growth patterns and implications of complex dendrites in calcite travertines from lýsuholl snaefellsnes iceland calcite dendrite crystals are important but poorly understood components of calcite travertine that forms around many hot springs the l suholl hot spring deposits located in western iceland are formed primarily of siliceous sinters that were precipitated around numerous springs that are now inactive calcite travertine formed around the vent and on the discharge apron of one of the springs at the northern edge of the area the travertine is formed largely of two types i and ii of complex calcite dendrite crystals up to 1 cm high that grew through the gradual addition of trilete sub crystals the morphology of the dendrite crystals was controlled by flow direction and the competition for growth space with neighbouring crystals densely crowded dendrites with limited branching characterize the rimstone dams whereas widely spaced dendrites with open branching are found in the pools many dendrite bushes in the pools nucleated around plant stems growth of the dendrite crystals was seasonal and incremental calcite precipitation was driven by rapid co2 degassing of co2 rich spring waters during the spring and summer during winter when snow covered the ground and temperatures were low opal a precipitated on the exposed surfaces of the dendrites segmentation of dendrite branches by discontinuities coated with opal a and overgrowth development around sub crystals resulted from this seasonal growth cycle the calcite dendrite crystals in the l suholl travertine differ in morphology from those at other hot springs such as those at lake bogoria kenya and waikite in new zealand comparison with the calcite dendrite crystals found at those sites shows that dendrite morphology is site specific and probably controlled by carbonate saturation levels that in turn are controlled by the rate of co2 degassing and location in the spring outflow system

comparison of the quaternary travertine sites in the denizli extensional basin based on their depositional and geochemical data abstract in the denizli basin turkey located in the western anatolian extensional province travertine and tufa deposition has been an ongoing process for at least 600 000 years travertine bodies which are 30 to 75 m thick and each covers areas of 1 to 34 km2 are up to 1 km3 in volume today spring waters in this area have temperatures of 19 to 57 c are of the ca mg hco3 so4 type in the pamukkale kelkaya and pinarbasi areas and the ca mg so4 hco3 type at cukurbag thermal waters along the northern margin of the basin are generally hotter than those in the east southeast and south the 18o and d values of the spring waters indicate a meteoric origin the average temperatures of the hydrothermal systems in the denizli basin appear to have decreased from pleistocene to holocene travertine which formed from the hotter water is more widespread than the tufa that formed in the cooler spring waters deposition of the travertine which formed largely on slopes in depressions and along fissure ridges mostly on northern basin margins was controlled by the interplay between various intrinsic and extrinsic parameters the travertines are formed largely of calcite with only minor amounts of aragonite in some of the vertically banded crystalline crust raft and pisoid travertines found in some of the northern sites the aragonitic samples rich in sr are typically found around the spring orifices and along the central axis of the fissure ridges the stable isotope values of the travertine found in the northwest and southeast parts of the basin are different the 13c values of the northern travertine deposits are more positive 3 7 to 11 7 vpbd than those found in the south southeast areas 4 to 5 8 vpdb in contrast the travertine and tufa in the southeastern areas have higher 18o values 15 2 to 7 8 vpdb than those of the northern areas 16 6 to 4 8 vpdb available evidence indicates that spring activity and associated travertine precipitation in the denizli basin were controlled largely by tectonic activity rather than by climatic conditions

compilation of non annually resolved holocene proxy climate records stacked holocene peatland palaeo water table reconstructions from northern britain abstract the number and range of holocene palaeoclimate reconstructions from various regions of the world have increased dramatically over the last decade the data density for many regions and proxies now offers the potential of robust regional scale reconstructions that avoid the problems of records from individual sites and improve communication between palaeoclimate subdisciplines and climate modellers however there are problems with chronological uncertainties and quantification of proxies which make compilation of multiple records difficult here we explore a stacking and tuning approach to the derivation of regional records from peatland climate proxies to test its applicability to non annually resolved terrestrial records twelve individual records from northern britain based on water table reconstructions from testate amoebae analysis were divided into four regions records were detrended normalised and compared within regions to identify clear correlative events the original chronologies of the records were tuned using both these events and independent age markers the stacked record for northern britain indicates pronounced changes to wet conditions at 3600 2760 and 1600 cal yr bp with more minor changes at 3060 2050 1260 860 550 and 260 cal yr bp the main wet phases are highly correlated with mid european lake highstands wider north atlantic climate change inferred from ocean and ice core records and solar variability tuning and stacking of non annual terrestrial palaeoclimate records is a new approach to the compilation and reconciliation of individual records within coherent climatic regions and provides a tool for upscaling of palaeoclimate records for climate model data comparisons

microbe mineral interactions early carbonate precipitation in a hypersaline lake eleuthera island bahamas microbialites benthic microbial carbonate deposits were discovered in a hypersaline alkaline lake on eleuthera island bahamas from the edge towards the centre of the lake four main zones of precipitation could be distinguished 1 millimetre sized clumps of mg calcite on a thin microbial mat 2 thicker and continuous carbonate crusts with columnar morphologies 3 isolated patches of carbonate crust separated by a dark non calcified gelatinous mat and 4 a dark microbial mat without precipitation in thin section the precipitate displayed a micropeloidal structure characterized by micritic micropeloids strong autofluorescence surrounded by microspar and spar cement no fluorescence observations using scanning electron microscopy sem equipped with a cryotransfer system indicate that micrite nucleation is initiated within a polymer biofilm that embeds microbial communities these extracellular polymeric substances eps are progressively replaced with high mg calcite discontinuous eps calcification generates a micropeloidal structure of the micrite possibly resulting from the presence of clusters of coccoid or remnants of filamentous bacteria at high magnification the microstructure of the initial precipitate consists of 200 500 nm spheres no precipitation is observed in or on the sheaths of cyanobacteria and only a negligible amount of precipitation is directly associated with the well organized and active filamentous cyanobacteria in deeper layers of the mat indicating that carbonate precipitation is not associated with co2 uptake during photosynthesis instead the precipitation occurs at the uppermost layer of the mat which is composed of eps empty filamentous bacteria and coccoids gloeocapsa spp two dimensional mapping of sulphate reduction shows high activity in close association with the carbonate precipitate at the top of the microbial mat in combination these findings suggest that net precipitation of calcium carbonate results from a temporal and spatial decoupling of the various microbial metabolic processes responsible for caco3 precipitation and dissolution theoretically partial degradation of eps by aerobic heterotrophs or uv fuels sulphate reducing activity which increases alkalinity in microdomains inducing caco3 precipitation this degradation could also be responsible for eps decarboxylation which eliminates ca 2 binding capacity of the eps and releases ca 2 ions that were originally bound by carboxyl groups at the end of these processes the eps biofilm is calcified and exhibits a micritic micropeloidal structure the eps free precipitate subsequently serves as a substrate for physico chemical precipitation of spar cement from the alkaline water of the lake the micropeloidal structure has an intimate mixture of

controls on microbial activity and tidal flat evolution in shark bay western australia microbial deposits at shark bay constitute a diverse living microbial carbonate system developed in a semi arid highly evaporative marine setting three tidal flats located in different embayments within the world heritage area were investigated in order to compare microbial deposits and their holocene evolution the stressing conditions in the intertidal subtidal environment have produced a microbial ecosystem that is trapping binding and biologically inducing caco3 precipitation producing laminated stromatolites tufted smooth and colloform non laminated thrombolitic forms pustular and cryptomicrobial non laminated forms microbial pavement a general shallowing upwards sedimentary cycle was recognized and correlated with holocene sea level variations where microbial deposits constitute the younger 2360 years bp and shallower sedimentary veneer in addition sediments have been documented with evidence of exposure during the holocene from 1040 to 940 14c years bp when sea level was apparently lower than present filamentous bacteria constitute the dominant group in the blister tufted and smooth mat types and coccus bacteria dominate the pustular colloform and microbial pavement deposit types in the subtidal environment within colloform and pavement structures microbial communities coexist with organisms such as bivalves serpulids diatoms green algae acetabularia crustaceans foraminifera and micro gastropods which are responsible for exoskeleton supply and extensive bioturbation the internal fabric of the microbial deposits is laminated sub laminar scalloped irregular or clotted depending on the amount of fine grained carbonate and the natural ability of microbial communities to trap and bind particles or induce carbonate precipitation nilemah tidal flat contains the thickest 1 3 m and best developed microbial sedimentary system its deposition pre dated the rocky point and garden point tidal flats with the most positive isotope values for 13c and 18o reflecting strong microbial activity in a highly evaporative environment there is an evolutionary series preserved within the tidal flats reflecting relative ages and degree of salinity elevation

novel applications of fluid inclusions and isotope geochemistry in unravelling the genesis of fossil travertine systems the denizli basin is a fault bounded neogene quaternary depression located in the western anatolian extensional province western turkey the basin is a unique geological site with abundant active and fossil quaternary travertine and tufa deposits fluid inclusion microthermometry and isotopic analysis were applied to study the genesis of the ballk fossil travertine deposits located in the south eastern part of the basin microthermometry on fluid inclusions indicates that the main travertine precipitating and cementing fluids are characterized by low salinity 07wt nacl equivalent and variable temperatures that cluster at 50 degrees c and ca 100 degrees c fluids of meteoric origin have been heated by migration to the deeper subsurface possibly in a local high geothermal gradient setting a later uncommon cementation phase is related to a fluid with a significantly higher salinity 255 to 260wt bulk the fluid obtained its salinity by interaction with late triassic evaporite layers strontium isotopes indicate that the parent carbonate source rock of the different travertine precipitates is very likely to be the triassic limestone of the lycian nappes carbon isotopes suggest that the parent co2 gas originated from thermal decarbonation of the lycian limestones with minor contributions of magmatic degassing and organic soil co2 oxygen isotopes confirm the meteoric origin of the fluids and indicate disequilibrium precipitation because of evaporation and degassing results were integrated within the available geological data of the denizli basin in a generalized travertine precipitation model which enhanced the understanding of fossil travertine systems the study highlights the novel application of fluid inclusion research in unravelling the genesis of continental carbonates and provides several recommendations for hydrocarbon exploration in travertine bearing sedimentary basins the findings suggest that travertine bodies and their parent carbonate source rocks have the potential to constitute interesting subsurface hydrocarbon reservoirs

