biomarker and carbon isotope variation in coal and fossil wood of central europe through the cenozoic abstract carbon isotope analyses of terrigenous organic matter are often used to reconstruct changes in the isotopic composition of upper ocean and atmospheric carbon reservoirs carbon isotope values from tree rings fossil wood and coal matrices have been related to climatic change e g temperature humidity via water use efficiency of land plants in this study we report on carbon isotope analyses on low rank coal deposits of the alpine realm and middle german lignite district covering the early eocene to pliocene time interval fossil wood and extracted wood cellulose from gymnosperms and angiosperms respectively are used for paleoenvironmental reconstructions the trend in 13c is parallel to the carbon isotope record obtained from benthic foraminifera because both data sets sample a common reservoir in the atmosphere the evaluation of the magnitudes of 13c variations of coal caused by environmental change requires the correction of the 13c data due to the effects of different contents of lipids in the organic matter differences in biogeochemical carbon cycling varying contributions of gymnosperms versus angiosperms to peat formation and differences in 13c of atmospheric co2 the resulting carbon isotope record of coal generally co varies with the estimated variability in mean annual temperatures during the tertiary based on paleobotanical data changes in humidity and pco2 may be responsible for deviations between the isotopic trend and the paleotemperature curve during the miocene the obtained temperature coefficient for 13c of c3 plants of about 0 3 c is in agreement with the results of previous studies

temporal variation of large intraplate earthquakes in coupled subduction zones the focal mechanisms of intraplate earthquakes within subducting lithosphere are frequently used to infer large scale stress regimes induced by slab pull bending or unbending and lateral segmentation and undulations of the slab numerous studies have further postulated that the intraplate activity is influenced by transitory regional stress regimes such as those associated with interplate thrust events temporal variations of the latter type may potentially play an important role in assessing regions of uncertain seismic potential and possibly even in earthquake forecasting a systematic analysis of 1130 focal mechanisms for intraplate earthquakes with m b 5 0 in the depth range 0 300 km is conducted for nine circum pacific subduction zones all of which are known to have large interplate thrust events the spatial and temporal relationships of the earthquakes within the subducting slab to the large thrust events in each region are appraised the earthquake catalog assembled contains all published focal mechanisms and is probably complete for m b 6 5 for the years 1963 1986 for many of the localized regions considered in detail the catalog is complete to lower thresholds of m b 6 0 or m b 5 5 this analysis provides compelling evidence for a temporal link between large interplate thrust activity and intraplate seismicity for the seismically coupled regions considered here outer rise compressional events have occurred prior to several large thrust events or are associated with seismic gaps while outer rise tensional events generally only follow interplate ruptures in the intermediate depth range large down dip tensional events generally precede interplate thrusts and are often concentrated at the down dip edge of the coupled zone a transition to down dip compressional stress or diminished tensional activity at intermediate depth is observed after several large thrust events e g 1960 chile 1974 peru 1957 aleutian 1971 new britain these examples support the notion that the intraplate stress environment responds viscoelastically to the temporally varying interplate stress regime assuming that this concept is correct the seismic potential of several seismic gaps is considered on the basis of both outer rise and intermediate depth earthquake activity

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

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

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

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

mineralogy petrography and organic geochemistry of miocene coal seams in the kinik coalfield soma basin western turkey insights into depositional environment and palaeovegetation abstract the kinik coalfield is located in the south westernmost part of the soma basin in western turkey and hosts all three miocene coal seams from bottom to top km2 km3 and kp1 this study presents the coal petrographical mineralogical and organic geochemical features of samples collected from two deep cores samples from seam km2 generally display low ash yields and high toc content whereas the km3 and kp1 seams are characterized by relatively high ash yields and low toc values furthermore total s content of the kp1 is very high up to 7 0 on dry basis the maceral composition the coal facies diagrams and the distributions of n alkanes and diterpenoids indicate changes of depositional conditions and vegetation in the palaeomires of the km2 seam during early miocene the precursor peat of km2 seam started accumulating under limnotelmatic conditions followed by pure telmatic ones consequently initial mixed vegetation was replaced by a conifer dominant assemblage in the palaeomires in the upper parts of the km2 seam the coal facies indices and high concentrations of n alkanes along with the relatively low di di tri terpenoid ratios are indicators of the higher contribution of herbaceous species and minor abundance of conifers in the palaeomires of km3 and kp1 seams nevertheless the mineralogical composition of the km3 and kp1 seams indicate increased clastic input and alkalinity in the palaeomires that could reduce preservation of organic matter thus high ash yields and low toc were obtained from these seams in addition sulphate rich water supply along with synchronous pyroclastic air borne input into the palaeomires caused elevated total s content of the kp1 seam

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

seismology energy radiation from the sumatra earthquake we determined the duration of high frequency energy radiation from indonesia s great sumatra andaman earthquake 26 december 2004 to be about 500 seconds this duration can be translated into a rupture length of about 1 200 km which is more than twice as long as that inferred from body wave analyses performed soon after the event our analysis was able rapidly to define the extent of rupture thereby aiding the assessment of seismic hazard in the immediate future

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

outer rise earthquakes and seismic coupling outer rise earthquakes can be separated into two basic categories based on focal mechanism compressional and tensional events reflecting compressional and tensional outer rise stress regimes we propose a model that connects the stress regime in the outer rise to the behavior of large subduction earthquakes and explains the focal mechanisms and both the temporal and spatial occurrence of outer rise earthquakes we find that compressional outer rise events tend to occur oceanward of seismic gaps in seismically coupled subduction zones or equivalently just prior to large subduction zone earthquakes the compressional stress regime is probably caused by slip in adjacent subduction zone segments there are two modes of occurrence for tensional outer rise earthquakes depending on whether they occur in coupled or uncoupled subduction zones in coupled subduction zones tensional events tend to occur after large subduction events as tensional stress from slab pull is temporarily transmitted to the outer rise in subduction zones that are inherently uncoupled tensional events can occur at any time therefore in uncoupled subduction zones the outer rise is always in tension and only tensional outer rise events occur there while in coupled subduction zones the outer rise is in a compressional state prior to large subduction earthquakes and a tensional state afterwards due to the large displacements

deeper groundwater chemistry and geochemical modeling of the arsenic affected western bengal basin west bengal india abstract a regional scale hydrogeochemical study of a 21 000 km2 area in the western bengal basin shows the presence of hydrochemically distinct water bodies in the main semiconfined aquifer and deeper isolated aquifers spatial trends of solutes and geochemical modeling indicate that carbonate dissolution silicate weathering and cation exchange control the major ion chemistry of groundwater and river water the main aquifer water has also evolved by mixing with seawater from the bay of bengal and connate water the isolated aquifers contain diagenetically altered water of probable marine origin the postoxic main aquifer water exhibits overlapping redox zones metal reducing sulfidic and methanogenic indicative of partial redox equilibrium with the possibility of oxidation in micro scale environments the redox processes are depth dependent and hydrostratigraphically variable elevated dissolved as in the groundwater is possibly related to fe iii reduction but is strongly influenced by coupled fe s c redox cycles arsenic does not show good correlations with most solutes suggesting involvement of multiple processes in as mobilization the main river in the area the bhagirathi hoogly is chemically distinctive from other streams in the vicinity and probably has little or no influence on deep groundwater chemistry arsenic in water of smaller streams jalangi and ichamati is probably introduced by groundwater discharge during the dry season

