facies architecture and depositional dynamics of the upper permian rangal coal measures bowen basin australia the upper permian rangal coal measures in the northern bowen basin australia accumulated during rapid basinal aggradation in a retroarc foreland basin setting they reflect peatland deposition towards the close of a long lived climatic regime that came to an abrupt termination at the permian triassic boundary which is well developed in the newlands mine highwall and adjoining borefield six lithofacies are represented in the newlands district 1 erosionally based vertically stacked ribbon and sheet like sandstone bodies up to 30 m thick and 1000 m wide 2 heterolithic lobes and wedges 3 interbedded siltstone and sandstone sheets 4 interlaminated claystone and coal stringers 5 laterally extensive bituminous coal sheets and 6 laterally extensive laminated carbonaceous siltstone sheets this facies assemblage is interpreted to correspond to six alluvial cold climate depositional environments 1 trunk river channels and crevasse feeder channels 2 levee bank proximal crevasse splay 3 distal splay overbank 4 marsh 5 peat mire and 6 floodbasin lake respectively the sequence architecture at newlands reveals that a prolonged period of peat deposition was progressively terminated by northward stepping lobes of fluvial sediment in the south and by lacustrine drowning in the north exceptionally well developed composite elongate crevasse splay microdeltas up to 26 m thick and 3000 m long indicate that crevassing was responsible for the localized emplacement of thick sediment packages on the proximal floodplain in the absence of active siliciclastic sedimentation peat mire environments expanded from the distal floodplain extending across abandoned depositional lobes the geometry of these deposits reflects in large part accommodation space developed by the compaction of the peat precursor of the thick and laterally extensive upper newlands seam sequential compaction of peat by clastic overburden controlled the nucleation and location of succeeding clastic packages the behavior of the peat under compactional load largely controlled the lateral facies mosaic and stacking pattern of depositional units on a district scale

reconciling heterogeneity in crystal zoning data an application of shared characteristic diagrams at chaos crags lassen volcanic center california isotope trace element and textural crystal zoning patterns record heterogeneity in magmatic systems not resolved by whole rock analyses these zoning data are used to infer crystal residence times magma mixing and other magmatic processes in many magmatic systems we present the shared characteristic diagram scd as an organizational framework for crystal zoning data that compares information from different phases and chemical tracers in a common framework an example from chaos crags in the cascade arc produces three main results 1 anorthite zoning profiles in plagioclase have fewer shared characteristics in mafic inclusions than in the host rhyodacite 2 single crystal 87sr 86sr data from previous studies tepley et al 1999 are consistent with more shared history between crystals than in anorthite profiles this difference reflects a more homogeneous distribution of 87sr 86sr than the intensive parameters controlling plagioclase composition 3 the chaos crags system exhibits a layer of heterogeneity in crystal populations that is not represented in whole rock analyses that indicate only simple binary mixing the inconsistency between 87sr 86sr and anorthite zoning data highlights decoupling between compositionally controlled and temperature water controlled zoning in plagioclase from chaos crags

control of relative sea level and climate on coal character in the westphalian c atokan four corners formation central appalachian basin u s a abstract peat successions preserved as coal seams preserve high resolution records of ancient terrestrial water table base level fluctuations that are driven by changes in relative sea level and or paleoclimatic change the aim of this study is to establish the roles of relative sea level and climate in controlling water table fluctuations within coal seams from the fluviodeltaic westphalian c bolsovian atokan four corners formation of the central appalachian basin usa comparison of the characteristics of 10 coals in the four corners formation with accommodation trends identified from analysis of intra coal clastic strata indicates that their thickness and vitrinite inertinite ratio correlate readily with the accommodation setting of the depositional sequence in which they occur coals that accumulated in relatively high accommodation fourth order sequences are high in vitrinite thin and overlain by or intercalated with marine and lacustrine sediments the coals have simple internal organization suggesting that they span parts of single high resolution accommodation cycles coals that accumulated in lower accommodation fourth order sequences are high in inertinite thick and overlain by or intercalated with terrestrial sediments the coals have composite internal organizations typified by multiple high resolution accommodation cycles and characteristic abrupt discontinuities of coal facies representing periods of depositional hiatus the correlations between the composition and thickness of the coals and the magnitude of associated marine transgression imply that relative sea level change was the principal control governing bulk accommodation in these mires landward of the paleoshoreline high frequency accommodation cycles within the coals reflect water table fluctuations in the original mires and were driven by high frequency sea level and or climate change the results of this study provide considerable insight into the manner in which coal composition and stratigraphy at a single locality vary over time in response to changing accommodation and provide a means to predict coal seam quality in an established sequence stratigraphic framework

accuracy of timescales retrieved from diffusion modeling in olivine a 3d perspective diffusion modeling in olivine is a useful tool to resolve the timescales of various magmatic processes practical olivine geospeedometry applications employ 1d chemical transects across sections that are randomly sampled from a given 3d crystal population but the accuracy and precision with which timescales can be retrieved from this procedure are not well constrained here we use numerical 3d diffusion models of fe mg to evaluate and quantify the uncertainties associated with their 1d counterparts the 3d diffusion models were built using both simple and realistic olivine morphologies and incorporate diffusion anisotropy as well as different zoning styles the 3d model crystals were sectioned along ideal or random planes which were used to perform 1d models and timescale comparisons results show that the timescales retrieved from 1d profiles are highly inaccurate and can vary by factors of 0 1 25 if diffusion anisotropy is not taken into account even when anisotropy is corrected for timescales can still vary between 0 2 10 times the true 3d diffusion time due to crystal shape and sectioning effects simple grain selection procedures are described to reduce the misfit between calculated and actual diffusion times and achieve an accuracy and precision of 5 and 15 25 relative respectively provided that the grains are carefully selected about 20 concentration profiles and associated 1d models suffice to achieve this accuracy

the significance of hiatal surfaces in coal seams abstract a widespread misconception is that coals correspond to single palaeo peat bodies which represent continuous and time invariant records of peat accumulation evidence for the occurrence of intra seam hiatal surfaces within datasets from bituminous coals lignites and modern peats suggests that existing depositional models for peat and coal require modification recognition that coals may represent a succession of stacked mires separated by hiatal surfaces has implications for palaeoenvironmental and sequence stratigraphic studies that assume a continuous record of peat accumulation as well as for the prediction of whole seam composition and thickness trends

organic geochemical investigations of brown coal lithotypes a contribution to facies analysis of seam banding in the helmstedt deposit abstract samples of light medium light and dark lithotypes from the eocene helmstedt brown coal deposit were examined by organic geochemical methods soxhlet extraction liquid and gas chromatography gc ms the study is part of a facies analysis of banded brown coals there are significant differences between the lithotypes concerning the extractable organic matter yields the composition of the extracts and the composition of the alkane fractions on average the light brown coals produce three times as much extractable organic matter as the dark ones asphaltenes and resins are the main components of the extracts of the light lithotypes hydrocarbons and n s o compounds of lower molecular weight are less abundant than in the dark lithotypes the alkane fraction of light lithotypes contains more n alkanes of high molecular weight and more saturated triterpenoids hopanes excluding homohopane but less unsaturated polycyclic compounds rearranged sterenes triterpenes and less homohopane the generally low concentrations of cyclic diterpanes norabietane norpimarane do not reveal any relationship to the three lithotypes based on these results there is no support for the conventional assumption that the light and dark brown coal lithotypes originated from different plant communities of the paleomoor the results rather suggest that the banding within the seam of the helmstedt brown coal deposit results from different biogeochemical degradation and transformation processes these processes are considered to be dependent on the environment of the paleomoor

