magnetostratigraphic constraints on the age of the lower beaufort group western karoo basin south africa and a critical analysis of existing u pb geochronological data we studied three partially overlapping sections with a composite thickness of 600 m in the upper permian fluvial siltstones and fine grained sandstones of the abrahamskraal formation the basal unit of the beaufort group in the karoo basin of western cape province south africa paleomagnetic analysis reveals three components of natural remanent magnetization nrm heating to 180 c removes a remanent magnetization parallel to the present day field which is interpreted as a viscous overprint an intermediate unblocking temperature component is removed by heating to 450 c this direction is always of normal polarity and is identical to a regional overprint imparted during the early jurassic emplacement of the karoo large igneous province a high temperature component isolated above 450 c is of dual polarity and is interpreted as primary on the basis of a positive reversals test the virtual geomagnetic pole position for the abrahamskraal formation computed from the average high temperature characteristic remanent magnetization direction is in agreement with the late permian directions for stable gondwana and with previous results from the lowermost abrahamskraal formation and waterford formation at the ouberg pass section the predominantly normal polarity of this magnetization is in agreement with either a middle late lopingian age ca 254 256 ma or a late guadalupian age ca 262 ma according to the global geomagnetic polarity time scale we integrate these new results with existing magnetostratigraphic biostratigraphic and geochronological results from the karoo basin with particular emphasis on the controversy over zircon age data reported from the underlying ecca group

middle late permian mass extinction on land the end permian mass extinction has been envisaged as the nadir of biodiversity decline due to increasing volcanic gas emissions over some 9 million years we propose a different tempo and mechanism of extinction because we recognize two separate but geologically abrupt mass extinctions on land one terminating the middle permian guadalupian at 260 4 ma and a later one ending the permian period at 251 ma our evidence comes from new paleobotanical paleopedological and carbon isotopic studies of portal mountain antarctica and comparable studies in the karoo basin south africa extinctions have long been apparent among marine invertebrates at both the end of the guadalupian and end of the permian which were also times of warm wet greenhouse climatic transients marked soil erosion transition from high to low sinuosity and braided streams soil stagnation in wetlands and profound negative carbon isotope anomalies both mass extinctions may have resulted from catastrophic methane outbursts to the atmosphere from coal intruded by feeder dikes to flood basalts such as the end guadalupian emeishan basalt and end permian siberian traps

quantifying global warming from the retreat of glaciers records of glacier fluctuations compiled by the world glacier monitoring service can be used to derive an independent estimate of global warming during the last 100 years records of different glaciers are made comparable by a two step scaling procedure one allowing for differences in glacier geometry the other for differences in climate sensitivity the retreat of glaciers during the last 100 years appears to be coherent over the globe on the basis of modeling of the climate sensitivity of glaciers the observed glacier retreat can be explained by a linear warming trend of 0 66 kelvin per century

contribution of small glaciers to global sea level observed long term changes in glacier volume and hydrometeorological mass balance models yield data on the transfer of water from glaciers excluding those in greenland and antarctica to the oceans the average observed volume change for the period 1900 to 1961 is scaled to a global average by use of the seasonal amplitude of the mass balance these data are used to calibrate the models to estimate the changing contribution of glaciers to sea level for the period 1884 to 1975 although the error band is large these glaciers appear to account for a third to half of observed rise in sea level approximately that fraction not explained by thermal expansion of the ocean

the development of brittle structures in an alpine valley glacier pasterzenkees austria 1887 1997 brittle structures exposed in the ablation area of pasterzenkees austria were interpreted using aerial photographs and maps covering a period of 100 years the most common structural features observed in aerial photographs are 1 normal faults which are particularly well developed along the lateral margins of the glacier and at the terminus 2 large scale tension gashes and riedel shears that develop along the northeastern lateral margin of the glacier and between ice flow units 3 thrust faults which develop at the terminus and cross cut the full width of the glacier and 4 band ogives longitudinal and transverse topographic profiles are available for the period covered in this study and ice flow velocity data are available from 1927 these data provide a means for interpreting the variations of observed structures in terms of ice flow velocity thrust faults predominantly develop during periods of glacier retreat when the glacier snout becomes an obstacle normal faults typically develop in areas of high glacier surface relief and are interpreted as gravity collapse structures the orientation of sub vertical wide open crevasses along the lateral margin of pasterzenkees varied these variations are interpreted as reflecting changes of the flow regime and indicate a transition from simple shearing to transtension during a period of ice flow deceleration

