a transitional alkalic dolerite dike suite of mesozoic age in southeastern new england dike rocks from the new england platform of rhode island and adjacent massachusetts consist of premetamorphic and post metamorphic suites the older group includes metamorphosed dolerite minette and schistose dioritic rocks post metamorphic dikes consist of dolerite and sparse monchiquite the post metamorphic dolerites are of comparable age to the eastern north american dolerite suite associated with the mesozoic basins along the eastern seaboard of north america however the southeastern new england dolerites exhibit mineralogy and chemistry more typical of a transitional alkalic suite compared to the more subalkalic tholeiitic dolerites of the eastern north american suite both suites are compatible with a rift tectonic setting but the more alkalic dolerites may represent a deeper source of small volume melts compared to the eastern north american dolerites these more alkaline melts may have concentrated at local centers or they may be typical of flank dolerites as opposed to the less alkalic varieties that occur within the central axial rift

the mamonia complex sw cyprus revisited remnant of late triassic intra oceanic volcanism along the tethyan southwestern passive margin upper triassic volcanic and sedimentary rocks of the mamonia complex in southwestern cyprus are exposed in erosional windows through the post cretaceous cover where the mamonia complex is tectonically imbricated with the troodos and akamas ophiolitic suites most of these upper triassic volcanic rocks have been considered to represent remnants of triassic oceanic crust and its associated seamounts new nd and pb isotopic data show that the whole mamonia volcanic suite exhibits features of oceanic island basalts oib four rock types have been distinguished on the basis of the petrology and chemistry of the rocks volcanism began with the eruption of depleted olivine tholeiites type 1 and oceanic island tholeiites type 2 associated with deep basin siliceous and or calcareous sediments the tholeiites were followed by highly phyric alkali basalts type 3 interbedded with pelagic halobia bearing limestones or white reefal limestones strongly lree enriched trachytes type 4 were emplaced during the final stage of volcanic activity nd and pb isotopic ratios suggest that tholeiites and mildly alkali basalts derived from partial melting of heterogeneous enriched mantle sources fractional crystallization alone cannot account for the derivation of trachytes from alkaline basalts the trachytes could have been derived from the partial melting at depth of mafic material which shares with the alkali basalts similar trace element and isotopic compositions this is corroborated by the rather similar isotopic compositions of the alkali basalts and trachytes the correlations observed between incompatible elements nb th and varepsilon nd and pb isotopic initial ratios suggest that the mamonia suite was derived from the mixing of a depleted mantle dmm and an enriched component of high 238u 204pb himu type models using both nd and pb isotopic initial ratios suggest that the depleted tholeiites type 1 derived from a dmm source contaminated by an enriched mantle type 2 component em2 and that the oceanic tholeiites type 2 alkali basalts type 3 and trachytes type 4 were derived from the mixing of the enriched mantle source of the depleted tholeiites with a himu component none of the mamonia volcanic rocks show evidence of crustal contamination the upper triassic within plate volcanism likely erupted in a small southerly neotethyan basin located north of the eratosthenes seamount and likely floored by oceanic crust

quantitative radiometric and biostratigraphic calibration of the pennsylvanian early permian cisuralian time scale and pan euramerican chronostratigraphic correlation a quantitative biostratigraphic and radiometric calibration is presented for the pennsylvanian through early permian global time scale based upon high precision isotope dilution thermal ionization mass spectrometer id tims u pb zircon ages for interstratified ash beds in the parastratotype sections of the southern urals of russia twenty four ash bed ages in three outer ramp and basinal sections of the pre uralian foredeep bracket the biotic definitions of global stages and regional substages from the base of the upper pennsylvanian kasimovian stage to the base of the lower permian artinskian stage four additional ash bed ages in two sections of the eastern slope of the urals constrain the global bashkirian and serpukhovian stages quantitative stratigraphic methods conop9 are applied to a compilation of over 2000 bioevents in 22 stratigraphic sections supplemented by our dated volcanic horizons to refine the pennsylvanian early permian global time scale significant shifts in the duration of several stages are demonstrated ranging from one to six million years compared with prior estimates the unprecedented density of radiometric calibration points for the pennsylvanian permian transition provides a high resolution 0 1 ma global chronostratigraphic standard for testing and improving biostratigraphic correlations across euramerica we integrate radiometric ages biostratigraphic correlation and cyclostratigraphic tuning of major cyclothems to the long period 404 ka eccentricity cycle to elucidate the tempo magnitude and forcing of eustatic changes and cyclothemic deposition associated with the waxing and waning of gondwanan ice sheets and establish a pan euramerican chronostratigraphic framework for most of pennsylvanian and early permian time

