kinematic models of fluvial terraces over active detachment folds constraints on the growth mechanism of the kashi atushi fold system chinese tian shan during detachment folding the relationship between differential uplift and shortening depends on the mechanism of fold growth such as limb rotation or hinge migration and may vary over the lifetime of a fold thus neither long term shortening rates nor the present fold geometry unambiguously constrain the kinematics of fold growth where rivers cut through growing anticlines flights of abandoned fluvial terraces act as passive kinematic markers as shortening progresses the terraces become deformed and thereby preserve critical information about the kinematics and evolution of active fold growth to constrain recent fold growth across three detachment folds in the kashi atushi fold system in the sw tian shan china we surveyed flights of deformed terraces and compared them with geometric models of successively emplaced horizontal unconformities terraces across pregrowth strata deformed by hinge migration limb rotation and a combination of the two migration of angular hinges and curved hinge zones were also compared each kinematic model predicts both a distinct geometry for the deformed terraces and contrasting angular relationships between the terraces and the pregrowth strata notably limb rotation and migration of curved hinge zones result in progressively rotated terraces that cut across pregrowth strata whereas all limb lengthening models result in parallelism between pregrowth strata and terrace straths across much of the fold the kashi atushi terraces show clear evidence of abandoned axial surfaces concentrated deformation near the core of the folds and progressive tilting with age when compared to the model predictions the folds are likely growing by a combination of limb rotation in the tight cores of the folds and hinge zone migration of pregrowth strata across the flanks of the folds

sea level changes in a back arc foreland transition the late carboniferous permian karoo basin of south africa abstract the late carboniferous to early permian succession in the karoo basin consists in ascending stratigraphic order of diamictites mudrocks greywackes and immature sandstones the diamictites are interpreted as glacigene deposits laid down by a marine ice sheet on a shelf post glacial suspension settling of predominantly mud occurred on the basin floor during open marine and later brackish conditions basin floor fan deposits accumulated in the foredeep whereas deltaic mud silt and sand finally infilled the basin glacigene sedimentation occurred in a back arc basin during the late carboniferous and early permian the post glacial succession accumulated in a foreland basin in which the rising orogenic belt was the predominant sediment source relative sea levels following the major namurian regression apparently remained low during the extensive gondwana glaciation marine ice sheets are highly sensitive to sea level fluctuations and minor sea level rises probably climatically controlled were recorded as interglacials when parts of the marine ice sheet collapsed final collapse of the marine ice sheet was associated with a major transgression post glacial mudrock deposition was characterised by relatively high sea levels except for the period of basin floor fan deposition when there was a sea level lowstand final infilling of the basin by prograding deltas was accompanied by a major regression the late carboniferous to early permian sea level fluctuations in the karoo basin show correspondence with global eustatic cycles reflecting low tectonic interference with sea level patterns however late permian sea levels were predominantly tectonically controlled as a result of foreland basin evolution possible global eustatic events complemented apparent sea level changes within the basin during this period

search for milankovitch patterns among oolitic ironstones the stratigraphic record of about 175 oolitic ironstones is sparse yet it portrays several meaningful patterns repeated ironstone episodes occurred in only about 10 major sedimentary basins which were marked by relative tectonic stability or subdued orogeny intervals between episodes varied but were mostly a few to several million years long repetitions on this scale are commonly construed as global rise and fall of sea level the pattern persisted for a few tens of million years in fore deeps several tens of million years on unstable cratons and microcontinents and more than 100 m y in intracratonic basins within the congenial habitats an ironstone developed locally between each of several successive shallow marine upward shoaling detrital sequences these asymmetric units normally a few meters to a few tens of meters thick recurred on average every 250 to 500 kyr commonly fewer than 10 ironstone bearing sequences are involved during a very long lapse in normal sedimentation between such sequences stacked ironstones accumulated on the same short time scale speculation about short time scale patterns is poorly constrained but several other repetitive stratigraphic successions with a several hundred thousand year cadence have been attributed tentatively to the 400 000 year milankovitch climate cycle it is unclear how this would exert a eustatic control without the waxing and waning of continental glaciers

hierarchal genetic stratigraphy a framework for paleoceanography a detailed genetic stratigraphic framework for paleoceanographic studies can be derived by describing correlating interpreting and predicting stratigraphic sequences relative to a hierarchy of their constituent time stratigraphic transgressive regressive units t r units t r unit hierarchies are defined and correlated using lithostratigraphic and paleoecologic data but correlations can be enhanced or checked tested to confirm or deny with objective biostratigraphic magnetostratigraphic or chemostratigraphic data such chronostratigraphies can then be bracketed by radiometric ages so that average periodicities for t r units can be calculated and a hierarchal geochronology derived t r units are inferred to be the net depositional result of eustatic cycles of sea level change and can be differentiated from autocyclic deepening shallowing units because the latter are noncorrelative intrabasinally boundaries between t r units are conformable or unconformable genetic surfaces of two types transgressive surfaces and climate change surfaces the latter are useful for correlating minor transgressive phases through nonmarine intervals thereby deriving information linking paleoclimatic and paleoceanographic processes permo carboniferous sequences can be analyzed relative to a hierarchy of six scales of genetic t r units having periodicities of 225 300 m y first order 20 90 m y second order 7 13 m y third order 0 6 3 6 m y fourth order 300 500 10 years fifth order and 50 130 10 years or less sixth order paleogeographic maps for the time of maximum transgression transgressive apex of successive fifth order t r units 5 25 m thick in the glenshaw formation upper pennsylvanian northern appalachian basin delineate delta lobes embayments islands and linear seaways relative extent of marine inundation on the fifth order maps was used to delineate fourth order t r units and the fourth order t r units constitute the transgressive half of a third order t r unit this third fourth and fifth order hierarchy is correlated more than 1200 km 750 miles to the western interior basin and is confirmed with limited objective biostratigraphy

oolitic sandbody depositional models and geometries mississippian of southwest britain implications for petroleum exploration in carbonate ramp settings abstract a 1000 m thick early mississippian carbonate supersequence the carboniferous limestone of southwest britain consists of three third order depositional sequences these comprise parasequences in various configurations and the whole forms a carbonate ramp stack within this framework five major oolitic carbonate sandbodies developed a castell coch limestone b stowe oolite c brofiscin oolite d gully oolite and e high tor limestone the depositional regime was storm and wave dominated throughout and the major sandbodies represent a range of progradational carbonate beaches barriers and detached subtidal shoals analysis of the three dimensional shapes and distribution of these five examples shows that they evolved to produce three major carbonate sandbody geometries a strings b sheets and c wedges these geometries are characterised using the five field examples and offered as a template which may assist in the exploration and reservoir modelling of petroleum rich high energy ramp systems progradation for up to 40 km of barrier islands stowe oolite and beach ridge plains gully oolite formation generated strings and thick sheets individually up to 10 20 m thick thin shoreface retreat carbonate packstone grainstone sheets up to 5 m thick high tor limestone developed during transgressions as veneers across flooding surfaces these are comparable with sheet sands developed in siliciclastic shelf depositional systems progradation for up to 30 km and vertical aggradation of shoreline detached oolite shoals castell coch limestone brofiscin oolite generated basinwards expanding or thinning wedges up to 30 m thick tectonically controlled stacking of strandplain sheets produced a composite carbonate sandbody up to 80 m thick gully oolite the intrinsic sedimentary and extrinsic eustacy tectonism climate factors which controlled these sandbody geometries are addressed establishing the positions of the sandbodies accurately within depositional sequences allows them to be located within inferred seismic sequence geometries and provides one possible solution to the difficult problem of predicting carbonate facies distribution in subtle stratigraphic plays in this ramp system the most homogeneous sandbodies up to 30 m grainstones with greatest reservoir facies potential are represented by shoal belt wedges potential grainstone reservoir facies in the prograding shorelines are limited to the upper parts of individual shoreface sequences max 10 m grainstones for shoreline carbonate sandbodies the greatest reservoir and stratigraphic trapping potential exists in the earliest ramp parasequences where enveloping offshore sediments are siliciclastic mudstones in later stages potential seals are likely to be less reliable low porosity outer ramp carbonates

new timing and geochemical constraints on the capitanian middle permian extinction and environmental changes in deep water settings evidence from the lower yangtze region of south china the capitanian guadalupian witnessed one of the major crises of the phanerozoic and like many other extinctions it coincided with the eruption of a large igneous province in this case the emeishan traps of sw china however the timing and causal relationships of this event are in dispute this study concentrates on the deep water chert mudstone strata of the gufeng formation and its transition to the yinping formation at chaohu zircons from tuffs in the uppermost gufeng formation yield a u pb age of 261 6 1 6 ma and comparison with sections around emeishan suggests that the tuffs appeared in the jinogondolella altudaensis conodont zone and persisted to the jinogondolella xuanhanensis zone this coincides with the emeishan eruptions and suggests that the tuffs probably derived from this province mineralogical and geochemical characteristics also show the tuffs are of acid volcanogenic origin and have a geochemical fingerprint of the emeishan large igneous province our dating shows that a crisis amongst radiolarian and a subsequent productivity decline occurred during the middle capitanian prior to the guadalupian lopingian boundary the emeishan eruptions began immediately before this indicating a likely causal relationship between these events major regression and marine anoxia euxinia are two other important extinction relevant environmental changes that occurred during this critical interval