macro and micro factors affecting coal seam quality and distribution in southern africa with particular reference to the no 2 seam witbank coalfield south africa abstract petrographical and palynological coal quality investigations relating to variations in one of the best known and well researched coalfields in africa the witbank coalfield and one of the most commercially important seams within this coalfield the no 2 seam are highlighted in this paper the investigations were based on 14 channel samples covering a 40 20 km 2 area in the witbank coalfield the results indicate that the coals in the no 2 seam were formed at the stage of major change over from dwyka to ecca floras as illustrated by the progressive dying out of dwyka pollens and spores and the introduction of ecca floral elements this also suggests a rapid amelioration of climate over the period of peat accumulation following a period of continental glaciation furthermore it is proposed that the in seam horizons reflect fluctuating of cyclic environments probably due to changing water level and plant communities due to changing growth environments saccate pollens appear to occur in association with vitrinite rich microlithotypes trilete spores with inertodetrite and carbominerite rich microlithotypes and plicates with inertite semifusite inertodetrite microlithotypes acritarchs nonspinose are present in parts of the seam where inertodetrite is common and in association with unusual suites of trace and major elements possibly indicating changing geochemical environments in high groundwater conditions petrographic results indicate that the coals are medium rank hypobituminous and show wide variations in maceral mineral and microlithotype compositions both vertically and laterally on the basis of microlithotype and mineral group analyses investigations were undertaken to establish vertical subdivisions by the study of historical patterns and possible lateral correlations of these subdivisions in the area under investigation these methods were then compared with distribution of selected chemical and geochemical parameters the evidence suggests that a common sequence of major events and some minor events occurred during the accumulation of the no 2 seam as manifested by petrographic and palynological facies three major periods or zones are recognized these tepresent periods of relatively stability quiescence separated by major in seam disruptive events namely flood deposits bearing high proportions of detrital organic material or minor clastic sedimentation these zones are subdivided into several subzones representing periods of reworking local flooding or rise in ground water levels and or changing geochemical environments these events can be recognized throughout the area under investigation but the manifestation of these events varies from area to area depending upon topographic situation proximity to river channels valley flanks or palaeoshorelines degree of subsidence and compaction geochemical environment and length of time under a specific set of conditions thus channels in close proximity to one another or in similar positions relative to valley flanks or axes appear to be remarkably similar to one another direct correlation of stratigraphic zones and sub zones from sample site of sample site was therefore possible although the methods to achieve this are complex and require the support of several supplementary complementary interpretative techniques coal quality variations and distribution within the original seam are therefore explicable in terms of the detailed factors listed above

palynofloral palynofacies and carbon isotope of permian coal deposits from the godavari valley coalfield south india insights into the age palaeovegetation and palaeoclimate abstract palynological studies of the present permian sediments play a vital role in biostratigraphic and palaeoecological interpretations additionally the palynofacies analysis total organic carbon toc content and 13c value in the present study focus largely for the palaeoenvironmental and palaeoclimatic reconstruction and also provides information about processes responsible for sedimentary deposits along with their lithological counter parts the palynological investigation of 306 m deep borehole msm 25 from the somavaram area of the godavari valley coalfield has led to infer five distinct palynofloral assemblages the artinskian palynofloral assemblage i and ii guadalupian palynofloral assemblage iii and iv and lopingian palynofloral assemblage v ages have been assigned to the palynofloral assemblages based on the palynofloral evidence the distinct stable carbon isotope ratios also comprehend these ages with extreme climatic events the artinskian age 22 4 is characterized by relatively higher average 13c values whereas lowest average 13c values are observed at the lopingian age 24 0 with intermediate average 13c value 23 2 during guadalupian age in the present study the permian triassic p t transition is marked by the distinct negative carbon isotope excursion followed by a distinct recovery during the early triassic time period the relative variability of palynofacies components such as palynomorphs structured terrestrial phytoclasts opaque phytoclasts degraded organic matter om and amorphous om is related to hydrodynamic perturbations during the deposition time based on the dominance and sub dominance of the palynofacies three distinct depositional phases have been identified representing differential environmental settings the palynomorphs and structured terrestrial phytoclasts dominate the palynofacies assemblage a suggesting forest swamp environment while in the palynofacies assemblage b the dominance of degraded om and amorphous om characterize reed marshes lakeshore setting and the abundance of opaque phytoclasts in the palynofacies assemblage c indicate oxidized swamp environment

palynological records of the permian ecca group south africa utilizing climatic icehouse greenhouse signals for cross basin correlations abstract the permian formations of the south african karoo basin play a crucial role in understanding gondwana s climate history during this time of major global changes in this paper we present two data sets one from the coal bearing vryheid formation witbank basin and one from the whitehill and upper prince albert formations of the dp 1 78 core ne karoo our main goal was to study the vegetation changes during this period of global warming and test if the climatic signals could be used to correlate the basinal ecca group facies with the fluvio deltaic coal bearing strata of the witbank basin the palynological record of the no 2 coal seam of the vryheid formation indicates a cold climate fern wetland community characteristic of lowland alluvial plains and an upland conifer community in the lower part of the coal seam up section these communities are replaced by a cool temperate cycad like lowland vegetation and gymnospermous upland flora the data set of the dp 1 78 core is interpreted to represent a cool to warm temperate climate represented by a high amount of gangamopteris and glossopteris elements both data sets are very different in their composition which can be explained by the differences in depositional environment however our findings reveal a different age of the studied assemblages and thus also suggest that both data sets represent different stages in the transition from icehouse to greenhouse during permian times as the stratigraphic correlation between the main karroo basin and the peripheral basins is still under discussion this paper provides new data to underpin the stratigraphic placement of the whitehill formation relative to the coal bearing vryheid formation

