wintertime winds and coastal sea level fluctuations in the northeast china sea part ii numerical model abstract as a sequel to data analysis reported in part i a numerical model of the wintertime wind driven circulation of the northeast chine sea is developed with the primary purpose of achieving an understanding of the underlying dynamics to several observed features of the coastal sea level behavior the model is linear and pertains to the vertically integrated balance of momentum and mass in a well mixed shallow ocean the model bathymetry incorporates a realistic shelf embayment and an open ocean region of a depth so limited that observed sea level differences across open boundaries in the deep western pacific do not result in unreasonably large model transports from results of model runs for the 1980 81 winter it is found that 1 along the west coast of south korea sea level setup to the south is a consequence chiefly of the presence at the end of the korean peninsula of relatively deep offshore water that is less responsive to wind forcing than the shallow shelf water 2 pressure gradient forc

calibrating the end permian mass extinction the end permian mass extinction was the most severe biodiversity crisis in earth history to better constrain the timing and ultimately the causes of this event we collected a suite of geochronologic isotopic and biostratigraphic data on several well preserved sedimentary sections in south china high precision u pb dating reveals that the extinction peak occurred just before 252 28 0 08 million years ago after a decline of 2 per mil in 13c over 90 000 years and coincided with a 13c excursion of 5 that is estimated to have lasted 20 000 years the extinction interval was less than 200 000 years and synchronous in marine and terrestrial realms associated charcoal rich and soot bearing layers indicate widespread wildfires on land a massive release of thermogenic carbon dioxide and or methane may have caused the catastrophic extinction

recent current observations in the eastern yellow sea observations of current velocity pressure and temperature in the eastern yellow sea from january 10 through april 12 1986 together with geostrophic winds calculated from surface atmospheric pressure distributions are analyzed for a study of the synoptic band response of the yellow sea to the wintertime winds north wind pulses in the winter monsoon are found to give rise to northward flow bursts in the yellow sea trough which appear to peak just as the wind relaxes and to be driven by a synoptic band north to south rise in bottom pressure synchronous with the north wind pulses the existence of a similar rise in coastal sea level indicates that the observed southward pressure rise is but an offshore extension of a setup along the west coast of south korea forced by the north wind pulses the advection by northward flow bursts of warm water from the south apparently causes the measured temperature to be substantially higher in the trough than in coastal waters at the same latitude and the observed rate of cooling in the trough to be less than half of that in coastal waters to the east a winter to spring transition is also found in the bottom pressure records obtained in the trough in which the mean north to south gradient in winter reverses suddenly in early march a similar reversal also appears in sea level records along the west coast of south korea the reversal appears to be triggered by the weakening of the north winds at the arrival of spring

the terrestrial end permian mass extinction in south china abstract the end permian mass extinction reflects the most severe life crisis during the phanerozoic and was associated with major global environmental changes however the consistency of the time and pattern of the terrestrial and marine extinctions remains controversial in this paper we presented detailed analyses of the high resolution biostratigraphical and geochemical data from terrestrial sections in south china our analyses show that the transitional kayitou formation actually recorded the process of terrestrial mass extinction as evidenced by the mass disappearance of the gigantopteris megaflora in the lower part the dramatic reduction in abundance of palynomorphs in the middle and the last occurrences of plant remains and abundant charcoal fossils in the uppermost part it is associated with a distinct negative shift of 13corg beginning in the middle part of the formation which is correlative with that in the top of bed 26 at the marine meishan section in addition the kayitou formation is characterized by a distinct shift of lithofacies of fresh lake swamp or river flat environment from olive grey black mudstone siltstone fine to coarse sandstone in the lower part to gradually increasing maroon rocks to purely maroon mudrocks with poorly sorted breccia calcic palaeosols and calcareous nodules in the lowest part of the dongchuan formation which indicates a dramatic collapse of soil system associated with rapid deforestation and climatic warming and drying in the coastal area the kayitou formation contains marine beds with the typical permian triassic mixed faunas and floras which are correlative with the latest changhsingian marine mixed fauna 1 at meishan the kayitou formation also recorded a distinct transgression that began in the latest changhsingian all above phenomena suggest that the kayitou formation is actually the witness of the terrestrial end permian mass extinction and it is mostly or entirely of latest changhsingian permian rather than triassic age