interpreting luminescence data from a portable osl reader three case studies in fluvial settings optically stimulated luminescence osl is a technique that has been applied from the mid 1980s mainly for sediment dating the osl technique is based on sample stimulation by light to determine the luminescence signal that is stored in the crystal lattices of sediment grains after deposition burial by later sediment and subsequent exposure to ionizing radiation from radioactive elements in the surrounding sediment in such sediment dating two parameters are required the equivalent dose i e the luminescence signal stored in the grains and the dose rate i e the ionizing energy from and radiation emitted by naturally occurring radioisotopes in the deposit plus the effects of cosmic radiation in this research the osl technique is not used for dating the study goal is to analyse only the luminescence signals the total photon counts in polymineral samples obtained after light stimulation in the blue blsl and infrared irsl wavelengths using a portable osl reader designed and built at the scottish universities environmental research centre suerc three fluvial case studies from cambodia australia and mexico are used to illustrate the geomorphological interpretations possible with the portable osl reader data from sediments resulting from a range of different depositional processes the case studies show that aspects of sediment s transport and depositional processes can be inferred from the portable osl reader data providing valuable insights into geomorphological history copyright 2010 john wiley sons ltd

comparative study of the pleistocene cakmak quarry denizli basin turkey and modern mammoth hot springs deposits yellowstone national park usa this study compares and contrasts the travertine depositional facies of two of the largest sites of travertine formation located in very different geological contexts i e the modern mammoth hot spring mhs system in the active volcanic complex of yellowstone national park usa and the pleistocene cakmak quarry a well exposed example of the ballik travertines in the extensional denizli basin turkey new 2d to 3d facies maps of both travertine systems combined with microscopy assist in proposing an integrated spring depositional model based on the existing mhs facies model understanding general controls on meter to kilometer scale travertine deposit architecture and its preservation and provide quantitative estimates of facies spatial coverage and slope using gis the comparison resulted in the distinction of eight facies grouped in five downstream facies zones from vent to distal slope notwithstanding the different geological context of both travertine systems observations show that several of the facies are strikingly comparable draping apron and channel facies top slope pond facies crystalline proximal slope facies and distal slope facies whereas other facies do not have a precise exposed equivalent vent facies pavement apron and channel facies extended pond facies and phyto proximal slope facies combining observations of active springs at mhs with the cakmak vertical travertine quarry exposures demonstrates that lateral and vertical facies transitions are a sensitive record of changes in the spring dynamics flow intensity and paths that become well preserved in the geological record and can be recognized as prograding aggrading retrograding trends or erosive surfaces traceable over tens to hundreds of meters quantification of facies specific coverage at mhs shows that proximal and distal slope facies deposits cover as much as 90 of the total mapped surface area in addition only 7 of the surface is found to be marked by a waterfilm related to an active flowing spring slope statistics reveal that strong slope breaks can often be related to transgressive apron and channel facies belts and that variable but steep slopes up to 40 are dominated by proximal slope facies in agreement with the cakmak exposures integrating travertine facies and architecture of deposits formed in distinct geological contexts can improve the prediction of general spring facies distributions and controls in other modern and ancient subsurface travertine systems

modelling the impact of depositional and diagenetic processes on reservoir properties of the crystal shrub limestones in the pre salt barra velha formation santos basin brazil abstract the cretaceous barra velha formation pre salt of the santos basin brazil includes lacustrine crystal shrub limestones which represent important hydrocarbon reservoirs neither single nor multi phase flow behaviour of these unusual fabrics has been modelled to date here we quantify the impact of depositional and diagenetic processes on selected reservoir properties of the crystal shrub limestones using highly flexible 3d synthetic pore scale models that can explore parameter space rather than producing models validated to actual reservoir properties this seeks to establish trends and identify emergent clustering behaviour shrubby aggregates nucleate from a surface to form upward and outward growing branching fascicular optical calcite crystal fans that are diverse in size and form the model allows exploration of the impact of primary growth parameters number of bifurcations or branching shrub height angle of cone or fan inflation as well as subsequent inter shrub cementation and dissolution on resultant porosity permeability and multiphase flow simulations show that depositional parameters as well as two major diagenetic processes cementation and dissolution control porosity and permeability in some cases these trends diverge considerably from widely referenced kozeny carman kc porosity permeability relationships the angle of shrub inflation produces data clusters that traverse kc bands by contrast the number of bifurcations and the degree of dissolution follows kc trends so providing guidance for potential rock type subdivision of similar lithologies on this basis we propose that the crystal shrub limestones in the barra velha formation can be subdivided into three broad petrophysical reservoir rock types based on the degree of shrubby aggregate bifurcation and extent of dissolution the trends explored here can be used to link conceptual and process based geological models to data so enabling more accurate prediction and upscaling of heterogeneous reservoir properties and their reservoir scale distribution

palaeoseismicity and pottery investigating earthquake and archaeological chronologies on the hajiarab alluvial fan iran for millennia humans have lived in locations that are highly vulnerable to large earthquakes often out of strategic or cultural necessity and or the proximity of these locations to resources necessary for survival despite the often catastrophic effects when large earthquakes occur recent history reveals that human nature is to rebuild rather than relocate implying that seismic activity is not a sufficient deterrent of population growth in tectonically vulnerable areas in order to investigate whether this was the case for ancient civilisations and thus perhaps a fundamental tenet of human behaviour a palaeo earthquake history was developed for the active cheskin and ipak faults in northwestern iran and compared with the well resolved archaeological history of the nearby sagzabad cluster settlements of zagheh 7170 6300 bp ghabristan 6215 4950 bp and sagzabad 4050 2350 bp combining new geologic geomorphic and chronologic datasets revealed the presence of a fault propagated anticline formed by large mw 6 5 7 0 earthquakes on a blind thrust fault that projects to seismogenic depth directly beneath the sagzabad cluster settlement sites large earthquakes with a return period of 90 probability under most faulting scenarios that the energy release from these earthquakes would have been of sufficient magnitude to generate peak horizontal acceleration pha values at the sagzabad cluster in excess of likely threshold values for complete settlement destruction poisson modelling assuming a time displacement repeating model for earthquake recurrence indicates a 66 42 probability of one two earthquakes that would generate pha 0 25 g occurring during occupation of zagheh a 79 55 probability for ghabristan and an 88 65 probability for sagzabad despite the near certainty that the residents of these holocene settlements experienced large destructive earthquakes the near continuous history of occupation at this area suggests that early humans were not apt to relocate in response to earthquake activity environmental e g alluviation stream channel avulsion climate change cultural and or political factors may have been more important drivers of settlement shifts and abandonment at the sagzabad cluster of iran

the role of magnesium in the crystallization of calcite and aragonite in a porous medium abstract morphological development of calcite crystals is related to supersaturation conditions during growth crystallization of calcium carbonate calcite and aragonite as well as mg calcite was studied under controlled supersaturation conditions by the counter diffusion of ca2 and co32 ions through a porous transport medium a column of silica gel under our experimental conditions where ion transport is constrained to be diffusion controlled nucleation and growth take place under conditions of high supersaturation the actual threshold value of the supersaturation depending on the supersaturation gradient in the pure caco3 system calcite grows at lower supersaturation than aragonite the calcite develops relatively simple rhombohedra whil the aragonite grows as spherulites presence of mg2 in the interstitial fluid inhibits nucleation increasing the threshold supersaturation at which crystallization begins the resulting mg calcite crystals show a range of morphologies depending on the mg content and the supersaturation at the point of crystallization at high values of supersaturation up to 15 mol mgco3 is incorporated into the calcite and the crystals form spheres at lower supersaturations mg content decreases and morphologies change progressively through a well defined and reproducible sequence from spheres to dumbbell like forms to wheat sheaf like bundles and eventually single crystals with steep rhombohedral faces the crystals are compositionally zoned showing both sector and oscillatory zoning the compositional evol tion is related to the supersaturation and interface roughness during crystal growth

coexisting active travertines and tufas in the southeastern border of the puna plateau abstract the terma los hornos is an active hydrothermal system located in the southeastern border of the andean puna plateau in catamarca province northwest argentina it exhibits a complete range from high to low temperature quaternary carbonate products still actively forming travertines and tufas can be considered lithological end members within the depositional system but the lack of clear boundaries has generated confusion when trying to distinguish them in the fossil record in the terma los hornos a continuum between both extremes is recorded through a transition of different morphologies and dominant but non diagnostic fabrics among which we recognize a variety of crystalline crusts shrubs spheroidal particles encrusted bubbles and reeds lithoclastic grumulous micritic and silty sandy carbonates these were grouped in the following depositional subsystems 1 vents and pinnacles 2 mound apron 3 terraced slope 4 steep slopes and 5 flooding areas and palustrine hydrochemistry results show substantial variabilities ranging from 65 c ph 6 41 1029 ppm alkalinity and 37 ppm calcium concentrations at the vents site to 21 c ph 8 13 and 800 ppm alkalinity and 14 ppm calcium concentrations at 1 km downstream were carbonate precipitation is no longer visible the set of linked subenvironments tend to merge into a larger scale geobody that defines the travertine system with a proximal area dominated by physicochemical processes and a distal extent with pervasive microbial and common macrophyte features the travertine system should not be understood as a fixed model and its limits as well as the existing subenvironments their extents and degree of overlapping will depend mainly on three factors 1 hydrothermal input 2 climate and 3 landscape perched past travertine deposits together with internal architectures and extent of the presently active travertine system allows thinking about constructive and destructive stages respectively thought as dominantly expanding and erosional periods alternation of these two evolutionary stages and their balance will dictate the volume of primary facies and potential reworking products a better understanding of these stages and their litho stratigraphic products will allow developing predictive stratigraphic and correlation models based on a sequence stratigraphic approach