radiometric dating demonstrates that permian spore pollen zones of australia and south africa are diachronous abstract the well refined permian palynozonation of western and eastern australia is the current standard biostratigraphic scheme for the southern hemisphere but intra gondwanan floristic provincialism means that several stratigraphically useful palynomorph taxa are rare or absent elsewhere in gondwana radio isotopic ages for both australia and the main karoo basin of south africa demonstrate that key marker taxa appear diachronously in the two countries or they are absent in one of the countries the establishment of new plant taxa in the gondwanan permian realm was strongly tied to palaeolatitude with floral distributions primarily affected by temperature precipitation and seasonality this spatio temporal variation of floras hinders global biostratigraphic correlations both south africa and australia have excellent long ranging permo triassic terrestrial sedimentary successions and although vertebrate biostratigraphy has been the focus of much research endeavour in the south african karoo palynological studies have lagged accordingly a new south african palynozonation should be established that is based on the first appearances of key index taxa in the main karoo basin rather than elsewhere in gondwana in the interim the diachronous ranges of palynomorphs must be considered when correlating south african rocks to other global sections by means of the australian spore pollen zonation

controls on early permian shelf deglaciation in the karoo basin of south africa abstract the late carboniferous to early permian glacigene dwyka group has at its top three types of transitions from diamictite to postglacial mudrock in the southern karoo the type 1 transition sequence consists of clast poor carbonate rich diamictite having a sharp contact with the overlying mudrocks this diamicton accumulated slowly by rain out and sediment gravity flow processes during sedimentation the polar ice front was stabilised by a possible ice shelf collapse of the ice shelf caused rapid ice margin retreat the type 2 transition sequence consists of clast poor diamictite with sandstone bodies overlain by mudrock with ice rafted debris or thin interbedded debris flow diamictites deposition of the diamictite facies occurred during oscillations of a subpolar ice front with short stable periods of surface melting of the ice resulting in the formation of small subaqueous outwash fans the type 3 transition sequence consists of bouldery diamictite interbedded with massive or sandstone bearing diamictite overlain by mudrock with ice rafted debris or thin interbedded debris flow diamictites the sequence represents highly unstable ice front conditions and fluctuating sea levels with periods of rapid deposition probably by collapsing ice streams climatic conditions may have alternated between polar and subpolar the type 1 transition sequence is predominant in the western part and the type 3 sequence in the eastern part of the karoo basin long term controls on deglaciation was climatic warming as gondwana drifted over the pole as well as changes in land sea configuration superimposed on these were local controls such as relative sea level changes presence of deformable substrate and meltwater production

numerical modelling of past retreat and future evolution of chhota shigri glacier in western indian himalaya the history of glacier length fluctuations serves as a reliable indicator of the past climate in this paper a numerical flowline model has been used to study the relationship between length variations of chhota shigri glacier and local climate since 1876 the simulated front positions of chhota shigri glacier are in agreement with those observed after a successful simulation of the past retreat the model was also used to predict future evolution of the glacier for the next 100 years under different climatic scenarios these simulations indicate that the chhota shigri glacier may lose 90 of its present volume by 2100 if the local temperature increases by 2 4 k and for a temperature rise of 5 5 k the glacier loses almost all its volume

prevailing anoxia in the kungurian permian of south china possible response to divergent climate trends between the tropics and gondwana the kungurian ocean climate system has received little attention but a new compilation of geochemical and paleoclimatic proxies suggest more complex climate dynamics during the late paleozoic icehouse greenhouse transition than previously considered here integrated carbon isotope stratigraphical sedimentological and geochemical data across two early middle permian successions in the youjiang basin south china is presented these proxies indicate widespread anoxia below or near the water sediment interface in south china during the kungurian high primary productivity high sedimentation rate and a relative sea level rise are here proposed as being responsible for this process in the late kungurian but cannot account for the remaining anoxia at cycle boundaries we put forward a hypothesis that divergent climate trends between the tropics and gondwana might have played an important role in ocean stagnation and prevailing o2 deficient conditions in and probably outside south china during the kungurian the termination of anoxia in this region during the latest kungurian is attributed to an intensification of oceanic circulation a rise in atmospheric po2 concentrations a sea level drop depressed primary productivity and low sedimentation rates this study calls for further high resolution sedimentological and geochemical investigations on the paleotropics outside south china in order to elucidate the icehouse greenhouse transition at the global scale

pattern and forcing of northern hemisphere glacier variations during the last millennium time series depicting mountain glacier fluctuations in the alps display generally similar patterns over the last two centuries as do chronologies of glacier variations for the same interval from elsewhere in the northern hemisphere episodes of glacier advance consistently are associated with intervals of high average volcanic aerosol production as inferred from acidity variations in a greenland ice core advances occur whenever acidity levels rise sharply from background values to reach concentrations 1 2 equiv h kg above background a phase lag of about 10 15 yr equivalent to reported response lags of alpine glacier termini separates the beginning of acidity increases from the beginning of subsequent ice advances a similar relationship but based on limited and less reliable historical data and on lichenometric ages is found for the preceding 2 centuries calibrated radiocarbon dates related to advances of non calving and non surging glaciers during the earlier part of the little ice age display a comparable consistent pattern an interval of reduced acidity values between about 1090 and 1230 a d correlates with a time of inferred glacier contraction during the medieval optimum the observed close relation between noothern hemisphere glacier fluctuations and variations in greenland ice core acidity suggests that sulfur rich aerosols generated by volcanic eruptions are a primary forcing mechanism of glacier fluctuations and therefore of climate on a decadal scale the amount of surface cooling attributable to individual large eruptions or to episodes of eruptions is simlar to the probable average temperature reduction during culminations of little ice age alacier advances ca 0 5 1 2 c as inferred from depression of equilibrium line altitudes