chronostratigraphy and paleoclimatology of the lodeve basin france evidence for a pan tropical aridification event across the carboniferous permian boundary abstract paleosols preserved within the carboniferous permian succession of the lodeve basin massif central france change stratigraphically from histosols to calcic vertisols and calcisols to gypsic vertisols and ultimately back to calcic vertisols and calcisols new high precision u pb zircon ages ca idtims for tuff beds within the lodeve and adjacent graissessac basins significantly revise the chronostratigraphy of these and correlated permian terrestrial basins of eastern euramerica under the newly revised chronostratigraphy presented here these stratigraphic changes in morphology indicate a substantial drying of paleoenvironments across the carboniferous permian boundary with a trend toward progressively more arid and seasonal climates through most of the early permian this newly realized chronology provides a paleoenvironmental and paleoclimatic timeline for eastern tropical pangea that is contemporaneous with similar records in western pangea and suggests pan tropical progressive climate change toward aridity and seasonality occurred from the late carboniferous through early permian

an enigmatic conchostracan fauna in the eastern dead sea region of jordan first records of rossolimnadiopsis novozhilov from the early triassic ma in formation abstract the late permian early triassic sedimentary succession in the eastern dead sea region of jordan was surveyed for conchostracans crustacea branchiopoda whereas their occurrence in the middle late permian umm irna formation could not be confirmed the overlying ma in formation contained a fauna comprising rossolimnadiopsis novozhilov and other thus far taxonomically undetermined conchostracans here a new species rossolimnadiopsis hanskerpi nov sp is described and figured it shows a very distinctive concavely curved dorsal margin and an elevated outwardly curved semi circular flange rossolimnadiopsis hanskerpi nov sp occurs in dark gray laminated lacustrine siltstones of the ma in formation nimra member which is considered to be of early triassic age based on literature data rossolimnadiopsis was previously recorded only from two localities in the moscow syncline in central russia in addition to jordan the genus has been identified in india and possibly in germany all these occurrences seem to be restricted to a narrow stratigraphic interval ranging from the late permian to the early triassic

origin and significance of tourmaline rich rocks in the broken hill district australia tourmaline rich rocks are widespread minor lithologies within the early proterozoic willyama supergroup in the broken hill district australia tourmaline concentrations occur in strata bound and local stratiform tourmalinites clastic metasedimentary rocks quartz gahnite lode rocks stratiform pb zn ag sulfide ores garnet quartzites strata bound scheelite deposits quartz tourmaline nodules discordant quartz veins and granitic pegmatites most of the tourmaline rich rocks are within the broken hill group that hosts the main pb zn ag ores at the globe mine along the northeast end of the main lodes tourmalinites are closely associated with pb zn ag mineralization and in places are interbedded with mn rich garnet quartzites galena and other ore minerals occur locally in the cores of recrystallized tourmaline grains in these tourmalinites indicating that tourmaline and sulfides were present together prior to deformation and high grade metamorphism electron microprobe analyses of tourmalines intergrown with fe sulfides at the globe mine show mg rich compositions relative to tourmalines in sulfide free assemblages from the same area suggesting early premetamorphic introduction of boron and mg enrichment of tourmaline by sulfide silicate reactions during metamorphism combined field and geochemical data indicate that the district tourmalinites represent normal clastic sediments that were metasomatically altered by boron rich hydrothermal fluids at or below the sediment water interface whole rock chemical analyses of 33 tourmaline rich rocks show linear trends of data for major and trace elements that closely resemble the trends observed for unmineralized elastic metasedimentary rocks of the district average fe al mg al na al and ti al molar ratios of the tourmaline rich rocks and clastic metasediments are very similar the average k al molar ratio of the tourmaline rich rocks is significantly lower than that of the clastic metasediments reflecting the loss of k during tourmalinite formation chondrite normalized patterns of rare earth elements ree in the quartz rich tourmalinites are generally similar to those of the clastic metasediments except for minor depletions of light ree local positive and negative ce anomalies suggest tourmalinite formation in the presence of seawater or a seawater derived pore fluid the geochemical data imply relative immobility of al ti cr and heavy ree during hydrothermal alteration and later metamorphism boron isotope analyses of 52 tourmaline separates show a total range of delta 11 b values from 26 8 to 17 0 per mil fine grained euhedral nonpoikilitic tourmalines from tourmalinites in the andalusite muscovite zone in the northern part of the district e g black prince mine have delta 11 b values from 21 to 17 per mil whereas coarse granoblastic and poikilo blastic tourmalines from the sillimanite and two pyroxene granulite zones in the southern part of the district e g globe mine have delta 11 b values of 24 to 19 per mil tourmalines in strongly retrogressed tourmalinites have delta 11 b values from about 27 to 20 per mil the observed variations in delta 11 b are consistent with prograde and retrograde metamorphic fractionation of boron isotopes in which the fluid phase is preferentially enriched in the heavier isotope 11 b premetamorphic hydrothermal fluids that deposited the black prince tourmalinites had delta 11 b values of 8 to 5 per mil at 200 degrees to 300 degrees c suggesting a boron source from nonmarine evaporite borates tourmalinites in the broken hill district apparently formed by the same submarine hydrothermal processes as the main pb zn ag lodes and the siliceous ferromanganese protoliths of the garnet quartzites in our model the hydrothermal system s acquired abundant boron by leaching evaporitic borates within the thackaringa group the stratigraphic sequence that underlies the broken hill group and most of the tourmaline concentrations we suggest that evaporites of the thackaringa group provided a source of readily extractable boron for formation of the tourmalinites and also the source of the fluoride sulfur and perhaps the carbonate in the main lodes such evaporites may have been critical for increased metal chloride complexing and transport necessary for deposition of the high grade pb zn ag ores the broken hill deposit may have formed contemporaneously with the mount isa and mcarthur river pb zn ag deposits in similar evaporite bearing sequences during widespread early proterozoic continental rifting