holocene alluviation and hydrology in the upper thames basin a sequence of changing conditions for flooding and alluviation in the upper thames valley during the holocene has been identified and provisionally dated by the investigation of archaeological sites interstratified with alluvium archaeological survey suggests that the changes can be related to clearance and agricultural activity in the catchment area

centennial scale climate change in ireland during the holocene we examine mid to late holocene centennial scale climate variability in ireland using proxy data from peatlands lakes and a speleothem a high degree of between record variability is apparent in the proxy data and significant chronological uncertainties are present however tephra layers provide a robust tool for correlation and improve the chronological precision of the records although we can find no statistically significant coherence in the dataset as a whole a selection of high quality peatland water table reconstructions co vary more than would be expected by chance alone a locally weighted regression model with bootstrapping can be used to construct a best estimate palaeoclimatic reconstruction from these datasets visual comparison and cross wavelet analysis of peatland water table compilations from ireland and northern britain show that there are some periods of coherence between these records some terrestrial palaeoclimatic changes in ireland appear to coincide with changes in the north atlantic thermohaline circulation and solar activity however these relationships are inconsistent and may be obscured by chronological uncertainties we conclude by suggesting an agenda for future holocene climate research in ireland

river response to rapid holocene environmental change evidence and explanation in british catchments macklin m g jones a f lewin j 2010 river response to rapid holocene environmental change evidence and explanation in british catchments quaternary science reviews 29 13 14 1555 1576 sponsorship welsh assembly government and the higher education funding council for wales for funding this study through its support of the centre for catchment and coastal research at aberystwyth university

noncrystallographic calcite dendrites from hot spring deposits at lake bogoria kenya abstract complex calcite crystals are an integral component of precipitates that form around the orifices of the loburu and mawe moto hot springs on the shores of lake bogoria kenya two types of large up to 4 cm long noncrystallographic dendrites are important components of these deposits feather dendrites are characterized by multiple levels of branching with individual branches developed through crystal splitting and spherulitic growth scandulitic from latin meaning shingle dendrites are formed of stacked calcite crystals and are generally more compact than feather dendrites these developed through the incremental stacking of rectangular shaped calcite crystals that initially grew as skeletal crystals feather and scandulitic dendrites precipitated from the same waters in the same springs the difference in morphology is therefore related to microenvironments in which they grew feather dendrites grew in any direction in pools of free standing water provided that they were in constant contact with the solute conversely scandulitic dendrites grew on rims of dams where water flowed over the surface in concert with the pulses of spring water thus each calcite crystal in these dendrites represents one episode of crystal growth the orientation of the component crystals in scandulitic dendrites is controlled by the topography of the dam or surface not crystallographic criteria the noncrystallographic dendrites formed from spring waters with initial temperatures of 90 99 c surficial water cooling loss of co2 and presence of other elements that can interfere with crystal growth contributed to the formation of these unusual crystals

diagenesis or dire genesis the origin of columnar spar in tufa stromatolites of central greece and the role of chironomid larvae two greek pleistocene tufa stromatolites were examined petrographically and with stable isotope geochemistry to determine whether calcite spar is of primary or diagenetic origin the younger ca 100 ka tufa from zemeno primarily is micritic with primary columnar calcite spar restricted to areas immediately above chironomid larval tubes this relationship suggests that chironomid larval feeding behaviour is responsible for the development of zemeno tufa columnar calcite probably involving biological substances smeared onto the tufa surface most micritic crystals are not suitably oriented to allow later post depositional growth resulting in columnar fabrics the older ca 1 ma predominantly sparry tufa from nemea contains some chironomid tubes and organic cyanobacterial filaments preserved in crystal fans but also contains many fabrics found in primary speleothem spar columnar spar here is unlikely to be the result of post depositional crystal growth a comparison of stable isotopic trends between the two tufa deposits suggests that both contain interpretable seasonal trends and implies little or minor post depositional alteration of either tufa consequently there is no basis for the common assumption that sparry tufa fabrics must be of diagenetic origin

early cretaceous dendritic shrub like fabric in karstified peritidal carbonates from southern italy abstract lower cretaceous valanginian dendritic microfabrics occur in karstic cavities within fine grained shallow marine platform carbonates at san lorenzello southern italy they form dense micritic masses and clusters generally oriented perpendicularly to cavity surfaces surrounded by layered sparry cement individual dendrites typically sub millimetric in size have highly irregular margins and form distinctive shrub like masses ranging from compact and squat to elongate and highly branched the centimetric and irregularly elongate cavities appear to have formed through subaerial exposure and are almost entirely filled by the micritic dendrites and associated sparry crusts in size shape and micritic composition the dendrites broadly resemble a variety of similar fabrics including hot spring travertine shrubs and calcified microfossils such as cambrian angusticellularia which has analogs in present day lacustrine calcified cyanobacteria however the san lorenzello dendrites differ in occupying small cavities this cryptic microkarstic dripstone setting together with the often regular spacing and appearance of these dendritic fabrics may be more consistent with an abiotic origin these comparisons underscore the challenge of interpreting microdendritic carbonates fabrics in general

the bam iran earthquake of december 26 2003 from an engineering and seismological point of view abstract this paper is devoted to studying the destructive bam earthquake from an engineering seismological point of view on december 26 2003 a large earthquake of magnitude 6 7 m s shook the bam district located in southeastern iran about 80 of buildings totally collapsed several dozen villages were destroyed and tens of them were severely damaged more than 45 000 people were killed and 30 000 were injured according to the macroseismic data focal depth of the event was estimated at 7 2 km the event was associated with a 9 km surface rupture of the bam fault the maximum residual strike slip displacement is 5 cm which is left lateral the highest recorded peak ground acceleration is at bam station 0 98 g vertical and 0 87 g horizontal located about 1 5 km from the surface rupture the macroseismic analyses show that the epicenter of the quake is 1 5 km east of bam all of the masonry buildings totally collapsed in the epicentral area many semi engineered structures were heavily damaged and some of them collapsed engineered structures constructed according to the seismic code of iran have shown very good structural behavior without significant damage finally the earthquake intensity at the epicenter is determined as ix on the msk scale which strongly decreases with distance from the surface ruptures

botryoidal high magnesium calcite marine cements from the upper cretaceous of the mediterranean region abstract in both recent and ancient limestones marine cements which have a botryoidal morphology are generally thought to have precipitated as aragonite however upper cretaceous botryoidal cements from widespread mediterranean localities described here are interpreted as former high magnesium calcite petrographic features indicating an originally high magnesium calcite mineralogy include rhombic terminations to precursor crystallites and microdolomite inclusions minor element concentrations in the botryoids are depleted in strontium relative to calcitized skeletal aragonite a former calcitic mineralogy for cretaceous botryoids is in accordance with proposals that ocean chemistry at this time inhibited inorganic aragonite precipitation

northern european summer temperature variations over the common era from integrated tree ring density records tree ring chronologies of maximum latewood density are most suitable to reconstruct annually resolved summer temperature variations of the late holocene the two longest such chronologies have been developed in northern europe stretching back to the 2nd century bc and the 5th century ad we show where similarities between the two chronologies exist and combine portions of both into a new summer temperature reconstruction for the common era to minimize the transfer of potential biases we assess the contribution of the candidate reconstructions measurements and exclude data i from exceptionally young and old trees and ii produced by different laboratory technologies our new composite reconstruction reveals warmer conditions during roman medieval and recent times separated by prolonged cooling during the migration period and little ice age twentieth century warmth as indicated in one of the existing density records is reduced in the new reconstruction also affecting the overall millennial scale cooling trend over the late holocene 0 30uc per 1000 years due to the reduced biological memory typical for tree ring density measurements the new reconstruction is most suitable for evaluating the rate and speed of abrupt summer cooling following large volcanic eruptions copyright 2014 john wiley sons ltd

origin and diagenesis of quaternary travertine shrub fabrics rapolano terme central italy millimetre to centimetre sized arborescent shrub like calcite precipitates are common constituents of hot water travertine shallow pool deposits of quaternary age at rapolano terme tuscany italy in the presently forming travertines the shrubs consist of apparently random associations of i micrite aggregates and ii subhedral to euhedral rhombic spar crystal aggregates in thin section the micrite aggregates appear dark and the spar rhomb aggregates light giving the shrubs a mottled appearance travertines are basically produced by caco3 precipitation due to degassing and evaporation of the spring waters although biological influence may also stimulate precipitation the formation of masses of erect shrubs rather than dense crystal crusts that form on slopes is probably due to limited water flow in the pool environments microbes including bacteria and diatoms are important influences on shrub microfabric and external shape the micrite aggregates are associated with bacteriform bodies seen as tiny rods and spheres the micrite precipitates around these bodies and in adjacent biofilm spar rhomb precipitation appears to be external to the biofilm and may be related to the presence of diatoms which are locally closely associated with the spar rhombs although an essentially inorganic origin particularly for the more euhedral rhombs cannot be ruled out in the older quaternary travertines the original microfabric of the shrubs has been diagenetically altered the original mottled appearance of the shrubs has become uniformly dark and micritic and the evidence for the dual micritic and spar rhomb origin of the shrubs is obscured or destroyed spar micritization of the shrubs is probably due to abiotic and locally biotic dissolution previous studies did not recognize the diagenetic micritization and attributed shrub formation entirely to bacterial activity

