spatangoid produced ichnofabrics bateig limestone miocene spain and the preservation of spatangoid trace fossils a spatangoid produced ichnofabric is described from the miocene bateig limestone se spain this ichnofabric is characterized by the dominant presence of large meniscate burrows bichordites produced by irregular echinoids this constitutes an unusual mode of occurrence for spatangoid bioturbation as their traces are most typically preserved in bases and tops of sandstone event beds in fact despite their important role as burrowers in modern settings that can be extended back to the early cretaceous based on their body fossil record spatangoid trace fossils scolicia and bichordites are comparatively rare several factors play an important role in their preservation mechanism of burrowing sediment characteristics early diagenesis and presence absence of deep tier burrowers spatangoid produced ichnofabrics such as those from the bateig limestone characterize depositional settings with intermittent deposition of event beds where there is an absence of deeper tier bioturbation

deep sea bivalvian highways an ethological interpretation of branched protovirgularia of the palaeogene muroto hanto group southwestern japan abstract well preserved specimens of the trace fossil protovirgularia occur in deep sea trough fills of the palaeogene accretionary complex of the muroto hanto group in southwestern japan the trace fossil occurring characteristically on the sole of sandstones of turbidite systems is interpreted as an interstratal trail of a protobranch bivalve having a cleft foot among the muroto hanto protovirgularia many specimens of branched variants have been found based on the morphological analyses coupled with knowledge of the behaviour of the modern intertidal molluscs the branched specimens are interpreted to have formed as the result of interstratal trail following behaviour of the infaunal protobranchs the animals probably followed trails of other individuals in order to save energy for locomotion the incipient protovirgularia was thus interpreted to have functioned as a highway for the infaunal mollusc this is probably the first report of a trail following behaviour of infaunal invertebrates

ichnology of the late carboniferous hoyada verde formation of western argentina exploring postglacial shallow marine ecosystems of gondwana abstract the postglacial interval of the upper carboniferous hoyada verde formation of western argentina contains an ichnofauna dominated by psammichnites plummeri and psammichnites implexus with minor occurrences of ptychoplasma vagans treptichnus bifurcus lingulichnus verticalis protovirgularia isp lockeia isp palaeophycus isp scarce arthropod trackways and some bilobate structures the particular features of this association indicate a depauperate expression of the cruziana ichnofacies and suggest a context that differs from the expected in normal shallow marine settings i e archetypal cruziana ichnofacies integration of sedimentologic ichnologic sequence stratigraphic and paleontologic data points to a prograding deltaic system influenced by wave action trace fossils have been extensively used to recognize stressed brackish water environments in the late paleozoic of gondwana however the recognition of stressed settings needs to take into consideration the specific paleogeographic context of glacially influenced gondwanan settings a postglacial open sea adjacent to a paleotopographic high is considered as a possible scenario for the hoyada verde formation in this particular setting coastal biotas could have been influenced to some degree by the salinity gradient triggered by freshwater release near to melting ice masses stored in highlands and also by freshwater plumes due to longshore currents regional factors e g proximity to highlands and climate may have played an important role in controlling the characteristics of gondwanan ichnofaunas this suggests that the distinction between normal marine and brackish water settings in glacially influenced environments using trace fossils may not be as straightforward as in non glacial settings

ichnodiversity and ichnoabundance revealing depositional trends in a confined turbidite system ichnological studies are still in their infancy when it comes to the interpretation of deep marine deposits the eocene oligocene turbidite system of the gres d annot formation in south east france is well studied sedimentologically but its trace fossil content is poorly known here an integrated ichnological sedimentological study is presented from the annot sub basin for the first time which demonstrates its value for interpreting proximal to distal and axial to marginal trends in confined turbidite systems a comprehensive trace fossil data set was collected from seven outcrops situated in the southern part of the basin these data are presented following a morphology based classification scheme to allow easy recognition and characterization of ichnotaxa ichnodiversity and the abundance of ichnotaxa are regarded as important parameters in such interpretations instead of simply counting ichnotaxa per outcrop or stratigraphic unit an equation has been developed in which the ichnoabundance new term of each counted ichnotaxon is calculated an exponential growth factor is applied to the increase of the frequency of trace fossils and is assumed in this equation to better reflect the population dynamics of benthic organisms a comparison of the solution for pre turbidite and post turbidite trace fossil suites seems to be more suitable for revealing regional and stratigraphic trends compared with conventional approaches despite varying size and conditions of the studied outcrops the results achieved from the gres d annot formation can help in the reconstruction of sedimentary processes acting in this confined turbidite basin

