the carbonate factory revisited a reexamination of sediment production functions used to model deposition on carbonate platforms there are two widely used models of sediment production on carbonate shelves 1 production varying with depth and 2 production as a function of depth and distance from the platform margin here we recalculate carbonate production on great bahama bank west and northwest of andros island using broecker and takahashi s 1966 pioneering geochemical study in the calculations residence time and depth are used to calculate yearly carbonate production based on equilibrium thermodynamics of caco3 loss from water over the banks whereas broecker and takahashi assumed a uniform depth of 4 5 m in their work here we use realistic depths and residence times interpolated over the bank our results suggest that sediment production is on the order of 4 5 kg m2 y on the bank margins and that production rapidly drops off into the platform approaching zero in the shallowest innermost parts of the platform thus for a large platform such as great bahama bank with long residence times the shallowest areas of the platform may become sinks not sources of sediment

high 3he emanations from the source regions of recent large earthquakes central japan 1 recently two shallow mw 6 6 inland earthquakes the 2004 mid niigata prefecture earthquake and the 2007 niigataken chuetsu oki earthquake occurred in the niigata sedimentary basin near the boundary between the eurasian and the north american plates in order to elucidate the geographic distribution of the 3he 4he ratios in and around the seismic source regions new helium isotope data from hot spring gases and water samples from much denser sampling than in previous studies were determined although temporal changes in the 3he 4he ratios obtained from each well were unknown before and after the earthquakes higher 3he 4he ratios were observed in the earthquake source regions compared to other regions geochemical evidence for the presence of hot spring gases and natural gases with anomalously high 3he 4he ratios 3 8 ra indicates infiltration of mantle fluids derived from the subcrustal lithosphere a plausible source of mantle helium can be attributed to upward mobilization of aqueous fluids generated by dehydration of the subducting pacific plate slab resulting in the acquisition of primordial helium from a mantle wedge as the fluids into the crust in addition aqueous fluids may raise the earth s surface along permeable conduits leading to the reactivation of high angle inverted normal faults and the triggering of recent earthquakes

coal characteristics elemental composition and modes of occurrence of some elements in the isaalan coal balikesir nw turkey abstract this study uses coal petrography micro ftir mineralogical and geochemical analyses to determine the coal characteristics and controlling factors of elemental enrichments in the isaalan coal nw turkey the obtained data show that this subbituminous coal has a relatively low ash yield avg 19 high hydrogen content avg 5 4 and total s content avg 2 4 on an air dry basis the maceral composition along with micro ftir data on ulminite suggests that lignin and resin rich vegetation was predominant the coal facies data imply the precursor peat was accumulating under mesotrophic anoxic conditions where water level was high and fluctuating the mineralogical composition of the bulk coal samples is composed mainly of quartz pyrite and clay minerals and lesser amounts of feldspars and carbonates the statistical analysis of the bulk compositional data shows the major elements including al fe k na mg p and the vast majority of trace elements have inorganic affinity whereas b presumably has organic affinity the trace element concentrations are variable and especially as and elements including b ba cr cs ni sb and v are enriched compared to most world coals the enrichments and distributions of cr cs ni and v were controlled by clastic inputs into a palaeomire whereas as enrichments were controlled mainly by epigenetic and to a lesser extent syngenetic factors introduced so42 and as rich surface and groundwater from the basin margin area along with anoxic conditions in the palaeomire resulted in syngenetic formation of as bearing pyrite the circulating intra seam solutions later liberated as from syngenetically formed pyrite which resulted in as and ni rich overgrowths around framboidal and massive pyrite crystals these solutions could also easily mobilize b that was absorbed by organic matter therefore b enrichment appears to be related to epigenetic factors tectonic activities during coalification allowed hydrothermal solutions from neighbouring epithermal mineralisation to penetrate and circulate along with underground waters that leached overlying volcanoclastic volcanic strata and supplied a number of elements to the studied coal thus infilling as bearing pyrite and silica were formed mainly during coalification all these results suggest that as enrichment in the study area is more likely a combination of epigenetic factors and syngenetic detrital rather than volcanogenic contributions as suggested earlier for some other turkish coal deposits

geochemistry mineralogy and technological properties of coals from rio maior portugal and penarroya spain basins abstract this study focuses on the geochemistry and mineralogy of pliocene lignites from the rio maior basin portugal and of late westphalian bituminous and anthracite coals from the penarroya basin spain major mineral phases present in the rio maior lignites are quartz and clay minerals with minor amounts of other detrital minerals depending on the sedimentary environment and the source of the detrital input the concentration of rb cs sc v u and gd in lignites is higher than the maximum value established for the usual worldwide concentration range for coal geochemical affinity study for major and trace elements in rio maior established three major associations i aluminium silicate affinity fe mg na k li rb sc zr v cr co ni se pb sb gd and tb ii the sulphur affinity mo and as and iii organic affinity sr ca mn ba and u ce and cs affinities could not be explained with the available data in the penarroya bituminous coals the main mineral phases identified were quartz and clay minerals kaolinite and illite minor traces of anatase and epigenetic carbonates elements with inorganic affinity fe mg na k ti li rb cs ba sc zr v cr co ni pb u se ce gd tb cu have a high to medium aluminium silicate affinity anomalous concentrations of li rb cs sc v and cr could be related to the input of detrital minerals from the precambrian and lower palaeozoic rocks in the northeastern part of penarroya basin anthracites from the penarroya basin have the following mineral phases calcium iron and magnesium carbonates clay minerals and quartz as well as traces of apatite and of pyrite carbonates and some kaolinite are clearly epigenetic as a consequence of fluid circulation related to magmatic activity two main geochemical associations were found i aluminium silicate affinity na k ti rb cs ba sc cr mo ni cd as sb se ce gd tb cu and ii carbonate affinity ca mg fe v mn sr an anomalous amount of mn and v is considered to be related with the circulation of magmatic fluids the geochemical and mineralogical variations observed were primarily related to coal rank in the penarroya basin whilst paleoenvironmental depositional conditions were more important in the rio maior basin the chemical composition of the high temperature ashes is related to the trend followed by the ash fusion temperatures and to the predictive indices associated with slagging and fouling propensities these indices indicate low to medium slagging and fouling propensities for all the coals studied

the origins of shallow water carbonate lithofacies thickness distributions one dimensional forward modelling of relative sea level and production rate control the observation that shallow marine carbonate strata often have exponential lithofacies thickness distributions is one of the most fundamental results in carbonate stratigraphy in recent years because it is an observation that can be tested for its repeatability in various outcrop and subsurface examples and also because it raises the question of what sedimentary processes and climatic and oceanographic settings might lead to formation of a particular lithofacies thickness distribution this observation in turn links to the significant issue of how carbonate strata record climatic and oceanographic change through geological time this study applies a simple one dimensional numerical stratigraphic forward model of carbonate platform strata dougal to study how relative sea level oscillations could control lithofacies distribution dougal records platform top carbonate accumulation influenced by water depth dependent sediment production in euphotic oligophotic and aphotic production profiles with a lag depth controlling onset of production results from five single model runs highlight the issue of non stationary behaviour where statistical properties of the strata change with elevation up the section and show that exponential lithofacies thickness distributions can be generated from an entirely deterministic model results of multiple model runs 27 200 in total spanning a range of production and accommodation creation rates demonstrate that the three main controls on carbonate lithofacies distribution in this one dimensional model are i complex variations in the rate of creation of accommodation here due to high frequency glacio eustatic oscillations ii rate of sediment production dominated in these model runs by euphotic production rates and iii operation of autocyclic oscillations in deposition driven by a lag depth effect and formed during certain high frequency rising limbs on the glacio eustatic curve in these multiple model runs only ca 13 of the total runs created exponential distributions compared with 28 in the documented outcrop examples suggesting that other processes not included in this model play an important role more work is required to determine what these processes might be obvious candidates would be the various sedimentary processes that occur in three dimensions on platform tops such as sediment transport and variations in rate and type of sediment production related to biological variability and other process that occur in other different depositional settings for example sediment transport on slopes

co2 degassing over seismic areas the role of mechanochemical production at the study case of central apennines field observations coupled with experimental results show that co2 can be produced by mechanical energy applied to carbonate rocks becoming an unexpected additional gas source besides that degassed from the mantle or produced by thermometamorphism the evidence that a large amount of carbon dioxide associated with radiogenic type helium r ra as low as 0 01 0 08 is released through continental areas denotes the absence of a contribution from the mantle or from mantle derived fluids data collected during the seismic crisis which struck the central apennines in 1997 98 have shown an enhanced co2 flux not associated with the presence of mantle or thermometamorphic derived fluids on the other hand new experimental results highlight the possibility of producing co2 by mechanical energy that acts on the calcite crystalline lattice while the co2 released over the geothermal areas e g larderello geothermal field is obviously derived by mantlederived activities this is not the case of the huge amount of co2 released over the seismically active areas where the presence mantle derived products is ruled out we propose that mechanical energy e g released during seismic events microseismicity or creeping processes is a possible additional energy source able to produce co2 and thus could explain the presence of co2 degassing over tectonic areas where the influence of the mantle is low

methane flux and origin in the othrys ophiolite hyperalkaline springs greece abstract the occurrence and origin of methane ch4 generated by serpentinization of ultramafic rocks is of current timely interest in planetary geology astrobiology and energy resource exploration as it may contribute in particular to decipher the source of methane on mars the origin of life and the potential of abiotic hydrocarbon synthesis methane of dominant abiotic origin in serpentinized peridotites on continents ophiolites or igneous intrusions has been documented so far with complete carbon and hydrogen isotope composition in six countries in the philippines turkey oman new zealand japan and italy we report the discovery of two new sites in greece at archani and ekkara located in the othrys ophiolite massif portable sensors based on fourier transform infrared spectrometry ftir and tunable diode laser absorption spectroscopy tdlas allowed to realize that out of 21 ophiolitic springs methane is released only by four hyperalkaline ph from 10 7 to 11 3 and calcium hydroxide ca oh type waters all other 17 springs with ph

rate of strike slip motion on the amanos fault karasu valley southern turkey constrained by k ar dating and geochemical analysis of quaternary basalts the left lateral amanos fault follows a 200 km long and up to 2 km high escarpment that bounds the eastern margin of the amanos mountain range and the western margin of the karasu valley in southern turkey just east of the northeastern corner of the mediterranean sea regional kinematic models have reached diverse conclusions as to the role of this fault in accommodating relative motion between either the african and arabian turkish and african or turkish and arabian plates local studies have tried to estimate its slip rate by k ar dating quaternary basalts that erupted within the amanos mountains flowed across it into the karasu valley and have since become offset however these studies have yielded a wide range of results ranging from 0 3 to 15 mm a 1 which do not allow the overall role and significance of this fault in accommodating crustal deformation to be determined we have used the cassignol k ar method to date nine quaternary basalt samples from the vicinity of the southern part of the amanos fault these basalts exhibit a diverse chemistry which we interpret as a consequence varying degrees of partial melting of their source combined with variable crustal contamination this dating allows us to constrain the quaternary slip rate on the amanos fault to 1 0 to 1 6 mm a 1 the dramatic discrepancies between past estimates of this slip rate are partly due to technical difficulties in k ar dating of young basalts by isotope dilution in addition previous studies at the key locality of hacilar have unwittingly dated different chemically distinct flow units of different ages that are juxtaposed this low slip rate indicates that at present the amanos fault takes up a small proportion of the relative motion between the african and arabian plates which is transferred southward to the dead sea fault zone it also provides strong evidence against the long standing view that its slip continues offshore to the southwest along a hypothetical left lateral fault zone located south of cyprus

the interaction of acid mine drainage with a carbonate terrane evidence from the obey river north central tennessee abstract the production of acidic drainage from active or abandoned coal mines is controlled by a complex series of reactions triggered by the oxidation of sulphide minerals limestone is frequently used as a neutralizing agent neutralization occurs both through dissolution of the limestone and exsolution of carbon dioxide from the water demonstration of these processes in a natural system is provided by the east fork of the obey river where acidic mine waters travel through conduits in limestone bedrock for several kilometers application of discharge concentration relationships allows tracking of the evolution of these waters within the karst aquifer several trends are evident virtually all of the iron in the acid mine drainage is precipitated along the flow path within the limestone the h released during this reaction together with the h generated by pyrite oxidation is largely neutralized by both exsolution of co 2 and dissolution of calcite dolomite in the carbonate bedrock releasing calcium and magnesium nevertheless the ph is still sufficiently low that all bicarbonate is converted to carbonic acid leaching of clay minerals by the acid waters releases small amounts of al and si the species cl f and no 3 are more or less inert the sulphate concentration substantially increases during evolution of the acid drainage this seems to be related to an input of sulphate enriched waters that have dissolved gypsum anhydrite as they follow deep flow paths within the limestone calculations of the relative proportions of h removed by reaction with calcite dolomite and co 2 degassing show that the latter is important in acidic waters that have reacted significantly with limestone and can readily lose co 2 to the atmosphere these results indicate that acid neutralization through carbonic acid dissociation in addition to neutralization through dissolution of carbonates is a useful method for the commercial a batement of acid mine drainage