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

archean inheritance in zircon from late paleozoic granites from the avalon zone of southeastern new england an african connection abstract in southeastern new england the narragansett pier granite locally intrudes carboniferous metasedimentary rocks of the narragansett basin and yields a monazite u pb permian emplacement age of 273 2ma zircon from the narragansett pier granite contains a minor but detectable amount of an older inherited component and shows modern loss of lead zircon from the late stage aplitic westerly granite exhibits a more pronounced lead inheritance permitting the inherited component to be identified as late archean such old relict zircon has not been previously recognized in proterozoic to paleozoic igneous rocks in new england and may be restricted to late paleozoic rocks of the avalon zone we suggest that the archean crustal component reflects an african connection in which old archean crust was underplated to the avalon zone microplate in the late paleozoic during collision of gondwanaland with avalonia

a review of the middle late pennsylvanian west european regional substages and floral biozones and their correlation to the geological time scale based on new u pb ages abstract lower moscovian duckmantian to lower asselian ash beds in the continental basins of the central and western czech republic have yielded 15 new high precision u pb single crystal zircon ca id tims ages these are used to improve the calibration of the west european regional terrestrial stages and their correlation to the geological time scale they also allow an improved correlation between the macrofloral biozones that are used for biostratigraphy in the european pennsylvanian coalfields the marine biozones on which the global geological time scale was partly established and the fresh water and terrestrial faunal biozones most of the floral biozones have proved to be essentially isochronous although the ranges of some individual but stratigraphically important taxa may differ between basins

late permian non marine marine transitional profiles in the central southern permian basin northern germany the transition from rotliegend to zechstein within the southern permian basin is one from continental desert to a marine environment during the upper rotliegend ii a huge playa lake existed there this lake was temporarily influenced by precursors of the zechstein transgression therefore the mega playa evolved into a sabkha system one of these early marine ingressions is known from an outcrop in schleswig holstein laminated silt and claystones deposited within a standing water body are intercalated in siltstones of a salt flat environment the lake sediments are characterised by high frequency cyclicity shown by the sedimentary record and also by palaeontological data the section contains fresh water as well as brackish marine and marine fauna climatically forced cycles interact with marine incursions after the zechstein transgression had flooded the basin completely sedimentation was controlled by sea level fluctuations two sections in the southern north sea and in schleswig holstein are presented in this paper cyclicities with different frequencies controlled the sedimentation of the kupferschiefer t1 and the werra carbonate ca1 sediments of the north sea sequence were deposited within a shallow bay at the margin of an elevation therefore the high frequency cyclicity became obvious within the sedimentary patterns and in the faunal content