symmetrical and upward shallowing cycles in the middle devonian of new york state and their implications for the punctuated aggradational cycle hypothesis the middle devonian eifelian and givetian hamilton group in western and central new york composed largely of fossil rich marine shelf and slope facies is subdivisible into repetitive facies sequences of varying thicknesses minor cycles include 1 to 3 m thick upward coarsening shale to siltstone hemicycles resembling sixth order punctuated aggradational cycles pacs in central new york probably correlative 0 5 1 0 m shale to argillaceous nodular limestone couplets occur in western areas major cycles in western new york include subsymmetrical 3 to 5 m thick packages with medial limestone beds analogous to upper limestones of pennsylvanian cyclothems the center of each cycle marks a regressive maximum and grades vertically above and below into black shale or dark gray mudstone corresponding in a facies sense to cyclothemic core shales in the midcontinent pennsylvanian these widespread units appear to be allocyclic in nature and approximate fifth order transgressive regressive cycles based upon average unit thickness relative to the encompassing well zoned hamilton sequence correlations show that most key regressive events marked by limestones in western new york are expressed by equivalent siltstone or fine sandstone units in central new york most cycles which are nearly symmetrical in western new york grade eastward into 5 to 20 m upward coarsening pac motif hemicycles these asymmetric cycles apparently reflect rapid sediment aggradation to limits imposed by wave energy in a region of abundant sediment supply further minor shallowing was accompanied by winnowing and bypass of fine grained sediments generating condensed capping deposits of coarser silt and sand reworked shells and commonly phosphatic nodules ensuing sea level rises were accompanied by initial sediment starvation followed by sedimentation in deeper water hence asymmetrical upward shallowing hemicycles pacs appear to grade offshore into thin but symmetrical cycles both pac and symmetrical motifs are local responses to the same probably allocyclic sea level fluctuations we suggest that the pac motif is partially facies controlled being largely restricted to shallow shelf settings with relatively high rates of sediment accumulation

the pennsylvanian permian transition in the low latitude carbonate record and the onset of major gondwanan glaciation abstract recent studies suggest a marked expansion of glacial ice across much of gondwana beginning in the earliest permian because expansion of glacial ice results in a lowering of sea level the imprint of ice expansion should be evident worldwide as significant exposure event hiatuses or other evidence for sea level drop at or near the pennsylvanian permian boundary this literature review investigates the signature of an early permian expansion of gondwanan ice through examination of stratigraphic records from eight carbonate dominated palaeotropical regions across pangaea tropical carbonate environments are used because most form in tectonically quiescent regions and are sensitive indicators of eustatic change correlation between stratigraphic sections is achieved using the most current biostratigraphic and absolute time constraints available all studied sections show a sequence boundary or basinward shift in facies at or near the pennsylvanian permian boundary supporting the hypothesis of a significant expansion of glacial ice and global eustatic lowstand beginning in the early permian by contrast a series of mid sakmarian kungurian transgression events in the palaeotropics are interpreted to reflect the asynchronous deglaciation of gondwana the stratigraphic framework developed herein will allow for better correlations among stratigraphic records from gondwana and northern pangaea which will ultimately improve the understanding of how carbonate systems respond to global icehouse conditions such as during the late palaeozoic

graphic correlation in frontier petroleum provinces application to upper paleozoic sections in the tarim basin western china when they were graphically correlated against a composite standard database paleontologic data sets from the carboniferous and lower permian of the western tarim basin revealed a punctuated stratigraphic succession in which most of geologic time is contained within regional hiatuses up to 15 m y duration these hiatuses occur beneath rock packages of late bashkirian middle moscovian late moscovian early kasimovian late gzhelian early asselian and early sakmarian artinskian ages this interpretation differs from other views that hold that permian carboniferous deposition in the tarim basin was continuous or nearly continuous with only minor breaks the results suggest that late paleozoic sedimentation in the tarim basin was controlled primarily by local processes not by third order global sea level cycles 1 3 m y duration the graphic correlation technique is capable of superior biostratigraphic resolution because it uses the ranges of all fossils within a data set not just guide fossils or those associated with zonal definitions moreover a composite standard that is linearly calibrated to geologic time makes possible inferences regarding rates of rock accumulation within stratigraphic sequences and the durations of sequence bounding hiatuses the resulting chronostratigraphic framework enables and constrains sequence stratigraphic and seismic stratigraphic interpretations

recognition of diagenetic contribution to the formation of limestone marl alternations a case study from permian of south china abstract limestone marl alternations lmas have been extensively used in studies of sedimentology cyclostratigraphy and paleoclimatology however it has long been debated whether lmas are derived from primary sedimentation or from diagenetic alteration and the markers to distinguish one source from the other remain ambiguous in this study we investigate widespread permian lmas from various depositional settings in south china using traditional petrographic mineralogical and major element al2o3 vs tio2 methods as well as emerging trace and rare earth element ree analyses performed using solution based and in situ techniques the original depositional differences of the limestone and its coupled marl beds can be identified based on 1 the high volumes of siliciclastic minerals in the marls 2 unremarkable differential compaction 3 the recognizable signatures of the detrital admixture i e the al zr and th characteristics and 4 flattened shale normalized ree patterns diagenetic lmas are characterized by the compaction of fossils rare aragonite skeletons and abundant diagenetic clays sepiolite and talc preserved in the marl beds we also identified fully diagenetic lmas originating from primary carbonate sedimentation based on two almost completely consistent seawater like ree patterns with diagnostic positive la and negative ce anomalies la la sn 1 64 0 17 ce ce sn 0 73 0 05 superchondritic y ho 47 4 and depleted light rees relative to high rees pr yb sn 0 39 0 09 diagenesis also dominates the formation of lmas with limited terrigenous input in shallow water carbonate depositional environments it is likely that both the active metabolic processes in early diagenesis especially aerobic sulfide oxidation and the temporal palaeoceanographic conditions e g high levels of dissolved oxygen and sulfate play crucial roles in the genesis of the diagenetic lmas in the permian strata of south china

postglacial transgressions in late paleozoic basins of western argentina a record of glacioeustatic sea level rise the areas marginal to main glaciated centers are appropriate sites to distinguish the record of glacioeustatic sea level fluctuations the late paleozoic basins of western argentina show a marginal position with respect to the glaciated areas of eastern south america brazil in three of these basins tarija calingasta uspallata and central patagonian widespread glacial marine diamictites and their gravity reworked counterparts pass upward to open marine fine clastics mudstones shales and scarce fine sandstones with fossils of the levipustula zone of middle carboniferous late namurian westphalian age the presence of fine grained marine sequences capping the diamictitic deposits is interpreted as the sedimentary response to a glacioeustatic sea level rise expressed as a transgression in stratigraphic terms the glacioeustatic nature of this sea level rise is confirmed by the interbasinal facies based correlation of the transgressive episode and the paleolatitudinal positioning of this portion of gondwanaland during carboniferous times

lacustrine delta deposits and their effects on coal mining in a surface mine in derbyshire england abstract five late carboniferous pennsylvanian coal seams and associated inter seam strata have been examined at lodge house surface mine in the east midlands coalfield of england deposition of these coal seams and their accompanying inter seam intervals occurred in an equatorial fluvio lacustrine environment in an area approximately halfway between the depocentre and the southern margins of the pennine basin controls on the onset of inter seam sedimentation and cessation of peat formation appear to have operated at two scales fourth order glacio eustatic rises exerted the dominant control over formation of peats in laterally extensive mires however fifth order and smaller scale autocyclic mechanisms specifically avulsion are believed to have accompanied splitting of other seams close to but beyond the confines of the mine a study of contrasting lacustrine delta deposits occupying two of the inter seam intervals has enabled proximal distal wave dominated and delta distributary channel sub facies to be recognised the lacustrine deltas prograded rapidly into shallow but extensive freshwater lakes and both delta lobe switching and avulsion of delta distributary channels were important mechanisms the lower lacustrine delta sequence is characterised by mud filled delta distributary channels near the top of the interval the upper sequence is dominated by wave formed structures and massive sandstone delta distributary channels which formed during a period of episodic floods and strong winds lacustrine delta deposits generally create good mining conditions but delta distributary channels can present difficulties in underground mines mud filled delta distributary channels subject to early compaction can give rise to swilleys elongate depressions resulting in thickness changes and undulation of the overlying seam when filled with strong well cemented abrasive sandstone delta distributary channel deposits can be hard to excavate at lodge house the narrow width of the delta distributary channels meant that they were not detected by drilling prior to mining thus outcrop studies should be used to complement subsurface data as they can significantly enhance our understanding of small scale features