wintertime winds and coastal sea level fluctuations in the northeast china sea part i observations abstract analyses of low pass filtered coastal sea level data and geostrophic winds derived from surface pressure charts for the period of 1 december 1980 through 31 march 1981 indicate that the wintertime dynamics in the northeast china sea is strongly influenced by the passage of rapidly moving cold fronts from northwest to southeast across the region along the west coast of korea sea level fluctuations are highly coherent with the north south wind in two bands centered respectively at about 0 17 and 0 36 cpd and propagate to the south for the low frequency band removal of the wind forced component of the sea level signal yields freely propagating fluctuations in bands centered at about 0 20 0 34 and 0 50 cpd that travel northward at approximately the phase speed expected for barotropic kelvin waves indicative of a relaxation in the sea level field following the successive passages of cold fronts coherence studies of winds and sea level differences in the tsushima strait indicate a correlation

study of the dynamics of wind driven transports into the yellow sea during winter synoptic wind stresses and surface heat flux force a three dimensional numerical ocean model of the yellow sea east china sea dynamics the basin response to winter winds is examined through the model output fields northerly wind bursts are a frequent winter occurrence in this region the wind bursts develop a southward flowing current along the chinese coast as the wind stress forces fluid out of the bohai sea a north south pressure gradient develops as surface water travels from the bohai sea southward decreasing the elevation in the north relative to the elevation in the south also a westward pressure gradient across the yellow sea basin develops in response to the wind forcing the southward pressure gradient forces a bottom flow in the direction opposite to the wind stress this return flow is concentrated in a deep trough located on the eastern side of the basin after the northerly wind ceases the northward transport increases pressure in the north with the result of slowing or stopping the flow northward at times pressure increases in the north sufficiently to force a southward flow in the trough following strong northerly wind events northward transport into the yellow sea occupies the entire trough and may extend into the northern yellow sea bohai sea during periods of calm winds northward flow usually does not penetrate beyond 34 n in the yellow sea this flow is northward on the western side of the island of cheju the flow turns eastward north of cheju and then southward passing through the cheju korea strait the wind stress along the korean coast often deviates from the northerly wind stress over the rest of the yellow sea thus the flow along the korean coast is not as closely related to the northerly wind bursts as the flow along the chinese coast the winter circulation in the yellow sea is predominately a barotropic response to winds with fluctuations due to ekman flow

sea level variations in relation to coastal flow around the gulf of alaska adjusted sea level deviations at six tide stations around the gulf of alaska were examined in light of our recent knowledge of the flow regime on the east side of the gulf a maximum in the deviations seems to be caused by winter barotropic flow on the shelf on the north side of the gulf the maximum in fall is apparently produced by a marked increase in flow of the baroclinic coastal current farther west the seasonal sea level signal is appreciably reduced

nutrient fluxes via radium isotopes from the coast to offshore and from the seafloor to upper waters after the 2009 spring bloom in the yellow sea abstract the horizontal and vertical transport of nutrient rich water both from the coast and from the seafloor to the overlying water column should play an important role in supplying nutrients required for the periods of vegetative or reproductive growth of phytoplankton in the present work radium isotopes 223ra 224ra and 226ra in the southern yellow sea were measured after a spring bloom in june 2009 the exponential like decrease of 223ra away from the coast to offshore waters yielded horizontal eddy diffusivities kh of 2 93 1 47 107 cm2 s 1 by neglecting the advection this estimate was smaller than that with advection indicator by as much as 21 when using an analytic model for 223ra and 226ra the corresponding horizontal nutrient fluxes were 1525 mol m 2 d 1 din 15 9 mol m 2 d 1 dip and 826 mol m 2 d 1 dsi which would supply around 16 of n and 3 of p requirements based on the primary productivity the decrease of 224ra and 223ra activities from sediments to the upper water column suggests the vertical eddy diffusion coefficient kz of 6 23 5 58 cm2 s 1 below the thermocline which was within the yellow sea cold water mass yscwm the calculated vertical fluxes of nutrient were 4945 mol m 2 d 1 din 236 mol m 2 d 1 dip and 5315 mol m 2 d 1 dsi accounting for up to 52 of n and 40 of p requirements for the phytoplankton growth these results demonstrate the role of yscwm as a relative nutrient rich pool for the supply of nutrient to the southern yellow sea via the vertical diffusion process relative to the horizontal process during the summer season such processes will be strengthened during the weak density stratification in spring when algal blooms occur