sequence stratigraphic interpretation of peatland evolution in thick coal seams examples from yimin formation early cretaceous hailaer basin china abstract peat formed in mire settings sensitively records environmental fluctuations during deposition including changes in water table or base level and accommodation on this basis coal seams as geologically preserved peats can provide evidence of high resolution paleoclimatic fluctuations as well as paleobotanical evolution through periods of peat formation the no 2 and no 1 in ascending order thick coal seams from the early cretaceous yimin formation in the zhalainuoer coalfield hailaer basin ne china are investigated using sedimentological sequence stratigraphic and petrographic analyses to understand the evolution of their peat forming environments these single thick coal seams lacking siliciclasitic partings are well developed in the central area of the zhalainuoer coalfield petrographic analyses demonstrate that water table or base level fluctuations in single seams can be revealed by a number of significant surfaces formed by various events including paludification give up transgressive accommodation reversal flooding and exposure surfaces these surfaces can separate the single coal into a number of wetting up and drying up cycles the wetting up cycle is characterized by a gradual upward increasing trend in the huminite inertinite ratio and in the ash yields in contrast the rapid drying up cycle is characterized by an upward increasing trend in the inertinite dominated coal 46 on average that represents a phase of exposure and oxidation resulting from a falling water table this drying up cycle can be correlated with the scouring surface in landward parts of the basin and terrestrialization surface basinward the no 2 coal seam occurs in the transgressive systems tract and comprises three high frequency depositional sequences in which each coal cycle is characterized by a gradual wetting up cycle and ends with a rapid drying up cycle the no 1 coal seam occurs in the highstand system tract and consists of several high frequency depositional sequences in which each coal cycle is characterized by a gradual drying up cycle and ends with a rapid wetting up cycle these coals could also superpose to constitute the thick coal seam in which various sequence stratigraphic surfaces can be recognized including terrestrialization accommodation reversal and exposure surfaces stratigraphic relationships between coal and clastic components in the yimin formation enable us to demonstrate that thick coals span the formation of several coal cycles and high resolution boundaries allowing us to interpret the effects of accommodation on coal seam composition recognition that environmental changes can be recorded by thick coals has significance for studies that incorrectly suppose that peat or coal cycles can offer high resolution and time invariant records of paleoclimatic fluctuations and paleobotany evolution

the middle miocene yallourn coal seam the last coal in australia abstract the 100 m thick middle miocene yallourn brown coal seam was the last of the major latrobe valley group seams to form in the gippsland basin southeastern australia and the final major coal to form in australia coal deposition coincided with the middle miocene climatic optimum during this warm period of relatively high sea levels high water tables and relatively high subsidence rates a 565 km 2 area of alternating eutrophic and ombrogenous peat swamp developed at the western end of the latrobe valley to form the yallourn seam stratigraphic units of the seam contain a high sclerophyll plant component and abundant charcoal suggesting seasonal dry periods alternated with wet warm conditions characterised by abundant rushes and dense kauri forests iron content in parts of the yallourn seam is relatively high and a strong correlation exists between the iron distribution and the abundance of proteoid roots mainly proteaceae an indicator of seasonal dry periods the contemporaneous carbonates of the wuk wuk marl were deposited in a high productivity upwelling warmer water subtropical environment a new carbon isotope profile at 1 m intervals through the yallourn seam shows a poor relationship between 13 c isotopes and coal colour but some correlation with gymnosperm abundance the 13 c record also correlates well with long term secular changes in climate the presence of global carbon maxima cm2 cm4 and with the deep sea 13 c marine organic record thick coal seam development ended near the end of the middle miocene climatic optimum the termination of coal seam deposition in latrobe valley was primarily the result of tectonic compression uplift and development of adjacent highland relief and erosion at the end of the miocene

petrogenesis of the zagami meteorite inferences from synchrotron x ray sxrf microprobe and electron microprobe analyses of pyroxenes abstract the zagami meteorite is a shergottite a basalt rich in pigeonite augite and maskelynite glass shocked plagioclase it is one of the snc meteorites which are inferred to have formed on mars major and minor element abundances in pyroxene principally pigeonite from newly available unm samples were determined by electron microprobe abundances of trace elements ni cu zn and ga were obtained by synchrotron x ray sxrf microprobe many pigeonite grains have normally zoned rims and reversely zoned cores so that the most magnesian pigeonite forms rings or annuli in thin section view in three dimensions the most magnesian pigeonite may form tubes or hourglass shapes the cores commonly contain magmatic inclusions other pigeonites have irregular or multiple magnesian regions with magmatic inclusions among and between them abundances of ni and cr in the magnesian zones and cores are partially decoupled from abundances of other compatible mg and incompatible fe ti elements the textures chemical zoning and element decouplings in the pigeonites are consistent with igneous crystal growth at moderate cooling rates not isothermally or near equilibrium from element partitioning and mass balance the unm zagami is estimated to contain 20 5 or less cumulus pyroxene half augite and half pigeonite half the proportion suggested by equilibrium distribution of fe mg between pigeonite and melt this inconsistency may be resolved if all pigeonite melt element partitioning was affected by the rapid growth of the pigeonites the composition of the parental magma for the unm zagami calculated by mass balance on bulk and pyroxene compositions is similar to the 1170 c melt of the bmnh zagami not the 1140 c melt inferred as parental by other workers the inference that the pyroxene zoning patterns reflect only magmatic events is consistent with an igneous age of 180 m y for zagami

geological processes that control lateral and vertical variability in coal seam moisture contents latrobe valley gippsland basin australia abstract a study throughout the latrobe valley coal measures of coal moisture distribution using downhole bore data and 3d digital models of large bore data sets indicates lateral and vertical moisture variability is controlled by a number of factors these include burial type of overburden age of the seam marine influence coal lithotype and lateral compression on folds and monoclines the same rules appear to apply to the adjacent alberton coal measures in the south gippsland basin suggesting these factors may be widespread in other brown coal basins where moisture contents are still equilibrating through differential compaction in gippsland average moisture down seam decreases by 1 2 per seam and at a rate of approximately 1 every 20 m weight average moisture content for each seam decreases on average at a rate of 0 5 every 1 million years a stepwise decrease in moisture content between the 100 m thick major seams of 1 7 reflects large intervals of time are represented by the relatively thinner 1 10 m thick interseam sediments compression by monoclinal folding can decrease moisture contents up to 7 for any given depth moisture content appears higher on anticlines due to a lowered intensity of compression than in adjacent synclines it is considered likely that coals folded over anticlines are more fractured thereby containing greater amounts of free water use of the lower moisture coals and monoclinal coals may be preferable for future power station developments despite an increase in overburden coal ratios there would be significant savings in a lowered coal volume to calorific value and a consequent reduction in greenhouse gas emission

wavelet based correlation wbc of zoned crystal populations and magma mixing magma mixing is a common process and yet the rates kinematics and numbers of events are difficult to establish one expression of mixing is the major trace element and isotopic zoning in crystals which provides a sequential but non monotonic record of the creation and dissipation of volumes of distinct chemical potential we demonstrate a wavelet based correlation wbc technique that uses this zoning for the recognition of the minimum number of mixing or open system events and the criteria for identifying populations of crystals that have previously shared a mixing event when combined with field observations of the spatial distribution of crystal populations wbc provides a statistical link between the time varying thermodynamic and fluid dynamic history of the magmatic system wbc can also be used as a data mining utility to reveal open system events where outcrop is sparse an analysis of zoned plagioclase from the tuolumne intrusive suite provides a proof of principle for wbc 1 2002 elsevier science b v all rights reserved

the genesis of coal from the viewpoint of coal petrology abstract the genesis of the microscopic constituents of coal macerals and of maceral associations microlithotypes representing various coal facies is discussed in the light of recent advances that have been made in the study of coals and modern peats peat microscopy especially promoted the understanding of humification and biological gelification both of which are decisive for the genesis of huminites vitrinites in brown coals and hard coals respectively microbial activity during peatification has been documented by chemists microbiologists and petrologists and recently by electron microscopical observations in coals this activity leads to the incorporation of lipid substances into the humic matter and later influences the chemical physical and technological properties of vitrinites geochemical gelification transforms the huminites of brown coals into the vitrinites of bituminous coals and is probably caused by the onset of bitumen generation in coal in this process the hydrogel brown coal is transformed to the bitumogel bituminous coal coal as a source rock for oil has become an important research subject for coal petrologists and oil exploration the formation of more or less liquid bitumen and its later cracking to gaseous hydrocarbons leads to the coalification jumps of the macerals especially liptinites and vitrinites and to the generation of secondary macerals like exsudatinite bitumen and micrinite dead carbon bituminization in coal has been revealed by the use of fluorescence microscopy which also found the presence of new liptinite macerals bituminite fluorinite and exsudatinite and suggests a higher proportion of algal material in coals than was thought earlier the genesis of various types of inertinite macerals will probably become an increasingly important subject of research especially with regard to rank inertinites that seem to attain their high inertinitic reflectance initially during coalification besides the origin of macerals the origin of various coal facies in terms of maceral associations is considered in relation to the palaeogeographic depositional milieu the peat forming vegetation palaeoclimate water and nutrient supply acidity marine and calcareous influence and fire with examples from euramerican carboniferous coals gondwana coals and tertiary brown coals vegetation water and oxygen supply eh conditions are most important for the generation of coal facies vegetation has been reconstructed with the help of palaeobotany including palynology cuticular analysis and wood anatomy in brown coals and with the study of petrified permineralized peats preserved in coal balls the microscopical investigations of botanically recognizable plant remains isolated from coals or accompanying rocks has been especially informative however the results of palynological and cuticular analyses should be evaluated with caution considering the varying resistance of palynomorphs and cuticles and in the case of palynomorphs their possible extrapaludal origin microscopical studies of modern peats that were derived from different types of vegetation growing in different hydrological environments have been very helpful in interpreting coal facies especially in brown coals the much disputed origin of brown coal lithotypes is considered in detail for hard coals there seems to be agreement that coal layers rich in vitrites and liptinite poor clarite were deposited in wet forest swamps that microlayered liptinite rich clarites are sub aquatic humic muds and that inertinite rich durites represent oxidized peats the origin of liptinite rich durites is controversial either subaquatic muds or oxidized peats the latter perhaps from raised bogs a recent trend in the literature is the assumption that many if not all mineable coal seams have been deposited in raised bogs under ombrogenous oligotrophic conditions although raised bogs with a dense arborescent vegetation are known from borneo it seems not probable that most seams which were deposited in foredeeps or steadily sinking graben zones are of ombrogenous origin although a succession from relatively wet and eutrophic to relatively dry and oligotrophic conditions may be true for occasional seams but as in modern peats striking changes of coal facies are commonly caused by hydrological events e g inundations as a consequences of crevasses or of fires that burned the peat the origin of the inertinite rich gondwana coals is discussed in relation to their specific climatic conditions and a comparison with sub arctic peats is recommended coals influenced by marine and calcareous conditions are characterized by high contents of sulfur and pyrite as well as by hydrogen rich vitrinites with a relatively low reflectance and high fluorescence all due to a strong bacterial activity in peats of low acidity proposals for further research are made in the conclusions