pyrite framboids interpreted as microbial colonies within the permian zoophycos spreiten from southeastern australia two types of pyrite framboids pf probably sulphate reducing bacteria have been found within the zoophycos spreiten hosted in the guadalupian middle permian glaciomarine greywacke of the westley park sandstone member within the broughton formation from the southern sydney basin of southeastern australia they are composed of non sheathed pf1 and sheathed pf2 sub micron balls respectively chemically the sub micron balls consist of iron sulphur carbon and oxygen both pf1 and pf2 occur in rhythmic alternation within the thick light grey and thin dark grey minor lamellae of zoophycos spreiten the framboids from the minor lamellae are highly abundant and occur in an orderly arrangement of equal density and in a good state of preservation within zoophycos spreiten no homogeneous filling fecal pellets or any sign of re exploitation of the minor lamellae have been recognized no similar framboids have been observed outside zoophycos spreiten therefore the framboids are interpreted as the pyritized remains of microbial colonies within zoophycos spreiten the trace zoophycos would be a multifunctional garden that may have been carefully constructed by the zoophycos maker where different microbial colonies were orderly and carefully planted and cultured within different minor lamellae further it is proposed that the zoophycos maker had a symbiotic relationship with microbial colonies on the mutual basis of food supply and redox conditions the fact that the overlying spreiten cut the underlying ones indicates that the zoophycos from the study area is of an upward construction the rhythmic alternation of both the thick light grey and thin dark grey minor lamellae within zoophycos spreiten may be suggestive of a gardening manner of the zoophycos maker responding to the warm and cold changes food supply in pulses and variations of sedimentation rate for planting and culturing microbial colonies under the conditions of a glaciomarine environment at the high latitudes

the marine permian of east and northeast asia an overview of biostratigraphy palaeobiogeography and palaeogeographical implications abstract the permian marine biostratigraphy faunal successions and mutual correlations where possible throughout east and northeast asia are synthesized region by region based on both published literature and the author s field observations in certain parts of the region the correlation of the permian marine successions of ne asia with the permian international timescale and in particular with gondwanan permian marine sequences remains a major challenge due to profound marine provincialism during the permian however by employing biogeographically mixed faunas from east asia se mongolia ne china south primorye of far east russia and the south kitakami terrane of japan as biostratigraphic gateways coupled with some bipolarly and bi temperately shared permian marine taxa and faunas it has been possible to correlate with reasonable confidence some of the high palaeolatitude permian marine rock units and faunas of ne asia with those of the tethyan region and gondwana palaeobiogeographically the permian marine faunas of east and ne asia are assigned to four major provinces verkolyman sino mongolian japanese cathaysian and panthalassan provinces on the basis of their palaeogeographical distribution patterns and characteristics of faunal assemblages of these the sino mongolian japanese province has considerable significance for regional palaeogeographical plate tectonic and palaeoceanographical reconstructions during the middle permian because of its conspicuously mixed cool and warm water marine biota the origin of this biogeographically mixed marine biota is interpreted to have resulted from a combination of some key factors including the increased tectonic convergence between the bureya jiamusi terrane and the sino korean platform during the permian and the intermingling of both warm and cold water ocean currents off the eastern coastal areas of the bureya jiamusi terrane and the sino korean platform during the middle permian