geoecology of ecosystem recovery at an inactive coal mine site new zealand ecological restoration of the wangaloa coal mine in southern new zealand is hindered by a range of geoecological factors the site has some substrate acidification down to ph 1 and acid rock drainage with discharge waters initially down to ph 4 although this has since risen to ca ph 6 surface and ground waters develop elevated sulfate up to 700 mg kg during oxidation of pyrite in coal and quartz in waste rock coal has elevated boron content up to 450 mg kg and surface waters on coal rich waste rock have up to 6 mg l dissolved boron evaporation causes formation of salt encrustations dominated by gypsum with minor boron salts boron is bioavailable and may be at toxic levels 200 mg kg in some plants quartz rich waste rock is readily eroded and develops a cm scale low nutrient quartz pebble armouring layer with low water retention properties all waste rocks including loess siltstone have low nutrient contents and low moisture retention properties that are barely sufficient for plant establishment native plants introduced to the site during rehabilitation have grown on loess substrate up to fivefold increase in height over 3 years with poor or no growth on coal rich and quartz rich substrates in contrast natural colonisation of manuka leptospermum scoparium has been most effective at revegetation on even the most hostile substrates this natural revegetation has been facilitated by islands of manuka established accidentally during 60 years of mining history manuka from local genetic stock is most viable for this revegetation and introduced manuka seedlings have had a 70 mortality rate natural plant colonisation is the key step in overall ecosystem recovery and invertebrates rapidly colonise beneath new shrubs irrespective of the nature of the substrate from vegetation islands that have high invertebrate numbers and species richness

field evidences from northern dead sea fault zone south turkey new findings for the initiation age and slip rate abstract the left lateral strike slip dead sea fault zone dsfz extends from the red sea in the south to the east anatolian fault zone eafz in the north this study examines the northern part of the dsfz around amik basin and presents surface and subsurface geological evidence for the quaternary activity and initiation age of the northernmost dsfz the dsfz extends n s in the south of the amik basin where clear geological and morphological evidence exists for faulting geological observations around amik basin analyses of borehole data and electrical resistivity profiles within the amik basin indicate that the activity of the northern dsfz started after pliocene in the amik basin subsurface data in the basin suggest that the dsfz offsets a pre quaternary basin sinistrally by about 7 9 km the offset pre quaternary basin suggests at least 4 94 0 13 mm year slip rate for the northern part of the dsfz the karasu fault zone kfz extends in an en echelon pattern along the western margin of the karasu valley and it transfers the significant amount of slip from dsfz to the eafz

kinematics of the amanos fault southern turkey from ar ar dating of offset pleistocene basalt flows transpression between the african and arabian plates

preservation of forcing signals in shallow water carbonate sediments abstract no consensus has been reached on whether the metre scale cycles that commonly occur in peritidal carbonates are predominately a product of external relative sea level variations allocycles or an intrinsic property of carbonate production generated via the interaction of non linear processes autocycles for any forcing signal such as eustatic sea level change to be detectable in stratigraphy its effects must be preserved here a deterministic three dimensional geological process model is used to explore how such cycles are preserved in the geological record in the presence of autocyclic processes each simulation produced cycle thickness distributions that are statistically indistinguishable from a theoretical poisson process regardless of whether auto or allo cycles dominated spectral analysis of depositional time series constructed from idealised geological sections showed that all detectable signals occurred within the milankovitch forcing frequency bands even when no milankovitch forcing was present thus it is deduced that from any geological section alone external forcing signals are detectable but are not distinguishable from autocyclically produced signals interestingly there is no correlation between the percentage of sediment preserved and the accuracy with which signals are detectable in the preserved sediment in some model realisations even with preservation as low as 40 the correct forcing signal can be detected accurately while conversely sections with preservation as high as 90 can have poor signal preservation the reverse can also be true in other models it is therefore concluded that distinguishing allocyclic and autocyclic forcing in shallow marine or peritidal carbonate successions is likely to be extremely difficult except in cases of extraordinary sedimentary preservation and dating accuracy

the east anatolian fault an oblique collisional belt abstract the tectonic setting for the area around the arabia africa anatolia triple junction is described from combined landsat spot satellite image analysis and field observations since the late miocene the motion along the east anatolian fault generated major structures corresponding to shortening with a sinistral slip component the 150 km wide area of the triple junction is highly deformed by folding and thrusting distributed mainly on the border of the anatolian block in addition kinematic reconstructions confirm that the arabia anatolia relative motion is both sinistral and convergent the sinistral strike slip faults of the east anatolian fault zone are of second order and local consequences of the n s arabia anatolia collision

a geochemical traverse along the sperchios basin e evoikos gulf graben central greece origin and evolution of the emitted fluids the studied area is a 130 km long fast spreading graben in central greece its complex geodynamical setting includes both the presence of a subduction slab at depth responsible for the recent quaternary volcanic activity in the area and the western termination of a tectonic lineament of regional importance the north anatolian fault a high geothermal gradient is made evident by the presence of many thermal springs with temperatures from 19 to 82 c that discharge along the normal faults bordering the graben in the period 2004 2012 58 gas and 69 water samples were collected and their chemical and isotopic analysis revealed a wide range of compositions two main groups of thermal waters can be distinguished on the basis of their chemical composition the first represented by dilute waters e c 0 6 ms cm of the westernmost sites is characterised by the presence of ch4 rich and mixed n2 ch4 gases the second displays higher salinities e c from 12 to 56 ms cm due to mixing with a modified marine component reservoir temperatures of 150 160 c were estimated with cationic geothermometers at the easternmost sites along the graben from west to east the gas composition changes from ch4 to co2 dominated through mixed n2 ch4 and n2 co2 compositions while at the same time the he isotopic composition goes from typical crustal values 0 1 r ra up to 0 87 r ra showing in the easternmost sites a small 3 11 but significant mantle input the 13c values of the co2 rich samples suggest a mixed origin mantle and marine carbonates

geochemical changes during neutralisation of acid mine drainage in a dynamic mountain stream new zealand abstract the mangatini stream drains a coal mining area in the mountains of northwestern south island of new zealand abundant rainfall on pyritic rocks yields acid mine drainage amd to the stream which flows through a steep gorge at discharges that rapidly increase from 100 m3 s during frequent rain events the amd is treated with finely ground limestone which is discharged as a slurry at a point in the middle of the gorge the limestone slurry mixes and reacts with the amd during flow 4 km downstream over 12 h neutralisation reactions increase stream ph from near 3 untreated mangatini stream water impacted by amd to 5 6 in the first 250 m downstream although mixing is commonly incomplete in this zone large stream discharge volumes in rain events dilute the neutralising material input thus driving the ph back towards 4 downstream of treatment more complete neutralisation is achieved 4 km downstream even in major rain events and ph can rise to 7 partial neutralisation is sufficient to remove most of the dissolved fe iii typically 30 mg l from the mangatini stream in the first 10 m and remaining dissolved fe is essentially all fe ii which decreases over time as it oxidises and precipitates dissolved al in the mangatini stream typically 50 mg l decreases steadily downstream over 100 m in the limestone mixing zone precipitated fe and al form amorphous oxyhydroxides that are transported as suspended solids and deposited on the stream bed with excess limestone in zones of low flow velocity dissolved zn is removed from solution by adsorption to fe oxyhydroxide when ph reaches 5 but dissolved ni remains in solution despite the neutralisation process gypsum precipitation occurs throughout the limestone mixing zone resulting in at least 30 decrease in dissolved so 4 2 minor ettringite forms in the first 100 m but then probably redissolves the limestone dosing system is an effective method of neutralising the effects of amd and removing most dissolved metals in a steep mountain stream with frequent rain events where this dynamic environment places many constraints on treatment options

forward modelling of carbonate platforms sedimentological and diagenetic constraints from an application to a flat topped greenhouse platform triassic southern alps italy abstract quantitative analysis of depositional systems using numerical models can provide insights into the interaction of sedimentological and diagenetic processes difficult to interpret from observation of the geological products alone numerical models can highlight the interactions between controlling parameters and generate best estimate simulations of case studies from the geological record different data sources e g outcrop data uniformitarian constraints paleogeography need to be considered in the process of defining the parameters required to produce models that honour individual case studies we present a best estimate forward model of a high relief triassic carbonate platform southern alps italy generated using carb3d a 3d process based forward modelling package able to simulate sedimentary facies geometries and early diagenesis of isolated carbonate platforms the parameters used for the presented forward model have been deduced by the study of architectural sedimentological and diagenetic features of the platform and by data from modern and ancient analogues sensitivity analysis is used to tune values of the parameters within ranges defined from field laboratory and uniformitarian constraints critical evaluation of the model allowed 1 verification of the validity of the used parameters 2 evaluation of the interaction between controlling parameters 3 development of a numerical model that can be used for quantitative elaborations furthermore the process of generating the numerical model required a detailed interpretation of field and laboratory data crucial to define the required input parameters modelling the studied carbonate platform also enabled evaluation of the effects of the interaction between productivity environmental energy and creation of accommodation space promoting the understanding of their role on the architecture of carbonate systems forward modelling also allows the integration of data from conventional data sets with data from present day observations and seismic geometries promoting a transition from a qualitative to a semi quantitative quantitative sedimentological approach forward models can further be used to parameterise petrophysical properties of complex geobodies with potential application for the management of georesources

internal structure of the dead sea leaky transform rift in relation to plate kinematics abstract the structures along the dead sea transform rift are related to the motions of the sinai and arabia plates which border it and to the irregularities of their boundaries the total slip was 105 km left lateral but the present structures were formed mainly during the last 40 km of slip which probably occurred in the plio pleistocene along the southern half of the transform the strike slip motion takes place on en echelon faults this produces rhomb shaped grabens or pull aparts which are sometimes composite and in which there is local crustal separation thus much of the transform is leaky these structures occur in a morpho tectonic rift valley delimited by normal faults which express a small component of transverse extension along a few segments the shape of the transform is such that lateral motion produces local transverse compression the geometric relations of the structures along the transform define an eulerian pole of relative plate motions at 32 8 n 22 6 e 0 5 the older motion was somewhat different and is described by a pole located about 5 west of the above then the component of transverse extension and crustal separation was much smaller than now while local transverse compression was more important the northern half of the dead sea transform has an irregular shape and the bordering plates did not remain rigid as lateral motion continued here transverse compression is often important

sequence stratigraphy of the red river formation williston basin usa stratigraphic signature of the ordovician katian greenhouse to icehouse transition abstract the upper katian upper ordovician red river formation is a carbonate evaporite supersequence that formed in the epicratonic williston basin of western north america this study focuses on the upper part of the formation in the southern us part of the basin the studied succession is made up of three transgressive regressive sequences rr1 rr2 and rr3 each 0 5 1 m y in duration and composed of relatively few meter scale high frequency cycles parasequences sequence boundaries are characterized by intraclastic breccia laminated dolomite successions that have been truncated and capped by evaporite deposits subaqueous anhydrites within each sequence represent evaporite lowstand systems tracts lsts that formed during relative sea level lows that lead to the precipitation of gypsum later recrystallized into anhydrite in a quiet salina type environment transgressive tst and early highstand systems tracts hst are composed of subtidal facies of predominantly skeletal mudstone to wackestone packstone with abundant burrow mottling late hsts are predominantly composed of peritidal porous laminated dolomite the study illustrates how the sequence stratigraphic framework of carbonate evaporite deposits from the williston basin relates to the late ordovician glacio eustasy transitional climates and low basin subsidence in an arid setting

holocene millennial to centennial carbonate cyclicity recorded in slope sediments of the great bahama bank and its climatic implications a 38 m long sediment core md992201 retrieved from a water depth of 290 m from the leeward margin of the great bahama bank gbb 25 53 49 n 79 16 34 w has been investigated for changes in aragonite content the core covers the mid to late holocene the past 7230 yr sediment lightness l values was used as a proxy for aragonite content based on a high linear correlation r 0 93 between the x ray diffraction derived aragonite content and l values the resulting time resolution of the l values derived aragonite content ranges from 1 yr at the base of the core to 4 yr at the top detailed time series analysis using monte carlo singular spectrum analysis and spectral analysis lomb scargle fourier transform identifies the presence of seven signals with varying amplitudes and wavelengths that could be traced throughout the past 5500 yr during the first 1600 yr of sedimentation the aragonite record is dominated by the initial flooding of the flat topped gbb superimposed on a multimillennial signal related to holocene sea level changes a millennial scale fluctuation and five quasi periodic oscillations were detected 1 3 2 kyr 500 600 yr 380 yr 260 yr 200 yr and 100 yr period comparisons with other proxies e g tree ring 14c 10be and 18o in ice cores provides information on the origin and dynamics of the individual signals the analysis shows that the 200 yr and 100 yr signals can be attributed to solar forcing the 260 yr 380 yr and the 500 600 yr quasi periodic signals are found to be of climatic origin whereas the millennial scale fluctuations remain enigmatic although solar forcing mechanisms seem likely the data show that variability of solar output as well as past oceanographic and atmospheric changes have modulated the mid to late holocene climate which in turn controlled sediment input variations found in the holocene wedge leeward of the gbb although these periplatform sediments have a rather uniform appearance they still contain a large variety of subtle sedimentary variations