extinction patterns among bivalves in south china during the permian triassic crisis abstract late permian changhsingian bivalves in south china are very abundant and diverse in nearshore inner shelf outer shelf and deep basin facies all reported data of both bivalve genera and species from the permian triassic boundary strata of south china have been systematically collected and studied for understanding the evolutionary process of various bivalve groups in different environments through the great permian triassic transition at the genus level bivalves show an extinction rate of 50 in the first phase of the permian triassic crisis though only 9 1 in the second phase there appears to be no selection of extinction in life style feeding type or habitat among bivalves from south china through the crisis there is no significant difference in the extinction rates between epifaunal and infaunal bivalve genera in all environments suspension feeders showed moderate extinction rates while no deposit feeders went extinct at the genus level in addition infaunal bivalves were not at more risk of extinction than epifaunal forms a combination of ocean anoxia and high seawater temperatures might have contributed to the mass extinction among bivalves during the permian triassic crisis

sea surface height variations in the yellow and east china seas 2 ssh variability in the weekly and semiweekly bands two types of models are used to examine the sea surface height ssh variability at the principle short time frequency bands in the yellow and east china seas the models are a primitive equation numerical model and a statistical model based on topex poseidon altimeter data in situ pressure gauge measurements at two mooring locations are first used to evaluate each model in addition a comparison of the numerical and statistical models is made through duplicate analysis of the response to the main extended empirical orthogonal function wind stress modes in the northern yellow sea the wind stress pressure gauge data numerical model and statistical model all indicate local spectral maxima in bands centered on the weekly and semiweekly periods the coherence of the two models with the in situ data is significant down to 3 day periods at the northern mooring and down to 5 day periods at the southern mooring the meridional wind stress variability in the semiweekly band is higher than the weekly band energy in the northern yellow sea and bohai bay and lower than the weekly band energy across the east china sea the ssh variability contained in the weekly and semiweekly bands is largest in the bohai bay and northern yellow sea with a region of high energy along the chinese coast the spatial structure of the weekly and semiweekly ssh variability is similar to the wind stress variability at these bands with semiweekly variability higher in the bohai bay and northern yellow sea and weekly variability dominant in the east china sea

restudy of conodont biostratigraphy of the permian triassic boundary section in zhongzhai southwestern guizhou province south china abstract new conodont samples have been systematically collected at high stratigraphic resolution from the upper part of the longtan formation through to the lower part of the yelang formation at the zhongzhai section southwestern guizhou province south china in an effort to verify the first local occurrence of hindeodus parvus in relation to the permian triassic boundary at this section the resampled conodont fauna from the permian triassic boundary interval comprises five identified species and two undetermined species in hindeodus and clarkina most importantly the first local occurrence of hindeodus parvus is found for the first time from the bottom of bed 28a 18 cm lower than the previously reported first local occurrence of this species at this section considering the previously accepted ptb at the zhongzhai section well calibrated by conodont biostratigraphy geochronology and carbon isotope chemostratigraphy this lower earlier occurrence of h parvus suggests that this critical species could occur below the permian triassic boundary as such this paper provides evidence that 1 the first local occurrences of h parvus are diachronous in different sections with respect to the ptb defined by the first appearance datum fad of this species at its gssp section in meishan china and that 2 the lower stratigraphic range of h parvus should now be extended to latest permian

taxonomic and ecological variations of permian triassic transitional bivalve communities from the littoral clastic facies in southwestern china abstract immediately after the latest permian mass extinction bivalve faunas colonized the permian triassic transitional beds pttb especially in littoral clastic facies of south china the permian triassic p tr transitional bivalve fauna is composed of holdovers long term survivors and newly evolved taxa and characterized by moderate diversity and high dominance however the taxonomy and ecology of this bivalve fauna of littoral clastic facies have not been well understood especially in comparison with offshore marine records this paper presents a study on a p tr transitional bivalve fauna from five sections of littoral clastic facies in southwestern china and as such it contributes to a better knowledge of the ecological processes of benthic communities during the p tr transition in total 20 species in 13 genera of bivalves are identified from the pttb in the lower part of the kayitou formation and the basal part of the feixianguan formation of the five sections cluster analysis suggests that the transitional bivalve fauna could be further divided into two successive communities early and late communities and each is composed of five assemblages promyalina neoschizodus community early community is characterized by presence of holdover taxa high taxonomic diversity and evenness and more abundant shallow infaunal suspension feeders in pteria community late community taxonomic diversity and evenness are much lower and stationary epifaunal suspension feeders boost at the expense of shallow infaunal suspension feeders compared with the promyalina neoschizodus community furthermore the promyalina neoschizodus community shows a clear spatial variation along environmental gradient from brackish lagoon to shallow marine settings while the pteria community is more uniform and homogeneous laterally the promyalina neoschizodus community in the studied region is of latest permian age while the pteria community should belong to the earliest triassic consequently a significant taxonomical and ecological turnover of bivalve communities occurred between the promyalina neoschizodus community and the pteria community during the extinction interval in southwestern china