proximal distal ichnofabric changes in a siliciclastic shelf early pliocene guadalquivir basin southwest spain abstract the lower pliocene deposits cropping out along the atlantic coast of cadiz in the conil cabo roche area formed on a shelf gently deepening towards the w nw up to five types of facies can be recognized distributed in belts from proximal to distal parts of the shelf 1 coarse grained sandstone with trough cross stratification facies on the most proximal parts of the shelf inner shelf deposits 2 medium grained sandstone with low angle planar cross stratification facies deposited in a more distal position due to storm currents transporting sediment offshore this facies intercalates with the previous trough cross bedded sandstone 3 massive fine grained sandstone and siltstone facies laterally and vertically related with the previous facies type and representing sediments formed in the middle shelf close to the storm wave base 4 tabular sandstone bed facies corresponding to storm bed deposits intercalated within the two previous facies 5 greenish bluish shale facies accumulated on the outer shelf below storm wave base three ichnofabrics associated with these facies are recognized 1 the two cross bedded facies are dominated by a macaronichnus ichnofabric characterized by macaronichnus and bichordites traces that represent colonization of a shifting sandy substrate by polychaetes macaronichnus tracemakers and by sea urchins bichordites producers 2 a rosselia ichnofabric consisting of vertical traces of rosselia cross cutting macaronichnus characterizes the interval of massive fine grained sandstone and silt facies and interbedded tabular sandstones this ichnofabric formed under high sedimentation rates with rosselia traces exhibiting stacked patterns that indicate vertical readjustment following deposition 3 massive fine grained sandstone and silt facies are distinguished by a cylindrichnus ichnofabric this fabric was produced by the activity of a moderately diverse community dominated by sessile burrow dwelling probably superficial detritus feeding polychaetes rosselia and cylindrichnus tracemakers and vagile deposit feeding polychaetes planolites producers in addition infaunal deposit detritus feeders producing spreiten structures teichichnus are found in distal areas pervasive indistinct mottling of the sediment of this facies was probably due to the activity of very shallow burrowers in the uppermost sediment tiers this proximal distal replacement of ichnofabrics reflects the change of benthic communities across the shelf this distribution does not fit the traditional seilacherian ichnofacies model for soft ground shallow marine settings in which proximal vertical dwelling burrows of the skolithos ichnofacies dominate high energy environments in the pliocene of cadiz shallow tier burrows of deposit detritus feeders characterize the high energy facies instead which fit better with the cruziana ichnofacies this deviation can be related with the particular palaeoenvironmental conditions thus vagile opportunistic deposit feeders colonized the dune foreset when the dunes were stable and the progradation of the structure favored the preservation of the traces

the nature of the proterozoic cambrian transition in the northern amadeus basin central australia abstract the nature and completeness of the rock record is vital in determining whether evolution across the proterozoic cambrian boundary was episodic or explosive this study documents the nature of the neoproterozoic cambrian transition within the arumbera sandstone of the northern amadeus basin central australia and demonstrates an erosional surface close to this major stratigraphic boundary we are not able to recognise major facies differences between the largely unfossiliferous lower units i and ii and the rich trace fossil bearing beds of units iii iv horizons above and below the purported neoproterozoic cambrian transition were traced laterally and searched for both trace and body fossils in an attempt to locate a local boundary between the neoproterozoic and cambrian a single nonconformity bound sedimentary cycle above the major erosional surface dividing arumbera ii and iii is recognised the lowest sedimentary cycle of arumbera iii is devoid of trace fossils but at correlative levels in the ooraminna sub basin this horizon bears elements of the ediacara fauna reported for the first time herein we therefore suggest that contrary to previous studies the neoproterozoic cambrian transition is not coincident with the widespread seismic reflector but in areas of more complete sedimentation actually lies above it this study also presents new stratigraphic ichnological and palaeontological information from the neoproterozoic cambrian transition in central australia identifies areas of potentially continuous sedimentation and provides a basis for correlation of the arumbera sandstone with other neoproterozoic cambrian successions within australia and beyond

palaeoenvironmental and palaeogeographical implications of modern macaronichnus segregatis like traces in foreshore sediments on the pacific coast of central japan traces produced by modern animals provide useful information for our understanding of comparable trace fossils this paper reports on a polychaete worm euzonus producing traces which fall within the definition of the ichnotaxon macaronichnus segregatis observation on the wave dominated pacific sandy coast of central japan revealed that this animal and its trace occur exclusively in sediments of the mid foreshore portion of the beach owing to such a limited occurrence of the modern trace the ichnofossil m segregatis might be useful as an indicator of mid foreshore environment the longer axes of modern m segregatis like traces on a bedding plane are arranged perpendicular to the shoreline and accordingly its fossil counterpart can be utilized for reconstructions of the ancient shoreline orientation in support of this assumption a similar mode of m segregatis occurrence is reported from pleistocene shallow marine deposits in japan