devonian carboniferous boundary glacioeustatic fluctuations in a platform to basin direction a geochemical approach of sequence stratigraphy in pelagic settings abstract we investigated high resolution stratigraphic distribution of selected major and trace elements and gamma ray spectra of fourteen devonian carboniferous d c boundary sections of europe located in the late palaeozoic laurussia and gondwana the aim was to trace the geochemical signature of a marked forced and normal regressive interval which was associated with rapid progradation of siliciclastics into the marine carbonate systems rhenish massif and a prominent hiatus in shallow water ramp settings namur dinant basin this interval represents the late devonian hangenberg event hbe sensu lato middle praesulcata conodont zone as defined by previous authors this regressive interval fsst to lst correlates with thin shale layers hbe shale sandwiched between monotonous nodular calcilutite calcisiltite successions at five pelagic sections of moravia carnic alps montagne noire and pyrenees in all sections with continuous d c sedimentation i e except those of the namur dinant basin the hbe s l interval is accompanied by elevated percentages of detrital proxies al k rb zr and changes in their ratios zr rb k al rb k which are normally interpreted as indicators of increased siliciclastic input provenance and grain size zr rb and other proxies are traceable even without apparent lithological evidence and can therefore facilitate stratigraphic correlation paleoredox and productivity proxies u th and ni rb enrichment factors only rarely show elevated values in the hangenberg black shale interval indicating that the associated water dysoxia anoxia was a local rather than global phenomenon global correlations based on the hbe black shales should therefore be dropped in favor of the hbe s l interval moreover analysis of sedimentation rates in the upper expansa to kockeli zone interval using the published radiometric ages suggests that the hbe s l was a time of significant increase in the rate of siliciclastic supply into the ocean even in the most distal pelagic sections consequently the previous interpretation of the hbe black shale as a condensed succession deposited during rapid sea level rise seems unlikely we interpret the hbe s l i e including the hbe black shale as a marine record of glacioeustatic sea level drop and increased aeolian transport in connection with late devonian climatic cooling and glaciation the set of geochemical markers related to the late devonian sea level fluctuation can be used for super regional to global correlations from platform to basin settings moreover they can facilitate current efforts to determine a new d c boundary definition

physical and chemical stratigraphy suggest small or absent glacioeustatic variation during formation of the paradox basin cyclothems the paradox basin cyclothems previously have been interpreted as milankovitch style glacial interglacial cycles from the late paleozoic ice age but an unambiguous test for a glacioeustatic origin has not been conducted a high resolution coupled chemical and physical stratigraphic analysis of two outcrop sections and three core segments provides new evidence that supports either minor sea level change of several meters or an autocyclic mechanism for parasequence formation high amplitude sea level change is ruled out by the scale of thin top negative isotopic meteoric diagenesis trends associated with parasequence tops and subaerial exposure fabrics isotopic gradients from shelf light to basin heavy indicate that parasequences are deposited diachronously with isotopes of more distal sections recording increased basin restriction these results support the idea that the late pennsylvanian was a prolonged period of relatively static eustasy agreeing with recent studies in the western usa the methods provide a new set of tools and context for extracting environmental information from cyclic upward shallowing carbonate parasequences

late paleozoic depositional sequences are synchronous and worldwide more than fifty transgressive regressive depositional sequences are present in carboniferous and permian shallow marine successions on stable cratonic shelves worldwide these were synchronous depositional events resulting from eustatic sea level changes that generally ranged from 100 to 200 m each transgressive regressive sequence is correlatable using current fossil knowledge they average about 2 m y and range from 1 2 to 4 m y in length the presence within these strata of numerous synchronous unconformities of considerable duration and worldwide extent suggests that the fossil record is very incomplete and that we are studying a punctuated fossil record and not a punctuated evolution based on a highly irregular mutation rate these late paleozoic transgressive regressive depositional sequences facilitate correlations because depositional histories of a rock succession can support interpretations of faunal assemblages and faunal similarities in evaluating age relationships

effects of sedimentation tectonics and glacio eustasy on depositional sequences pennsylvanian minturn formation north central colorado the pennsylvanian minturn formation was deposited adjacent to the ancestral front range on the eastern margin of the actively subsiding central colorado basin during a time of high frequency eustatic sea level changes attributed to glaciations in the southern hemisphere in the 100 km2 study area near mccoy colorado up to nine depositional cycles composed of marine and nonmarine deposits are recognized three tectonic blocks were subsiding at different rates in the study area detailed correlation of measured sections along well exposed outcrop belts has shown that seven of these cycles extend continuously across the field area which includes two delta complexes two cycles are absent on the central block the study area is well suited for examining the role of local tectonic vs eustatic processes in controlling the distribution of sedimentary deposits in the study area cycles are bounded by erosional surfaces with as much as 43 m of relief these surfaces are inferred to be sequence boundaries and are overlain by braided fluvial conglomerates inferred to be incised valley fill deposits marine flooding surfaces overlie the conglomerates the copyright 1997 the american association of petroleum geologists all rights reserved 1manuscript received january 17 1996 revised manuscript received october 18 1996 final acceptance march 20 1997 2department of geological sciences university of colorado at boulder campus box 250 boulder colorado 80309 0250 present address department of geology university of colorado at denver campus box 172 p o box 173364 denver colorado 80217 3364 i thank the members of my doctoral dissertation committee at the university of colorado ted walker martin lockley alan scott david budd and john pitlick for their advice and guidance during the course of my research financial support was provided by the rocky mountain section of sepm the colorado mountain club union pacific resources and the department of geological sciences at colorado university boulder charles ross provided fusulinid identifications and biostratigraphic zonation i thank paul weimer colorado university boulder for advice and encouragement and keith miller kansas state university for carefully reviewing a preliminary draft of this paper aapg reviewers william devlin romeo flores denise stone and elected editor kevin biddle provided many suggestions that greatly improved the final manuscript i also thank the residents of mccoy bond and copper spur colorado for granting access to their property and for all their kindness while i was working in the field

no global scale transgressive regressive cycles in the thanetian paleocene evidence from interregional correlation abstract a detailed examination of transgressions and regressions that occurred during the thanetian 58 7 55 8 ma may provide an important constraint on the global palaeoenvironment seven tectonically stable regions the eastern russian platform northwestern europe northwestern africa northeastern africa the arabian platform the northern gulf of mexico and southern australia represent exceptional records of transgressive regressive t r cyclicity their chronostratigraphic frameworks are sufficiently well constrained to permit accurate correlation surprisingly except for a generally regressive trend occurring in the late thanetian no common t r cycles can be delineated which indicates an absence of global scale t r cyclicity during the thanetian furthermore we find no clear correspondence between documented t r patterns and previously reported eustatic changes we suggest that a warm climate and an absence of major glaciations in the early middle thanetian coupled with only slow eustatic change expected from tectonic processes stabilized thanetian eustatic sea level regional subsidence or uplift possibly generated by mantle flow in the form of dynamic topography governed transgressions and regressions locally and resulted in an inconsistency between t r cycles in different parts of the globe the late thanetian regressive episode which preceded the paleocene eocene thermal maximum may be linked to an advance of glaciation

glacio eustasy depositional environments diagenesis and reservoir character of goen limestone cyclothem desmoinesian concho platform central texas the goen limestone desmoinesian of concho and runnels counties central texas consists of three stacked transgressive regressive sequences each cycle consists of a thin basal transgressive unit clayey facies deposited in a deeper water lower ramp setting and thick regressive limestones algal foraminiferal and bryozoan facies representing middle to upper ramp mound mound associated and back mound environments glacio eustatic sea level fluctuations were the dominant control on the observed cyclicity and facies distribution the major porosity forming process in the goen limestone was early leaching by freshwater lenses that migrated in response to glacio eustatic sea level changes the dominant porosity reducing processes included early cementation in a meteoric phreatic environment and late stage saddle dolomitization in a deeper burial connate environment the hydrocarbon producing regressive middle and upper ramp units foraminiferal and bryozoan facies underwent the most complex diagenetic histories and contain extensive secondary pores the presence or absence of penetrating freshwater lenses and the distribution of green phylloid algae and secondary pore filling cements were the major factors controlling goen reservoirs numerous cyclic carbonate reservoirs with depositional and diagenetic histories similar to the goen are present in the desmoinesian section of central texas e g caddo odom gardner capps and dog bend limestones late paleozoic mound associated and back mound carbonate reservoirs may be of greater importance in petroleum exploration than algal mounds one of the most frequently exploited late paleozoic carbonates of north america