seasonal circulation patterns of the yellow and east china seas derived from satellite tracked drifter trajectories and hydrographic observations abstract we investigated seasonal circulation patterns of the yellow and east china seas yecs by reviewing previous works on the circulation and its dominant currents and taking into account newly compiled trajectories of satellite tracked drifters collected between the 1980s and 2000s the circulation patterns suggested before the 1990s can be categorized into two groups depending on the identified origin of the tsushima warm current in the korea tsushima straits i branching from the kuroshio southwest of kyushu or ii northeastward continuation of the taiwan strait throughflow the branching of the kuroshio southwest of kyushu and northeast of taiwan was clearly evidenced by current measurements and concurrent hydrographic surveys however there is still no clear evidence for the northeastward pathway of taiwan strait throughflow across the mid shelf area of the east china sea target oriented surveys in the 1990s and 2000s employing advanced instruments such as drifter tracking and acoustic doppler current profiler measurements now provide decisive proof of the clockwise rounding of the cheju warm current around jeju do throughout the year of the northeastward extension of changjiang discharge in summer and of the presence of the yellow sea warm current only in winter thus both coastal currents in shallow water and secondary branch currents of the kuroshio such as the yellow sea warm current are found to significantly change from winter to summer to better present the basic pattern of yecs circulation and its seasonality we have constructed seasonal circulations patterns based on review results on the newly compiled drifter trajectories and on hydrographic observations further investigations should be carried out in future with support of comprehensive current measurements on shelf areas and through elaborate numerical modeling

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

comparison of wind and tidal contributions to seasonal circulation of the yellow sea 1 seasonal circulation of the yellow sea ys in response to wind and tidal forces is examined using a three dimensional numerical model wind forcing affects the wintertime circulation of the ys on the other hand the summer southerly monsoon is weak and therefore has little impact on the circulation on the basis of comparative experiments with and without wind conditions results indicate that the yellow sea warm current yswc along the ys trough exists regardless of wind forcing however strong winter northerly winds intensify the southward coastal flows along both coasts of the ys and therefore the northward intrusion of the yswc becomes stronger these flows in the ys are substantially weakened when wind forcing is not applied to the model in addition to wind driven circulation tide induced circulation is also dominant in the ys particularly in summer in winter the tidal effect weakens the upwind and downwind flows in response to the strong northerly winds while in summer tidal forcing induces a strong southward residual flow along the western slope and a cyclonic gyre with a bottom cold water dome at the central region of the ys the southward residual current possibly explains the southward movement of the yellow sea bottom cold water as observed in summer comparison to the effects of parameterized tidal mixing suggests that residual flow driven by explicit tidal forcing plays an important role in the summertime circulation of the ys