mantle fluids in the karakoram fault helium isotope evidence abstract the karakoram fault kkf is the 1000 km long strike slip fault separating the western himalaya from the tibetan plateau from geologic and geodetic data the kkf is argued either to be a lithospheric scale fault with hundreds of km of offset at several cm a or to be almost inactive with cumulative offset of only a few tens of kilometers and to be just the upper crustal localization of distributed deformation at depth here we show 3he 4he ratios in geothermal springs along a 500 km segment of the kkf are 3 100 times the normal ratio in continental crust providing unequivocal evidence that a component of these hydrologic systems is derived from tectonically active mantle mantle enrichment is absent along the indus yarlung suture zone isz just 35 km southwest of the kkf suggesting that the mantle fluids flow only within the kkf within the last few ma the kkf must have accessed tectonically active tibetan mantle northeast of the mantle suture which we therefore locate vertically beneath the kkf very close to the surface trace of the isz hence in southwestern tibet indian crust may not now be underthrusting substantially north of the isz even though miocene underthrusting may have placed indian crust north of the isz in the lower half of the tibetan plateau crust this is in significant contrast to central and eastern tibet where underthrust indian material not only forms the lower half of the tibetan crust but is also currently underthrusting for 200 km north of the isz our new constraint on kkf penetration to the mantle allows an improved description of the continuously evolving karakoram fault as a tectonically significant yet perhaps geologically ephemeral lithospheric structure

helium neon and argon systematics of the european subcontinental mantle implications for its geochemical evolution in this study we present a comprehensive noble gas study of mantle xenoliths from various european cenozoic volcanic provinces the main body of samples is from the massif central france and the eifel germany smaller subsets of samples are from spitsbergen and the graz basin austria in all the helium neon and argon isotopic abundances of a total of forty five mantle xenoliths phenocrysts and xenocrysts were determined the 3he 4he ratios within each volcanic province are very uniform irrespective of the diverse lithologies and p t conditions which are represented by our sample suite mean 3he 4he ratios of the massif central eifel spitsbergen and kapfenstein are 6 53 25 6 03 14 6 65 25 and 6 1 7 1 times the atmospheric ratio ra respectively the strontium and neodymium isotopic composition of some of the cpx separates are highly variable and therefore in contrast to the uniform he signature we thus conclude that he and probably also the other noble gases in the xenoliths are effectively decoupled from the non volatile elements therefore the he signature that is preserved in the xenoliths is actually that of their host magmas published strontium neodymium and lead isotope data of the unevolved host magmas of the xenoliths correlate well with our xenolith he data the position of the fields of the investigated volcanic provinces in hesr hend and hepb variation diagrams depict ternary mixtures between dmm em himu endmembers as the source the host magmas and their volatiles the neon isotopic composition of the gases released from the xenoliths is in most cases atmospheric and probably reflects atmospheric contamination only a few samples reveal indications for morb type ne or evidence of mass fractionation the 40ar 36ar ratios of the xenoliths are mostly radiogenic with the highest ratio being 17 000 however all samples have suffered a certain degree of atmospheric contamination we calculate that the uncontaminated 40ar 36ar ratio of the european subcontinental mantle is 30 000 the4he 40ar ratios have been fractionated since with values around 0 25 they are below both the current production ratio and the morb ratio they cannot be explained by atmospheric contamination as the samples with high 40ar 36ar ratios also have low 4he 40ar ratios helium and ar were probably fractionated during initial closed system degassing of the host magma we calculate the original unfractionated 4he 40ar ratios of the massif central and eifel magma source which are 2 56 18 and 2 71 17 respectively the noble gas systematics are compatible with the notion that addition of crustal material has modified a former morb source signature we use our mean 3he 4 he ratios and reconstructed 4he 40ar ratios to model the time and degree of contamination of a morb like source with crustal material combining our model with evidence from published oxygen strontium neodymium and lead isotope data we judge that the source of the massif central and eifel magmas became enriched in k u and th shortly prior or during the variscan orogeny pre collisional collisional in this case the enrichment in these elements is therefore most probably related to subduction of crustal material in a destructive continental margin setting

tropical marine climate during the late paleozoic ice age using trace element analyses of brachiopods abstract the late paleozoic ice age can be considered an important analogue to the modern ice age but comparisons between the two time intervals have been hampered by the difficulty of resolving climatic changes that occur over short e g seasonal time scales in the paleozoic record as a first step toward overcoming these limitations this study employed mg ca trace element ratios sampled across the growth bands of six specimens of the brachiopod composita to assess differences in tropical marine mean temperature and seasonality in visean and moscovian time these time intervals bracket the onset of the late paleozoic ice age which occurred in mid serpukhovian time and thus provide a snapshot of climate changes from a greenhouse to an icehouse world shells were screened for diagenetic alteration by cathode luminescence and by comparing the values of mn sr na and b to those reported for modern brachiopods in addition a 87sr 86sr value measured for one specimen agreed with a published strontium isotope curve for the late paleozoic era both the mean and range of mg ca values were larger in visean than moscovian time suggesting colder and less seasonal temperatures during the late paleozoic ice age the decline in seasonality was due to a greater proportional reduction of maximum values which presumably represent summer temperatures than minimum values these relative differences between the pre ice age and ice age tropical climate provide a first step toward understanding the broad patterns of seasonal scale changes in temperature during a critical time in earth s history

whiting related sediment export along the middle miocene carbonate ramp of great bahama bank modern aragonite needles are present all along the modern leeward margin of great bahama bank odp leg 166 while middle miocene sediments contain needles only in more distal areas sites 1006 and 1007 in contrast to the rimmed flat topped platform topography during the plio pleistocene the miocene great bahama bank morphology is a carbonate ramp profile this might imply a different location and precipitation type for miocene aragonite needles in this study aragonite needles in miocene sediments were isolated using a granulometric separation method furthermore the isolation of the various carbonate components enables the identification of primary versus diagenetic components the miocene aragonite needles are concentrated in the finest granulometric sediment fractions 12 m the fraction specific geochemical analyses 13c 18o and sr elemental abundance represent useful tools to assess the possible sources of the aragonite mud the geochemical variation of the fractions rich in pristine aragonite needles and the characteristics of the needle morphology point to whiting phenomena as the main sediment source and algal fragmentation as a minor component both components indicate shallow water environments as the main sediment source area ramp top related fine grained particles now present at distal sites were likely exported as suspended material similar to present day transport mechanisms the scarcity of needles at proximal sites is probably linked to hydrodynamic processes but dissolution and recrystallization processes cannot be excluded the granulometric separation approach applied here enables a better characterization of the finest carbonate particles representing an important step towards the discrimination between primary and diagenetic fine grained components

sources of environmental sulfur in the groundwater system southern new zealand abstract sulfide minerals commonly occur in sediments and basement rocks in southern new zealand as authigenic precipitates from groundwater below the oxygenated surface zone there are two principal potential sources for sulfur in the groundwater system weathering of sulfide minerals in the metamorphic basement and rainwater derived marine aerosols we present data for these two key sulfur sources metamorphic sulfide and associated hydrothermal au bearing veins within the otago schist average 34s 1 8 2 4 and an inland saline lake s derived entirely from rainwater 34s 21 4 0 8 we use these two end member 34s values to estimate the contributions of these sources of sulfur in authigenic groundwater sulfide minerals and in waters derived from oxidation of these sulfide minerals across a range of environments we show that authigenic groundwater pyrite along joints in the otago schist is derived primarily from metamorphic basement sulfur in contrast authigenic groundwater pyrite cementing miocene recent aquifers shows a substantial marine aerosol component and represents a distinct hydrogeological system we suggest that marine aerosols represent a significant flux to the terrestrial sulfur cycle that has been present through the groundwater system in otago over the past 20 million years

oxygen isotope composition of natural waters in the mt etna area oxygen isotopes of both rainwater and groundwater samples from mt etna were used to obtain information on recharge areas flow paths and the origin of wet air masses oxygen isotope composition was determined in rainwater samples collected for a period of 3 years october 1997 october 2000 in 11 rain gauges distributed along the flanks of mt etna from sea level to 2900 m of altitude values ranged from 213 8 to 1 9 the lowest values being measured at higher altitudes and or during cooler periods for rain gauges located from sea level up to 1000 m altitude volume weighted values defined an isotopic gradient of 22 7 km which is in the range observed in the mediterranean area higher altitude gauges yielded a much lower gradient 2 0 6 km probably due to the fact that vapour condensing at higher altitudes was mixed with an 18 o rich volcanic component deriving from the huge vapour output of the summit craters the oxygen isotope composition of about 210 groundwater samples collected all around the volcano ranged from 2 9 3 to 2 5 0 the higher values measured on the eastern flank indicated that recharge occurs at lower altitudes on this flank the low variability 0 30 0 65 of the monthly values gathered from 14 groundwater sampling points over a period of 2 years indicates that the groundwater system is isotopically well mixed some long term trends may be explained by variations in annual recharge due to the prevalent isotope composition of wet air masses q 2004 elsevier b v all rights reserved

arsenic copper and zinc occurrence at the wangaloa coal mine southeast otago new zealand abstract waste piles created from open cast coal mining activities at the abandoned wangaloa mine in se otago have exposed pyrite fes2 to atmospheric conditions this has led to the acidification of the surface tailings and nearby drainage waters acid mine drainage amd mobilisation of trace metals arsenic as copper cu and zinc zn has occurred partly as a result of the low ph levels ca ph 2 4 leading to elevated concentrations of these metals in receiving waters authigenic pyrite deposited in a marginal marine coal forming environment is enriched in as with levels reaching up to 100 ppm copper and zn in solid solution are not elevated above background levels in either coal measures or associated pyrite water discharges sediments waste rock and background samples were sampled and analysed during the driest summer and wettest winter seasons of 1998 and 1999 during the winter season water discharging from the waste piles contained up to 0 7 ppm mg kg as as measured in 1998 during the 1999 wettest season no such levels of as were observed with the highest level attaining 0 07 ppm as copper and zn were locally elevated in waters with zn concentrations reaching 1 ppm during the summer season of 1999 only one sampling site recorded elevated metal concentrations adverse effects from the remnant waste piles appear to be highly localised due to downstream natural remediation processes occurring in a wetland area the absence of strongly elevated metal concentrations during the drier season is a result of strongly depressed water levels within the waste piles flushing of acid and metals occurs when the water levels increase with the onset of the winter season during the summer season pyrite within the waste piles has been readily decomposing from the increased availability and transport of atmospheric oxygen

insights into mantle type volatiles contribution from dissolved gases in artesian waters of the great artesian basin australia abstract the geochemical features of the volatiles dissolved in artesian thermal waters discharged over three basins millungera galilee and cooper basin of the australian great artesian basin gab consistently indicate the presence of fluids from multiple gas sources located in the crust e g sediments oil reservoirs granites as well as minor but detectable contributions of mantle magma derived fluids the gases extracted from 19 water samples and analyzed for their chemical and isotopic composition exhibit amounts of co2 up to about 340 mlstp lh2o marked by a 13ctdc total dissolved carbon ranging from 16 9 to 0 18 vs pdb while ch4 concentrations vary from 4 4 10 5 to 4 9 mlstp lh2o helium contents were between 9 and 2800 times higher than equilibrium with air saturated water asw with a maximum value of 0 12 mlstp lh2o helium isotopic composition was in the 0 02 0 21 ra range ra air normalized 3he 4he ratio the three investigated basins differ from each other in terms of both chemical composition and isotopic signatures of the dissolved gases whose origin is attributed to both mantle and crustal volatiles mantle he is present in the west central and hottest part of the gab despite no evidence of recent volcanism we found that the partial pressure of helium significantly higher in crustal fluids than in mantle type volatiles enhances the crustal he signature in the dissolved gases thus masking the original mantle contribution neotectonic activity involving deep lithospheric structures and magma intrusions highlighted by recent geophysical investigations is considered to be the drivers of mantle magmatic volatiles towards the surface the results although pertaining to artesian waters from a vast area of 542 000 km2 provide new constraints on volatile injection and show that fluids geochemistry can provide additional and independent information on the geo tectonic settings of the great artesian basin and its geothermal potential