marine flooding events and coal bed sequence architecture in southern west virginia abstract eight regional lower to middle pennsylvanian coal beds namurian b c to westphalian c in southern west virginia were examined beds were divided into their component sedimentary parts or benches by identifying bounding surfaces and associated siliciclastic partings within beds bounding surfaces represent the cessation of peat accumulation paleo peat mire morphology at the bench level was determined using shape analysis petrographic indices and coal chemistry data planar and raised paleo peat mire benches were identified all gas coal and some splint coal benches were derived from raised mires heterolithic coal and the remaining splint coal benches were derived from planar mires most bounding surfaces are thin composed of oxidized and degraded organic materials high in ash and sulfur content and contain clay minerals and silt sized quartz vitrinite reflectance is suppressed in the upper part of some benches the associated siliciclastic parting materials when thick show evidence of tidal influence and contain brackish water to marine trace fossil assemblages bounding surfaces and the associated sediments represent a sudden increase in water depth and the lateral continuity of these surfaces indicates regional to basinal extent bounding surfaces are the up paleoslope expression of rapid

the nature and evolution of lithotypes in the tertiary brown coals of the latrobe valley southeastern australia abstract lithotype banding identified on colour and texture of the coal occurs in all seams covering the period mid eocene to late miocene in the latrobe valley preliminary palaeobotanical studies on both pollen and plant macrofossil components of the youngest seams indicated strong relationships between lithotype vegetation and inferred depositional environment with the lithotype gradient from lightest to darkest coals corresponding with hydroseral stages from unvegetated open water through swamp forest to raised bog communities subsequent studies on the older seams failed to show such close correspondence between lithotype and vegetation the analysis of palynological and petrological data from all seams in this paper adds support to the original hypothesis of lithotype formation however it also demonstrates a gradual differentiation of lithotypes through the coal forming period this most likely involved the progressive development of vegetation communities adapted to the range of swamp environments with the peatforming environment of particular significance is the development of a community with a significant sclerophyll component within the predominant rainforest vegetation which colonised the raised bogs of the youngest seams the process may have been facilitated or accelerated by an increasingly variable climate and the increased importance of fire within the region

observations of plagioclase zoning using interference imaging abstract interference imaging techniques laser interference microscopy in transmitted light and nomarski differential interference contrast in reflected light have been used to study different types of zoning in magmatic plagioclase crystals samples studied come from a wide range of rock types and geological environments analysis of zoning profiles for individual unit zones shows that a saw tooth pattern in which an initially high an decreases as growth proceeds is the most common type of zoning configuration we recognize 2 major types of zoning type 1 small zones usually less than 10 microns thick with compositional amplitudes up to 10 an and type 2 zones up to50 microns thick with large compositional amplitudes of up to 35 an detailed analysis of zoning patterns shows that oscillatory zoning is not actually oscillatory in the sense of a sine wave it is discontinuous unit zones are characteristically bounded by discontinuities this common pattern is consistent with alternating periods of growth and periods of dissolution reaction and lack of growth or possibly very slow growth our observations firmly establish that dissolution and magmatic reaction involving both growth and dissolution are common during growth of the magmatic plagioclase which we have studied type 1 zonation appears consistent with perturbations of local conditions in a diffusion controlled boundary layer around the growing crystal type 2 zoning is probably due to large scale conditions faceted planar growth surfaces appear to be the rule in magmatic crystallization although in some instances rounded or irregular convolute zonation can occur the repetitive nature of many of the features we have observed is consistent with and suggestive of some form of self organization

new interpretations of the facies of the rhenish brown coal of west germany abstract new ideas concerning the understanding of the facies of the rhenish brown coal of west germany are discussed these new interpretations are based on a significantly larger number of samples and refined procedures for analysis within the field of paleobotany palynology coal petrology and organic geochemistry than were available to p w thomson and m teichmuller the light and dark bands in the coal are mainly the result of different degrees of plant decomposition the influence of the peat forming plant communities plays a subordinate role in the petrographical composition of these particular strata of the rhenish brown coal

orbital tuning and correlation of 1 7 m y of continuous carbon storage in an early miocene peatland peatland is an important terrestrial carbon reservoir that contains 25 of soil carbon and accounts for 25 38 of natural methane emissions most of this carbon is contained in postglacial boreal peat our understandingof the carbon cycle within this reservoir and its links to the atmosphere is therefore restricted to periods of 1 m y spectral analysis of varying lignite color reveals that 120 m of early miocene lignite from the gippsland basin australia contains a 1 7 m y record of orbitally paced climate oscillations dominated by the response to obliquity use of the regular orbital signal indicates that the average long term rate of peatland carbon accumulation recorded in the lignite is 27 5 g m 2 yr 1 this rate is constant over periods of 100 k y and is independent of shorter term 10 k y fluctuations in climate and hydrology matching the lignite record to the theoretical insolation curve indicates that the lignite formed between 22 5 and 20 8 ma contemporaneous long term changes in lignite color and the 1 3 c 1 2 c ratios of marine foraminifera may relate to changing peatland methane flux and thus point to a link between terrestrial and marine carbon dynamics

sequence stratigraphic analysis and the origins of tertiary brown coal lithotypes latrobe valley gippsland basin australia abstract the methods of sequence analysis have been applied to the onshore gippsland basin and in particular to the latrobe valley group coal measures which include up to five coal seams each exceeding 100 m in thickness the methods appear to provide new depositional concepts to the evolution of these seams and the development of coal lithotypes in the eastern half of the latrobe valley evidence for marine transgressions into the coal measures are recorded in most of the interseam sediment splits by the presence of contained foraminifera and dinoflagellates to the west inland these splits pinch out into continuous coal however they can be followed westwards as enhanced organic sulphur levels along sharply defined boundaries between light coal lithotypes below and dark coal lithotypes above the dark lithotype immediately overlying each of these boundaries contains the highest sulphur value and warmer climate pollen assemblages sluiter et al 1995 this volume colorimeter and lithotype logging strongly supports an upwards lightening cyclicity to coal colour at 12 20 m intervals through the approx 100 m thick seams with cycle boundaries defined at sharp planar to undulating surfaces the lightening upward lithotype cycles together with their unique boundary conditions i e enhanced organic sulphur levels warm climatic indicators and laterally equivalent marine clay splits are interpreted as parasequences and parasequence boundaries respectively each major coal seam can comprise up to five parasequences and is interpreted to represent deposition during an outbuilding high stand systems tract at one of several maximum periods of tertiary coastal onlap the top of each major seam shows evidence of truncation erosion on a regional scale and these surfaces are interpreted to represent the sequence boundaries the major seams are usually conformably underlain by marine clays and extensive aquifer sands being deposits of the late transgressive systems tracts the low stands and early parts of the transgressive systems tracts appear not to be represented in the latrobe valley due to its more basin margin location but are probably present down dip in the equivalent marine facies of the seaspray group stratigraphic correlation of the sequence boundaries identified in the coal measures to the adjacent internationally dated marine seaspray group provides a basis for chronostratigraphic correlation of the coal successions to the coastal onlap charts of haq et al exon mesozoic cenozoic chronostratigraphic chart version january 1988 and august 1989 from this dating it appears that each major seam is confined to high stands of third order eustatic cycles it therefore follows that the lithotype cycles parasequences that comprise each seam are related to fourth order eustatic cycles by analogy all the coal cycles may have developed under subtropical conditions as ombrogenous forested peat swamps in a similar manner to the holocene though tropical swamps of indonesia

