palaeolatitudinal distribution of lithologic indicators of climate in a palaeogeographic framework whether the latitudinal distribution of climate sensitive lithologies is stable through greenhouse and icehouse regimes remains unclear previous studies suggest that the palaeolatitudinal distribution of palaeoclimate indicators including coals evaporites reefs and carbonates has remained broadly similar since the permian period leading to the conclusion that atmospheric and oceanic circulation control their distribution rather than the latitudinal temperature gradient here we revisit a global scale compilation of lithologic indicators of climate including coals evaporites and glacial deposits back to the devonian period we test the sensitivity of their latitudinal distributions to the uneven distribution of continental areas through time and to global tectonic models correct the latitudinal distributions of lithologies for sampling and continental area bias and use statistical methods to fit these distributions with probability density functions and estimate their high density latitudinal ranges with 50 and 95 confidence intervals the results suggest that the palaeolatitudinal distributions of lithologies have changed through deep geological time notably a pronounced poleward shift in the distribution of coals at the beginning of the permian the distribution of evaporites indicates a clearly bimodal distribution over the past 400 ma except for early devonian early carboniferous the earliest permian and middle and late jurassic times we discuss how the patterns indicated by these lithologies change through time in response to plate motion orography evolution and greenhouse icehouse conditions this study highlights that combining tectonic reconstructions with a comprehensive lithologic database and novel data analysis approaches provide insights into the nature and causes of shifting climatic zones through deep time

fluvial response to paleo equatorial climate fluctuations during the late paleozoic ice age the maritimes basin of atlantic canada preserves a 12 km thick stratigraphic succession deposited within a low latitude predominantly continental setting during the late paleozoic this paper examines the utility of using such successions for paleoclimate analysis with specific reference to changes in fluvial style modern rivers in the subhumid and semiarid tropics preserve a suite of features that are distinct from those in humid and arid environments these features include an abundance of sedimentary structures formed under froude transcritical to supercritical flow conditions and the presence of in situ vegetation growing within the channel environment this fluvial style is indicative of prolonged low flow conditions punctuated by intense precipitation events in a strongly seasonal climatic setting fluvial channel bodies within the maritimes basin preserve a remarkably similar style compared with these modern systems suggesting that a subhumid strongly seasonal paleoclimate was the dominant imprint on parts of the preserved successions strongly seasonal deposits are concentrated within four discrete stratigraphic intervals e1 e4 ranging in duration from 2 to 6 m y these intervals are correlated across the entire basin and between basins characterized by markedly different tectonic regimes which suggests that a coherent regional climate signal is recorded intervals are separated by deposits characteristic of humid and arid river systems and the alternation between these different fluvial styles implies that several pronounced long term changes in precipitation and runoff regimes occurred during the carboniferous within the region furthermore these intervals broadly coincide with major periods of southern hemisphere glaciation which suggests that glaciation had a profound and controlling effect on paleotropical climate

tracing sources of pollution in soils from the jinding pb zn mining district in china using cadmium and lead isotopes abstract systematic variations in the cd and pb isotope ratios in polluted topsoils surrounding the jinding pb zn mine in china were measured so that the sources of the metals could be traced the average 114 110cd value and 206pb 207pb isotope ratio in background soils from the region were 0 41 and 1 1902 respectively whereas the contaminated soil samples had different values with the 114 110cd values varying between 0 59 and 0 33 and the 206pb 207pb isotope ratios varying between 1 1764 and 1 1896 we also measured the cd and pb isotopic compositions in oxide ores sulfide ores and slags and found that binary mixing between ores and background soils could explain almost all of the variations in the cd and pb isotope ratios in the contaminated soils this suggests that cd and pb pollution in the soils was mainly caused by the deposition of dust emitted during anthropogenic activities mining and refining the pb and cd isotope ratios clearly showed that contamination in soils in the northeastern part of the area was caused by surface mines and zinc smelters and their slagheaps while contamination in soils in the southwestern part of the area also came from tailing ponds and underground mines the main area of soil polluted by dust from pb zn mining processes roughly extended for up to 5 km from the mine itself

organic petrology and geochemistry of the carboniferous coal seams from the central asturian coal basin nw spain abstract this paper presents for the first time a petrological and geochemical study of coals from the central asturian coal basin north spain of carboniferous pennsylvanian mainly of moscovian age a paleoenvironmental approach was used taking into account both petrographic and organic geochemical studies vitrinite reflectance r r ranges from 0 5 to 2 5 which indicates a high volatile bituminous to semianthracite and anthracite coal rank the coal samples selected for paleoenvironmental reconstruction are located inside the oil gas prone phase corresponding to the interval between the onset of oil generation and first gas generation and efficient expulsion of oil this phase is represented by coals that have retained their hydrocarbon potential and also preserved biomarker information paleodepositional reconstruction based on maceral and petrographic indices points to a swamp environment with vitrinite rich coal facies and variable mineral matter content the gelification index gi and groundwater influence index gwi indicate strong gelification and wet conditions the biomarkers exhibit a high pristane phytane ratio suggesting an increase in this ratio from diagenetic processes and a high diterpanes ratio this in turn would seem to indicate a high swamp water table and a humid climate the maximum point of coal accumulation occurred during the regressive part of the late moscovian sequence and in the most humid climate described for this period of time in the well known coal basins of europe and north america

