwana and with previous results from the lowermost abrahamskraal formation and waterford formation at the ouberg pass section the predominantly normal polarity of this magnetization is in agreement with either a middle late lopingian age ca 254 256 ma or a late guadalupian age ca 262 ma according to the global geomagnetic polarity time scale we integrate these new results with existing magnetostratigraphic biostratigraphic and geochronological results from the karoo basin with particular emphasis on the controversy over zircon age data reported from the underlying ecca group

radioisotopic and biostratigraphic constraints on the classical middle upper permian succession and tetrapod fauna of the moscow syneclise russia

evidence from luminescence for late pleistocene formation of calcareous aeolianite kurkar and paleosol hamra in the carmel coast israel abstract calcareous aeolianite kurkar and red loamy paleosol hamra units form ridges in the northern coastal plain of israel the kurkar ridges with hamra units have been thought to be indicators of past sea levels and of palaeoclimate though there has been no clear chronology that could correlate units from one ridge to another or to global palaeoclimate and sea level change we obtained detailed stratigraphy and luminescence ages for the kurkar and hamra units that range from 35 to 101 ka indicating coeval formation of these units during the late pleistocene independent dating suggests that hamra and similar loamy soils formed at 45 to 130 ka in the habonim quarry site at the eastern ridge when kurkar that has been dated by us to 50 67 ka was deposited in the coastal trough showing facies changes from west to east the youngest ages for exposed kurkar in the dor islet at the coastal ridge 35 and 38 ka are close to the 35 ka age obtained independently for the upper kurkar near atlit at the eastern ridge at that time when kurkar was deposited and cemented on the top of both ridges a hamra dated by us to 37 ka formed in the coastal trough our results indicate that kurkar accumulated along the coastal plain at different time intervals throughout the late pleistocene and that its deposition was not necessarily associated with high sea levels moreover our data as well as previous research suggest that hamra also formed at different periods sometimes synchronous with kurkar and its formation is therefore not related to any particular climatic events

late pleistocene carbonate aeolianites on mallorca western mediterranean a luminescence chronology abstract coastal outcrops of upper pleistocene deposits in north eastern mallorca balearic islands spain have been examined and a chronological framework established using optically stimulated luminescence osl dating the outcrops record a complex interaction between aeolian colluvial and alluvial fan deposition that result in a variable stratigraphical architecture dating and facies analysis make it possible to identify four aeolian activity episodes during mis 5c b 4 and 3 and also add to the understanding of the environmental history of north eastern mallorca over the last 100 ka the new data suggest enhanced aeolian transport and dune formation during cold climatic intervals when sea level was low sediment supply exposed marine carbonate sediment was high winter windiness was high and vegetation on coastal plains at a minimum

dust rains in mallorca western mediterranean their occurrence and role in some recent geological processes abstract dust rains were observed in palma de mallorca island of mallorca western mediterranean on 253 days in the 22 year period from 1982 to 2003 these and other data from the western mediterranean show that dust rains are on the increase most occur in the warmest season of the year meteorological conditions associated with this phenomenon combine hot advection from the south at low tropospheric levels with southwest winds associated with a depression in the middle troposphere dry deposition of dust often in aggregates 40 300 m across is occasionally observed analysed samples are silty and mainly composed of quartz and kaolinite they also contain minor proportions of feldspars and palygorskite which do not occur as rock forming minerals in the balearic islands comparisons of the dusty rainwater samples with soils and recent marine and karstic sediments suggest that dust deposition is an important sedimentary process in the balearic islands

a lithostratigraphic and magnetostratigraphic framework in a geochronologic context for a purported permian triassic boundary section at old west lootsberg pass karoo basin south africa

magnetostratigraphy of permian triassic boundary sequences in the cis urals russia no evidence for a major temporal hiatus during the last five years there has been considerable doubt over the age of the continental uppermost permian russian stages the kazanian and tatarian traditionally they have been regarded as late permian but were re dated as middle permian in the 2004 international time scale despite fossil evidence that the tatarian at least is late permian these debated ages are tested by magnetostratigraphic study of five sections spanning the permian triassic boundary ptb of the se urals in the orenburg region of russia the upper permian and lower triassic of this region have a well documented vertebrate fauna whose evolution has a significant bearing on our understanding of the ptb mass extinction event if the tatarian is viewed as mid permian then the late permian in russia is marked by a 9 10 ma stratigraphic gap the palaeomagnetic data yield a distinct series of polarity zones that provide clear local and regional correlation and are readily tied to a recently compiled global magnetostratigraphic record on the basis of this correlation the sampled sections span the upper guadalupian to induan stages without any obvious break so confirming the traditional view that the tatarian is late permian in age anomalies in the magnetic inclination are consistent with sediment compaction inclination shallowing a common phenomenon of red beds but declination anomalies between these sites and elsewhere in russia may suggest localised vertical axis rotation

no gap in the middle permian record of terrestrial vertebrates during the permian tetrapods showed a major transition from basal synapsid dominated faunas in the first half to therapsid dominated faunas in the second the transition was significant in marking the beginning of richer and more complex communities a precursor to modern terrestrial ecosystems this changeover may have been gradual or abrupt but its study has been complicated by the postulated occurrence of a substantial hiatus in the fossil record termed olson9s gap which obscured the nature of the turnover new evidence from redating of key tetrapod bearing units of the american southwest and european russia confirms that there is no gap in the fossil record of permian tetrapods indeed evidence for substantial sampling bias in the permian tetrapod fossil record as a whole is queried

sedimentology and progressive tectonic unconformities of the sheetflood dominated hell s gate alluvial fan death valley california abstract the hell s gate alluvial fan of northern death valley has an area of 49 5 km2 a radius of 11 8 km and a smooth 5 3 sloping surface interrupted by shallow