unraveling the presence of multiple plagioclase populations and identification of representative two dimensional sections using a statistical and numerical approach many plagioclase phenocrysts from volcanic and plutonic rocks display quite complex chemical and textural zoning patterns understanding the zoning patterns and variety of crystal populations holds clues to the processes and timescales that lead to the formation of the igneous rocks however in addition to a true natural complexity of the crystal population the large variety of plagioclase types can be partly artifacts of the use of two dimensional 2d petrographic thin sections and random cuts of three dimensional 3d plagioclase crystals thus the identification of the true number of plagioclase populations and the decision of which are representative crystal sections to be used for detailed trace element and isotope analysis is not obvious and tends to be subjective here we approach this problem with a series of numerical simulations and statistical analyses of a variety of plagioclase crystals zoned in 3d we analyze the effect of increasing complexity of zoning based on 2d chemical maps e g backscattered electron images bse we first analyze the random sections of single crystals and then study the effect of mixing of different crystal populations in the samples by quantifying the similarity of the compositional histogram of about a hundred 2d plagioclase sections it is possible to identify the so called reference and ideal sections that are representative of the real 3d crystal populations these section types allow filtering out the random cut effects and explain more than 90 of the plagioclase compositional data of a given sample our method allows the identification of the main crystal populations and representative crystals that can then be used for a more robust interpretation of magmatic processes and timescales

the origin of bl zones in komatiite flows b1 zones of differentiated komatiite lava flows are thin layers less commonly texturally and geochemically differentiated than a few tens of centimetres composed predominantly of skeletal and show distinctive layering unique to rapidly cooled hopper olivine crystals with hollow cores and irregular morphologies ultramafic flows the typical layering of a komatiite pyke detailed textural and geochemical studies of two archaean komatiite et al 1973 arndt et al 1977 consists of two major flows from the reliance formation belingwe greenstone belt zones a lower olivine cumulate region b zone containing zimbabwe reveal that the b1 olivines show reverse size grading abundant polyhedral olivines and an upper a zone charand constant mg number compositions 91 1 91 6 1 5 acterized by elongate and highly skeletal spinifex olivines olivines of this composition would have been in equilibrium with at the boundary between the two zones a subdivision the estimated initial melt composition 20 wt mgo suggesting of the cumulate zone is often apparent this b1 zone is that the b1 crystals nucleated before or very soon after emplacement characterized by hopper olivine crystals which have of the flow mass balance calculations indicate that the b1 zones hollow cores and highly embayed edges giving the crysare regions of net olivine accumulation a model is presented for the tals a skeletal appearance these hopper crystals are formation of b1 zones which is applicable to all komatiite flows morphologically distinct from the polyhedral olivines in that crystallized as closed magmatic systems a convecting magma the lower b2 zone and the extremely elongate skeletal is erupted containing polyhedral phenocrysts and skeletal crystals spinifex olivines in the overlying a zone fig 1 subsequently grow during flowage on emplacement polyhedral the formation of the b1 zone and the origin of the phenocrysts settle rapidly to form the cumulate pile skeletal crystals hopper crystals are poorly understood and have been the with lower settling velocities become segregated from the polyhedral subject of much debate e g arndt 1986 turner et al phenocrysts during settling some are maintained in convection 1986 thomson 1989 the b1 layer varies greatly in achieving large elongate habits these crystals eventually settle thickness between flows 0 0 85 m and typically occupies horizontally onto the cumulate pile creating the reverse grading and 8 of the total flow thickness it is not present in all typical fabric of b1 zones komatiite flows the shape of the hopper crystals within the b1 zone varies from equant to elongate 12 1 aspect ratios with elongate crystals often showing a preferred orientation sub parallel to the flow top arndt 1986

using hydrogeochemistry to understand inter aquifer mixing in the on shore part of the gippsland basin southeast australia groundwater in the latrobe valley in the gippsland basin of southeast australia is important for domestic agricultural and industrial uses this sedimentary basin contains a number of aquifers that are used for water supply dewatered for open pit coal mining and which are potentially influenced by off shore oil and gas production major ion chemistry together with stable and sr isotope data imply that the main hydrogeochemical processes are evapotranspiration with minor silicate and carbonate weathering methanogenesis and so4 reduction in reduced groundwater associated with coal deposits have also occurred groundwater has estimated 14c ages of up to 36ka and is largely 3h free carbon 14 ages are irregularly distributed and poorly correlated with depth and distance from the basin margins the observations that the geochemistry of groundwater in aquifers with different mineralogies are similar and the distribution of 14c ages is irregular implies that the aquifers are hydraulically connected and horizontal as well as vertical inter aquifer mixing occurs the connection of shallow and deeper aquifers poses a risk for the groundwater resources in gippsland as contaminants can migrate across aquifers and dewatering of shallow units may impact deeper parts of the groundwater system

mid ocean ridge magma chamber processes constraints from olivine zonation in lavas from the east pacific rise at 9 30 n and 10 30 n 1 lavas from the northern east pacific rise with both robust 9 30 n and nonrobust 10 30 n ridge morphologies have compositionally diverse populations of plagioclase and or olivine due to magma mixing we interpret zoning in olivines to be primarily due to diffusion after mixing events which allows us to calculate the residence times of individual crystals in the magma for the four studied samples olivine populations exhibit exponential distributions of calculated diffusion times with short times exponentially more abundant than longer times we model this distribution as resulting from mixing in an open system axial magma chamber magma residence times in axial chambers at east pacific rise 9 30 n and 10 30 n for the four studied samples are of the order of months surprisingly we find that the differences in mineralogy and magma residence times between robust and nonrobust east pacific rise segments are not significant taken together our observations and measurements suggest that the seismically imaged melt lens of the axial magma chamber does not play a significant role in controlling the crystal content and characters of erupted lavas

magmatic crystal stratigraphy and constraints on magma chamber dynamics laser interference results on individual phenocrysts this work reports progress in current studies of zoning of magmatic crystals from basalts and andesites a simple law of normal growth is tested using zoning profiles of olivine and plagioclase crystals and is shown to be compatible with the zoning profiles of some olivines and parts of complexly zoned plagioclases using a convenient linearizing technique in which the ratio of compositional end members is plotted against volume we can identify those parts of the zoning profile which fit a simple normal growth law this technique permits easy identification of those parts of a complexly zoned crystal which require a more complex law of growth calculations used in this modeling are similar to those previously used for olivine pearce 1984c 1987 and are now extended to plagioclase it is concluded that it is both theoretically possible and practically feasible to make inferences about the liquid in the local system from which a crystal grew by examining the detailed zoning pattern of the crystal

a review of the traralgon formation in the gippsland basin a world class brown coal resource the traralgon formation contains by far the largest brown coal resources in the gippsland basin and is probably unequalled in the world for any single basin deposit of its type out of an indicated resource of 345 billion tonnes gt approximately 10 gt are currently listed as economically recoverable reserves low ash content ave 2 9 db but higher organic sulphur contents ave 1 72 db largely reflect the near coastal depositional environments under which much of the original extensive peat swamps accumulated the contained plant matter and coal types indicate a high latitude rainforest environment where rainfall and temperatures were higher than present and where lithotype cycling occurs the coals appear to have accumulated at specific high stand periods of coastal onlap towards the end of the middle and late eocene and eustatic sea level changes play an important role in development of the coal seams the timing for maximum coal accumulation takes place at the apogee of a greenhouse world shortly before the cooling trends into the early oligocene during this time over 100 gt of carbon was sequestered into these coal deposits