co occurrence patterns of ice rafted dropstones and brachiopods in the middle permian wandrawandian siltstone of the southern sydney basin southeastern australia and palaeoecological implications the ecological significance of ice rafted dropstones in present day glacial marine benthic environments has received considerable attention from ecologists but similar studies based on the geological records of dropstones and associated fossils are rare in this study we report statistically significant co occurrences of ice rafted dropstones with brachiopod shells in multiple stratigraphic horizons at multiple sites from the middle permian wandrawandian siltstone of the southern sydney basin in southeastern australia we analysed the distribution patterns of both dropstones and brachiopod dominated fossil assemblages by using a quadrat based sampling method and spatial point pattern analysis it was revealed that the co occurrences of ice rafted dropstones and brachiopod shells are not random rather they demonstrate statistically significant and stratigraphically recurring associations that are here interpreted to represent dropstone associated brachiopod dominated palaeoecological communities in these recurring palaeocommunities the presence of ice rafted dropstones is considered to have added habitat complexity and heterogeneity to the benthic environment especially suited to the settlement of brachiopods in addition the sinking of dropstones from floating ice masses through the water column to the silty seafloor is interpreted to have enriched the nutrient and oxygen supply to the benthic environment further aiding the flourishing and maintenance of a diverse and stable marine benthic fauna supplementary material original data collection supplementary material 1 and spatial point pattern analysis results of rest quadrats supplementary material 2 are available at https doi org 10 6084 m9 figshare c 4101743

stratigraphic signature of the late palaeozoic ice age in the parmeener supergroup of tasmania se australia and inter regional comparisons abstract recent research in eastern australia has established that rather than being a single long lived epoch the late palaeozoic ice age comprised a series of glacial intervals each 1 8 million years in duration separated by non glacial intervals of comparable duration in order to test whether the glacial events recognized in new south wales and queensland have broader extent we conducted a reappraisal of the parmeener supergroup of tasmania southeast australia a facies analysis of the pennsylvanian to permian section was carried out allowing rationalization of the succession into four recurrent facies associations a glacigenic facies association restricted to the basal pennsylvanian earliest permian wynyard formation and correlatives b glacially cold climate influenced to open marine shelf facies association which accounts for large parts of the permian succession c deltaic facies association which specifically describes the lower permian lower freshwater sequence interval and d fluvial to estuarine facies association which specifically addresses the upper permian cygnet coal measures and correlatives indicators of sediment accumulation under glacial influence and cold climate are restricted to four discrete stratigraphic intervals all of which indicate that glaciation was temperate in nature the lowermost of these incorporating the basal wynyard formation and its correlatives and overlying woody island formation shows evidence of proximal glacial influence subglacial grounding line fan and fjordal facies and is likely a composite of one or more pennsylvanian glacial event s and an earliest permian asselian glacial the second of late sakmarian to early artinskian age comprises an initial more proximal ice influenced section and an overlying more distal ice influenced interval the third kungurian to roadian and fourth capitanian intervals are both distal glacimarine records the four intervals are of comparable age to glacials p1 p4 respectively recognized in new south wales and queensland notwithstanding apparent discrepancies of

the lower permian wasp head formation sydney basin high latitude shallow marine sedimentation following the late asselian to early sakmarian glacial event in eastern australia the lower permian wasp head formation early to middle sakmarian is a 95 m thick unit that was depos ited during the transition to a non glacial period following the late asselian to early sakmarian glacial event in eastern australia this shallow marine sandstone dominated unit can be subdivided into six facies associa tions i the marine sediment gravity flow facies association consists of breccias and conglomerates deposited in upper shoreface water depths ii upper shoreface deposits consist of cross stratified conglomeratic sand stones with an impoverished expression of the skolithos ichnofacies iii middle shoreface deposits consist of hummocky cross stratified sandstones with a trace fossil assemblage that represents the skolithos ichnofacies iv lower shoreface deposits are similar to middle shoreface deposits but contain more pervasive bioturba tion and a distal expression of the skolithos ichnofacies to a proximal expression of the cruziana ichnofacies v delta influenced lower shoreface offshore transition deposits are distinguished by sparsely bioturbated carbo naceous mudstone drapes within a variety of shoreface and offshore deposits trace fossil assemblages repre sent distal expressions of the skolithos ichnofacies to stressed proximal expressions of the cruziana ichnofacies impoverished trace fossil assemblages record variable and episodic environmental stresses possibly caused by fluctuations in sedimentation rates substrate consistencies salinity oxygen levels turbidity and other physio chemical stresses characteristic of deltaic conditions vi the offshore transition offshore facies association con sists of mudstone and admixed sandstone and mudstone with pervasive bioturbation and an archetypal to dis tal expression of the cruziana ichnofacies the lowermost 50 m of the formation consists of a single deepening upward cycle formed as the basin transitioned from glacioisostatic rebound following the asselian to early sak marian glacial to a regime dominated by regional extensional subsidence without significant glacial influence the upper 45 m of the formation can be subdivided into three shallowing upward cycles parasequences that formed in the aftermath of rapid possibly glacioeustatic rises in relative sea level or due to autocyclic progra dation patterns the shift to a parasequence dominated architecture and progressive decrease in ice rafted de bris upwards through the succession records the release from glacioisostatic rebound and amelioration of cli mate that accompanied the transition to broadly non glacial conditions