a post new horizons global climate model of pluto including the n 2 ch 4 and co cycles abstract we have built a new 3d global climate model gcm to simulate pluto as observed by new horizons in 2015 all key processes are parametrized on the basis of theoretical equations including atmospheric dynamics and transport turbulence radiative transfer molecular conduction as well as phases changes for n 2 ch 2 and co pluto s climate and ice cycles are found to be very sensitive to model parameters and initial states nevertheless a reference simulation is designed by running a fast reduced version of the gcm with simplified atmospheric transport for 40 000 earth years to initialize the surface ice distribution and sub surface temperatures from which a 28 earth year full gcm simulation is performed assuming a topographic depression in a sputnik planum sp like crater on the anti charon hemisphere a realistic pluto is obtained with most n 2 and co ices accumulated in the crater methane frost covering both hemispheres except for the equatorial regions and a surface pressure near 1 1 pa in 2015 with an increase between 1988 and 2015 as reported from stellar occultations temperature profiles are in qualitative agreement with the observations in particular a cold atmospheric layer is obtained in the lowest kilometers above sputnik planum as observed by new horizons s rex experiment it is shown to result from the combined effect of the topographic depression and n 2 daytime sublimation in the reference simulation with surface n 2 ice exclusively present in sputnik planum the global circulation is only forced by radiative heating gradients and remains relatively weak surface winds are locally induced by topography slopes and by n 2 condensation and sublimation around sputnik planum however the circulation can be more intense depending on the exact distribution of surface n 2 frost this is illustrated in an alternative simulation with n 2 condensing in the south polar regions and n 2 frost covering latitudes between 35 n and 48 n a global condensation flow is then created inducing strong surface winds everywhere a prograde jet in the southern high latitudes and an equatorial superrotation likely forced by barotropic instabilities in the southern jet using realistic parameters the gcm predict atmospheric concentrations of co and ch 4 in good agreement with the observations n 2 and co do not condense in the atmosphere but ch 4 ice clouds can form during daytime at low altitude near the regions covered by n 2 ice assuming that nucleation is efficient enough this global climate model can be used to study many aspects of the pluto environment for instance organic hazes are included in the gcm and analysed in a companion paper bertrand and forget icarus this issue

penitentes as the origin of the bladed terrain of tartarus dorsa on pluto simulations of pluto suggest that the sharp ridges in the tartarus dorsa region of pluto are penitentes that formed over the past tens of millions of years observations by the new horizons spacecraft have revealed a host of features on the surface of pluto among the most intriguing of these is an area of bladed terrain in the tartarus dorsa region of the dwarf planet several potential origins have been suggested on the basis of comparisons with similar structures found on earth such as the hard elongated snow formations known as nieves penitentes or simply penitentes which are found at high altitudes in the andes and other mountain regions john moores et al report simulations that reproduce the observed tri modal orientation and spacing of the tartarus dorsa features by deepening penitentes these penitentes deepen by about one centimetre per orbital cycle in the present era growing only during periods of high atmospheric pressure suggesting a formation timescale of several tens of millions of years penitentes are snow and ice features formed by erosion that on earth are characterized by bowl shaped depressions several tens of centimetres across whose edges grade into spires up to several metres tall1 2 3 penitentes have been suggested as an explanation for anomalous radar data on europa4 but until now no penitentes have been identified conclusively on planetary bodies other than earth regular ridges with spacings of 3 000 to 5 000 metres and depths of about 500 metres with morphologies that resemble penitentes have been observed by the new horizons spacecraft5 6 7 8 in the tartarus dorsa region of pluto 220 250 e 0 20 n here we report simulations based upon a recent model3 representing conditions on pluto7 9 in which deepening penitentes reproduce both the tri modal north south east west and northeast southwest orientation and the spacing of the ridges of this bladed terrain at present these penitentes deepen by approximately one centimetre per orbital cycle and grow only during periods of relatively high atmospheric pressure suggesting a formation timescale of several tens of millions of years consistent with crater ages this timescale implies that the penitentes formed from initial topographic variations of no more than a few tens of metres consistent with pluto s youngest terrains

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

episodic nature of the cenozoic marine record various suggestions of a geological periodicity of 2 7 m y have been made in the literature if such periods exist they fall between the earth orbital milankovitch periods and the solar system s galactic oort periods and have no known internal or external source to study the period range 1 10 m y four types of cenozoic marine data were subjected to formal time series analysis no significant periodicities were found and only a mean interval between global marine episodes 5 2 m y could be defined possible causes of the variability are discussed

depositional environments and sequence stratigraphy of the late carboniferous early permian coal bearing successions shandong province china sequence development in an epicontinental basin abstract this study focuses on the late carboniferous early permian coal bearing successions in shandong province north china in order to understand the depositional processes and sequence stratigraphic framework in an epicontinental basin based on detailed analysis of eleven facies five facies assemblages fas were recognized in the studied succession fa1 3 are present mainly in the benxi and taiyuan formations and consist of mixed siliciclastic and carbonate lithofacies representing eluvial lagoon barrier lagoon and tidal flat environments fa4 occurs in the shanxi formation and consists mainly of interbedded medium to fine sandstone siltstone mudstone and coal lithofacies representing river dominated deltaic environments fa5 is characterized by interbeds of trough cross stratified coarse sandstone and silty mudstone mainly in the lower shihezi formation which was deposited in meandering river channel and floodplain three third order sequences were established based on the vertical arrangement of facies assemblages and identification of physical surfaces i e subaerial unconformity transgressive surface and regressive surface each sequence comprises a transgressive systems tract tst and a highstand systems tract hst tst of sequence 1 is composed of eluvial lagoonal deposits fa1 whereas hst formed in lagoon barrier and tidal flat settings fa2 and fa3 tst of sequence 2 formed in a barrier lagoon system fa2 whereas hst is characterized by repetitive accumulation of interbedded limestone sandstone mudstone and coal deposited under lagoonal and tidal flat settings fa2 and fa3 tst of sequence 3 comprises fa2 and hst mainly fa4 deposited in a river dominated shallow water delta system sequence 3 is overlain by a fluvial sequence fa5 the three third order sequences in the shandong region are generally correlated with those in the taebaeksan basin south korea the eastern part of the north china block the relative sea level curves established in the two regions show a generally similar long term rising trend

the devonian and carboniferous of the moscow syneclise russian platform stratigraphy and sea level changes abstract the moscow syneclise is a vast sedimentary basin located in the centre of the east european platform the palaeozoic sequence of this syneclise and especially its devonian carboniferous part is most suitable for sea level fluctuation analysis the devonian and carboniferous sediments consist mainly of shallow marine carbonates containing several minor terrigenous intervals they attain total thicknesses of up to 1 5 km the modern stratigraphic scale includes 33 regional stages for the devonian and 32 for the carboniferous correlation of this scale with global scales is supported by conodont miospore and foraminifera zonations the new calibrated devonian and carboniferous relative sea level curves for the moscow syneclise reflect late eifelian mid frasnian early tournaisian late visean early serpukhovian and moscovian gzhelian transgressions several of these sea level changes which are particularly evident on the margins of the moscow syneclise originated in response to differential tectonic movements of the voronezh anteclise and the tokmovo uplift as well as to vertical oscillations of the entire east european craton

facies and petrophysical signature of the tournaisian visean lower carboniferous sea level cycle in carbonate ramp to basinal settings of the wales brabant massif british isles we studied the relationships between stratigraphic distribution of outcrop spectral gamma ray magnetic susceptibility and carbonate facies stacking patterns across the regionally significant transgressive regressive cycle at the tournaisian visean boundary tn v early carboniferous in southern great britain and ireland south wales north staffordshire and dublin basin the tn v boundary coincides with a prominent climatic pulse connected with the late paleozoic glaciation of gondwana the aim was to correlate the gamma ray and magnetic susceptibility log patterns in carbonate ramp and basin settings and discuss the global regional nature and magnitude of this transgressive regressive cycle a robust ramp to basin correlation was produced based on the log patterns facies stacking patterns and foraminifer biostratigraphy the concentrations of k and th the clay gamma ray values and partly magnetic susceptibility are dependent on facies and show systematic changes along the inferred bathymetric profile from inner ramp to outer ramp and basin a model of carbonate productivity driven dilution of fine grained siliciclastics in caco3 as the major control on the petrophysical patterns is discussed the cleaning up and cleaning down petrophysical trends are related to down dip and up dip shifts of the carbonate factory with changing relative sea level in middle to outer ramp and basin settings this generates petrophysical trends just opposite to paleozoic carbonate shelves where peaks in magnetic susceptibility are known to be associated with peak regressions a distinct late tournaisian to early visean regressive to transgressive cycle with a prominent sequence boundary located close to the tn v stage boundary can be seen in the sections glacioeustatic origin of the sequence boundary is inferred from its correlation with tn v boundary sections from europe carbon isotope data from south china and the glacial deposits in the southern hemisphere mentioned by previous authors