marine influence helps preserve the oil potential of coaly source rocks eocene mangahewa formation taranaki basin new zealand abstract many cretaceous cenozoic coaly source rocks in australasian and southeast asian basins were deposited in coastal plain environments yet the effect of early diagenetic marine influence on their oil potential is not well understood an integrated organic geochemical and petrographic study of humic coals from the eocene mangahewa formation taranaki basin new zealand was undertaken with coals predominantly from raised mire petrofacies with subordinate proportions from planar mires the total s content of 0 63 4 4 dry ash free indicated very slight to strong degrees of marine influence other than minor addition of inferred mangrove derived suberinite and associated liptodetrinite the degree of marine influence had no obvious effect on maceral or plant tissue abundance however hydrogen index hi values were up to ca 150 109 mg hc g toc higher and total c 6 oil potential up to ca 140 43 mg g toc higher among the more strongly marine influenced coals correlation of organic s with solvent extract parameters pristane phytane c 27 c 29 diasteranes steranes c 29 steranes hopanes c 35 c 35 c 34 homohopanes and oleanane index suggested that inundation of brackish water into the early diagenetic peat forming environment enhanced the bio resistance of higher plant and other lipids through sulfurization thereby helping to preserve more of the inherent h content and total oil potential of the original peat biomass conversely marine influence had only a minor effect on the capacity of mangahewa coals to generate paraffinic oil total n c 6 and non volatile n c 15 paraffinic oil potentials were instead controlled primarily by the abundance of leaf derived cutinite and associated liptodetrinite this in turn was dependent on the type of peat mire facies with planar mire facies having better potential for preservation of leaf litter than raised mire facies because of their generally higher groundwater level marine influence is nonetheless beneficial for paraffinic oil charge from coaly source rock sequences in that the associated higher his enhance the efficiency and quantum of paraffinic oil expulsion through increased saturation of the coal pore system

the analysis of zoning in magmatic crystals with emphasis on olivine many of the observed features of zoning in magmatic phenocrysts may be due to the orientation of the section rather than inherent properties of the crystals an ideal section for the studying of zoning in magmatic crystals has two characteristics it goes through the center of the crystal and is perpendicular to one or more crystal faces using a model zoned olivine crystal it is possible to construct accurate zoning profiles for different types of section centered symmetrical and skewed the probability of obtaining a random section which passes within x of the center of a crystal is shown to be p 0 0x while the probability that a random section will be within a degrees of perpendicular to a given plane is p sin a a systematic approach to the study of zoned crystals is outlined in particular it is suggested that composition be plotted against distance cubed in order to correct for the volume versus size problem a method of determining if a given section goes through or near the center of a zoned crystal is also presented the reasoning in this work applies to other types of magmatic crystals such as pyroxenes and plagioclase

facies relationships and cyclicity of high latitude late permian coal measures bowen basin australia the late permian moranbah coal measures are developed throughout the northern and central bowen basin eastern australia and are subject to large scale opencut coal mining activity they were deposited in a rapidly subsiding retroarc foreland basin during frequent base level changes contemporaneous compressive deformation and volcanism facilitated the supply of abundant volcanoclastic sediments resulting in rapid but punctuated basinal aggradation to the south and east transgressive regressive cycles were marked by the inter digitation of paralic shallow marine and alluvial strata lonestones dropstones are common within the marine deposits and are attributed to ice rafting indicative of a cold climate depositional regime two basin wide chronostratigraphic units the p tuff bed and the harrow creek superseam have been used to evaluate the facies architecture of the stratigraphic interval they enclose the lithofacies mosaic of the 25 75 m thick sequence has been examined by means of 26 widely distributed coreholes and two detailed district scale studies based around the moranbah goonyella and german creek minesites eight alluvial shallow marine facies associations have been recognised their architectural and temporal relationships allow the accurate reconstruction of the coal bearing depositional system two dissimilar stacked depositional systems tracts a organics and b clastics are recognised the p tuff bed is enclosed by facies of tract a forming a thick low ash coal bearing interval which was emplaced essentially synchronously across the basin it represents a time of clastic sediment starvation when basin wide peat mire accumulation prevailed four similar extensive coal bearing intervals within the moranbah coal measures are also considered to represent basin wide episodes of peat accumulation this pattern is in strong contrast to traditional views of coal measure development which argue that coals formed within a contemporary facies mosaic in which fluvial channels levees and crevasse splays were also represented the second depositional systems tract b is characterised by clastic packages dominated by large scale up to 4 km wide and 50 m thick sandstone bodies deposited by low sinuosity trunk river systems flanked by substantial crevasse splay deposits up to 3 km wide and 30 m thick it represents the product of catastrophic flooding events the cyclothemic succession of systems tracts a and b is interpreted in terms of eustatic sealevel cycles the tract a coal bearing intervals represent relative sealevel lowstands systems tract b represents relative sea level highstand with its lower interval at german creek to the south consisting of paralic and marine facies the cycles had durations in the order of 400 to 600 ky and are considered to represent 4th order sealevel cycles of the permian period

evidence of fire in australian cenozoic rainforests abstract new palynological analysis of the middle eocene to middle miocene latrobe group coals of the gippsland basin in australia sheds new light on fire adaptation in australia s modern flora the distribution of charcoal and fire prone flora within brown coals is entirely controlled by facies and the paleoenvironments within the peatland and does not result from drier climates as has been previously suggested there is therefore no evidence of climatic drying from this cenozoic peatland record charcoal and fire prone floras are associated with emergent and meadow marsh environments that produce darker coal lithotypes counter intuitively the low nutrient and fire prone environments that fringed the ever wet rainforests of the latrobe group peatlands may have represented an ideal setting for southeastern australia s modern fire adapted and sclerophyllous flora i e eucalyptus and banksia to evolve in

dynamic crystallization experiments on the angra dos reis achondritic meteorite abstract with the recent discovery of angrite meteorites in the antarctic collection which clearly have a melt origin the hypothesis that angra dos reis ador itself is a cumulate is being reconsidered a recent model suggests that ador is a porphyry not a cumulate dynamic crystallization experiments have been conducted to determine whether a melt of ador composition can crystallize with porphyritic textures at reasonable cooling rates under appropriate heterogeneous nucleation conditions the nucleation conditions were varied by melting the starting material at different degrees of superheat porphyritic textures were produced if nuclei are absent from the melt and embryos are few in number if some degree of supercooling is developed while the embryos are growing to critical size the phenocrysts grow with skeletal shapes fassaitic pyroxene grows over a large temperature interval before the appearance of kirschsteinite spinel and a pyroxferroite like phase alternatively if the nucleation density is high and irregularity distributed at the beginning of cooling a granular texture very similar to ador is produced in this case the large fassaites would grow later and poikilitic enclose the early formed granular fassaite the phases present and their composition depend on the oxygen fugacity and a complex redox history for ador can be inferred olivine is not present in quantities compatible with ador and kirschsteinite appears to have been stabilized kinetically in the experiments while a volcanic or hypabyssal history for ador is possible based on the experiments the presence of olivine particularly as a phenocryst remains unexplained

synneusis of kilauea iki olivines olivine phenocrysts in the picritic scoria that erupted from kilauea iki in 1959 occur as glomeroporphyritic aggregates of 2 16 crystals the compositions and three dimensional textures of the olivines vary within an aggregate and within individual lapilli the attachment of crystals from different environments indicates that these aggregates formed by synneusis the swimming together of crystals most of the crystals are attached along faces with their a crystallographic axes parallel and their c axes either parallel or perpendicular so that the structural mismatch and interfacial energy are minimized observed facial attachments are consistent with fluid dynamical interactions of crystals falling with their large 010 faces horizontal the aggregates formed in a liquid rich magma rough computations suggest that the minimum aggregation time could be on the order of minutes aggregation of very small crystals suggests that the yield strength was less than 3 dynes cm 2 the textures of the aggregates are similar to those of cumulate peridotites

coal facies in a cenozoic paralic lignite bed krabi basin southern thailand changing peat forming conditions related to relative sea level controlled watertable variations abstract the cenozoic krabi basin in the southern part of peninsular thailand contains about 112 million tons proven coal reserves at present coal is only produced from the bang mark mine located in the southern part of the basin where the main lignite bed is 7 20 m thick the lignite bed occurs in an overall paralic succession the present paper investigates the depositional conditions of an approximately 8 m thick lignite bed main seam in the bang mark mine using organic petrography including maceral ratios and geochemistry the results are further interpreted in a sequence stratigraphic context the lignite is of low rank and is completely dominated by huminite indicating generally oxygen deficient conditions in the precursor mire very low inertinite contents suggest rare occurrences of wildfires the lower part of the lignite bed represents a topogenous fresh water peat mire with open water areas that in few cases may have experienced influx of saline water the peat mire was subjected to periodic inundations and deposition of siliciclastics tissue preservation was relatively poor the upper part of the lignite bed represents a slightly domed fresh water ombrogenous peat mire with a stable watertable and a balance between peat accumulation and accommodation space creation that favoured preservation of plant tissues in general the mire vegetation changed from less woody in the topogenous mire to more arborescent in the ombrogenous mire where plants with suberinised wood cell walls also were more frequent decompacted the lignite bed corresponds to a minimum 11 m thick peat deposit that records from 22 000 to 55 000 years of peat accumulation watertable rise in the peat mire was controlled overall by relative sea level rise in a sequence stratigraphic context the lignite bed overlies a terrestrialisation surface tes sensu diessel 2007 and the lowermost part records peat formation during a falling watertable and a decreasing accommodation peat accumulation ratio terrestrialisation an accommodation reversal surface ars sensu diessel 2007 indicates a change to paludification style of peat formation characterised by rising watertable and a high accommodation peat accumulation ratio another ars marks a gradual change to a situation with a balanced accommodation peat accumulation ratio the overall watertable rise throughout peat formation but at a gradually slower rate from base to top suggests that the lignite bed could be located in the late transgressive systems tract tst