polygenetic history of paleosols in middle upper pennsylvanian cyclothems of the illinois basin u s a part ii integrating geomorphology climate and glacioeustasy abstract distinct lateral and stratigraphic trends in paleosol morphology and clay mineralogy in conjunction with the stable isotope composition of sub millimeter scale spherulitic siderite sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian cyclic coal bearing strata of the illinois basin ib presented herein provide proxy records of middle late pennsylvanian equatorial terrestrial environments collectively these data provide a better understanding of the polygenetic history of ancient soils preserved in cyclic strata and indicate that low latitude pennsylvanian ib soil profiles were influenced by a combination of autogenic and allogenic controls lateral variations in paleosol morphology from the interior of the basin to the northern margin indicate that soil development was dominantly influenced by autogenic controls such as differences in local paleohydrology i e groundwater fluctuations and subsidence rates across the basin conversely allogenic controls i e glacioeustasy and climate are interpreted to be principally responsible for the preservation of features in gleyed protosols gleyed vertisols and gleyed calcic vertisols that occur in the interior of the ib these paleosols are characterized by a polygenetic development history that includes 1 an initial period of soil formation in well drained environments with seasonal wetting and drying of the profile followed by 2 a subsequent period of waterlogging and development of reducing conditions paleosols that lack evidence for extensive periods of waterlogging are restricted with the exception of two examples to the northern margin of the basin and they become abundant in the stratigraphic record near the middle upper pennsylvanian boundary uppermost desmoinesian the stratigraphic distribution of these paleosols in conjunction with a decrease in the relative abundance of kaolinite in the 2 m size fraction of ib paleosols near the desmoinesian missourian d m boundary is interpreted to reflect a shift in the overall low latitude regional climate to drier conditions the stable isotope compositions of sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian strata of the ib provide an additional proxy record of past equatorial terrestrial environments and are used to constrain the magnitude of paleoclimate change across the d m moscovian kasimovian boundary sphaerosiderite 18ov pdb and 13cv pdb values range from 3 6 to 0 5 and 12 8 to 3 2 respectively in particular sphaerosiderite 18o values from the b horizons of paleosols display an approximate 1 5 shift across the d m boundary this stratigraphically short isotopic shift occurs across the d m boundary on the order of one cyclothem 400 kyr and is followed by a subsequent shift on the order of one cyclothem back to more positive siderite 18o values the average 18ov smow and dv smow values of kaolinite isolated from the 0 2 m size fraction of a latest desmoinesian flint clay breccia are 21 0 and 46 5 these values correspond to a latest desmoinesian crystallization temperature of 27 2 c and a meteoric water 18ov smow value of 3 1 combination of sphaerosiderite 18o values and co occurring flint clay kaolinite d and 18o values suggest a possible warming of up to 6 c across the d m boundary corresponding to an approximate temperature change of siderite crystallization from 27 to 33 c this temperature increase in conjunction with distinct stratigraphic trends in the clay mineralogy and morphology of ib paleosols is consistent with previous paleoclimate interpretations and it suggests that low latitude pennsylvanian paleoclimate became drier and warmer across the d m boundary

eccentricity paced late paleozoic climate change abstract cyclic sedimentary deposits characterize low latitude late paleozoic successions and preserve evidence of dynamic climate change on the pangaean supercontinent although their orbitally paced glacioeustatic origins are widely accepted their climatic signatures are open to interpretation in this study we utilize the genesis general circulation model gcm coupled to dynamic ice sheet and ecosystem components to explore the response of low latitude continental climate and high latitude ice sheets to orbital and atmospheric pco2 forcing our results suggest that atmospheric pco2 concentration exerts the primary control over low latitude continental climate and high latitude glaciation our experiments constrain the atmospheric pco2 window within which late paleozoic climate was amenable to orbitally driven glacial interglacial fluctuations the results suggest that both high latitude ice sheet accumulation and ablation and low latitude climate change were paced by the eccentricity of earth s orbit periods of high eccentricity amplified precession driven changes in insolation and promoted high latitude ice sheet volume fluctuations as well as increased low latitude precipitation variability when eccentricity was low the amplification of precessionally driven insolation fluctuations was reduced which promoted high latitude continental ice sheet stability and less variable low latitude precipitation based on these modeling results we discuss the implications of eccentricity paced precessional scale climatic changes on low latitude pangaean depositional environments

