late paleozoic glacial episodes in gondwanaland reflected in transgressive regressive depositional sequences in euramerica the late paleozoic glaciation of gondwanaland comprised two short episodes in the famennian i and visean ii confined to brazil and adjacent northwest africa and a long episode that started in the namurian iiia of eastern australia and bolivia argentina expanded to cover much of gondwanaland in the stephanian asselian iiib and collapsed in the early sakmarian iiic dropstones in eastern australia indicate that small ice centers lingered to the kazanian across the belt of low latitudes north of gondwanaland short ranging fossils in widespread shallow marine and paralic deposits indicate synchronous deposition of transgressive regressive sequences in different parts of euramerica these sequences correlate with glacial events in gondwanaland at three levels a four major regressions in euramerica in the famennian 1 visean 2 namurian 3 stephanian 4 and the tastubian transgression that preceded the sterlitamakian regression 5 also recorded in gondwanaland correlate with glacial episodes i ii and iiia iiib and iiic b the time interval of cyclothemic deposition in euramerica brigantian or latest visean to sterlitamakian correlates with that of glacial episode iii and c the dominant period of the euramerican cyclothems as estimated from the middle and late pennsylvanian deposits of the mid continent of north america and of the thickest known gondwanaland glacigenic sediment the earliest permian lyons group of western australia is 0 4 ma equivalent in turn to the long orbital eccentricity period of the quaternary ice age and the dominant period of fluctuation of the late miocene antarctic ice cap the three levels of correlations confirm wanless and shepard9s 1936 hypothesis that the late paleozoic cyclothems are controlled largely by sea level fluctuations related to the gondwanaland glaciation

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

high resolution sequence stratigraphy of the late namurian in the widmerpool gulf east midlands uk abstract analysis of facies stacking patterns and stratal surfaces within late namurian deltas of the widmerpool gulf has revealed 10 high frequency fourth order depositional sequences sequence correlation is based on the characteristic marine band fauna of their condensed sections in many instances sequence boundaries are difficult to recognize unless there is clearly demonstrable lowstand incision consequently it is often difficult to separate late highstand from falling stage progradation with any degree of confidence sequence thickness variations and the dominance of particular stratal surfaces and systems tracts were controlled by a longer period third order cycle of relative sea level rise and fall during the marsdenian yeadonian major fluvio deltaic sand bodies in the widmerpool gulf were formed by distributary channel progradation e g chatsworth grit during the late highstand and or falling stage systems tracts and by the filling of incised valleys e g ashover grit and rough rock following marked sea level falls channel belt and valley fill orientation was initially influenced by differential compaction but this influence decreased during the late namurian the recognition of incised valley fills within the late namurian has implications for estimating the magnitudes and periodicities of carboniferous relative sea level change

nature and timing of late mississippian to mid pennsylvanian glacio eustatic sea level changes of the pennine basin uk discussion reply although we appreciate that the points made by bailey are relevant to any discussion of interpreting stratigraphic patterns as being astronomically paced we take this opportunity to discuss the details of the carboniferous of the pennine basin beyond simple rock thickness time concepts or models and reiterate points relevant to the conclusions of waters condon 2012 namely the nature of the expression of sea level variation within the carboniferous pennine basin and its regional and global geological context at the heart of the comment by bailey is our assertion that glacio eustatic sea level change as a response to milankovitch forcing was a first order control on the repeated marine flooding events in late mississippian to mid pennsylvanian stratigraphy of the pennine basin uk it has been proposed by numerous researchers acknowledged by waters condon 2012 that the cyclicity evident within the pennine basin