computer modeling the internal architecture of carbonate platforms a numerical computer model is described that calculates the internal architecture of carbonate platforms in response to varying values of carbonate production subaerial and submarine erosion sediment redeposition and sea level changes the computer generated sections closely resemble large scale outcrops and interpreted seismic profiles through carbonate platforms stillstand and transgressive sequences have prograding and downlapping platform geometries with lagoons developing in transgressive systems regressive sequences have downlapping clinoforms and erosional upper surfaces glacioeustatic scale cycles have a major control on platform geometry with erosional sequence boundaries developing during low stands and platform drowning occurring during transgressive periods lowstand downlapping wedges are minor features when compared with clastic systems and major progradation and downlap of slope deposits develop with transgressions and flooding of platform tops carbonate erosion rates are varied and have an important effect on the morphology of foodback surfaces which have a major control on platform top production the computer program contributes to the analysis of carbonate systems in two ways it gives a visual picture of the quantitative effects of the many parameters controlling carbonate geometries and it aids quantitative analysis of the architectures and time scales of ancient outcrop or seismic sequences

holocene atlantic climate variations deduced from carbonate periplatform sediments leeward margin great bahama bank a marine sediment core from the leeward margin of great bahama bank gbb was subjected to a multiproxy study the aragonite dominated core md992201 comprises the past 7230 years in a decadal time resolution and shows sedimentation rates of up to 13 8 m kyr aragonite mass accumulation rates age differences between planktonic foraminifera and aragonite sediments and temperature distribution are used to deduce changes in aragonite production rates and paleocurrent strengths aragonite precipitation rates on gbb are controlled by exchange of carbonate ions and co2 loss due to temperature salinity conditions and biological activity and these are dependent on the current strength paleocurrent strengths on gbb show high current velocities during the periods 6000 5100 years bp 3500 2700 years bp and 1600 700 years bp lower current speeds existed during the time intervals 5100 3500 years bp 2700 1600 years bp and 700 100 years bp bahamian surface currents are directly linked to the north atlantic atmospheric circulation and thus periods with high low current speeds are proposed to be phases of strong weak atmospheric circulation

quaternary atoll development new insights from the two dimensional stratigraphic forward modelling of mururoa island central pacific ocean knowledge about the quaternary evolution of mid ocean atolls comes mainly from drilling and field observations carried out on a number of pacific carbonate islands however little is known about the early to mid pleistocene atoll development history especially at margin and foreslope settings using previous field and subsurface data from mururoa atoll and a process based modelling software dionisos a two dimensional forward stratigraphic model of atoll development is proposed for the past 1 8 million years myr observational data from vertical to inclined coring seismic and bathymetric surveys indicate that from approximately 0 45 to 0 40 million years before present ma carbonate deposition at mururoa atoll resulted in a series of mostly prograding reef units the model is first constrained at the base by the shape and topography of the pre quaternary basement a number of sensitivity tests were performed to define the respective influence of variant parameters the best fit development scenario that accounts for the overall geometry and stratigraphic architecture of the quaternary sediment packages is obtained by using the sea level curve by miller et al 2005 uniform subsidence rate of 105 m myr 1 and carbonate production rates gradually increasing from 0 50 to 8 mm yr 1 between 1 80 ma and the present additional controlling parameters include subaerial erosion at a constant rate of 0 25 m kyr wave energy and sediment transport processes the stratigraphic forward model predicts a succession of three distinct types of carbonate systems that have developed since the earliest pleistocene toe of slope systems from 1 80 ma to about 0 80 ma open platform systems from 0 80 ma to 0 50 ma and framework reef systems from about 0 50 ma to the present the development of these different systems is most likely to be controlled by climate and changes in sea level cycles during the low amplitude 41 kyr cycle periods of the earliest pleistocene ambient conditions were not conducive to framework reef growth shallow water carbonate sedimentation was dominantly gravity driven operating along the platform foreslopes only during the mid pleistocene climate transition narrow open platform units have developed at the upper parts of the pre quaternary basement flanks with the onset of the high amplitude 100 kyr sea level modes and climate restoration reef frameworks started to be generated these models from mururoa agree with a number of previous studies suggesting that most of the true framework reefs were not initiated prior to 0 50 ma mururoa atoll is demonstrated to be a robust analogue for providing more realistic interpretations of the development history of pacific atolls further modelling with three dimensional dionisos could generate better predictions by taking into account hydrodynamic and transport parameters more accurately

computer simulation of reef growth light is one of the major controls on reef growth and carbonate production the growth of present reef builders depends largely upon the amount of light available for photosynthesis as light decreases with water depth so does reef growth the computer model presented extends this principle by combining two functions one for photosynthesis and the other for the extinction of light in water the model is used to simulate the growth of alacran reef mexico two reefs of the great barrier reef and the reefs of the windward platform of st croix us virgin islands the model also gives an accurate simulation of the growth of fore reef walls in belize in agreement with the accretion hypothesis developed for this feature

long term 1997 2007 geochemical monitoring of gases from the umbria marche region abstract the paper presents the results of ten year long geochemical monitoring carried out in the area hit by the 1997 98 umbria marche seismic sequence northern apennines italy showing the advancement in our understanding of the reciprocal relationships between fluids and tectonic structures in this area long term geochemical monitoring has allowed us to define the geochemical features of the gas phase and to model its origins and interactions all the released gases including dissolved and venting gases have predominantly crustal origin and have suffered from substantial modifications in their geochemical features the whole seismogenic process is considered to be responsible for the modifications recorded over a wide time interval including the production of co 2 from mechanical stress on carbonate rocks we interpret the modifications occurred to the gas phase during the 1997 98 period as related to faulting activity while those recorded after the end of the seismic crisis are interpreted as being a consequence of the crustal relaxation the data show that it is almost impossible to interpret the temporal variation without coupling long term geochemical monitoring and knowledge of the genetic features of the fluids therefore the information coming from the circulating fluids is a powerful tool to better understand the physical processes governing the faulting activity

pollution of osheepcheon creek by abandoned coal mine drainage in dogyae area eastern part of samcheok coal field kangwon do korea osheepcheon creek running through the dogyae area is being polluted by the influx of the abandoned coal mine drainage generally the more polluted water has lower ph and eh and higher conductivity values the concentrations of mg ca fe so4 and some trace elements such as cd co cr mo ni pb rb sr u and zn are tens to hundreds of times more concentrated in the abandoned coal mine drainage than in the unpolluted streamwater however most immobile toxic pollutants from the mine drainage are quickly removed from the streamwater by the precipitation of amorphous fe hydroxide and sorption on the precipitated fe hydroxide the fast removal of the pollutants from the streamwater maintains the water quality of the creek as acceptable at most places along the stream path except where the abandoned coal mine drainage flows in however the creek has the potential of deteriorating quickly if the mine drainage is allowed to be continuously combined with the streams a function of ph eh and conductivity has been developed with discriminant function analysis for the purpose of easy fast and inexpensive measurement of the degrees of pollution of the streams the estimated pollution of the streams with the discriminant function are consistent with what the chemical compositions of the water samples indicate the pollution map of the study area was constructed from the calculated scores with the discriminant function the pollution map suggests that the pollutants mainly come from the west side of osheepcheon creek thus the abandoned coal mine drainage from the west side has to be appropriately treated as soon as possible to prevent osheepcheon creek from being further polluted considering the topography climate and the amount of the mine drainage an active treatment method is recommended

abiotic methane on earth 1 over the last 30 years geochemical research has demonstrated that abiotic methane ch4 formed by chemical reactions which do not directly involve organic matter occurs on earth in several specific geologic environments it can be produced by either high temperature magmatic processes in volcanic and geothermal areas or via low temperature 100 c gas water rock reactions in continental settings even at shallow depths the isotopic composition of c and h is a first step in distinguishing abiotic from biotic including either microbial or thermogenic ch4 herein we demonstrate that integrated geochemical diagnostic techniques based on molecular composition of associated gases noble gas isotopes mixing models and a detailed knowledge of the geologic and hydrogeologic context are necessary to confirm the occurrence of abiotic ch4 in natural gases which are frequently mixtures of multiple sources although it has been traditionally assumed that abiotic ch4 is mainly related to mantle derived or magmatic processes a new generation of data is showing that low temperature synthesis related to gas water rock reactions is more common than previously thought this paper reviews the major sources of abiotic ch4 and the primary approaches for differentiating abiotic from biotic ch4 including novel potential tools such as clumped isotope geochemistry a diagnostic approach for differentiation is proposed

field and modelling studies of cambrian carbonate cycles virginia appalachians reply abstract field studies coupled with computer modelling of carbonate cycles in the elbrook conococheague formations middle to upper cambrian in the appalachians have helped define the mechanisms of formation the sequence is up to 1 6 km thick and composed of cyclic peritidal carbonates these formed on an aggraded rimmed shelf on a mature passive continental margin the cycles 1 7 m thick have lower parts of subtidal intertidal carbonate and caps of dolomitic laminite containing minor quartz arenite shale and breccia sedimentation rates for these peritidal carbonate environments exceeded long term subsidence of the platform 0 01 to 0 1 m 1 000 yr thus the shelf stayed near to sea level i e was aggraded milankovitch 20 000 to 100 000 yr low amplitude sea level fluctuations few meters superimposed on 3rd order sea level fluctuation of 1 to 3 m y duration and less than 20 m amplitude caused periodic submergence of the gently sloping platform less than 0 02 m km slopes resulting in deposition of over 400 peritidal cycles in about 26 m y cycles that formed during 3rd order sea level rise are thick and limestone rich whereas those formed during 3rd order fall are thin quartzose and highly dolomitized the modelling suggests that fewer and thinner cycles formed during the long term falls compared to the rises reflecting decreased accommodation cycle frequency decreases into areas of lower subsidence rate open marine cycles typical of the outer shelf and cycles formed during 3rd order sea level rise contain digitate bioherms grainstone and ribbon carbonates in lower parts they reflect high subsidence rate and an open marine setting inner shelf cycles and cycles that formed during 3rd order sea level fall commonly are thrombolitic or have thin subtidal parts grainstone conglomerate or stromatolite and reflec the low subsidence rates interior areas of quaternary carbonate shelves are characterized by incipiently drowned facies and pinnacle reefs and are punctuated by soil caliche horizons and karst surface that reflect 100 m glacio eustatic sea level fluctuations in contrast many ancient shelves like the cambro ordovician shelf of the appalachians were flat topped and dominated by cyclic peritidal sequences lacking evidence of high amplitude sea level fluctuations such aggraded shelves may represent the typical state of mature carbonate shelves that formed in response to low amplitude milankovitch sea level fluctuations as opposed to the large scale fluctuations that typified the quaternary

kinematic consistency between the dead sea fault zone and the neogene and quaternary left lateral faulting in se turkey a revised quantitative kinematic model has been determined for the dead sea fault zone dsfz and the left lateral fault zones in se turkey the relative motions of the african and arabian plates across the dsfz are represented by relative rotation about 31 1 n 26 7 e at 0 40 0 02 ma 1 the northern dsfz in syria and southern turkey is interpreted for the first time as a series of transpressional stepovers along which the left lateral slip rate is substantially less than the rate of relative plate motion because this slip is oblique to the plate motion the slip rate on the east anatolian fault zone eafz is estimated as 8 mm a 1 restoring its observed slip thus requires its age to be 4 ma the previous phase of deformation which involved slip on the malatya ovacik fault zone mofz before the eafz came into being is thus dated to 7 4 ma suggesting initiation of the north anatolian fault zone nafz at 7 ma not 5 ma as previously thought the total left lateral slip on the northern dsfz in southernmost turkey is estimated as at least 65 km partitioned with 45 km on the amanos fault 10 km on the east hatay fault and a further 10 km on the kirkpinar fault farther east much of this slip is inferred to have occurred during the miocene before the modern geometry of this plate boundary zone developed when it first formed the af ar plate boundary was relatively complex it initially reactivated preexisting structures in the palmyra foldbelt in syria and in the gaziantep region of southern turkey which were significantly misaligned relative to the plate motion requiring major components of shortening as well as left lateral slip the transition from this initial rather diffuse geometry to the present localised geometry of the dsfz across western syria occurred within the miocene the predicted rate of relative motion between the stable interiors of the turkish and african plates in the vicinity of their common boundary onshore of iskenderun gulf in southern turkey is estimated as westward at 9 mm a 1 however this promontory of the african plate is itself moving westward relative to the stable interior of this plate at 7 8 mm a 1 the rate of localised left lateral slip on the onshore part of this boundary the ne trending yakapinar goksun fault is thus estimated as only 2 mm a 1 this locality can also be regarded as within the distributed boundary zone between the turkish and arabian plates the estimated relative motion between these plates is at 8 7 mm a 1 towards the ssw partitioned between localised left lateral slip at 2 mm a 1 on the yakapinar goksun fault and at least 1 mm a 1 on the amanos fault and 2 5 mm a 1 on east hatay fault with at most distributed left lateral simple shear at 3 2 mm a 1 across the amanos mountains in between however the combined slip on left lateral faults east of the amanos mountains may be as high as 6 mm a 1 with slip at 1 7 mm a 1 on the amanos fault and at 4 3 mm a 1 on the east hatay fault and any active faults farther east this requires no more than 0 7 mm a 1 of distributed simple shear across the amanos mountains raising the possibility that this component of deformation may in fact be zero this small nonzero estimate possibly indicating a closure error arising from minor errors in predicted values of other relative motion vectors it is proposed that this boundary between the turkish and african plates first developed at the same time as the mofz and nafz but its original geometry involving left lateral slip on the karatas osmaniye fault has since become locked by the presence of relatively strong ophiolitic crust within this fault zone this quantitative kinematic model demonstrates for the first time how it is possible for the left lateral faulting accommodating the nnw sse relative motion between the arabian and african plates in nw syria to dovetail into the left lateral faulting accommodating the wsw ene relative motion between the turkish and arabian plates in se turkey