upper permian vertebrates and their sedimentological context in the south urals russia fossil fishes and tetrapods amphibians and reptiles have been discovered at 81 localities in the upper permian of the southern urals area of european russia the first sites were found in the 1940s and subsequent surveys have revealed many more broad scale stratigraphic schemes have been published but full documentation of the rich tetrapod faunas has not been presented before the area of richest deposits covers some 900 000 km2 of territory between samara on the river volga in the nw and orenburg and sakmara in the sw a continental succession some 3 km thick of mudstones siltstones and sandstones deposited on mudflats and in small rivers flowing off the ural mountain chain span the last two stages of the permian kazanian tatarian the succession is divided into seven successive units of kazanian kalinovskaya osinovskaya and belebey svitas in succession and tatarian age which is further subdivided into the early tatatian urzhumian gorizont bolshekinelskaya and amanakskaya svitas in succession and the late tatarian severodvinian vyazovskaya and malokinelskaya svitas of equivalent age and vyatkian gorizonts kulchumovskaya and kutulukskaya svitas of equivalent age this succession documents major climatic changes with increasing aridity through the late permian the climate changes are manifested in changing sedimentation and the spread of dryland plants and peak aridity was achieved right at the permo triassic ptr boundary coincident with global warming uplift of the urals and extinction of land plants led to stripping of soils and massive run off from the mountains these phenomena have been identified at the ptr boundary elsewhere south africa australia and this may be a key part of the end permian mass extinction the succession of late permian fish and tetrapod faunas in russia documents their richness and diversity before the mass extinction the terminal permian kulchomovskaya and kutulukskaya svitas have yielded respectively some 6 and 13 species of fishes sharks bony fishes lungfishes and 11 and 14 species of tetrapods aquatic amphibians herbivorous and carnivorous reptiles of all sizes up to the hippo sized pareiasaurs and sabre toothed gorgonopsians immediately following the end permian environmental catastrophe earliest triassic faunas consisted only of a few fish taxa and small aquatic tetrapods in low diversity low abundance assemblages

shift in the paradigm for gssp boundary definition abstract for over 200 years the use of biotic events as the basis for the establishment of chronostratigraphic boundaries has been the only approach successfully utilized for international and national chronostratigraphy the traditional biostratigraphic method provides relatively high resolution averaging 1 ma or sometimes less this biochronological evolutionary approach to the global boundary stratotype section and point gssp utilizes biotic primary markers pm with a few exceptions encompasses the integrated pm and other non pm markers as the general principles for defining gssp boundaries and is a reasonably reliable mechanism for global correlation and a relatively stable international geologic time scale igts the biotic pm s however possessed several serious restrictions the nature of biological taxonomy climatic sedimentary environmental and directly applicable within the tropics subtropics only biotic evolution and radiogenic isotopes are the only systems in geologic time that encompass the direction of time the latter possessed less restrictions than the former the recent tendency to define gssp s utilizing magnetic chrons climatic events and geochemistry may work in the cenozoic but is useless in the mesozoic and older sediments because their cyclic nature repeatedness and the need for a second directional in time index biostratigraphic or radioisotopic to place the pm in the right position within the scale i propose here to utilize volcanic ash beds as the best primary marker in geologic chronostratigraphy the u pb system is one of the most dependable of the geochronologic systems because it relies on a simple and non interpretive radioisotopic decay constant the ash bed gssp as a lithological horizon is universal for the gssp definition and can be correlated as an age in any facies marine lagoon and continental regardless of paleoclimatic zones paleoceanographic geochemical and most other geological factors even moderate level metamorphism 900 does not affect the u pb dating of zircons the gssp at the base of a volcanic ash bed primary marker could be established in a short working time and these ash beds can be integrated with the existing as well as new biostratigraphic geochemical magnetostratigraphic and astronomical data secondary markers to create a robust accurate and highly useable time scale several potential gssp s that could be established with the volcanic ash beds close to the traditional and or historical boundaries serve as examples for this approach and include devonian carboniferous moscovian kasimovian kasimovian gzhelian and sakmarian artinskian boundaries

middle pleistocene magnetostratigraphy and susceptibility stratigraphy data from a carbonate aeolian system mallorca western mediterranean abstract this study shows that successions of pleistocene carbonate aeolian deposits can be placed successfully in a geochronologic framework using magnetostratigraphic and susceptibility stratigraphic analysis supplemented by luminescence dating studies of wave cut platforms and biostratigraphic evidence the investigated aeolian system covers a significant part of southernmost mallorca and is exposed in impressive coastal cliff sections at the study site at els bancals the aeolian system has a maximum thickness of 16 m and is composed of alternating dark red colluvial deposits and greyish red aeolian dune and sand sheet deposits forming seven cyclostratigraphic units each cyclostratigraphic unit represents landscape stabilisation colluviation and soil formation followed by dunefield development when marine carbonate sand was transported far inland by westerly or north westerly winds the aeolian system is located on top of a wave cut marine platform 12 14 m a s l this platform probably formed during a sea level highstand in marine isotope stage mis 11 427 364 ka and renewed marine activity probably later in mis 11 is indicated by the formation of beach deposits two sections at els bancals were sampled for a paleomagnetic study additional samples were taken to detect variations in magnetic susceptibility ms the characteristic remanent magnetisation has been recovered for the most part of the succession in spite of diagenetic overprinting there is evidence for two probably three reversal polarity excursions possible connected to the levantine cr1 and cr0 biwa iii episodes if this correlation is correct the sampled succession represents a time interval in the middle pleistocene between ca 410 and ca 260 ka this age estimate is supported by the ms study and by luminescence dates of 333 70 ka aeolianite from lower part of the succession and 275 23 ka aeolianite from the top of the succession the nature of the succession suggests deposition during alternating warm and moist colluvial deposition soil formation and cold dry and windy conditions dunefield formation the susceptibility signal can be correlated with the insolation signal at 65 n suggesting that environmental variation on mallorca was linked to orbitally forced climate change and it seems that aeolian activity and dunefield formation were linked to glacial or stadial periods