a review of tertiary brown coal deposits in australia their depositional factors and eustatic correlations the paleogeographical setting sequence stratigraphy and timing for six tertiary brown coal deposits along the southern seaboard of australia indicate a concentration of major coal forming phases to periods of significant coastal onlap coupled with frequent sea level oscillations

origin of differentiated lavas at kilauea volcano hawaii implications from the 1955 eruption kilauea s 1955 eruption was the first major eruption longer than 2 days on its east rift zone in 115 years it lasted 88 days during which 108 106 m3 of lava was erupted along a discontinuous 15 km long system of fissures a wide compositional range of lavas was erupted including the most differentiated lavas 5 0 wt mgo from a historic kilauea eruption lavas from the first half of the eruption are strongly differentiated 5 0 5 7 wt mgo later lavas are weakly to moderately differentiated 6 2 6 7 wt mgo previous studies using only major element compositions invoked either crystal fractionation macdonald and eaton 1964 or magma mixing wright and fiske 1971 as models to explain the wide compositional variation in the lavas to further evaluate these models detailed petrographic mineralogical and whole rock major and trace element xrf analyses were made of the 1955 lavas plagioclase and clinopyroxene in the early and late lavas show no petrographic evidence for magma mixing olivines from both the early and late lavas show minor resorption which is typical of tholeiitic lavas with low mgo contents core to rim microprobe analyses across olivine augite and plagioclase mineral grains give no evidence of disequilibrium features related to mixing instead plots of an ab vs distance from the core d and fo vs d 4 5 generated essentially linear trends indicative of simple crystal fractionation least squares mass balance calculations for major and trace element data using observed mineral compositions yield excellent results for crystal fractionation sum of residuals squared 0 01 for major elements and 5 for trace elements magma mixing produced less satisfactory results especially for cr furthermore trace element plots of zr vs sr cr and a12o3 generate curved trends indicative of crystal fractionation processes there is no evidence that mixing occurred in the 1955 lavas instead the data are best explained by crystal fractionation involving a reservoir that extends at least 15 km along kilauea s east rift zone a dike was intruded into the rift zone from the summit reservoir eight days after the eruption started instead of causing magma mixing the dike probably acted as a hydraulic plunger forcing more of the stored magma to be erupted

influence of climate and hydrology on carbon in an early miocene peatland abstract our understanding of the hydrodynamic response of peatland to climate change is restricted to the holocene which confines our knowledge of the fundamental controls on this important carbon reservoir to recent sedimentary successions to understand the interaction of peatland hydrodynamics climate and the carbon cycle on longer time scales a 95 4 m record from lower miocene lignite from the gippsland basin australia is considered 13 c and colour records for the lignite were created by analysing samples every 0 1 m solid state 13 c nmr results indicate that lignite colour is related to the relative abundance of aliphatic carbon the lack of a direct correlation between colour and 13 c demonstrates that the 13 c signal has not been significantly influenced by the diagenetic processes that produce the colour an offset correlation occurs between 13 c and colour with the degree of offset decreasing from 4 5 m at the base to about 0 m at the top this offset is considered to represent a zone of surface influence that extends up to 20 m below the peat surface using numerical modelling we demonstrate that this zone of surface influence and its gradual decline in thickness could arise as a consequence of enhanced fluid flow in regions of high tensile stress within the unconfined peat body the removal of lignin and its derivatives from the zone of surface influence will be favoured by cooler drier periods with lower sea level and high hydraulic gradients across the peatland therefore in the early miocene this peatland acted as a carbon source during global cooling

decadal time gaps between mafic intrusion and silicic eruption obtained from chemical zoning patterns in olivine abstract intrusion of mafic magma in a silicic crustal reservoir has been reported in numerous studies of subduction related volcanoes and is considered a main process for triggering explosive eruptions and for transferring geochemical signatures from the mantle to the crust here we determine the timescales between mafic silicic encounters and eruption by exploiting the fact that during such interactions magmas exchange crystals and their mineral compositions will strive to equilibrate to the new environmental conditions specifically we model the fe mg zoning patterns of olivine found in the dacites andesite and quenched mafic inclusions of the holocene zoned eruption of volcan san pedro 36 s chilean andes the san pedro eruption is an example where mixing between silicic and mafic magmas produced intermediate compositions e g andesite at depth in the magma reservoir for modeling the compositional profiles we took into account the anisotropy of fe mg diffusion in olivine and also the effects of diffusion in multiple dimensions aspects that have been largely neglected in previous works the retrieved timescales for olivine melt equilibration by diffusion display an array ranging from 1 year for the most silica rich dacite to 50 years for the andesite this array of timescales rather than a single value provides new insight into the details of mafic silicic mixing at depth they reveal processes that occur on a longer timescale than the days to weeks time gap for cases where the mafic intrusion triggered the eruption and they might be associated with the instances where seismic activity or significant inflation of the volcanic edifice was not immediately followed by eruption on the other hand the year to decade timescales that we report for producing magmas of intermediate composition e g andesites are much shorter than the 10 3 10 5 years inferred from u series disequilibria data for igneous differentiation by closed system fractionation to produce similar magma compositions at subduction zones

the theory of zoning patterns in magmatic minerals using olivine as an example a theory of simple zoned growth in magmatic minerals is developed using olivine as an example the law of growth in absolute feo mgo space has the form y0 ys a x0 xs k where x refers to feo y refers to mgo and the subscript s refers to the solid phase x0 and y0 are the starting amounts in the liquid a is a constant which characterizes each individual liquid line of descent and k is the distribution coefficient consideration of this equation shows that the size of the local system is the most important parameter affecting the shape of the zoning pattern the starting ratio mgo feo is the next most important magmatic parameter and k is the most tightly constrained and therefore the least important parameter affecting the pattern of zoning an empirical relationship plotting mgo feo in the crystal versus the volume of the crystal linearizes the zoning pattern allowing prediction of the fictive volume of the crystal and the diameter of the system from which the crystal grew model calculations show an error of 7 or less in determining the linear dimensions of the system on a linearized plot the starting composition of the crystal may be determined by extrapolation even if the section does not go through the center analysis of zoning profiles using this theoretical law of growth may be useful in studies of crystal growth rates nucleation mechanisms diffusion rates and viscosity of natural melts

olivine phenocrysts of hawaiian olivine tholeiite and oceanite olivine phenocrysts of hawaiian tholeiites display a variety of textures and a variation in composition which is due to supercooled crystallization the highest forsterite content measured is 91 and the highest magnesia content estimated for a tholeiitic liquid is 17 using the olivine geothermometer the liquid of this composition may be either a primary magma or a primitive magma it is not yet possible to specify any particular composition range for the primary hawaiian tholeiites

biogeographic ecological and stratigraphic relationships of the miocene brown coal floras latrobe valley victoria australia abstract palaeobotanical studies of the brown coal deposits of the latrobe valley have contributed significantly towards an understanding of the age of the deposits existing climatic conditions and detailed depositional environments this paper re assesses some past reconstructions for the early to mid miocene coals using recent information on plant distributions and their bioclimatic significance and on a marine incursion model for coal lithotype formation the brown coal flora is composed overwhelmingly of rainforest taxa that presently cover a range of different environments within the australasian region the application of a bioclimatic prediction model to these taxa allows the construction of consistent and quantitative estimates of climates during coal forming phases it is considered that rainfall in the area was more than twice the 850 mm received today with significant seasonal variation the mean annual temperature estimate of about 19 c indicating a mesothermal or subtropical environment is some 2 5c higher than present and higher than previous estimates it does however correspond with sea surface temperature estimates for the southern ocean at this time the original model of lithotype formation which suggests that lithotypes conform to a successional sequence from open water in the lightest coloured lithotypes to raised bog in the darkest lithotypes is considered to be inconsistent with the evidence for lightening upwards sequences within the coals a central feature of the proposed marine incursion model of coal formation the two models are reconciled to some degree by a reinterpretation of the palaeobotanical data and by the postulation of climatic rather than autogenic successional control over lithotype formation