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

structural implications of some radiometric ages of igneous rocks in southeastern new england u th pb zircon rb sr whole rock and k ar hornblende isotopic ages reveal two major episodes of igneous activity in southeastern new england one in late proterozoic z time 600 650 m y ago and the other in devonian to ordovician time 375 450 m y ago the dated rocks are discussed in the context of several individual structural provinces that evolved more or less independently of each other prior to middle to late paleozoic assembly these provinces generally are bounded by major faults and or abrupt changes in metamorphic grade and from east to west include i the milford dedham zone ii the putnam nashoba zone iii the merrimack synclinorium and iv the bronson hill zone from the present and other recently published studies reasonably accurate ages representative of the two major episodes can now be assigned to many of the igneous rocks other units remain less well constrained but probably may be placed into one or the other of the general age groupings case by case examination of the geochronologic data makes us cautious in accepting some apparent fine structure age resolution within each grouping until factors such as inherited zircon and metamorphic overprinting can be better evaluated with the above mentioned qualifications in mind igneous rock ages summarized according to structural province are as follows i milford dedham zone a late proterozoic z dedham granite and related rocks 630 15 m y 595 15 m y 612 646 m y milford granite 630 15 m y 591 50 m y hope valley alaskite gneiss and scituate granite gneiss ages uncertain unnamed granite near assonet 600 650 m y b devonian to ordovician alkalic rocks including quincy cape ann and peabody granites wenham monzonite and nahant gabbro ii putnam nashoba zone a late proterozoic z no plutonic rocks identified but may include some metavolcanic rocks b devonian to ordovician sharpners pond diorite 430 5 m y andover granite 408 22 m y 450 22 m y muscovite granite near west berlin age uncertain preston gabbro 424 5 m y ill merrimack synclinorium a late proterozoic z granitic orthogneiss unit of the massabesic gneiss complex 600 620 m y metavolcanic unit of the massabesic gneiss complex 646 m y or older b devonian to ordovician fitchburg complex at maiden hill 402 11 m y fitchburg complex at rollstone quarry 390 15 m y newburyport complex 450 15 m y ayer granite 433 5 m y chelmsford granite age uncertain muscovite biotite granite at millstone hill 372 7 m y canterbury gneisses 395 10 m y 392 9 m y iv bronson hill zone a late proterozoic z dry hill gneiss of the pelham dome 600 m y b devonian to ordovician monson gneiss 440 10 m y these distinctive age patterns together with contrasts in petrography and texture of the igneous rocks in stratigraphy of the country lock and in metamorphic grade accentuate the separate geologic development of each structural province no correlation involving preassembly geology should be attempted across province boundaries without due consideration of the exotic character of each province

high precision u pb zircon age calibration of the global carboniferous time scale and milankovitch band cyclicity in the donets basin eastern ukraine 1 high precision id tims u pb zircon ages for 12 interstratified tuffs and tonsteins are used to radiometrically calibrate the detailed lithostratigraphic cyclostratigraphic and biostratigraphic framework of the carboniferous donets basin of eastern europe chemical abrasion of zircons use of the internationally calibrated earthtime mixed u pb isotope dilution tracer and improved mass spectrometry guided by detailed error analysis have resulted in an age resolution of 0 05 or 100 ka for these carboniferous volcanics this precision allows the resolution of time in the milankovitch band and confirms the long standing hypothesis that individual high frequency pennsylvanian cyclothems and bundles of cyclothems into fourth order sequences are the eustatic response to orbital eccentricity 100 and 400 ka forcing tuning of the fourth order sequences in the donets basin to the long period eccentricity cycle results in a continuous age model for the middle to late pennsylvanian moscovian kasimovian ghzelian strata of the basin and their record of biological and climatic changes through the latter portion of the late paleozoic ice age detailed fusulinid and conodont zonations allow the export of this age model to sections throughout euramerica additional ages for mississippian strata provide among the first robust radiometric calibration points within this subperiod and result in variable lowering of the base ages of its constituent stages compared to recent global time scale compilations

early triassic conchostracans crustacea branchiopoda from the terrestrial permian triassic boundary sections in the moscow syncline abstract the permian triassic boundary marks the greatest mass extinction in earth s history in order to understand the real causes of this severe extinction event multidisciplinary investigations around the globe are required here the terrestrial permian triassic boundary sections in the vladimir region central russia were sampled bed by bed for conchostracan study in the early triassic intervals the following taxa were recognized for the first time cornia germari beyrich 1857 euestheria gutta lutkevitch 1937 magniestheria mangaliensis jones 1862 palaeolimnadiopsis vilujensis varentsov 1955 and rossolimnadiopsis novozhilov 1958 the wide distribution of c germari demonstrates their high value for biostratigraphy since this species was also reported from the lower buntsandstein subgroup in the germanic basin as well as from early triassic deposits in hungary greenland and siberia the assumption of an early triassic age of the studied sections is also supported by associated tupilakosaurus bone fragments which point to the tupilakosaurus wetlugensis zone in the earliest triassic

structure of the lower crust beneath the gulf of maine summary the variability of deep crustal reflections in usgs line 1a across the offshore new england appalachians shows the differing influence of paleozoic and mesozoic tectonic events mesozoic extension has not significantly modified paleozoic thrust faults penetrating the lower crust in the northern gulf of maine mesozoic extension or paleozoic crustal melting could explain the lower crustal character in the central gulf