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

abiotic methane flux from the chimaera seep and tekirova ophiolites turkey understanding gas exhalation from low temperature serpentinization and implications for mars abstract the emission of abiotic methane ch 4 into the atmosphere from low temperature serpentinization in ophiolitic rocks is documented to date only in four countries the philippines oman new zealand and turkey serpentinization produces large amounts of hydrogen h 2 which in theory may react with co 2 or co to form hydrocarbons fischer tropsch type synthesis ftt similar mechanisms have been invoked to explain the ch 4 detected on mars so that understanding flux and exhalation modality of ophiolitic gas on earth may contribute to decipher the potential degassing on mars this work reports the first direct measurements of gas ch 4 co 2 flux ever done on onshore ophiolites with present day serpentinization we investigated the tekirova ophiolites at cirali in turkey hosting the chimaera seep a system of gas vents issuing from fractures in a 5000 m 2 wide ophiolite outcrop at this site at least 150 190 t of ch 4 is annually released into the atmosphere the molecular and isotopic compositions of c 1 c 5 alkanes co 2 and n 2 combined with source rock maturity data and thermogenic gas formation modelling suggested a dominant abiotic component 80 90 mixed with thermogenic gas abiotic h 2 rich gas is likely formed at temperatures below 50 c suggested by the low deuterium hydrogen isotopic ratio of h 2 d h2 720 consistent with the low geothermal gradient of the area abiotic gas synthesis must be very fast and effective in continuously producing an amount of gas equivalent to the long lasting 2 millennia emission of 100 t ch 4 yr 1 otherwise pressurised gas accumulation must exist over the same ophiolitic formation 3 km away from chimaera we detected an invisible microseepage of abiotic ch 4 with fluxes from 0 07 to 1 g m 2 d 1 on mars similar fluxes could be able to sustain the ch 4 plume apparently recognised in the northern summer 2003 10 4 or 10 5 t yr 1 over the wide olivine bedrock and outcrops of hydrated silicates in the syrtis major and nili fossae just one seep like chimaera or more realistically a weak spatially sporadic microseepage would be sufficient to maintain the atmospheric ch 4 level on mars

arsenic speciation in waters and sediment of ephemeral floodplain pools rios agrio guadiamar aznalcollar spain abstract the april 1998 breaching of the aznalcollar tailings dam at boliden apirsa s spanish aznalcollar los frailes ag cu pb zn mine resulted in the flooding of the rios agrio and guadiamar with arsenic as rich tailings and water mineralogical and geochemical characterisation of water and sediment from five ephemeral pools on the agrio guadiamar floodplain has been carried out to understand how the as is sequestered and to evaluate the long term stability of the as bearing phases dissolved as concentrations in pool waters range from an extreme of 85 000 g l 1 down to 5 5 g l 1 xanes exafs xrd x ray mapping electron microprobe analysis and single chemical extractions suggest that as in the sediments is sequestered in sulphide as 0 in arsenopyrite and pyrite coordinated by 1 s and 3 fe and in fe oxide asv in arsenate coordinated by 4 o bound to fe oxide and fe sulphate probably jarosite the pools evolved as a result of the interaction of rainwater with the sediments and as concentrations are controlled by evaporation and by the amount of tailings and specifically arsenopyrite in the sediments that remained even after clean up efforts the arsenopyrite remaining in the floodplain sediment is potentially highly reactive under the prevailing ph and eh conditions on the floodplain and will probably continue to provide as to ephemeral pools and possibly agrio guadiamar river water

ichnology and depositional environments of the upper ordovician stony mountain formation in the williston basin canada refining ichnofacies and ichnofabric models for epeiric sea carbonates abstract ordovician epeiric sea carbonates in intracratonic basins of laurentia are enigmatic due to their unique depositional settings and the absence of modern analogs integrated ichnologic and sedimentologic analysis of the upper ordovician stony mountain formation in the williston basin of canada allows recognition of neritic marine nearshore marine open lagoon restricted lagoon peritidal sand shoal and peritidal flat subenvironments the cruziana ichnofacies occurs in neritic between fair weather and storm wave bases and nearshore around fair weather wave base marine environments the depauperate cruziana ichnofacies is present in open and restricted lagoon environments indicating a shift from fully marine to stressed conditions in the open lagoon composite ichnofabrics related to omission surfaces illustrate the low rates of background sedimentation interrupted by event deposition and early cementation illustrating the glossifungites and trypanites ichnofacies the decreased size of discrete burrows in the restricted lagoon is attributed to reduced oxygenation under stagnation rather than hypersalinity the peritidal complex includes high energy sand shoals and low energy tidal flats only monospecific colonization took place sporadically in associated subtidal environments within the peritidal complex deposits

a study on the active crustal deformation of the north and east anatolian fault zones abstract active crustal deformation in the north anatolian fault zone nafz and the east anatolian fault zone eafz based on seismicity data is examined the results show that the deformation in the nafz is taken up by extension on an azimuth of 59 at a rate of 27 mm yr and as compression on an azimuth of 149 and a rate of 20 mm yr the average dextral lateral motion on the naf is about 23 mm yr this motion in the western part of the naf is 16 mm yr while it increases in the eastern part of the fault to 27 mm yr in the eafz the deformation is taken up as nearly n s compression n7 e at a rate of 5 mm yr and as nearly e w extension n97 at a rate of about 9 mm yr the average sinistral lateral motion has a rate of about 6 mm yr the expected slip rates from plate motions along the north anatolian fault are of the order of 38 mm yr the predicted slip rates for east anatolian fault are 19 mm yr or 29 mm yr the seismicity of the last 140 years can account for the expected deformation along the nafz for the eafz however it is possible that part of the total deformation has been expressed aseismically

accommodation and sedimentary architecture of isolated icehouse carbonate platforms insights from forward modeling with carb3d abstract a fundamental control on the evolution of carbonate platforms is accommodation the space available for sediment deposition here we adopt a sensitivity analysis approach using the process based forward model carb3d to quantitatively investigate the sedimentary response of isolated carbonate platforms to individual accommodation drivers of eustasy subsidence and surface dissolution sediment production the mechanism invoked to fill accommodation is also investigated fourth order milankovich driven sea level cycles dominate icehouse carbonate sedimentology with 400 ky cycles modulating the effect of 100 ky cycles of comparable magnitude when both cycles are present both overwhelm higher frequency lower amplitude fifth order cycles which are rarely preserved on the platform top subsidence is a fundamental control on sedimentary stacking patterns sequence boundary frequency sbf and platform geometry with rapid subsidence increasing the preservation of platform top sequences most icehouse platforms are subject to extended periods of platform top exposure missed beats when the platform top remains emergent at a sea level maximum are common and create non milankovich sbfs furthermore during platform emergence surface lowering via surface dissolution also creates accommodation for the subsequent platform flooding event with surface dissolution rates in humid climates comparable to moderate rates of subsidence however accommodation generation by surface dissolution is self limiting in as much as accommodation generated by dissolution is rapidly refilled on flooding sediment production is a key control on unfilled accommodation which our simulations suggest is considerable on icehouse platforms increased shallow water 3 m depth sediment production enhances intra platform bathymetric relief between the margin and interior this is driven in large part by a higher sedimentation rate at the margin than in the interior platforms can be flooded to depths up to 45 m during marine transgressions and accommodation often remains unfilled there are two distinct phases of platform top sedimentation during the transgression and early highstand platform margins accumulate at a greater rate than interior sediments generating differential intra platform bathymetry subsequently accommodation in the interior fills by forced regression and progradation from the margins into the platform interior numerical forward models can augment our understanding of icehouse carbonate platform evolution by identifying the nature of the sedimentary response to individual controls they can thus contribute to improving characterization of carbonate reservoirs in icehouse platforms such as the large hydrocarbon fields in the north caspian and s e asia

flow of mantle fluids through the ductile lower crust helium isotope trends heat and mass are injected into the shallow crust when mantle fluids are able to flow through the ductile lower crust minimum 3he 4he ratios in surface fluids from the northern basin and range province western north america increase systematically from low crustal values in the east to high mantle values in the west a regional trend that correlates with the rates of active crustal deformation the highest ratios occur where the extension and shear strain rates are greatest the correspondence of helium isotope ratios and active transtensional deformation indicates a deformation enhanced permeability and that mantle fluids can penetrate the ductile lithosphere even in regions where there is no substantial magmatism superimposed on the regional trend are local high 3he 4he anomalies indicating hidden magmatic activity and or deep fluid production with locally enhanced permeability identifying zones with high resource potential particularly for geothermal energy development

boron lithium and methane isotope composition of hyperalkaline waters northern apennines italy terrestrial serpentinization or mixing with brine spring waters issuing from serpentinized ultramafic rocks of the taro ceno valleys northern apennine emilia romagna region italy were analyzed for major element trace element and dissolved gas concentrations and 11b 7li 18o h2o 2h h2o 13c ch4 and 2h ch4 isotope compositions similar to other springs worldwide that issue from serpentinites the chemical composition of the waters evolves with water rock interaction from ca hco3 through mg hco3 and ultimately to a hyperalkaline na ca oh composition most of the ca and mg hco3 springs have 11b ranging between 16 3 and 23 7 consistent with the range of low p t serpentinites very high 11b in two springs from mt prinzera pr10 39 pr01 43 can be related to isotopic fractionation during secondary phase precipitation as also inferred from 7li values in contrast to typical abiogenic isotope signatures of ch4 from serpentinized rocks dissolved ch4 from the taro ceno hyperalkaline springs has an apparent biotic thermogenic and or mixed thermogenic microbial signature with 13c ch4 ranging from 57 5 to 40 8 which is similar to that of hydrocarbons from production wells and natural seeps in adjacent hydrocarbon systems the data suggest that ch4 in the hyperalkaline springs investigated in this study may derive from organic matter of the sedimentary flysch and arenaceous formations underlying the ophiolite unit however small amounts of h2 were detected in one hyperalkaline spring pr10 but for two springs with very low ch4 concentrations pr01 and um15 the 2h value could not be measured so the occurrence of some abiotic ch4 cannot be excluded the occurrence of thermogenic ch4 in ophiolites may be a widespread phenomenon and thus the characterization of serpentinization related gases requires accurate evaluation of the regional context including a careful knowledge of the relationships with surrounding sedimentary rocks and their hydrocarbon potential

slip rate and locking depth from gps profiles across the southern dead sea transform 1 the dead sea transform is a major strike slip fault bounding the arabia plate and the sinai subplate on the basis of two gps campaign measurements 6 years apart at 17 sites distributed in israel and jordan complemented by israeli permanent stations we compute the present day deformation across the southern segment of the dead sea transform the wadi araba fault elastic locked fault modeling of fault parallel velocities provides a slip rate of 4 9 1 4 mm a and a best fit locking depth of 12 km this slip rate is slightly higher than previous results based only on israeli permanent gps stations data which are located west of the fault it is in good agreement with results based on offset geomorphologic and geologic features that average longer periods of time 10 ka to 1 ma projection in itrf2000 reference frame allows using our data combined with results published earlier to further study the kinematics between arabia nubia and sinai systematic combination of euler poles available in the literature in addition to our new set of data shows that a wide range of arabia sinai pole positions and angular velocities predict reasonable slip rate on the dead sea fault we highlight uncertainties of calculating such poles due to the small size of the blocks and their slow relative motion along a short and almost straight strand of the transform fault which lead to a large trade off between pole location and angular velocity