modelling the evolution of vadret da morteratsch switzerland since the little ice age and into the future we use a 3 d higher order glacier flow model for vadret da morteratsch engadin switzerland to simulate its strong retreat since the end of the little ice age lia and to project its future disintegration under a warming climate the flow model coupled to a 2 d energy balance model is initialized with the known maximum glacier extent during the lia and subsequently forced with mean monthly precipitation and temperature records to correctly reproduce the observed retreat of the glacier front for the period 1864 2010 additional mass balance perturbations are required to account for uncertainties in the initial state the mass balance model and climate variations not captured by the ambient meteorological records changes in glacier volume and area are in good agreement with additional information from historical topographic maps under constant 2001 10 climate conditions a strong retreat and mass loss continue and vadret da morteratsch disconnects from its main tributary vadret pers before 2020 the future glacier evolution is analysed in detail to understand the timing and rate of retreat and to assess the role of ice dynamics assuming a linearly increasing warming of 3 c by 2100 only isolated and largely stagnant ice patches remain at high elevation

the evolution of brittle and ductile structures at the surface of a partly debris covered rapidly thinning and slowly moving glacier in 1998 2012 pasterze glacier austria

meltwater runoff in a changing climate 1951 2099 at chhota shigri glacier western himalaya northern india meltwater runoff in the catchment area containing chhota shigri glacier western himalaya is simulated for the period 1951 2099 the applied mass balance model is forced by downscaled products from four regional climate models with different horizontal resolution for the future climate scenarios we use high resolution time series of 5 km grid spacing generated using the newly developed intermediate complexity atmospheric research model the meteorological input is downscaled to 300 m horizontal resolution the use of an ice flow model provides annually updated glacier area for the mass balance calculations the mass balance model calculates daily snow accumulation melt runoff as well as the individual runoff components glacial melt snowmelt and rain the resulting glacier area decreases by 35 representative concentration pathway rcp 4 5 scenario to 70 rcp 8 5 scenario by 2099 relative to 2000 the average annual mass balance over the whole model period 1951 2099 was 0 4 0 3 m w e a 1 average annual runoff does not differ substantially between the two climate scenarios however for the years after 2040 our results show a shift towards earlier snowmelt onset that increases runoff in may and june and reduced glacier melt that decreases runoff in august and september this shift is much stronger pronounced in the rcp 8 5 scenario

evidence for palaeo wildfire in the late permian palaeotropics charcoal from the motuca formation in the parnaiba basin brazil abstract the permian deglaciation of gondwana caused a global icehouse greenhouse transition leading to increased aridity over large parts of this continent during the lopingian contributing to the overall scarcity of plant bearing localities despite a continuous increase of reports of fossil charcoal as direct evidence for palaeo wildfires from late palaeozoic deposits such records from low latitude and arid to semi arid areas are still rare in order to contribute to the discussion about palaeoenvironmental conditions that dominated low latitudinal portions of the globe during that period and especially the occurrence of wildfires the present contribution reports on charcoal recovered from sandstones from the andradina outcrop late permian lopingian motuca formation in the parnaiba basin northern brazil this locality is part of the northern tocantins petrified forest which is classified as one of the most important permian assemblages of permineralized plant remains from warm temperate palaeobiomes of the southern hemisphere the results presented here provide the first evidence for the occurrence of palaeo wildfires in the western part of the gondwanan palaeo tropics during the lopingian

calendar dated glacier variations in the western european alps during the neoglacial the mer de glace record mont blanc massif holocene glacier records from the western european alps are still sparse although a number of sites are well suited to constraining pre and early little ice age lia glacier advances the present study provides the first dendrochronologically based and calendar dated neoglacial glacier chronology for the mont blanc massif french alps it is based on the analysis of over 240 glacially buried pinus cembra subfossil logs and wood remains found either embedded in till or as detrital material in the mer de glace right lateral moraine only a few of the samples were found to be formally in situ but we show that some logs were virtually in situ not rooted but showing little or no evidence of reworking and could be used to accurately reconstruct past glacier margin behavior in space and time uncertainties regarding the other samples may relate to original growth location and or to outer wood decay the resulting dates followed by a were therefore considered maximum limiting ages for glacier advances the main burial events interpreted as glacier advances occurred between ca 1655 and 1544 bc between ca 1230 and 1105 bc between ca 1013 and 962 937 bc at ca 802 777 bc after 608 bc between 312 and 337 ad between ca 485 ad and 606 ad between 1120 and 1178 ad between ca 1248 and 1278 1296 ad and after 1352 ad these advances predate the late lia maxima known from historical sources the magnitude of the advances gradually increased to culminate in three near neoglacial maxima during the 7th 12th and 13th centuries ad followed by a first lia neoglacial maximum in the second half of the 14th century ad the pattern of neoglacial events described here is coherent with central and eastern alpine glacier chronologies this indicates marked synchronicity of late holocene glacier variability and forcing at a regional scale although occasional differences could be detected between western and eastern records the mer de glace record also confirms the link between the timing of sediment erosion in a high elevation glaciated alpine catchment and subsequent deposition in the sub alpine lake bourget