acoustic properties in travertines and their relation to porosity and pore types abstract sonic velocities of pleistocene travertines were measured under variable confining pressures combined with petrographical characteristics and petrophysical data i e porosity permeability and density it was determined that travertine porosity pore types and cementation control compressional wave vp and shear wave velocity vs at 40 mpa confining pressures vp ranges between 3695 and 6097 m s and vs between 2037 and 3140 m s velocity variations in travertines are as with all carbonates primarily linked to sample heterogeneity i e differences in fabric texture and porosity they thus not necessarily emanate from changes in mineralogy or composition body wave velocities have a positive correlation with sample density and an inverse correlation with porosity the travertines sampled in extensional settings with normal faulting activity define a specific compressional wave velocity y axis versus porosity x axis equation i e log y 0 0048x 3 7844 that differs from the vp porosity paths defined by marine carbonates acoustic wave velocities are higher for travertines than for marine carbonates travertine precipitates form rigid rock frames often called framestone with large primary pores marine carbonates on the other hand often consist of cemented transported sediments resulting in a rock frame that permits slower wave propagation when compared to the continental limestones acoustic velocity variations are linked to variations in pore types mouldic pores macropores show faster wave propagation than expected from their total porosities microporosity interlaminar and interpeloidal porosity result in slower acoustic velocities framework pores and micro moulds are associated with lowered acoustic velocities while vug porosity is found above on and below the general velocity porosity trend not only the pore type but also pore shapes exert control on body wave velocities cuboid and rod like pore shapes increase the velocity while plate and blade like pore shapes have a negative effect on the velocity the study demonstrates how seismic sections in travertine systems can contain seismic reflections that are not caused by non carbonate intercalations but relate to geobody boundaries in which the seismic expression is function of porosity pore types and shapes this study provides and relates petrophysical data i e porosity permeability and acoustic velocities of travertines and is of importance for the interpretation of seismic reflection data in subsurface continental carbonate reservoirs

sedimentology three dimensional geobody reconstruction and carbon dioxide origin of pleistocene travertine deposits in the ballik area south west turkey the denizli basin in the west anatolian extensional province in western turkey is well known for its numerous travertine occurrences a combined sedimentological diagenetic and geochemical investigation is executed on the ece and faber travertines of the ballk area the largest travertine site in the denizli basin the first aim of this study is the reconstruction of a three dimensional geo model in combination with a detailed sedimentological description from fabric to lithotype lithofacies and geobody scale with a focus on integrating pore typing the second aim involves the delineation of the co2 origin of ancient travertine precipitating waters peloidal phyto and dendritic lithotypes dominate the studied travertines and honeycomb and bacteriform shapes and encrusted bacterial or fungal filaments related to their fabrics suggest a microbial influence the environment of travertine precipitation evolved from dominantly sub aqueous as represented by the sub horizontal and biostromal reed travertine facies to dominantly sub aerial in a thin water film resulting in the cascade waterfall and biohermal reed travertine facies a general progradation of the travertine mound is indicated by the occurrence of stacked waterfall travertines this results in sigmoidal clinoforms inside a general mound boundary configuration strontium and oxygen carbon isotope signatures of the travertines point to a mixing mechanism of palaeofluids with deeply originated heavy carbon co2 with lighter carbon co2 of shallow origin these deposits can thus be considered as endogenic travertines carbonates of the lycian nappes acted as main parent carbon source rocks the relative contribution of the lighter carbon isotopes is most likely to have originated from organic matter or soil co2 this study provides a unique three dimensional insight into the ballk travertine architecture that potentially can be used as an analogue for subsurface travertine reservoirs worldwide and illustrates the importance of the combined use of c 13 and sr 87 sr 86 signatures in the delineation of the co2 origin of travertine precipitating waters

the azuaje travertine an example of aragonite deposition in a recent volcanic setting n gran canaria island spain the azuaje travertines in the north of gran canary island crop out in the azuaje gorge which is incised into miocene volcanic breccias of the roque nublo formation this travertine is interesting because of the scarcity of travertines in the canary islands and its close relationship with recent volcanic events part of the travertine overlies a lava flow dated at 2420 40 years bp the travertine is composed mainly of aragonite in both perched systems on the gorge walls and in gorge bottom deposits parallel to the present stream perched systems include deposits from the feeder conduits within the roque nublo formation that spilled out through waterfalls and over barriers the gorge valley bottom system includes barrier and pool deposits the main laminated facies are composed mostly of large fibrous aragonite crystals while there are also common micritic and porous microfabrics shrubs coated grains coated bubbles and rafts are present in many of the deposits detailed study of the microfacies shows the presence of sparsely distributed biogenic features the 13c values are between 4 0 and 11 0 and the 18o values range between 11 0 and 2 0 vpdb these 13c values lie within the range of those of thermogene travertines fed by thermal waters that cooled downstream as indicated by the increase of the carbon and oxygen isotope values in that direction the common occurrence of fibrous radial fabrics is interpreted to be due to disequilibrium conditions during aragonite precipitation disequilibrium was likely caused by rapid co2 degassing of the thermalwaters that led to a rapid increase in the degree of aragonite saturation thus themorphology of the aragonite crystals and the isotopic composition indicate that the formation of the azuaje travertine was mostly due to abiogenic processes induced by rapid degassing of thermalwaters linked to the presence of a recent lava flow within the gorge in short the azuaje travertine shows the important role of volcanic activity in travertine deposition in the facies distribution as well as in the geochemical signatures of the deposits and so can be used as a recent analogue for ancient travertine deposits in volcanic settings

continental carbonates as a hydrocarbon reservoir an analog case study from the travertine of saturnia italy the pleistocene saturnia travertine central italy represents a possible analog of the pre salt continental carbonate reservoirs discovered in the santos and other basins in the south atlantic margin of brazil two subhorizontal travertine tabular bodies several tens of meters thick and extending over an area of have been studied in two quarries facies variations and associated petrophysical properties were reconstructed applying a multidisciplinary approach the saturnia travertine formed from a warm water spring is composed of various stacked carbonate banks separated by subaerial erosive phases and paleosols the lacustrine tabular bodies terraces and sills are made of crystalline crust shrub pisoid paper thin raft coated bubble reed and lithoclast breccia facies the from 4 to 8 supports an interpreted volcanic mantle source whereas the from 9 to 5 is in agreement with warm meteoric waters the ratio isotopic signature indicates a carbonate from dissolution of deep seated carbonates the facies reservoir properties were studied via porosity and permeability analysis of plugs three dimensional x ray computer tomography as well as image analysis on microscale under thin section and macroscale on large rock slabs to define various porosity indices a strong heterogeneity of the petrophysical properties and variable connectivity were observed porosity from 4 to 30 and permeability up to hundreds of md but no compartmentalization of the carbonate bodies is present

lateral and vertical variations in sedimentology and geochemistry of sub horizontal laminated travertines cakmak quarry denizli basin turkey abstract the laterally extensive sub horizontal laminated travertine deposits outcropping in the cakmak quarry denizli basin turkey allows reconstructing their three dimensional geobody architecture based on field observations detailed petrographic and geochemical analyses stable carbon and oxygen isotopes major and trace elements the most important controlling porosity permeability parameters in this lacustrine dominated facies in relation to microfacies and diagenetic modifications were constrained sedimentological analyses and the observed architectural geometries allowed to subdivide the sub horizontal carbonate succession into three main depositional units these units in turn based on macro and microscopic observations were subdivided into nine dominant lithotypes reflecting an overall shrub flat and a marsh pool depositional setting the shrub flat facies mainly comprises dendritic shrub crusts boundstone pustular grainstone and clotted micrite mudstone to boundstone in contrast the marsh pool environment is dominated by coated reed rudstone to boundstone cryptalgal silty bioclast rich bioturbated mudstone and peloidal packstones the diagenetic study revealed that the sediments were affected by dissolution cementation sparmicritization recrystallization and local formation of fe oxi hydroxides and chalcedony among the diagenetic products in particular the calcite cements were investigated applying micro analysis of stable carbon and oxygen isotopes accordingly the co variation between the obtained isotopic values and the elemental concentrations sr mg na and s point to a thermogene fluid system that likely circulated through the subsurface limestones dolomites and evaporites of the lycian nappes these findings ensure an in depth understanding of continental carbonate deposition i e sub aqueous travertines in the context of a lacustrine depositional system

fracture networks and strike slip deformation along reactivated normal faults in quaternary travertine deposits denizli basin western turkey abstract the denizli basin in the west anatolian extensional province in western turkey is known for its numerous quaternary travertine occurrences travertine morphology is often dependant on the relative position of the deposition with respect to basin bounding faults the travertine occurrences examined in this study are situated at the intersection of the locally e w oriented denizli basin and the adjacent ne sw oriented baklan graben in the ne based on an extensive field campaign including lidar scanning several high resolution fault fracture maps of five large quarries 300 m in length and 60 m in height are constructed in which this world class travertine deposit is currently excavated a structural analysis is performed in order to determine the tectonic overprinting of the travertine body and to derive the stress states of the basin after travertine deposition the mostly open non stratabound joints are several tens of metres long and often bifurcate creating a dense fracture network minor infill of the joints resulted in the presence of a few colour banded calcite veins based on the e w ne sw and nw se orientation of three dominant joint sets it is concluded that the joint network is caused by local n s extension alternated by nw se and ne sw extension exemplifying the presence of stress permutations in the quaternary high angle e w to wnw ese faults cross cut the quarries faults are filled with travertine debris and clastic infill of above lying sedimentary units indicative of the open nature of the faults the specific e w fault orientation in the locally e w trending denizli basin indicates that they initiated as normal faults a paleostress inversion analysis performed on kinematic indicators such as striations on the clayey fault infill and the sinistral displacement of paleosols shows that some of the normal faults were reactivated causing left lateral deformation in a transient strike slip stress field with a ne sw oriented 1