geological controls on natural ecosystem recovery on mine waste in southern new zealand slopes of an abandoned waste rock at wangaloa coal mine south east new zealand have naturally developed variable vegetation cover over the last 40 60 years three distinct areas of revegetation can clearly be identified dense cover patchy cover and largely unvegetated and the differences in revegetation success are directly related to the physical properties of different rock types making up the waste rock substrate the colonizing plants have become established in largely unweathered rock with essentially no soil development quartz gravel and siltstone waste rock are the two principal rock types forming substrates for revegetation the quartz gravel has clasts up to 3 cm and was derived from the coal bearing sequence siltstone was largely derived from a quaternary loess cap on the coal mine area these two substrates have similar mineral contents and this mineral material provides the low level of available nutrients however there is little difference in nutrient status or trace element load of the different substrates and differences in cohesion moisture content and proportion of quartz pebbles control revegetation success finer grained matrix has been flushed from quartz gravel waste rock by rain water leaving a dry surface armour layer of quartz pebbles this surface layer inhibits plant establishment so quartz gravel waste rock remains largely unvegetated erosion creates deep rills and steep surfaces creep downslope in contrast full vegetation cover was established on the siltstone waste rock that was cohesive and did not erode patchy revegetation was localized by siltstone in mixed quartz gravel and siltstone substrate invertebrate diversity and distribution were closely linked to the spatial patterns of revegetation the rate of revegetation and ecosystem recovery was primarily dependent on the proportion of siltstone waste rock in the last dumped truck load a quartz pebble content 15 is optimal for plant establishment

recent volcanism tectonics and plate kinematics near the junction of the african arabian and anatolian plates in the eastern mediterranean abstract in the eastern mediterranean plate convergence occurs between africa arabia and anatolia the africa arabia motion is a strike slip displacement along the dead sea fault the africa anatolia motion is taken up by subduction south of cyprus the convergence between arabia and anatolia is taken up along the east anatolian fault the analysis of the regional fault surfaces reveals the presence of two major tectonic phases that affected southeastern turkey near the junction of these three plates the older deformations are related to a n s compression the more recent movements are directed mainly westward and associated with strike slip and extension tectonics near the triple junction since 2 ma a fissure volcanism produced tholeiite followed by alkali basalt along the amanos fault the northern end segment of the dead sea fault in addition reconstruction of rigid plate kinematics between arabia africa and anatolia using recent plate motion parameters and space geodesy data suggest for the east anatolian fault a slip rate of 7 8 9 mm year the maximum finite displacement recognised for this structure being around 15 km we have obtained 1 9 ma as the maximum age for the fault formation the volcanic tectonic and kinematic data converge to propose a ca 2 ma age for the change of local tectonic regime in the junction area the structural mapping the geometry of the fractures used by the magma to reach the surface and the presence of alkali basalt of mantle source suggest that the deformation along the northern end of the dead sea transform i e the amanos fault was modified by the formation of the east anatolian fault zone in this region apparition of the east anatolian fault accommodating westward motion of the anatolian plate resulted in oblique slip tension along the amanos segment of the dead sea transform giving rise to a fissure fed mantle derived alkaline volcanism at ca 2 ma which lasted until recent times 0 4 ma

secular oscillations in the carbonate mineralogy of reef building and sediment producing organisms driven by tectonically forced shifts in seawater chemistry the primary mineralogy of oolites and early marine carbonate cements led sandberg nature 305 1983 19 22 to divide the phanerozoic eon into three intervals of aragonite seas and two intervals of calcite seas hardie geology 24 1996 279 283 has shown that these oscillations together with synchronous oscillations in the mineralogy of marine potash evaporites can be explained by secular shifts in the mg ca ratio of seawater driven by changes in spreading rates along mid ocean ridges the hardie model also predicts that high mg calcite should precipitate along with aragonite as it does in today s aragonite sea we have uncovered oscillations in the carbonate mineralogy of hypercalcifying organisms ones that have produced massive skeletons large reefs or voluminous bodies of sediment that correspond to sandberg s aragonite seas and calcite seas and that are predicted by the hardie model particular groups of corals sponges and algae appear to have been dominant reef builders only when favored by an appropriate mg ca ratio in seawater in early and middle paleozoic calcite seas calcite i reefs were dominated by calcitic tabulate heliolitid and rugose corals and calcitic stromatoporoids in contrast during the period of late paleozoic early mesozoic aragonite seas aragonite ii aragonitic groups of sponges scleractinian corals and phylloid algae as well as high mg calcitic red algae were principal reef builders during late cretaceous time at the acme of calcite ii massive rudists displaced aragonitic hermatypic corals in today s aragonite sea aragonite iii scleractinian corals are again dominant reef builders along with high mg calcitic coralline algae major sediment producing algae exhibit temporal patterns similar to those of reef builders calcitic receptaculitids flourished during calcite i whereas aragonitic dasycladaceans did not become dominant rock formers until aragonite ii during calcite ii calcitic nannoplankton formed massive coccolith chalks in warm shallow seas of the late cretaceous after the mg ca ratio of seawater had reached a very low value and calcium concentration a very high value as the mg ca ratio of seawater rose and calcium concentration fell during the cenozoic era individual coccoliths on average became less massive and encrusted cells less thickly by pliocene time during aragonite iii the prominent genus discoaster secreted only narrow rayed coccoliths that covered less than 25 of the cell surface also during aragonite iii the aragonitic green alga halimeda emerged as the dominant skeletal sediment producer in reef tracts the influence of seawater chemistry on skeletal secretion appears to have been especially strong for morphologically simple taxa that exert relatively weak control over their own calcification such groups include algae sponges corals and bryozoans morphological simplicity also permits these groups to adopt vegetative or colonial modes of growth that confer success in competition for space on reefs this linkage in addition to the basic chemical demands of hypercalcification has given the mg ca ratio of seawater strong control over the success of individual reef building taxa more generally this ratio appears to have strongly influenced evolutionary changes in the skeletal mineralogy of sponges and cheilostome bryozoans throughout their history we conclude that throughout phanerozoic time a chain of causation has extended from mid ocean ridge processes via seawater chemistry to the mineralogical and biological composition of reef communities and bioclastic carbonate deposits

the potential formation of acid mine drainage in pyrite bearing hard coal tailings under water saturated conditions an experimental approach annually an amount of approximately 13 million cubic meters of hard coal tailings must be disposed of in the german ruhr valley besides the waste of land in a densily populated region the disposal of the pyrite bearing material under atmospheric conditions may lead to the formation of acid mine drainage amd therefore alternative disposal opportunities are of increasing importance one of which being the use of tailings under water saturated conditions such as in backfilling of abandoned gravel pits or in the construction of waterways in this case the oxidation of pyrite and hence the formation of amd is controlled by the amount of oxygen dissolved in the pore water of tailings deposited under water in case the advective percolation of water is suppressed by sufficient compaction of the tailings oxygen transport can be reduced to diffusive processes which are limited by the diffusive flux of dissolved oxygen in equilibrium with the atmospheric po2 calculations of the duration of pyrite oxidation based on laboratory experiments have shown that the reduction of oxygen is mainly controlled by the content of organic substance rather than the pyrite content a fact that is supported by results from oxidation experiments with nitrate a worst case study has lead to the result that the complete oxidation of a 1 5 m layer of hard coal tailings deposited under water saturated conditions would take as much as several hundred thousand years

residence time distribution in the kirkgoz karst springs antalya turkey as a tool for contamination vulnerability assessment lumped parameter modeling of environmental tracer tritium cfcs and tritiogenic helium 3 transport in the kirkgoz karst springs antalya turkey appears to be a useful tool for assessing the vulnerability to contamination based on tritium observations between 1963 and 2000 the springs revealed a mean residence time mrt of 120 years this suggests an active transport volume of 71 billion cubic meters for the aquifer a value that is coherent with the estimated void volume of karst aquifer based on the mass of associated travertine deposits the cfc 11 and cfc 12 mrts are in agreement with tritium based mrt after correcting for excess air effect excess crustal and mantle helium flux hindered the use of tritiogenic helium 3 as a potential tracer the residence time distribution rtd indicates a groundwater transport system that is fed by recharges extending back to past several hundred years this wide rtd suggests that any recent contamination that may have entered the system could progress slowly within the entire aquifer but would be unnoticed in the early period because of the dilution effect of uncontaminated past recharge waters once the contamination is recognized it may last for many centuries ahead even if the contamination practice is stopped thus control of contaminant release to aquifer and monitoring of contaminant level in kirkgoz springs is an immediate task for the associated public health authorities

neotectonic deformation in the transition zone between the dead sea transform and the east anatolian fault zone southern turkey a palaeomagnetic study of the karasu rift volcanism in southern turkey ongoing differential impingement of arabia into the weak anatolian collisional collage resulting from subduction of the neotethyan ocean has produced one of the most complex crustal interactions along the alpine himalayan orogen several major transforms with disputed motions including the northward extension of the dead sea fault zone dsfz meet in this region to evaluate neotectonic motion on the amanos and east hatay fault zones considered to be northward extensions of the dsfz the palaeomagnetism of volcanic fields in the karasu rift between these faults has been studied remanence carriers are low ti magnetites and all except 5 of 51 basalt lavas have normal polarity morphological polarity and k ar evidence show that rift formation occurred largely during the brunhes chron with volcanism concentrated at 0 66 0 35 ma and a subsidiary episode at 0 25 0 05 forty four units of normal polarity yield a mean of d i 8 8 54 7 with inclination identical to the present day field and declination rotated clockwise by 8 8 4 0 within the 15 km wide hassa sector of the karasu rift the volcanic activity is concentrated between the amanos and east hatay faults both with left lateral motions which have rotated blocks bounded by nw se cross faults in a clockwise sense as the arabian block has moved northwestwards an average lava age of 0 5 ma yields a minimum cumulative slip rate on the system bounding faults of 0 46 cm year according with the rate deduced from the africa arabia euler vector and reduced rates of slip on the southern extension of the dsfz during plio quaternary times estimates deduced from offsets of dated lavas flows and morphological features on the amanos fault zone tectonophysics 344 2002 207 are lower 0 09 0 18 cm year probably because they are limited to surface fault breaks and do not embrace the seismogenic crust results of this study suggest that most strike slip on the dsfz is taken up by the amanos east hatay afrin fault array in southern turkey comparable estimates of quaternary slip rate are identified on other faults meeting at an unstable fff junction dsfz east anatolian fault zone karatas fault zone a deceleration in slip rate across the dsfz and its northward continuation during plio quaternary times correlates with reorganization of the tectonic regime during the last 1 3 ma including tectonic escape within anatolia establishment of the north and east anatolian fault zones bounding the anatolian collage in mid late pliocene times a contemporaneous transition from transpression to transtension and concentration of all basaltic magmatism in this region within the last 1 ma

constraints on arabian plate motion and extensional history of the red sea analysis of the geologic and geophysical data from the western and northern margin of the arabian plate combined with data from the red sea gulf of aden leads to an interpretation of arabian plate motion that supports an episodic extensional history in the red sea and gulf of aden phase 1 extension began in medial to late eocene and was caused by the nw propagation of the reoriented central indian ridge spreading center it stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures first phase extension stopped when the arabian plate terminally sutured to eurasia in the medial miocene and halted northward movement of arabia relative to africa the combined african arabian plates moved north more slowly constricting and thickening continental crust in the bitlis zagros sutures while the red sea remained technically quiescent and accumulated salt by the early pliocene continued northward movement was accommodated by lateral extrusion of large continental wedges north of the bitlis zagros sutures this allowed arabia to move northward faster than africa and reopen the red sea where phase 2 extension was expressed by seafloor spreading extension within the red sea gulf of aden rift system has been controlled by the interactions and effects of two factors 1 convergent processes between the north margin of the arabian plate and the eurasian plate to the north and 2 northwest propagation of extension associated with the medial eocene reorganization of the central indian spreading center

controls on platform scale patterns of surface sediments shallow holocene platforms bahamas isolated carbonate platforms occur throughout geological history and commonly exhibit considerable spatial variability to evaluate the controls on the nature of sediment accumulation across the expansive shallow platform tops this study systematically compares and contrasts patterns in surface sediments from several shallow 10 m holocene bahamian examples remote sensing data field observations petrographic characterization and quantitative grain size analyses reveal the spatial patterns of sediment accumulation on crooked acklins platform and the berry islands bank integration of these data with synoptic observations of waves tides and currents along with regional geochemical data provides a means to explore the factors that influence platform scale sedimentary patterns these data illustrate that the platform interiors of both crooked acklins platform and berry islands bank are blanketed with medium to coarse sand size sediment peloids are most common in the interior of crooked acklins platform whereas the berry islands bank includes more abundant composite grains in both areas very little mud is present with surface sediments averaging 2 mud comparison of these results with published data from little bahama bank great bahama bank and caicos platform suggest that contrary to previous interpretations the presence of open margins and or brisk winds are not necessary for the occurrence of a platform top with little mud although the muddy sediment fraction of the interior can be suspended by elevated wave energy wind generated current speeds in protected platform interiors are relatively low instead in parts of the platform interiors transport and winnowing of fines is enhanced greatly by tidal currents which carry suspended sediments off the shallow platforms even if shielded by islands beyond physical influences however regional geochemical compilations suggest that the bahamian tides supply highly supersaturated waters rich in dissolved oxygen to these platform interiors this exchange is interpreted to facilitate favourable conditions for calcium carbonate precipitation in the form of ooids marine cements and hardened peloids across vast expanses of the platform interiors such fundamental controls on holocene platform scale sediment dynamics are likely to have influenced carbonate systems through the geological record