palaeoclimate interpretation of stable isotope data from lake sediment archives the isotope composition of authigenic and biogenic carbonates and diatom silica are commonly used as palaeoclimate proxies from lake sediments this article reviews the controls on the isotope composition of lacustrine skeletal and non skeletal deposits and illustrates how stable isotope studies contribute to an understanding of changes in temperature precipitation patterns evaporation and the carbon cycle it highlights the differences in the palaeoclimate potential of a wide range of lakes ranging from open to closed lake basins a large number of the case histories but not all are drawn from studies of temperate lakes from europe large closed lake systems in the tropics and elsewhere lose water predominantly through evaporation and contain sediments with variable and generally high 18o values fluctuations in the isotope composition of authigenic or biogenic minerals are mainly a function of long term changes in the precipitation evaporation ratio in contrast small open lakes which have a degree of through flow typically contain sediments with 18o values that vary by no more than a few these variations are generally ascribed to variations in temperature or the isotope composition of precipitation p from which either an annual or seasonally specific signal can be gained these types of lakes are common in northern europe and at high altitudes the interpretation of isotope data from a lacustrine succession requires a knowledge of the local processes that might control and modify the signal their effects need to be quantified and a robust calibration using the modern lake system is necessary to establish the relationship between the measured signal the isotopic composition of the host waters and climate

upper permian magnetic stratigraphy of the lower beaufort group karoo basin abstract we carried out a magnetostratigraphic and geochronological study of late permian sediments in the karoo basin of the western cape province south africa a continuous 700 m thick section of deltaic sediments of the upper waterford formation uppermost ecca group and the fluvial sediments of the abrahamskraal formation lowermost beaufort group were sampled at the meter scale u pb dating of zircons from interbedded volcanic ash beds by ion microprobe shrimp provided absolute age constraints on the age of the sedimentary rocks paleomagnetic analysis reveals a partial overprint of the natural remanent magnetization nrm that is tentatively ascribed to the emplacement of the karoo large igneous province in the western cape region during the middle jurassic a stable component of the nrm was found at temperatures higher than 450 c and was interpreted as a characteristic remanent magnetization chrm acquired during deposition supported by a positive reversals test for this dual polarity chrm the virtual geomagnetic pole position for the waterford and abrahamskraal formations computed from the average chrm direction is in general agreement with the late permian directions for stable gondwana a significantly different average inclination and thus paleomagnetic pole position is obtained by correcting the inclination shallowing error by the elongation inclination method tauxe and kent 2004 the presence of both normal and reversed polarity zones indicate deposition after the end of the kiaman superchron moreover the polarity sequence is in good agreement with the illawarra sequence of steiner 2006 our results indicate a capitanian late guadalupian age for the abrahamskraal fm in agreement with the late permian age based on presence of glossopteris flora and dicynodont fauna traditionally assigned to the fluvial lacustrine sediments of the beaufort group however the u pb zircon ages of ca 264 268 ma suggest an age of 269 ma for the top of the kiaman superchron

a structural outline of the serra de tramuntana of mallorca balearic islands abstract the structural and stratigraphic aspects of the balearic islands are described by outlining the geology of the serra de tramuntana this range is part of the southeastern margin of the valencia trough and has the typical features of thrust tectonic areas a stratigraphic column a structural map and three cross sections show the main features of this range thrusts dip to the southeast and are arranged in an imbricate system with a transport direction to the nw the thrusts recorded involve upper paleozoic to middle miocene rocks imbricates bearing thin slices and duplexes developed where thin sequences with pronounced competency contrasts exist folds are also present they usually trend ne sw except in local areas where they are interpreted as being associated with oblique ramps fold axes plunge sub horizontally and folds face the northwest thrust displacements of up to 10 km are deduced from the existence of klippes and windows and shortening of around 50 is deduced from a comparison of deformed and restored cross sections the onset of the main contractional event is pre miocene probably late oligocene in age but major thrust emplacement occurred during the middle miocene the widespread occurrence of compression structures in the balearic islands developed from late oligocene to middle miocene put strong constraints on the models explaining the origin of both the valencia trough and the algerian basin the first must be considered at least in part as the balearic foreland basin and the second could be superimposed on the internal zone of the western mediterranean orogenic belt

tyrrhenian coastal deposits from sardinia italy a petrographic record of high sea levels and shifting climate belts during the last interglacial isotopic substage 5e abstract detailed petrographic and sedimentological analysis of tyrrhenian coastal deposits from four sites in sardinia provides new data about climate and sea level changes during the early part of the last interglacial isotopic substage 5e and shows that facies analysis is not only useful for the identification of ancient depositional environments but also represents a powerful tool for evaluating past climatic conditions and sea level forcing mechanisms two shallowing upward sequences sensu ward w c brady m j 1979 strandline sedimentation of carbonate grainstones upper pleistocene yucatan peninsula mexico am assoc pet geol bull 63 362 369 commonly separated by an erosion surface and displaying complex geometric relationships occur above modern sea level at several locations along the shorelines of sardinia these sequences include upper shoreface to backshore deposits and were formed during separate sea level highstands attributed to isotopic substage 5e our recent revision of these deposits indicates that each sequence presents distinctive petrographic characteristics the older succession essentially contains mixed calcarenites rich in quartz grains and lithic fragments whereas the younger sediments are dominated by carbonate bioclasts such as red algae coral and mollusk fragments both units apparently accumulated in a similar depositional setting but during different climatic regimes the petrography of the lower unit reflects a temperate humid period characterized by increased weathering and continental erosion whereas the composition of the upper one suggests a dryer and possibly warmer climate favoring active carbonate production the disparity in petrographic composition between sequences probably records the migration of atmospheric circulation cells i e a shift of climate belts before and after the 128 ka insolation maximum our climatic data are coherent with the calculated insolation curves for isotopic substage 5e and thus support the milankovitch hypothesis for the origin of pleistocene climates in contrast our sedimentological data clearly show the occurrence of two distinctive highstands of sea level during this time period which does not agree with the hypothesis it follows that the relation between orbitally induced insolation variations climate and sea level is not necessarily straightforward