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

seismology speed and size of the sumatra earthquake we now have a clearer picture of the seismic features of last year s gigantic event our seismological results reveal that indonesia s devastating sumatra andaman earthquake on 26 december 2004 was 2 5 times larger than initial reports suggested second only to the 1960 chilean earthquake in recorded magnitude they indicate that it slowly released its energy by slip along a 1 200 km fault generating a long rupture that contributed to the subsequent tsunami now that the entire rupture zone has slipped the strain accumulated from the subduction of the indian plate beneath the burma microplate has been released and there is no immediate danger of a similar tsunami being generated on this part of the plate boundary although large earthquakes on segments to the south still present a threat

paleogeography and paleoecology of the upper miocene zillingdorf lignite deposit austria abstract the zillingdorf deposit formed during the late miocene filling of lake pannon and contains austria s largest lignite reserves two lignite seams are present and developed within frequently flooded low lying mires in near shore environments high sulphur contents are due to the influence of the brackish water body of lake pannon during peat accumulation a transgression forced the nw se trending shoreline northeastwards differences in soluble organic matter som yield and hydrocarbon content of borehole samples and woody macrofossils are related to differences in the content and composition of free lipids of microbial origin and or hydrocarbons derived from the biogeochemical degradation of plant tissue variations of pristane phytane ratios are interpreted to reflect differences in the redox conditions of the mire peatification in an acidic and aerobic environment is further reflected by the predominance of aromatic over saturated hydrocarbons the presence of an intense complex mixture in the gc traces due to biodegradation processes high ratios for diasterenes relative to sterenes and high concentration ratios of hopanes to hop 17 21 ene of the respective samples gelification of plant tissue is governed by microbial activity as indicated by the positive relationship between gelification index and hopanoids concentration the composition of terpenoid biomarkers indicates the predominance of gymnosperms over angiosperms and increasing proportions of angiosperms in the peat forming vegetation with decreasing depth in the upper seam from the sesqui and diterpenoids present in the lignite and fossil wood remnants a predominant role of species of the coniferales families cupressaceae taxodiaceae are concluded the preservation of plant tissue is governed by the presence absence of decay resistant gymnosperms a general influence of the floral assemblage on the isotopic composition of organic carbon of the lignite 13c 27 2 to 24 6 is proposed decomposition of plant tissue and biogeochemical carbon cycling is assumed to further affect the 13c values of the lignite carbon isotope data of fossil wood remnants are consistent with their chemotaxonomical classification as gymnosperms 13c between 22 5 and 24 9 and angiosperms 13c between 25 5 and 26 6 respectively the 13c data of the extracted cellulose reveal clear differences between fossil wood from gymnosperms average 13c 20 3 and angiosperms mean 13c 22 9 the higher isotopic difference of about 3 5 between cellulose and fossil wood compared to that found in modern trees is explained by the smaller effect of 13c discrimination for cellulose when compared with wood during decomposition

the motion and active deformation of india measurements of surface displacements using gps constrain the motion and deformation of india and india eurasia plate boundary deformation along the himalaya the gps velocities of plate interior sites constrain the pole of the angular velocity vector of india with respect to eurasia to lie at 25 6 1 0 n 11 1 9 0 e approximately 6 west of the nuvel 1a pole of 3 ma plate motion the angular rotation rate of 0 44 0 03 myr 1 is 14 slower than the long term rate of 0 51 myr 1 insignificant velocities between plate interior sites indicate that the exposed indian plate is stable to within 7 10 9 yr 1 the observed contraction vector across the himalaya 20 mm yr veers from n20 e in the northwest himalaya to n25 w in east nepal consistent with east west extension of southern tibet

multiple cmt source analysis of the 2004 sumatra earthquake while it is agreed that the great sumatra earthquake of december 26 2004 was among the largest earthquakes of the past century there has been disagreement on how large it was which part of the fault ruptured and how the rupture took place we present a centroid moment tensor cmt analysis of the earthquake in which multiple point sources are used in the inversion to mimic a propagating slip pulse the final model consists of five point sources with the southernmost sources accounting for the majority of the moment release the presumed fault planes of the southern sources strike northwest while those in the north strike northeast consistent with the geometry of the subduction trench slip on the fault is found to be more oblique in the north than in the south the inversion with five sources leads to a moment magnitude for the sumatra earthquake of m w 9 3 consistent with estimates from long period normal mode amplitudes

spatial variability in modern tropical peat deposits from sarawak malaysia and sumatra indonesia analogues for coal petrographic and chemical variability in two tropical low ash domed peat deposits of similar age and physiographic setting but different external morphology were examined as modern analogues for coal both occur in microtidal alluvial to deltaic plain settings support similar arborescent vegetation and have accumulated in the past 5 000 years one deposit is an extremely convex mature done with a surface that rises 10 m above river level the other is a low gradient dome rising only 3 m above river level but with a concave base up to 6 m below both deposits have been eroded by adjacent rivers yet peat in the mature dome has accumulated remote from persistent flooding and exhibits distinctive internal stratigraphy decomposed sapric peat floors the deposits and is overlain by increasingly better preserved woody hemic and a cap of coarse fibrous peat derived from less arborescent vegetation consistent flooding in the low gradient dome has maintained conditions for the accumulation of predominantly woody hemic peat which interfingers with and is overlain by oxidised sapric peat and levee derived clastic sediments peat types in both deposits exhibit distinctive polymodal textures and organo chemical signatures that correspond to botanical input and degree of decay due to the abundance of pre huminite vitrinite macerals in all peat types from these deposits megascopic and microscopic texture is a better discriminator for comparison to ancient coal types it is suggested that the upward vertical sequence of decreasing woodiness and increasing lightness in colour observed in the mature dome might best be compared to sequences observed in tertiary brown coals this typical sequence can be modified or overprinted due to flooding in the burial process

hydrogeochemical and mineralogical investigations of arsenic and humic substance enriched aquifers summary this study investigated the hydrogeochemical and mineralogical characteristics of arsenic contaminated and humic substance enriched aquifers in the chianan plain taiwan which is an endemic area for blackfoot disease bfd factorial analysis fa was used to evaluate the hydrochemical characteristics of 83 groundwater samples in the chianan plain and 462 geological core samples obtained from 9 drilling wells were collected to analyze their arsenic and iron contents the major mineral phases and chemical components were determined using x ray diffraction xrd x ray photoelectron spectroscopy xps and scanning electron microscopy and energy dispersive spectrometry sem eds partition of arsenic among various hosting solids in sediments was determined by sequential extraction the results of fa showed that the hydrochemical characteristics of the groundwater samples could be grouped by 4 factors salinization arsenic sulfide and iron arsenic was positively correlated with alkalinity dissolved organic inorganic carbon and fluorescence intensity humic acids has as v has a higher chelating affinity with has than does as iii resulting in higher as v concentrations distributed throughout the reducing environment high levels and correlations of as and has may cause bfd in the chianan plain no correlation was found between the measured and calculated redox potentials of the various redox couples the as iii as v was under a chemical non equilibrium condition the vertical distribution of the sedimentary as solid phase typically increased with depth but the aqueous as concentrations were higher in the second aquifer depth of 80 120 m arsenic content solid phase was higher in the clay silt sediments and marine formations the major minerals identified by xps and sem eds were goethite hematite magnetite pyrite and siderite agreeing with the si values calculated by phreeqc arsenic content was strongly correlated with sulfur weight r 2 0 76 p r 2 0 44 0 75 p s and fe s in the sediments was found in the transitions in the marine and non marine formations especially in the fine grains the chelation of humic complex competition for sorption sites of organic carbon reduction dissolution of fe oxides are mainly responsible for the groundwater as mobility in the chianan plain especially for the marine sequence