controls on permo carboniferous precipitation over tropical pangaea a gcm sensitivity study abstract a series of late paleozoic climate model simulations was developed using the genesis atmospheric general circulation model to investigate the independent roles of gondwanan deglaciation atmospheric co 2 rise and regional tectonism on the long term 10 6 yr evolution of continental precipitation over tropical pangaea the model results indicate that either deglaciation or a co 2 increase from 1 to 8 present atmospheric levels could have caused substantial drying and warming at low latitudes a result that is consistent with late paleozoic proxy records yet the atmospheric processes that led to drying differ between these cases the deglaciation of gondwana reduces low latitude temperature gradients in the southern hemisphere decreasing by as much as 60 the meridional overturning in the southern hemisphere winter cell of the hadley circulation the decline in overturning reduces convective precipitation over equatorial pangaea in contrast high levels of co 2 have little effect on the large scale meridional overturning circulation but increase continental temperatures leading to high evaporation rates and reduced available soil moisture the source of convective precipitation on land in comparison to deglaciation and p co 2 regional uplift erosion of the central pangaean mountains cpms has a secondary effect on tropical precipitation in genesis and cannot explain the long term aridification and warming of western pangaea we suggest that the deglaciation of gondwana and a concomitant rise in atmospheric p co 2 could explain much of the late paleozoic climate change over low latitude pangaea

late pennsylvanian early permian vegetational transition in oklahoma palynological record abstract the wabunsee carboniferous virgilian through sumner permian leonardian groups of oklahoma preserve a record of terrestrial and nearshore marine environments during glacio eustatic fluctuations caused by southern hemisphere glaciation this section with the pennsylvanian permian boundary firmly established in the red eagle formation on the basis of conodonts permitted study of vegetational change across the boundary interval the palynology of 43 productive samples from five cores in kay and osage counties in oklahoma was investigated palynomorphs were assigned to eight morphologic groups that also reflect climate preferences four distinct palynofloras are recognized the three transitions between them in the lower council grove middle chase and lower sumner groups are abrupt and in succession consistent with an interpretation of increasing seasonality aridity from latest pennsylvanian into the early permian none of these floristic transitions align with the conodont based boundary or with any lithostratigraphic group boundary these palynological data from oklahoma are in accord with previous data from kansas that also demonstrated no palynological shift at the boundary and increased seasonality aridity through this period comparison of the palynofloras from oklahoma kansas and the boundary interval of the pennsylvanian permian boundary type section in aidaralash creek in kazakhstan reveals differences in composition that suggest local to regional including climatically induced heterogeneities that may present an obstacle to confident palynologically based global correlations in fully terrestrial sections

from cyclothems to sequences the record of eustasy and climate on an icehouse epeiric platform pennsylvanian permian north american midcontinent the stratigraphic succession of the north american midcontinent contains a high resolution 100 000 year record of sea level and climate change spanning the pennsylvanian permian boundary outcrop based sequence stratigraphic analysis on the upper wabaunsee admire and lower council grove groups in kansas and nebraska reveals a hierarchy of fifty one fifth order meter scale cycles grouped into five fourth order composite sequences fifth order cycles are bounded by subaerial unconformities in nearshore settings and correlative conformities in offshore settings and are therefore very thin depositional sequences lowstand systems tracts observed only in nearshore deposits are expressed as sandy incised valley fills in these meter scale cycles transgressive systems tracts which are dominated by carbonate deposition include coastal evaporites indicating arid climatic conditions highstand systems tracts which are dominated by siliciclastic deposition include thin but persistent coals in muddy coastal successions indicating humid climatic conditions paleosols at sequence boundaries evolve from vertic to calcic indicating climate change from relatively humid to relatively arid conditions during subaerial exposure this indicates that relatively arid climate coincided with eustatic lows while relatively humid climate coincided with eustatic highs on this low latitude platform composite sequences are bounded by subaerial angular unconformities and display a transgressive regressive stacking pattern of meter scale cycles the high resolution stratigraphic record of the midcontinent helps constrain the rate and magnitude of environmental change in ancient icehouse conditions and can serve as a baseline of environmental change for comparison with other coeval successions