terrestrial paleoenvironment characterization across the permian triassic boundary in south china well preserved marine fossils in carbonate rocks permit detailed studies of the end permian extinction event in the marine realm however the rarity of fossils in terrestrial depositional environments makes it more challenging to attain a satisfactory degree of resolution to describe the biotic turnover on land here we present new sedimentological paleontological and geochemical x ray fluorescence analysis from the study of four terrestrial sections chahe zhejue mide and jiucaichong in western guizhou and eastern yunnan yangtze platform south china to evaluate paleoenvironmental changes through the permian triassic transition our results show major differences in the depositional environments between the permian xuanwei and the triassic kayitou formations with a change from fluvial lacustrine to coastal marine settings this change is associated with a drastic modification of the preservation mode of the fossil plants from large compressions to small comminuted debris plant fossils spanning the permian triassic boundary show the existence of two distinct assemblages in the xuanwei formation a late permian changhsingian assemblage with characteristic cathaysian wetland plants mainly gigantopteris dictyophylloides gigantonoclea guizhouensis g nicotianaefolia g plumosa g hallei lobatannularia heinanensis l cathaysiana l multifolia annularia pingloensis a shirakii paracalamites stenocostatus cordaites sp is identified in the lowermost kayitou formation an early triassic induan annalepis peltaspermum assemblage is shown associated with very rare relictual gigantopterids palynological samples are poor and low yield samples show assemblages almost exclusively represented by spores a similar to 1 m thick zone enriched in putative fungal spores was identified near the top of the xuanwei formation including diverse multicellular forms such as reduviasporonites sp this interval likely corresponds to the ptb fungal spike conventionally associated with land denudation and ecosystem collapse while the floral turnover is evident further studies based on plant diversity would be required in order to assess contribution linked to the end permian mass extinction versus local paleoenvironmental changes associated with the transition between the xuanwei and kayitou formations c 2014 elsevier ltd all rights reserved less

episodic surface intrusions in the yellow sea during relaxation of northerly winds the surface currents over the yellow and east china seas are mapped from the geostationary ocean color imager goci based on a composite of six intrusion events in january april the strong northward surface current in the yellow sea is shown to be concentrated along the deep trough accompanied by a broad northward surface current over the east china sea from the corresponding surface winds the episodic northward surface flow bursts appear to be associated with abrupt changes from the strong northerly winds to weak southerly winds during cold front passages a three dimensional model driven with observed surface winds is used to simulate the observed shelf wide response to northerly winds there is an outstanding agreement between the simulated and observed surface currents the surface intrusion in the yellow sea is shown to be driven primarily by a barotropic longitudinal surface slope while the strong northward current in the east china sea is associated with a coastal trapped wave moreover the surface intrusion is associated with a large volume transport suggesting that the transient intrusions could be important in the northward heat transport the unprecedented capability of goci satellite in providing a regional circulation pattern in conjunction with complementary model simulations could contribute greatly to understanding of the dynamics of the yellow and east china seas

permian bivalve mollusks of northeast asia abstract bivalve mollusks are very important in the permian biota of northeast asia during the permian the bivalves had different distribution patterns both in space and time and their occurrence was governed by many factors related to water depth and geodynamic conditions in northeast asia there were two main bivalve paleocommunities shallow and deep sea bivalves through the permian the bivalves began to dominate benthic assemblages there are five major stages in their developmental history asselian artinskian kungurian roadian wordian capitanian early wuchiapingian and late changhsingian the mid kungurian stage was characterized by a maximum in bivalve diversity whereas the late kungurian early capitanian and latest permian had the lowest bivalve diversity

inertial oscillations in the korea strait inertial oscillations io are examined in the korea strait based on measurements from 13 acoustic doppler current profilers covering the time period may 1999 through march 2000 strong io responses to wind stress occur during summer a simple linear model predicts that winter wind stress is expected to generate inertial responses of the same order of magnitude as those in summer however the observed winter io response is much weaker than predicted during summer the currents within the mixed layer and below the mixed layer are of comparable amplitude but in opposite directions the depth at which the currents reverse directions varies throughout the year as the mixed layer deepens from about 40 m during summer to the bottom of the water column in november during winter the velocity structure is more uniform in depth with currents in the same direction throughout the water column one possible explanation for these phenomena is related to the combined effect of the strait boundaries and the strong summer stratification the stratification prevents the wind stress momentum flux from mixing downward below the thermocline and thus allows the development of a bottom current separate from the surface current such a velocity structure is necessary to satisfy the no flow condition through the land boundaries

mixed continental marine biotas following the permian triassic mass extinction in south and north china abstract correlation between marine and continental permian triassic p tr strata is crucial for full understanding of the nature of this global extinction event but it has proved difficult to achieve here we show that two sections in south china and north china record similar mixed continental marine biota in the post extinction stratigraphic interval including conchostracans plants insects marine bivalves and lingulid brachiopods in addition the continental p tr mass extinction was represented by a sharp decrease in the diversity and abundance of the gigantopteris flora in south china but eliminated the palaeozoic type conifer flora and herbivorous pareiasaurs in north china these mixed continental marine biota provide the biological evidence for stratigraphic correlation between marine and continental p tr transitional beds in south china and north china especially the co occurrence of the pteria towapteria eumorphotis bivalve assemblage and the euestheria gutta bearing conchostracan fauna or euestheria gutta magniestheria mangaliensis palaeolimnadiopsis vilujensis conchostracan assemblage we propose that these specific marine bivalve and continental conchostracan assemblages could be considered as markers of p tr transitional beds in marine continental siliciclastic settings