constraining the boundary between the sunda and andaman subduction systems evidence from the 2002 mw 7 3 northern sumatra earthquake and aftershock relocations of the 2004 and 2005 great earthquakes the 2004 m w 9 0 sumatra andaman earthquake initiated along the andaman subduction zone north of the last great sumatra earthquake along the sunda trench in 1861 during the 2005 m w 8 7 banyak islands earthquake a portion of the 1861 rupture subsequently failed the boundary between the 2004 and 2005 ruptures broadly coincides with local trench rotation and the southern edge of the andaman microplate which suggests structural control on fault segmentation aftershock relocations of the 2004 and 2005 earthquakes show little overlap and the sharp boundary between the series locates near the 2002 m w 7 3 northern sumatra earthquake we posit that these features represent the southern extent of the stable andaman microplate 50 100 km northwest of what was previously reported broadband analyses of the 2002 earthquake yield a bilateral rupture pattern that is used to model coulomb stress changes near the 2004 hypocenter to assess stress interactions along adjacent fault segments

a review of the source behaviour and distribution of arsenic in natural waters the range of as concentrations found in natural waters is large ranging from less than 0 5 g l 1 to more than 5000 g l 1 typical concentrations in freshwater are less than 10 g l 1 and frequently less than 1 g l 1 rarely much higher concentrations are found particularly in groundwater in such areas more than 10 of wells may be affected defined as those exceeding 50 g l 1 and in the worst cases this figure may exceed 90 well known high as groundwater areas have been found in argentina chile mexico china and hungary and more recently in west bengal india bangladesh and vietnam the scale of the problem in terms of population exposed to high as concentrations is greatest in the bengal basin with more than 40 million people drinking water containing excessive as these large scale natural as groundwater problem areas tend to be found in two types of environment firstly inland or closed basins in arid or semi arid areas and secondly strongly reducing aquifers often derived from alluvium both environments tend to contain geologically young sediments and to be in flat low lying areas where groundwater flow is sluggish historically these are poorly flushed aquifers and any as released from the sediments following burial has been able to accumulate in the groundwater arsenic rich groundwaters are also found in geothermal areas and on a more localised scale in areas of mining activity and where oxidation of sulphide minerals has occurred the as content of the aquifer materials in major problem aquifers does not appear to be exceptionally high being normally in the range 1 20 mg kg 1 there appear to be two distinct triggers that can lead to the release of as on a large scale the first is the development of high ph 8 5 conditions in semi arid or arid environments usually as a result of the combined effects of mineral weathering and high evaporation rates this ph change leads either to the desorption of adsorbed as especially as v species and a range of other anion forming elements v b f mo se and u from mineral oxides especially fe oxides or it prevents them from being adsorbed the second trigger is the development of strongly reducing conditions at near neutral ph values leading to the desorption of as from mineral oxides and to the reductive dissolution of fe and mn oxides also leading to as release iron ii and as iii are relatively abundant in these groundwaters and so4 concentrations are small typically 1 mg l 1 or less large concentrations of phosphate bicarbonate silicate and possibly organic matter can enhance the desorption of as because of competition for adsorption sites a characteristic feature of high groundwater as areas is the large degree of spatial variability in as concentrations in the groundwaters this means that it may be difficult or impossible to predict reliably the likely concentration of as in a particular well from the results of neighbouring wells and means that there is little alternative but to analyse each well arsenic affected aquifers are restricted to certain environments and appear to be the exception rather than the rule in most aquifers the majority of wells are likely to be unaffected even when for example they contain high concentrations of dissolved fe

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

the geology botany and chemistry of selected peat forming environments from temperate and tropical latitudes abstract peat has been studied in several geologic settings 1 glaciated terrain in cold temperate maine and minnesota u s a 2 an island in the atlantic ocean off the coast of maine where sea level is rising 3 the warm temperate u s atlantic and gulf coastal plains where sea level has changed often and 4 the tropical coast of sarawak malaysia and the tropical delta of the batang hari river sumatra indonesia most of these deposits are domed ombrotrophic or partly ombrotrophic bogs in which peat accumulation continued above the surface of the surrounding soil however the bogs of the u s atlantic and gulf coastal plains are comparatively not as domed and many have almost level surfaces in some bogs aquatic or semi aquatic plant materials accumulated replaced water in the depressions and formed a surface on which marsh or swamp vegetation could subsequently live die and accumulate in others the plant materials accumulated initially on level silt or sand surfaces supporting marshes or swamps as the peat dome formed plants growing on it changed from luxuriant ones near the base of the dome where nutrients were brought into the bog by surface and ground water to stunted ones at the top of the dome where the raised bogs are fed by nutrient poor precipitation the physical and chemical changes that take place in the sequence of environments from the pond stage of deposit development through the grassy marsh stage through the forested swamp stage and finally through the heath dome stage can be measured in terms of acidity and ash volatile matter carbon hydrogen nitrogen sulfur and oxygen contents as well as in the kind and distribution of trace elements the organic and inorganic contents of the deposits relate to geomorphology and geomorphology relates to their settings as models of coal formation some domed peat deposits may help in solving problems of distribution and character of ancient coal beds but clearly not all peat deposits are precursors of coal most holocene peat deposits are subject to destruction by erosion fire and decomposition through microbial and chemical oxidation before burial the best environments for coal precursors have biomass accumulation a continuously rising water table within the mass and minimum influx of clay and silt until preservation by burial the most suitable settings for future economic coal deposits are domed bogs that accumulate thick widespread peat having low ash and low sulfur contents the ombrotrophic peat deposits of tropical sarawak and sumatra are thick and extensive contain low ash and low sulfur peat and have high heating values they are considered to be the best tropical coal analogs because of their extent and chances of preservation the base of the peat is below adjacent river levels and chemical and structural conditions are favorable for accumulation