pleistocene holocene tectonic reconstruction of the ballik travertine denizli graben sw turkey de formation of large travertine geobodies at intersecting grabens abstract travertine geobodies have been identified as potential reservoir analogues to carbonate build ups in pre salt hydrocarbon systems to investigate travertine geobody deformation faults were mapped in 35 travertine quarries that excavate the ballik travertine i e a c 12 5 km2 large travertine geobody that precipitated at the intersection of the ne margin of the denizli basin and neighbouring baklan graben sw turkey this travertine precipitated from cooling carbonate saturated thermal spring waters that resurfaced along the margin fracture fault network and through neogene unconsolidated underlying sediments from the denizli basin floor to the uplifted graben shoulders fault orientation is dominantly wnw ese oriented with major basin faults showing a left stepping trend along the upper denizli margin travertine is only deformed by extensional normal faults along the lower margin travertine starts with a subhorizontal facies but evolves to a travertine facies formed by a sloping topography with a domal architecture paleostress inversion of fault slip data reveals that an early pleistocene nne ssw extensional transtensional phase initiated the wnw ese oriented graben facing normal fault network in the middle pleistocene the ballik fault network was left lateral strike slip reactivated because it acted as a transfer zone between the nw se extending neighbouring baklan basin and nw se extension along ne sw oriented margin faults of the dghs in this stress configuration travertine precipitated along the sw margin fault of the baklan graben after strike slip reactivation a late pleistocene to current nne ssw extensional stress regime reinstalled during which margin faults widened and active travertine precipitation moved to more central parts of the dghs as different tectonic regimes affect graben intersections reservoir analogues can have a complex deformation history driven by fault reactivation and recurrent stress permutations this study concludes that large travertine geobodies can form at graben intersections because of their susceptibility to enhanced fluid flow through the complex fault fracture network

the fluvial record of climate change fluvial landforms and sediments can be used to reconstruct past hydrological conditions over different time scales once allowance has been made for tectonic base level and human complications field stratigraphic evidence is explored here at three time scales the later pleistocene the holocene and the historical and instrumental period new data from a range of field studies demonstrate that croll milankovitch forcing dansgaard oeschger and heinrich events enhanced monsoon circulation millennial to centennial scale climate variability within the holocene probably associated with solar forcing and deep ocean circulation and flood event variability in recent centuries can all be discerned in the fluvial record although very significant advances have been made in river system and climate change research in recent years the potential of fluvial palaeohydrology has yet to be fully realized to the detriment of climatology public health resource management and river engineering

growth of fissure ridge travertines from geothermal springs of denizli basin western turkey fissure ridge travertines grown from geothermal springs of denizli basin southwestern turkey are investigated through stratigraphic structural geochemical and geochronological methods with the aim of understanding the growth of these elongate mound shaped structures two main types of travertine deposits are recognized 1 bedded travertines which grew as flowstone on sloping surfaces and form the bulk of fissure ridges and 2 banded travertines which grew as veins within the bedded travertine chiefly along its central feeding conduit stratigraphic and structural observations shed light on the bedded banded travertine relationships where the banded features grew through successive accretion phases crosscutting the bedded travertine or forming sill like structures the bedded and banded travertines alternated their growth as demonstrated by complicated crosscutting relationships and by the upward suture in places of banded travertine by bedded travertine that was in turn crosscut by younger banded travertine the bedded travertine is often tilted away from the central axis of the fissure ridge thus leaving more room for the central banded travertine to form u series ages confirm the bedded banded travertine temporal relationships and show that the growth of the studied fissure ridges lasted up to several tens of thousands of years during quaternary time the banded travertine was deposited mainly during cold events possibly in coincidence with seismic events that might have triggered the outflow of deep geothermal fluids c and o stable isotope and rare earth element data indicate a shallow feeding circuit for the studied structures with a fluid component deriving from a deeper geothermal circuit a crack and seal mechanism of fissure ridge growth is proposed modulated by the interplay of local and regional influencing factors and mechanisms such as geothermal fluid discharge paleoclimate tectonics and the progressive tilting of bedded travertine limbs over a soft substratum creating the necessary space for the central veins to grow

cyclic development of large complex calcite dendrite crystals in the clinton travertine interior british columbia canada abstract bands of large up to 4 cm long three dimensional crystallographic dendrites form the terrace fronts in an old travertine mound exposed near clinton british columbia the dendrites with their long axes perpendicular to the terrace front are characterized by numerous levels of branching each branch is formed of multitudes of skeletal rhombs four and six sided bipyramidal crystals or prismatic hexagonal crystals that are precisely aligned along crystallographic precepts although individual branches are formed of one type of subcrystal neighbouring branches may be formed of different subcrystal types highly supersaturated waters that were generated by rapid co 2 degassing of the spring water during its turbulent flow over the steep terrace fronts probably drove dendrite precipitation the presence of growth lines indicates that growth was episodic type i growth lines probably formed annually in response to seasonal climate changes whereas type ii growth lines which formed less frequently may reflect changes in the flow velocity and or flow patterns of the spring waters early diagenetic modification of the dendrites involved crystal face enlargement cements formed of trigonal prisms or needle fiber crystals microbial infestation that mediated substrate dissolution and or deposition of detrital calcite crystals that formed in the water column much of the diagenetic modification may have taken place during the periods when the dendrites had temporarily stopped growing the dendrites in the clinton travertine are an excellent example of complex episodic calcite crystal growth that was extensively modified by early diagenetic processes in a surface environment the same spring waters from which the dendrites were precipitated mediated much of the early diagenesis

genesis and diagenesis of travertine futamata hot spring japan abstract genetic and diagenetic processes of travertine were examined at futamata hot spring where both active and inactive subfossil and fossil travertines are present geochemical and geomicrobiological analyses of active travertines reveal that abiotic process of caco3 precipitation is predominant photosynthetic inhibition of caco3 precipitation occurs at the upstream while the cyanobacterial population is low in the downstream resulting in photosynthesis induced caco3 precipitation only in the midstream nonetheless microorganisms have an effect upon depositional fabrics and filamentous cyanobacteria possessing non acidic sheaths contribute to the particle trapping binding and the generation of pore space both active and inactive travertines are mainly composed of calcite however active travertine in the up midstream also contains some aragonite due to high rates of co2 degassing active and subfossil travertines are characterized by domal topography and relatively high flow rates are assumed due to the dominance of slope facies on the other hand fossil travertines are characterized by fissure ridge topography and relatively low flow rates are assumed due to the dominance of crest and marsh facies the elemental composition of travertines primarily reflects their constituent minerals and the active travertines consisting of both aragonite and calcite show higher sr ba na and k contents whereas travertines consisting solely of calcite show higher mg and mn contents due to elevated mn content bright cathode luminescence is exhibited by the primary calcite of active travertines most fossil travertines have experienced prominent diagenetic alteration in the vadose zone and are commonly cemented and recrystallized in addition to meteoric water percolating hot spring water was also involved in the diagenetic process combined with the results of u th dating our results suggest that the formation of fissure ridge travertines at futamata hot spring began approximately 20 thousand years ago ka via fault activity which terminated at around 7 ka and the domal travertines were formed by hot spring water discharging from several vents

colluvial and alluvial response to land use change in midland england an integrated geoarchaeological approach this paper presents geomorphic soils and palaeoecological data from a small sub catchment in the english midlands in an attempt to provide an integrated picture of holocene landscape change the area used has also been the focus of a multi disciplinary and long term archaeological survey raunds area project and so has a wealth of archaeological and historical data which can be related to the environmental record the paper combines these data much of which are only published in the archaeological literature with new interpretations based upon unpublished data and new data particularly from the hillslopes and new radiocarbon dating from the valley floor it is inferred that despite a long history of pastoral and arable agriculture since the neolithic bronze age colluviation on lower slopes significant soil redistribution and overbank alluviation only began to a measurable extent in the late saxon medieval period 9th century ad onwards it is suggested that this is due to a combination of land use factors principally the laying out of an intensive open field system and the establishment of villages combined with a period of extremes in climate well known throughout europe indeed the critical element appears to have been the social changes in this period that created this regionally distinctive landscape which happened to have a high spatial connectivity and facilitated intensive arable production with high tillage rates intense rainfall events during this period could therefore detach and mobilize high volumes of soil and the open field system facilitated transport to slope bases and valley floors the need for detailed and spatially precise land use data in order to interpret accelerated landscape change is stressed

hierarchical approach to define travertine depositional systems 3d conceptual morphological model and possible applications abstract 3d modelling represents a powerful tool to characterize the geobody architecture of depositional systems several examples have been proposed in literature both for marine carbonates and siliciclastics rocks for modelling quantitative data related to orientation shape and dimension are fundamental continental carbonates however are not considered yet likely because they cover a large range of deposits such as speleothems tufas lacustrine carbonates and travertines the interpretation of the depositional environments of the latter is still in fact debated by the scientific community however the interest in continental carbonates and especially travertines increased over the last decades due to the discovery of supergiant unconventional reservoirs in the southern atlantic i e the so called pre salt play aim of this paper is to present an innovative workflow to investigate and describe continental carbonates as geobodies based on a hierarchical approach applied to three large scale travertine settings i e terme di san giovanni italy pamukkale turkey and the lapis tiburtinus travertines italy travertine depo systems are divided in three different depo zones namely proximal intermediate and distal that are characterized by different depo elements depo shapes and depo facies finally a 3d morphological model is created based on numerical and vector approaches and interpolation of both the model can be applied to seismic data of brazilian and angolan pre salt highlighting the similarities between these systems and for the first time the scale independence of these depositional system representing an important advantage in their interpretation the 3d model and the approach proposed facilitates seismic interpretation allowing to define and characterize geometries of inaccessible geological contexts