the origin of lithotype cycles in oligo miocene brown coals from australia and germany abstract brown coal colour lithotype cycles range from 10 to 30 m thick in oligo miocene coals of the latrobe valley gippsland basin australia similar colour lithotype cycles occur in the lusatia german miocene brown coals in both the latrobe valley and germany the cycles often display well developed colour lightening upward trends as defined by new colourimetry measurement the typical lithotype cycle boundary is abrupt between light below and dark lithotype above geological geochemical palynological and macrofossil evidence is consistent with a relative drying terrestrialisation upward depositional model for each cycle and the overlying dark lithotype represents renewed peat accretion the dark lithotype may include charcoal near the cycle base explained by the fire prone and highly flammable nature of the herbaceous reed wetlands in both the german and australian coals wetter darker lithotypes are characterized by a gymnosperm paleoflora while drier lighter lithotypes are characterized by angiosperms in the german rhenish miocene brown coal exposed in large open cut mines at garzweiler and hambach a 1 0 m spaced sampling and colourimetry measurement program shows lightening upwards cycles for the morken seam frimmersdorf a seam frimmersdorf b seam and for the garzweiler ii seam at hambach where the 60 m thick main seam includes amalgamations of frimmersdorf a frimmersdorf b and garzweiler i ii iii seams the lightening upwards trends provides a means of stratigraphic subdivision the palaeogeographic setting for latrobe valley and german brown coals is similar in latrobe valley the seams split and thin to the east into marine facies in the rhenish and lusatia brown coals they also split and thin to the north into marine facies the two rhenish mines at hambach and garzweiler respectively typify end members of this palaeogeography the hambach mine is located in a distal location where sulphur content is negligible the garzweiler mine is located in a proximal location to the marine boundary where sulphur content is higher the colourimetry and facies succession suggest german brown coal deposition followed a similar cyclic depositional succession to the latrobe valley and that this succession may be fundamental in all thick coal seams

cyclic floral succession and fire in a cenozoic wetland peatland system abstract the cyclic succession of brown coals in the latrobe valley gippsland basin australia records an exceptional floral and charcoal record from the late oligocene to middle miocene new palynological geological and charcoal data are consistent with existing colourimetry carbon isotope and organic geochemical and palaeobotanical data indicating that the repeated lithotype cycles represent relative drying terrestrialization based on this detailed palynological study the vegetation succession within the latrobe valley peatlands is interpreted to have begun with a fire prone emergent marsh of bulrushes typhaceae which grades landward into a fire prone meadow marsh of rushes restionaceae heaths ericaceae and coral ferns gleicheniaceae this marsh environment then developed into a forested bog with gymnosperms e g the podocarpaceae dacrycarpus and dacrydium as the dominant trees until an ombrogenous forest bog developed predominantly consisting of angiosperms e g nothofagus quintinia the similarity between vegetation successions in new zealand and the lightening upwards cycles from the latrobe valley coals suggests that new zealand s modern vegetation communities represent a floral analogue for the successions preserved in the latrobe valley coals high abundances of micro and macro charcoal recorded in the darker lithotypes within the lithotype cycles of the m1b and m2a seams suggest that the latrobe valley peatlands were subject to repeated fires during the late oligocene to early miocene

was the oligocene miocene a time of fire and rain insights from brown coals of the southeastern australia gippsland basin abstract lithotype cycles ranging from 10 to 30 m thick in the brown coals of the latrobe valley gippsland basin australia display well developed lightening upward trends cycle tops are characterized by abrupt and unconformable boundaries with the overlying cycle geological geochemical palynological and macrofossil evidence is consistent with a relative drying terrestrialization upward depositional model for the cycles the abundance of charcoal in dark lithotypes near the cycle bases is explained by the fire prone and highly flammable nature of the herbaceous reed wetlands in common with similar modern wetlands in modern australasia in which the dark lithotypes are suggested to have formed this together with the greater preservation potential of charcoal in subaqueous environments results in the wettest facies of the latrobe valley coals having the highest charcoal contents despite prevailing warm wet climate conditions and the predominance of rainforests that are suggested to have characterized the cenozoic of southern australia some swamp taxa were clearly already pre adapted to tolerate fire and are likely to have been the ancestors of the fire adapted floral communities of modern arid australia

microstratigraphy of a miocene layered phosphatic pebble from the western margin of south africa abstract detailed microstratigraphy and geochemistry of a single layered phosphaticpebble from the southern rocky plateau at the head of the cape canyon on thewestern margin of south africa are utilized to reveal a complex interplaybetween deposition erosion and authigenesis in the miocene the phosphaticpebble has three micrite and carbonate uorapatite cemented layers separatedby fe rich hardground surfaces the layers contain a diverse grain assemblageof reworked glauconite phosphorite detrital quartz and biogenic carbonate overlapping sr isotope derived ages of point drilled samples from the threelayers range from 19ae1to17ae6 ma although a single point near the outer edge ofthe uppermost layer has a sr age of 12ae8to10ae4 ma and a reworked bivalveshell fragment from the middle layer has a sr age of 26ae3to24ae6 ma themicrostratigraphy of the phosphatic pebble provides evidence of multiplebaturin cycles where periods of deposition and carbonate uorapatiteauthigenesis are followed by reworking erosion and precipitation of ironoxide hardground surfaces the condensed microstratigraphy of the pebble isconsistent with the regional depositional history of the area and indicatessigni cant uctuations in the depositional environment related to changes insea level sediment supply and upwelling along the western margin ofsouthern africa during the early to middle miocene keywords continental shelf hardground miocene phosphorite sea level sr isotopes introductionthe geological evolution of passive margins islargely governed by changes in relative sea level recording both changes in global sea level and thelocal effects such as tectonic movement subsi dence and sediment supply miller et al 1997 1998 2005 lavier et al 2001 the geologicalevolution of the passive western margin of south ern africa is poorly constrained largely due to anabsence of well preserved sedimentary recordswithin the highly condensed cenozoic marginsuccession pether et al 2000 the late ceno zoic evolution is characterized by marine erosionand low sediment input dingle 1973 siesser d wigley compton 2006 uppercenozoic sediments occur as a coast parallel lenson the outer shelf and continental slope but athin cover extends seawards into the cape basin dingle 1973 dingle et al 1983 a veneer ofmiddle to upper neogene sediments with amaximum thickness of several tens of metres ispreserved above the cretaceous sedimentarysuccession on the inner to middle shelf rogers bremner 1991 compton et al 2002 wigley compton 2006 these cenozoic offshore andadjacent onshore sedimentary records are oftenincomplete and controversial with little consen

coal facies studies in australia despite the economic importance of coal to the australian economy detailed studies of controls on variation in coal type are remarkably few however important contributions have been made in the understanding of coal facies development tertiary lignite deposits of the gippsland basin provide key insights into the development of lithotype cyclicity and its relationship to relative sea level changes with individual paling up cycles being correlated to parasequences studies of permian hard coals have identified relationships between coal type and surrounding sediments unfortunately these relationships have been widely over interpreted in a manner that has diminished their real value

chronometry and speedometry of magmatic processes using chemical diffusion in olivine plagioclase and pyroxenes the magmatic processes that fuel volcanism crustal growth ore formation and discharge of volcanic gases and aerosols to the atmosphere occur across a range of timescales from millions of years to just a few seconds for example the production of new oceanic crust at mid ocean ridges is a near continuous process that can operate in any one ocean basin on timescales of more than 100 m y however the driving force for such processes is the spreading of the ocean plates that happens on a cm yr timescale at the other end of the spectrum explosive volcanic eruptions involve the ascent and fragmentation of magma at velocities of the order of 100 m s such that the journey from a magma chamber to an ash cloud may take place in a matter of minutes in this case the driving force is the rapid expansion of magmatic gas in response to changes in pressure at intermediate timescales magmatic processes may give rise to hydrothermal ore deposits on timescales of less than a million years for an individual deposit while growth of giant granite batholiths may require piecemeal assembly of magma batches on timescales of a few million years although each of these processes has a characteristic time averaged timescale on which it operates this is typically the end result of one or more natural processes that operate on much shorter timescales for example mid ocean ridges do not extrude magma continuously onto the ocean floor mineralising fluids do not discharge continuously through the shallow crust and granitic magmas do not dribble continuously into evolving batholithic chambers in some cases it is the long term timescales that are important for example the spreading rate of ocean basins in others it is the short term timescales that are important for example the episodic growth of lava domes at active volcanoes although