13c 12c ratio double cyclicity in a miocene browncoal isotopic signals and orbital forcing a detailed stable carbon isotopic profile of a late miocene browncoal seam from the lower rhine embayment germany reveals two clear separate cycles of different frequency this is the first instance of this type of isotopic signature being recognized within coals the ratio of the two frequencies suggests this isotopic signal possibly resulted from climatic or vegetational responses to orbital forcing the cyclicity has been enhanced by the application of conventional filtering methods on the data set an analysis of the seam s palynology indicates a correlation between heavier isotopic compositions and the presence of sequoiapollenites polyformosus whose parent plant is believed to have favoured moist climates and higher groundwater tables

rupture process of an extended earthquake sequence teleseismic analysis of the chilean earthquake of march 3 1985 broadband displacement and velocity records of p waves recorded at teleseismic distances are analyzed to determine the static and dynamic source parameters of the chilean earthquake of march 3 1985 ms 7 8 and seven large mb 5 6 aftershocks besides the usual parameters of depth moment and focal mechanism the analysis provides estimates of radiated energy associated stresses and source dimension for seven of the eight modeled earthquakes to insure that the parameters are describing the same physical aspect of the rupture process the parameters for each shock are computed from the time window in which most of the seismic energy is radiated the hypocenters of an additional 149 small foreshocks and aftershocks of 4 5 mb 5 6 are computed with the method of joint hypocenter determination the spatial and temporal variation of source parameters and earthquake locations are used to infer a description of the rupture process before during and after the main shock the main shock and modeled aftershocks occurred as thrust faulting on the interface between the nazca and south american plates a cluster of foreshocks in the 10 days preceding the main shock also involved thrust faulting on the plate interface the main shock itself was a complex rupture consisting of three events the first two events denoted as ms1 and ms2 released minor amounts of energy and they occurred on the periphery of the small zone defined by the foreshocks the major release of energy occurred with the third event denoted by ms which nucleated downdip of ms1 and ms2 within the time window of major energy release rupture extended approximately 90 km to the south from the point at which ms nucleated the size of the early aftershock zone which far exceeds our inferred dimensions for the major shock and the strong frequency dependence of scalar moment imply that substantial slow slip occurred on the plate interface that was not associated with major energy release the dip of the seismically active interface increases landward from about 15 at 20 km depth to about 35 at 40 km depth where the seismogenic interface reaches its maximum observed depth the vast majority of small and moderate aftershocks occurred in the shallower part of the interface as did the foreshocks ms1 and ms2 it appears however that the asperities that control the rupture of the largest earthquakes are the asperities on the deeper interface ms and the largest 1985 aftershock that of april 9 ms 7 2 occurred on the deeper interface the chilean earthquake of july 9 1971 ms 7 5 which occurred just north of the 1985 earthquake also involved main shock rupture on the deeper interface and was followed by aftershocks on the shallower interface asperities on the deeper interface appear on average to be stronger larger and more uniform in size than asperities on the shallow interface a greater average strength for deeper asperities is suggested by the observation that stress drops and apparent stresses of the main shock and the after shock of april 9 ms 7 2 are higher than those of the large shallow aftershocks and is consistent with arguments that the maximum friction on a fault zone should be near the base of the seismogenic zone one deep interface aftershock with low stress drop and apparent stress may have been situated below the point of maximum friction on the interface the inferred larger and more uniform sizes of the deeper asperities are suggested by the higher proportion of large to small shocks on the deeper interface the downdip change in the asperity size distribution may reflect increased friction on the plate interace or the coalescence of small asperities into large asperities with increased subduction the radiated energies of the main shock and large aftershocks that are computed directly from the broad bandwidth data are smaller than those predicted by standard empirical formulas by factors ranging from 4 to 20

paleogeodetic records of seismic and aseismic subduction from central sumatran microatolls indonesia we utilize coral microatolls in western sumatra to document vertical deformation associated with subduction microatolls are very sensitive to fluctuations in sea level and thus act as natural tide gauges they record not only the magnitude of vertical deformation associated with earthquakes paleoseismic data but also continuously track the long term aseismic deformation that occurs during the intervals between earthquakes paleogeodetic data this paper focuses on the twentieth century paleogeodetic history of the equatorial region our coral paleogeodetic record of the 1935 event reveals a classical example of deformations produced by seismic rupture of a shallow subduction interface the site closest to the trench rose 90 cm whereas sites further east sank by as much as 35 cm our model reproduces these paleogeodetic data with a 2 3 m slip event on the interface 88 to 125 km from the trench axis our coral paleogeodetic data reveal slow submergence during the decades before and after the event in the areas of coseismic emergence likewise interseismic emergence occurred before and after the 1935 event in areas of coseismic submergence among the interesting phenomenon we have discovered in the coral record is evidence of a large aseismic slip or silent event in 1962 27 years after the 1935 event paleogeodetic deformation rates in the decades before after and between the 1935 and 1962 events have varied both temporally and spatially during the 25 years following the 1935 event submergence rates were dramatically greater than in prior decades during the past four decades however rates have been lower than in the preceding decades but are still higher than they were prior to 1935 these paleogeodetic records enable us to model the kinematics of the subduction interface throughout the twentieth century

depositional setting for eocene seat earths and related facies of the gippsland basin australia abstract the origin of seat earths i e underclays seat rocks fire clays has been investigated using sedimentological palynological and mineralogical analysis of clastic coal successions from the eocene traralgon formation of the gippsland basin australia the seat earths of the latrobe group are massive a light grey to white colour contain abundant slickensided fracture surfaces and isolated organic matter and mineralogically consist of abundant kaolinite and lesser amounts of 2 m illite from palynological evidence the seat earths have paleoenvironments that grade from a fire prone heath fern meadow marsh i e gleicheniaceae and epacridaceae dominant to fire tolerant shrubs and small trees i e cyatheaceae schizaeaceae and proteaceae dominant that fringe raised peatland rainforests the palynological data also indicate a non marine origin for the kaolinitic mudstones the non marine seat earths were deposited over a foundation of intertidal sediments containing lenticular wavy and flaser bedding tidal rhythmites extensive burrowing and a diverse assemblage of marine influenced dinoflagellates the upward increase in kaolinite slickensides and rootlets within the seat earth indicates this clay was kaolinitized by pedogenic processes i e weathering by organically derived humic fulvic acids prior to and throughout peat formation the presence of well preserved and abundant spore pollen in the kaolinitic mudstones also suggests that the seat earths were deposited in an acidic and relatively reducing setting the stratigraphic transition from tidal siltstone to mudstone seat earth to coal in ascending order is interpreted as a shallowing upwards succession the seat earths of the gippsland basin were therefore deposited as a precursor non marine facies mostly meadow marsh grading into an ombrogenous coal facies thereby explaining the intimate association between coals and seat earths globally

natural organic matter in sedimentary basins and its relation to arsenic in anoxic ground water the example of west bengal and its worldwide implications in order to investigate the mechanism of as release to anoxic ground water in alluvial aquifers the authors sampled ground waters from 3 piezometer nests 79 shallow 80 m wells in an area 750 m by 450 m just north of barasat near kolkata calcutta in southern west bengal high concentrations of as 200 1180 mug l 1 are accompanied by high concentrations of fe 3 13 7 mgl 1 and po4 1 6 5 mg l 1 ground water that is rich in mn 1 5 3 mg l 1 contains 50 mug l 1 of as the composition of shallow ground water varies at the 100 m scale laterally and the metre scale vertically with vertical gradients in as concentration reaching 200 mug l 1 m 1 the as is supplied by reductive dissolution of feooh and release of the sorbed as to solution the process is driven by natural organic matter in peaty strata both within the aquifer sands and in the overlying confining unit in well waters thermotolerant coliforms a proxy for faecal contamination are not present in high numbers 10 cfu 100 ml in 85 of wells showing that faecally derived organic matter does not enter the aquifer does not drive reduction of feooh and so does not release as to ground water arsenic concentrations are high much greater than50 mug l 1 where reduction of feooh is complete and its entire load of sorbed as is released to solution at which point the aquifer sediments become grey in colour as feooh vanishes where reduction is incomplete the sediments are brown in colour and resorption of as to residual feooh keeps as concentrations below 10 mug l 1 in the presence of dissolved fe sorbed as released by reduction of mn oxides does not increase as in ground water because the as resorbs to feooh high concentrations of as are common in alluvial aquifers of the bengal basin arise because himalayan erosion supplies immature sediments with low surface loadings of feooh on mineral grains to a depositional environment that is rich in organic mater so that complete reduction of feooh is common c 2004 published by elsevier ltd