the end permian regression in south china and its implication on mass extinction abstract records of more than 20 permian triassic boundary ptb sections from south china show that widespread end permian regression took place in whole south china timing of the low ebb of this regression was pinpointed to the clarkina meishanensis and hindeodus changxingensis zones biostratigraphic and paleogeographic studies at conodont zonation level reveal that the yangtze carbonate platform and isolated small carbonate platforms in the hunan guizhou guangxi hgg basin experienced sedimentary hiatus during these two zones which lasted about 50 100 kya meanwhile the basinal areas namely the northern marginal basin of yangtze platform and the hunan guizhou guangxi basin have continuous conodont zonation with silicious and ashbed deposits the basinal areas show two negative 13c shifts during the ptb interval from clarkina yini zone to isarcicella isarcica zone while on the platforms there is usually only one negative shift because the early shift at c meishanensis zone was lost during hiatus the end permian regression and successive rapid transgression taking place at the ptb casted important effects to the pattern and process of the ptb mass extinction the depositional hiatus hitherto underestimated will necessitate reassessment of some interpretations on the causes and results of that extinction

vegetation changeover across the permian triassic boundary in southwest china extinction survival recovery and palaeoclimate a critical review abstract this paper reviews critically the permian triassic p tr fossil plants and microflora recorded in three well studied terrestrial permian triassic boundary ptb sections namely chahe zhejue and jiucaichong and two marine terrestrial transitional ptb sections namely mide and tucheng in western guizhou province and eastern yunnan province wgey southwest china distinct floral composition abundance and diversity across the ptb allow the establishment of two terrestrial macrofloral assemblages the lobatannularia multifolia gigantoclea guiyangensis l g assemblage was recognized from the upper xuanwei formation while the annalepis peltaspermum a p assemblage from the lower kayitou formation the former flora comprises 105 species in 39 genera and is late changhsingian in age the latter assemblage includes 18 species in 14 genera and is induan in age the changhsingian assemblage is characterized by the loss of many wuchiapingian elements of the gigantopteris flora and an increase of the gymnosperms most of the permian type plant taxa were wiped out in the ptb crisis on land with only few relicts persisting into the early triassic which saw the flourishing of annalepis and common presence of peltaspermum and permian relicts of the gigantopterids during the permian triassic transition some rare gigantopterids elements as well as some peltaspermum representatives survived the biocrisis annalepis a pioneering lycopsid genus in the recovery of the triassic land plants and its proliferation marks the recovery of land plants after the ptb crisis on land in wgey accordingly vegetation changeover across the ptb is marked by a dramatic turnover of plants on land from the permian gigantopteris flora to the triassic annalepis dominated assemblage palynofloras are characterized by a dramatic drop of palynomorphs in both abundance and diversity and show a stepwise extinction pattern moreover macro and microfloras of the wgey region indicate that humid and warm climate regime prevailed through the p tr transition in southwest china the coal forming swamps gradually migrated westward due to marine transgressions throughout the late permian the gigantopteris flora also migrated from east to west and a few species can survive into the earliest triassic in the wgey region but disappeared soon after

the late miocene paleoenvironment of afghanistan as inferred from dental microwear in artiodactyls abstract dental microwear of late miocene artiodactyls from afghanistan can yield information on paleodiet and thus inferences can be drawn about their paleoenvironment the molayan locality lies at the border between the greek iranian and siwalik bioprovinces knowledge of the paleoenvironment will further our understanding of the faunal exchanges between these two provinces during the late miocene ninety nine specimens of seven bovid and one giraffid species are considered the number and diversity of the samples provide objective data which enable the reconstruction of the paleoenvironment prostrepsiceros aff vinayaki and sporadotragus tadzhikistanicus have similar dental microwear pattern which suggests a meal by meal mixed feeding diet phronetragus aff secondus gazella sp and the giraffid palaeotragus cf rouenii can only be characterized as mixed feeders in a general sense dorcadoxa porrecticornis was an obligate grazer and the two species of tragoportax were variable grazers the analysis also brings out clear similarities between extinct grazers and equus przewalskii which is a c3 grazer isotopic evidence from previous studies supports the microwear data comparisons with data from the late miocene of the potwar plateau suggest strong environmental differences with the afghan locality when brought together this disparate evidence about diet suggests an open and dry environment composed mainly of c3 grasses and evergreen bushes during the late miocene in afghanistan

