the tindouf basin a marine refuge during the serpukhovian carboniferous mass extinction in the northwestern gondwana platform abstract several macrofaunas and microfossils of the carboniferous saharan basins have longer stratigraphic ranges than those of other basins in the western palaeotethys realm particularly in the tindouf basin morocco algeria foraminifers are particularly abundant and diverse in the serpukhovian and basal bashkirian compared to coeval basins and some taxa have longer ranges than in the neighbouring reggan and bechar basins although this effect is more marked compared to the western palaeotethyan assemblages in europe several rugose coral species are recorded from the early bashkirian that previously were considered to have disappeared in the serpukhovian the tindouf basin as one of the most western saharan basins in north africa shows the greatest stratigraphic ranges of taxa which diminish eastwards evidence for a mass extinction event during the serpukhovian in the tindouf basin has not been clearly recognized although a possible influence of glaciation is observed in the faunal diversity eustatic sea level changes were experienced in tindouf with the cyclic pattern of sedimentation but warm water ocean currents from the palaeoequator were able to maintain tropical conditions on the platform tectonics in the area led to emerging land masses and barriers and created a partly isolated basin in this sector of the western part of the sahara platform in northern gondwana the combination of those factors controlled the environmental conditions in the area allowing the persistence of the fauna for longer stratigraphic ranges than its equivalent counterparts in the western palaeotethys

proglacial deposition and deformation in the upper carboniferous to lower permian wynyard formation tasmania a process analysis abstract the wynyard formation of tasmania australia provides the youngest evidence of grounded ice during the late carboniferous early permian in the tasmania basin of southeastern gondwana during the late paleozoic ice age within the wynyard formation four facies associations are recognized 1 massive diamictite 2 stratified diamictite 3 conglomerate and sandstone and 4 deformed mudstone and fine sandstone a detailed facies analysis was performed in order to interpret the depositional processes and environments the massive diamictite facies association contains massive diamictite and sandstone and was deposited primarily by iceberg rain out in a subaqueous morainal bank setting the stratified diamictite facies association is composed of stratified diamictite sandstone and conglomerate and was deposited by debris flows and iceberg rain out and deformed by glacial pushing the conglomerate and sandstone facies association is made up of cross stratified channelized conglomerate and pebbly sandstone that were deposited by glacial outwash on grounding line fans the deformed mudstone and fine sandstone facies association is composed of pervasively deformed pebbly mudstone and fine grained sandstone that exhibit volcano flame and dyke structures this facies association was deposited by a combination of suspension settling iceberg rain out and soft sediment deformation in a quiet distal proglacial setting the facies analysis supports the interpretation that the wynyard formation was deposited by a wet based tidewater glacier or glaciers the depositing glacier s occupied a 40 km wide trough in northwest tasmania based on the distribution of the wynyard formation and the presence of glacial deposits in other eroded troughs in tasmania glaciation occurred in the region within broadly eroded valleys the wynyard formation and overlying mudstone of the inglis formation provide a glacial postglacial signature similar to those in south africa antarctica and eastern australia during the latest carboniferous early permian therefore the climate warmed in southern gondwana following this glacial interval the continued glaciation in eastern australia was a result of regional topography and oceanographic processes

isogramma meek and worthen 1870 dictyonellida brachiopoda from the upper palaeozoic of east asia implications for biogeography and evolutionary trends abstract isogramma manchoukuoensis from the upper carboniferous of northeast china is redefined based on re examination of the type specimens isogramma specimens from the middle permian of northeastern japan are reassigned to i aff paotechowensis a new family schizopleuroniidae is proposed to include schizopleuronia but excludes megapleuronia which belongs to the megapleuroniidae liao 1983 the family isogrammidae is considered to be a transitional group in the eichwaldid isogrammid schizopleuronid evolutionary lineage within the dictyonellida a review of the global distribution of isogramma species reveals that the genus has a total of 56 species ranging from the mississippian early carboniferous to the lopingian late permian isogramma diversified rapidly after its origination in the middle visean and its species diversity remained high throughout the mississippian the genus possibly suffered a severe mid carboniferous boundary mass extinction with no early carboniferous species surviving this event bashkirian isogramma species show low diversity followed by a global recovery in the moscovian during the latest carboniferous isogramma became highly diversified again at the carboniferous permian c p transition isogramma underwent another dramatic diversity drop followed by several stepwise declines in diversity during the early middle permian the wuchiapingian i sinosa is the last isogramma species ukraine was the possible centre of origin for isogramma from ukraine isogramma spread over the moscow basin of russia central europe germany austria south europe spain and west europe england ireland and scotland and migrated to the north american midcontinent and south china during the late visean early carboniferous in europe isogramma migrated to spain and eastern europe serbia in the moscovian from there it then dispersed into central asia uzbekistan and kazakhstan in the kasimovian gzhelian in the palaeo tethys isogramma migrated from south china to northeast and northwest china in the moscovian spread over the north china block during the c p transition moved to russian siberia japan and the qiangtang terrane of the palaeo tethys during the early late permian in north america isogramma spread over the midcontinent during the late carboniferous and early middle permian and migrated to south america bolivia in latest carboniferous biogeographically isogramma was confined principally to the palaeo tropical and warm to temperate zones throughout the late palaeozoic with the possible exception of the artinskian as a questionable species of the genus also occurs in the transbaikal region of southeast russia