the so called paleophytic mesophytic transition in equatorial pangea multiple biomes and vegetational tracking of climate change through geological time abstract the paleophytic mesophytic and cenophytic were originally conceptualized as chronostratigraphic intervals not specific floras and were used principally in that way for about 100 years they supposedly reflected massive irreversible biotic changes on land that were thought to have happened about half a geological period prior to the changes in marine faunas that mark the more traditional geological era boundaries the terms were applied initially only to terrestrial rocks from the euramerican portions of equatorial pangea especially parts of central europe where the boundary between the paleophytic and mesophytic the eras of interest here was placed at the top of the german rotliegends more recently the terms have been coopted to describe vegetation types not chronostratigraphic units even to the point where specific linnean ordinal or class level clades evolutionary lineages of plants have been attributed solely to one vegetation type or the other at a global level furthermore the paleophytic mesophytic transition has been recognized in the largely taxonomically distinct vegetation types of temperate as well as the equatorial paleolatitudes the result of this conceptual coopting of terms that already were of questionable value is a blurring of the concepts almost to the point of meaninglessness a reading of the literature indicates confusion in terms of what represents the paleophytic flora vs the mesophytic flora the botanical basis for the floras and the taxonomic scale at which they can be recognized the geographic pattern and temporal correlation of the supposed transition and the evolutionary and ecological significance of the vegetational changes these terms supposedly capture we propose that these terms be completely and utterly abandoned as confusing and worse yet misleading evidence suggests that paleozoic vegetation tracked climate which should not come as a surprise in light of what is known of plant dynamics in the holocene and recent furthermore the evidence for a global paleophytic vs mesophytic vegetation is simply unsubstantiated by the fossil record rather there appears to have been a complex of global species pools reflecting climate at many spatio temporal scales the vegetational changes occurring in the late paleozoic thus can be understood best when examined as spatial temporal changes in biome scale species pools responding to major global climate changes locally and regionally manifested

walther s law climate change and upper paleozoic cyclostratigraphy in the ancestral rocky mountains geologists routinely apply walther9s law in interpreting paleoenvironments and paleogeographic scenarios from stratigraphic successions the application of walther9s law however may be problematic in strata that have been influenced by significant and geologically rapid climate change such climatic fluctuation can force depositional environments to change fundamentally rather than migrate laterally resulting in a stratigraphic succession wherein depositional facies vertically superposed rarely or never coexisted laterally upper pennsylvanian carbonate siliciclastic cycles deposited in basins of the southern ancestral rocky mountains display stratigraphic relations that cannot be explained by autogenic and or glacioeustatic mechanisms alone rather intracyclic glacial interglacial climate change was a significant influence cycles of the northern pedregosa basin for example comprise eolian marine siltstone in sharp contact with subtidal peritidal carbonate facies absence of facies mixing suggests a climatic control on silt influx cycles of the western orogrande basin comprise deltaic siliciclastic strata in sharp contact with subtidal peritidal carbonate facies absence of facies mixing truncated siliciclastic progradation and carbonate facies with emergence features similarly support a climatic influence on the siliciclastic component in both systems intracyclic glacial interglacial climatic shift reconfigured depositional environments in cases such as these application of walther9s law could produce erroneous conclusions severe glacial interglacial climate change helps explain the pervasive association of mixed carbonate siliciclastic cyclicity that typifies upper paleozoic strata in many parts of the world

reconstruction of a late cisuralian early permian floodplain lake environment palaeontology and sedimentology of the tregiovo basin trentino alto adige northern italy abstract the late cisuralian is known as a time of increasing aridity compared to the late pennsylvanian early cisuralian although several studies highlighted this trend at low latitudes of western pangaea little is known from central pangaea environments the discovery of new fossiliferous horizons in the late cisuralian tregiovo formation northern italy allowed a new palaeoenvironmental study based on facies analysis ichnology palaeobotany plant insect interaction and palynology three facies associations were identified a c and correspond to floodplain lake ephemeral lacustrine and distal alluvial fan environments respectively the tetrapod ichnoassociation is more diverse than previously known including abundant diapsid and non diapsid reptile tracks and rarer temnospondyl amphibian tracks plant fossils are characterized by a predominance of hinterland taxa conifers hygrophytic plants are present as well the sporomorph association is dominated by miospores of cordaitales voltziales and peltaspermales while trilete lycopsid and fern miospores are rare which corresponds well with the macroflora invertebrate trace fossils and feeding traces on plant fossils are described for the first time from the tregiovo basin suggesting transitional low energy environments and a relatively low level of herbivory respectively this study evidences the development in the tregiovo basin of a wet and dry probably seasonal climate which became drier between facies associations a b this environment constitutes an important reference since few data are known to infer the late cisuralian climatic conditions of central pangaea