ichnology in oceanic islands case studies from the cape verde archipelago abstract miocene and pleistocene marine deposits in the cape verde archipelago are represented by a series of thin transgressive sandy bioclastic limestones that typically occur between subaerial and or submarine volcanic flows this position within volcanic flows makes them an ideal paleobathymetric case study because the submarine subaerial passage zone above them provides a reliable and independent indicator of paleodepth in terms of paleoichnology the older miocene sediments are characterized by the thalassinoides ichnoassociation whereas pleistocene sediments are characterized by the macaronichnus dactyloidites ichnoassociation the fair weather suite of the proximal cruziana ichnosubfacies is represented by the ichnotaxa dactyloidites bichordites cardioichnus phycodes teichichnus aff taenidium palaeophycus and thalassinoides in addition to the thalassinoides ichnoassociation the macaronichnus dactyloidites ichnoassociation is more complex including representatives of both the proximal cruziana and skolithos ichnofacies only representatives of the skolithos ichnofacies skolithos macaronichnus conichnus and ophiomorpha are represented in the post storm suite so far bioerosive structures were found on the miocene pleistocene unconformity surface of maio island and on basaltic paleocliffs at ponta das bicudas on santiago island they are represented by the ichnoassemblage gastrochaenolites torpedo entobia isp corresponding to the entobia ichnofacies bathymetric calibration deduced from the position of the following passage zone between submarine and sub aerial lava flow allows for confirmation of the proximal cruziana ichnosubfacies and skolithos ichnofacies at a paleodepth between 12 and 18 m depth

a new trace fossil assemblage from the middle permian broughton formation southern sydney basin southeastern australia ichnology and palaeoenvironmental significance abstract the permian triassic sedimentary succession of the southern sydney basin in southeastern australia contains a wealth of well preserved trace fossils that are important for systematic ichnological palaeoecological and palaeoenvironmental interpretations in this study a new ichnofossil assemblage comprising macaronichnus palaeophycus psammichnites protovirgularia rosselia and teichichnus is documented from the tide influenced shoreface deposit of the middle permian jamberoo sandstone member of the broughton formation two distinct ichnofabrics are recognized i the psammichnites ichnofabric characteristic of the upper middle shoreface deposit and ii the crowded rosselia ichnofabric cri representing the lower shoreface the psammichnites dominated ichnofabric is interpreted to have resulted from opportunistic behaviours of unknown trace makers whereas the cri is interpreted to represent possible strategic behaviours of stress tolerant polychaetes e g terebellid spionid and cirratulid polychaetes in a distal shoreface with high sedimentation rate thus the psammichnites crowded rosselia ichnofabric succession can be considered to represent a response to an environmental shift from proximal to distal shoreface as such this study highlights the utility of these two ichnofabrics as stressed environmental indicators