onset of late palaeozoic glacio eustasy and the evolving climates of low latitude areas a synthesis of current understanding studies of depth sensitive carbonate successions in the uk indicate that regular orbitally forced glacio eustatic sea level oscillations which characterized the late palaeozoic started abruptly around 330 ma early asbian the gondwanan ice sheet was highly sensitive to orbitally forced variations in solar insolation and the resultant sea level oscillations had an approximate 100 ka periodicity studies of fossil soils and palaeokarst from low latitude settings suggest that pre asbian climates were relatively stable with infrequent changes however climatic changes became increasingly frequent in the asbian and brigantian with regular fluctuations of a sub 100 ka periodicity occurring during glacial lowstand intervals

immigration and extirpation selectivity patterns of brachiopods and bivalves across a carboniferous glacial to non glacial transition pennsylvanian central western argentina and their influence in building the biotic bathymetric gradient abstract the growth and demise of glaciers during the late paleozoic ice age had profound consequences on the marine biota in central western argentina the transition from glacial to non glacial interval during the pennsylvanian caused a major regional turnover which remodeled the bathymetric diversity gradient in order to understand the nature of the environmental changes related to such turnover event we compared selectivity patterns in extirpation and immigration of bivalves and brachiopods using logistic regression we tested for a wide range of potential drivers of extirpation and immigration namely body size geographic range size environmental breadth preferred depth metabolic rates infaunalism and taxonomic identity while extirpation preferentially hit brachiopods and genera having smaller geographic ranges and smaller body sizes immigration was related to genera with preference for deeper environment and small geographic ranges extirpation selectivity was not uniform along the bathymetric gradient both geographic range and body size selectivity are stronger towards deeper environments each clade on the other hand showed idiosyncratic responses to climate change while brachiopods show extirpation selectivity for smaller geographic ranges small sized bivalves were preferentially extirpated these contrasting selectivity regimes however could be reflecting different faunal responses to the same environmental changing factor namely higher thermal amplitude immigration in both brachiopods and bivalves was related to preference to deep environments confirming previous results however brachiopods also showed preferential immigration of small geographic range genera which is puzzling given the extinction selectivity related to the glacial non glacial transition possible explanations point to a brief time span in which an increase in thermal amplitude occurred the rapid climate changes particularly related to a rise in maximum temperatures lead the ecological response of the benthic faunas differences in extinction and immigration selectivity along the bathymetric gradient suggest that the turnover event also remodeled the bathymetric gradient in body size and biogeographic structure and brachiopod bivalve proportions such changes were driven by extirpation contrasting with the remodeling of the bathymetric diversity gradient that was driven by immigration our results therefore highlight that immigration and extirpation can shape different aspects of the bathymetric biotic gradient

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

astronomical cycles in the serpukhovian moscovian carboniferous marine sequence south china and their implications for geochronology and icehouse dynamics abstract the late paleozoic ice age ca 335 260 ma lpia has long been considered as an analogy for the cenozoic ice age since the oligocene the impact of astronomical forcing on the lpia glaciation has been hampered due to the low resolution multi million year scale time framework in the present study high resolution cyclostratigraphy based on magnetic susceptibility ms covering the serpukhovian to late moscovian icehouse climate has been investigated in the luokun section of south china power spectral analysis of the ms series reveals 3 44 4 m 0 8 1 07 m 0 3 0 32 m and 0 17 0 19 m thick sedimentary cycles based on the available biostratigraphic constraints calibrating the 3 44 4 m cycles to the 405 kyr eccentricity cycles indicates short eccentricity 136 and 100 kyr short obliquity 34 kyr and precession 19 and 15 9 kyr orbital bands in addition to long eccentricity 405 kyr band we assigned the basal serpukhovian and moscovian stages in luokun with the numerical ages from geological time scale 2012 to construct two floating time scales ranging from 331 55 0 5 ma to 323 2 0 5 ma and from 315 34 0 35 ma to 310 17 0 35 ma respectively the modulation of main obliquity s4 s3 term has a main periodicity of 1200 kyr the modulation of 100 kyr eccentricity g4 g3 term shows a main periodicity of 2400 kyr with subordinate periodicities of 1620 and 1200 kyr for the serpukhovian and a main periodicity of 1600 kyr for the moscovian they may provide the geological evidence for a chaotic resonance associated with interactions between the orbits of mars and the earth in the carboniferous a duration of 7 68 0 15 myr was estimated for the serpukhovian stage eight higher accumulation rate events due to glacioeustatic drawdown were temporally constrained and show close correspondence to far field and near field reconstructions of the lpia glaciation glacioeustasy was paced with 405 kyr long eccentricity and 1 2 myr obliquity amplitude cycles during the serpukhovian and moscovian stages likely indicating the nature in the warmer icehouse world similar to that of the oligocene to pliocene

west greenland and global in situ 14c production rate calibrations the in situ cosmogenic nuclide 14 c is unique compared with other nuclides because of its short half life and when combined with longer lived isotopes e g 10 be in situ 14 c can be a powerful tool for deciphering recent and complex surface exposure histories like all in situ cosmogenic nuclides quantifying earth surface processes with in situ 14 c requires a well constrained in situ 14 c production rate we present a production rate calibration from an independently dated moraine in west greenland previously used as an in situ 10 be production rate calibration site the local in situ 14 c production rate is 22 8 1 4 atoms g 1 a 1 69 28un 50 76u w 350m asl and when scaled to sea level high latitude using time dependent lal stone scaling lm we calculate a spallation only in situ 14 c production rate of 12 0 0 9 atoms g 1 a 1 and a 14 c 10 be production rate ratio of 3 1 0 2 the west greenland in situ 14 c production rate is indistinguishable from the new zealand promontory point and scottish highlands in situ 14 c production rates when combined we calculate a global production rate of 12 1 0 5 atoms g 1 a 1 lm copyright 2014 john wiley sons ltd