introduction aapg hedberg research conference on microbial carbonate reservoir characterization conference summary and selected papers with the recent discovery of hydrocarbons in microbial carbonate reservoir facies along the south atlantic margins industry is keen to further the understanding of the origin and development of nonmarine lacustrine to marine microbial carbonates the nature of the depositional and diagenetic characteristics of microbialite and associated facies and the sedimentary and petrophysical properties of microbial carbonate petroleum reservoirs in this regard the authors of aapg getting started series 19 microbial carbonate reservoirs mancini et al 2010 found that a vast literature on microbes and their functions in geological processes and products ranging from biogeochemistry to geomicrobiology sedimentary petrology and stratigraphy was available however only a small part of this literature deals with microbial carbonates as petroleum reservoirs further these authors reported that sparse available literature exists on microbial carbonate reservoirs formed in lacustrine and continental settings and on carbonate reservoirs of abiotic origin in general to help address these shortcomings an aapg hedberg research conference was proposed to focus on microbial carbonate reservoir characterization with an emphasis on depositional settings of microbial and abiotic carbonate reservoirs especially in lacustrine settings associated with rift basins the proposal was accepted august 21 2010 and the hedberg conference was held in houston texas last june 3 8 2012 with 85 attendees from 10 countries the conference was dedicated to wayne m ahr who passed away in november 2011 he was one of the conference organizers one of the intended field trip leaders and a friend to many at the conference the following overview of microbial carbonates is modified from sections 1 and 2 of aapg getting started series 19 microbial carbonate reservoirs mancini et al 2010 microbes are defined as microorganisms visible only under a microscope some examples are bacteria fungi molds algae and protozoa unlike the older classification of living organisms

dating the homo erectus bearing travertine from kocabas denizli turkey at at least 1 1 ma abstract since its discovery within a travertine quarry the fragmentary cranium of the only known turkish homo erectus the kocabas hominid has led to conflicting biochronological estimations first estimated to be 500 ka old the partial skull presents a combination of archaic and evolved features that puts it as an intermediate specimen between the dmanisi fossils homo georgicus and the chinese zhoukoudian skulls homo erectus respectively dated to 1 8 to 0 8 ma here we present a multidisciplinary study combining sedimentological paleontological and paleoanthropological observations together with cosmogenic nuclide concentration and paleomagnetic measurements to provide an absolute chronological framework for the upper fossiliferous travertine unit where the kocabas hominid and fauna were discovered the 26 al 10 be burial ages determined on pebbles from conglomeratic levels framing the upper fossiliferous travertine unit which exhibits an inverse polarity constrains its deposition to before the cobb mountain sub chron that is between 1 22 and 1 5 ma the alternative match of the normal polarity recorded above the travertine with the jaramillo subchron lower limit 1 07 ma may also be marginally compatible with cosmogenic nuclides interpretation thus the proposed minimum age of 1 1 ma for the end of massive travertine deposition the actual age of the fossils is likely to be in the 1 1 1 3 ma range this absolute date is in close agreement with the paleoanthropological conclusions based on morphometric comparisons implying that kocabas hominid belongs to the homo erectus s l group that includes chinese and african fossils and is different from middle and upper pleistocene specimens furthermore this date is confirmed by the large mammal assemblage typical of the late villafranchian because it attests to the antiquity of human occupation of the anatolian peninsula and one of the waves of settlements out of africa this work challenges the current knowledge of the homo erectus dispersal over eurasia

3 d imaging of the upper crust beneath the denizli geothermal region by local earthquake tomography western turkey abstract the denizli basin and its surroundings are one of the regions that have high seismic activity and rich geothermal fields in western anatolia in the first half of year 2000 an increasing seismic activity was observed around the denizli basin without a large mainshock occurrence a temporary seismic network consisting of 28 stations were deployed to observe the seismic activity in the region by the scientific and technological research council of turkey marmara research center earth and marine science institute tubitak mam emsi in this study one and three dimensional vp and vp vs structure of the denizli basin have been determined by using the travel times of the 635 recorded earthquake data firstly one dimensional inversion schema was performed to stabilize initial velocity model and to have more reliable hypocentral locations then an iterative and simultaneous three dimensional inversion procedure was carried out to obtain 3 d high resolution seismic velocity models furthermore to assess the solution quality of our inversion we conducted a series of resolution tests we concluded high resolution 3 d vp and vp vs seismic velocity models for the upper 20 km of the crust beneath the denizli basin and surroundings and interpreted the results in the context of known geologic and tectonic units the resulting 3 d vp models define the geometry of the basin sediment thickness and intrusive magmatic bodies as well as regions of anomalous velocity the vp vs models help to constrain the location and geometry of the faults zones of weakness and gas or fluid saturated formations with high pore pressure zones all tomographic results show that there is a strong correlation between local seismicity and the high vp and vp vs anomalies consequently this relationship indicates that the reason of the high seismicity in the denizli basin depends on activity of hydrothermal system as well as tectonic regime

geobody architecture of continental carbonates gazda travertine quarry suttő gerecse hills hungary abstract the gazda quarry is one of the largest outcrops of the present day sutt travertine complex that is situated close to the town of sutt hungary in the pannonian basin sedimentological and petrographical analyses show that the gazda travertine body is built out of phytohermal wavy laminated massive and flat laminated travertine lithofacies representing reed mound slope lacustrine and palustrine depositional environments respectively based on petrographic analyses the following three main textural features were recognized that allow to describe the most common microscopic features 1 micrite textures 2 micritic coatings and crusts and 3 different types of clasts each major lithofacies is characterized by a particular association of these textural types the geometry of the travertine beds follows the antecedent land surface a ne sw striking pre pleistocene valley it is proposed that in this valley travertine precipitation took place along a gently sloping terrain the gazda travertine system was fed by at least two groundwater springs one of them was located ne of the quarry from which waters were flowing along the axis of the valley the other source was located to the east of the gazda quarry and waters joined the main water course along the valley closest to the confluence a phytohermal mound developed with lateral slope and eventual pond depositional systems onlapping and interfingering with the flat laminated lithofacies indicate alternating activity of the two springs fractures observed in the quarry are mainly related to postdepositional gravitational sliding however neotectonic forces resulting in nw se tension also played a role in the formation of the fractures stable oxygen and carbon isotope analyses show that water temperature was approximately 25 c petrographic studies indicate that only syn diagenetic processes affected the precipitates therefore the original stable oxygen isotope signatures characteristic of the depositional environment were preserved detailed sedimentological and geochemical study of the gazda travertine complex allowed small scale facies characterization providing information about the ancient depositional environment and the heterogeneous nature of these carbonates

shrub and pore type classification petrography of travertine shrubs from the ballik belevi area denizli sw turkey petrographical and petrophysical properties of the turkish ballik belevi travertine shrubs demonstrate the necessity of reservoir oriented classifications for shrub related lithotypes and associated pore types the presented shrub related lithotype classification incorporates morphology size and fabric which are linked to specific pore types and sizes the travertines show highly complex pore networks as observed from computed tomography reconstructions making them of interest for the development and optimization of pore characterization methodologies and techniques following an upscaling approach porosity 3 15 and permeability 0 505 md strongly vary for the ballik belevi travertines the highest porosities and permeabilities are measured for horizontal samples dominated by slightly dissolution enlarged intershrub and interdigit growth framework porosity mostly found for dendritic shrubs the presented shrub and pore type classification can be applied to shrubs worldwide studying outcrop analogues of continental carbonates helps to better understand heterogeneities lateral variability and properties of pre salt cretaceous continental carbonate reservoirs offshore brazil and angola

trigonal dendritic calcite crystals forming from hot spring waters at waikite north island new zealand amorphous silica and calcite form the deposits in the vent and on the discharge apron of waikite spring 100 ws 100 which is located in the waikite geothermal area on north island new zealand these precipitates formed from spring water that has a temperature of 90 c and a ph of 8 1 8 8 the opaline silica is restricted to areas around the vent where cooling and evaporation of the spring water triggered precipitation the calcite deposits in the spring vent and on the discharge apron are formed of large up to 15 cm long asymmetrical dendrite crystals that are characterized by multiple levels of branching branches grew preferentially from the downflow side of their parent branch all branches have a trigonal transverse cross section except in areas where competition for growth space induced merger of neighboring crystals the primary branches of the dendrite crystals are sub perpendicular to the substrate even in areas where the discharge apron slopes at a high angle up to 80 on the steeper parts of the discharge apron the plate like primary branches form the floors of the small terrace pools whereas their distal edges form the rims of the pools growth of these dendrite crystals is attributed to abiotic processes high levels of saturation with respect to calcite were caused by rapid co2 degassing of the sheets of spring water that flowed down the steep discharge apron calcite crystals with different crystal morphologies characterize other springs near this spring the variation in crystal morphologies from spring to spring is attributed to different levels of saturation that are related to the initial pco2 of the spring water upon discharge and the rate of co2 degassing at each spring

mid to late holocene climate change an overview the last 6000 years are of particular interest to the understanding of the earth system because the boundary conditions of the climate system did not change dramatically in comparison to larger glacial interglacial changes and because abundant detailed regional palaeoclimatic proxy records cover this period we use selected proxy based reconstructions of different climate variables together with state of the art time series of natural forcings orbital variations solar activity variations large tropical volcanic eruptions land cover and greenhouse gases underpinned by results from general circulation models gcms and earth system models of intermediate complexity emics to establish a comprehensive explanatory framework for climate changes from the mid holocene mh to pre industrial time the redistribution of solar energy due to orbital forcing on a millennial timescale was the cause of a progressive southward shift of the northern hemisphere nh summer position of the intertropical convergence zone itcz this was accompanied by a pronounced weakening of the monsoon systems in africa and asia and increasing dryness and desertification on both continents the associated summertime cooling of the nh combined with changing temperature gradients in the world oceans likely led to an increasing amplitude of the el nin o southern oscillation enso and possibly increasingly negative north atlantic oscillation nao indices up to the beginning of the last millennium on decadal to multi century timescales a worldwide coincidence between solar irradiance minima tropical volcanic eruptions and decadal to multi century scale cooling events was not found however reconstructions show that widespread decadal to multi century scale cooling events accompanied by advances of mountain glaciers occurred in the nh e g in scandinavia and the european alps this occurred namely during the little ice age lia between ad w1350 and 1850 when the lower summer insolation in the nh due to orbital forcing coincided with solar activity minima and several strong tropical volcanic eruptions the role of orbital forcing in the nh cooling the southward itcz shift and the desertifi cation of the sahara are supported by numerous model simulations other simulations have suggested that the fingerprint of solar activity variations should be strongest in the tropics but there is also evidence that changes in the ocean heat transport took place during the lia at high northern latitudes with possible additional implications for climates of the southern hemisphere sh