marine ingressions into the middle late permian saline lake of the southern permian basin rotliegend northern germany possibly linked to sea level highstands in the arctic rift system abstract a huge saline lake existed in the southern permian basin spb of northwest europe during late wordian to early wuchiapingian more than 2500 m thick continental siliciclastics and evaporites of the upper rotliegend ii were deposited before the marine zechstein transgression flooded the basin marine deposition took place in the arctic rift system between east greenland and the fennoscandian shield at that time interval sediments of the foldvik creek group reflect relative sea level fluctuations short termed pre zechstein ingressions from the boreal realm into the spb are known by the marine lamellibranch liebea reichei however sedimentological analysis of different saline lake horizons show that the marine influenced saline lake horizon does not differ lithologically from other saline lake claystone layers in the rotliegend succession the 87 sr 86 sr ratios of anhydrite 0 7089 0 7100 reflect deposition in a continental setting in contrast to this s isotopic values more than 11 7 cdt reflect marine pre zechstein ingressions into the spb in the middle niendorf and munster members s isotopic values of anhydrite can be used as an indicator for marine influence in the spb the pre zechstein ingressions superimpose the climatic triggered lake level fluctuations of the rotliegend saline lake two marine ingressions can be integrated into a set of regularly recurring abnormities in the depositional evolution these important evolutionary steps the saline lake formation the garlstorf ingression the p ameland and bahnsen lake level highstands the niendorf ingression and the zechstein transgression show a periodicity of more or less 1 ma one million year cyclicity is also known from deposits of the arctic rift system in east greenland wegener halvo and ravnefjeld formations a correlation of the upper rotliegend ii deposits with the succession of east greenland is proposed based on the assumption that the marine ingressions as well as the exceptionally intensive saline lake expansions could be linked to sea level highstands in the arctic rift system the result is the first correlation of upper rotliegend ii deposits with marine strata

a shear zone origin for alleghanian permian multiple deformation in eastern massachusetts the area around worcester massachusetts has been used to determine which deformational and metamorphic features are due to the alleghanian permian orogeny and which are pre alleghanian isolated fault bounded inliers of carboniferous rocks display evidence of a single metamorphism and the formation of two prominent cleavages the first cleavage formed synchronously with metamorphism pre carboniferous metasedimentary rocks have been affected by two metamorphisms and contain three prominent cleavages the initial cleavage formed during the first metamorphism and the second cleavage formed during the second retrogressive metamorphism thus the second two cleavages and the second metamorphism in pre carboniferous rocks are interpreted as alleghanian normal displacements on two distinct faults are bracketed by the formation of the first and second alleghanian cleavages the initial faulting along the newly defined wachusett mylonite zone wmz formed a wide zone of ductile mylonites which dips moderately to the northwest and contains elongation lineations which trend northwest the second faulting along the clinton newbury fault cnf occurred along a steeply inclined plane which cuts the wmz mylonites and contains a thin zone of phyllonites and mylonites which have elongation lineations which trend west alleghanian cleavages and metamorphism are confined to a mappable zone which is approximately 15 km wide where well defined this zone is interpreted as a ductile shear zone which moved twice forming the first and second alleghanian cleavages early formed pre alleghanian metamorphic minerals are retrograded to hydrous phyllosilicates and new hydrous minerals formed in the shear zone indicating that it was a pathway for fluid flow the initial motion was left lateral with a thrust component the second cleavage formed during top to the northwest normal displacements thus the history of alleghanian tectonism in this area began with sinistral faulting and then included three displacements along normal faults or shear zones this suggests that the strain history included two distinct episodes with the second experiencing slightly different strain orientations at different times resulting in first wmz normal motion then cnf normal motion and finally normal displacements related to the second alleghanian cleavages this history agrees well with other work on the nature of the alleghanian orogeny in the northeast united states

conchostracans in continental deposits of the zechstein buntsandstein transition in central germany taxonomy and biostratigraphic implications for the position of the permian triassic boundary within the zechstein group abstract the end permian mass extinction marks the largest biotic crisis in the geologic record the stratigraphic position of this boundary in continental deposits is still under discussion in the present study conchostracans from the zechstein buntsandstein late permian to early triassic transition in central germany have been taxonomically reinvestigated in order to better understand their utility for fine scale biostratigraphy in continental permian triassic boundary sections the studied material was obtained from both collections and recent sampling activities in classical key sections and new outcrops of the zechstein and buntsandstein groups the sedimentary environments of the conchostracan occurrences are interpreted as lacustrine to fluvial facies depending on the paleogeographic position within the basin of the respective sections the conchostracan fauna in the zechstein buntsandstein transition consists of euestheria gutta palaeolimnadiopsis vilujensis cornia germari estheriella marginostriata estheriella costata estheriella nodosocostata magniestheria mangaliensis and euestheria nordvikensis based on comparison with the early triassic conchostracan record in the moscow syncline the palaeolimnadiopsis vilujensis euestheria gutta association in the upper part of the fulda formation indicates both its early triassic age and a position of the continental permian triassic boundary within the zechstein group