stratigraphic distribution of macerals and biomarkers in the donets basin implications for paleoecology paleoclimatology and eustacy abstract more than one hundred and thirty coal seams and coaly layers occur in the donets basin donbas twenty eight 52 samples of them ranging in age from serpukhovian late mississipian to gzhelian late pennsylvanian 33 clastics and three limestones were studied in terms of maceral composition sulphur contents and biomarker distribution diterpanes are used to estimate the contribution of different groups of plants and the height of the water table in the swamp hopanes are a measure of bacterial activity in the peat and steranes indicate the relative input of wood and algae stratigraphic trends in these parameters are discussed in relation to paleoenvironment climatic changes and eustacy a tropical climate prevailed in the donbas from serpukhovian to kasimovian times nevertheless periods with drier and wetter conditions can be distinguished based on maceral and biomarker data relatively dry conditions are observed during serpukhovian and vereian times whereas wetter climates with a maximum of coal deposition occurred during the late bashkirian most of the moscovian and the earliest kasimovian no economic coal seams are hosted in upper kasimovian and gzhelian deposits a result of a change to an arid climate our data also suggest climatic changes during sequences of different order for the second order third order and fourth order sequences relatively dry or wet conditions occurred during coal deposition in the lowstand systems tract an intermediate climate during the transgressive systems tract and the maximum flooding and a wet climate during the highstand systems tract the results for high frequency sequences support the cecil s paleoclimatic model an intermediate paleoclimate during lst sandstone and levee siltstone a wet climate during early tst coal and a dry climate during late tst limestone mfs claystone and hst deltaic siltstone coals deposited during maximum flooding periods are more enriched in c27 steranes derived from algae and contain lower proportions of c29 steranes derived from the wood of higher plants

the sedimentology paleoenvironment and diagenesis of the asencio formation of western uruguay abstract the uppermost sandstones of the asencio formation of southwestern uruguay are characterized by a striking iron rich geochemical overprint which has been interpreted as paleopedogenic in origin among the notable features of the asencio is the extension of the overprint into tubes that extend several meters into the underlying mercedes formation field observations and geochemical analyses of the asencio formation and its parent lithologies from four localities around uruguay allow the identification of the asencio overprint as a ferricrete displaying a number of the features typically associated with ferricrete formation iron and aluminum enrichment conversion of labile minerals to kaolinite vermiform pseudoconglomeratic and mottled textures and loss of bulk density in comparison to the unmodified parent the nature and uniformity of the geochemical profiles through the asencio formation suggests that this paleopedogenic modification occurred during a single phase of intense tropical weathering on a stable land surface possibly over a geologically short time period paleoenvironmental proxies suggest this weathering could have occurred at temperatures around 18 c with about 1500 mm of precipitation although these proxies are not developed for paleosols lacking a strong bt horizon like the asencio no existing hypotheses can satisfactorily explain the nature of the tubes extending from the base of the asencio formation nor do any of the observed features aid in the dating of the asencio

a record of glacial aridity and milankovitch scale fluctuations in atmospheric dust from the pennsylvanian tropics abstract atmospheric dust is an important climatic agent as well as a valuable climatic archive this study documents systematic variations in a single upper pennsylvanian shallow water carbonate buildup of the midland basin west texas that was isolated from fluvio deltaic input and consists almost entirely of carbonate bounded by sequence boundaries thin 0 02 to 1 m intervals of dark pyritic siliciclastic mudrock with subtle pedogenic features occur commonly at the sequence boundaries and are interpreted as loessite deposited during lowstands primarily on the basis of paleogeographic isolation of the buildup the silicate mineral fraction smf extracted from the underlying carbonate which includes quartz clay and trace feldspars and heavy minerals varies in concentration weight from 0 015 to 6 69 in the carbonate this smf contains both fine grained detrital and authigenic silica interpreted to be eolian on the basis of geochemical petrographic and grain size characteristics as well as paleogeography hence the smf is considered a proxy for atmospheric dust whole rock geochemistry suggests that the dust was at least partly derived from uplifts of the ancestral rocky mountains with a possible minor contribution from active volcanic centers located to the present day south and southwest the estimated mean accumulation rate mar of dust in highstand carbonate facies full interglacial relative to carbonate facies that formed during relative fall in sea level suggest that dust flux increased 4 to 10 times accompanying the transition to glacial conditions mars in the siliciclastic mudrock which accumulated at lowstand full glacial to incipient transgression suggest glacial phase increases in dust flux of nearly 400 to 4000 times relative to full interglacial conditions spectral analyses of dust abundance through the study section show variations consistent with milankovitch forcing