survival patterns of macrobenthic marine assemblages during the end permian mass extinction in the western tethys dolomites italy abstract the ecological competition between brachiopods and bivalves is analysed by means of a quantitative palaeoecologic method applied on four assemblages located within a short stratigraphic interval approximately 2 m thick in the lower tesero member of the werfen formation in the southern alps the assemblages originate from the tesero bulla and sass de putia sections the analysed stratigraphic interval uppermost changhsingian in age is located between the early and heaviest phase of the end permian mass extinction which occurred across the bellerophon werfen formational boundary event boundary and the permian triassic boundary chronological boundary when nearly all the permian stenotopic holdovers disappeared these assemblages are characterised by small sized skeletons lilliput effect which represent an adaptive survival strategy in stressed and harsh habitats resulting from the climatic and palaeoceanographic changes connected with the mass extinction the tesero assemblages are dominated by rhynchonelliform brachiopod orbicoelia bed cnt10 or streptorhynchus bed cnt11a which were mostly attached at the top of shallow microbialitic mounds these assemblages are again dominated by permian stenotopic taxa and show a palaeozoic structure the tesero habitat which again permitted the survival of brachiopods represented one of the last refuges in the western tethys on the contrary the bulla bu9 10 and sass de putia wpk13a assemblages are bivalve dominated and thus show an ecologic structure typical of early triassic post extinction marine benthic communities or palaeozoic stressed marine communities the bivalve dominated assemblages proliferated in prevailing muddy siliciclastic substrates with brief episodes of microbial algal growth the most important environmental limiting factors and leading causes of end permian mass extinction are discussed in terms of palaeoautecologic and palaeosynecologic analysis the different taxonomic composition and ecologic structure of the assemblages is related to palaeogeography including water depth and connections with the open sea the brachiopod dominated assemblage exclusive of the tesero section proliferated in microbial carbonate habitats in near shore environments the bivalve dominated assemblages which were more widespread than the brachiopod assemblages in the dolomites and also occurred in other western tethys localities occur in more open and deeper marine environments in the western tethys margins the local distribution of mixed faunas suggests that the extinction of permian stenotopic taxa was caused by the onset of poisonous water on the shelves originating from deep marine environments this extinction pattern appears to be a regional phenomenon and does not seem be applicable on a global scale the extinction events were controlled by a complex network of interactive factors and the survival of faunal elements was probably stochastic

two pulses of extinction during the permian triassic crisis over 90 of marine species were lost during the end permian extinction fossil data show that the crisis in china was marked by two distinct phases of marine extinction separated by a 180 000 year recovery period

holocene paleoenvironmental changes in mud area southwest off cheju island east china sea evidence from benthic foraminiferal assemblages and stable isotope records abstract a sediment core retrieved from the mud area southwest off cheju island masci was analysed for benthic foraminifera grain size and stable isotopes and constrained by ams14c dating holocene paleoenvironmental changes in this broad shallow shelf were investigated with special focus on the evolution of the masci and its related ocean eddy system the results indicate that the east china sea shelf has undergone four major environmental evolution stages during the holocene prior to 9 8 cal kyr bp the benthic foraminiferal assemblages were dominated by low salinity shallow water species ammonia beccarii linnaeus elphidium advenum cushman and cribrononion subincertum asano reflecting a near coast deposit environment a noticeable transition of the benthic foraminifera from an a beccarii dominated to ammonia compressiuscula brady dominated assemblage taking place at approximately 9 8 cal kyr bp together with a contemporaneous increase in 18o and 13c provides evidence that a rapid rise in sea level occurred at this time in the east china shelf a gradual increase in 18o between 9 8 and 6 cal kyr bp indicates a steady strengthening influence of open ocean water on the area under study a sudden increase in the abundance of benthic foraminifera along with a decrease in the coarse fraction imply that an early eddy circulation system was established since almost 6 cal kyr bp in the masci this eddy circulation system was quite weak but gradually strengthened between 6 and 3 cal kyr bp possibly due to the intrusion of the yellow sea warm current yswc a more stable mud deposition period characterised by a high sedimentation rate of fine grained sediment and lighter value of 13c starting at approximately 3 cal kyr bp indicates that the masci was formed mainly during the late holocene we believe that the strengthened yswc since 3 cal kyr bp might increase the trap efficiency of the eddy system thereby accounting for the high sedimentation rate of mud deposits during this period