contribution of glacier melt to sea level rise since ad 1865 a regionally differentiated calculation the contribution of glacier melt including the greenland ice sheet to sea level change since ad 1865 is estimated on the basis of modelled sensitivity of glacier mass balance to climate change and historical temperature data calculations are done in a regionally differentiated manner to overcome the inhomogeneity of the global distribution of glaciers a distinction is made between changes in summer temperature and in temperature over the rest of the year our best estimate of the ice melt in the period 1865 1990 in terms of sea level change equivalent is 5 7 cm 2 7 cm for glaciers and 3 0 cm for the greenland ice sheet additional calculations show that simpler methods like using annual or even global mean temperature anomaly give estimates that differ by up to 55 consequently a regionally differentiating approach is advised for making projections of glacier melt with gcm output

extending the database of permian palaeo wildfire on gondwana charcoal remains from the rio do rasto formation parana basin middle permian rio grande do sul state brazil abstract macroscopic charcoal has been recovered from a bonebed from the barro alto outcrop middle permian guadalupian rio do rasto formation in the southernmost part of the parana basin brazil during this time a global biotic crisis was taking place and changes in the palaeofloristic composition can be observed records of palaeowildfires from the guadalupian period are scarce on a global scale in the parana basin low plant diversity compared to the entirety of gondwana persists and just a few plant bearing localities have so far been described from the northern part of the basin in the studied locality macroscopic charcoal could be detected in an outcropping bonebed and the occurrence of palaeo wildfires was confirmed besides representing the first palaeobotanical data for the guadalupian of the southern part of the parana basin the charcoal remains analyzed here are also a significant record of the local environmental conditions during the increase in aridity observed during the guadalupian and lopingian in gondwana this contributes to the understanding of regional changes that took place during this interval

a flowline model for nigardsbreen norway projection of future glacier length based on dynamic calibration with the historic record historic glacier length variations are used to constrain a computer model for nigardsbreen norway a mass balance history is derived that when imposed on the flow model gives an almost perfect match between observed and simulated glacier length since ad 1748 being calibrated with past changes the model predicts an 800 in advance of the glacier snout if mass balance conditions remain as they were for the period 1962 93 several greenhouse warming scenarios are imposed to project the glacier s behaviour into the next century for a uniform heating rate of 0 02 k a nigardsbreen would advance slightly until ad 2020 but then a very rapid retreat would start in ad 2100 glacier volume would be only 10 of the 1950 volume

depositional setting and structural evolution of the archean perseverance volcanogenic massive sulfide deposit matagami mining district quebec canada the perseverance volcanogenic massive sulfide deposit 5 1 mt at 15 8 zn 1 24 cu 29 4 g t ag 0 4 g t au matagami district abitibi greenstone belt consists of four pipelike orebodies discordant to local bedding in a shallow dipping portion of the south flank volcanic succession most of the ore is hosted by rhyolitic lavas of the watson unit 2725 9 0 8 ma and is overlain by a thinly laminated tuffaceous unit known as the key tuffite as well as by rhyodacitic lavas of the dumagami unit 2725 4 0 7 ma the presence of sulfide zones predominantly hosted in the footwall rhyolite relicts of key tuffite within the ore and intricate sulfide replacement of the laminated tuff are all features consistent with the formation of most of the deposit via subseafloor replacement the permeability of steep synvolcanic structures likely controlled the migration of metal bearing fluids and simultaneously allowed the downward infiltration of seawater causing mixing cooling and sulfide deposition in the subseafloor environment stratigraphic relationships suggest that massive sulfide formation was active at perseverance while tuffaceous sedimentation was ongoing on the seafloor progressive growth of the massive sulfides along subvertical structures was accompanied by the development of pipelike sericite chlorite talc alteration halos both the hanging wall and the footwall units are characterized by significant mgo mass gains k 2 o na 2 o mass losses and high alteration index values e g chlorite carbonate pyrite index alteration index however these geochemical changes are less intense and widespread in the hanging wall than in the footwall the record of a decreasing alteration above the orebodies was likely caused by the emplacement of the rhyodacite while massive sulfide deposition and hydrothermal activity were still ongoing primary relationships between mineralization and the host lithofacies were overprinted by intense deformation during the main event of compression induced by regional north south shortening deformation is controlled by contrasting rheologies within the sulfide assemblage and between the orebodies and their host rocks structural modifications include the transposition of sulfide ores subparallel to the main foliation the formation of piercement veins at the interface with the host rocks and the generation of a series of secondary textures within the orebodies including a vertical mineralogical banding the distribution of cu in the deposit is interpreted to be affected by the mechanical remobilization of chalcopyrite during deformation whereas the zonation of zn is likely primary hydrothermal alteration halos adjacent to the orebodies have accommodated significant strain as indicated by the presence of tight folds in the key tuffite unit and a marked schistosity strain localization in the vicinity of the deposit highlights the relative ductility of the ore assemblage with respect to the host volcanic succession and resulted in a spatial association between hydrothermal alteration and deformation despite the lack of a genetic relationship