tectonics and history of the andaman sea region abstract the andaman sea is an active backarc basin lying above and behind the sunda subduction zone where convergence between the overriding southeast asian plate and the subducting australian plate is highly oblique the effect of the oblique convergence has been formation of a sliver plate between the subduction zone and a complex right lateral fault system the late paleocene collision of greater india and asia with approximately normal convergence started clockwise rotation and bending of the northern and western sunda arc the initial sliver fault which probably started in the eocene extended through the outer arc ridge offshore from sumatra through the present region of the andaman sea into the sagaing fault with more oblique convergence due to the rotation the rate of strike slip motion increased and a series of extensional basins opened obliquely by the combination of backarc extension and the strike slip motion these basins in sequence are the mergui basin starting at 32 ma the conjoined alcock and sewell rises starting at 23 ma east basin separating the rises from the foot of the continental slope starting at 15 ma and finally at 4 ma the present plate edge was formed alcock and sewell rises were separated by formation of the central andaman basin and the faulting moved onshore from the mentawai fault to the sumatra fault system bisecting sumatra

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

the relationship of the seismic source and subduction zone structure for the 2004 december 26 sumatra andaman earthquake abstract studies of the 2004 december 26 sumatra andaman earthquake indicate that the rupture and subsequent down dip slip of the mw 9 3 event propagated with variable speed as it progressed northwards the transitions between different behaviour for the source correspond to changes in the physical properties of the subducted slab along the sumatra andaman arc revealed by multi wavespeed seismic tomography the transition from rapid slip to dominantly slower slip near 6 5 n and the end of the main zone of tsunamigenic source at 10 n lies in each case just to the south of localised features where changes in the physical properties of the slab are indicated from the ratio of shear wavespeed to bulk sound speed these features are associated mainly with bulk modulus variations the changing morphology of the subduction zone is associated with changes in physical properties that are manifested in the tomographic images and have modified the character of the slip along the 1500 km long arc segment that ruptured during this great earthquake

geochemical and petrographical characteristics of a domed bog nova scotia a modern analogue for temperate coal deposits a freshwater domed bog in nova scotia canada was investigated for its petrographic mineralogical and geochemical characteristics three cores were taken from the lagg zone margin and centre to examine different stages of evolution in a fen to domed bog sequence based on this study a model was developed which shows the relationship between factors controlling peat geochemistry and petrography all of them being dependent on trophic conditions the bog may represent a modern analogue for temperate coal deposits and thus can be used to help understand spatial variability within coal beds rheotrophic conditions in the early stages of mire development result in the formation of high ash highly humified carex dominated peat while the evolution toward ombrotrophic conditions is reflected in a progressive replacement by low ash and well preserved sphagnum dominated peat the associated decrease in ph reflects a decrease of groundwater influence which is also supported by the mineralogical assemblage and petrographic data decrease in reflectance and change in maceral composition except for cl br i and se which are associated with the organic fraction variations in elemental composition can be explained in terms of mineral matter abundance i e decrease upward and with increasing distance from the margin sea spray is the most probable origin for halogen enrichment in the peat

closing the gap between regional and global travel time tomography recent global travel time tomography studies by zhou 1996 and van der hilst et al 1997 have been performed with cell parameterizations of the order of those frequently used in regional tomography studies i e with cell sizes of 1 2 these new global models constitute a considerable improvement over previous results that were obtained with rather coarse parameterizations 5 cells the inferred structures are however of larger scale than is usually obtained in regional models and it is not clear where and if individual cells are actually resolved this study aims at resolving lateral heterogeneity on scales as small as 0 6 in the upper mantle and 1 2 3 in the lower mantle this allows for the adequate mapping of expected small scale structures induced by for example lithosphere subduction deep mantle upwellings and mid ocean ridges there are three major contributions that allow for this advancement first we employ an irregular grid of nonoverlapping cells adapted to the heterogeneous sampling of the earth s mantle by seismic waves spakman and bijwaard 1998 second we exploit the global data set of engdahl et al 1998 which is a reprocessed version of the global data set of the international seismological centre their reprocessing included hypocenter redetermination and phase reidentification finally we combine all data used p pp and pwp phases into nearly 5 million ray bundles with a limited spatial extent such that averaging over large mantle volumes is prevented while the signal to noise ratio is improved in the approximate solution of the huge inverse problem we obtain a variance reduction of 57 1 synthetic sensitivity tests indicate horizontal resolution on the scale of the smallest cells 0 6 or 1 2 in the shallow parts of subduction zones decreasing to approximately 2 3 resolution in well sampled regions in the lower mantle vertical resolution can be worse up to several hundreds of kilometers in subduction zones with rays predominantly pointing along dip important features of the solution are as follows 100 200 km thick high velocity slabs beneath all major subduction zones sometimes flattening in the transition zone and sometimes directly penetrating into the lower mantle large high velocity anomalies in the lower mantle that have been attributed to subduction of the tethys ocean and the farallon plate and low velocity anomalies continuing across the 660 km discontinuity to hotspots at the surface under iceland east africa the canary islands yellowstone and the society islands our findings corroborate that the 660 km boundary may resist but not prevent present day large scale mass transfer from upper to lower mantle or vice versa this observation confirms the results of previous global mantle studies that employed coarser parameterizations

plate boundary deformation associated with the great sumatra andaman earthquake the sumatra andaman earthquake of 26 december 2004 is the first giant earthquake moment magnitude m w 9 0 to have occurred since the advent of modern space based geodesy and broadband seismology it therefore provides an unprecedented opportunity to investigate the characteristics of one of these enormous and rare events here we report estimates of the ground displacement associated with this event using near field global positioning system gps surveys in northwestern sumatra combined with in situ and remote observations of the vertical motion of coral reefs these data show that the earthquake was generated by rupture of the sunda subduction megathrust over a distance of 1 500 kilometres and a width of 150 kilometres megathrust slip exceeded 20 metres offshore northern sumatra mostly at depths shallower than 30 kilometres comparison of the geodetically and seismically inferred slip distribution indicates that 30 per cent additional fault slip accrued in the 1 5 months following the 500 second long seismic rupture both seismic and aseismic slip before our re occupation of gps sites occurred on the shallow portion of the megathrust where the large aceh tsunami originated slip tapers off abruptly along strike beneath simeulue island at the southeastern edge of the rupture where the earthquake nucleated and where an m w 7 2 earthquake occurred in late 2002 this edge also abuts the northern limit of slip in the 28 march 2005 m w 8 7 nias simeulue earthquake