rapid onset of late paleozoic glaciation on gondwana evidence from upper mississippian strata of the midcontinent united states direct evidence of the late paleozoic glaciation of gondwana from glacial deposits suggests that geographically extensive continental glaciation began some time in the namurian late mississippian however the timing and characteristics of the onset of glaciation are poorly understood because of a lack of reliable paleontological control and reworking of initial glacial deposits by subsequent glacial advances indirect evidence of glaciation preserved in unconformity bounded low latitude ramp sequences in the illinois basin united states suggests that geographically extensive continental glaciation of gondwana actually began in the late visean an abrupt change from carbonate dominated sequences bounded by disconformities with little evidence of erosion to mixed carbonate siliciclastic sequences bounded by unconformities with deep incised valleys was likely produced by a three fold increase in the magnitude of eustatic sea level fluctuations the increase in the magnitude of sea level fluctuations was likely driven by an equally abrupt increase in ice volume and marks the onset of the geographically extensive late paleozoic glaciation of gondwana a possible explanation for the rapid onset of glaciation is the closing of the equatorial seaway between laurussia and gondwana closing of this seaway would have led to an abrupt change in oceanic and atmospheric circulation patterns that could have initiated major continental glaciation in the southern hemisphere

global events of the late paleozoic early devonian to middle permian a review abstract the late paleozoic early devonian to middle permian was an interval of profound changes in earth surface systems reflected in dynamic interplay among the biosphere hydrosphere atmosphere and geosphere major events transpired including the colonization of landmasses by vascular plants the assembly of the supercontinent pangea two first order mass extinctions the frasnian famennian and devonian carboniferous boundary events and the most severe icehouse climate mode of the phanerozoic the late paleozoic ice age lpia the goals of the present review are 1 to summarize major global developments in climate oceanography and paleobiology during the late paleozoic 2 to examine the roles of land plant evolution global tectonics and large igneous province magmatism in driving these developments and 3 to serve as an introduction to the 23 contributions to this special issue of palaeogeography palaeoclimatology palaeoecology indicating how they advance our knowledge of various scientific issues related to these developments

bathymetric and isotopic evidence for a short lived late ordovician glaciation in a greenhouse period the end ordovician glaciation is distinct among phanerozoic glaciations in that co 2 levels were generally high yet major continental ice sheets accumulated on the gondwana supercontinent new oxygen isotopic data indicate substantial changes in sea water temperatures and ice volume coinciding with glacio eustatic changes in sea level reflecting the growth and decay of the gondwana ice cap major glaciation was apparently confined to the hirnantian and was 0 5 1 m y long rather than the 35 m y of earlier estimates carbon isotope values indicate significant changes in carbon cycling as the oceans changed from a state with warm saline bottom waters to a state with cold deep water circulation and then back again we believe that the changes in the carbon cycle effected a reduction in p co 2 levels in the oceans and atmosphere and thus promoted glaciation but were unable to sustain icehouse conditions in a greenhouse world

permian diamictites in northeastern asia their significance concerning the bipolarity of the late paleozoic ice age despite a lack of detailed sedimentologic analyses diamictites in the middle permian atkan formation were previously interpreted as glaciomarine and glacially influenced marine deposits this interpretation allowed this unit to play a prominent role in paleoclimatic and biogeographical reconstructions associated with presumed bipolar glaciation during the late paleozoic ice age lpia in this sense the lpia is considered to be a close analog to bipolar glaciation and climate change during the cenozoic here results are presented that challenge the glacigenic interpretation for these strata and negate interpretations of the bipolar nature of the lpia the 400 to 1500 m thick atkan formation was deposited in back arc basins associated with activity of the okhotsk taigonos volcanic arc along the leading edge of pangea as it drifted across the north polar circle the occurrence of tuffs volcanic clasts and glass shards indicate derivation from a nearby arc cooling and solidification of some clasts during sedimentation is suggested by the occurrence of clasts with embayments and protrusions that extend into the surrounding matrix clasts with columnar like jointing and alteration of the matrix surrounding some clasts ca tims dating of tuff zircons indicate a late capitanian age which is consistent with fossils within the strata bedded diamictites deposited as debrites dominate these diamictites which occur as tens of m thick downlapping packages that thicken then thin upward were deposited as prograding and abandoning sediment gravity flow fans chaotic and folded strata formed as slumps graded sandstones and conglomerates were deposited as turbidites and mudstones were deposited as mudflows low density turbidites and hemipelagic deposits striated clasts and outsized clasts piercing bedding were not observed in the study area strata above and below the atkan formation contain abundant graded beds and deep water trace fossils indicating deposition as turbidites the combination of debrites turbidites slumps volcanic grains clasts glass and tuffs and an absence of glacigenic indicators suggest that atkan strata were deposited in deep water basins associated with the development of the volcanic arc rather than due to glacial activity these findings are significant as they require reconsideration of current views of lpia glaciation and suggest that ice sheets were limited to gondwana