numerical modelling of historical front variations and dynamic response of sofiyskiy glacier altai mountains russia the recent fluctuation of the central asian climate and its effect on the region s glaciers is poorly known largely because of a lack of knowledge of the dynamic behaviour of so called summer accumulation type glaciers in this study a one dimen sional numericalglaciermodelisusedtosimulatethedynamicresponseof sofiyskiyglacier altai mountains russia to climate forcing a successful simulation of the observed histor ical front variations was accomplished by dynamic calibration this resulted in a recon struction of the recent mass balance history of the glacier showing a distinct decline in surface massbalance in the second half of the19th century a slightly higher massbalance at the beginning of the 20th century followed by a steady decline towards present condi tions the future response of sofiyskiy glacier was projected for six 21st century climate scenarios undera no change scenario the glacier will retreat 42kmby 2100 if airtem perature gradually risesby 45 c during this century the glacier will vanish around 2100 basic response characteristics of sofiyskiy glacier were determined these indicate rather low mass balance sensitivity to temperature change but a strong front reaction due to geo metric conditions

tectonic control on fluvial styles the balfour formation of the karoo basin south africa abstract the balfour formation represents a fully fluvial succession of late late permian earliest triassic age which accumulated in the foredeep of the karoo basin during the overfilled phase of the foreland system the lack of a coeval marine environment within the limits of the preserved karoo basin provides an opportunity to study the stratigraphic cyclicity developed during a time when accommodation was solely controlled by tectonics the balfour stratigraphy is composed of a succession of six third order fluvial depositional sequences separated by subaerial unconformities they formed in isolation from eustatic influences with a timing controlled by orogenic cycles of loading and unloading sediment accumulation took place during stages of flexural subsidence whereas the bounding surfaces are related to stages of isostatic uplift the vertical profile of all sequences displays an overall fining upward trend related to the gradual decrease in topographic slope during orogenic loading at the same time an upward change in fluvial styles can be observed within each sequence from initial higher to final lower energy systems the actual fluvial styles in each location depend on paleoslope gradients and the position of the stratigraphic section relative to the orogenic front proximal sequences show transitions from braided to meandering systems whereas more distal sequences show changes from sand bed to fine grained meandering systems the average duration of the balfour stratigraphic cycles was 0 66 my i e six cycles during 4 my no climatic fluctuations are recorded during this time with the long term climatic background represented by temperate to humid conditions

late quaternary glacier sensitivity to temperature and precipitation distribution in the southern alps of new zealand glaciers respond to climate variations and leave geomorphic evidence that represents an important terrestrial paleoclimate record however the accuracy of paleoclimate reconstructions from glacial geology is limited by the challenge of representing mountain meteorology in numerical models precipitation is usually treated in a simple manner and yet represents difficult to characterize variables such as amount distribution and phase furthermore precipitation distributions during a glacial probably differed from present day interglacial patterns we applied two models to investigate glacier sensitivity to temperature and precipitation in the eastern southern alps of new zealand a 2 d model was used to quantify variations in the length of the reconstructed glaciers resulting from plausible precipitation distributions compared to variations in length resulting from change in mean annual air temperature and precipitation amount a 1 d model was used to quantify variations in length resulting from interannual climate variability assuming that present day interglacial values represent precipitation distributions during the last glacial a range of plausible present day precipitation distributions resulted in uncertainty in the last glacial maximum length of the pukaki glacier of 17 1 km 24 and the rakaia glacier of 9 3 km 25 corresponding to a 0 5 c difference in temperature smaller changes in glacier length resulted from a 50 decrease in precipitation amount from present day values 14 and 18 and from a 50 increase in precipitation amount 5 and 9 our results demonstrate that precipitation distribution can produce considerable variation in simulated glacier extents and that reconstructions of paleoglaciers should include this uncertainty

hintereisferner austria mass balance reconstruction and numerical modelling of the historical length variations in this study an attempt is made to simulate the historical length variations of hintereisferner austria key elements in the model are 1 reconstruction of the local climate vent 2 multiple linear regression analysis between measured climate and mass balance variations 3 reconstruction of the mass balance with 1 and 2 4 a one dimensional numerical ice flow model forced by the mass balance history