acme and demise of the late palaeozoic ice age a view from the southeastern margin of gondwana abstract palaeoenvironmental reconstructions from across the globe indicate that the climatic and oceanographic changes that accompanied the permian transition from deep icehouse to greenhouse conditions were uneven and asynchronous because of a paucity of well constrained data environmental changes in gondwana remain poorly understood relative to tropical pangaea in this regard the permian system of eastern australia provides a unique record of this transition along a high latitude open marine shelf not only was glaciation protracted here relative to other regions of gondwana but the record also spans temperate to polar palaeolatitudes providing an opportunity to examine environmental changes along a latitudinal transect we integrate proxies for 18oseawater palaeotemperature pco2 and depositional environment to assess the evolution of nearshore conditions through the permian glaciation was not continuous but rather focused into four discrete glacial epochs p1 p4 each several million years in length which alternated with nonglacial intervals of similar duration during the asselian mid artinskian p1 p2 time uniform conditions along the full extent of the margin were maintained by a cold boundary current coupled with oceanic upwelling increased spatiotemporal variability is evident at the end of glacial p2 mid artinskian perhaps due to tectonic changes that impacted the palaeogeography of the margin although glaciers had disappeared by this time elsewhere in gondwana eastern australia saw two additional periods of glaciation p3 roadian earliest captianian and p4 early wuchiagingian continued albeit intermittent glaciation was facilitated by drift toward higher palaeolatitudes orogenic activity that led to the development of areas of high elevation that could serve as nucleation points for glaciers and transient drops in atmospheric pco2 variations in meltwater input exerted a strong effect on local 18oseawater values complicating attempts to reconstruct latitudinal gradients in palaeotemperature results point to atmospheric co2 as the primary driver responsible for the dynamic climate variations evident in the record

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

restoration of cross sections through unfaulted variably strained strata data on the dip of bedding and the state of strain at specific locations within a cross section constrain the restoration of unfaulted two dimensional variably strained strata there are two major categories for restoration of such strata the first is one step restoration which involves retro deforming the strain ellipses into their corresponding unit circles while simultaneously removing dips from associated beds this procedure is appropriate if strain indicators record the transformation of the strata from the undeformed state to present deformation the second category pertains to situations in which strain indicators record the transformation of the present deformed state from an intermediate deformed state the second category requires multiple step restoration for the one step restoration procedure presented in this paper the first task is to determine the transformation constants that describe development of observed strain and bedding for each location the next task is to determine the retro deformation constants which relate points in their present deformed state to their locations in the undeformed state retro deformation constants are related to the spatial derivatives of the cartesian retro deformation displacements functions u x y and v x y for movements in the x and y directions respectively the spatial derivatives of these functions at locations of observed strain and the displacements of selected points about these sites are the basis for constructing continuous retro deformation displacements functions for the deformed section as a whole the retro deformation displacements functions are then invoked to restore the cross section this procedure is illustrated with an example cross section from the appalachian fold belt and the example shows that the section may be satisfactorily restored in this way it is just as likely however that the strain indicators for the example section are a measure of the transformation of the cross section from a prior deformed state to the present deformation accordingly multiple step restoration is required first to an intermediate less deformed state and then to the undeformed state two sets of retro deformation displacement functions are then needed i e one set for transformation to an intermediate state followed by a second to the undeformed state this procedure was done for the appalachian fold thrust belt example restoring first the present deformed section to an intermediate state derived from the regional fold history in turn intermediate state points were transformed to an undeformed state assuming knowledge of an undeformed stratal thickness and assuming that cross sectional area has been preserved this procedure is technically different to that used in the one step procedure but conceptually similar the objective once again is to discover appropriate retro deformation displacements functions

facies and allostratigraphy of high latitude glacially influenced marine strata of the early permian southern sydney basin australia the sydney basin of new south wales australia is a foreland basin containing a thick up to 10 km permo triassic succession the southern margin of the basin exposes strata deposited during late palaeozoic glaciation of south eastern gondwana the early permian wasp head pebbley beach snapper point formations and wandrawandian siltstone were deposited between 277 and 258 ma on a polar glacially influenced continental margin adjacent to ice sheets located over east antarctica and eastern australia sedimentary facies together with related ichnofacies and fauna can be grouped into six facies associations that record marine sub environments ranging from high energy storm dominated inner shelf to turbidite dominated upper slope settings cold marine conditions with near freezing bottom water temperatures are recorded by glendonites ice rafted debris most likely deposited by icebergs occurs in almost all facies associations an allostratigraphic approach emphasizing the recognition of bounding discontinuities i e erosion surfaces and marine flooding surfaces is used to subdivide the early permian stratigraphy into facies successions three types of succession can be identified and record changes in the relative influence of allocyclic controls such as basin tectonics sediment supply and glacio eustatic sea level variation together sedimentological and allostratigraphic data allow reconstruction of the depositional history of the south western margin of the sydney basin initial marine sedimentation characterized by sediment gravity flows and storm deposited sandstones of the lower wasp head formation occurred adjacent to a faulted basin margin overlying successions within the upper wasp head pebbley beach and snapper point formations record aggradation in inner to outer shelf settings along a storm and glacially influenced continental margin tectonic subsidence and basin flooding is recorded by deeper water turbidites of the wandrawandian siltstone