sedimentology and budget of a recent carbonate mound florida keys the sedimentology of a recent carbonate mound is investigated to further our understanding of mound building communities surface and subsurface mound sediments and the overall sediment budget of mounds nine sedimentary facies of the surface of tavernier mound florida keys are described these sediments are composed of neogoniolithon halimeda porites mollusc and foraminiferal grains and lime mud muds rich in aragonite and high magnesian calcite show little mineralogical variation over the mound surface geochemical evidence suggests that the mud is mainly formed from breakdown of codiacean algae and thalassia blade epibionts production rates of the facies are established from in situ growth rate experiments and standing crop surveys annual calcium carbonate production is c 500gm 2 intermediate between reef and other bay and lagoonal environment production rates in the caribbean the internal structure of the mound studied from piston cores and sediment probes indicates that seven facies can be identified five of these can be related to the present day facies and occur in the upper part of the mound gravel mound stage the remaining two facies characterized by molluscs and aragonite rich muds occur in the lower part of the mound mud mound stage and are most similar to facies from typical florida bay mud mounds mangrove peats within the mound indicate former intertidal areas and c14 dates from these peats provide a time framework for mound sedimentation the mound appears to have formed because of an initial valley in the pleistocene surface which accumulated mud in a shallow embayment during the holocene transgression a sediment budget for the mound is presented which compares production rates from present day facies with subsurface sediment masses during the mud mound stage production rates were similar to accumulation rates and the mound was similar to the present day mounds of florida bay during the gravel mound stage 3400 yr bp present day conditions were more normal marine and the establishment of porites and neogoniolithon on the mound increased production rates 10 over accumulation rates this excess sediment is thought to be transported off the mound to the surrounding seabed models are proposed which divide carbonate mounds on the basis of internal versus external sediment supply comparisons are made with other recent and ancient mounds similarities exist between the roles of the biotic components of late palaeozoic mounds but major differences are found when structures and early diagenesis are compared

the middle eocene seeb formation of oman an investigation of acyclicity stratigraphic completeness and accumulation rates in shallow marine carbonate settings abstract the middle eocene seeb formation represents deposition on one of the earliest modern style carbonate platforms i e influenced by seagrasses and mangroves and presents an opportunity to explore controls on the preservation of cenozoic carbonate lithofacies in the study area the seeb fm is dominated by an anomalously thick approximately 250 m and uniform package of shallow marine platform interior sediments these nodular indistinctly bedded shallow subtidal sediments display no evidence for relative sea level change such as subaerial exposure features and lack the shallowing upwards cyclothems that have characterized carbonate sediments deposited in platform interior settings throughout much of the rock record particularly during greenhouse periods we conclude that this is a consequence of thorough bio retexturing of the sediment by burrowing organisms and the roots of marine vegetation which destroyed primary fabrics facies diversity evidence for cyclicity and missing time horizons such as cycle bounding exposure surfaces it seems possible that the remarkable thickness of apparently acyclic seeb fm sediment that built up may reflect increased bio disturbance of the shallow marine environment following the late cretaceous expansion of seagrasses and mangroves a similar lack of peritidal cyclothems may be common to many cenozoic shallow marine carbonate deposits missing time horizons in limestones reflecting erosion or nondeposition have been identified by some authors to explain discrepancies between low calculated accumulation rates of ancient sediments and higher rates measured in comparable modern environments however our studies of the seeb fm suggest that the significance of such missing time horizons in ancient sediments may have been overstated and that apparent differences between modern and ancient accumulation rates are a consequence of the extrapolation of unrepresentative localized high rates of modern sediment production to large platform scale areas our study reinforces the idea that modern sediment production and accumulation rates may be much lower than previously thought because they are typically measured in highly productive areas such as seagrass beds and do not take into account the highly variable nature of carbonate production storage erosion and destruction across platforms therefore far less missing time needs to be inferred for ancient sediments to account for any imbalance between modern and ancient sediment accumulation rates

origin and interactions of fluids circulating over the amik basin hatay turkey and relationships with the hydrologic geologic and tectonic settings abstract we investigated the geochemical features of the fluids circulating over the amik basin se turkey syria border which is crossed by the northern extension of the dsf dead sea fault and represents the boundary area of three tectonic plates anatolian arabian and african plates we collected 34 water samples thermal and cold from natural springs and boreholes as well as 8 gas samples bubbling and gas seepage besides the gases dissolved in the sampled waters the results show that the dissolved gas phase is a mixture of shallow atmospheric and deep components either of mantle and crustal origin coherently the sampled waters are variable mixtures of shallow and deep ground waters the latter being characterised by higher salinity and longer residence times the deep groundwaters from boreholes deeper than 1000 m have a ch 4 dominated dissolved gas phase related to the presence of hydrocarbon reservoirs the very unique tectonic setting of the area includes the presence of an ophiolitic block outcropping in the westernmost area on the african plate as well as basalts located to the north and east on the arabic plate the diffuse presence of co 2 enriched gases although diluted by the huge groundwater circulation testifies a regional degassing activity fluids circulating over the ophiolitic block are marked by h 2 dominated gases with abiogenic methane and high ph waters the measured 3 he 4 he isotopic ratios display contributions from both crustal and mantle derived sources over both sides of the dsf although the serpentinization process is generally independent from mantle type contribution the recorded helium isotopic ratios highlight variable contents of mantle derived fluids due to the absence of recent volcanism over the western side of the basin african plate we argue that co 2 rich volatiles carrying mantle type helium and enriched in heavy carbon are degassed by deep rooted regional faults rather than from volcanic sources

stochastic and deterministic controls on stratigraphic completeness and fidelity compilations of sedimentation rates determined across a large range of time spans and different sedimentary environments attest to the discontinuous nature of sedimentation and support the reasoning that hiatuses pervade sedimentary successions at multiple spatial and temporal scales the relationship between sedimentation rate and time span of observation also emphasises how stratigraphic completeness is a time span dependent concept the scaling of stratigraphic completeness with time span alludes to the likely stochastic and fractal nature of the stratigraphic record it also implies that the relationship between stratal thickness and time is inherently non linear and this has obvious implications for the way we should expect temporal processes to be recorded stratigraphically order within the stratigraphic record may arise from deterministic processes in stratigraphy most notably through astronomically influenced sedimentation intuitively a strongly ordered stratigraphic record due to the presence of cyclicity in sedimentation increases stratigraphic completeness at time spans equal to and longer than the time span of the cyclicity and minimises the non linearity between stratal thickness and time here geological data and simple modelling are used to support this supposition but these results also highlight how stochastic variability inherent in depositional processes may sensitise certain successions to missed cycles and incompleteness even in the presence of strong cyclicity this stochastic variability has the potential to mask evidence of astronomical forcing of sedimentation it is also shown how hiatuses affect the ability of a succession to faithfully record temporal processes and this is true regardless of whether hiatuses are deterministically controlled or random or indeed whether a succession is considered complete or not consequently stratigraphic completeness and stratigraphic fidelity are not synonymous terms

crustal thickness of turkey determined by receiver function abstract two hundred and sixty seven teleseismic events with a moment magnitude greater than 5 5 which occurred between january 2005 and october 2010 were analyzed to determine the moho depth variation beneath turkey by using the receiver function rf technique the rf technique was applied to 120 broadband seismic stations which were already deployed in the area permanently by the kandilli observatory and earthquake research institute koeri and the disaster and emergency management presidency afad the rfs were stacked considering back azimuth slowness and waveform similarities to enhance the signal noise ratio the genetic algorithm ga was used to obtain both 1 d shear wave speed model and the moho depth beneath each seismic station a data set consisting of 112 shear speed models derived from rfs revealed the crustal structure of turkey for imaging several 2 d profiles of depth migrated rfs were constructed to delineate the fine crustal structure the moho discontinuity is clearly seen on all profiles and the mid crustal velocity discontinuity within the crust is observed in some profiles the depth of the moho varies between 24 and 48 km the thinnest crustal thickness is located on the coast of western turkey and the deepest moho boundary is observed in eastern turkey the shear wave velocities vary between 4 0 km s and 4 5 km s in the uppermost mantle beneath turkey

geochemical distribution and removal of as fe mn and al in a surface water system affected by acid mine drainage at a coalfield in southwestern china the chemical characteristics formation and natural attenuation of pollutants in the coal acid mine drainage amd at xingren coalfield southwest china are discussed in this paper based on the results of a geochemical investigation as well as geological and hydrogeological background information the chemical composition of the amd is controlled by the dissolution of sulfide minerals in the coal seam the initial composition of the groundwater and the water rock interaction the amd is characterized by high sulfate concentrations high levels of dissolved metals fe al mn etc and low ph values ca2 and so42 are the dominant cation and anion in the amd respectively while ca2 and hco3 are present at significant levels in background water and surface water after the drainage leaves the mine site the ph and alkalinity increase asymptotically with the distance along the flow path while concentrations of sulfate ferrous iron aluminum and manganese are typically controlled by the deposition of secondary minerals low concentrations of as and other pollutants in the surface waters of the xingren coalfield could be due to relatively low quantities being released from coal seams to adsorption and coprecipitation on secondary minerals in stream sediments and to dilution by unpolluted surface recharge although as is not the most serious water quality problem in the xingren region at present it is still a potential environmental problem

regional and temporal variations in co2 3he 3he 4he and δ13c along the north anatolian fault zone turkey abstract new he and c relative abundance isotope and concentration results from nine geothermal locations situated along an 800 km transect of the north anatolian fault zone nafz turkey that were monitored during the period november 2001 november 2004 are reported the geothermal waters were collected every 3 6 months to study possible links between temporal geochemical variations and seismic activity along the nafz at the nine sample locations the he isotope ratios range from 0 24 to 2 3 r a 13 c values range from 4 5 to 5 8 and co 2 3 he ratios range from 5 10 9 to 5 10 14 the following geochemical observations are noted 1 the highest 3 he 4 he ratios are found near the galatean volcanic region in the central section of the nafz 2 at each of the nine sample locations the 3 he 4 he ratios are generally constant however co 2 3 he ratios and he contents both show one order of magnitude variability and 13 c values show up to 4 variability and 3 at all locations except resadiye 13 c values show positive correlations with co 2 contents the results indicate that at least three processes are necessary to account for the geochemical variations 1 binary mixing between crustal and mantle derived volatiles can explain the general characteristics of 3 he 4 he ratios 13 c values and co 2 3 he ratios at the nine sample locations 2 preferential degassing of he from the geothermal waters is responsible for variations in co 2 3 he values and he contents at each sample location and 3 co 2 dissolution followed by calcite precipitation is responsible for variations in co 2 contents and 13 c values at most locations for each of the geochemical parameters anomalies are defined in the temporal record by values that fall outside two standard deviations of average values at each specific location geochemical anomalies that may be related to seismic activity are recorded on june 28 2004 at yalova where a m 4 2 earthquake occurred 43 days earlier at 15 km distance from the sample location and on april 7 2003 at efteni where a m 4 0 earthquake occurred 44 days later at a distance of 12 km at both locations the sampling periods containing geochemical anomalies were preceded by an increase in m 3 earthquakes occurring within 60 days and less than 40 km distance

rate of diffuse carbon dioxide earth degassing estimated from carbon balance of regional aquifers the case of central apennine italy central italy is characterized by an anomalous flux of deeply derived co2 in the western tyrrhenian sector of central italy co2 degassing occurs mainly from focused emissions vents and strong diffuse degassing and thermal springs whereas in the eastern apennine area deep co2 is dissolved in cold groundwaters of regional aquifers hosted by mesozoic carbonate evaporite formations influx of deep co2 into 12 carbonate aquifers 12 500 km2 of the central apennine is computed through a carbon mass balance that couples aquifer geochemistry with isotopic and hydrogeological data mass balance calculations estimate that 6 5 1010 mol yr 1 of inorganic carbon are dissolved in the studied aquifers approximately 23 of this amount derives from biological sources active during the infiltration of the recharge waters 36 comes from carbonate dissolution while 41 is representative of deep carbon sources characterized by a common isotopic signature 13c 3 the calculated deep co2 influx rate ranges from 105 to 107 mol yr 1 km 2 increasing regionally from east to west in the study area

the carbonate chemistry of grand bahama bank waters after 18 years another look major features of the chemistry of northern grand bahama bank waters found in 1981 were similar to those found by broecker and takahashi in 1962 and 1963 measured variations in salinity and extent of caco3 removal are close to the same our findings indicate a more complex salinity distribution on the northern banks probably resulting from transport of high salinity waters from the south and higher pco2 values in the high salinity waters inorganic 14co2 measurements made in this study can be used to calculate very approximate residence times of water on the bank there is general agreement with the values previously determined by broecker and takahashi ship aerial and satellite observations indicate that whitings are not randomly distributed over the bank they form a halo around the northern and western flanks of the high salinity waters s greater than 40 the rate of caco3 removal is about 1 5 times faster in the waters where the whitings are common than in the high salinity waters even though our analytic precision was over 80 times greater than the change predicted in alkalinity if whitings precipitate directly from seawater no differences could be found between whiting and adjacent waters in our opinion the major features responsible for creating whitings controlling their distribution and determining caco3 removal rates on the grand bahama bank remain largely unresolved