marine flooding surfaces recorded in permian black shales and coal deposits of the main karoo basin south africa implications for basin dynamics and cross basin correlation abstract the marine origin of black shales in the context of the permian postglacial development of the karoo basin south africa is subject of an ongoing controversial discussion here we present and discuss palynological and sedimentological data providing evidence of a transgressive event during the early guadalupian palynofacies assemblages of the black shales of the southern basin include marine phytoplankton that exhibit peak abundance within the whitehill shales and which also occur within siltstones and glauconitic sandstones on top of the no 5 coal seam of the north eastern basin palynostratigraphic control makes this marine signal a powerful tool for cross basin correlation moreover palynofacies analysis demonstrates a facies transition from terrestrial lacustrine and fluvio deltaic in the northeast to deep marine in the south western parts of the basin

terminus response of lewis glacier mount kenya kenya to sinusoidal net balance forcing on a calcule la reponse de la langue terminale du lewis glacier a une fluctuation sinusoidale du bilan de masse le profil des bilans en fonction de l altitude est transcrit separement suivant des axes orthogonaux bilan altitude on a couvert des amplitudes de bilans de 0 1 a 0 5 m a 1 de glace et d altitudes de 10 a 50 m respectivement sur des periodes allant de 20 a 1000 ans la prise en compte de la reponse du lewis glacier en comparaison avec des resultats analogues pour d autres glaciers alpins permet de caracteriser les traits generaux de la reponse des langues

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

on thermal expansion over the last hundred years estimates of sea level rise during the period 1856 1991 due to thermal expansion are presented the estimates are based on an ocean model that consists of three zonally averaged ocean basins representing the atlantic pacific and indian oceans these basins are connected by a circumpolar basin that represents the southern ocean the ocean circulation in the model was prescribed surface ocean forcing was calculated from observed sea surface temperatures global mean forcing and regionally varying forcing were distinguished different parameterizations of ocean heat mixing were incorporated according to the model presented global mean sea level rise caused by thermal expansion over the last hundred years ranged from 2 2 to 5 1 cm a best estimate being 3 5 cm 34 refs 5 figs

deriving historical equilibrium line altitudes from a glacier length record by linear inverse modelling glaciers have fluctuated in historic times and the length fluctuations of many glaciers are known from these glacier length records a climate reconstruction described in terms of a reconstruction of the equilibrium line altitude ela or the mass balance can be extracted in order to derive a climate signal from numerous glacier length records a model is needed that takes into account the main characteristics of a glacier but uses little information about the glacier itself therefore a simple analytical model was developed based on the assumption that the change in glacier length can be described by a linear response equation historical length observations the climate sensitivity and the response time of a glacier were needed to calculate historical equilibrium line altitudes both climate sensitivity and length response time were calculated from a perturbation analysis on the continuity equation the model was tested on 17 european glacier length records the results revealed that the ela of most glaciers increased on average 54 m between ad 1920 and 1950 the results of the analytical model were compared to mass balance reconstructions calculated with a numerical flowline model and derived from historical temperature and precipitation records the findings lead us to believe that the analytical model could be very useful to gain information about the historical mass balance rates and elas

consideration of the errors inherent in mapping historical glacier positions in austria from the ground and space 1893 2001 the historical record of in situ measurements of the terminus positions of the pasterze and kleines fleiskees glaciers in the eastern alps of austria is used to assess uncertainties in the measurement of decadal scale changes using satellite data topographic maps beginning in 1893 and satellite data from 1976 to 2001 were studied in concert with ground measurements to measure glacier changes ground measurements show that the tongue of the pasterze glacier receded f1150 m from 1893 to 2001 while satellite derived measurements using august 2001 landsat enhanced thematic mapper plus etm data registered to an 1893 topographic map show a recession of 1300 1800 m with an unknown error the measurement accuracy depends on the registration technique and the pixel resolution of the sensor when two satellite images are used when using topographic maps an additional source of error is the accuracy of the glacier position shown on the map between 1976 and 2001 landsat derived measurements show a recession of the terminus of the pasterze glacier of 479f136 m at an average rate of 19 1 m a 1 while measurements from the ground showed a recession of 428 m at an average rate of 17 1 ma 1 four meter resolution ikonos satellite images from 2000 and 2001 reveal a shrinkage of 22 096f46 m 2 in the pasterze tongue the nearby kleines fleiskees glacier lost 30 of its area between 1984 and 2001 and the area of exposed ice increased by 0 44f0 0023 km 2 according to landsat satellite measurements as more recent satellite images are utilized especially data that are geocoded the uncertainty associated with measuring glacier changes has decreased it is not possible to assess the uncertainty when an old topographic map and a satellite image are coregistered

petrology and palynology of select coal samples from the permian waterberg coalfield south africa abstract the petrology and palynology of coals from the permian aged waterberg coalfield situated in the limpopo province of south africa are considered the waterberg coalfield contains a significant portion of the country s coal reserves but is still comparatively underexplored detailed maceral analyses combined maceral microlithotype analyses mean random and maximum vitrinite reflectance analyses etching and palynology studies were undertaken on coals from four productive horizons there is a general upward trend in vitrinite content through the sequence 15 59 vol mineral matter free dominated by collotelinite along with a slight decrease in coal rank the lower vryheid formation coal has a comparatively low mineral matter and high inertinite content dominated by inertodetrinite the upper grootegeluk formation samples contain above 35 vol mineral matter and liptinite contents ranging from 14 to 21 vol the use of blue light fluorescence in conjunction with incident light single scan method revealed that liptinite is intimately associated with inertodetrinite and mineral matter specifically clays and occasionally pyrite it is evident that the liptinite maceral content has previously been under reported in the waterberg coals the palynofloras correlate with the well studied witbank coalfield the petrography along with the palynology essentially confirm the palaeoenvironment of the karoo basin as progressing from a cooler more oxidising environment to a wetter seasonal environment