phanerozoic large igneous provinces lips heatt haline euxinic acidic thermal transgression episodes and mass extinctions abstract the phanerozoic consists of three mutually exclusive climate states icehouse greenhouse and hothouse the greenhouse is the default state representing 70 of the phanerozoic it is characterized by a weak thermal mode pole driven deep water formation with little or no continental sea ice and weakly oxic cool water sinking near the poles nitrogen limitation characterizes greenhouse oceans in which ammonium may be the dominant bioavailable form of nitrogen the steady state greenhouse default must be forced to produce either of the other two states continent continent collision produces the intense chemical weathering that draws down atmospheric co2 and results in the icehouse state that comprises 20 25 of the phanerozoic icehouses have ice caps in contact with the ocean that produce icebergs and foster sea ice formation sea ice formation fills the ocean with highly oxic phosphorus limited icewater except for a thin layer of warm surface water in the tropics of the 23 most conspicuous mass extinctions of the phanerozoic including the late ediacaran 4 are associated with ice volume related regressions and 3 are problematic we suggest that the other 16 mass extinctions occurred when greenhouse climate was forced to hothouse climate large igneous provinces lips can trigger the heatt haline euxinic acidic thermal transgression mechanism which can force greenhouse climate to a hothouse climate state the rapid voluminous co2 emissions of lips cause a series of events that result in very slow but pronounced haline mode circulation mid latitude driven deep water formation that produces warm saline bottom water at very dry hot subtropical and middle latitudes this water upwells at the poles causing warm and moist equable climate hothouse development promotes deep sea anoxia that is generated in concert with co2 buildup and warming the spread of anoxia favors reduced nitrogen over nitrate and limited iron dust curtails nitrogen fixation this leads to dominance of primary productivity by primitive green algae and or cyanobacteria progression to euxinia that reaches the photic zone severely curtails primary productivity via poisoning even as availability of usable nitrogen plummets the result is eukaryotic mass extinction we suggest that the 16 phanerozoic mass extinctions referred to above resulted at least in part from the heatt process evidence for this relationship at 11 of the most severe extinctions is convincing data sets for the other 5 are strongly suggestive of heatt related mass extinction but do not yet have enough documentation to reliably characterize them as heatt episodes

ecological ranking of phanerozoic biodiversity crises the serpukhovian early carboniferous crisis had a greater ecological impact than the end ordovician we propose a new ecological ranking of the major phanerozoic biodiversity crises in which the serpukhovian biodiversity crisis is ranked fifth in ecological impact lesser than the late devonian but greater than the end ordovician and the end ordovician mass extinction is ranked sixth it is interesting that both the end ordovician mass extinction and the serpukhovian biodiversity crisis were triggered by glaciations other than that common trigger the two events were very different glaciation in the ordovician triggered an enormous jump in the extinction rate of marine organisms and was taxonomically very severe yet the ecological impact of those extinctions was minimal glaciation in the serpukhovian triggered a precipitous drop in the speciation rate but only moderate diversity losses yet the ecological impact of those diversity losses and ecosystem restructuring was an ecological level of magnitude larger than that seen in the end ordovician mass extinction

determinants of extinction in the fossil record the causes of mass extinctions and the nature of biological selectivity at extinction events are central questions in palaeobiology it has long been recognized however that the amount of sedimentary rock available for sampling may bias perceptions of biodiversity1 2 3 4 5 6 7 and estimates of taxonomic rates of evolution5 6 7 8 this problem has been particularly noted with respect to the principal mass extinctions5 6 7 8 9 10 11 12 here we use a new compilation of the amount of exposed marine sedimentary rock to predict how the observed fossil record of extinction would appear if the time series of true extinction rates were in fact smooth many features of the highly variable record of apparent extinction rates within marine animals can be predicted on the basis of temporal variation in the amount of exposed rock although this result is consistent with the possibility that a common geological cause determines both true extinction rates and the amount of exposed rock it also supports the hypothesis that much of the observed short term volatility in extinction rates is an artefact of variability in the stratigraphic record

carbonate collapse and the late paleozoic ice age marine biodiversity crisis el set de datos contiente datos de la paleobiology database paleobbd org cruzados con los datos de macrostrat macrostrat org datos crudos de macrostrat y los scripts necesarios para reproducir el trabajo

problems of a late palaeozoic glaciation in australia and subsequent climate in the permian the most recent information suggests two periods of glaciation separated by a considerable time interval the first is found in the namurian early carboniferous and may extend into the beginning of the late carboniferous evidence for the carboniferous glaciation is largely or entirely redeposited striated clasts known only from the new england area of northeastern new south wales these are considered to represent montane type glaciation associated with a developing alpine chain after a long interval glacial deposits are then found in many parts of australia in the asselian the lowest stage of the permian and the glaciation may extend into the beginning of the sakmarian the following stage in western australia a number of major fluctuations are recorded in the asselian the end of the glaciation seems to be associated with a worldwide eustatic rise in sea level in the tastubian the lower stage of the sakmarian after the tastubian no direct verifiable evidence indicates glaciation in the permian in australia or any other part of the world in australia there is no clear evidence on the climate in the interval between the two glacial periods but in south america and other parts of the world a warm interval is reported at this time most of the glacial debris is now found in sedimentary basins which were developing contemporaneously with the glaciation and is of a wet based type glaciers were active on steep hinterland carrying debris in adjacent water covered basins but how far the ice may have spread over lower lying land areas in not clear there is no real evidence of a thick dry based ice sheet like that of present antarctica after the tastubian there are a number of major fluctuations in climate during the rest of the permian at times seasonal ice and or perhaps icebergs may have been active but fluctuations which were cool or warm temperate or in some places in australia even subtropical or tropical are found in the sterlitamakian upper sakmarian beginning and end of the baighenzhinian upper artinskian kungurian kazanian and dzhulfian all separated probably by colder and in some cases considerably colder periods comparison of the marine faunas of the carboniferous and permian suggests that the levipustula fauna may not represent as cold sea water as the eurydesma fauna