an image mapping approach to u pb la icp ms carbonate dating and applications to direct dating of carbonate sedimentation we present a new approach to laser ablation inductively coupled plasma mass spectrometry la icp ms u pb dating of carbonates based on selection and pooling of pixels from 2 d elemental and isotopic ratio maps this image mapping technique is particularly useful for targeting subdomains in samples with complex geological histories key major and trace elements that are sensitive to detrital components postformational fluid ingress mineralogical changes or diagenetic overprinting are measured along with the pb and u isotopic data laser sampling is undertaken along successive linear rasters that are compiled into maps using the monocle add on for iolite with one pixel in the map corresponding to one time slice of the time resolved signal these element element ratio and isotope ratio maps can be overlain over photomicrographs or scanning electron microscopy images to spatially link compositional data to textural and structural features the pixels corresponding to likely homogeneous age domains can be isolated by applying appropriate selection criteria e g th 0 3 ppm mg ca 0 004 and pooled into pseudo analyses using a proxy for the parent daughter ratio e g 207pb 235u 238u 208pb to retrieve the largest possible spread of the data points on isochron diagrams the approach is best suited for analytical setups capable of rapidly or simultaneously scanning over a large mass range and can yield a precision of 1 or better on quadrupole instruments depending on u concentration 238u 204pb and age of the sample the sample specific filtering criteria for selection and rejection of data and their rationale can be reported resulting in more transparency with regard to data processing

the biostratigraphic importance of conchostracans in the continental triassic of the northern hemisphere conchostracans or clam shrimp order conchostraca sars are arthropods with a carapace consisting of two chitinous lateral valves triassic conchostracans range in size from 2 to 12 5 mm long and are common in deposits that formed in fresh water lakes isolated ponds and brackish areas their dessication and freeze resistant eggs can be dispersed by wind over long distances therefore many conchostracan species are distributed throughout the entire north ern hemisphere in the late permian to middle triassic interval several of these forms are also found in gondwana many wide ranging conchostracan species have short stratigraphic ranges making them excellent guide forms for subdivision of triassic time and for long range correlations the stratigraphic resolution that can be achieved with conchostracan zones is often as high as for ammonoid and conodont zones found in pelagic marine deposits this makes con chostracans the most useful group available for biostratigraphic subdivision and correlation in continental lake deposits upper triassic gondwanan conchostracan faunas are different from conchostracan faunas of the northern hemisphere in the norian some slight provincialism can be observed even within the northern hemisphere for example the sevatian redondestheria seems to be restricted to north america and acadiestheriella n gen so far has been found only in the sevatian deposits from the fundy basin of southeastern canada here we establish a con chostracan zonation for the changhsingian late permian to hettangian early jurassic of the northernhemispherethat forthemostpart isverywellcorrelatedwiththemarinescale thiszona tion is especially robust for the changhsingian to early anisian late ladinian to cordevolian and rhaetian to hettangian intervals for most of the middle and upper triassic this zonation is still preliminary five new genera six new species and a new subspecies of conchostracans are described that are stratigraphically important half of the eight stage boundaries of the triassic have been defined by a bio event within a marine global stratotype and point gssp locality and these definitions have been accepted by both the international subcommission on triassic stratigra phy and the international commission on stratigra phy the remaining four stage boundaries are nearing final definition in the lower triassic both the base of the induan priority brahmanian stage base of triassic and the base of the next younger olenekian stage have been firmly defined in the middle triassic there is wide agree ment that the defining species for the base of the anisian stage should be chiosella timorensis in the gssp candidate site at desli caira romania but there has not yet been a formal vote on this the base of the overlying ladinian stage however has been firmly defined in the upper triassic the base of the carnian has been firmly likewise defined but there is not yet a final defi nition for the boundaries of the overlying norian and rhaetian stages a consensus has not been reached on a defining species for the base of the norian or its gssp locality but all of the different proposals under consideration do at least fall within a rather narrow stratigraphic interval for the base of the rhaetian misikella posthernsteini kozur mock has been chosen as the defining species by the international working group on the rhaetian stage and the gssp candidate locality at steinbergkogel austria has been studied in detail by a group under the leadership of l krystyn vienna and presented to the participants of the international conference on upper triassic sub divisions zonations and events in bad goisern in the autumn of 2008 the base of the overlying hettangian stage base of the jurassic has been defined so far only by a working group as the fad first appearance datum of psiloceras spelae guex taylor rakus bucher the final definition of the triassic stages within marine gssp sections will be completed in the near future but more than 50 of known triassic rocks are of continental origin therefore the main task of triassic stratigraphers in thefuture will besubdivid ing and correlating terrestrial strata both between