the mid capitanian middle permian mass extinction and carbon isotope record of south china abstract conodont c isotope and fossil and facies data are presented for the capitanian middle permian mass extinction record seen in platform carbonates maokou and wuchiaping formations of south china where limestones interdigitate with the volcanic succession of the emeishan large igneous province the maokou formation provides an extinction record marked by the loss of keriothecal walled fusulinaceans and a turnover in calcareous algae in sections within the emeishan province this crisis occurs at the base of the oldest record of volcanism from the jinogondolella altudaensis conodont zone of mid capitanian age around the periphery of the emeishan province this extinction level lies within the upper part of the maokou formation at a level where platform carbonate deposition was frequently interrupted by thick volcanic ash depositional events the assemblages of the uppermost maokou formation are characterised by typical late permian taxa although these levels still lie within the middle permian guadalupian series disaster taxa such as earlandia and diplosphaerina are locally prolifically abundant in the aftermath of the mass extinction the crisis is particularly noteworthy amongst photosynthetic taxa such as calcareous algae and fusulinaceans that probably harboured photosymbionts therefore a kill mechanism involving cooling from explosive volcanism and potentially acid rain from sulphate aerosols appears appropriate a composite 13ccarb curve calibrated against a high resolution conodont biostratigraphy reveals a major intra capitanian negative excursion of 5 superimposed on typically heavy 4 5 middle permian values this curve can also be recognised in panthalassan seamount carbonates of japan although this requires reassignment of apparently upper permian limestones to the middle permian in both china and japan the capitanian mass extinction occurs during the early stage of this major intra capitanian negative excursion assuming typical platform carbonate accumulation rates the records of the maokou formation suggest 13ccarb values fell at 0 01 kyr suggesting a catastrophic origin such as gas hydrate destabilisation is unlikely although a volcanic source is possible

coupled sedimentary and δ13c records of late mississippian platform to slope successions from south china insight into δ13c chemostratigraphy abstract variability in stratigraphic accumulation rates and distribution of stratal hiatuses along with strong endemism of index fossils hinder regional to global stratigraphic correlation of the visean serpukhovian v s boundary interval late mississippian and thus geological inferences regarding the onset of the late paleozoic ice age here we integrate high resolution 13c time series with detailed sedimentary facies analysis of late visean early serpukhovian v s carbonate platform to slope successions from south china to evaluate the influences of local depositional and diagenetic processes on 13ccarb and to address the correlation issue analysis of 11 sedimentary facies from 5 outcrop sections indicates a restricted platform setting yashui section dominated by bioclastic wacke packstone to lime mudstone in which paleokarst developed and contemporaneous carbonate slope settings dominated by thin bedded lime mudstones intercalated with slumps and calciturbidites based on vertical facies assemblages three depositional units are recognized recording a significant sea level drawdown across the v s boundary multiple negative 13c excursions 1 can be correlated across the v s boundary interval in several slope sections naqing luokun and narao sections variability in the v s boundary 13c record in some sections is interpreted to record truncation physically by submarine erosion by slumps or chemically during karstification a long term decrease in 13c values through the serpukhovian of the yashui section likely records local influences on carbon cycling in the restricted platform setting this negative 13c trend and associated depositional facies at the yashui section can be correlated to the arrow canyon section usa which together with other coeval global sedimentary and geochemical records indicate a widespread eustatic drawdown in the late visean with initial buildup of gondwanan ice sheets we conclude that integrated sedimentary facies analysis and 13c chemostratigraphy can be used for stratigraphic correlation when interpreted within a well constrained sedimentary and carbon isotope regional framework

thermal tides on pluto abstract stellar occultations have shown that vertical profiles of density fluctuations in the atmosphere of pluto typically show wave like structure with an amplitude of a few percent and vertical wavelengths of a few kilometers here we calculate the tidal response of pluto s atmosphere to solar induced sublimation breathing from n 2 frost patches solutions show global scale wave like density structure capable of explaining the observations the atmospheric response is a combination of eastward and westward migrating tides together with a zonally symmetric mode calculated vertical wavelengths and amplitudes are similar to observations

rugose coral biostromes in the late visean mississippian of nw ireland bioevents on an extensive carbonate platform abstract the extensive upper visean asbian platform carbonates in nw ireland bricklieve limestone fm glencar limestone fm and dartry limestone fm contain distinctive rugose coral biostromes which are dominated by different species of the genus siphonodendron these are in stratigraphic sequence pauciradiale biostrome oldest martini biostrome and several junceum biostromes youngest they represent bioevents caused by special short lasting ecological conditions and can be used as approximately synchronous horizons to correlate within the region the pauciradiale biostrome is the thickest laterally most persistent and most variable in facies and biotic composition of all biostromes it formed on a tectonically influenced platform with a landward seaward zonation from northwest to southeast mainly above storm wave base and below fair weather wave base the northwestern streedagh facies is characterized by the presence of clusters of large sheet like colonies of s pauciradiale the intermediate o donnell s rock facies is unique for the predominance of the fasciculate genus solenodendron the southeastern bricklieve facies represents the amalgamation of autochthonous and allochthonous coral debris and bioclastic debris with localized small patches of coral boundstone mass occurrences of fasciculate rugose corals re appear in the martini biostrome this biostrome developed in a shallower water setting just above fair weather wave base on a levelled carbonate platform the junceum biostromes are thinner decimetre to some metres thick and less persistent they formed in deeper water mostly below storm wave base except for the composite 2nd junceum biostrome of the bricklieve mountains which records a period of shallowing according to facies and coral morphologies which were compared with modern scleractinian growth forms sea level variation exerted one of the strong controls on the rise and decline of the biostromes the pauciradiale biostrome formed during an extended shallowing upward cycle in a depth interval leading to the climax of siphonodendron pauciradiale the cycle ended with the development of the martini biostrome in shallow water its demise is probably caused by drowning during the late asbian sea level rise during that time slice the junceum biostromes flourished in deeper water on the platform coral growth ceased almost completely after formation of the junceum biostromes during the falling sea level of the latest asbian siliciclastic input and resulting turbidity as well as turbulence formed a complex cascade of ecological constraints in addition to the local tectonic influences they combined to result in the depth factor which controlled the distribution of predominating coral populations and the succession of the different biostromes in the asbian of nw ireland

tuffs tectonism and glacially related sea level changes carboniferous permian southern namibia abstract the carboniferous permian glacigene dwyka group in southern africa has been widely regarded as amagmatic only in the higher parts of the permian and subsequent younger strata has evidence of magmatism been recognised particularly in the form of pyroclastic fallout ash beds the source of these tuffs has been suggested to be patagonia and west antarctica forming part of an extensive volcanic arc which lay some 1500 to 2000 km to the south and west in their pre break up gondwana positions rhyolitic dacitic and basaltic andesitic tuff beds within the glaciomarine sediments of the dwyka group in namibia reveal new evidence for an early onset of proximal bimodal volcanic activity in southern africa contemporaneous tectonism is recorded by type 1 unconformities and systematic thickness changes across nw se trending extensional normal faults we suggest that this tectonomagmatic period marks initial extensional events in southern namibia and the carboniferous permian volcanic trend appears to coincide with the position of the eventual namibian continental margin significantly the stratigraphic positions of the tuff beds show a distinct association with enclosing marine transgressive depositional sequences most of them coincide with sharply defined flooding surfaces within relatively thick shaly successions reflecting their multiple transgressive nature widening the study context to the latest early permian in southern africa the main karoo basin of southern africa exhibits a similar coincidence of marine transgressions and extrusion of volcanics the relationship between tuff beds and transgressive depositional sequences is not only the result of enhanced preservational potential during transgression but of a genetic coupling between magmatism extensional tectonics and basin subsidence the latter accelerating a rise in relative sea level this interaction is significant not only for understanding potential controls on relative sea level change but also for understanding the early geodynamic evolution of the southern south atlantic continental margin