depressed rates of origination and extinction during the late paleozoic ice age a new state for the global marine ecosystem rates of origination and extinction for marine animal genera dropped to low levels in latest mississippian time immediately after massive glaciers formed in the southern hemisphere and a second order mass extinction occurred evolutionary turnover and diversity remained low for 50 m y shifting markedly upward precisely when extensive glaciation ended in early permian time all diverse taxa with good fossil records experienced low rates of origination and extinction during this major ice age such sluggish rates would be predicted for faunas of shallow seas on or adjacent to a heavily glaciated supercontinent such as pangea where cool and highly seasonal thermal regimes should dictate that species have broad ecological niches widespread geographic distributions and large and relatively stable populations

comparison of taxonomic diversity strontium isotope and sea level patterns sepkoski s compendium of 28 730 marine genera was analyzed with a view toward comparing taxonomic diversity strontium isotope stratigraphy and sea level changes the fossil record analyses discriminated between origination extinction and pass through genera and collectively delineated changes in number of genera with time at the largely stratigraphic stage level with notable exceptions of the cretaceous and tertiary taxonomic diversity generally paralleled both strontium isotope stratigraphy and sea level changes sampling bias was suggested in the tertiary where an increase in genera numbers toward the recent opposed the downward trends of both strontium isotope and sea level curves the removal of all recent genera from the sepkoski database confirmed the bias in producing complimentary downward trends in all curves regression analysis of taxonomic diversity with respect to sea level extent and time duration explained 82 of the variability of the remaining data sea level fluctuations are not always accompanied by significant changes in taxonomic diversity but strontium isotope analyses offers the potential of constraining the extent to which the magnitude of changes are associated with time duration

climatic basis for sluggish macroevolution during the late paleozoic ice age rates of origination and extinction for marine invertebrates fell at the onset of the late paleozoic ice age in late mississippian time and remained low until glaciation ended in middle permian time through the use of a database of stratigraphic and geographic occurrences of brachiopod genera these macroevolutionary changes are traced to the loss of genera with narrow latitudinal ranges which had intrinsically high turnover rates at the onset of glaciation in late visean time when glaciation waned in late sakmarian time narrowly distributed genera rebounded abruptly and restored the global fauna to its pre ice age configuration because narrowly distributed brachiopod genera had dominated tropical diversity the major biotic effects of the late paleozoic ice age were felt at low latitudes the climatic regime of this ice age thus altered the marine ecosystem to one characterized by broadly adapted long lived genera

a new model for atmospheric oxygen over phanerozoic time a mathematical model has been constructed that enables calculation of the level of atmospheric o2 over the past 570 my from rates of burial and weathering of organic carbon c and pyrite sulfur s burial rates as a function of time are calculated from an assumed constant worldwide clastic sedimentation rate and the relative abundance and c and s contents of the three rock types marine sandstones and shales coal basin sediments and other non marine clastics red beds arkoses by our model values of o2 versus time using a constant total sedimentation rate agree with those for variable sedimentation derived from present day rock abundances and estimates of erosional losses since deposition this agreement is the result of our reliance on the idea that any increase in total worldwide sediment burial with consequently faster burial of c and s and greater o2 production must be accompanied by a corresponding increase in erosion and increased exposure of c and s on the continents to o2 consumption via weathering it is the redistribution of sediment between the three different rock types and not total sedimentation rate that is important in o2 control to add stability to the system negative feedback against excessive o2 fluctuation was provided in the modeling by the geologically reasonable assignment of higher weathering rates to younger rocks resulting in rapid recycling of c and s we did not use direct o2 negative feedback on either weathering of c and s or burial of c because weathering rates are assumed to be limited by uplift and erosion and the burial rate of c limited by the rate of sediment deposition the latter assumption is the result of modern sediment studies which show that marine organic matter burial occurs mainly in oxygenated shallow water and is limited by the rate of supply of nutrients to the oceans by rivers results of the modeling indicate that atmospheric o2 probably has varied appreciably over phanerozoic time during the late carboniferous and permian periods o2 was higher than previously because of the rise of vascular land plants and the widespread burial of organic matter in vast coal swamps a large decrease in o2 during the late permian was due probably to the drying up of the coal swamps and deposition of a large proportion of total sediment in c and s free continental red beds sensitivity study shows that major parameters affecting results are the mean c concentration in coal basins and the relative sizes of the reservoirs of young rapidly recycled versus old rocks less sensitivity was found for changes over time in total land area undergoing weathering and the use of direct o2 negative feedback on marine carbon burial good agreement for rates of c burial calculated via our model and via independent models which are based on the use of stable carbon isotopes indicates that the dominant factor that has brought about changes in atmospheric o2 level and the isotopic composition of dissolved inorganic carbon in seawater over phanerozoic time is sedimentation and not weathering or higher temperature phenomena such as basalt seawater reaction