applications of single grain zircon evaporation analyses to detrital grain studies and age discrimination in igneous suites abstract 207 pb 206 pb ages determined by evaporation of single zircon grains from rocks of the new england appalachians in the usa permit an assessment of the applicability of this method to rocks that have been strongly disturbed by orogenesis tests conducted on highly metamorphosed and deformed orthogneisses of known protolith age whose u pb upper intercept zircon ages obtained through isotope dilution methods show profound post crystallization discordance demonstrate that the evaporation method is successful in recovering protolith ages uncertainties are 10 15 my for rocks of paleozoic age or older preliminary results suggest that the method is particularly useful for provenance studies of sedimentary rocks and in the discrimination among groups of rocks that are known to differ in age but are otherwise difficult to separate on the basis of field or petrographic characteristics 207 pb 206 pb ages of detrital zircon grains from two metasedimentary units from opposite sides of the new england appalachians reveal the distinct provenances of these rocks the missisquoi formation in southeastern vermont usa is comprised in part of detritus derived from the 1 0 1 2 ga grenvillian province of laurentia whereas this component is conspicuously absent from the plainfield formation in easternmost connecticut the detrital zircon age data suggest that the missisquoi formation accumulated peripheral to the laurentian craton during the early paleozoic whereas the plainfield formation detritus was supplied by non laurentian ossibly west african sources during the late proterozoic or early paleozoic in southern vermont the evaporation method successfully distinguishes between two groups of augen gneisses with ages of 960 ma and 1120 ma which were first recognized through isotope dilution methods collectively these results indicate that the dating of single zircon grains by the evaporation method can be widely exploited in the study of complexly deformed and strongly metamorphosed rocks

u pb zircon geochronology of roxbury conglomerate boston basin massachusetts tectono stratigraphic implications for avalonia in and beyond se new england high precision ca tims 206pb 238u zircon dates from sandstone and brighton igneous rocks associated with roxbury conglomerate in the boston basin eastern massachusetts provide constraints on the age and tectonic significance of these deposits detrital zircon suites from roxbury related sandstones representing in ascending order the franklin park member proposed name the brookline member and the squantum member establish closely comparable maximum depositional ages of 595 14 0 90 598 87 0 71 and 596 39 0 79 ma respectively the youngest of these is the best maximum age estimate of the conglomerate brighton dacite near the base of the brookline member and amygdaloidal andesite near the top yield respective crystallization ages of 584 19 0 70 ma and 585 37 0 72 ma these virtually identical dates support previous interpretations of these particular units as shallow intrusions and thus represent minimum ages of associated conglomerate the roxbury brighton sequence is traditionally shown as inter fingering northward with 570 ma mudstone of the cambridge argillite but the age range of the conglomerate makes this impossible conglomerate lacking quartzite clasts typical of the roxbury proper and associated with 593 19 0 73 ma rhyolite on the south side of the basin is re assigned to the lynn mattapan volcanic complex which rests unconformably on dedham granite in basement exposed west and north of the basin as well calc alkaline geochemistry and ages of the 609 to 584 ma dedham lynn mattapan brighton assemblage link it with 630 to 580 ma arc sequences in other northern appalachian avalonian terranes roxbury conglomerate accumulated in fault bounded intra arc basins near the end of this magmatic cycle

permian climate development in the northern peri tethys area the lodeve basin french massif central compared in a european and global context abstract the lodeve basin which contains an exceptional long and nearly uninterrupted profile of early to late permian continental red beds is well correlated to the other european permocarboniferous basins together they cover the time span from the late pennsylvanian to the permian triassic boundary although these basins were placed within the equatorial belt for the whole permian several climatic changes are recorded in the sediments terrestrial sedimentation is governed by the interaction of climate and tectonics as well as by volcanism to a variable degree therefore small scale climatic variations of the milankovitch band are hardly discernable and if so they could not be correlated between different basins indeed larger scale climatic shifts could be identified it is shown that the shift from the carboniferous icehouse to the mesozoic warmhouse was a multi stage process this global warming resulted in a general aridisation of northern pangea indicated by outspreading playa and sabkha red beds aeolianites and evaporites several short phases of increased humidity interrupted this trend indicated by wet red beds lake sediments and coal deposits in central and southern europe these wet periods are traceable within the late stephanian lower rotliegend gzhelian asselian topmost lower rotliegend asselian sakmarian upper rotliegend i late artinskian early kungurian and upper rotliegend ii zechstein wuchiapingian the aridisation of the northern pangea which accelerated near the sakmarian artinskian transition is attributed to a reorganisation of the major ocean currents cold water currents along the western flank of the pangea indicated by the permian chert event blocks moisture transport from west onto the continent during roadian and wordian the onset of an additional cold water current along the cimmerian continents blocks moisture transport from the east both phenomena together are responsible for the maximum of aridity at the early to middle permian transition additionally the equatorial climate has been affected by an increasing seasonality within the late pennsylvanian and permian caused by the wide shifting of the zone of inter tropical convergence itc over the equator based on a new reconstruction of the pangean assembly in this paper climatic changes in the permian are interpreted and causes of the arid humid arid shifts are examined phases of higher humidity are often related to events of global impact like the waxing and waning of the gondwanan glaciation obtained in the south african karoo basin dwyka group but also regional events had strong climatic influence the zechstein transgression in the northern and southern permian basin as well as the bellerophon transgression of the southern alps caused the wet phase in the wuchiapingian