ammonoid stratigraphy and sedimentary evolution across the permian triassic boundary in east greenland east greenland is a classical area for the study of the permian triassic transition and the succession is one of the most expanded in the world new ammonoid data from the wordie creek formation have allowed us to better reconstruct the history of the east greenland basin from semi isolated basins with an endemic fauna during latest permian earliest triassic h triviale h martini zones time to well connected open marine shelf basins during the early triassic m subdemissum o commune w decipiens and b rosenkrantzi zone times the east greenland zonation can be correlated with boreal zonations in arctic canada svalbard and northeastern asia it allows precise relative dating and correlation of important events across the permian triassic boundary the new ammonoid data indicate that deposition was continuous across the permian triassic boundary and developed as a marine mudstone mudstone contact in basinal areas of hold with hope northern and southern jameson land correlation of the ammonoid stratigraphy with the fad of hindeodus parvus which defines the base of the triassic in global stratotype section and point gssp in meishan china suggests that the hypophiceras triviale zone is to be referred to the uppermost permian whereas the h martini zone is lowermost triassic accordingly the end permian marine and terrestrial extinctions and associated isotope changes as well as the subsequent adaptive radiations in east greenland took place in latest permian time new boreal faunas and floras were well established and diversified in the hypophiceras triviale zone prior to the beginning of the triassic and the permian triassic boundary in its present definition is no longer reflecting major changes in the earth system it would have been fortunate if a gssp were defined in a protracted section at a point of major environmental perturbations marked by isotope excursions chemical anomalies and mass extinction rather than in the strongly condensed section like meishan at a point which post dates all significant events

eustatic and climatic controls on the development of the wahiba sand sea sultanate of oman aeolian sand sea accumulations can serve as valuable archives of climate change in continental environments the wahiba sand sea is situated at the northern margin of the area presently affected by indian summer monsoon circulation and it records environmental changes associated with this major climatic boundary over the last 160 000 years the internal stratigraphy and evolution of the sand sea is investigated using a combination of outcrop borehole seismic and luminescence data proximity to the indian ocean means that the sand sea succession shows the influence of sea level changes on the sedimentary architecture and composition of the dune deposits during the last two glacial periods low global sea level was associated with a high input of bioclastic grains reflecting the significance of subaerially exposed shelf areas as one of the main sources of aeolian sediment the onset of aeolian sediment transport and deposition was related to the breakdown of stabilizing vegetation during arid periods that equate with sea level lowstands the preservation of aeolian sediments by the formation of supersurfaces and associated palaeosoils took place during times of increased wetness and elevated groundwater tables this interplay of constructive and destructive periods greatly influenced the sedimentary architecture oscillations of wet and dry periods between 160 000 and 130 000 years and 120 000 105 000 years ago are attributed to the evolution of a wet aeolian system younger periods of aeolian deposition around and after the last glacial maximum were characterized by dry aeolian conditions no soil horizons developed during these times

improved methodology and new thermoluminescence ages for the dune sequence in south east south australia abstract our thermoluminescence dating technique for quartz extracted from late pleistocene sediments has been improved by the addition of a 33 h 160 c preheat before measurements this yields better plateaux which now encompass the region known as the 325 c tl peak this is consistent with the prediction from isothermal decay studies of the lifetime at ambient temperature of the traps responsible for this peak the preheat does not help resolve problems associated with dose responses above 600 gy some details of the dose response are shown to be better understood with the aid of 3 d tl spectra the improved method has been applied to one former and seven new samples from the stranded beach dune sequence in south east south australia the five ages obtained for the main dune sequence range from 95 6 to 725 100 ka and all are consistent with the expected ages

is the vertebrate defined permian triassic boundary in the karoo basin south africa the terrestrial expression of the end permian marine event the end permian extinction records the greatest ecological catastrophe in earth history the vertebrate fossil record in the karoo basin south africa has been used for more than a century as the standard for understanding turnover in terrestrial ecosystems recently claimed to be in synchrony with the marine crisis workers assumed that systematic turnover at the dicynodon assemblage zone boundary followed by the appearance of new taxa directly above the base of the lystrosaurus assemblage zone is the continental expression of the end permian event and recovery to test this hypothesis we present the first highprecision age on strata close to the inferred permian triassic boundary a u pb isotope dilution thermal ionization mass spectrometry zircon age of 253 48 0 15 ma early changhsingian is from a silicified ash layer 60 m below the current vertebrate defined boundary at old lootsberg pass southern south africa this section yields newly discovered plants and vertebrates and is dominated by a normal polarity signature our collective data suggest that the dicynodon lystrosaurus assemblage zone boundary is stratigraphically higher than currently reported and older than the marine extinction event therefore the turnover in vertebrate taxa at this biozone boundary probably does not represent the biological expression of the terrestrial end permian mass extinction the actual permian triassic boundary in the karoo basin is either higher in the katberg formation or is not preserved the currently accepted model of the terrestrial ecosystem response to the crisis both in this basin and its extension globally requires reevaluation

formation of aeolian dunes on anholt denmark since ad 1560 a record of deforestation and increased storminess abstract sand dunes on the island of anholt denmark in the middle of kattegat form a relatively barren temperate climate aeolian system locally termed the desert the dunes have developed on top of a raised beach ridge system under the influence of dominant winds from westerly directions they are relatively coarse grained with an average mean grain size of 480 m the last phase of aeolian activity and dune formation on anholt started after ad 1560 when the local pine forest was removed historical sources report intense sand mobilization in the 17th century and new optically stimulated luminescence osl dates indicate that dune formation continued until the end of the 19th century this period of sand drift and dune formation took place during the later part of the little ice age which is characterized by increased summer storminess in large parts of nw europe dune stabilization in the beginning of the 20th century probably records a temporary decrease in storminess ground penetrating radar mapping of the internal structures in two dunes in the western part of the desert a parabolic dune and a linear dune indicates the importance of north westerly storm winds during dune formation