eocene oligocene coals of the gippsland and australo antarctic basins paleoclimatic and paleogeographic context and implications for the earliest cenozoic glaciations abstract australia s gippsland basin contains a semi continuous eocene oligocene 41 5 28 4 ma near coastal coal record that formed adjacent to pacific ocean traralgon and morwell formation brown coals include 4 main seams t2 t1 t0 m2 coal seam palynology records show late middle eocene t2 coals formed under megathermic conditions characterized by high gymnosperm contents late eocene t1 coals formed under mesothermic conditions characterized by reduced gymnosperm contents and earliest indications of palaeoclimate cooling earliest oligocene t0 coal record 33 9 31 5 ma contains high gymnosperm palynology profile very similar to the t2 coals the earliest indication of cooler climes only begins after this coal formed as indicated by low gymnosperm high nothofagus southern beech pollen proportions we suggest in gippsland the earliest evidence for major glacial cooling by inference the oi1 event be placed immediately above the t0 coal seam where early to late oligocene morwell formation sands clays and coals contain low counts of gymnosperms a number of contemporaneous middle to late eocene brown coals occurred in near coastal settings across 1200 km of southern australia palaeogeographically all these coal basins faced the australo antarctic gulf and have a much lower gymnosperm proportion

episodic fire runoff and deposition at the palaeocene eocene boundary qualitative and quantitative coal petrological analyses have been undertaken on the laminated lignite at the base of the cobham lignite bed from scalers hill kent england the maximum negative carbon isotope excursion which marks the beginning of the palaeocene eocene thermal maximum petm occurs near the top of the laminated lignite the lignite contains inertinite a petrographic term used to describe charcoal the laminated lignite has inertinite rich and inertinite poor layers indicative of episodic fires and post fire erosion charcoal clasts are derived from living or recently senesced plants and are dominated by the leaf stalks of herbaceous ferns and wood fragments from flowering plants the charcoal assemblage reflects a low diversity flora possibly adapted to disturbance by fire derived from a source vegetation subjected to seasonal surface wildfires the environmental conditions leading up to and across the onset of the petm are therefore interpreted as incorporating a persistent fire regime with episodic wildfires followed by rainfall and runoff events abundant charcoal indicates near modern oxygen levels whereas the absence of charred peat in this area calls into question previous suggestions that burning of palaeocene peats might have contributed to the short lived negative carbon isotope excursion at the palaeocene eocene boundary

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

factors responsible for high arsenic concentrations in two groundwater catchments in taiwan abstract high as contents in groundwater were found in two neighboring catchments the chianan plain and the southern choushui river alluvial fan in taiwan the groundwater quality the redox potential and the as distribution of the chianan plain were characterized using factor analysis redox zoning and a geochemical program the results were compared with those of the southern choushui river alluvial fan possible as release mechanisms are also elucidated factors 1 and 2 of the groundwater in the chianan plain the salinization factor and the as enrichment factor are similar to those in the southern choushui river alluvial fan however the spatial distribution of reductive tendency in the chianan plain is different to that in the choushui river alluvial fan and yields spatially distinct hydrogeochemical environments in these two neighboring areas the reduction potential in the chianan plain is stronger than that in the choushui river alluvial fan the difference between the reduction potentials in these two vicinal areas influences the concentrations of as in groundwater the reductive dissolution of as rich fe oxyhydroxide is suggested to be the major mechanism for release of as to the groundwater in the chianan plain and the choushui river alluvial fan of taiwan

geochemical characterization of arsenic affected alluvial aquifers of the bengal delta west bengal and bangladesh and chianan plains sw taiwan implications for human health abstract major ion and trace element analyses were performed on groundwater samples collected from the bengal delta chakdaha municipality west bengal and manikgonj town bangladesh and chianan plains sw taiwan to compare geochemical characteristics results showed that concentrations of na k mg cl and so 4 were generally higher in chianan plain cnp groundwaters while high ca was observed in bengal delta plain bdp groundwater measured as concentrations in groundwaters of bdp and cnp showed large variations with mean as concentrations of 221 g l range 1 1 476 g l in chakdaha 60 g l range 0 30 202 g l in manikgonj and 208 g l range 1 3 575 g l in cnp groundwater the fe reduction mechanism was found to be the dominant geochemical process in releasing as from sediment to groundwater in chakdaha west bengal however the mn reduction process was dominant in groundwaters of manikgonj bangladesh in chianan plain groundwater a combination of geochemical processes e g bacterial fe reduction mineral precipitation and dissolution reactions controlled release of as fluorescence spectral patterns of the groundwater showed low relative fluorescence intensity rfi of dissolved humic substances in bdp groundwater mean 63 and 72 qsu chakdaha and manikgonj respectively while high rfi was observed in cnp groundwater mean 393 qsu the ft ir spectra of the extracted humic acid fractions from sediments of chianan plain showed a stronger aliphatic band at 2850 3000 cm 1 and a higher resolved fingerprint area from 1700 to 900 cm 1 compared with bdp sediments the geochemical differences between the study areas may play a crucial role in the clinical manifestation of blackfoot disease observed only in chianan plain sw taiwan

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

on the scalability of hydrogeochemical factors controlling arsenic mobility in three major inland basins of p r china abstract high as groundwater has been widely found in inland basins of p r china which has posed a serious health risk to the local residents although these inland basins experience the same arid to semiarid climate and are filled with quaternary sediments as concentrations show big variations three inlands basins have been investigated to characterize hydraulic conductivities and geochemistry of the groundwater and sediments and evaluate their controls on dissolved as concentrations dissolved as concentrations ranged between

some observations regarding the potential effects of doming of tropical peat deposits on the composition of coal beds abstract several important concepts relative to the origin of coal beds can be gleaned from studies of modern domed and planar peat deposits in tropical subtropical settings these are 1 laterally some portions of a single continuous peat deposit may be domed and some portions may be planar 2 domed deposits are most often found to have begun as planar deposits 3 domed formed peat facies may be overridden by planar formed peat facies due to such factors as sea level rise and or increased rate of local and basinal subsidence 4 domed peat facies tend to have less mineral matter and contain fewer inorganic splits than planar facies 5 sulfur intrusion from marine waters can be retarded by doming allowing low sulfur peats to form relatively near to the coastline 6 marine transgression can cause high sulfur marine influenced planar peat facies to override freshwater domed or planar facies resulting in enrichment of the upper parts of these underlying facies in sulfur and ash 7 dome formed peat facies tend to be thicker and more uniform in composition than planar formed facies with dome formed peat facies having the potential to produce the more uniform bright coal types clarains and vitrains and planar formed peat facies often producing duller coal types and or alternating durainic inertinite rich and vitrainic wood derived bands 8 actively developing peat domes in wet settings often exhibit no appreciable increase in inertinitic material toward their tops although the tops of either domed or planar peat deposits can be enriched in inertinitic material if the water table is lowered by either local or regional changes in hydrology or climate