responses of various sized alpine glaciers and runoff to climatic change this paper presents a glacier ice flow model that simulates changes to alpine glaciers of various sizes and their runoff response to climate change in the yili river basin in the tien shall mountains northwestern china it is suggested that the sensitivity of glaciers to climatic change is determined by glacier size the change in glacial runoff does not keep pace with climactic change as climate warms and glaciers retreat the glacier runoff tends to increase and then decrease the runoff peak and its timing depend not only on glacier size but also on the rate of air temperature rise

numerical modelling of the historic front variation and the future behaviour of the pasterze glacier austria an ice flow model is used to simulate the front variations of the pasterze glacier austria the model deals explicitly with the ice flux from sub streams and tributaries to the main ice stream the dynamic calibration method adopted successfully calibrates the ice flow model under a non steady state condition despite the complexity of the glacier geometry the ice dynamics of the pasterze are adequately simulated results of the sensitivity experiments suggest that the pasterze glacier has been in a non steady state most of the time and has a response time of 34 50 years projections of the behaviour of the pasterze in the next 100 years are made under various climate scenarios results suggest that the pasterze will undergo a substantial retreat if there is future warming the glacier is likely to retreat 2 5 km by the year 2100 the ice volume could be reduced by 24 63 by the end of the 21st century

global and hemispheric temperature reconstruction from glacier length fluctuations temperature reconstructions for recent centuries provide a historical context for the warming over the twentieth century we reconstruct annual averaged surface temperatures of the past 400 years on hemispherical and global scale from glacier length fluctuations we use the glacier length records of 308 glaciers the reconstruction is a temperature proxy with decadal resolution that is completely independent of other temperature records temperatures are derived from glacier length changes using a linear response equation and an analytical glacier model that is calibrated on numerical model results the global and hemispherical temperatures reconstructed from glacier length fluctuations are in good agreement with the instrumental record of the last century furthermore our results agree with existing multi proxy reconstructions of temperature in the pre instrumental period the temperature record obtained from glacier fluctuations confirms the pronounced warming of the twentieth century giving a global cumulative warming of 0 94 0 31 k over the period 1830 2000 and a cumulative warming of 0 84 0 35 k over the period 1600 2000

south africa s coalfields a 2014 perspective abstract for well over a century and a half coal has played a vital role in south africa s economy and currently bituminous coal is the primary energy source for domestic electricity generation as well as being the feedstock for the production of a substantial percentage of the country s liquid fuels it furthermore provides a considerable source of foreign revenue from exports based on geographic considerations and variations in the sedimentation origin formation distribution and quality of the coals 19 coalfields are generally recognised in south africa this paper provides an updated review of their exploration and exploitation histories general geology coal seam nomenclature and coal qualities within the various coalfields autocyclic variability is the norm rather than the exception whereas allocyclic variability is much less so and allows for the correlation of genetically related sequences during the mid jurassic break up of gondwana most of the coal bearing successions were intruded by dolerite these intrusions are important as they may cause devolatilisation and burning of the coal create structural disturbances and related seam correlation problems and difficulties in mining operations whilst many of the coalfields have been extensively explored and exploited those in the north of the country have until recently received much less attention four coalfields occur partly or wholly within the limpopo province of south africa and these may contain as much as 70 of south africa s remaining coal resources these coalfields in particular have been the focus of recent exploration due to the presence of large coking and thermal coal resources as well as for their coal bed methane potential and these resources need to be unlocked with regards to creating maximum benefit and minimal environmental degradation south africa s coals have also been recently addressed as palaeoclimate archives recording gondwana s postglacial climate amelioration by major changes in land plant communities and proving high resolution palyno stratigraphy as a crucial tool to decipher climate change during the permo carboniferous this aspect of the coals of south africa is also reviewed

climate reconstruction since the little ice age by modelling koryto glacier kamchatka peninsula russia based on the field data at koryto glacier kamchatka peninsula russia we constructed a one dimensional numerical glacier model which fits the behaviour of the glacier the analysis of meteorological data from the nearby station suggests that the recent rapid retreat of the glacier since the mid 20th century is likely to be due to a decrease in winter precipitation using the geographical data of the glacier terminus variations from 1711 to 1930 we reconstructed the fluctuation in the equilibrium line altitude by means of the glacier model with summer temperatures inferred from tree ring data the model suggests that the winter precipitation from the mid 19th to the early 20th century was about 10 less than that at present this trend is close to consistent with ice core results from the nearby ice cap in the central kamchatka peninsula

the 1982 83 surge and antecedent quiescent phase of variegated glacier revising the original dataset for application in flow line models