signatures of storms oceanic floods and forearc tectonism in marine shelf strata of the quinault formation pliocene washington usa marine shelf strata of the quinault formation reflect the influences of storm flood processes and convergent margin tectonism on sedimentation and palaeocommunity distributions in an active forearc basin of early pliocene age western washington usa the sedimentologic ichnologic and invertebrate megafaunal character of coastal sea cliff exposures in the pratt cliff duck creek area quinault indian nation reveal five different sedimentary facies scoured rosselia bioturbated mixed and acharax these facies document the shifting interplay and intensities among storms waves and river flood plumes during transgression in inner to mid shelf settings storm sedimentation on the inner shelf is recorded north of pratt cliff by amalgamated proximal tempestites of the scoured facies which grade up section to thick deposits of hummocky cross stratified sandstone indicative of strong wave influences these hummocky beds alternate in metre scale packages with banded mudstone and siltstone that have distinctive sedimentologic and ichnofaunal characteristics rosselia facies in particular the mudstone and siltstone occur as 1 15 cm thick rhythmic parallel beds that are laterally continuous internally homogeneous to faintly laminated and thus similar in nature to fine grained oceanic flood deposits reported from shelf settings offshore the modern eel river northern california the quinault flood deposits are dominated by the ubiquitous trace fossil rosselia socialis comprising vertical mud packed flaring burrows with a sand filled central shaft which has been inferred as the feeding dwelling structure of a vermiform invertebrate adapted to high sedimentation rates in inner shelf settings fairweather conditions in between the higher energy periods of storms waves and floods are recorded north of pratt cliff by the mixed facies which is interpreted as representing the sand and mud zone of the inner to mid shelf transition quieter deeper mid shelf fairweather settings are typified by the bioturbated facies south of pratt cliff where lower sedimentation rates and lower physical energies produced extensively bioturbated deposits of sandy siltstone punctuated in places by isolated sandy beds of distal tempestites quinault strata also chronicle stratigraphic signatures of subduction of the juan de fuca plate beneath western washington during the pliocene for example the imprint of geochemically unusual authigenic carbonates and a chemosynthetic palaeocommunity acharax facies have been interpreted as a methane seep on the quinault seafloor furthermore a mobile rockground epifauna of pholadid bivalves became established on abundant dark mudstone cobbles and pebbles sourced from the hoh assemblage a miocene accretionary prism that was actively deforming as well as interacting with quinault forearc sediments during the pliocene hoh mudstone clasts were supplied to the quinault shelf via seafloor piercing diapirs and eroding melange shear zones exposures of which today occur in fault contact with quinault strata along the coast from taholah to the raft river

crowded rosselia ichnofabric in the early devonian of brazil an example of strategic behavior abstract the occurrence of crowded rosselia ichnofabric in early devonian deposits of transition beds western gondwana parana basin southern brazil and the paleobiology and paleoecology of its potential tracemakers are discussed in this paper crowded rosselia ichnofabric has been recorded chiefly in cenozoic storm beds associated with high sedimentation rates on the inner shelf and is usually interpreted as resulting from opportunistic behavior of terebellid polychaetes rosselia is a common ichnotaxon in the archetypical cruziana ichnofacies developed preferentially in fair weather deposits formed in inner shelf settings during storm surges however this endobenthic community is strongly affected decimating those that are unable to escape new records presented herein reinforce the conclusion that short term colonization represented by crowded rosselia ichnofabric occurs essentially in erosive storm deposits of high sedimentation rates rather than being opportunistic the crowded rosselia ichnofabric appears to be the result of a strategic behavior developed by stress tolerant terebellid polychaetes in inner shelf zones during or just after storm surges this strategic behavior appeared during the early paleozoic and was adopted by terebellids from their earliest appearance