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

sulphur and carbon isotopic composition of power supply coals in the pannonian basin hungary abstract the present work is an attempt to establish the stable isotope database for mesozoic to tertiary coals from the pannonian basin hungary maceral composition proximate analysis sulphur form sulphur isotopes organic and pyritic and carbon isotopes were determined this database supports the assessment of the environmental risks associated with energy generation the characterization of the formation and the distribution of sulphur in the coals used the maceral composition the sulphur composition the c s isotopic signatures and some of the geological evidences published earlier show that the majority of these coals were deposited in freshwater and brackish water environments despite the relatively high average sulphur content however the upper cretaceous eocene and lower miocene formations also contain coal seams of marine origin as indicated by their maceral composition and sulphur and carbon chemistry the majority of the sulphur in these coals occurs in the organic form all studied sulphur phases are relatively rich in 34s isotopes 34sorganic 12 74 34spyrite 10 06 on average this indicates that marine bacterial sulphate reduction played a minor role in their formation in the sense that isotopic fractionation was limited it seems that the interstitial spaces of the peat closed rapidly during early diagenesis due to a regime of high depositional rate leading to a relative enrichment of the heavy sulphur isotopes

stable isotopic and elemental characteristics of pale and dark layers in a late pliocene lignite deposit basin in yunnan province southwestern china implications for paleoenvironmental changes abstract the carbon and nitrogen stable isotopic compositions and elemental characteristics of pliocene pale and dark lignites in the jinsuo basin yunnan province southwestern china were investigated these data were used to develop paleoenvironmental models and to discuss possible geological driving forces for the formation of pale and dark layers the 13c values of fossil wood av 24 79 and fusain samples av 24 19 are generally higher than the values obtained from bulk pale av 27 01 and dark av 26 38 lignite samples in contrast the 15n values of fossil wood av 0 63 and fusain samples av 1 29 are lower than the average values of bulk pale lignites av 2 17 and dark lignites av 1 79 the difference in the carbon isotopic values between pale and dark lignites can be explained by the very high amount of liptinite and strong degradation of woody material by bacterial activity in pale lignites which resulted in depletion of 13c in pale lignites and the wet humid depositional conditions contributed to the relatively heavy stable carbon isotope compositions of dark layers the higher 13c values in the fossil wood and fusain samples can be explained by the general enrichment of 13c in woody material compared to leaves the weakly negative correlation between the 15n and 13c values indicates that besides bacterial degradation the liptinite content could also influence the carbon and nitrogen compositions of lignites the influence of the original plant community gymnosperms angiosperms on the carbon and nitrogen isotopic compositions of bulk lignites is insignificant in the jinsuo basin the paleoenvironmental model suggests deposition of pale layers under relatively dry cold conditions supporting the expansion of gymnosperms such as pinus yunnanensis the slight stepwise uplift of the tibetan plateau and the approximate co occurrence of the more intense asian monsoon might have supported short periods of a locally dry cold climate resulting in the lowering of water table which was favorable for the formation of pale layers the low 13c values in pale layers further support this the relatively high sio2 al2o3 ratios higher values of the average detrital authigenic index and high levels of tio2 and zr in pale layers suggest an increased detrital input relative to dark layers the dark layers however formed in a tropical subtropical warm humid climate that favored angiosperm dominance of the vegetation the long term geologically stable conditions together with the regionally warm humid climate resulted in a rise in the water table in the basin which led to the formation of dark layers until the subsequent slight uplift of the tibetan plateau this conclusion is also supported by the high 13c values in dark layers and the thickness differences between pale thin and dark thick layers and the changes in major elements and minerals changes between the two types of layer

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

arsenic in groundwater testing pollution mechanisms for sedimentary aquifers in bangladesh in the deltaic plain of the ganges meghna brahmaputra rivers arsenic concentrations in groundwater commonly exceed regulatory limits 50 m gl 21 because feooh is microbially reduced and releases its sorbed load of arsenic to groundwater neither pyrite oxidation nor competitive exchange with fertilizer phosphate contribute to arsenic pollution the most intense reduction and so severest pollution is driven by microbial degradation of buried deposits of peat concentrations of ammonium up to 23 mg l 21 come from microbial fermentation of buried peat and organic waste in latrines concentrations of phosphorus of up to 5 mg l 21 come from the release of sorbed phosphorus when feooh is reductively dissolved and from degradation of peat and organic waste from latrines calcium and barium in groundwater come from dissolution of detrital and possibly pedogenic carbonate while magnesium is supplied by both carbonate dissolution and weathering of mica the 87 sr 86 sr values of dissolved strontium define a two component mixing trend between monsoonal rainfall 0 711 6 0 001 and detrital carbonate 0 735

arsenic contamination in surface drainage and groundwater in part of the southeast asian tin belt nakhon si thammarat province southern thailand the occurrence of human health problems resulting from arsenic contamination of domestic water supplies in ron phibun district nakhon si thammarat province southern thailand was first recognized in 1987 the area has an extensive history of bedrock and alluvial mining the waste from which is typically rich in arsenopyrite and related alteration products in 1994 a collaborative study was instigated involving thai and british government authorities to establish the distribution and geochemical form of as in surface drainage and aquifer systems in the affected area the probable sources of as contamination and the potential for problem alleviation hydrochemical analyses of surface and groundwaters have confirmed the presence of dissolved as at concentrations exceeding who potable water guidelines by up to a factor of 500 contamination of the shallow alluvial aquifer system is systematically more severe than the underlying carbonate hosted aquifer deep boreholes may therefore provide the best available potable water source for the local population the presence of up to 39 of total as as arsenite h3aso3 within the carbonate aquifer may however constitute a hidden toxicological risk not evident in the shallow groundwater in which arsenate species account for 95 of total as mineralogical investigations of as rich tailings and flotation wastes were undertaken to evaluate their likely impact on water quality the results indicate that although some flotation wastes contain up to 30 as the rate of leaching is extremely low consequently the as loading of drainage emanating from such waste is below the subregional average analyses of the silty alluvium that covers much of the central sector of the study area have highlighted as concentrations of up to 5000 mg kg 1 probably carried by disseminated arsenopyrite following sulfide dissolution the mobility of as in this material may be high with resultant contamination of shallow groundwater due to the low fe content of the soil on the basis of the data acquired a range of pollution mitigation schemes are currently under investigation including fe supplementation of alluvium and microbial degradation of disseminated arsenopyrite

mobility of arsenic in a bangladesh aquifer inferences from geochemical profiles leaching data and mineralogical characterization aquifer geochemistry was characterized at a field site in the munshiganj district of bangladesh where the groundwater is severely contaminated by as vertical profiles of aqueous and solid phase parameters were measured in a sandy deep aquifer depth 150 m below a thick confining clay 119 to 150 m a sandy upper aquifer 3 5 to 119 m above this confining layer and a surficial clay layer 3 5 m in the deep aquifer and near the top of the upper aquifer aqueous as levels are low 10 g l but aqueous as approaches a maximum of 640 g l at a depth of 30 to 40 m and falls to 58 g l near the base 107 m of the upper aquifer in contrast solid phase as concentrations are uniformly low rarely exceeding 2 g g in the two sandy aquifers and never exceeding 10 g g in the clay layers solid phase as is also similarly distributed among a variety of reservoirs in the deep and upper aquifer including adsorbed as as coprecipitated in solids leachable by mild acids and reductants and as incorporated in silicates and other more recalcitrant phases one notable difference among depths is that sorbed as loads considered with respect to solid phase fe extractable with 1 n hcl 0 2 m oxalic acid and a 0 5 m ti iii citrate edta solution appear to be at capacity at depths where aqueous as is highest this suggests that sorption limitations may in part explain the aqueous as depth profile at this site competition for sorption sites by silicate phosphate and carbonate oxyanions appear to sustain elevated aqueous as levels in the upper aquifer furthermore geochemical profiles are consistent with the hypothesis that past or ongoing reductive dissolution of fe iii oxyhydroxides acts synergistically with competitive sorption to maintain elevated dissolved as levels in the upper aquifer microprobe data indicate substantial spatial comapping between as and fe in both the upper and deep aquifer sediments and microscopic observations reveal ubiquitous fe coatings on most solid phases including quartz feldspars and aluminosilicates extraction results and xrd analysis of density magnetic separates suggest that these coatings may comprise predominantly fe ii and mixed valence fe solids although the presence of fe iii oxyhydroxides can not be ruled out these data suggest as release may continue to be linked to dissolution processes targeting fe or fe rich phases in these aquifers copyright 2004 elsevier ltd