extreme freshwater release during the late paleozoic gondwana deglaciation and its impact on coastal ecosystems abstractstrata in the paganzo tarija and parana basins of argentina and brazil provideevidence for reconstructing the effects of late paleozoic glacial retreat the depositionalenvironment of the transgressive and early highstand ne grained deposits has been con troversial with interpretations ranging from normal marine shelves to estuaries to lakes whereas their counterparts from shallow marine settings not in uenced by glaciation hostdiverse fully marine ichnofaunas these ne grained postglacial deposits are dominatedby nonspecialized grazing trails simple feeding traces arthropod trackways and shtrails they are typical of freshwater environments and represent examples of the mermia and scoyenia ichnofacies however the local presence of acritarchs indicates sporadicmarine in uence these observations suggest a new interpretation that freshwater con ditions in fjordlike settings across south america were widespread because gondwananbasins were overwhelmed by strong meltwater discharge issuing from melting of the con tinental ice masses keywords

quantitative analysis of substrate preference in carboniferous stem group echinoids abstract a wealth of knowledge exists concerning echinoid substrate preference in recent and post paleozoic environments however relatively little is known of the environmental distribution and paleoecology of echinoids during the paleozoic the paleozoic echinoids encompass the vast majority of the echinoid stem group and were generally rare but often present in carboniferous communities across a range of paleoenvironments we analyzed substrate preference in stem group echinoids during the carboniferous period utilizing a dataset of echinoid occurrences compiled from museum collections and the literature we focused on preference for substrate lithology carbonate vs siliciclastic and grain size fine grained vs coarse grained using three different quantitative metrics we analyzed substrate preferences in five families of echinoids the palaechinidae the archaeocidaridae the proterocidaridae the lepidesthidae and the lepidocentridae broadly we found that most families showed a preference for carbonate environments however relative affinities varied amongst families the palaechinids showed a strong relative affinity for carbonate environments and were relatively more tolerant of coarse grained environments than other echinoids the archaeocidaridae showed the widest environmental tolerance of any clade with a high tolerance for siliciclastic and coarse grained substrates the proterocidaridae and lepidesthidae tended to have a relative affinity for fine grained substrates these differential tolerances and affinities for particular environments may have controlled the varying macroevolutionary histories of these clades in the late paleozoic

ichnology of a late palaeozoic ice marginal shallow marine succession talchir formation satpura gondwana basin central india abstract the late palaeozoic glaciomarine talchir formation in the satpura gondwana basin central india hosts sparse to profuse trace fossils of various kinds although sporadically among the three principal depositional systems that gave rise to the talchir succession deposits of the ice contact fan delta system and the glacial outwash braidplain delta system lack trace fossils of any kind on the other hand within the deposits of the storm wave dominated shoreface shelf system a variety of animal traces is present including simple locomotion traces and non descript bioturbation three trace fossil assemblages could be recognized within these deposits assemblage i is dominated by cylindrichnus of the skolithos ichnofacies that occurs in storm laid medium to fine sandstones deposited in shoreface and transitional shoreface inner shelf environments in contrast assemblage ii comprising dominantly horizontal grazing cum deposit feeding traces cochlichnus helminthopsis phycosiphon planolites archaeonassa and psammichnites occurs on decimeter thick sandstone beds interlayered with mudstones deposited in lower shoreface to inner shelf environments trace fossil assemblage iii is known from a 6 9 m thick outer shelf to lower shoreface progradational succession showing a vertical transition from dark gray mudstone to fine sandstone the middle part of this particular section shows rhizocorallium and flat type zoophycos whereas the upper part hosts profuse cylindrichnus along with rosselia and teichichnus in lesser proportions this assemblage is comparable to the marine ichnofacies succession combining elements of both skolithos and cruziana ichnofacies the characteristic features of the talchir trace fossil assemblages are i low ichnodiversity ii presence of forms typically found the in marine environment iii co occurrences of vertical and horizontal traces of skolithos and cruziana ichnofacies iv presence of simple structures formed by trophic generalists v abundance of certain forms and vi presence of monospecific suites these characters are akin to those of brackish water ichnofaunas in the talchir succession the transition from an ice contact fan delta system to a relatively ice free open marine system indicates an enormous flux of fresh water into the sea reducing its overall salinity predominance of annelid and worm traces and the rarity of crustacean burrows in the talchir strata also suggest a stressful environment due to the prevailing cold climate and a lower than normal marine salinity it thus appears that mixing of fresh water during deglaciation might be a key controlling factor in shaping the characters of ichnofaunas in glacially influenced shallow marine environments

the global frasnian famennian kellwasser event during the uppermostp gigas conodont zone p linguiformis zone the stepwise frasnian extinction culminates in the global transgressive regressive frasnian famennian kellwasser event most pelagic organisms of the tropical marine environment are more or less affected by this mass extinction during the early upper devonian extinction rates are clearly related to the deposition of black shales and the storage of a great amount of organic carbon in the shelf sediments contemporaneous positive excursions of the 13c recorded from pelagic limestones of europe and australia prove a worldwide change in the co2 content of the oceans surface water which is in balance with the atmosphere if the climate is controlled by the co2 content of the atmosphere a cyclic operation process might have developed with the succession transgression high organic production deposition of organic carbon lowering of co2 in the atmosphere icehouse effect polar glaciation regression erosion of organic carbon and re supply of co2 to the ocean and atmosphere greenhouse effect deglaciation transgression during the change from a greenhouse to an icehouse effect an overturn of the anoxic oceans probably was one of the causes for the mass killing of low latitude marine organisms