early wuchiapingian cooling linked to emeishan basaltic weathering abstract the last glaciation during the late paleozoic ice age commenced at around the guadalupian lopingian g l boundary and is synchronous with the emplacement of the emeishan large igneous province using ca tims zircon u pb dating we obtained an age of 259 51 0 21 ma for the uppermost tuff from the puan volcanic sequence in the eastern emeishan large igneous province constraining the timing of emeishan volcanism and providing another candidate age for the g l boundary in addition we determined an age of 259 69 0 72 ma for a basal claystone in the immediately overlying longtan formation from a drill core section in southwest south china these ages along with source weathering trends of mudstones from the lower longtan formation and compiled paleotemperature records indicate an earliest wuchiapingian cooling coinciding with the onset of the last permian glaciation this global cooling is associated with positive shifts in both organic and carbonate carbon isotopic records and likely a decrease in atmospheric pco2 a hypothesised causal linkage is proposed in which the rapid post eruptive basaltic weathering of the emeishan province in an equatorial humid belt may accelerate the atmospheric co2 consumption and lead to climate cooling our work supports the long term climate cooling effects of large igneous provinces

last interglacial fossil elephant trackways dated by osl aar in coastal aeolianites still bay south africa abstract the impressive pleistocene coastal aeolianite exposures in sea cliffs east of still bay on the west southern coast of south africa host a rich archive of fossil mammalian trackways including the african elephant loxodonta africana neither the ichnofossils nor their host sediments have been described in any detail and chronologies remained uncertain this paper presents a new optically stimulated luminescence osl and amino acid racemisation aar chronology the first joint application of osl aar dating in south africa this provides a temporal framework for assessing the palaeoenvironmental significance of dune sedimentation patterns pedogenesis and ichnology the pleistocene aeolianite exposures at still bay represent the recently eroded remnants of a dune cordon mainly built by coalesced parabolic dune systems sedimentary facies are dominated by large scale planar cross stratification formed by foreset progradation in the nose and trailing arms of the dunes and low angle bedding chiefly representing sedimentation in low relief interdune terrain the main dune building wind regime was westerly associated with cyclonic polar frontal systems as at the present time the osl and aar dating demonstrate ages ranging from mis 5e to 5b and termination of pleistocene aeolian sedimentation at 90 ka the pleistocene aeolianite is separated from the overlying holocene dunes dated to 8 ka by a major hiatus recorded by a horizon of intense pedogenesis elephant footprints were seen in profile as casts on the underside of beds and as natural impressions the taphonomic processes controlling the morphology and preservation of these unique ichnofossils were found to be complex the presence of loxodonta africana at still bay represents the southernmost occurrence of this species recorded to date and possibly a closer proximity of woodland during mis 5 this and other observations may indicate a higher moisture regime than at present there is no available evidence that the elephants were predated by contemporary middle stone age people

silicic ash beds bracket emeishan large igneous province to 1 m y at 260 ma this research was supported by the open fund plc201404 of state key laboratory of oil and gas reservoir geology and exploitation chengdu university of technology the national natural science foundation of china 41502109 project funded by china postdoctoral science foundation 2015 m582528 and the fundamental research funds for the central universities chengdu university of technology

exploring the method of optical dating and comparison of optical and 14c ages of late weichselian coversands in the southern netherlands a study was made of the applicability of three different techniques for equivalent dose de determination in the optical dating of quartz the single aliquot regenerative dose technique sar the single aliquot additive dose technique saad and the multiple aliquot additive dose technique maad for this purpose quartz grains were extracted from a sequence of upper pleniglacial to late glacial coversands exposed at the locality of ossendrecht in the southwestern netherlands a site for which both radiocarbon and earlier luminescence dates are available providing independent age control upon testing the different assumptions underlying each of the three osl techniques investigated the sar protocol was found to be the technique of choice the optical ages obtained with this protocol were in good agreement with the chronostratigraphical position of the sediments investigated and with the available chronostratigraphical information on the same and equivalent deposits this confirms the suitability of the sar technique for dating coversands furthermore a small laboratory intercomparison of sar based de determinations yielded results that were in fair overall agreement copyright 2004 john wiley sons ltd

new data on the pleistocene of mallorca abstract stratigraphic geomorphologic and isoleucine epimerization studies at 15 sites in mallorca define four aminozones a c e and f g of increasing age that are related to transgressive regressive marine cycles from the holocene to the mid pleistocene calibration of aminozone e glycymeris aile ile mean from all sites 0 41 0 03 n 38 is provided by a 129 7 ka u series coral age on cladocora caespitosa from son grauet of the younger aminozones a relates to the holocene transgression and aminozone c to a mid to late isotopic stage 5 event 90 15 ka revealed only by supralittoral eolianites assigning an age to the older poorly resolved aminozones f and g called f g in this case is uncertain without supporting radiometric data but an age of 180 ka can be assigned to these aminozone s f g based on a kinetic model and other examples in the mediterranean several deposits previously dated u series molluscs between 75 and 300 ka appear to belong to the last interglacial complex stage 5 and aminozone e a proposed revision of the positive sea level history of mallorca shows multiple minor oscillations during the major last interglacial cycle stage 5 and two mid pleistocene sea levels one lower than present and the other at about 14 m a s l

new quartz sar osl ages from the stranded beach dune sequence in south east south australia a sequence of stranded coastal barriers in south east south australia preserves a record of sea level variations over the past 800 ka huntley et al quat sci rev 12 1993a 1 quat sci rev 13 1994a 201 attempted to test thermoluminescence tl dating methods and found good agreement between quartz tl ages with independent ages for these dunes we investigate the accuracy of the single aliquot regenerative dose sar procedure radiat meas 32 2000 57 over an extended age range of 0 250 ka by comparing sar osl ages determined on quartz extracts from these dunes with the existing chronology we show that robe ii range is 60 ka and that robe iii is 100 ka old not surprisingly the osl ages increase monotonically from the robe ii range to the west naracoorte range for the younger dunes 240 ka the sar osl ages agree with the expected ages within 1 errors whereas for the older dunes the sar ages are consistent with independent ages within 2 error limits we consider these results to be very promising and lend support to the large number of quartz sar osl ages being presented in the literature where such comparisons with independent chronology are not usually possible