teleseismic relocation and assessment of seismicity 1918 2005 in the region of the 2004 mw 9 0 sumatra andaman and 2005 mw 8 6 nias island great earthquakes the m w 9 0 2004 sumatra andaman islands and m w 8 6 nias island great earthquake sequences have generated over 5000 catalog reported earthquakes along 1700 km of the sumatra andaman and western sunda regions studies of prior regional seismicity have been limited to global catalog locations that often have poorly constrained epicenters and depths approximately 3650 teleseismically well recorded earthquakes occurring in this region during the period 1918 2005 are relocated with special attention to focal depth reduced uncertainties of epicenters and depths in the region on the order of 15 and 10 km respectively foster interpretation of focal mechanism data and provide additional details about the subducting indian and australian plates the revised earthquake dataset reveals a sharp delineation between aftershocks of the 2004 and 2005 earthquakes near simeulue island and a steepening in slab dip from south to north the downdip width of the aftershock zone of the 2004 m w 9 0 earthquake varies from 200 km at its northern end to 275 km at its southern end and events located between 35 and 70 km focal depth occur more frequently in the southernmost section of this aftershock zone outer rise and near trench normal and strike slip faulting earthquakes also increase in frequency following the 2004 and 2005 earthquakes earthquake swarms triggered along the andaman backarc spreading center both north of sumatra and near siberut island 100 km south of the nias island aftershock sequence illustrate the complex and variable nature of seismicity following these great earthquakes

effect of indigenous bacteria on geochemical behavior of arsenic in aquifer sediments from the hetao basin inner mongolia evidence from sediment incubations abstract incubation studies were carried out using 5 freshly collected sediments from shallow aquifers of the hetao basin inner mongolia the aquifer sediments covering a range of redox conditions as indicated by their deep grey to yellow color were mixed with degassed artificial as solution or degassed deionized water at a ratio of solid to water of about 1 10 wt wt suspensions which were either amended with glucose or autoclaved were incubated in parallel with unamended suspensions five microcosm cultures of unamended sediments gradually release the equivalent of 0 03 0 30 g g as to the dissolved phase the addition of glucose as a potential electron donor results in a marked stimulation in the mobilization of as 0 71 3 81 g g in the amended incubations for all sediments the quantity of as released accounts for 60 70 of as bound to fe mn oxides in the original sediments the microbially mediated mobilization of as with the organic nutrient as an electron donor is strongly associated with the as bound to fe mn oxides as well as the exchangeable as during the incubations amended with glucose 2 4 of the sediment fe is released the results suggest that the introduction of labile dissolved organic c into the yellowish sediment aquifers with as free groundwater would reduce a significant proportion of the fe iii oxyhydroxides mediated by anaerobic bacteria respiration and increase groundwater as concentrations

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

environmental history of the german lower rhine embayment during the middle miocene as reflected by carbon isotopes in brown coal stable carbon isotope investigations have been carried out on miocene brown coal from the garzweiler seam of the german lower rhine embayment material studied included fossil wood from seven different taxa and brown coal matrix isotope results from macrofossil analysis show variations of more than 6 within individual samples and reveal a general isotopic difference between angiosperm and gymnosperm wood specimens according to mean carbon isotope values found for gymnosperms angiosperms and brown coal matrix 23 3 26 0 and 25 8 the peat forming vegetation of the garzweiler seam was dominated by angiosperm taxa results from brown coal matrix establish a continuous high resolution depth profile of carbon isotope variations during the late middle miocene they show a significant and characteristic isotope pattern with distinct medium and short term cycles high frequency variations in the two main units of garzweiler seam locally split into three units the medium term 13c variations are most likely caused by varying proportions of gymnosperms within the peat forming vegetation while high frequency oscillations seem to be a direct signal of environmental changes a long term decline of carbon isotope values observed within the complete garzweiler seam from base to top is presumably due to a cooling trend in the miocene

source area and rupture parameters of the 31 december 1881 mw 7 9 car nicobar earthquake estimated from tsunamis recorded in the bay of bengal 1 on the morning of 31 december 1881 a submarine earthquake beneath the andaman islands generated a tsunami with a maximum crest height of 0 8 m that was recorded by eight tide gauges surrounding the bay of bengal since the earthquake occurred 8 years before the construction of the world s first teleseismic recording seismometer little has been known about its rupture parameters or location waveform and amplitude modeling of the tsunami indicate that it was generated by a mw 7 9 0 1 rupture on the india andaman plate boundary resulting in 10 60 cm of uplift of the island of car nicobar the rupture consisted of two segments the northern 40 km long segment is separated from the southern 150 km long segment by a 100 km region corresponding to the westward projection of the west andaman spreading center the main rupture occurred between 8 5 n and 10 n with a total area of 150 km 60 km dipping 20 e with a mean slip of 2 7 m the recurrence time for 1881 type events is estimated to be 114 200 years on the basis of inferred gps convergence rates and inferred plate closure vectors although slip partitioning in the region may extend this estimate by as much as 30

punctuated aggradational cycles a general hypothesis of episodic stratigraphic accumulation according to the hypothesis of punctuated aggradational cycles presented here the stratigraphic record consists of small scale 1 5 m thick shallowing upward cycles pacs separated by surfaces marked by abrupt change to deeper facies this motif pervasive in time and environment is produced by relatively long periods tens of thousands of years of base level stability punctuated by geologically instantaneous relative base level rises of at least basin wide extent as basin wide lithologic time stratigraphic units pacs are fundamental to all aspects of stratigraphic analysis including correlation paleoenvironmental interpretation and paleogeographic reconstruction of several possible allogenic mechanisms for a pervasively cyclic stratigraphic record glacial eustasy driven by orbital perturbations is preferred the pac hypothesis is presented as a comprehensive model to be tested and modified by examination of the stratigraphic record from an episodic perspective

models for generation of carbonate cycles computer modeling provides a quantitative approach to a better understanding of actual carbonate cyclic sequences to model carbonate cycles the authors can use water depth dependent sedimentation rate for each facies an initial lag time linear subsidence tidal range and period and amplitude of sea level oscillation about a horizontal datum tidal flat capped cycles up to a few meters thick result from low amplitude sea level oscillation of a few meters and short lag times nonerosive caps reflect sea level lowering being balanced by subsidence and basinward migration of the shoreline not exceeding tidal flat progradation rate when higher amplitude sea level oscillations occur the tidal flats are abandoned on the inner shelf during sea level fall because seaward movement of the strandline outpaces progradation rate of flats increased amplitude also results in sea level falling faster than flats can subside so that disconformities with thick vadose profiles develop high amplitude 100 m or more oscillations result in incipient drowning of platforms and juxtaposition of deep water facies against shallow water facies within cycles sea level falls before the platform can build to the sea level highstand and the shoreline migrates much more rapidly than tidal flats can prograde thus cycles are disconformity bounded and lack tidal flat caps 10 references

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