time scales of magmatic processes from modeling the zoning patterns of crystals the advent of polarized light microscopy in the middle of the 19th century allowed mineralogists and petrologists interested in igneous rocks to recognize the widespread occurrence of fine scale heterogeneities in the optical properties of minerals e g see young 2003 for details the interpretation of mineral zoning patterns as archives of magmatic processes has been with us for some time e g larsen et al 1938 tomkeieff 1939 the development of the electron microprobe in the 1960 s allowed mineral zoning profiles to be quantitatively analyzed and modeled e g bottinga et al 1966 moore and evans 1967 enhanced textural observations permitted recognition of many kinds of detailed structures during the growth and dissolution of magmatic minerals fig 1 e g anderson 1983 pearce and kolisnik 1990 and these processes were also explored using experimental and numerical models e g albarede and bottinga 1972 lofgren 1972 kirkpatrick et al 1976 loomis 1982 major element zoning patterns are routinely measured and with the arrival of the ion microprobe the identification of heterogeneous distribution of trace elements opened the window for more realistic and sophisticated scenarios and models fig 1 e g kohn et al 1989 blundy and shimizu 1991 singer et al 1995 we now measure abundances of naturally occurring isotopes at the scale of tens of micrometers e g davidson et al 2007a ramos and tepley 2008 and this allows in situ dating of crystals e g cooper and reid 2008 figure 1 a nomarski dic image of a plagioclase crystal from a gabbroic xenolith of volcan san pedro costa et al 2002 the crystal shows a well defined core and a rim separated by an oscillatory zoned interval ion microprobe analysis pits and the trace of the electron microprobe traverse between the pits are evident b major

early pennsylvanian ombrotrophic mire of the prokop coal upper silesian basin what does it say about climate abstract the lower pennsylvanian kinderscoutian prokop coal coal no 40 the erosional remnant of which covers about 5000 km 2 is the thickest seam of the upper silesian basin situated along the czech polish border this basin wide coal is unusual in its thickness and high inertinite and very low ash contents in the czech sector this coal merges with the overlying coal no 39 into a single 9 to 15 m thick seam maceral analyses of an approximately 11 m thick section of these two merged coals show changes in the proportion of vitrinite 24 7 88 0 and inertinite 8 5 56 8 in cycles between 50 and 190 cm thick the increase of inertinite in the lower part of coal cycles coincides with a dulling upward trend which records a drying upward succession due to a slowing of accommodation rate relative to plant biomass productivity this succession is interpreted as a transition from rheotrophic to ombrotrophic conditions the brightening upward succession in the upper part of coal cycles records a wetting upward trend due to water table rise resulting in restoration of rheotrophic conditions that supported humification under the regional ground water table the sudden shift from inertinite rich to vitrinite rich coal at the base of brightening upward successions points to a period of degradation and lowering of the peat dome the coal cycles within the studied seam section probably preserve a succession of spatially overlapping but genetically independent mires bounded by degradation surfaces the alternation between mires with contrasting hydrological regimes is interpreted as a record of base level fluctuations of climatic causation of sub milankovitch periodicities early pennsylvanian climate for various stages of mire development is inferred from analogy with modern tropical mires in se asia

a review and reinterpretation of evidence concerning the origin of victorian brown coal abstract the nature of the depositional environments which led to the formation of the very extensive victorian brown coal deposits located in southeeastern australia has been the subject of numerous publications previous publications on this subject have suggested that these coals were laid down in an extensive series of peat swamps similar to the florida everglades u s a one of the central premises of this depositional model has been that lithotype formation is dependent on the degree of inundation of the original peat forming environment specifically it proposes an inverse relationship between the degree of inundation and the lightness of colour of the resulting lithotype with the light and pale lithotypes being deposited in fully inundated environments in this manuscript the evidence on which this depositional model is based and other data from a variety of disciplines relevant to the question of the nature of the depositional environments of these coals is reviewed the resulting synthesis of data has led the present authors to conclude that previous depositional models cannot fully account for the observed chemical physical and geological characteristics of these coals therefore a new depositional model is proposed which seeks to account for these observed characteristics it is concluded by the present authors that deposition of these coals probably took place in an extensive and long lived series of ombrogenous raised or domed forested peat swamps structurally analogous to modern peat accumulations in se asia further it is suggested that lithotype formation is governed not by the degree of inundation of the original peat forming environments but rather by the degree of aerobic degradation experienced by the initial peat accumulations with pale and light coals representing the products of the most severely degraded peats

saturn s cloud structure inferred from cassini iss abstract using high resolution cassini iss images with wavelengths ranging from the ultraviolet to the near infrared we have retrieved saturn s atmospheric aerosol structure and properties for a broad range of latitudes in the southern hemisphere the observations are consistent with two distinct layers of haze above a scattered cloud each layer is characterized by a vertical location an optical thickness and an effective mean particle size all of which vary with latitude the tropospheric haze is optically thickest and extends to the greatest heights 40 mbar over the equator its top surface is at significantly greater depths 150 mbar at mid latitudes the height of the haze correlates well with position of the tropopause as indicated by the temperature field beneath this haze we find a scattered denser cloud responsible for small scale contrasts at an average depth of 1 75 0 4 bar with some features as deep as 2 5 bar or greater

inertinite rich tertiary coals from the zeya bureya basin far eastern russia selected tertiary coals from the zeya buryea basin far eastern russia were investigated for aspects of their coal type rank depositional environment and post depositional history the coals have been examined in outcrop lithotype logging microscopically maceral reflectance and fluorescence and geochemically proximate analysis two laterally extensive coal bearing horizons occur one of palaeocene age and the other of early miocene age the palaeocene coals were investigated in active open cut mines at raichikhinsk and yerkovtsi and the early miocene deposit in an abandoned open cut mine at cergeyevka palaeocene coals at raichikhinsk and yerkovtsi were indistinguishable from each other macroscopically microscopically and geochemically the deposits were sufficiently coalified that brightness logging could be undertaken dull coals with numerous fusainous wisps were dominant four dulling up sequences which represent stacked peat deposits were observed at raichikhinsk at yerkovtsi only a small section of the middle of the seam which was mostly dull and muddy coal was investigated petrographically these coals were dominated by inertinite group macerals which is unusual in non gondwanan coals and rare in the tertiary rank classification was problematic with volatile matter vm content of vitrain daf macroscopic appearance and microscopic textures suggesting subbituminous b rank but carbon content moisture content and specific energy indicating a lignite rank notwithstanding complications of rank estimates of the maximum range burial depths were calculated taking the vm daf content of vitrain as 48 burial depth estimates range from 900 m for a high geothermal gradient and long heating time to a maximum of 3300 m for a low geothermal gradient and short heating time these estimates are maxima as the coal rank may be lower than implied by the vm the cergeyevka deposit is a soft brown coal limited sampling of the upper most portion indicated a high moisture content 75 daf and an unusual hydrogen rich geochemistry lack of identifiable liptinites using either reflected light or fluorescence microscopy suggested a significant bituminite component otherwise the coals appear to be typical for the tertiary an estimate of 125 m maximum burial depth was obtained using the bed moisture content of the coal which is around the present burial depth comparison of present day thicknesses with inferred burial depths suggests that at least 500 m of section is missing between the palaeocene coals and the early miocene coals palaeoenvironmental considerations suggest that fire played a significant role in the accumulation of the peats at raichikhinsk and yerkovtsi at cergeyevka peat accumulation ended by drowning of the mire two tuff beds were recognised within the seam at raichikhinsk and one in the seam at yerkovtsi correlation of the tuff beds is uncertain but they should prove useful in regional coal seam correlation and interpreting coal depositional environments geochemical analysis by xrf was complicated by high loss on ignition loi values despite extensive alteration an acid igneous source is implied from the presence of free quartz and tio2 al2o3 ratios of 0 02 to 0 05

a 1 16 ma record of carbon accumulation in western european peatland during the oligocene from the ballymoney lignite northern ireland the oligocene ballymoney lignite in northern ireland is one of the thickest lignites in europe and provides the potential for comparing holocene and pre holocene peatland evolution and its response to long term climate change on time scales much greater than 10 ka samples were collected from 50 m of lignite and analysed for 13 c spectral analysis of the 13 c record reveals that the record contains significant frequencies at 0 21 m 1 and 1 12 m 1 these cycles are interpreted as the c 100 ka eccentricity and 20 ka precession cycles respectively these cycles were then tuned and the duration was determined as 1 16 ma with a carbon accumulation rate of 27 g c m 2 a 1 if long term changes in lignite 13 c are related to changes in the 13 c of the exogenic carbon reservoir and if the lignite chattian age is accepted then the lignite probably formed between 24 6 and 25 8 ma comparison of the estimated carbon accumulation rate with other cenozoic peatland carbon accumulation rates indicates that this rate appears to be insensitive to changes in the concentration of atmospheric co 2