abrupt temperature changes in the western mediterranean over the past 250 000 years a continuous high resolution western mediterranean sea surface temperature sst alkenone record spanning the past 250 000 years shows that abrupt changes were more common at warming than at cooling during marine isotope stage mis 6 sst oscillated following a stadial interstadial pattern but at lower intensities and rates of change than in the dansgaard oeschger events of mis 3 some of the most prominent events occurred over miss 5 and 7 after prolonged warm periods of high stability climate during the whole period was predominantly maintained in interglacial interstadial conditions whereas the duration of stadials was much shorter

a geomagnetic polarity timescale for the permian calibrated to stage boundaries the reverse polarity kiaman superchron has strong evidence for at least three or prob ably four normal magnetochrons during the early permian normal magnetochrons are during the early asselian base ci1r 1n at 297 94 0 33 ma late artinskian ci2n at 281 24 2 3 ma mid kungurian ci3n at 275 86 2 0 ma and roadian ci3r an at 269 54 1 6 ma the mixed polarity illawarra superchron begins in the early wordian at 266 66 0 76 ma the wordian capitanian interval is biased to normal polarity but the basal wuchiapingian begins the beginning of a significant reverse polarity magnetochron lp0r with an overlying mixed polarity interval through the later lopingian no significant magnetostratigraphic data gaps exist in the permian geomagnetic polarity record the early cisuralian magnetochrons are calibrated to a succession of fusulinid zones the later cisuralian and guadalupian to a conodont and fusulinid biostratigraphy and lopingian magnetochrons to conodont zonations age calibration of the magnetochrons is obtained through a bayesian approach using 35 radiometric dates and 95 confidence intervals on the ages and chron durations are obtained the dating control points are most numerous in the gzhelian asselian wordian and changhsingian intervals this significant advance should provide a framework for better correlation and dating of the marine and non marine permian

morphology and architecture of a late pleistocene cliff front dune mallorca western mediterranean cliff front dunes are a common coastal feature but this is the first time that the structures indicative of their formation are documented a late pleistocene cliff front dune in southern mallorca has been studied owing to early lithification of the calcarenite its morphology is well preserved the dune occurs in front of a curved near vertical coastal cliff but the bedform cannot be classified as a fixed echo dune the dune grew with time and its brinkline gradually moved closer to the cliff front in the final stage of evolution the top of the dune reached a height of at least 23 m the dune is composed of wind ripple strata these strata are arranged in critical to supercritical climbing dune cross stratification recording its growth stages the angle of climb of the dune increases toward the cliff and reaches 50 the morphological features of cliff front dunes result from both cliff slope and whether the cliff front is curved or straight

further thermoluminescence dates from the dune sequence in the southeast of south australia abstract our thermoluminescence dating technique has been applied to several new samples from the remarkable sequence of stranded beach dunes in southeast south australia that were formed during the past 800 ka we show that robe iii is probably 100 ka as suggested by schwebel and not 80 ka as we suggested earlier a sample from the west dairy dune is shown to belong to 18 o stage 7 in accordance with schwebel s original suggestion and not stage 5 as he suggested later a new west naracoorte sample yielded acceptable data and an age consistent with formation just after the brunhes matuyama magnetic reversal at 780 ka as required by palaeomagnetic measurements two more samples from the woakwine dune show that our reproducibility is consistent with our derived errors

disruption of playa lacustrine depositional systems at the permo triassic boundary evidence from vyazniki and gorokhovets on the russian platform abstract permo triassic sections at vyazniki and gorokhovets provide evidence on terrestrial events at or close to the permo triassic boundary the time of the largest ever mass extinction the sedimentary succession records the overrun of a muddy playa lacustrine depositional system by major channel belts transporting sand grade sediments biostratigraphy of sections at vyazniki and gorokhovets zhukov ravine shows that this event occurred either at the very end of the permian or 8 m above in the sections the timing and nature of this event which records increased sediment flux from the ural mountains is closely comparable with that from the southern uralian foreland basin the vyazniki and gorokhovets sections are 800 km from the mountain front and in a separate depositional basin which strengthens the case that increased sediment flux from the urals at the permo triassic boundary is related to devegetation of upland catchments increasing sediment yield and a switch toward low frequency but high magnitude discharge events increasing sediment delivery the interbedding of fluvial and aeolian deposits provides further evidence for climatic instability and extremes in the early triassic supplementary material detailed reports on the ostracodes and fossil fish remains from the zhukov ravine sections are available at http www geolsoc org uk sup18402

synchrony of southern hemisphere late pleistocene arid episodes a review of luminescence chronologies from arid aeolian landscapes south of the equator abstract luminescence dating chronologies that have been reported in various studies of late pleistocene arid land aeolian sequences from australia southern africa and south america are reviewed with the objective of determining whether any pan hemispheric synchroneity existed in the timing of landscape responses to late quaternary climate changes south of the equator the results broadly show that contemporaneous regional arid land aeolian activity occurred in australia and southern africa during the periods ca 65 41 and 36 9 ka the relatively limited luminescence data from the south american subcontinent also point to recurrent arid land aeolian deposition between 63 and 8 ka with increasing frequency in the period ca 32 8 ka records from all three continents suggest a period of reduced aeolian activity between 41 and 36 ka overall the data are indicative of extensive landscape instability of the low to mid latitudes in the southern hemisphere during the last glacial period particularly at the last glacial maximum which accords with mainstream opinions aeolian activity during the holocene has generally been localised the rigour with which comparisons can be made between the different studies however is constrained by variations in practices between laboratories and changes that have occurred to luminescence dating procedures over the years