genetic stratigraphy and depositional systems of the upper devonian lower mississippian price rockwell deltaic complex in the central appalachians u s a abstract rocks of the price and rockwell formations comprise the uppermost devonian lower mississippian deltaic complex in the central appalachians the price formation is dominantly marine and refers to all uppermost devonian lower mississippian rocks above either hampshire group red beds or the marine greenland gap formation and below either the greenbrier limestone group or maccrady formation red beds in the central appalachians the rockwell formation is dominantly non marine and refers to equivalent rocks in south central pennsylvania and the maryland west virginia panhandle region members of the price formation are generally equivalent to discrete genetic events price deposition was initiated in latest devonian time when a regional transgression covered delta and alluvial plain facies of the catskill deltaic complex with protected bay and strandline facies of the oswayo member in west virginia pennsylvania and western maryland farther south these transgressive facies overlie the cloyd conglomerate member a thin regressive transgressive sedimentary wedge and occur in the lower part of the sunbury shale member subsurface berea sandstone deposition corresponded to regional exposure and erosion in the outcrop belt this unconformable surface was overstepped in earliest mississippian time by a major transgression that deposited a variably thick but persistent basal transgressive sandstone during shoreface retreat sandstones that have been referred to the cussewago sandstone in northern west virginia and southwest pennsylvania are part of this basal sandstone eastward these sandstones thicken coarsen and interbed with a polymictic diamictite at the base of the rockwell formation shaly facies of the earliest mississippian transgression overlie the basal sandstone the riddlesburg shale preserves offshore and open bay facies in west virginia that grade eastward to estuarine and restricted back bar lagoon and marsh facies of a barred bay complex in south central pennsylvania and the maryland west virginia panhandle from central west virginia riddlesburg facies grade southward into basinal facies of the sunbury shale member syndepositionally active basement features the west virginia dome and tri state block were structurally positive areas in the foreland basin the tri state block caused truncation of lower mississippian marine facies in western maryland and large scale westward erosional overlap of channel fill sandstones in the upper rockwell formation the west virginia dome was also structurally positive and the basal transgressive sandstone contains phosphatic omission surfaces on the dome crest lack of subsidence caused scour and incision of riddlesburg facies by overlying deltaic facies progradation ensued with fluvial dominant shallow water deltaic systems price rockwell member in northern west virginia and marine dominant deep water deltaic facies farther south a 150 m minimum paleodepth estimate in the foreland basin is based on stratigraphic thickness in southern west virginia following a transgression near the kinderhookian osagean boundary price marine deltaic facies form a coarsening upward sequence to delta plain coals and coastal alluvial plain red beds a 35 m estimate for average storm wave base utilized tempestite proximal distal trends

late devonian and early mississippian bakken and exshaw black shale source rocks western canada sedimentary basin a sequence stratigraphic interpretation the late devonian and early mississippian bakken and exshaw formations are a continuum of regionally correlated organic rich up to 35 total organic carbon black shale source rocks covering much of the western canada sedimentary basin the bakken formation is composed of 1 a black mudstone lower member 2 a gray mudstone sandstone middle member and 3 a black mudstone upper member the exshaw formation beneath the alberta plains and in exposures in the foothills and front ranges of the rocky mountains is composed of 1 a lower black shale member and 2 an upper siltstone member the basal black shale unit of the lower mississippian banff formation overlying the exshaw formation is a second organic rich interval these black shales are regionally significant hydrocarbon source rocks and local reservoirs the middle bakken member is a locally important reservoir rock with substantial economic potential the bakken and exshaw formations and the basal banff black shale are divisible into three systems tracts 1 a transgressive systems tract 2 a lowstand systems tract and 3 a second transgressive systems tract lodgepole and banff formation carbonates overlying the bakken and exshaw formations are part of a highstand systems tract a sequence boundary occurs between the lower and middle bakken members the conformable equivalent of this sequence boundary is within the exshaw black shale member variations in the internal composition of these systems tracts imply that two depocenters 1 the williston basin and 2 the prophet trough and the western margin of the north american craton were affected differently by relative sea level rise and fall during bakken and exshaw deposition because of differences in water depth and sediment accommodation spatial and temporal changes in black shale and gray mudstone sandstone as highlighted by this sequence stratigraphic interpretation may have significant impacts on source rock potential and hydrocarbon reservoir size location and quality

paleosols of late pennsylvanian cyclic strata new mexico cyclically deposited siliciclastic and carbonate rocks of the late pennsylvanian virgilian holder formation of south central new mexico were deposited on a narrow shelf between the pedernal uplift and the orogrande basin in the dry canyon area sacramento mountains shelf to basin palaeotopography is indicated by onlapping beds and primary dips calcareous alteration zones are developed on the tops of major carbonate units these detailed studies confirm earlier interpretations that alteration zones represent subaerial exposure events and provide new evidence for and further documentation of a paleosol environment the paleosols contain 1 rhizoliths 2 tangential needle fibres of calcite 3 five types of alveolar texture 4 upward oriented ribbon spar 5 brownish and clear isopachous spar 6 blackened grains 7 random needle fibres of calcite 8 coated grains 9 micritized grains 10 glaebules 11 desiccation cracks 12 possible microcodium and 13 well developed laminated crusts isopachous cements upward oriented cements which mark the former tops of capillary fringes dark colour and shallow depth of penetration of rhizoliths less than 1 m indicate significant paleosol formation in waterlogged hydromorphic and drier conditions pennsylvanian palaeohydrogeology of the system is reflected in the type of paleosol alteration paleosols developed on subtidal strata and paleosols which drape tens of metres of palaeotopography indicate cyclic sedimentation was not controlled by delta lobe switching local tectonic up and down movement would be an unlikely mechanism to explain the repeated tens of metres of relative sea level fluctuation eustatic sea level fluctuations induced by late pennsylvanian gondwana glaciation probably were of the correct magnitude and frequency to have caused the holder cycles

coal more than a resource critical data for understanding a variety of earth science concepts abstract coal is one of the world s primary energy sources and it is critical for making coke used in steel making and is used for a multitude of chemical products aside from its significance as a fuel or product however coal and data derived from the exploration or mining of coal have also provided the foundation and testing ground for diverse geologic concepts because of coal s economic importance and common variability in thickness distribution and quality it has been critical to collect and correlate a wide variety of surface and subsurface data sets at relatively high spatial frequency which varies from the mine to basinal scale also because many coal beds occur in most coal basins the collection of coal data from multiple beds creates relatively high temporal frequency data sets at scales from laminae to bed to larger unit scale these data have been important for the development and expansion of many earth science concepts including aspects of basin analyses paleogeography paleoclimatology paleontology stratigraphy sedimentology structural geology and tectonics

shallow marine sedimentary facies in the earliest triassic griesbachian cordilleran miogeocline u s a abstract permian history in the cordilleran miogeocline u s a ended with an erosional interval of 1 to 22 million years previous studies of this event focused on unrepresented time faunal extinction regional truncation or physical evidence in local areas another way to view this unconformity is to examine the nature of shallow marine sediments deposited on the erosional surface during the earliest triassic griesbachian transgression as part of this study the rate of the initial mesozoic flood was estimated by determining the extent of the oldest triassic conodont biozone within the study area the calculated rate of transgression over 194 000 km2 occupied by this biozone within the 270 000 km2 depositional area of the earliest triassic dinwoody formation is orders of magnitude greater than those suggested for eustatic sea level change related to glaciation or plate tectonic processes the rapidity of transgression paucity of reworked material at the base of the triassic a general lack of local relief and nearly conformable relations of permian and triassic rocks throughout the region suggest that the triassic sea advanced across a featureless plain the earliest triassic sediments described in this study are restricted to the basal 2 m of the dinwoody formation the generalized geographic distribution of facies within the depositional basin follows evaporites are restricted to the northeast lingula bearing dolomite characterizes the north central sandstone is locally present in the northwest and central areas the southern part is dominated by shaly bedded siltstone with some thin limestone interbeds and calcareous silty shale is present in the west toward the basin center the similarity of basalmost triassic depositional environments to those of the earlier permian documents tectonic rejuvenation of a previous paleogeographic regime that strongly controlled early triassic sedimentation

sequence stratigraphy in proterozoic successions sedimentological logging and facies mapping have been used to identify depositional sequences bounded by subtle but regionally persistent unconformities in rocks of proterozoic age in the western united states south australia and northwestern canada we conclude from these studies that the sequence stratigraphic approach is of considerable importance for intrabasinal time correlation in the proterozoic and for facies interpretation and basin analysis in proterozoic rocks

production and preservation of organic matter during deposition of the bakken formation late devonian and early mississippian williston basin abstract the organic rich up to 35 toc lower and upper black mudstone members of the bakken formation late devonian and early mississippian accumulated in response to both increased productivity and enhanced preservation that resulted from unique palaeogeographic palaeoceanographic and palaeoclimatic conditions during bakken deposition the semi isolated williston basin was located close to the equator 5 to 10 n in a zone of prevailing east to west winds a pattern of estuarine like marine circulation between the williston basin and open ocean conditions at the western craton edge of north america is proposed surface water discharged from the basin was replaced by nutrient rich deeper water sourced from the equatorial undercurrent in the pacific basin undercurrent flow into the williston basin upwelled providing a potentially sustainable source of nutrients to enhance productivity in the surface photic zone during black mudstone deposition in response to increased productivity that led to a high rate of organic sedimentation and quiescent deep water conditions due primarily to the geographic isolation of the basin and the restriction of estuarine like circulation to the upper water column anoxic bottom water developed on the basin floor as sea level rose during lower and upper black mudstone deposition anoxic bottom water expanded across the basin enhancing organic matter preservation conditions in the williston basin demonstrate that both increased productivity and improved preservation can be essential and complementary factors affecting organic rich mud deposition these results have potentially important implications for the accumulation of similarly organic rich deposits across the north american interior during late devonian and early mississippian time