on the periodicity and magnitude of late carboniferous glacio eustatie sea level changes data from sedimentary cycles in basins from northern england the appalachians and midcontinent us afford an insight into periodicities and controls of late carboniferous glacio eustatic sea level changes lithofacies with identifiable palaeobathymetry are used to assess the magnitude of sea level change in the pennine basin of northern england the method yields a minimum value of 42m walsh power spectral analysis is employed to resolve periodicities of about 120ka within the pennine basin of northern england 212 140 and 93 ka within the midcontinent us succession and 109 84 67 63 ka within the appalachian basin within the pennine basin periodicities and magnitudes are found to be independent of their position within the basin thus any tectonism can be assumed to have had a negligible effect on the transgressions a simplified modelled climatic curve is derived from milankovitch parameters and pleistocene 18 o data this is used in a basin fill model that simulates the thermally subsiding pennine basin the resulting distribution of marine deposits is seen to depend upon both the steady regional subsidence and the magnitude and extent of glacio eustatic transgressions

sea level curve for pennsylvanian eustatic marine transgressive regressive depositional cycles along midcontinent outcrop belt north america at least 55 cycles of marine inundation and withdrawal are recognized in the mid desmoinesian to mid virgilian midcontinent outcrop sequence in north america they range from widespread major cycles classic cyclothems with deep water facies extending across the northern shelf through intermediate cycles persisting as marine horizons across the shelf to minor cycles developed on the lower shelf or as parts of major cycles biostratigraphic differentiation of the cycles should establish interbasinal correlation on a scale fine enough to allow evaluation of differential tectonics and sedimentation sequential groupings of cycles are more irregular than proposed megacyclothems or mesothems but they may be obscured by the distinctness of the major cyclothems estimates of cycle periods range from about 40 to 120 x 10 sup 3 yr for the minor cycles up to about 235 to 400 x 10 sup 3 yr for the major cyclothems the range for all cycles corresponds well to the range of periods of earth s orbital parameters that constitute the milankovitch insolation theory for the pleistocene ice ages and it further supports gondwanan glacial control for the pennsylvanian cycles even though the dominant period of the major pennsylvanian cyclothems is up to four times longer than the dominant 100 000 yr period inmore the pleistocene the shapes of both curves display rapid marine transgression rapid melting of ice caps and slow interrupted regression slow buildup of ice caps which suggest similar linkages between the climatic effects of the orbital parameters and ice cap formation and melting at the two different scales widely separated in time 28 references 3 figures less

uk onshore oil exploration 1930 1964 abstract the earliest attempts to find oil in britain dating from 1918 1922 based on anticlines flanking the pennines were largely unsuccessful renewal of exploration in the 1930s aimed at a broader range of prospects met with much criticism but went ahead after nationalization of the unknown and undiscovered oil resources 1934 the south of england ranked as first priority but the initial drilling of the new campaign carried out in 1935 1937 yielded only minor quantities of oil and gas attention was transferred in 1938 to upper palaeozoic prospects in the midlands and north resulting in small gas and oil discoveries in scotland and yorkshire and discovery of a series of commerical oilfields in the upper carboniferous of nottinghamshire in the 1950s the first commercial discovery in the jurassic was made at kimmeridge in dorset further carboniferous discoveries were made in nottinghamshire and lincolnshire and a series of fresh objectives defined by seismic reflection were drilled in the mesozoic basin of southern england this phase of exploration was terminated at the end of 1964 by adverse fiscal changes continuation of effective exploration operations remained uneconomic until the oil price rise in 1973

estimating carboniferous sea level fluctuations from gondwanan ice extent the magnitude of carboniferous sea level fluctuations is not well known but the estimates are important for constraining cyclothem models in this paper we apply area volume relations developed for quaternary ice sheets to estimate the glacio eustatic component of sea level fluctuations in the carboniferous utilizing the best estimate of gondwanan ice area at the time of its greatest extent we arrive at a figure of 60 15 m for the isostasy corrected glacio eustatic component this value is nearer the lower limit of sea level estimates for cyclothem fluctuations from other sources