sedimentary cyclicity in the marine pliocene pleistocene of the wanganui basin new zealand sequence stratigraphic motifs characteristic of the past 2 5 m y earth s climatic history since 2 5 ma has been controlled by milankovitch variations in the planetary orbit comprising alternate periods of glaciation and interglaciation with a dominant frequency of 41 000 yr concomitantly eustatic sea level has fluctuated 70 to 130 m causing rapid transgressions and regressions of the shoreline across the world s continental shelves the resulting sedimentary record is cyclothemic each cyclothem corresponding to a single climate and sea level cycle the wanganui basin new zealand contains a 2 km thick almost complete composite record since isotope stage 100 ca 2 5 ma in the form of 47 superposed cyclothems of shelf origin each cyclothem corresponds to an unconformity bound stratigraphic sequence and typically contains a transgressive systems tract sometimes a mid cycle shell bed a highstand systems tract and sometimes a regressive systems tract no advantage accrues from using transgressive regressive units rather than cyclothems and or sequences in description of the succession six basic sequence motifs represent deposition in locations between the shoreline and offshore shelf i e the hawera birdgrove turakina seafield castlecliff and rangitikei motifs a seventh the nukumaru motif which includes dominant coquina limestone represents deposition in shallow water areas of reduced terrigenous sediment on the flank of the basin the sequence motifs represented in any section change systematically in sympathy with basin scale changes in subsidence and sediment supply in contrast with the 41000 year length of individual glacioeustatic sequences these basin wide tectonic cycles have a periodicity of many hundreds of thousands to a few million years i e that of third or fourth order sequences of the exxon type this coupled with the restriction of strongly cyclothemic sediments to geological periods of known glacio eustasy permiancarboniferous pliocene pleistocene suggests that tectonic subsidence cycles rather than glacio eustasy are the driving forces behind the development of the third and fourth order unconformity bound sequences that are reported to occur throughout the stratigraphic record

provenance of permian triassic and ordovician metagraywacke terranes in new zealand evidence from 40ar 39ar dating of detrital micas single crystal 40 ar 39 ar ages of detrital micas from greenland group ordovician low grade metagraywackes of the west coast south island new zealand indicate a source area having muscovite age patterns of 490 515 ma the detrital muscovite ages are characteristic of granitoid and gneiss terranes of the ross adelaide fold belt of antarctica therefore the source area for the greenland group sedimentary rocks was the immediately adjacent pacific margin of gondwana similar age determinations for rakaia terrane permian triassic torlesse supergroup metagraywackes of the wellington and canterbury regions of new zealand indicate that their source area included rocks having prominent muscovite cooling ages populations of 210 290 ma 80 and 410 460 ma 15 the torlesse detrital muscovite age data thus suggest that the source area of the metagraywackes was not within the lachlan fold belt of southeast australia and analogues in antarctica nor in the adjacent ross adelaide fold belt rather the rakaia terrane of the torlesse metagraywackes is a true suspect terrane derived from a source area within the hunter bowen fold belt of northeast australia and the immediately adjacent older orogens of eastern queensland

styles of interaction between aeolian fluvial and shallow marine environments in the pennsylvanian to permian lower cutler beds south east utah usa the pennsylvanian to permian lower cutler beds comprise a 200 m thick mixed continental and shallow marine succession that forms part of the paradox foreland basin fill exposed in and around the canyonlands region of south east utah aeolian facies comprise i sets and compound cosets of trough cross bedded dune sandstone dominated by grain flow and translatent wind ripple strata ii interdune strata characterized by sandstone siltstone and mudstone interbeds with wind ripple wavy and horizontal planar laminated strata resulting from accumulation on a range of dry damp or wet substrate types in the flats and hollows between migrating dunes and iii extensive near flat lying wind rippled sandsheet strata fluvial facies comprise channel fill sandstones lag conglomerates and finer grained overbank sheet flood deposits shallow marine facies comprise carbonate ramp limestones tidal sand ridges and bioturbated marine mudstones during episodes of sand sea construction and accumulation compound transverse dunes migrated primarily to the south and south east whereas south westerly flowing fluvial systems periodically punctuated the dune fields from the north east several vertically stacked aeolian sequences are each truncated at their top by regionally extensive surfaces that are associated with abundant calcified rhizoliths and bleaching of the underlying beds these surfaces record the periodic shutdown and deflation of the dune fields to the level of the palaeo water table during episodes of aeolian quiescence fluvial systems became more widespread forming unconfined braid plains that fed sediment to a coastline that lay to the south west and which ran approximately north west to south east for at least 200 km shallow marine systems repeatedly transgressed across the broad low relief coastal plain on at least 10 separate occasions resulting in the systematic preservation of units of marine limestone and calcarenite between units of non marine aeolian and fluvial strata to form a series of depositional cycles the top of the lower cutler beds is defined by a prominent and laterally extensive marine limestone that represents the last major north eastward directed marine transgression into the basin prior to the onset of exclusively non marine sedimentation of the overlying cedar mesa sandstone styles of interaction between aeolian fluvial and marine facies associations occur on two distinct scales and represent the preserved expression of both small scale autocyclic behaviour of competing coeval depositional systems and larger scale allocyclic changes that record system response to longer term interdependent variations in climatic and eustatic controlling mechanisms the architectural relationships and system interactions observed in the lower cutler beds demonstrate that the succession was generated by several cyclical changes in both climate and relative sea level and that these two external controls probably underwent cyclical change in harmony with each other in the paradox basin during late pennsylvanian and permian times this observation supports the hypothesis that both climate and eustasy were interdependent at this time and were probably responding to a glacio eustatic driving mechanism