palaeoecology and sedimentology of carboniferous glacial and post glacial successions in the paganzo and rio blanco basins of northwestern argentina

mid carboniferous deglaciation of the protoprecordillera argentina recorded in the agua de jaguel palaeovalley abstract the agua de jaguel formation near uspallata mendoza province argentina was deposited within a palaeovalley along the southeastern margin of the calingasta uspallata basin adjacent to the protoprecordillera the basal glacigenic sequence of the formation was deposited in the serpukhovian early bashkirian near the beginning of the late palaeozoic ice age the sequence is composed of diamictite conglomerate sandstone and mudrock and records four depositional stages within a palaeofjord 1 morainal bank deposition by a wet based tidewater glacier 2 glacial retreat succession where ice retreated up the fjord out of the immediate area allowing iceberg deposition of dropstones and dump deposits 3 continued glacial retreat with ice receding onto land allowing a shoreface to develop within the palaeovalley and 4 transgression across the shoreface and resumption of iceberg deposition the thickness and facies of this succession are similar to deposits within modern alaskan fjords housing temperate tidewater glaciers comparison of the agua de jaguel formation with alaskan fjords indicates that sequence stratigraphy used for low latitude deposits must be applied with caution as glacimarine ice retreat within a fjord produces strata surfaces that are easily misidentified as flooding surfaces resulting from changes in water depth likewise the transgression during stage 4 is significant as it indicates a rise in sea level that occurred during glaciation of the protoprecordillera thus suggesting that the transgression between stages 3 and 4 was not driven by input of glacial meltwater additionally the sediment geochemistry suggests that the bottom waters of the palaeovalley were anoxic which may help explain the absence of bioturbation in the sequence as well as in other ancient glacimarine palaeovalleys the deglaciation succession and transgression are also recorded in the nearby hoyada verde and tramojo formations so it is proposed that all three formations record one glacial event in the protoprecordillera overlying fluvial and shallow marine strata in the agua de jaguel hoyada verde and tramojo formations show no indication of continued glaciation in the protoprecordillera following stage 4 and equivalent strata the deglaciation succession of the agua de jaguel formation affirms the emerging concept that the late palaeozoic ice age was characterized by alpine glaciers ice caps and small ice sheets that were not massive enough to have driven eustatic fluctuations of 100 m as previously understood and that ice never covered westernmost gondwana during later lpia events

late palaeozoic global changes affecting high latitude environments and biotas an introduction abstract the late palaeozoic ice age lpia spanning approximately from 320 ma serpukhovian late mississippian to 290 ma mid sakmarian early permian represents the vegetated earth s largest and most long lasting regime of severe and multiple glaciations involving processes and patterns probably comparable to those of the last ice age accompanying the lpia occurred a number of broadly synchronous global environmental and biotic changes these global changes as briefly reviewed and summarized in this introductory paper comprised but are not limited to the following massive continental reorganization in the lead up to the final assembly of pangea resulting in profound changes in global palaeogeography palaeoceanography and palaeobiogeogarphy substantially lowered global atmospheric carbon dioxide concentrations p co 2 coupled with an unprecedented increase in atmospheric oxygen concentrations reaching earth s all time high in its last 600 million year history sharp global temperature and sea level drops albeit with considerable spatial and temporal variability throughout the ice age and apparently a prolonged period of global sluggish macro evolution with both low extinction and origination rates compared to other times in the aftermath of the lpia the world s climate entered into a transitional climate phase through the late early to middle permian before its transformation into a greenhouse state towards the end permian in recent years considerable amount of data and interpretations have been published concerning the physical evidence in support of the lpia its broad timeframe and eustatic and ecosystem responses from the lower latitudes but relatively less attention has been drawn to the impact of the ice age on late palaeozoic high latitude environments and biotas it is with this mission in mind that we have organized this special issue with the central focus on late palaeozoic high latitude regions of both hemispheres that is gondwana and northern eurasia our aim is to gather a set of papers that not only document the physical environmental changes that had occurred in the polar regions of gondwana and northern eurasia during the lpia but also review on the biotic responses at different taxonomic ecological and spatial scales to these physical changes in a refined chronological timeframe this introductory paper is designed to provide a global context for the special issue with a brief review of key late palaeozoic global environmental changes including changes in global land sea configurations atmospheric chemistry global climate regimes global ocean circulation patterns and sea levels and large scale biotic biogeographic and evolutionary responses followed by a summary of what we see as unresolved scientific issues and various working hypotheses concerning late palaeozoic global changes and in particular the lpia as a possible reference to future research

mineralogical composition of sands in meridiani planum determined from mars exploration rover data and comparison to orbital measurements constraints on the mineralogical composition of low albedo low sulfur sands at meridiani planum are determined from mars exploration rover mer opportunity miniature thermal emission spectrometer mini tes mossbauer and alpha proton x ray spectrometer measurements results of this work show that the sand is olivine basaltic in composition with minor amounts of sulfate and a high silica phase glass or secondary amorphous silica measurements from all three instruments indicate that pyroxene is twice as abundant as olivine and that the pyroxene composition is dominated by the low calcium variety the volume abundance of olivine is constrained to be 10 15 results from detailed analyses of mer data are used to ground truth the spectral emissivity and mineral abundances derived from orbit with mars global surveyor tes data tes derived mineral abundances are within 5 of those derived from mer data which is generally within the statistical errors associated with tes derived phase abundances the agreement lends support to global and regional scale variations in mineralogical composition determined from tes data in previous studies an alternative method of least squares minimization is used for modeling the tes and mini tes data the benefits of this method are demonstrated by comparison with conventional least squares techniques previously used by tes data users