geochemical and lithological controls on a potential shale reservoir carboniferous holywell shale wales the holywell shale is part of the carboniferous bowland shale formation identified as the main potential shale gas system in the uk here we report geochemical and petrographic data from five outcrops of the lower and upper holywell shale across northeast wales at outcrop the holywell shale is immature to early oil mature and has total organic carbon toc values ranging between 0 1 and 10 3 wt with a mean of 1 9 wt carbon isotope data clearly differentiate terrestrial and marine organic matter and show that both occur throughout the holywell with terrestrial sources type iii iv dominating the upper holywell and marine sources dominating the lower holywell type ii iii trace element data indicate that bottom waters were oxygenated resulting in poorly preserved organic matter supported by c n and hi data a range of silt and clay rich lithofacies occur which show no relationship to either the amount or type of organic matter we interpret the data in terms of a mixed supply of terrestrial and marine organic matter to marine depositional environments in which there was sufficient hydrodynamic energy to transport fine grained sediment as bed load the resulting mudstones exhibit a range of sedimentary textures with millimetre to centimetre scale silt clay bed forms which show almost no relationship to organic matter type and amount the small scale variability and heterogeneity of both organofacies and lithofacies means that the reservoir quality of the holywell shale is inherently difficult to predict

sedimentary process control on carbon isotope composition of sedimentary organic matter in an ancient shallow water shelf succession 1 source and delivery mechanisms of organic matter are rarely considered when interpreting changing 13c through sedimentary successions even though isotope excursions are widely used to identify and correlate global perturbations in the carbon cycle combining detailed sedimentology and geochemistry we demonstrate how organic carbon abundance and 13c values from sedimentary organic matter from carboniferous aged mudstones are influenced by the proportion of terrestrial versus water column derived organic matter silt bearing clay rich shelf mudstones that were deposited by erosive density flows are characterized by 1 8 2 4 organic carbon and high 13c values averaging 22 9 0 3 n 12 typically these mudstones contain significant volumes of terrestrial plant derived material in contrast clay rich lenticular mudstones with a marine macrofauna are the products of the transport of mud fragments eroded from pre existing water rich shelfal muds when shorelines were distant and biological productivity in the water column was high higher organic carbon 2 1 5 2 and lower 13c values averaging 24 3 0 5 n 11 characterize these mudstones and are interpreted to reflect a greater contribution by isotopically more negative amorphous organic matter derived from marine algae differences in 13c between terrestrial and marine organic matter allow the changing proportions from different sources to be tracked through this succession combining 13c values with zirconium measured from whole rock here used as a proxy for detrital silt input provides a novel approach to distinguishing mudstone provenance and ultimately using 13c to identify oil prone organic matter in potential source rocks these results have important implications for using bulk organic matter to identify and characterize global c isotope excursions

forced regressions in a sequence stratigraphic framework concepts examples and exploration significance sequence stratigraphic concepts suggest that stratal geometries develop and are largely controlled by changes in relative sea level on the shelf lowstand deposits which form during falls and subsequent stillstands of relative sea level can be recognized by the presence of an unconformity at the base the isolated and basinward position relative to the previous shoreline and the abrupt seaward translation of shallow water and shoreline facies into the basin across an unconformity surface this seaward translation of facies and shoreline regression in response to relative sea level lowering is termed a forced regression a forced regression is independent of variations of sediment flux and is in contrast with normal regressions that occur in response to excess sediment flux relative to space available on the shelf i e accommodation forced regressions commonly are associated with a zone of sedimentary bypass subaerial exposure and possible fluvial erosion between the newly formed and preceding shorelines certain shelf sands previously interpreted as offshore or mid shelf sand bodies thus can be reinterpreted as stranded lowstand shorelines associated with forced regressions this alternative interpretation has economic significance insofar as it suggests different subsurface correlations and reservoir geometries with the potential for development of new play types and enhanced recovery in o der fields examples of forced regression can be observed at a variety of scales and ages several such examples include the modern east coulee fan delta and the lower cretaceous viking formation in alberta canada the quaternary rhone delta and the quaternary hudson valley system