integrative timescale for the lopingian late permian a review and update from shangsi south china abstract the lopingian is the uppermost series of the paleozoic and it is bracketed by two major biological events including the pre lopingian crisis and the end permian mass extinction epme a high resolution temporal framework is essential to understand the patterns and causes of the extinction lopingian strata of south china have been intensively studied because three gssps have been defined in the region based on the review and updates to data from the shangsi section as well as correlation with the meishan section the time framework for the lopingian is revised including biostratigraphy chemostratigraphy magnetostratigraphy cyclostratigraphy and geochronology the temporal framework is constrained by both precise geochronologic data and a high resolution conodont succession and provides the possibility that the current high resolution marine international standard can also be applied to nonmarine strata by means of geochronology magnetostratigraphy and cyclostratigraphy the entire lopingian high resolution conodont succession is for the first time since the lopingian series was adopted as the international standard recognized at a single section in south china and the succession correlates very well with the lopingian gssp sections at penglaitan and meishan the permian triassic boundary ptb of the shangsi section is constrained to the basal 6 cm interval of bed 28b in view of ammonoids bivalves conodonts u pb ages and the epme the mass extinction interval is between bed 27 and lower bed 28a according to the epme pattern at the shangsi section and the alternative interval between extinct permian species and new triassic species is from upper bed 28a to lower bed 28b unitary association ua analysis of lopingian conodonts reveals 15 unitary association zones uazs based on seven important lopingian sections of south china most of the uazs correlate well with the standard biozonation except for uaz 3 to uaz 5 and uaz 12 the correspondence between uazs and standard conodont biozones at the shangsi section provides a practical example to understand controls on conodont uaz determination the lopingian conodont succession is temporally calibrated by geochronologic ages identified 405 kyr eccentricity cycles and a monte carlo analysis at the shangsi and meishan sections updated ages for the base of the lopingian and base of the changhsingian are provided

volcanism mass extinction and carbon isotope fluctuations in the middle permian of china the 260 million year old emeishan volcanic province of southwest china overlies and is interbedded with middle permian carbonates that contain a record of the guadalupian mass extinction sections in the region thus provide an opportunity to directly monitor the relative timing of extinction and volcanism within the same locations these show that the onset of volcanism was marked by both large phreatomagmatic eruptions and extinctions amongst fusulinacean foraminifers and calcareous algae the temporal coincidence of these two phenomena supports the idea of a cause and effect relationship the crisis predates the onset of a major negative carbon isotope excursion that points to subsequent severe disturbance of the ocean atmosphere carbon cycle

radioisotopic calibration of the guadalupian middle permian series review and updates abstract four high precision u pb ca idtims dates for the roadian lower guadalupian of 274 0 0 12 and 273 1 0 1 ma and for the wuchiapingian lower lopingian of 260 16 0 39 and 258 14 0 20 ma were obtained from permian tuff beds in the periphery of the okhotsk massif n e russia the beds are well constrained within the local lithostratigraphic and regional biostratigraphic framework besides regional bivalves and brachiopod faunas the ammonoid sverdrupites harkeri occurs close to the recovered roadian tuffs this ammonoid provides direct correlation of the tuffs with the kazanian stage on the russian platform and the roadian stage in the canadian arctic where the conodont index species of the roadian stage jinogondolella nankingensis gracilis and sverdrupites harkeri and other roadian ammonoids are documented from the assistant formation our review of the kungurian roadian wordian successions in the main well studied regions suggests that the base of the roadian stage should be extended down to approximately 277 ma and the roadian wordian boundary should be placed at approximately 271 ma the new calibration of the roadian stage reduces the duration of the enormously long kungurian stage from about 10 myr approximately to 6 0 6 5 myr if the proposed calibration is correct the duration of guadalupian series would be almost twice as great as in the previous estimates our results also suggest a possible correlation of the p3 alpine glacial event in the eastern australia with the wordian and possible uppermost roadian stages this p3 event corresponds with the disappearance of ammonoids and conodonts in the upper roadian and wordian in high latitudes regions i e n e russia russian and canadian arctic and australia perhaps due to extreme cooling of these areas the new radioisotopic ages in the okhotsk massif and surrounding regions improve the numerical calibration of the palynological zonation in the eastern australia and provide a direct correlation of the regional biostratigraphic brachiopod and bivalve zonation of n e russia with the international geologic time scale this zonation becomes a solid and reliable regional correlation tool within the vast territory from taymyr and east siberia to entire n e russia and transbaikalia

conodont sr ca and δ18o record seawater changes at the frasnian famennian boundary abstract the oxygen isotopic composition 18 o p and strontium calcium sr ca p ratios have been measured in late devonian conodonts palmatolepis sp from contemporaneous sections at coumiac france and m rirt morocco the sequences encompass two anoxic horizons the lower kellwasser lkw and upper kellwasser ukw events with the top of the ukw coinciding with the mass extinction at the frasnian famennian boundary the genus palmatolepis survived the faunal crisis but exhibited plastic responses to the environmental changes which are recorded in the evolution of shape during the anoxic events the present study demonstrates that shape 18 o p and sr ca p values of conodonts are correlated in both localities excluding diagenesis as the driving process for the measured 18 o p and sr ca p values the conodonts 18 o p and sr ca p values are correlated in both localities and distributed into either a pre crisis and crisis group using the relationships between the 18 o p and sr ca p values we estimate that the variation of the seawater sr ca ratio during the frasnian famennian mass extinction was of about 20 its initial value this drastic decrease of the seawater sr ca ratio is discussed in the light of the reef demise that occurred during the faunal crisis

chronology of pleistocene sedimentary cycles in the carmel coastal plain of israel abstract the eastern mediterranean coastal plain of israel is composed mainly of loam and sand and gravel of pleistocene to holocene age supplemented by an upper pleistocene beach rock horizon indicating an alternation of marine coastal and continental environments owing to the complexity of the numerous exposures of aeolianites kurkar and soils hamra in the elongated ridges along the coastal plain it is difficult to set up a reliable stratigraphy a systematic luminescence dating study was carried out on loose sand kurkar and hamra deposits in the coastal plain between netanya and haifa in this study 33 samples were investigated from key sections along the carmel coast the chronological results are in excellent agreement with the geological estimates five periods of sand accumulation and kurkar formation can be distinguished at about 140 130 90 and around 60 ka and between 60 and 50 ka hamra formation took place between 140 and 130 ka around 80 65 and 60 ka and between 20 and 12 ka the beach rock is correlated with the sea level maximum during ois 5e the luminescence dating results indicate that neither kurkar nor hamra formation correlates with glacial and interglacial periods of the northern hemisphere however the chronological succession of these climate related cycles is in good agreement with marine and terrestrial archives in the eastern mediterranean