permian marine paleoecology and its implications for large scale decoupling of brachiopod and bivalve abundance and diversity during the lopingian late permian abstract the transition during the permian triassic interval from brachiopod rich benthic marine assemblages to communities with diverse molluscs has been well constrained by measures of global taxonomic richness but its ecological context has not been studied using quantitative relative abundance data new relative abundance data from early middle and late permian silicified fossil assemblages from offshore shelf carbonate environments indicate that molluscs increased significantly in relative abundance from 0 8 in the middle permian guadalupian to 65 4 in the late permian lopingian these numerical changes are accompanied by increases in the abundance of infaunal bivalves and motile gastropods in the late permian although this ecological change was coincident with the end guadalupian extinction a new global diversity compilation indicates that the overall genus level severity of that biotic crisis was substantially lower than previous estimates the pronounced ecological shift was instead concurrent with the onset of deep marine anoxic or euxinic conditions around the guadalupian lopingian boundary suggesting that increased environmental variability in proximity to the deep water mass may have given eurytopic molluscs a competitive advantage over more stenotopic brachiopods however the lack of global changes in relative genus richness implies dramatic decoupling of global taxonomic and local ecological processes the pronounced increase in molluscan abundance and alpha diversity in the silicified assemblages contrasts with their unchanged global taxonomic richness and may also have resulted from increased environmental stress in offshore shelf environments these results demonstrate that the ecological transition from the brachiopods to molluscs was more complex than inferred from global measures of taxonomic richness and imply that initial stages of permo triassic environmental deterioration may have been responsible for the decoupling of local ecological from global taxonomic processes during the dramatic late permian rise of the modern fauna

effects of the yellow sea warm current on the winter temperature distribution in a numerical model 1 the temperature distribution and circulation patterns in the yellow sea ys are examined by using a wave tide circulation coupled numerical model this model sufficiently reproduces the variation of the warm tongue structure of the yellow sea warm current yswc from the double branches flowing along the ys trough and the western 60 m isobath in january to the single stream along the western temperature front in march this is observed in both the long term monthly climatology and the satellite based sea surface temperature images in recent years examining the local heat balance in the numerical model during the entire cooling period it is found that the yswc has a very important influence on the ys warm tongue structure compared with the surface cooling the influence of the advection is small in the coastal shallow area but large in the deep warm tongue area up to 50 of the magnitude of heat flux although bathymetry is the essential factor which causes the temperature front the yswc is the key factor which positions shapes and maintains the warm tongue structure this helps to affirm the existence of the yswc at least as a monthly mean flow however more high resolution current observations in deeper layers west of cheju island and the western fork of the ys trough are needed to confirm the existence of the yswc and its characteristic timescale in the real ys

aftermath of the permian triassic mass extinction event paleoecology of lower triassic carbonates in the western usa paleoecologic study of invertebrate faunas from three successive early triassic seaways reveals that biotic recovery from the end permian mass extinction event was slow and that full recovery did not occur until after the early triassic simple cosmopolitan opportunistic generalists and low diversity low complexity paleocommunities were characteristic of the entire early triassic in the western usa an increase in guild and taxonomic diversity was observed with the addition of several new higher taxa in the late early triassic spathian to the almost exclusively molluscan faunas of the earlier early triassic nammalian potential disaster forms the inarticulate brachiopod lingula and the paper pecten claraia dominated the earliest early triassic faunas griesbachian and even occurred in the late early triassic normal marine stromatolites comparison with data on faunas from the permian and triassic suggests that even the most diverse early triassic faunas in the spathian were rather low in guild diversity and species richness these characteristics of genera and paleocommunities in the early triassic may be typical of mass extinction aftermaths