combined tectonic sediment supply driven cycles in a lower carboniferous deep marine foreland basin moravice formation czech republic the lower carboniferous moravian silesian culm basin mscb represents the easternmost part of the rhenohercynian system of collision related deep water foreland basins culm facies the upper visean moravice formation mf of the mscb shows a distinct cyclic stratigraphic arrangement two major asymmetric megacycles bounded by basal sequence boundary each about 500 to 900 m thick have been revealed the megacycles start with 50 to 250 m thick basal segments of erosive channels overbank successions and slope apron deposits interpreted as lowstand turbidite systems up section they pass into hundred metre thick fine grained low efficiency turbidite systems palaeocurrent data show two prominent directions basin axis parallel ssw nne directions which are abundant in the whole mf and basin axis perpendicular to oblique w e to nw se directions which tend to be confined to the basal parts of the megacycles or channel lobe transition systems in their upper parts based on the facies characteristics palaeocurrent data sandstone composition data and trace fossil distribution data we suggest a combined tectonics sediment supply driven model for the mf basin fill periods of increased tectonic activity resulted in slope oversteepening probably combined with increased rate of lateral w e sediment supply into the basin producing the basal sequence boundary and the subsequent lowstand turbidite systems during subsequent periods of tectonic quiescence the system was filled mainly from a distant southern point source producing the thick low efficiency turbidite systems consistently with the previous models our own sediment composition data indicate a progressively increasing sediment input from high grade metamorphic and magmatic sources up section most probably related to an uplift in the source area and progressive unroofing of its structurally deeper crustal parts the first occurrence of the cruziana nereites ichnofacies in sand rich turbidite systems in the youngest parts of the mf go el to go spi zone supported by rapidly increasing quartz concentrations in sandstones is thought to indicate a transition from generally underfilled to generally overfilled phase in evolution of the mscb basin this transition may be linked to the onset of upper visean phase of northward basin fill progradation assumed by previous authors

oxygen isotope and mg ca composition of late visean mississippian brachiopod shells from sw iberia palaeoclimatic and palaeogeographic implications in northern gondwana abstract latest visean brachiopod shells gigantoproductus sp from the pedroches basin of sw spain were sampled in order to obtain chemical and isotopic evidence that may help first to assess if primary geochemical and isotopical signals are preserved in these shells and second to reconstruct temporal variations in palaeoceanographic and palaeoclimatic conditions in northern gondwana during this time span microtexture cathodoluminescence cl and ultrastructure under sem of the brachiopods were examined to avoid sampling of shell portions altered after deposition shell portions classified as non luminescent nl and non luminescent to slightly luminescent nl sl present geochemical signatures within the ranges considered normal for recent brachiopods that have not undergone significant diagenetic modification these include low to undetectable fe and mn contents high sr values and 18o values similar to those of carbonates in equilibrium with seawater on the other hand valve areas that are luminescent l or moderately luminescent with luminescent portions ml l present higher fe and mn contents lower sr concentrations and lower 18o values than those corresponding to nl and nl sl shells this suggests a greater diagenetic alteration of these portions and that they acted as microzones of reaction with the diagenetic fluids temporal trends through the studied interval show a spread in 13c values much lower than that observed for contemporaneous samples up to 1 6 thus obscuring the 13c global signal at the time scale resolution of this study in contrast the 18o record of brachiopod calcite 18oc shows an overall increase of 1 relative to v pdb from the oldest to the youngest samples this is accompanied by a 30 decrease in mg ca ratios of the brachiopod calcites confirming that at least part of this shift in 18oc was related to cooling combination of mg ca and 18oc proxies established in this paper although not full proof for brachiopods yet allowed for the calculation of a temperature drop of 3 3 c and a change in seawater 18ow that becomes 0 4 more positive during this interval the data are consistent with regional seawater cooling that accompanied an increase in continental ice volume over a relatively short time period of

a positive c isotope excursion induced by sea level fall in the middle capitanian of south china abstract a new carbon isotope excursion was recovered from the capitanian marine carbonates at the rencunping rcp section of south china significantly a pronounced excursion with elevated 13ccarb values over 5 was coeval with the conodont jinogondolella prexuanhanensis zone and resembles the kamura event recorded in tethys the excursions in 13ccarb constrained by conodont biostratigraphy however present inconsistent carbon cycle behaviors especially between the separated basins in south china and evidently reflect regional litho facies controls in addition a transitional environment in association with a fall in sea level was recovered from deposits of anoxic cherty carbonates subsequent to shallow water carbonates around the positive excursion in 13ccarb accordingly instead of this being a signal of global scale climatic cooling we suggest that the positive excursion in 13ccarb can be attributed to eutrophication effects regionally along a continental shelf in this scenario the increasing dissolved o2 level in the mixing zone that induced by the initial sea level fall will efficiently impede denitrification and increase the bio available n in n p ratio to satisfy the demands of primary producers in surface waters subsequently deposits of shallow water carbonates comprising calcareous algae and massively bedded lime muds accumulated widely around south china these deposits appear to represent an unusual environment and ecosystem fertilized perhaps by the weathering products from the earliest stages of volcanism prior to the main emeishan flood basalt eruptions at the guadalupian lopingian boundary glb

cyclic patterns in the paleozoic and mesozoic implications for time scale calibrations the analysis of both physical and biological data from the devonian strata of new york state reveals the existence of two robust cyclic patterns one cycle with a duration of 4 5 5 7 m y and a larger cycle of approximately twice this wavelength at 11 3 13 6 m y depending upon the absolute time scale used in the wavelength calculation the analysis of sedimentation rates from the jurassic likewise reveals a cycle with a temporal spacing of 4 to 6 m y a cycle with a periodicity virtually identical to the shorter cycle detected in the devonian the data further suggest the existence of cycles at 2 3 m y and 30 m y intervals though these periodicities approach the lower and upper limits of resolution of the data base the potential correlation of cyclic patterns has considerable implication for the development of new chronological time scales and global chronostratigraphic resolution current radiometric time scales have a resolution which is still above the stage level for most of the pre cenozoic in estimating the ages of stage boundaries most time scales are based on either the assumption of equal stage durations or the assumption of equal biostratigraphic zone durations and the subsequent linear interpolations between control tie points operating under the working hypothesis that a regular periodic signal exists in the data the above listed devonian cycles are brought into a more uniform periodicity by transforming the time scale itself yielding an alternatively calibrated timescale which is neither equal stage nor equal zone in structure

sequences cycles and basin dynamics in the silurian of the appalachian foreland basin abstract field stratigraphic analysis of the early and medial silurian strata of ontario new york and pennsylvania permits recognition of six major sequences reflecting 3rd order cycles in the niagaran llandoverian ludlovian of new york and adjacent regions these sequences correspond approximately to the medina lower clinton middle clinton upper clinton two sequences and lockport groups each is bounded by widespread unconformities produced by the interplay of eustatic sea level drop and local tectonic uplift in general erosional sequence boundaries and transgressive surfaces are merged with no record of the lowstand wedge each sequence is subdivisible into two to five sub sequences that are marked by sharp though generally non erosional basal discontinuities investigation of the clinton and lockport groups corroborates earlier suggestions that carbonate and siliciclassic tongues extended basinward from opposite margins synchronously in response to sea level drops analysis of the thickness and basinward extent of the progradational tongues reveals the existence of multi scale sedimentary cycles sequences and component sub sequences are correlative basinwide and are synchronous within the resolution of bio and event stratigraphy major drops in relative sea level are represented by the sequence bounding discontinutiies these surfaces are overlain by siliciclastic wedges near terrigenous source areas or winnowed carbonate pack and grainstones on the tectonically passive margin overlying highstand deposits typically shales calcareous mudstones and limestones are separated from lowstand or transgressive deposits by thin condensed intervals commonly marked by phosphatic or glauconitic material and or surfaces of maximum sediment starvation the relative highstand deposits of sequences and sub sequences are developed in relatively deep water facies and are at most slightly progradational hence most sequences and sub sequences are sharply bounded roughly upward deepening to slightly shallowing successions of strata in turn sub sequences are further divisible into widespread minor parasequences and parasequence sets probably corresponding to 6th and 5th order cycles respectively the smaller scale units 0 2 5 mthick commonly display an upward shallowing motif the nested relationship of these cycles supports the hierarchical model of transgressive regressive allocycles proposed by busch and rollins 1984 niagaran cycles discussed herein are equivalent to third fourth and fifth order cycles and are traceable circumbasinally depocenters of successive sequences and sub sequences display a pattern of eastward westward eastward basin axis migration through the silurian during early llandoverian the taconic queenston deltaic complex began to subside and the basin axis depocenter and eastern shoreline shifted eastward approximately 200 km over a 6 million year period as the basin axis migrated eastward the western basin ramp forebulge was repeatedly upwarded and eroded resulting in the generation of regionally angular unconformities at the bases of sequences ii iv and vi the pattern of unconformity greatest to the west suggests rise of the algonquin arch concomitant with eastward basin axis migration during the late llandoverian to early wenlockian the algonquin arch subsided slightly concurrently with a reversal in direction of basin axis migration during deposition of upper clinton and lockport vernon strata sequences v vi the basin axis shifted approximately 300 km back to the west eastward migration of the basin axis corresponds with a time of tectonic quiescence and probable thrust load relaxation the abrupt reversal of migration in the late llandoverian may be a signal of renewed thrusting in the hinterland at the onset of the salinic disturbance