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

variation in noble gas isotopic composition of gas samples from the aegean arc greece abstract in contrast to most other arcs with oceanic plate subduction the aegean arc is characterized by continent continent subduction noble gas abundances and isotopic compositions of 45 gas samples have been determined from 6 volcanoes along the arc 2 islands in the back arc region and 7 sites in the surrounding areas the 3he 4he ratios of the samples ranged from 0 027ra to 6 2ra ra denotes the atmospheric 3he 4he ratio of 1 4 10 6 demonstrating that even the maximum 3he 4he ratio in the region is significantly lower than the maximum ratios of most oceanic subduction systems which are equal to the morb value of 8 1 ra regional variations in the 3he 4he ratio were observed both along and across the arc the maximum 3he 4he ratio was obtained from nisyros volcano located in the eastern end of the arc and the ratio decreased westward possibly reflecting the difference in potential degree of crustal assimilation or the present magmatic activity in each volcano across the volcanic arc the 3he 4he ratio decreased with an increasing distance from the arc front reaching a low ratio of 0 063ra in macedonia which suggested a major contribution of radiogenic helium derived from the continental crust at nisyros a temporal increase in 3he 4he ratio due to ascending subsurface magma was observed after the seismic crisis of 1995 1998 and mantle neon was possibly detected the maximum 3he 4he ratio 6 2ra in the aegean region which is significantly lower than the morb value is not probably due to crustal assimilation at shallow depth or addition of slab derived helium to morb like mantle wedge but inherent characteristics of the subcontinental lithospheric mantle sclm beneath the aegean arc

geochemical behavior of arsenic in reducing sulfidic sediments of reservoir contaminated by acid mine drainage the sediment from an acid mine drainage affected reservoir of guizhou province of china has the iron and arsenic concentration of about 400 and 2 6 g kg respectively sediment cores were collected and were used to study the arsenic behavior in the seriously acidified reservoir from the viewpoint of chemical thermodynamics the limestone neutralization and ferric iron hydrolysis regulated the porewater ph from about 2 9 5 8 the reductive dissolution of as fe rich hydr oxides under the mild acidic conditions was the main mechanism for the release of absorbed arsenic into porewater the maximum concentrations of iron sulfate and arsenic reached to about 2 800 9 000 and 1 mg l respectively arsenic speciation transformation and hydrous ferric oxide hfo crystallization enhanced the arsenic mobility in sediment in addition the iron sulfide minerals diagenesis could play a role in removing the dissolved arsenic from porewater the actual distribution of arsenic concentration in porewater was well simulated using the model of surface complexation of arsenic to hfo although arsenic concentration in porewater could be above 100 times higher than that of reservoir water it was not easy to release into the reservoir water through diffusion because the shallow sediment had relatively strong arsenic adsorption capacity and new hfo could be generated continuously at the sediment water interface

modelling the effect of chemical heterogeneity on acidification and solute leaching in overburden mine spoils abstract the generation of acid mine drainage from overburden spoil piles at open pit lignite mines is impacting the quality of groundwater and surface water bodies in large parts of the lusatian mining area in germany values of ph as low as 1 have been observed in the groundwater after decommissioning mine pits are generally converted to lakes which may also be acidic owing to the acidic groundwater discharge the acidic effluent is generated by sulphide oxidation in the unsaturated zone of the spoil pile which generally extends to large depths as a result of dewatering the long term evolution of the acidification is still largely unknown our research focuses on the effects of physical and chemical heterogeneity caused by mixing of soil materials that may have already been oxidized to different degrees during the deposition of the spoil pile processes considered include variably saturated groundwater flow oxygen diffusion in the soil gas kinetic pyrite oxidation and acidic effluent generation advective dispersive transport of the aqueous components equilibrium geochemical reactions between the chemical components and the soil minerals and possible buffering and acid neutralization several existing numerical codes were coupled to represent the complete set of processes simulations were carried out in one and two dimensions using representative characteristics of mine spoil piles with the two dimensional representation being based on spatially heterogeneous random fields of hydraulic conductivity and sulphide mineral fractions results show the long term evolution of the oxidation front the mass flux of oxidation products and the effects of system heterogeneity under conditions of constant flow the system is found to return to neutral conditions over a time period on the order of several decades further work including sensitivity analyses with respect to the controlling parameters and model calibration using site specific field data will be necessary to obtain a full understanding of the complex interacting mechanisms the simulation approach shows promise as a potentially useful tool for predicting the effects of sulphide oxidation on the water quality of pit lakes

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

evidence for 830 years of seismic quiescence from palaeoseismology archaeoseismology and historical seismicity along the dead sea fault in syria an edited version of this paper was published in earth and planetary science letters by elsevier science elsevier science retains the copyright to this paper copyright 2003 see also http dx doi org 10 1016 s0012 821x 03 00144 4 http atlas geo cornell edu deadsea publications meghraoui2003 epsl htm

sequence development on a sediment starved low accommodation epeiric carbonate ramp silurian wabash platform usa mid continent during icehouse to greenhouse transition abstract twelve cored wells through the silurian section of the wabash platform indiana u s a and 2 non cored basinal wells with cuttings were studied to define the sequence stratigraphy of a sediment starved ramp within a low latitude epeiric sea during the latest ordovician icehouse to silurian greenhouse transition the wabash platform approximately 200 000 km2 area was bounded to the north by the michigan basin to the east by the appalachian foreland basin and passed to the southwest into the vincennes basin which was open to the ocean facies developed include platform fringing buildups stromatactis wackestone core stromatoporoid skeletal wackestone caps and crinoidal rudstone packstone flank facies and non buildup crinoid grainstone packstone sheets shoals skeletal wackestone variably cherty between fair weather and storm wave base deep lagoon and deep ramp and carbonate mudstone clean to argillaceous sub storm wave base deep lagoon and deep ramp basin the eleven sequences 2 m to 30 m thick and 1 to 4 m y durations average 2 5 m y generally can be correlated to global sea level cycles the lower three sequences are disconformity bounded reflecting moderate ice sheets but the others are relatively conformable the most easily mapped regional surfaces are the transgressive surfaces because the correlative conformities are cryptic the wide well spacing prevented mapping of lowstand system tracts the transgressive systems tracts are upward deepening upward fining carbonate units that become more argillaceous and silty upward the highstand systems tracts are upward coarsening carbonate mudstone to wackestone packstone and rare grainstone barrier bank complexes and isolated buildups aggraded during deposition of the upper 4 sequences to form a discontinuous raised rim 40 m relief to the ramp while the interior of the platform remained sediment starved subsidence rates in the basin were very low 0 6 to 1 2 cm k y but the low platform accumulation rates 0 2 cm k y to 0 8 cm k y prevented the seafloor from building to sea level in all but the lower three sequences and later over barrier banks accumulation rates 2 cm k y parasequence development in high accommodation settings elsewhere in the silurian in north america records transition from moderate ice sheets to an ice free world this is weakly expressed on the wabash platform due to the dominantly deeper subtidal setting the remarkably low sedimentation rates resulted from the epeiric sea being isolated from the open ocean and they likely are typical of the large epeiric seas of the paleozoic

helium isotope variations in turkey relationship to tectonics volcanism and recent seismic activities the distribution of helium isotope ratios in the various tectonic provinces of turkey is examined through a synthesis of previously published data and the results of a recent survey along the north anatolian fault zone nafz following the catastrophic 1999 earthquakes the r ra values where r sample 3he 4he and ra air 3he 4he cover a wide range from 0 05 to 7 87 and the mantle derived helium is clearly identified in most locations the mantle derived component is high 50 of total he in a regions of central and eastern anatolia both of which are associated with historically active volcanoes and b the seismically active west to central segment of nafz while the mantle contribution reaches a maximum at nemrut volcano in eastern anatolia a region of dominantly compressional tectonics and with moderate enthalpy geothermal fields it is relatively low 50 in the western anatolian extensional province even though this region has the highest geothermal potential the average 3he enthalpy ratios estimated for the different provinces suggest lithospheric stretching and rise of the geotherm as the major mechanism of high heat flow yet limited intrusive activity in western anatolia is suggested as the reason for the comparatively low he additions and consequently low 1 7 106 atoms j 3he enthalpy ratios a more extensive magmatic activity appears to be responsible for the greater input of both heat and helium in eastern and central anatolia with intra province 3he enthalpy variations from 3 1 106 atoms j in eastern to 0 25 106 atoms j in central anatolia reflecting the ageing of hydro magmatic systems the relatively high 3he concentrations in low enthalpy waters of northern anatolia 2 8 106 atoms j are particularly significant since there is no evidence of volcanic activity associated with the strike slip motion along the seismically active segment of nafz continuous monitoring of he isotope compositions along nafz should lead to a better understanding of this apparent anomaly as well as the relationship if any between he isotope variations and seismic activities in this region

dissolved helium isotope ratios in ground waters a new technique based on gas water re equilibration and its application to stromboli volcanic system here a new technique for the determination of dissolved he isotope ratios in ground waters is presented this method is based on the extraction and subsequent equilibrium of dissolved gases in an added host gas phase ultra pure n2 is placed in glass flasks 250 cc containing water samples that were hermetically sealed after their collection after shaking in an ultrasonic bath for 10 min an aliquot of the separated gas phase was removed from the flask for ms analysis 3he 4he ratios are measured by using a modified double collector mass spectrometer vg 5400 tft helium and ne concentrations are calculated by comparing the partial pressures of masses 4 and 20 of the samples with those of the air standard measured by a quadrupole mass spectrometer qms vg quartz using he and ne equilibrium partitioning coefficients it is possible to calculate the amount of gas originally dissolved in the water the technique was tested on both air saturated waters asw and thermal waters from stromboli aeolian islands south italy the results of which confirmed good reproducibility 5 and accuracy 3 of the data the method was then applied to three thermal water samples collected from the same volcanic area and the results compared with those of a fumarolic and a soil gas the isotope ratios for dissolved he gave values of 4 06 4 23 ra which are significantly higher than those previously reported in the literature 3 0 3 5 and 2 9 ra and that measured at the fumarole 3 09 ra suggesting a newer and higher isotopic signature for the volcanic system the proposed method appears to be a useful tool in the determination of 3he 4he ratios in ground water systems especially when free gases are not available or are dangerous to collect

the geochemistry of rare earth elements ree in acid mine drainage from the sitai coal mine shanxi province north china abstract in this paper geochemical characteristics of rare earth elements ree in acid mine drainage amd from the sitai coal mine of shanxi province north china were investigated by determining concentrations of dissolved rees and major solutes in the amd samples concentrations of rees in the amd precipitate samples and country rock samples mudstone and coal and modeling rees species in the amd the results show that amd in the sitai coal mine have high rees and so42 concentrations in comparison with several terrestrial waters worldwide the ree speciation modeling indicates that sulfate complexes lnso4 60 and free metal species ln3 20 40 are dominant rees species in the amd amd of the sitai coal mine also shows a middle ree enriched nasc north american shale composite normalized pattern the authors suggest that both ree sulfates lnso4 in the amd and country rock of coal measures are possible reasons for middle ree enriched nasc normalized pattern of the sitai coal mine amd further work on the amd precipitates is needed to obtain more information on the origin of the middle ree enriched nasc normalized patterns

geochemical modeling of coal mine drainage summit county ohio geochemical modeling was used to investigate downstream changes in coal mine drainage at silver creek metro park summit county ohio a simple mixing model identified the components that are undergoing conservative transport cl po43 ca2 k mg2 and na and those undergoing reactive transport do hco3 so42 fe2 mn2 and si fe2 is removed by precipitation of amorphous iron hydroxide mn2 are removed along with fe2 by adsorption onto surfaces of iron hydroxides do increases downstream due to absorption from the atmosphere the hco3 concentration increases downstream as a result of oxidation of organic material the rate of fe2 removal from the mine drainage was estimated from the linear relationship between fe 2 concentration and downstream distance to be 0 126 mg s results of this study can be used to improve the design of aerobic wetlands used to treat acid mine drainage