amphibian burrows and ephemeral ponds of the lower permian speiser shale kansas evidence for seasonality in the midcontinent abstract burrows attributed to the lysorophid brachydectes elongatus occur within a green mudstone lens in the lower permian wolfcampian speiser shale council grove group of eastern kansas the burrow bearing unit consists of a 100 m long lens of massive calcareous silty mudstone with a maximum thickness of 35 cm the lens also contains the fossils of fish amphibians reptiles charophytes stomachara and ostracodes carbonita the mudstone lens pinches out laterally into red pedogenically modified mudstone the burrows occur in three layers at the top of each layer is a subaerial exposure surface indicated by rhizoliths mudcracks and coarse grained lags the mudstone lens is interpreted as the deposit of a shallow ephemeral pond the burrows occur in three vertically and temporally separated clusters with concentrations up to 20 m2 the burrows show two types of architecture type i burrows are elongate elliptical tubes 4 32 cm long and 2 7 cm in width type ii burrows are short elliptical tubes 1 5 3 5 cm in length and 2 5 5 cm in width the burrow fill consists of a mudstone capped by sandy siltstone each burrow layer contains a varying number of articulated and disarticulated lysorophid skeletons within the burrows and surrounding matrix while similar to permian lungfish burrows the architecture and surficial morphology of the lysorophid burrows permits their distinction even in the absence of body fossils the occurrence of burrow layers capped by subaerial exposure surfaces and separated by layers of non burrowed massive mudstone indicates that burrowing occurred in response to episodic perhaps seasonal droughts on the permian coastal plain the lysorophid burrowing behavior is analogous to that of the extant amphibians amphiuma sp and siren intermedia which inhabit rivers and ponds in the southeastern usa

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

lower permian wolfcampian paleosol bearing cycles of the u s midcontinent evidence of climatic cyclicity lower permian sedimentary cycles of the north american midcontinent consist predominantly of very shallow marine and paralic facies and well developed stacked paleosol profiles although recording glacio eustatic sea level fluctuations these cycles also contain evidence of cyclic climate change this evidence includes the repeated carbonate to clastic facies pattern observed for meter scale cycles and the regionally consistent change from calcic to vertic paleosols within the variegated mudstones of most cyclothems climates are interpreted to have fluctuated from arid or semiarid conditions to seasonally wet dry conditions during the course of a single cyclothem furthermore within the midcontinent drier conditions appear to have characterized times of sea level rise and highstand whereas wetter more seasonal conditions characterized times of sea level fall and lowstand this relationship is interpreted to have resulted from variations in the intensity of a pangean monsoon generated by glacial interglacial cycles

a model based evaluation of tropical climate in pangaea during the late palaeozoic icehouse abstract the late palaeozoic ice age lpia is the earth s penultimate icehouse climate geological proxies for tropical pangaean climate during the lpia are significantly modulated on 100 400 kyr and sub 100 kyr scales in addition some geological proxies suggest that equatorial continental areas may have been colder and more arid during lpia glacial intervals than during late cenozoic glacial intervals furthermore the relationship between polar and tropical climate variability remains controversial the climate dynamics underlying these phenomena are only partly understood nevertheless past modeling of lpia climate has suggested that precipitation near the equator was modulated by monsoonal circulation that itself was modulated by orbital variability here the earth s climate during asselian sakmarian time 299 284 ma was simulated with the community climate system model version 3 ccsm3 these simulations address model climate sensitivity to direct and indirect effects of glaciation as well as variability in the earth s orbit the results of these simulations suggest that sea level and orbitally forced monsoon variability were the primary controls on tropical precipitation when ice sheets were confined to polar latitudes any impact of orbital forcing on glaciation therefore could have led to aliasing between glacial and monsoonal effects in particular regions perhaps explaining contrasting geologically based interpretations of how tropical climate responded to glaciation glaciation of the central pangaean mountains would have led to widespread cold and aridity in equatorial pangaea but forming these glaciers would have required an unknown additional climate forcing with an unknown impact on tropical precipitation