the mid carboniferous eustatic event stratigraphic and paleontologic evidence from mid carboniferous namurian basin and shelf successions in widely scattered parts of the world indicates that a major eustatic event occurred about 330 ma the event began with a regression that is recorded in most shelf sequences the regression was followed by a brief transgression about 328 ma and the event ended with a transgression that flooded large shelf areas about 325 ma the mississippian pennsylvanian unconformity in north america is a well known product of this event but equally prominent and contemporaneous unconformity surfaces are also present in europe north africa and elsewhere the event is believed to have caused numerous extinctions and it resulted in marked fluctuations in faunal diversity 94 references 2 figures

ice volume and paleoclimate history of the late paleozoic ice age from conodont apatite oxygen isotopes from naqing guizhou china abstract a high resolution and continuous conodont apatite oxygen isotope record spanning the late visean to middle permian is reported from south china which is interpreted with respect to the ice volume and or tropical seawater temperature history of the late paleozoic ice age lpia the presented 18o record shows significant fluctuations in 18o from the late visean to middle permian with highest values observed in the bashkirian early pennsylvanian the 18o maximum coincides with a major eustatic sea level fall recorded in low latitude successions and postdates the significant increases in 87sr 86sr and 13ccarb measured on well preserved brachiopod calcite which can be interpreted as reflecting intensified weathering as consequence of the closure of rheic ocean as well as enhanced carbon burial both processes may have contributed to lower greenhouse gas levels and cooled down the earth s surface triggering the maximum glaciation the high bashkirian 18o values are interpreted to represent the glacial maximum of the lpia a coeval change in faunal composition and a decreasing diversity in climate sensitive marine invertebrates can be ascribed to icehouse cooling and or loss of habitat despite inconsistencies with earlier interpretations that the early permian represented the glacial maximum of the lpia as inferred from gondwanan glacial sediments records the suggested bashkirian glacial maximum agrees well with ice extent estimates based on the regional tectonic history in gondwana which suggests that the bashkirian glaciation occurred during gondwana interior uplift promoting maximum ice cover of the entire lpia however maximum glaciation is only poorly represented in the depositional record because large parts of the glacial deposits were possibly removed by erosion as outlined by a major regional unconformity

evolution in a cold climate abstract a brief appraisal of marine fossils from high latitudes and episodically cold climate especially in east australia and new zealand during late palaeozoic and early mesozoic times shows patterns of evolution and survival that differ from those adduced for the palaeotropics and northern hemisphere examples taken from amongst phyla scyphozoa bryozoa brachiopoda and classes bivalvia and class cephalopoda suggest these attributes 1 evolution and demise of species and genera proceeded at a rate close to that known for palaeotropical and northern hemisphere macro invertebrates but involved fewer families and orders 2 possibly intraspecific variation was greater amongst southern palaeohemisphere permian species than in those of the permian palaeotropics 3 there was no proven diminution of life at the end of the guadalupian middle permian at southern high latitudes where however the fossil record is meagre for this interval younger wuchiapingian and changhsingian faunas were moderately diverse 4 there is no evidence for a high latitude southern hemisphere anoxic event in the early triassic despite claims of a world wide anoxic interval nor has any substantial volcanic eruption or bolide impact left any marked traces in the sedimentary record 5 as a consequence some major groups such as bryozoa and conulariida staurozoa survived the end permian extinction shock in the southern hemisphere 6 other major groups appear to have survived better in the south than in the north notably mollusc bivalvia and cephalopoda it therefore appears likely that triassic seas were restocked substantially from the southern hemisphere and that the permian extinction shock was asymmetric with respect to latitudes in its distribution and affect

tropical marine climate during the late paleozoic ice age using trace element analyses of brachiopods abstract the late paleozoic ice age can be considered an important analogue to the modern ice age but comparisons between the two time intervals have been hampered by the difficulty of resolving climatic changes that occur over short e g seasonal time scales in the paleozoic record as a first step toward overcoming these limitations this study employed mg ca trace element ratios sampled across the growth bands of six specimens of the brachiopod composita to assess differences in tropical marine mean temperature and seasonality in visean and moscovian time these time intervals bracket the onset of the late paleozoic ice age which occurred in mid serpukhovian time and thus provide a snapshot of climate changes from a greenhouse to an icehouse world shells were screened for diagenetic alteration by cathode luminescence and by comparing the values of mn sr na and b to those reported for modern brachiopods in addition a 87sr 86sr value measured for one specimen agreed with a published strontium isotope curve for the late paleozoic era both the mean and range of mg ca values were larger in visean than moscovian time suggesting colder and less seasonal temperatures during the late paleozoic ice age the decline in seasonality was due to a greater proportional reduction of maximum values which presumably represent summer temperatures than minimum values these relative differences between the pre ice age and ice age tropical climate provide a first step toward understanding the broad patterns of seasonal scale changes in temperature during a critical time in earth s history