persistence of a kelvin helmholtz instability complex in the upper troposphere 1 during the period of 7 14 september 1998 a multiple instrument campaign was conducted at the jicamarca radio observatory jro near lima peru using a 50 mhz vhf radar and radiosondes in this paper we discuss the radar and in situ observations and interpret them with insight gained from high resolution numerical simulations of the kelvin helmholtz instability khi evidence is presented that a large scale shear in the upper troposphere on 8 september 1998 becomes locally unstable due to ambient gravity wave activity isolated khi events result and subsequently grow and merge to form a large 3 km mixing layer a 3 km deep potential temperature step is observed at the same altitude at least a full day after the initial observations analysis indicates that neither turbulent mixing nor radiative cooling is capable of destroying the fully developed temperature step in the 21 hours available which lends credence to the hypothesis that the structure persisted for this period of time alternately the structure could be continuously generated by a standing wave associated with mountain wave forcing

the magnitude of late paleozoic glacioeustatic fluctuations a synthesis a comprehensive literature review shows that the magnitude of eustatic fluctuations varied throughout the carboniferous and permian and that at least eight distinct phases can be recognized facies juxtapositions in carbonate successions and erosional relief in clastic successions indicate that glacioeustatic fluctuations of 20 25 m and occasionally as much as 60 m took place throughout the early mississippian tournaisian a widely recognized glacial period middle mississippian mid chadian through holkerian shallow marine carbonate and clastic successions indicate that eustatic fluctuations were 10 25 m a decrease that matches well with the paucity of coeval glacial deposits late visean asbian through mid brigantian glacioeustatic fluctuations of 10 50 m record the initial phases of ice accumulation in advance of the widespread mid carboniferous glacial event the latest mississippian earliest pennsylvanian mid brigantian through langsettian was a time of widespread glaciation and strata of this age commonly exhibit evidence of glacioeustatic fluctuations of as much as 40 100 m although middle pennsylvanian duckmantian through asturian glacial deposits are present in eastern australia paleovalley depths suggest that coeval glacioeustatic fluctuations were less than 40 m glacioeustatic fluctuations of as much as 100 120 m have been widely reported from late pennsylvanian earliest permian stephanian through mid sakmarian successions in north america an increase that corresponds to the growth of large ice sheets across much of gondwana and the accumulation of ice in the northern hemisphere incision and facies juxtaposition in early middle permian mid sakmarian through kungurian successions in eastern australia indicate that glacioeustatic fluctuations of 30 70 m occurred during the waning stages of major glaciation erosional relief in paleoequatorial carbonates and the presence of coeval glacial deposits in australia suggests that eustatic fluctuations of 10 60 m occurred during the final stages of glaciation in the middle to late permian roadian through capitanian but the modest size of most of these fluctuations makes it difficult to isolate the glacioeustatic signature this review demonstrates that far field cyclic successions record changing glacial conditions in gondwana that the magnitude of glacioeustatic fluctuations was directly related to the volume of glacial ice that carboniferous permian glacioeustasy was more variable than previously recognized and that generalizations from short temporal intervals are probably not representative of the late paleozoic ice age as a whole although any attempt to quantify the magnitude of ancient eustatic changes is based on caveats and assumptions this review incorporates the results of over 100 published papers on the topic in an attempt to minimize the errors inherent in any one study

sedimentary cycles and paleogeography of the dnieper donets basin during the late visean serpukhovian based on multiscale analysis of well logs abstract an integrated approach combining the available geological geophysical information was employed to construct a series of paleogeographic maps of the northwestern part of the dnieper donets basin ddb during the late visean serpukhovian early carboniferous the major source of information consists of well log data the basin fill shows a pattern of stacked transgressive regressive units of different order correlations on the scale of the basin are based on biostratigraphy seismics cyclostratigraphic subdivisions and correlations of the successions throughout the basin the cyclicity has a multifold character short shallowing upward transgressive regressive t r cycles characterized by the presence of hydrocarbons productive horizons cover a time span of the order of 500 ka long cycles include 4 to 6 short t r cycles they seem to be correlatable to western europe and probably to north america the long cycles form part of higher order stacking patterns indicative of still longer cycles considering the variable thickness of the cycles throughout the basin tectonics must have influenced the character of the series in addition to glacio eustatic sea level fluctuations the paleogeographical development of the basin shows axial deposition during the late visean likely related to late stage rifting related subsidence of a central graben followed by basin wide subsidence related to thermal subsidence during the serpukhovian

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

how global are the jurassic cretaceous unconformities the reality of the global scale sedimentation breaks remains controversial a compilation of data on the jurassic cretaceous unconformities in a number of regions with different tectonic settings and character of sedimentation where new or updated stratigraphic frameworks are established permits their correlation unconformities from three large reference regions including north america the gulf of mexico and western europe were also considered the unconformities which encompass the jurassic cretaceous the lower upper cretaceous and the cretaceous palaeogene transitions are of global extent other remarkable unconformities traced within many regions at the base of the jurassic and at the santonian campanian transition are not known from reference regions a correlation of the jurassic cretaceous global scale sedimentation breaks and eustatic curves is quite uncertain therefore definition of global sequences will not be possible until eustatic changes are clarified activity of mantle plumes is among the likely causes of the documented unconformities

comment on paleokarst on the top of the maokou formation further evidence for domal crustal uplift prior to the emeishan flood volcanism a department of geoscience 121 trowbridge hall university of iowa iowa city ia 52242 usa b biogeoscience queensland university of technology brisbane queensland 4001 australia c department of earth and environment university of leeds leeds ls2 9jt uk d dougalearth ltd 12 nevilles cross villas durham dh1 4jr uk e department of earth sciences university of hong kong pokfulam road hong kong china

radio occultation measurements of pluto s neutral atmosphere with new horizons abstract on 14 july 2015 new horizons performed a radio occultation ro that sounded pluto s atmosphere down to the surface the sensitivity of the measurements was enhanced by a unique configuration of ground equipment and spacecraft instrumentation signals were transmitted simultaneously by four antennas of the nasa deep space network each radiating 20 kw at a wavelength of 4 2 cm the polarization was right circular for one pair of signals and left circular for the other pair new horizons received the four signals and separated them by polarization for processing by two independent receivers each referenced to a different ultra stable oscillator the two data streams were digitized filtered and stored on the spacecraft for later transmission to earth the results reported here are the first to utilize the complete set of observations we calibrated each signal to remove effects not associated with pluto s atmosphere including the limb diffraction pattern we then applied a specialized method of analysis to retrieve profiles of number density pressure and temperature from the combined phase measurements occultation entry sounded the atmosphere at sunset at 193 5 e 17 0 s on the southeast margin of an ice filled basin known informally as sputnik planitia sp occultation exit occurred at sunrise at 15 7 e 15 1 n near the center of the charon facing hemisphere above 1215 km radius 25 km altitude there is no discernible difference between the measurements at entry and exit and the ro profiles are consistent with results derived from ground based stellar occultation measurements at lower altitudes the ro measurements reveal horizontal variations in atmospheric structure that had not been observed previously and they are the first to reach the ground the entry profile has a strong temperature inversion that ends 3 5 km above the surface and the temperature in the cold boundary layer beneath the inversion is nearly constant 38 9 2 1 k and close to the saturation temperature of n 2 the exit profile has a much weaker inversion that extends all the way to the ground where the air temperature is 51 6 3 8 k three factors appear to be responsible for the presence of a cold boundary layer in the entry profile forget et al 2017 a substantial diurnal cycle of sublimation and condensation of n 2 ice in sp the local time of the ro observation and confinement within sp by the surrounding topography and katabatic winds we have also determined the surface pressure and the local radius at both entry and exit the best pressure reference is the mean value 11 5 0 7 microbar at 1189 9 0 2 km