the early permian age of the dunkard group appalachian basin u s a based on spiloblattinid insect biostratigraphy abstract the dunkard group of the appalachian basin ohio pennsylvania west virginia is a 340 m thick sequence of primarily fluvial and lacustrine deposits that contain a diverse fossil record including a blattoid insect forewing identified as sysciophlebia balteata scudder this wing originates from the cassville shale in the waynesburg formation at the very base of the dunkard group s balteata is a zone species of a late paleozoic spiloblattinid insect zonation that is calibrated by the co occurrence of spiloblattinid zone species with conodont and fusulinid zone species in kasimovian to early asselian mixed marine continental profiles of new mexico usa and the donets basin in the ukraine as well as by the isotopic ages of volcanic intrusions into the late stephanian gzhelian strata of the saale basin in germany the base of the zone underlying the s balteata zone is defined by the fad of sysciophlebia ilfeldensis in the late gzhelian and has an upper limit lad of early to middle asselian an early or middle asselian to earliest sakmarian range of both the subzones of the s balteata zone can be inferred given that the mean duration of a spiloblattinid insect zone is about 1 5 to 2 ma the upper limit of the s balteata zone is early sakmarian hence the base of the dunkard group should be maximally of early asselian or minimally of earliest sakmarian age

high precision u pb zircon ages for explosive volcanism calibrating the nw european continental autunian stratotype volcanism was intense in western european basins during the late carboniferous early permian transition related to the late variscan extension and associated magmatism in the autun basin explosive eruptions expressed as highly weathered distal ashfall deposits tonsteins were preserved in lacustrine to swamp environments the analysis of eleven tonsteins confirmed as non reworked volcanic horizons indicates a highly explosive acidic calc alkaline volcanism with active volcanic centres probably linked to massif central or vosges black forest magmatism new accurate ca id tims u pb ages are obtained from four of these tonsteins recorded within the lower autunian igornay and muse fms which defines the lower part of the autunian stratotype in the autun basin the middle part of the igornay fm is dated at 299 9 0 38 ma the lally oil shale bed is dated at 298 91 0 08 ma and the upper part of the muse oil shale bed is dated between 298 05 0 19 and 298 57 0 16 ma for the first time a numerical calibration of the regional continental autunian stage in its stratotype is proposed thus allowing correlation with global marine stages defined in the urals and highlighting a late gzhelian early asselian age for the lower autunian the tonstein in the lally oil shale appears to demarcate the carboniferous permian boundary within the 100 kyr resolution of the u pb ages in both the autun and southern uralian basins comparison with other european domains confirms that these new ages are consistent with well known macrofloral assemblages characteristic of the autunian

non marine permian biostratigraphy and biochronology an introduction the permian time scale based on marine rocks and fossils is well defined and of global utility but non marine permian biostratigraphy and chronology is in an early phase of development non marine permian strata are best known from western europe and the western united states but significant records are also known from russia south africa china and brazil global time terms based on non marine permian strata such as rotliegend zechstein autunian saxonian and thuringian are either inadequately defined or poorly characterized and should only be used as lithostratigraphic terms macro and microfloras have long been important in non marine permian correlations but are subject to limitations based on palaeoprovinciality and facies climatic controls charophytes conchostracans ostracodes and freshwater bivalves have a potential use in non marine permian biostrati graphy but are limited by their over split taxonomy and lack of well established stratigraphic distributions of low level taxa tetrapod footprints provide poor biostratigraphic resolution during the permian but tetrapod body fossils and insects provide more detailed biostrati graphic zonations especially in the lower permian numerous radioisotopic ages are available from non marine permian sections and need to be more precisely correlated to the global time scale the middle permian illawarra reversal and subsequent magnetic polarity shifts are also of value to correlation there needs to be a concerted effort to develop non marine permian biostratigraphy to correlate it to radio isotopic and magnetostratigraphic data and to cross correlate it to the marine time scale

earliest record of exophytic insect oviposition on plant material from the latest pennsylvanian gzhelian stephanian c of the saale basin germany abstract the late palaeozoic fossil record of plant insect interactions contains few records of oviposition here we report the earliest evidence of exophytic oviposition where eggs are laid directly on the outer surface of plants the fossil structures consist of small circular impressions on plant fossils from the late pennsylvanian gzhelian stephanian c of the saale basin in germany their interpretation as exophytic insect eggs is supported by the oviposition pattern their three dimensional preservation and the undamaged nature of the plant host tissue the tight arrangement of the eggs in curved arcs suggests a producer with a short abdomen such as roachoids the ancestral group of the dictyoptera sensu stricto a diagnostic feature of roachoids is their long ovipositor which was well suited for deposition of single eggs in a distinct pattern