traditional and multivariate techniques in the interpretation of floodplain sediment grain size variations the vertical and horizontal variation of sedimentary fades is the raw data for the interpretation of flood plain history from which palaeohydrological inferences are frequently drawn mixed and fine floodplain sediments present problems of interpretation because of a large grain size range and frequent polymodality caused by the mixing of process associated grain size components this paper discusses the use of traditional grain size statistics and the use of the mode and multivariate statistics the mode although much neglected is indicative of up profile grain size changes and has practical advantages over the mean for mixed and fine floodplain sediments constrained cluster analysis and principal components analysis are used directly on coulter counter results these techniques can rapidly divide a floodplain profile into grain size units and indicate the principal vectors of grain size variation which will be related to the changing processes of deposition principal components analysis reveals the importance of the medium to fine silt category in accounting for grain size variations suggesting that a critical factor in determining the type of alluvial unit deposited is the degree to which it has received fine suspended material grain size data from the lower severn are used to construct a cm diagram which is compared with a texture triangle from both the cm and multivariate analysis a generalized backswamp profile is constructed which shows the existence of a coarser top unit caused by the addition of a fine to medium sand component to the underlying sediment during the late holocene

travertines depositional morphology and the bacterially constructed constituents abstract investigation of travertine accumulations throughout central italy and the west central u s has shown that the carbonate is precipitated in response to both inorganic and organic processes individual deposits range up to 85 m thick and hundreds of square kilometers in areal extent all of the carbonate is low magnesian calcite water chemistry temperature and morphology of the accumulation greatly influence the constituents comprising these deposits harsh environmental situations favor inorganic deposits while increasingly more moderate conditions result in the formation of a greater abundance of organically precipitated material morphological variations of travertine deposits recognized include 1 waterfall or cascade 2 lake fill 3 sloping mound fan or cone 4 terraced ound and 5 fissure ridge gross morphology internal stratification and constituents comprising these deposits vary systematically depending upon the type of accumulation and chemistry of the waters bacterially precipitated calcite forms a large percentage of the carbonate in many travertine accumulations exceeding 90 of the framework grains comprising some of the lake fill deposits bacteria are among the first taxa to inhabit and reproduce in harsh spring environments and produce a variety of fascinating constituents the bacteria are primarily rods generally 0 2 m in diameter and less than 1 0 m in length the rods readily decay resulting in calcite crystals loaded with micropores the basic building block of bacterially constructed travertine is a clump of bacteria averaging 20 m in diameter enclosed in a single crystal of calcite aggregates of these crystals produce a variety of deposits including 1 crudely laminated carbonate mud 2 finely laminat d layers of mud 3 intraclasts 4 foam rock and 5 shrubs the shrubs are most striking commonly forming layers 1 3 cm thick but also producing bacterial pisoids at some locales bacterial stromatolites composed of layers of shrubs alternating with finely laminated layers of bacterial mud comprise essentially the entire deposit the shrub layers are the result of flourishing summer growth of bacteria and furthermore show remarkable daily laminae 0 1 0 5 mm thick the importance of bacteria in the formation of travertine and their universally recognized abundance in modern sediments provides an impetus for a reexamination of the role of bacteria in the origin of other types of ancient deposits

the planform mobility of river channel confluences insights from analysis of remotely sensed imagery river channel confluences are widely acknowledged as important geomorphological nodes that control the downstream routing of water and sediment and which are locations for the preservation of thick fluvial deposits overlying a basal scour despite their importance there has been little study of the stratigraphic characteristics of river junctions or the role of confluence morphodynamics in influencing stratigraphic character and preservation potential as a result although it is known that confluences can migrate through time models of confluence geomorphology and sedimentology are usually presented from the perspective that the confluence remains at a fixed location this is problematic for a number of reasons not least of which is the continuing debate over whether it is possible to discriminate between scour that has been generated by autocyclic processes such as confluence scour and that driven by allocyclic controls such as sea level change this paper investigates the spatial mobility of river confluences by using the 40 year record of landsat imagery to elucidate the styles rates of change and areal extent over which large river confluence scours may migrate on the basis of these observations a new classification of the types of confluence scour is proposed and applied to the amazon and ganges brahmaputra meghna gbm basins this analysis demonstrates that the drivers of confluence mobility are broadly the same as those that drive channel change more generally thus in the gbm basin a high sediment supply large variability in monsoonal driven discharge and easily erodible bank materials result in a catchment where over 80 of large confluences are mobile over this 40 year window conversely this figure is 40 for the amazon basin these results highlight that i the potential areal extent of confluence scours is much greater than previously assumed with the location of some confluences on the jamuna brahmaputra river migrating over a distance of 20 times the tributary channel width ii extensive migration in the confluence location is more common than currently assumed and iii confluence mobility is often tied to the lithological and hydrological characteristics of the drainage basins that determine sediment yield

bacterial shrubs crystal shrubs and ray crystal shrubs bacterial vs abiotic precipitation hot water travertine deposits commonly contain shrub like morphologies on the centimeter to meter scale that range from highly irregular forms bacterial shrubs to features that display regular geometric patterns crystal shrubs and ray crystal crusts the bacterial shrubs have been previously recognized as the product of bacterially induced precipitation whereas the ray crystal crusts have been described as due to dominantly abiotic precipitation the bacterial shrubs have a highly irregular morphology similar to woody plants in contrast end member crystal shrubs display distinct crystal habits and regular repeating morphologies i e they commonly have attributes of noncrystallographic as well as crystallographic dendrites there is a complete gradational relationship between the bacterial shrubs and crystal shrubs ray crystal crusts are large fan shaped features composed of subparallel extremely coarse bladed crystals of calcite all three types bacterial shrubs crystal shrubs and ray crystal crusts contain either a dense tangle of bacterial body fossils and or micron sized pores the micropores are bacterial molds the immediately enveloping spar crystals around all three morphologic types are devoid of bacterial body fossils and micropores the bacterial shrubs crystal shrubs and ray crystal crusts are to differing degrees the product of bacterially induced precipitation as well as abiotic mineral precipitation the differences in morphology are due to the relative contribution of bacterially induced precipitation as compared with that of abiotic mineral precipitation bacterially induced precipitates can form in environments too chemically harsh or otherwise inhospitable for other taxa to thrive epiphyton and renalcis commonly formed in occult environments under conditions inhospitable to other taxa consideration of the published descriptions and interpretations concerning epiphyton and renalcis and by analogy the origin of bacterial shrubs have led to the conclusion that epiphyton and renalcis also are bacterially induced precipitates

geobody architecture genesis and petrophysical characteristics of the budakalasz travertines buda hills hungary subsurface pre salt lower cretaceous reservoir systems encountered offshore brazil and angola that consist of porous continental carbonates are difficult to access because of the limited core material that is under concession therefore it is important to study comparable continental carbonate analogues such as travertines and lacustrine carbonates that potentially possess similar porosity and permeability characteristics the budakalasz pleistocene travertines buda hills hungary have been studied from a sedimentological geochemical and reservoir properties point of view in order to understand their formation petrophysical properties and 3d reservoir architecture the three dimensional geobody architecture of the budakalasz travertines illustrates the potential complexity of kilometre scale continental carbonate systems heterogeneous low angle sloping travertine lobes consisting of terrace slope smooth slope and reed facies are covered by a lime mudstone dominated gastropod and charophyte rich marsh pool facies the observed facies represent a change from a subaerial travertine to a palustrine to lacustrine system reflecting the ceasing of the system due to tectonic uplift the dominant paleo flow direction of the sloping lobes was towards the danube depression with several subordinate flow systems identified the srco isotope geochemical signatures reflect travertine precipitation at ambient to superambient temperatures from meteoric derived fluids with a mixed co2 origin of the marine carbonate substrate rocks a potential atmospheric and a soil derived component although the uniform signatures of the stable oxygen and carbon isotopes in addition to petrographic observations suggest partial diagenetic isotopic resetting the primary isotope trends seem to have been preserved a reservoir oriented facies evaluation in the three dimensional geobody frame of the budakalasz carbonates based on porosity and permeability core plug analyses reveals their heterogeneous nature terrace smooth slope and marsh pool facies have considerable porosities of 5 15 while the porosity of the reed facies may reach up to 27 permeability of all facies is strongly anisotropic mainly controlled by a better connectivity along layer parallel primary pores the reconstruction of the 3d geobody architecture of the budakalasz lobe complex coupled to its geochemical and petrophysical properties provides a unique dataset that contributes in understanding fossil travertine systems