environmental significance of lungfish burrows gnathorhiza within lower permian wolfcampian paleosols of the us midcontinent abstract burrows of the lungfish gnathorhiza occur in the fine grained strata of the lower permian wolfcampian blue spring shale member of the matfield formation near manhattan kansas thousands of lungfish burrows occur in three beds of a compound paleosol profile with the vast majority confined to a single bed several meters below the florence limestone member of the barneston limestone chase group the burrows a high percentage of which contain lungfish bones occur in a 145 m long lens shaped unit comprised of clayey siltstone that exhibits platy to subangular blocky peds and downward and laterally branching thin rhizoliths the uppermost paleosol horizon in each level is gleyed indicating that there was standing water for part of the year the paleoecosystem represented by these units formed in a low lying terrestrial coastal paleolandscape with subtle topography and imperfectly drained paleosols equivalent to present day aquents these paleosols are part of a pedogenic sequence recording an upward climatic trend from semi arid to monsoonal

the role of climate in stratigraphic patterns exhibited by late palaeozoic rocks exposed in kansas abstract late palaeozoic cyclothems of the midcontinental u s cannot be represented by a single ideal facies sequence rather they encompass a wide range of cycle types depending on their stratigraphic position the exposed late palaeozoic pennsylvanian and permian rocks of kansas as compiled by zeller 1968 can be divided into nine major lithofacies these lithofacies were ordered based on their times of greatest abundance through the section from oldest to youngest they attain their peak abundance in the following order 1 coal 2 gray mudrocks and sandstones 3 black mudrocks 4 limestones 5 cherty limestones 6 fossiliferous mudrocks 7 variegated mudrocks 8 evaporites and 9 variegated dolomitic siliciclastics climatically these nine lithofacies suggest a change from generally wetter at the base to generally drier at the top of the section this climatic trend was probably generated by a complex interaction of factors primarily driven by global tectonics climatic changes can be used to explain the five generally recognized types of lithofacies cyclothems in kansas and thus are a potential explanation for the changing stratigraphic patterns of the entire late palaeozoic time interval of kansas and perhaps elsewhere

high resolution geochemistry and sequence stratigraphy of the hushpuckney shale swope formation eastern kansas implications for climato environmental dynamics of the late pennsylvanian midcontinent seaway abstract the hushpuckney shale member of the swope formation missourian stage eastern kansas is the core shale of a kansas type cyclothem formed during the late transgressive to early regressive phases of a late pennsylvanian glacio eustatic cycle coeval high frequency climato environmental dynamics of the midcontinent seaway are preserved in the kgs orville edmonds no 1a study core as centimeter scale variation in major components organic carbon authigenic sulfides and phosphate detrital siliciclastics organic macerals trace element redox proxies mo u v zn and ichnofabric features benthic o 2 levels declined sharply from the base of the black shale 0 cm went sulfidic at 4 cm and reached a redox minimum at 21 cm above this level redox potential gradually rose fluctuating between sulfidic and nonsulfidic conditions from 35 cm to the black shale gray shale contact at 52 cm onset of dysoxic conditions at that contact allowed establishment of a benthic community of soft bodied organisms comprised of deep tiered tracemakers tolerant of low o 2 conditions trichichnus and shallow tiered tracemakers favoring soupground helminthopsis or firmground substrates the zoophycos phycosiphon schaubcylindrichnus planolites association most geochemical records exhibit a low order cycle spanning the full 52 cm thickness of the black shale submember reflecting a dominant glacio eustatic control the base and top of the black shale submember record lateral migration of the pycnocline across the midcontinent shelf during the transgressive and regressive phases respectively the maximum flooding surface mfs is at 17 23 cm an interval containing the euxinic peak and characterized by high concentrations of illite representing a cratonic siliciclastic flux and terrestrial organic macerals the product of transient increases in humidity weathering rates and the export of coal swamp vegetation associated with the interglacial highstand of the swope cyclothem although a transgressive surface of maximum starvation sms cannot be confidently identified a phosphate rich regressive condensation surface at 28 34 cm records pycnoclinal weakening due to increased aridity associated with renewed southern hemisphere icesheet growth a correlative shift in dominance from terrestrial to marine derived organic macerals reflects increased upwelling of nutrient rich deepwaters and enhanced primary productivity penecontemporaneous paleogeographic and climatic factors e g semirestricted circulation monsoonal precipitation predisposed the midcontinent seaway toward sensitivity to high frequency climato environmental fluctuations which are preserved as 2 to 7 cm thick cycles in the study core the 52 cm thick black shale submember contains 12 such high order cycles which have an estimated average duration of 2 to 9 kyr implying a sub milankovitch band i e millennial scale climatic control the results of this study are relevant to the sequence stratigraphic interpretation of kansas type cyclothems the dynamics of gondwanan ice age glacio eustatic cycles and the development of boundary conditions for late pennsylvanian paleoclimate models