characteristic trace fossils in nearshore to offshore sequences upper cretaceous of east central utah more than 20 trace fossil species occur in marine facies of the cretaceous star point and blackhawk formations in the book cliffs and wasatch plateau provinces of utah major genera include ancorichnus arenicolites aulichnites chondrites conichnus cylindrichnus medousichnus ophiomorpha palaeophycus planolites rosselia schaubcylindrichnus scolicia skolithos teichichnus teredolites and thalassinoides newly named taxa include ancorichnus capronus medousichnus loculatus and rosselia chonoides most trace fossils occur in characteristic albeit intergradational ichnofacies correlative with major lithofacies of regressive nearshore to offshore sequences the latter include foreshore foreshore shoreface transition shoreface and offshore facies landward facies are typified by clean well sorted well stratified sparsely burrowed sandstones seaward facies except where interrupted by hummocky bedded sandstones exhibit successively less pure less well sorted and stratified more intensely

stratigraphic imprint of the late palaeozoic ice age in eastern australia a record of alternating glacial and nonglacial climate regime stratigraphic and sedimentological data from new south wales and queensland eastern australia indicate that the late palaeozoic ice age comprised at least eight discrete glacial intervals each 1 8 ma in duration here termed glaciations separated by nonglacial intervals of comparable duration these events spanned an interval from mid carboniferous c 327 ma to the early late permian c 260 ma and illustrate a pattern of increasing climatic austerity and increasingly widespread glacial ice from initial onset until an acme in the late early permian followed by an opposite trend towards the final demise of glaciation in the late permian the alternating glacial nonglacial motif suggests that the late palaeozoic ice age was considerably more dynamic than previously thought these patterns are remarkably consistent with recent interpretations of palaeofloral change eustatic sea level fluctuations and co 2 climate glaciation relationships for this interval of time the detailed record of alternating glacial and nonglacial climate mode disclosed herein may facilitate more closely resolved evaluations of stratigraphic records elsewhere notably in far field ice distal northern hemisphere successions

large macaronichnus in modern shoreface sediments identification of the producer the mode of formation and paleoenvironmental implications abstract the trace fossil macaronichnus segregatis is an intrastratal trail occurring in shallow marine deposits previous studies have shown that this trace fossil can be used as a powerful indicator of ancient sea level shoreline orientation beach morphodynamics and paleoceanographic conditions here we describe another type of macaronichnus an incipient large macaronichnus isp which is 5 12 mm in diameter from upper shoreface deposits of a modern sandy beach in western japan the burrow is produced by selective sand grain feeding of the opheliid polychaete travisia japonica although the detailed mechanism remains unclear based on the distribution of t japonica and other travisia species large macaronichnus isp seems to be more widely distributed across tidal flats the upper lower shoreface the continental shelf and possibly even the deep sea floor the distribution of the large burrow is quite different to that of the standard m segregatis it is therefore necessary to distinguish between the sizes of the burrows in order to use the ichnogenus macaronichnus as a paleoenvironmental indicator

convergence behavior of idealized convection resolving simulations of summertime deep moist convection over land convection resolving models crms can explicitly simulate deep convection and resolve interactions between convective updrafts they are thus increasingly used in numerous weather and climate applications however the truncation of the continuous energy cascade at scales of mathcal o 1 km poses a serious challenge as in kilometer scale simulations the size and properties of the simulated convective cells are often determined by the horizontal grid spacing delta x in this study idealized simulations of deep moist convection over land are performed to assess the convergence behavior of a crm at delta x 8 4 2 1 km and 500 m two types of convergence estimates are investigated bulk convergence addressing domain averaged and integrated variables related to the water and energy budgets and structural convergence addressing the statistics and scales of individual clouds and updrafts results show that bulk convergence generally begins at delta x 4 km while structural convergence is not yet fully achieved at the kilometer scale despite some evidence that the resolution sensitivity of updraft velocities and convective mass fluxes decreases at finer resolution in particular at finer grid spacings the maximum updraft velocity generally increases and the size of the smallest clouds is mostly determined by delta x a number of different experiments are conducted and it is found that the presence of orography and environmental vertical wind shear yields more energetic structures at scales much larger than delta x sometimes reducing the resolution sensitivity overall the results lend support to the use of kilometer scale resolutions in crms despite the inability of these models to fully resolve the associated cloud field