evaluating the geogenic co2 flux from geothermal areas by analysing quaternary travertine masses new data from western central italy and review of previous co2 flux data abstract quantification of carbon fluxes between solid earth and its atmosphere is necessary to understand the global geological carbon cycle some of the main co2 contributors are metamorphism and magmatic mantle degassing co2 is discharged from active and quiescent volcanoes fault zones geothermal systems and co2 rich groundwater here a new method for the estimation of the geogenic flux of co2 from tectonically active regions based on the volume composition and age of travertine deposits is proposed the method is applied to the travertine deposits of western central italy where travertine deposition is driven by degassing of co2 charged groundwater results show that the study areas are characterized since middle pleistocene by diffuse co2 degassing processes with time averaged co2 fluxes ranging between 1 24 0 12 106 mol y 1 km 2 and 1 38 0 42 106 mol y 1 km 2 these values are of the same order of magnitude of carbon dioxide fluxes measured by different methods in western central italy and are higher than the global baseline co2 flux from high heat flow regions the review of the available 234u 230th and 14c data shows that the co2 degassing processes that affects western central italy nowadays were already active at least 350 ka ago proving that this region is a globally relevant case for the study of earth degassing considering the widespread occurrence of travertine deposits in tectonically active areas worldwide the proposed approach can be used as a reliable tool to estimate the co2 flux in different geodynamic settings within system earth

presalt stratigraphy and depositional systems in the kwanza basin offshore angola the lower cretaceous presalt section in the kwanza basin contains an excellent petroleum system that includes synrift strata barremian overlain by a sag interval aptian and capped by the loeme salt the upper synrift is generally limestone with widespread mollusk packstones and grainstones coquinas deposited in a fresh to moderately saline alkaline lake the sag interval is characterized by carbonate platforms and silica rich isolated buildups formed in highly evaporated highly alkaline lakes shrubby dendritic microbially influenced boundstones and intraclast spherulite grainstones accumulated in shallow water on platform tops microbial cherts were deposited as organic buildups on large isolated structural highs basinward west of platforms and they apparently formed at low temperatures in very alkaline lake water shrubby boundstones and microbial cherts have vuggy pores that are primary and result in high permeability wackestones and packstones with calcitic grains mainly spherulites in dolomite or argillaceous dolomite were deposited in slightly deeper low energy sag environments in addition clays especially stevensite precipitated out of the silica rich highly alkaline lake waters during sag deposition calcite precipitated on the shallow lake floor with morphologies that ranged from spherulites to shrubs and included a continuum of intermediate forms spherulites probably precipitated just below the sediment water interface spherulites and shrubby calcites are commonly recrystallized spherulites floating in stevensite probably formed in deeper lacustrine environments organic rich mudstones were deposited in even deeper lacustrine environments in synrift and sag intervals and they are likely the source of most hydrocarbons in this system these interpretations are supported by seismic core petrographic and stable isotope data

a sub centennial scale optically stimulated luminescence chronostratigraphy and late holocene flood history from a temperate river confluence river confluences can be meta stable and contain valuable geological records of catchment response to decadal millennial scale environmental change however in alluvial reaches flood stratigraphies are particularly hard to date using 14c in this paper we use a novel combination of optically stimulated luminescence osl and multi proxy sedimentological analyses to provide a flood record for the severn teme confluence over the last two millennia which we compare with independent european climate records the results show that by c 2000 bp the severn teme confluence had stabilized and overbank alluviation had commenced initially this occurred from moderately high flood magnitudes between c 2000 1800 bp 50 bce ce 150 but was followed from 1800 1600 bp ce 150 350 by fine alluvial deposition and decreased flood intensity from 1600 1400 bp ce 350 550 the accumulation rate increased with evidence of large flood events associated with the climatic deterioration of the dark age cold period following a period of reduced flood activity after c 1400 bp c ce 550 larger flood events and increase in accumulation rate once again became more prevalent from c 850 bp c ce 1100 coincident with the start of the medieval climate anomaly a period associated with warmer wetter conditions and increased land use intensity this state persisted until c 450 bp c ce 1500 after which increased flood magnitudes can be associated with climatic variations during the little ice age we demonstrate that from the combination of high resolution dating techniques and multiple analytical parameters distinctive phases of relative flood magnitude vs flood duration can be determined to a detailed chronological precision beyond that possible from 14c dating this permits the identification of the regional factors behind floodplain sedimentation which we correlate with the intensification of land use and climatic drivers over the last two millennia

sedimentology and petrophysical analysis of pre salt lacustrine carbonate reservoir from the santos basin southeast brazil lacustrine carbonate deposits mark the rift sag sedimentation stage of the so called pre salt section of the campos and santos basins in the southeast brazilian continental shelf these salt sealed carbonate reservoirs form deep water giant and prolific oil fields that are currently responsible for approximately 70 of the brazilian oil and gas production in the santos basin the sag stage carbonates are represented by the aptian barra velha formation characterized by exotic textural and compositional features whose origin development and correlation with petrophysical properties have been broadly discussed in the last decade a geological and petrophysical study has been performed based on core samples plugs and thin sections of a well in the barra velha formation from the eastern santos basin the analyzed core interval was grouped into six depositional facies constituted by the association of five key textural components 1 crystal shrubs 2 calcite spherulites 3 hybrid forms 4 mud grade carbonates and dolomite and 5 intraclasts the relationship between the depositional framework and the poroperm system as evidenced by petrographic image analysis and ct scan data is highly complex the depositional control over porosity is erratic mainly due to the extensive diagenetic and possible hydrothermal overprint dolomite cementation dolomitization pervasive silicification and dissolution processes are the main primary porosity modifiers petrophysical analysis indicates that intraclastic and spherulitic grainstones rudstones affected by matrix dissolution may present the best reservoir properties in certain intervals even surpassing the shrubby framestones which are widely regarded as the best reservoir facies this study seeks to contribute to an emerging body of research about the brazilian pre salt lacustrine carbonates broadening the geological knowledge about these deposit while providing new data to improve hydrocarbon forecast and recovery

multiscale approach to micro porosity quantification in continental spring carbonate facies case study from the cakmak quarry denizli turkey carbonate spring deposits gained renewed interest as potential contributors to subsurface reservoirs and as continental archives of environmental changes in contrast to their fabrics petrophysical characteristics and especially the importance of microporosity 1 mu m are less understood this study presents the combination of advanced petrophysical and imaging techniques to investigate the pore network characteristics of three common and widespread spring carbonate facies as exposed in the pleistocene cakmak quarry denizli turkey the extended pond the dipping crystalline proximal slope facies and the draping apron and channel facies deposits formed by encrustation of biological substrate integrating mercury injection capillary pressure bulk and diffusion nuclear magnetic resonance nmr nmr profiling and brunauer emmett teller bet measurements with microscopy and micro computer tomography mu ct shows that nmr t 2 distributions systematically display a single group of micro sized pore bodies making up between 6 and 33 of the pore space average nmr t 2 cut off value 62 ms micropore bodies are systematically located within cloudy crystal cores of granular and dendritic crystal textures in all facies the investigated properties therefore do not reveal differences in micropore size or shape with respect to more or less biology associated facies the pore network of the travertine facies is distinctive in terms of i the percentage of microporosity ii the connectivity of micropores with meso to macropores and ii the degree of heterogeneity at micro and macroscale results show that an approach involving different nmr experiments provided the most complete view on the 3 d pore network especially when microporosity and connectivity are of interest

abiotic versus biotic controls on the development of the fairmont hot springs carbonate deposit british columbia canada the relict fairmont hot springs deposit formed largely of carbonates covers an area of 0ae 5k m 2 and is up to 16 m thick the triangle shaped discharge apron which broadens down valley is divided into a proximal part with beds dipping at 10 and a distal part with beds dipping at 10 to 15 the deposit is formed of the 1 basal macrophyte 2 lower carbonate 3 middle clastic 4 upper carbonate and 5 upper clastic sequences two charcoal samples embedded in the lower carbonate sequence yielded dates of 8690 90 and 8270 70 cal yr bp indicating that much of the deposit formed post glacially during the early to mid holocene deposit aggradation ceased in the mid to late holocene when the fairmont creek valley was incised the lower and upper carbonate sequences which are the thickest sequences are composed of nearly equal parts of travertine abiotic and tufa biotic with feather dendrite travertine radiating dendrite travertine and stromatolite tufa dominating competition between calcite precipitation rates and biotic growth rates controlled the distribution of tufa and travertine across the discharge apron calcite and biotic growth rates were controlled largely by flow velocity across the apron which in turn was controlled by topography and regular fluctuations in spring water discharge volume during times of high spring discharge slow sheet flow over the proximal part of the apron promoted stromatolite growth whereas fast turbulent flow on the distal part of the apron induced rapid feather dendrite formation during times of low spring discharge quiescent shallow evaporative pools conducive to radiating dendrite formation formed on the proximal part of the apron whereas slow flow on the distal part promoted stromatolite growth facies with high calcite supersaturation experienced rapid abiotic dendrite growth that precluded most biotic growth

seismicity and focal mechanisms associated with the subduction of the juan de fuca plate beneath the olympic peninsula washington abstract two and a half years of data from an expanded telemetered seismic network on the olympic peninsula reinforce the conclusion that the juan de fuca plate is subducting beneath washington however the rate of seismicity is presently much lower than typical rates at other convergent margins the located earthquakes can be divided into two groups on the basis of depth at the coast a shallow zone extends to a depth of approximately 20 km while a deep zone begins at 25 km on the eastern edge of the peninsula the shallow zone has thickened to 30 km and the depth to the top of the deep zone has increased to 45 km the rate of crustal seismicity is much lower on the peninsula than in the adjacent puget sound region the deep zone is 5 to 10 km thick and dips to the east at an angle of about 11 the deep events appear to be occurring in the upper part of the subducting oceanic lithosphere focal mechanisms were constructed for 16 events in the suite of deep events with magnitudes ranging from 1 6 to 4 3 the solutions show primarily normal faulting with the p axes normal to the slab and the t axes displaying a range of angles within the slab with the average t axis in the downdip direction small events with down dip tension in the downgoing slab are consistent with the slab sinking under its own weight several strike slip events may be caused by a shearing within the slab these features are consistent with ongoing subduction of the juan de fuca plate beneath north america

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research