sequence stratigraphy of coastal alluvial plain westphalian b coal measures in northumberland and the southern north sea abstract westphalian b coastal alluvial plain coal measures of northumberland and the southern north sea are susceptible to stratigraphic base level fluctuations of various magnitudes which create a hierarchy of flooding surfaces 1 high magnitude third order maximum flooding surfaces corresponding to the anthracoceratites vanderbeckei and anthracoceras aegiranum marine bands defining the top and bottom of the succession when vast areas of the westphalian foreland basin were flooded by marine incursions 2 high frequency fluctuations promoting small scale fourth order flooding of the entire or large areas 100 s km 2 of the alluvial plain resulting in deposition of non marine bivalve beds or marine bands depending on their position on the third order base level curve and 3 small scale localised base level rises due to differential compaction and autocyclic switching of minor crevasse splays and distributary channels a regionally extensive third order tectonically induced sequence boundary is also recognised in the southern north sea slightly above the maximum stand in stratigraphic base level recorded by the vanderbeckei marine band this sequence boundary which represents the lowest point on the background eustatic base level curve between the two maximum flooding surfaces is overlain by the multilateral multistorey caister sandstone the lack of significant erosional relief beneath this channel sandstone suggests that accommodation space at this time was being created at a very low rate the succession above the caister sandstone sequence boundary up to the aegiranum marine band maximum flooding surface records an increasing rate of stratigraphic base level rise this equates to a third order transgressive systems tract or sequence set comprising a number of fourth order sequences which change upwards in response to the background low frequency rise the increasing rate of base level rise and increased accommodation space is accompanied by a change in fluvial style to more isolated channels enclosed within floodplain deposits

a high resolution simulation of convective roll clouds during a cold air outbreak 1 a ubiquitous feature of the high latitude ocean is the occurrence of convective clouds that are organized into two dimensional structures known as roll clouds or cloud streets in this paper we present a simulation of these structures that was performed in a domain large enough to simulate numerous roll clouds and their downstream evolution at a resolution sufficient to resolve the individual convective clouds the simulations were initialized and validated using observations of roll clouds over the labrador sea the model results indicate that the secondary flow associated with the roll clouds results in significant differences in the temperature humidity and momentum fields between the updrafts and downdrafts the model was also able to reproduce the observed downstream evolution of the clouds as the organization of the convection changed from two dimensional rolls to three dimensional closed cells

transgressions and regressions a model for the influence of tectonic subsidence deposition and eustasy with application to quaternary and carboniferous examples the position of a coastline in time and space is determined by 1 the vertical displacement and or tilting of the depositional surface 2 the rate of sediment accumulation or erosion across that surface and 3 variation of sea level all three rates of change may vary through time we present computer simulations of coastline movements that illustrate the interaction of the above variables with 1 and 2 held at various defined levels whilst 3 is varied according to the late quaternary glacio eustatic sea level curve the corinth canal section in central greece exposes uplifted late quaternary coastal transgressive cycles each of which may be related to a radiometrically dated c 100 ka duration cycle of sea level change observed stratigraphic sequence geometries are predicted by forward modelling based on the known glacio eustatic history over the last 430 ka milankovitch orbital parameters are calculated for the carboniferous period the obliquity and precession parameters are found to have been significantly shorter than at present a simulation is presented of the effects of sea level changes across low gradient fluvio deltaic environments such as existed in northern england and other parts of the laurentian continental margin during upper carboniferous time