permian tetrapod extinction events abstract four substantial tetrapod extinctions have been identified during the permian but only one of these is an apparent mass extinction analyses of global compilations of the family level diversity of permian tetrapods have been confounded by incorrect and compiled correlations instead analyzing diversity patterns at the genus level in best sections identifies only one apparent mass extinction of permian tetrapods much evolutionary turnover took place among tetrapods during the latter part of the early permian and had been identified as a single mass extinction at the artinskian kungurian boundary however the only stratigraphically dense tetrapod record of the late early permian from the southwestern usa indicates a succession of extinctions spread out from redtankian through littlecrontonian kungurian time not a single mass extinction olson s gap remains a hiatus in the global record of permian tetrapods equivalent to part of the kungurian roadian across the gap eupelycosaur dominated assemblages were replaced by therapsid dominated assemblages but the claim that this is associated with a mass extinction olson s extinction has been based on compressing all of the extinctions of the redtankian littlecrotonian and olson s gap into one event recognition of olson s gap does not preclude the possibility of an extinction at the early middle permian boundary olson s extinction however the gap in the tetrapod fossil record makes it impossible to establish the magnitude precise timing and structure of the extinctions that took place across olson s gap the only permian mass extinction of tetrapods is the dinocephalian extinction event during the gamkan near the end of the guadalupian which saw the total extinction of dinocephalians and major diversity drop in therocephalians in the karoo basin of south africa this extinction is the loss of at least 64 of generic diversity the changeover from dinocephalian assemblages to assemblages without dinocephalians in other parts of permian pangea suggests that the dinocephalian extinction event was a global event the late permian tetrapod extinctions are older than the end permian marine extinctions furthermore the magnitude of the diversity drop and ecological severity of the end permian tetrapod extinctions have been greatly overstated best sections analysis in the karoo basin indicates a stepwise late permian tetrapod extinction during deposition of the upper dicynodon assemblage zone that took at least 250 000 and perhaps more than a million years the culmination of this stepwise extinction across the highest occurrence of dicynodon boundary of platbergian and lootsbergian land vertebrate faunachrons is a loss of genera not much above an inferred background extinction rate of permian tetrapod genera and resembles the amount of turnover seen at several other boundaries of permian and triassic land vertebrate faunachrons the case for coeval land plant insect and tetrapod extinctions during the permian is a weak one the first coeval marine and nonmarine mass extinctions of the phanerozoic were likely the end guadalupian extinction climate change notably greenhouse climates may have driven permian tetrapod extinctions but that hypothesized relationship needs better documentation

luminescence dating of quaternary sediments recent advances duller geoffrey 2004 luminescence dating of quaternary sediments recent advances journal of quaternary science 19 2 pp 183 192 rae2008

connection between south mediterranean climate and north african atmospheric circulation during the last 50 000 yr bp north atlantic cold events abstract high resolution clay mineralogical analyses were performed on sediment deposited during the last 50 000 yr in the alboran sea odp site 976 the clay mineral record is compared with pollen assemblages and with annual precipitation pann and mean temperatures of the coldest month mtco reconstructed with the modern analog technique mat enhanced contribution of palygorskite a typical wind blown clay mineral characterizes the north atlantic cold climatic events coeval development of the semi arid vegetation artemisia rich associated with a drastic fall of reconstructed precipitations and temperatures suggest cold and arid continental conditions in the west mediterranean area during north atlantic cold events the clay mineral association especially the palygorskite content and the illite to kaolinite ratio indicate western morocco as one of the major source of the clay size fraction during the north atlantic cold events the maximum abundance of artemisia associated with the presence of argania pollen both indicate morocco as the main origin for pollen during these cold periods the comparison of these pollen and clay mineral specific features allows us to pinpoint western morocco as the dominant source of wind blown particles during north atlantic cold events these specific mineralogical composition and palynological assemblages reveal enhanced aridity over north africa and intensification of winds favouring dust erosion and transport from north africa toward the alboran sea during the north atlantic cold events according to atmospheric models such a meridian transport 1 likely results from the development of strong and stable anticyclonic conditions over the tropical atlantic and north africa similar to today s summer meteorological configuration and 2 implies a northward position of the westerly winds during north atlantic cold events finally the synoptic situation over the west mediterranean during the north atlantic cold events is compared with the north atlantic oscillation nao suggesting that during the cold atlantic events weather regimes over europe and north africa may have been systematically shifted towards a positive nao situation

evidence for a diachronous late permian marine crisis from the canadian arctic region a high resolution chemostratigraphic study of a 24 m thick section at west blind fiord on ellesmere island canadian arctic documents stepwise environmental deterioration in the marine sverdrup basin during the late changhsingian late late permian as a result of volcanic disturbances to surrounding landmasses a horizon within the upper lindstrom formation datum a is characterized by increased fe oxyhydroxide fl uxes and weathering intensity as well as modest shifts toward more reducing watermass conditions and higher marine productivity recording an initial disturbance that washed soils into the marine environment the contact between chert of the lindstrom formation and silty shale of the overlying blind fiord formation which is 1 6 m higher and 50 k y younger than datum a records a large increase in detrital sediment fl ux more strongly enhanced marine productivity and a regional extinction of siliceous sponges herein termed the arctic extinction event the horizon equivalent to the latest permian mass extinction of tethyan shallow marine sections is 5 6 m higher and 100 k y younger than the arctic extinction event demonstrating the diachronous nature of the marine biotic and environmental crisis at a global scale it is associated with intensifi ed anoxia and possible changes in phytoplankton community composition in the study section marine environmental deterioration in the sverdrup basin probably triggered by terrestrial ecosystem deterioration and elevated detrital sediment fl uxes was under way by the early part of the late changhsingian well before the onset of main stage siberian traps fl ood basalt volcanism the event sequence at west blind fiord may record the deleterious effects of early stage explosive silicic eruptions that affected the boreal region possibly through deposition of toxic gas and ash within a restricted latitudinal band while having little impact on marine ecosystems in the peri equatorial tethyan region