sulfur geochemistry of hydrothermal waters in yellowstone national park i the origin of thiosulfate in hot spring waters thiosulfate s sub 2 o sub 3 sup 2 minus polythionate s sub x o sub 6 sup 2 minus dissolved sulfide h sub 2 s and sulfate so sub 4 sup 2 minus concentrations in thirty nine alkaline and acidic springs in yellowstone national park ynp were determined the analyses were conducted on site using ion chromatography for thiosulfate polythionate and sulfate and using colorimetry for dissolved sulfide thiosulfate was detected at concentrations typically less than 2 micro mol l in neutral and alkaline chloride springs with low sulfate concentrations cl sup minus so sub 4 sup 2 minus 25 the thiosulfate concentration levels are about one to two orders of magnitude lower than the concentration of dissolved sulfide in these springs in most acid sulfate and acid sulfate chloride springs cl sup minus so sub 4 sup 2 minus 10 thiosulfate concentrations were also typically lower than 2 micro mol l however in some chloride springs enriched with sulfate cl sup minus so sub 4 sup 2 minus between 10 and 25 thiosulfate was found at concentrations ranging from 9 to 95 micro mol l higher than the concentrations of dissolved sulfide in these waters polythionate was detected only in cinder pool norris geyser basin at concentrations up to 8 micro mol l with an average s chain length from 4 1 to 4 9 sulfur atoms the results indicate that no thiosulfate occurs in the deeper parts of themore hydrothermal system thiosulfate may form however from 1 hydrolysis of native sulfur by hydrothermal solutions in the shallower parts 50 m of the system 2 oxidation of dissolved sulfide upon mixing of a deep hydrothermal water with aerated shallow groundwater and 3 the oxidation of dissolved sulfide by dissolved oxygen upon discharge of the hot spring upon discharge of a sulfide containing hydrothermal water oxidation proceeds rapidly as atmospheric oxygen enters the water the transfer of oxygen is particularly effective if the hydrothermal discharge is turbulent and has a large surface area less

sequence stratigraphy of the upper yeadonian of northern england abstract a detailed study of an upper namurian cyclothem is presented the upper yeadonian basin fill of the pennine basin consists of three deltaic sandstones interbedded with mudstones of a variety of facies the cyclothem is a fourth order cycle representing deposition over a period of a few hundred thousand years the results of the study in terms of sediment accumulation patterns are investigated using the exxon sequence stratigraphic model in addition a simple computer model is presented to illustrate idealized pennine sedimentary fill in a one dimensional succession multiple condensed sequences at the base of cyclothems form part of a transgressive systems tract the succeeding fluvio deltaic facies are interpreted as part of a highstand systems tract the latest yeadonian rough rock sandstone is interpreted as a possible lowstand wedge a high resolution relative sea level curve is also presented for the late yeadonian

fluvial channel and overbank deposits from the westphalian of the durham coalfield ne england the westphalian upper carboniferous coal measures of the durham coalfield in ne england were deposited in lower and upper delta plain environments distributary channels crossed the plain and were separated by shallow interdistributary lakes and bays detailed observation of three dimensional 3 d opencast surface mine exposures in collaboration with subsurface borehole analysis has revealed the existence of five varieties of channel deposits and two associated overbank facies within the durham coal measures major distributary channels were the major avenues of sediment transport across the coal measures plain were variably sinuous mostly 1 2 km wide and deposited elongate belts of sand mostly up to 5 km wide proximal major crevasse splay channels formed by the breaching of major channel banks during flood events were straight sand filled and up to 400 m wide minor distributary channels formed by the sustained operation of such crevasses varied from straight to highly sinuous and deposited shoestring sand mud belts up to a few hundred metres wide minor crevasse channels generally straight and up to 50 m wide were formed through bank breaching of minor and in a few cases major distributaries distal feeder channels formed down palaeocurrent extensions of minor distributaries which supplied interdistributary minor delta subsystems were generally straight and up to 200 m wide of the two types of channel overbank levee deposits recognized one comprising thinly interbedded fine grained sandstone and siltstone claystone is mostly though not exclusively associated with major distributary channels the other consisting of massive siltstones with regularly spaced thin claystone bands is uniquely developed at the margins of minor distributary channels the lower part of the westphalian a succession in the northern pennines records a change in the depositional environment upwards from a lower to upper delta plain through this transition major channel deposits show evidence of having evolved from being of dominantly low sinuosity to being more variable in morphology channel sedimentation was profoundly influenced by regular possibly seasonal variations in flow stage and sediment load

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

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr