changes in the geochemical parameters of karst lakes over the past three decades the case of plitvice lakes croatia abstract one of the major reasons for the increase in global air temperature since the early 20th century is considered to be the increase in the atmospheric co 2 concentration karst relief is considered an important carbon sink but it can also be a natural source of carbon and co 2 emission aquatic systems in karst areas facilitate carbon exchange between the karst and the atmosphere often through groundwater geochemical carbonate rock dissolution carbon sink and in the form of secondary calcium carbonate precipitation possible carbon source the protected area of plitvice lakes national park located in the karst region of croatia was chosen as a case study on karst geochemical processes the lakes are also specific for their authigenic calcite precipitation in the form of tufa barriers and lake sediment physical and chemical data temperature ph ca 2 hco 3 mg 2 and co 2 concentrations calcite saturation index si calc calcite dissolution ionic ratio ir calc and mg ca ratio from water samples collected at 8 locations 2 springs 2 rivers and 4 lakes from 1981 to 2014 were studied the data were not collected systematically so long term changes have been mostly assessed through comparison between parameters from two selected periods 1981 1986 and 2010 2014 and through temporal correlations for each observed parameter in each calendar month for the 33 years studied an increase in air and water temperature ca 2 and hco 3 concentrations calcite saturation index si calc calcite dissolution ionic ratio ir calc and a decrease in the mg ca ratio were observed no statistically significant change was observed for ph or co 2 and mg 2 concentrations average discharge rates did not display any significant change over the past three decades however there was a change in their seasonal distribution the significant increase in ca 2 and hco 3 concentrations at lake locations were primarily caused by an increase in ca 2 and hco 3 values in the water of the springs simultaneously mg 2 concentrations remained constant which indicates higher levels of limestone calcite dissolution than dolomite dissolution one of the reasons for this could be higher air soil temperatures resulting in higher soil co 2 production which appears to result in the higher dissolution of calcite exclusively an increase in hco 3 concentrations at the springs implies that karst groundwater is a carbon sink furthermore the fact that the spatial decrease in hco 3 concentration in downstream waters was the same during the 1981 1986 and 2010 2014 periods implies that the entire observed karst lake system itself is a carbon sink temporal and spatial changes in si calc and ir calc values in surface waters were mainly attributed to an increase in the intensity of bioactivity which is in turn connected with an increase in water temperature

climatic implications of the quaternary fluvial tufa record in the ne iberian peninsula over the last 500 ka the drainage area of the iberian ranges ne spain houses one of the most extensive quaternary fluvial tufaceous records in europe in this study tufa deposits in the anamaza mesa piedra and ebron river valleys were mapped stratigraphically described and chronologically referenced from u th disequilibrium series amino acid racemization and radiocarbon methods tufa deposits accumulated in cascades barrage cascades and related damming areas developed in stepped fluvial systems the maximum frequency of tufa deposition was identified at 120 ka marine oxygen isotope stage mis 5e 102 ka mis 5c 85 ka mis 5a and 7 ka mis 1 probably under warmer and wetter conditions than today additional phases of tufa deposition appear at 353 ka end of mis 11 258 180 ka mis 7 and 171 154 ka mis 6 although most tufa deposition episodes are clearly correlated with interstadial periods the occurrence of tufa deposits during the penultimate glaciation mis 6 is remarkable indicating that the onset of this stage was climatically favourable in the iberian peninsula biostatic conditions and the dynamics of karstic systems regulating tufa deposition seem to be sensitive to the precipitation regime controlled by shifts in the position of north atlantic atmospheric belts and summer insolation regulated by orbital forcing

sedimentology of quaternary perched springline and paludal tufas criteria for recognition with examples from guadalajara province spain outcrop scale geometries and bed relationships of ambient temperature freshwater carbonates are poorly understood because many described tufas have been dismantled by erosion and present only part of a particular depositional model at the field scale four end member models encompass the tufa continuum 1 perched springline 2 paludal 3 fluvial and 4 lacustrine tufas individual bed types can occur with variable dominance within several of these models but one or more beds are characteristically dominant only within a single tufa model so it can be differentiated from relatively isolated outcrop fragments two models perched springline tufas and paludal tufas are known in outline only in the literature despite being present within the quaternary deposits of most karstic regions perched springline tufas generally form lobate fan shaped mound morphologies on hillslopes and develop from single or multiple spring resurgences mature deposits show a subhorizontal top and a steep face on the downflow side the steep outer zones of tufa mounds may be developed into cascades with moss curtains or can be dominated by shallow rimstone pools according to face angle tufa deposits lying downslope of the mounds are usually detrital in nature especially if some dismantling of the mound has occurred the relatively thin subhorizontal lobe top deposits commonly contain organic rich deposits paludal tufas develop predominantly in waterlogged valley bottom situations where line sourced waters emerge from valley side and bottom aquifers lime mud precipitation predominates in these sites mud is deposited as subhorizontal laminites that thin towards the valley axis and downstream of resurgences tufa spring mounds may form where lesser volumes of water are involved individual tussocks phytoherm cushions of grasses and rushes are the most diagnostic feature of the model but sapropels and peats may be intercalated diagenesis in both models is rapid lithification of individual beds is virtually instantaneous and always occurs before the decay of the associated living vegetation the resulting highly porous and permeable fabrics remain fresh in holocene tufas but aggrading neomorphism and partial spar infill of vegetation moulds is common in older deposits dissolution in many perched springline tufas is small scale many large cavities are primary but with later coatings of speleothems early removal of organics from paludal tufas is responsible for autobrecciation and differential compaction

new stratigraphic and geochemical data on the holocene environment and climate from a tufa deposit at direndall mamer valley luxembourg tufa deposits are proven to record high quality palaeoenvironmental and palaeoclimatic information they also appear to be influenced by human activities as indicated by the late holocene tufa decline observed in europe from the atlantic optimum when tufa should be well developed regarding climatic conditions the studied tufa comes from the mamer valley in luxembourg direndall as it covers a broad part of the holocene this deposit offered a great opportunity to discuss modalities and timing of the tufa decline and the human impact on fluvial formations since the early holocene recent fieldwork at direndall allowed the collection of new stratigraphic data and samples for a geochemical study we investigate calcite stable isotopes as records of past temperature and humidity conditions comparisons with the environmental reconstructions from a previous malacological study show strong consistency with the 13c record and suggest humidity might have been the main factor controlling environment evolutio

a characterisation of the coastal tufa deposits of south west western australia abstract located in the south west coastal zone of western australia are numerous tufa deposits which are registered as threatened ecological communities tec the tufas occur in near shore shallow bedrock settings and are associated with local groundwater discharge depositional facies mineralogy elemental chemistry and water quality were investigated for five key deposits two conceptual environmental models are identified the first the cascade to barrage pool model is associated with coastal waterfall zones the second a perched spring line and barrage pool model is located predominantly in the supratidal zone tufa morphology texture mineral composition and elemental chemistry vary within and between sites both phytoclast and lithoclast allochthonous and phytoherm forms of tufa are identified depending on location within the facies calcite and to a lesser extent aragonite and mg calcite dominate tufa mineralogy with diagenetic modifications apparent tufa water chemistry is generally na cl hco3 dominated however na cl concentrations increase at sites situated within the supratidal zone currently the most likely potential threat posed to these deposits is increasing nutrient levels in spring waters from agricultural land use within the catchments this could in the future impact on tufa development

influences on the carbonate hydrochemistry of mound spring environments lake eyre south region south australia abstract mound spring structures composed of tufa precipitated from near ambient temperature spring waters are rare consequently the hydrochemical evolution of the water and the processes that control carbonate deposition in these systems are not well understood this study analysed the water from 3 mound springs in an arid environment in the vicinity of lake eyre south south australia samples were tested for major ion chemistry and stable isotope ratios of water 2 h 1 h and 18 o 16 o most co 2 degasses from water i before emergence as it ascends in the fracture derived spring conduit system below the spring opening and ii after emergence in the turbulent upper tail environment between the spring vent pool and the tail delta however modern carbonate precipitation was generally restricted to tail delta environments spatially disconnected from the areas of strongest co 2 degassing in addition to co 2 degassing and carbonate precipitation evapotranspiration and heterotrophy were inferred to be processes controlling the chemical evolution of water flowing through the tail delta based on considerations of the geometry of the tail delta and evapotranspiration rates it was inferred that infiltration is an important process in determining the tail delta size and hence the morphology of the mound spring environment a reactive transport model was used to assess the importance of these processes for the evolution of carbonate hydrochemistry the model outcomes showed that water loss via evapotranspiration does not significantly affect tufa precipitation despite the springs being located within an arid environment heterotrophy was considered in the model in order to reproduce observed ph and carbonate concentrations highlighting the role of vegetation in controlling the water chemistry the modelling approach adopted here provides a generic framework for the analysis of calcareous spring deposits and places quantitative constraints on data based process conceptualisation

freshwater carbonates within a late triassic siliciclastic fluvial system in a gondwana rift basin the maleri formation india abstract spring related carbonates are valuable repositories for information on physical and biotic environments of the past however for mesozoic and earlier records their use is limited due to their low preservation potential and difficulties in accurate identification of the carbonate type this study aims to characterise the source of carbonate clasts preserved as thin beds of cross bedded grainstones in late triassic siliciclastic fluvial deposits the maleri formation pranhita godavari rift basin india the microfabric and stable isotopic compositions of the grainstones and thin and discontinuous beds of impure limestones of this formation are presented here these features help in identifying the freshwater carbonate precipitating environments that existed in an ancient continental rift basin though such deposits are not primarily preserved in this case the microfabric of the carbonate grains provides evidence for carbonate precipitation in aquatic environment related to karstic springs taking together the microfabric stable isotopic compositions as well as the associated geological and palaeontological information it could be shown that the calcium carbonate precipitation took place in palustrine pools related to tufa like spring systems and in alluvial swamps under a pluvial climatic setting this research thus demonstrates that carbonate grains derived from spring related carbonate deposits formed mainly near the margins of rift basins can be incorporated into nearby siliciclastics if interpreted correctly they can be used in reconstructing ancient karstic carbonate environments even when in situ primary record is not preserved therefore making it possible to access the information stored in freshwater carbonates

structures associated with the northern end of the 1999 chi chi earthquake rupture central taiwan implications for seismic hazard assessment abstract the surface rupture of the 1999 chi chi earthquake m w 7 6 trendsmore than 100 km in a north south direction surface deformation at the northernend stops abruptly at an area between the tachia river and the taan river where abroad pop up structure with east to northeast strike can be found that has a trenddifferent from the north south striking main thrust we combine the absolute ele vation data before and after the chi chi earthquake to obtain the regional verticaldisplacement and the magnitude of the pop up structure the greatest uplift couldreach as high as 15 16 m using deformation magnitude and the area balancingmethod we measure the depth of the detachment to show the subsurface geometryof the chelungpu fault at its northern end this shows that the geometry of thechelungpu fault controls termination of the surface rupture and the depth of thedetachment controls the amount of deformation introduction perhaps the most unexpected geological feature asso ciated with the chi chi earthquake

slip rates on the chelungpu and chushiang thrust faults inferred from a deformed strath terrace along the dungpuna river west central taiwan the chelungpu fault produced the september 1999 m w 7 6 chi chi earthquake central taiwan the shortening rate accommodated by this structure integrated over several seismic cycles and its contribution to crustal shortening across the taiwanese range have remained unresolved to address the issues we focus our study on the chelungpu and chushiang thrust faults within the southernmost portion of the chi chi rupture area structural measurements and available seismic profiles are used to infer the subsurface geometry of structures the chushiang and chelungpu faults appear as two splay faults branching onto a common ramp that further north connects only to the chelungpu surface trace we survey a deformed strath terrace along the dungpuna river buried under a 11 540 309 years old fill deposit given this age the dip angles of the faults and the vertical throw determined from the offset of the strath terrace across the surface fault traces we estimate slip rates of 12 9 4 8 and 2 9 1 6 mm yr on the chelungpu and chushiang faults respectively these yield a total shortening rate of 15 8 5 1 mm yr to be absorbed on their common decollement at depth this total value is an upper bound for the slip rate on the chelungpu fault further north where the chushiang fault disappears and transfers shortening to adjacent faults combining these results with the recently constrained shortening rate on the changhua blind thrust reveals that all these frontal faults presently absorb most of the long term horizontal shortening across the taiwanese range they thus stand as the major sources of seismic hazards in this heavily populated area the return period of earthquakes similar to the chi chi event over a 80 km long stretch of the western foothills is estimated to be 64 years this value is an underestimate because it assumes that all the faults locked during the interseismic period slip only during such large events comparison with historical seismicity suggests that episodic aseismic deformation might also play a major role in accommodating shortening

differences in the 14c age δ13c and δ18o of holocene tufa and speleothem in the dinaric karst we studied holocene speleothems and tufa samples collected in numerous caves and rivers in the dinaric karst of croatia slovenia bosnia and herzegovina as well as serbia and montenegro differences in the formation process of tufa and speleothems are discussed in the context of their isotopic composition 14 c 13 c and 18 o as well as the chemistry of surface water rivers lakes and drip water in caves the physical and chemical parameters monitored in the surface water tufa precipitation and drip water speleothem precipitation show that more stable conditions accompany speleothem rather than tufa formation this is particularly obvious in the water temperature variations 2 22 c in surface water and 7 12 c in drip water and in saturation index variation 3 11 in surface water and 1 6 in drip water the range of 14 c ages recorded by holocene speleothems v12 000 yr is wider by several thousands years than that of holocene tufa samples v6000 yr n 13 c values for tufa samples range from 312x to 36x and for speleothem samples from 312x to 3x reflecting higher soil carbon and or vegetation impact on the process of tufa than on speleothem formation the differences in n 18 o values of tufa and speleothem samples from different areas reflect different temperature conditions and differing isotopic composition in the water the study shows that speleothems from the dinaric karst can be used as global palaeoclimatic records whereas tufa records changes in the local palaeoenvironment 2003 elsevier science b v all rights reserved

sedimentology and stable isotopes from a lacustrine to palustrine limestone deposited in an arid setting climatic and tectonic factors miocene pliocene opache formation atacama desert chile abstract field relations petrography gis and geochemistry of a late miocene pliocene limestone the opache formation calama basin atacama desert chile shows that depositional facies diagenetic histories and isotopes differ from eastern to western parts of the basin we recognize two facies lacustrine characterized by ostracod diatom mudstone and wackestone and palustrine characterized by both shallow water and pedogenic features gis analysis of the basin topography reveals an intrabasinal low in the eastern area and steeper hydrological gradients to the west with the calama constriction restricting flow between east and west petrography and geochemical results confirm that the calama constriction influenced depositional parameters ponding groundwater to the east forming a shallow lake and creating palustrine conditions to the west our analyses indicate that lake waters were less enriched in 13c or 18o than palustrine waters even though petrologic studies show that the lacustrine carbonates have a complex diagenetic history derived from groundwater rich in dissolved minerals this seemingly contrary observation can be reconciled if an important source of water for the western carbonates was sourced from the pacific ocean and was less evolved whereas eastern limestones precipitated from water which had become depleted in 18o during transport from the east today moisture from the pacific very rarely if ever reaches inland as far as calama indicating that during the late miocene mid pliocene breakdown in the temperature inversion due to weakened or absent upwelling in the cold coastal pacific current allowed moisture from the pacific to reach inland this changing atmospheric circulation pattern may have also affected upper level airflow that today blocks eastern sourced moisture from crossing the andes allowing it to reach farther westward into the atacama region during the late miocene pliocene together these moisture sources were sufficient to produce carbonate rich palustrine and lacustrine environments in the calama basin

crustal deformation in taiwan results from finite source inversions of six mw 5 8 chi chi aftershocks 1 we inverted strong motion data for the finite source parameters of six large aftershocks of the 1999 chi chi taiwan earthquake to investigate seismogenic structure in taiwan for each event we derived a preferred model by testing different focal mechanisms hypocenters rupture velocities and dislocation risetimes as well as different combinations of stations in more than 1000 inversions we documented how the fits between the waveforms and the corresponding synthetics deteriorated as the hypocenter and focal mechanism deviate from those of the preferred model if the deviation in focal mechanisms and hypocenters is less than 20 and 5 km respectively we generally recovered 80 of the preferred model s synthetic waveform fit unlike the dislocation risetime the rupture velocity used in the inversion had a strong influence on the waveform fits in this study we also used the slip models to study fault geometry two of the aftershocks ruptured on the southern extension of the main shock slip area one strike slip aftershock nucleated within the basement but ruptured mainly within the overlying sedimentary strata suggesting that seismogenic deformation in the basement can influence shallow structures p axes of the derived models have azimuths consistent with current plate motion finally gps displacement derived from the six slip models can explain 80 of the postseismic deformation observed in the aftershock regions indicating that studies of postseismic deformation must take into account the cumulative effects of large shallow aftershocks

variations of fluvial tufa sub environments in a tectonically active basin pleistocene teruel basin ne spain abstract the pleistocene tortajada fluvial deposit occurs in the eastern active margin of the teruel basin it developed in the early stages of opening of the basin and at present is disconnected to the alfambra river the preserved deposits show that the fluvial system consisted in three different sub environments including upper terraces ponds and cascades the main facies are framestones of stems phytoclastic rudstone framestone of bryophytes peloidal and filamentous stromatolites mudstone and detrital conglomerates and slope breccias facies these facies are arranged in three different sequence types all of them showing a lower detrital term followed by pond and in cases cascade deposits the microfacies analyses reveal that both biotic and abiotic processes performed an important role in the deposition within the river isotopic analyses 18 o from 8 58 to 6 70 vpdb and 13 c from 7 44 to 3 97 vpdb are indicative of meteoric water within a hydrologically open system the carbonate hinterland rocks together with a semi arid to sub humid climate favored carbonate accumulation within the river our results point out that the location morphology and sedimentary sequences of the tortajada fluvial system had an important tectonic control the situation of the main and secondary faults controlled the paleomorphology of the river floor thus cascades are found in areas of important step faults whereas the spaces between faults were occupied by fluviatile lacustrine areas in addition the development of the different sedimentary sequences was also a reflection of movements of these faults in short our study may confirm that tectonism is an important control on tufa development

rapid cold water formation and recrystallization of relict bryophyte tufa at the fall creek cold springs alberta canada the fall creek tufa is a relict mid to late holocene freshwater carbonate spring deposit that is formed almost entirely of calcite encased cratoneuron commutatum gametophytes the spring is presently active emitting 13 c meteorically derived waters but it is not precipitating calcite wood embedded in the youngest part of the tufa yielded a radiocarbon 14c date of 310 50 years bp the oldest parts of the deposit could not be dated by radiocarbon methods because of a lack of embedded organics the fall creek tufa however probably began forming 5000 years bp in response to the same wet climatic conditions that initiated calcite precipitation at miette hot springs in jasper national park and the cave and basin hot springs in banff national park the relict deposit is composed largely of calcite cements that were precipitated around the bryophytes with lesser amounts of internal sediments the tufa formed through a repeated four stage developmental process that involved i encrustation ii enc

the deepening of the atlantic water in the lofoten basin of the norwegian sea demonstrated by using an active reduced gravity model 1 the norwegian atlantic current nwac as a poleward eastern boundary current is to be considered as the northern limb of the meridional overturning circulation in the north atlantic moc it transports warm and saline atlantic water aw northward toward the arctic ocean before cooling and mixing with cold and low saline water masses return it to the north atlantic to contribute in the moc in this study we focus on the aw in the lofoten basin lb of the norwegian sea ns where it occupies a wider and deeper domain than farther south and north it comprises the major heat reservoir in the ns with contact with the atmosphere and as such is an important area for cooling and buoyancy loss we show that the deepening of the aw is mainly caused by the reduced northward flow in the lb manifested in the deep counter current encountered by the polar frontal jet we demonstrate this effect by using an active reduced gravity model with a topographically steered deeper flow to achieve maintenance of volume transport the model shows that observed differences must be balanced by an oppositely directed deeper flow in the lb the ocean appears to achieve maintenance of volume transport of aw due to buoyancy loss and varying deeper currents by adjusting the vertical extension of aw resulting in a substantial deepening in the lb based on the good fit between the model and observations the suggested mechanism appears to be credible and feasible

a sedimentary facies model for stepped fluvial tufa systems in the iberian range spain the quaternary piedra and mesa valleys stratigraphic and sedimentological analyses of the quaternary tufa and associated deposits in the piedra and mesa river valleys allowed a number of stages of their sedimentary evolution to be characterized and a depositional sedimentary model for this north central sector of the iberian range spain to be established the proposed sedimentary facies model may explain tufa arrangements in other medium to high gradient stepped fluvial tufa systems with narrow transverse profiles occurring in temperate semi arid areas in both recent and past scenarios there are several tufa deposits within the piedra and mesa river valleys that over a maximum thickness of about 90 m record one or more stages of tufa deposition produced following the fluvial incision of the bedrock or previous tufa deposits each depositional stage begins with coarse detrital sedimentation six fundamental vertical sequences of tufa facies with small amounts of detrital material reveal the sedimentary processes that occurred in different fluvial environments channel areas with i free flowing water ii barrages and or cascades and iii dammed water and palustrine floodplains the proposed sedimentary model involves narrow stepped fluvial valleys in which tufa cascades were common alternating intervals of bryophyte and stromatolite facies commonly formed at some cascades many of these represented barrage cascade structures that consisted of phytoclast rudstones thick phytoherms of mosses and associated stromatolites and curtain shaped phytoherms of stems upstream of these structures dammed areas with bioclastic sands and silts developed and palustrine vegetation grew the channel stretches between barrages and or cascades were loci for extensive stromatolite growth in fast flowing water the palustrine floodplain was home to pools and drainage channels the model also explains the growth of some barrages in the river piedra that surpassed the height of the divide with the diffluence of the main channel into a secondary course forming other tufa deposits in the area the distribution and abundance of certain types of tufa facies in fluvial basins may be an indicator of differences in their gradients the facies studied in this work suggest that the gradient of the ancient river piedra was steeper than that of the ancient river mesa assuming similar scenarios for climate and hydrology the depositional settings mentioned above and their dimensions would have been determined mainly by the gradient and width of the associated river valleys this sedimentary model may also be useful for inferring variations in other river basin slopes as well as accounting for the presence of tufas in areas that normally have no permanent water input

horizontal coseismic deformation of the 1999 chi chi earthquake measured from spot satellite images implications for the seismic cycle along the western foothills of central taiwan 1 the 1999 chi chi earthquake mw 7 6 broke a major thrust fault along the western foothills of the central range of taiwan we have measured the horizontal coseismic displacement field by correlating optical satellite images acquired before and after the earthquake these data reveal the fault trace and a clockwise rotation of surface displacements toward the north with much larger displacements and strain in the hanging wall at the surface coseismic slip increases from 5 6 m near the epicenter to 10 11 m to the north in the epicentral area we observe a left lateral strike slip zone trending n125 e and farther north a fault zone trending n s with a right lateral component the data were modeled using elastic dislocations the fault geometry consists of a shallow

paleohydrological implications of late quaternary fluvial deposits in and around archaeological sites in syria abstract the importance of fluvial processes to the development of late quaternary landforms in arid regions is well established particularly for the american southwest in contrast much less information exists about past fluvial processes for other arid regions such as arabic countries in the middle east this paper reviews the characteristics of late quaternary fluvial deposits and landforms in syria an arid country with little previous quaternary geomorphic research relatively detailed information has been obtained from areas adjacent to archaeological sites because of collaborative activities with geomorphologists and other geoscientists such activities have resulted in intensive field surveys and associated results of complementary archaeological studies of lithic artifacts are useful for establishing the chronology of fluvial deposits although the number of existing studies is limited the available information points to marked changes in the mode of fluvial processes in response to late quaternary climatic change fluvial sedimentation was enhanced during the wet periods of mis 3 4 the pleistocene holocene transition and the mid holocene in contrast the lgm was characterized by limited fluvial sedimentation under a drier climate as well as enhanced carbonate precipitation near the land surface to form calcrete and oncoids

facies architecture geochemistry and palaeoenvironmental reconstruction of a barrage tufa reservoir analog betic cordillera s spain continental carbonates are currently of high interest for the oil and gas industry as they have proved to be good reservoir rocks in brazil and angola offshore oil fields in this article a tufa system in which continental carbonates formed mainly in the pliocene rambla becerra tufa system guadix basin betic cordillera s spain is described in detail and a model proposed for its formation and evolution through time several stages of tufa growth have been identified in the field intercalated between stages of progradation of alluvial fan sediments the tufa system connects laterally with the fluvial system developed in the axial valley of the guadix basin during the pliocene and the pleistocene indicating that the tufa formation was coetaneous with the periods of lateral expansion of the fluvial system floodplain that in previous works have been interpreted as more humid stages and potentially warmer the absence of extraclasts in the tufa sediments points to the low activity of the alluvial fans during the tufa formation and therefore supports the idea that the main tufa growth happened during more humid stages and the alluvial fans developed further during the more arid periods which is consistent with other recent findings in the guadix basin the tufa growth is represented by four main stages the second one bearing the best example to study as a potential reservoir analog as the main outcrop is a discrete body with a specific geometry and facies distribution this main outcrop is a mound shaped tufa build up formed by prograding sigmoids of clastic tufa interpreted as the ramp like buttresses developed after a barrage in a barrage tufa system from a preliminary isotopic study of the carbonates forming the barrage tufa system and by comparison with other tufas and travertines the oxygen and carbon stable isotopes point to an intermediate situation between a palustrine tufa and a travertine this information when added to the sedimentological data supports the idea that water feeding the tufa system probably had different sources a meteoric one coinciding with the surface runoff and a groundwater one probably in the form of springs fed by groundwater from the nearby aquifers that still exist in the mesozoic carbonates that form the external zones of the betic cordillera in the area

does climate control the morphological fabric of freshwater carbonates a comparative study of holocene barrage tufas from spain and britain abstract calcium carbonate production in most freshwater tufa systems is controlled by a combination of physico chemical precipitation and biomediation associated with procaryote microphyte biofilms inorganic precipitation is dominant under turbulent flow regimes whereas biomediation necessitates sluggish flow or static water we show here that temperature is also likely to affect tufa formation rates and architecture leading to the development of a clearly definable range of fabrics two contrasting models are proposed warm semi arid tufas well seen in the ruidera pools national park albacete province central spain where tufa barrages consist of vertical narrow rimmed arcuate structures frequently these are bounded both upstream and downstream by deep lakes laterally accreting mammilate stromatolites dominate the upper two thirds of lake margin subaqueous overhangs whereas conical growth forms dominate shady basal parts of subaqueous overhangs dense reed stands grow in thin peats on top of the vertical lake margin walls resistivity survey and percussion augering show up to 20 m of earlier lake fill which is banded into dark and pale beds the upper 10 m accumulated in 4600 years there is little or no preservation of organic material within these deposits cool temperate tufas typified by slowly accumulating barrage tufas at caerwys n wales and alport n derbyshire uk transverse barriers across valleys are dominated by arcuate buttress developments built up of downstream facing tabular carbonate sheets pools upstream of the barriers are shallow dominated by clotted lime mud and organic sapropels in their depocentres and stromatolite dominated laminar to low domes or oncoidal facies in broad marginal zones marginal stands of semi aquatic vegetation are rooted in thick peats but frequently are also encrusted around their exposed stems by oncoidal carbonate fabric preservation is good for the carbonate material however marginal peats rapidly oxidise and stem encrustations collapse to produce cylindrical oncoid beds depocentre sapropels are always preserved and contain important pollen records otherwise rare in carbonate regions carbonates in both models accumulate relatively rapidly they have a moderate preservation potential within late cenozoic terrestrial successions the distinctly different characteristics of their preserved fabrics should allow recognition of two contrasting climatic models for fluvial barrage tufas in ancient deposits

facies evidence of hydroclimatic regime shifts in tufa depositional sequences from the arid naukluft mountains namibia the naukluft mountains on the eastern edge of the central namib desert contain numerous largely inactive fluvial tufas within headwater streams of the ephemeral tsondab river which currently terminates in a vlei in the namib sand sea extensive tufa barrage deposits have been mapped and described along the brandfontein river a small 6 5 km long tributary of the tsondab river here a series of large barrages have developed along the river system which culminate in a large tufa cascade feature at the mountain front tufa facies at brandfontein include cemented colluvial and fluvial gravels and boulders moss tufas as well as reed and root facies the sequences provide evidence of several cut and fill phases which are interpreted as indicating alternating periods of tufa deposition and fluvial downcutting the brandfontein tufas are used to propose a three phase arid fluvial tufa deposition model in which erosive high magnitude low frequency floods punctuate periods of quiescence and tufa deposition extensive downstream prograding ramped barrages and tufa cemented fluvial gravels are key components of this tufa deposition model which illustrates the role of climate and topography in shaping tufa deposit morphologies

gps measurement of postseismic deformation following the 1999 chi chi taiwan earthquake 1 in the 15 month period september 1999 to december 2000 after the 1999 chi chi taiwan earthquake mw 7 6 about 80 campaign surveyed gps stations in central taiwan were occupied up to seven times furthermore seven continuous gps stations were put into operation in the epicentral region mostly within three weeks after the main shock gps data from these near field stations and some pre existing far field stations were utilized to study the postseismic deformation following the chi chi earthquake the postseismic displacements of the gps stations were approximated by a combination of an exponential transient decay function with a relaxation time of 86 days and a postseismic linear rate change stations on the hanging wall displayed west northwesterly horizontal displacements of up to 252 mm and uplift as large as 229 mm postseismic displacements are much larger to the south near the epicenter of chi chi main shock than in the north where the maximum coseismic displacement occurred stations on the footwall show only small displacements the postseismic gps data were inverted to infer the deeper fault geometry and afterslip distribution based on a four segment fault model with its shallow part constrained by coseismic fault geometry deduced from gps and seismological studies the optimal model requires the lower fault segment to be a horizontal plane at a depth of 10 4 km consistent with a model based on gps data taken during the first three months after the main shock and other geological or geophysical studies the maximum afterslip 459 mm occurs in the hypocentral region and in the northern part of the decollement slip of about 430 mm also occurs in the southern part of the decollement the afterslip moment inferred from 15 months of gps data is 4 7 1019 n m approximately 2 3 times the seismic moment released by aftershocks this implies that a major part of the postseismic deformation is aseismic

the crystallographic fabric and texture of siderite in concretions implications for siderite nucleation and growth processes the crystallographic fabric of siderite in siderite concretions has been determined for upper carboniferous westphalian a non marine concretions and lower jurassic pliensbachian marine concretions compositional zoning indicates that individual siderite crystals grew over a period of changing pore water chemistry consistent with the concretions being initially a diffuse patch of cement which grew progressively the siderite crystallographic fabric was analysed using the anisotropy of magnetic susceptibility which is carried by paramagnetic siderite the siderite concretions from marine and non marine formations exhibit differences in fabric style although both display increases in the degree of preferred siderite c axis orientation towards the concretion margins the westphalian non marine siderites show a preferred orientation of siderite c axes in the bedding plane whereas the pliensbachian marine siderites have a preferred orientation of c axes perpendicular to the bedding in addition a single marine concretion shows evidence of earlier formed inclined girdle type fabrics which are intergrown with later formed vertical c axis siderite fabrics the marine and non marine fabrics are both apparently controlled by substrate processes at the site of nucleation which was probably clay mineral surfaces siderite nucleation processes on the substrate were most probably controlled by the bio chemistry of the pore waters which altered the morphology and crystallographic orientation of the forming carbonate the preferred crystallographic orientation of siderite results from the orientation of the nucleation substrate fabric changes across the concretions partially mimic the progressive compaction induced alignment of the clay substrates while the concretion grew during burial

sedimentary patterns in perched spring travertines near granada spain as indicators of the paleohydrological and paleoclimatological evolution of a karst massif perched spring travertines of the granada basin south spain constitute a perched system with four well defined steps which are formed by several facies associations deposited in different sub environments travertine pools dams and cascades these perched travertines are considered as a freshwater reef system with a facies zonation and stratigraphic architecture closely resembling that of marine reef terraces and prograding carbonate platforms the travertine deposits have been dated by 230 th 234 u and 14 c methods as in other mediterranean areas the travertine deposition occurred episodically during warm and wet interglacial periods coinciding with isotopic stages 9 7 and 5 and with the transition between isotopic stages 2 1 during these periods underground dissolution large outflow in the springs and subsequent calcium carbonate precipitation occurred in the same way that evolution of reef systems indicates sea level changes the geomorphology age and architecture of perched spring travertine systems may be used to interpret former climatically controlled changes in outflow in base level marked by the altitude of springs and in the chemistry of spring waters thus aggradation or climbing progradation may indicate an increase of outflow at the spring progradation with toplap is due to a stable base level and conversely dowlapping progradation may signify that the base level was gradually dropping therefore the travertines can be considered semiquantitative indicators of the paleohydrological evolution of karstic massifs and used as an important terrestrial proxy climate record d 2003 elsevier science b v all rights reserved

structural geology of a classic thrust belt earthquake the 1999 chi chi earthquake taiwan mw 7 6 abstract we document the structural context of the 1999 chi chi earthquake m w 7 6 in western taiwan which is one of the best instrumented thrust belt earthquakes the main surface break and large slip 3 10 m is on two segments of the shallow otherwise aseismic bedding parallel chelungpu sanyi thrust system which shows nearly classic ramp flat geometry with shallow detachments 1 6 km in the pliocene chinshui shale and mio pliocene kueichulin tungkeng formations however rupture is complex involving at least six faults including a previously unknown deeper thrust 8 10 km on which the rupture began we compare the coseismic displacements with a new 3d map of the chelungpu sanyi system the displacements are spatially and temporally heterogeneous and well correlated with discrete geometric segments of the 3d shape of the fault system geodetic displacement vectors are statistically parallel to the nearest adjacent fault segment and are parallel to large scale oblique fault corrugations the displacement magnitudes are heterogeneous at several scales which requires in the long term other non chi chi events or significant aseismic deformation the chelungpu thrust has a total displacement of 14 km but the area of largest chi chi slip 10 m is on a newly propagated north chelungpu chinshui detachment 0 3 km total slip which shows abnormally smooth rupture dynamics

holocene palaeoenvironments from the direndall tufa luxembourg reconstructed from the molluscan succession and stable isotope records this paper reports the results of new malacological analyses from a thick tufa sequence at direndall luxembourg the study is temporally contextualised with radiocarbon dates and an age depth mod

cyanobacterial tufa calcification in two freshwater streams ambient environment chemical thresholds and biological processes abstract calcareous freshwater streams near bad urach southwest germany were studied to determine the environmental limits to cyanobacterial calcification daily variations in temperature ph calcium concentration and alkalinity were measured at seasonal intervals from september 1993 to january 1995 in two small woodland streams with lengths of 1 0 and 1 5 km the principal cause of supersaturation in these fast flowing streams is inorganic carbon dioxide outgassing from resurging groundwater locally enhanced by turbulence at waterfalls and cascades photosynthetic uptake of carbon dioxide and temperature effects are negligible nonetheless organic substrates particularly cyanobacteria dominated microbial mats and biofilm significantly localize precipitation by providing suitable nucleation sites precipitation rates on artificial substrates up to 2 2 mm yr on limestone correlate with high saturation index values copper substrates inhibited microbial colonization and received negligible encrustation tufa formation and external calcium carbonate encrustation of cyanobacteria are conspicuous where the annual wateq4f saturation index exceeds 0 8 and are slightly below 0 7 calcium carbonate impregnation of cyanobacterial sheaths has not been observed we infer that in these fast flowing streams cyanobacteria utilize co2 in photosynthesis whereas elsewhere in sluggish freshwater cyanobacteria utilize hco3 leading to sheath impregnation by calcium carbonate even where saturation index is only 0 2 0 3 thus photosynthetic influence on cyanobacterial calcification appears to be negligible in fast flowing co2 rich streams and cyanobacterial calcification takes the form of external encrustation in slow flowing co2 poor streams and lakes cyanobacteria preferentially utilize bicarbonate and sheath impregnation can result modern tropical marine carbonate shelves have saturation indices commonly in the range 0 62 0 82 and cyanobacterial calcification is negligible extrapolation suggests that cyanobacterial calcification could occur in present day seas if saturation index exceeded 0 8 this level corresponding with heavy calcification in the freshwater streams studied may have been widespread in marine environments in the geological past at times when calcified cyanobacteria and environmentally influenced non skeletal calcium carbonate precipitates were abundant

depositional properties and geochemistry of holocene perched springline tufa deposits and associated spring waters a case study from the denizli province western turkey the guney waterfall area is a perched springline tufa site developed on the southeast slope of the buyuk menders river near guney town in the denizli province western turkey the site is away 12 km from the town and 72 km from the city center of denizli the spring waters emerge from the boundary between palaeozoic marble and micaschist and precipitated tufa deposits downslope at the altitudes ranging from 220 to 400 metres the tufa deposits cover an area of about 20 hectars flat upper surfaces of the deposits are indicative of mature stage the waters are of the ca hco3 type and supersaturated with respect to caco3 the stable isotope values of the spring waters are 49 94 for 2h and 7 15 for 18o the 13c and 18o values of active and passive tufa samples are in the range from 9 13 to 6 0 and from 8 44 to 7 40 respectively these isotopic values are typical for fresh water tufa the passive tufas give the 14c age in the range from 2000 to 5800 yr bp according to the 14c age data passive tufas are not older than holocene the stable isotope composition is similar south european examples

late pleistocene holocene palaeoenvironmental evolution of the anamaza river valley iberian range ne spain multidisciplinary approach on the study of carbonate fluvial systems abstract the uppermost pleistocene and holocene palaeoenvironmental evolution of the anamaza river valley iberian range ne spain is deduced using multidisciplinary approach including stratigraphical mineralogical palynological geochemical geophysical methods and drilling main changes were registered in distinct subenvironments of a carbonate fluvial system including the channelled zone and wetlands in the floodplain tufa barrages dominated although pools also existed geophysical survey and coring reveal tufa build ups and pool facies also in the subsoil lower water temperature and scarce evaporation are deduced for the pleistocene fluvial system that progressively changed through the holocene with more hydrologically closed areas and higher evaporation influence a general aggrading evolution during warm stages related with increasing base level and damming due to fast carbonate precipitation characterised the holocene detrital tufa indicates erosive high energy floods or colder stages when water level would decrease favouring erosion 14 c and 230 th 234 u dating reveal high sedimentation rates and three main discontinuities related with cold episodes younger dryas middle part of the holocene climate optimum and iron age epoch during the uppermost pleistocene tufa growth would be enhanced during warmer episodes as the bolling allerod in the younger dryas scarce vegetation favoured erosion of both slopes and tufa constructions subsequent warmer temperatures during the first part of the holocene favoured vegetated slopes enhanced tufa growing although interrupted in the middle part of the holocene climate optimum and development of wetlands with riparian vegetation in the floodplain where either siliciclastics or detrital tufa incoming alternated with low energy waters stages and mud settling progressive decline in tufa is deduced for the upper holocene but it is not possible to determine whether this and other palaeoenvironmental changes were related either to climate or increasing human activities during the roman and medieval warm periods more oxidizing conditions in the wetlands and increasing erosion prevailed probably conditioned by human activities the pollen record shows for the early holocene development of pinus forest with betula and expansion of deciduous quercus xerophilous and heliophilous grassland subsequent increasing moisture supported open forests with deciduous quercus ulmus corylus and evergreen quercus ilex pistacia species from ca 4000 yrbp a dominant deciduous quercus forest with groves of corylus ulmus acer fagus and taxus expanded and human activities grazing occurred from 1200 yrbp dry grassland expanded due to intensive land use agropastoral activities almost completely deforested plateaus surround the site today with slopes covered by patchy grass with junipers groves and screeds with little soil

the chi chi earthquake sequence active out of sequence thrust faulting in taiwan we combined precise focal depths and fault plane solutions of more than 40 events from the 20 september 1999 chi chi earthquake sequence with a synthesis of subsurface geology to show that the dominant structure for generating earthquakes in central taiwan is a moderately dipping 20 to 30 thrust fault away from the deformation front a second subparallel seismic zone lies about 15 kilometers below the main thrust these seismic zones differ from previous models indicating that both the basal decollement and relic normal faults are aseismic

the deep structure of south central taiwan illuminated by seismic tomography and earthquake hypocenter data abstract the taiwan mountain belt is generally thought to develop above a through going basal thrust confined to within the sedimentary cover of the eurasian continental margin surface geology magnetotelluric earthquake hypocenter and seismic tomography data suggest however that crustal levels below this basal thrust are also currently being involved in the deformation here we combine seismic tomography and earthquake hypocenter data to investigate the deformation that is taking place at depth beneath south central taiwan in this paper we define the basement as any pre eocene rifting rocks and use a p wave velocity of 5 2 km s as a reference for the interface between these rocks and their sedimentary cover we found that beneath the coastal plain and the western foothills clustering of hypocenters near the basement cover interface suggests that this interface is acting as a detachment this detachment is located below the basal thrust proposed from surface geology for this part of the mountain belt inherited basement faults appear to determine the geometry of this detachment and their inversion in the alishan area result in the development of a basement uplift and a lateral structure in the thrust system above them however across the shuilikeng and the chaochou faults earthquake hypocenters define steeply dipping clusters that extend to greater than 20 km depth above which higher velocity basement rocks are uplifted beneath the hsuehshan and central ranges we interpret these clusters to form a deeply penetrating east dipping ramp that joins westward with the detachment at the basement cover interface it is not possible to define a basal thrust to the east beneath the central range

the late holocene tufa decline in europe over much of europe it has been postulated that in the late holocene since c 2500 bp there was a marked decline in the deposition of tufa there has been considerable debate about the causes of this phenomenon with some authors postulating the importance of natural climatic changes and others asserting that miscellaneous human influences have been crucial this article discusses the role that various changes both natural and anthropogenic may have played and suggests ways in which the large number of possible hypotheses can be tested

how fast does tufa grow very high resolution measurement of the tufa growth rate on artificial substrates by the development of a contactless image based modelling device

recognition and implications of eocene tufas and travertines in the chadron formation white river group badlands of south dakota there are few descriptions of pre quaternary tufa or travertine yet these deposits have important climatic hydrological and tectonic implications in the badlands of south dakota the late eocene chadron formation contains a variety of tufa fluvial lacustrine paludal and perched springline types travertine and calcrete pedogenic and non pedogenic types in fluvial channels tufas and tufa barrages oncolites tufa lithoclast conglomerates and phytoherms are transitional to travertines pseudostromatolitic boundstone gravels and small pinnacle resurgences with rimstone edges and pools lacustrine tufas formed in small ponds adjacent to other types of tufas and are similar to the low energy bench margin facies types observed in modern groundwater fed temperate zone hardwater lakes paludal tufas are laterally discontinuous sheets of pisoid intraclast wackestone that fill palaeotopography distal perched springline tufas are mounds of numerous sloping tufa sheets concretions and rhizoliths associated with palaeosols are recognized as pedogenic calcretes whereas non pedogenic calcretes are variably cemented vertically oriented conduits for palaeogroundwater discharge that are located in fault zones these deposits resulted from palaeogroundwater discharge along faults during the late eocene coeval unroofing of the black hills uplift created a regional groundwater flow system through karsted palaeozoic limestones exposed in the black hills the chadron formation is an avulsion dominated siliciclastic unit yet important bodies of carbonate accumulated in it as a result of groundwater processes

the chemical evolution of a travertine depositing stream geochemical processes and mass transfer reactions this field study focuses on quantitatively defining the chemical changes occurring in falling spring creek a travertine depositing stream located in alleghany county virginia the processes of co sub 2 outgassing and calcite precipitation or dissolution control the chemical evolution of the stream the observed chemical composition of the water was used with the computerized geochemical model wateqf to calculate aqueous speciation saturation indices and co sub 2 partial pressure values mass balance calculations were performed to obtain mass transfers of co sub 2 and calcite reaction times estimated from stream discharge were used with the mass transfer results to calculate rates of co sub 2 outgassing and calcite precipitation between consecutive sampling points the stream which is fed by a carbonate spring is supersaturated with respect to co sub 2 along the entire 5 2 km flow path outgassing of co sub 2 drives the solution to high degrees of supersaturation with respect to calcite metabolic uptake of co sub 2 by photosynthetic plants is insignificant because the high supply rate of dissolved carbon dioxide and the extreme agitation of the stream at waterfalls and rapids causes a much greater amount of inorganic co sub 2 outgassing to occur calcite precipitation is kinetically inhibited until near the crest of amore 20 m vertical waterfall calcite precipitation rates then reach a maximum at the waterfall where greater water turbulence allows the most rapid escape of co sub 2 physical evidence for calcite precipitation exists in the travertine deposits which are first observed immediately above the waterfall and extend for at least 1 0 km below the falls net calcite precipitation occurs at all times of the year but is greatest during low flow conditions in the summer and early fall less

detrital input to spring fed fen deposits a problem or an opportunity in palaeoenvironmental studies a holocene palaeoclimatic reconstruction from central europe detrital input to spring fed fen deposits

unusual isotopic phenomena in welsh quarry water and carbonate crusts modern terrestrial speleothem like calcareous deposits in streams draining a disused lime quarry on black mountain south wales have anomalously negative d18o and d13c compositions compared with other similar european deposits black mountain water chemistry is unusual only in its locally very high ph 11 5 and carbonate ion concentrations the high ph is caused by dissolution of lime spoil resulting in high oh concentrations this high alkalinity causes uptake of atmospheric co2 and strong fractionation of both carbon and oxygen stable isotopes resulting in calcite precipitates with unusually negative isotopic compositions since shifts in d18o of 1 are highly significant for holocene palaeoclimate reconstructions depletions caused by hyperalkaline waters must be avoided while extreme lime spoil contamination should be obvious less heavily affected sites will record smaller fractionation effects and might escape detection even small depletions from low level contamination will have large effects on palaeotemperatures based on carbonate crust d18o values

cyclic variations of uranium concentrations and oxygen isotopes in tufa from the middle miocene barstow formation mojave desert california uranium concentrations of 42 to 169 ppm in fibrous calcite from spring deposited tufa in the middle miocene barstow formation california are among the highest reported for calcite fission track maps of multiple bands of uniformly dull luminescent fibrous calcite show that the concentration of u increases in the outward growth direction of the calcite of each individual band homogeneous dull luminescence in the fibrous calcite indicates no change in redox conditions of the fluid from which the calcite was precipitated it is proposed that the cyclic pattern of increase in u concentration reflects a cyclical change in the u ca ratio in the fluid episodic mixing between ca rich spring water with a low u ca ratio and ca poor saline alkaline lake water with a high u ca ratio could produce the episodes of formation of fibrous calcite with increasing u concentrations the spring water supplies the ca for calcite precipitation and the u concentrations increase with the decreasing fraction of spring water and increasing fraction of lake water these cycles reflect a variable recharge of groundwater into the lake by springs the large variation in u concentrations suggests mixing of 0 to 45 spring water with the lake while the narrow range in 18 o of 6 37 to 6 87 limits the variation of the proportions of spring and lake water to 5

continuous 60 year stable isotopic and earth alkali element records in a modern laminated tufa jaruga river krka croatia implications for climate reconstruction abstract a continuous 60 year record 1938 1998 of stable isotope compositions of carbon and oxygen as well as trace metal mg sr ba concentrations in a laminated calcite crust precipitated in a short artificial tunnel on a non equilibrium groundwater fed karstic river is presented chemical and isotopic records have been compared to hydrometeorological data available for the last 48 years an attempt is made to relate isotopic and geochemical variations in the crust to environmental parameters such as temperature precipitation and changes in vegetation cover as well as to postdepositional recrystallisation of the older crust material isotopic composition of the crust is largely influenced by non equilibrium precipitation which favours the incorporation of isotopically depleted c and o into the carbonate furthermore because of the complicated hydrological situation there is no observable correlation between the stable oxygen isotope composition of water and temperature the result is that the 18 o isotopic thermometers overestimate the measured precipitation temperatures temperatures calculated from mg ca ratios of water and the carbonate match the 18 o palaeotemperatures within 2 4 c in the older part of the crust precipitated before the onset of industrial pollution of the river it was demonstrated that the application of mg palaeothermometry in natural systems where the mg ca ratio of water is influenced not only by temperature but also by other environmental parameters such as precipitation surface runoff groundwater retention time and anthropogenic influences is subject to a large uncertainty up to 10 c

velocity field of gps stations in the taiwan area abstract the 131 stations of the taiwan gps network were surveyed 4 6 times from 1990 to 1995 with dual frequency geodetic receivers the standard deviation of an observed baseline length with its linear trend removed is in the range of 6 10 mm for a 3 120 km long baseline the average rates of length change for all baselines of the network and those from nine continuously monitoring permanent stations are used in a least squares adjustment to estimate the velocities of the gps stations relative to paisha penghu situated at the chinese continental margin to the south of fengping in the northern coastal range the velocity vectors of stations in lanhsu lutao and the coastal range trend in the directions of 306 322 with rates of 56 82 mm yr in contrast there is a dramatic decrease in the rates to the north of fengping this may be caused by the motion along the ne sw trending thrusts which obliquely cut the northern coastal range a discontinuity of about 30 mm yr in the rates along with a remarkable change in the directions of station velocity is observed across the longitudinal valley then the moving directions gradually shift to the west for the stations in the western foothills in the kaohsiung pingtung coastal area the station velocities are even directed toward the southwest to the north of the peikang high the velocity vectors of the stations change direction from the west gradually to the north and finally to the east and southeast significant nw se extensional deformation is found in the ilan plain and northern taiwan in general the pattern of the velocity field for gps stations in the taiwan area is quite consistent with the directions of present day tectonic stress

revealing surface deformation of the 1999 chi chi earthquake using high density cadastral control points in the taichung area central taiwan the 1999 chi chi earthquake m w 7 6 ruptured a major thrust fault along the western foothills of the central mountain range of taiwan here we use cadastral control points to detect horizontal displacement in taichung central taiwan the cadastral control points were used to identify the coordinates of buildings and acreage the coordinates of each point are measured by total station and connected to global positioning system gps control points the density of these control points is nearly 36 points km2 and the accuracy of each point is within less than 2 3 cm the government of taiwan measured cadastral control points before and after the chi chi earthquake in the taichung area northern end of the chelungpu fault 1269 control points were measured over a 35 km2 area with most control points being located on the hanging wall of the chelungpu fault on the footwall the displacement is about 1 1 1 2 m toward 123 to 128 which is consistent with gps data at the hanging wall the displacement direction concentrates at 326 to 330 in the eastern section the displacement is from 7 5 to 8 m which is consistent with gps and strong motion data but in the western part displacement changes from 8 m to 4 6 m and then increases again to 8 m along the 326 trending we conclude that the changes in displacements were controlled by the geometry of the fault plane online material horizontal displacement of cadastral control points

classification and environmental models of cool freshwater tufas abstract tufa deposits are common in the quaternary record facies developments are dependent upon localised carbonate precipitation generally these take the form of phytoherm build ups together with associated detrital deposits derived from disagragation of the former phytoherm cements differ from speleothems and floe calcite accumulations in being biologically mediated or modified this paper recognises the following five types perched spring line cascade fluviatile paludal and lacustrine facies each type is composed of distinctive constructional and detrital sediment associations these unique sediment combinations are the product of an interplay between angle of slope water discharge rate standing water bodies phytal and microbial colonization and ambient temperature the proposed models will be of value in the interpretation of ancient and partially exposed tufas

temperate and semi arid tufas in the pleistocene to recent fluvial barrage system in the mediterranean area the ruidera lakes natural park central spain abstract the ruidera lakes natural park in central spain contains a well exposed pleistocene to recent freshwater carbonate tufa succession dominated by fluvial barrages and lacustrine deposits the majority of exposed tufas are holocene to recent in age today carbonate accumulation is currently manifested as active phytoherm barrage constructions marginal lacustrine stromatolitic terraces lacustrine lime muds all produced mainly by precipitation and sand size detrital tufa the depositional history of the ruidera park sites has been interpreted from natural outcrops rotary drill and percussion auger cores these reveal a long quaternary record of microbially dominated barrage framework developments and associated lacustrine carbonates these alternate with frost weathering deposits and detrital tufa episodes especially during cooler conditions u series dating of several earlier tufa deposits within the park indicates four distinct episodes of tufa development at 190 250 ka b p 90 130 ka b p 30 40 ka b p and 16 ka b p present the three oldest episodes appear to be related to cyclic tufa building events associated with warm periods of oxygen isotope stages ois 7 5 and 3 growth under present conditions is slow and several barrages have been damaged by human activity and drought events

great earthquakes in low strain rate continental interiors an example from se kazakhstan the lepsy fault of the northern tien shan se kazakhstan extends e w 120 km from the high mountains of the dzhungarian ala tau a subrange of the northern tien shan into the low lying kazakh platform it is an example of an active structure that connects a more rapidly deforming mountain region with an apparently stable continental region and follows a known palaeozoic structure field based and satellite observations reveal an 10 m vertical offset exceptionally preserved along the entire length of the fault geomorphic analysis and age control from radiocarbon and optically stimulated luminescence dating methods indicate that the scarp formed in the holocene and was generated by at least two substantial earthquakes the most recent event dated to sometime after 400 years b p is likely to have ruptured the entire 120 km fault length in a m w 7 5 8 2 earthquake the lepsy fault kinematics were characterized using digital elevation models and high resolution satellite imagery which indicate that the predominant sense of motion is reverse right lateral with a fault strike dip and slip vector azimuth of 110 50 s and 317 343 respectively which is consistent with predominant n s shortening related to the india eurasia collision in light of these observations and because the activity of the lepsy fault would have been hard to ascertain if it had not ruptured in the recent past we note that the absence of known active faults within low relief and low strain rate continental interiors does not always imply an absence of seismic hazard

carbonate deposition in an ephemeral siliciclastic alluvial system jurassic shuttle meadow formation newark supergroup hartford basin usa abstract nonmarine carbonate accumulation from a sedimentologic perspective has multiple possible origins clastic load springs groundwater discharge soil development biochemical seasonal changes cave speleothems and eolian influx many of these carbonates contain diagnostic textures from which origin is easy to ascertain however differentiating between clastic and spring groundwater carbonates especially in depositional systems dominated by siliciclastics is not always simple here criteria for recognition are developed subsurface hydrology and tectonic origin of the depositional basin source rocks surrounding the basin sedimentologic packaging and extent of the carbonates in question as well as their sedimentary structures and fossil content and stable isotopic analyses of the carbonates can all aid in determining carbonate origin and correctly assessing sedimentary and basin evolution the present study focuses on a nonmarine carbonate deposit found within the jurassic shuttle meadow formation of the hartford basin one of many rift basins which formed as a result of the opening of the north atlantic ocean during the late triassic to early jurassic the upper 50 m of the formation at plainville connecticut is interpreted as continental in origin and is composed of five facies red ripple cross laminated muddy siltstones to sandstones fr sr massive red siliciclastic mudstones fm buff fine to medium grained horizontally laminated sandstones sh red to white disrupted calcareous shales fl3 and rare micritic carbonates pm facies fr sr sh and fm are interpreted as an alluvial plain system in an ephemeral setting with bedload sheetflooding as the dominant depositional mechanism similar to the channel country drainage system of central australia in addition preservation of lateral accretion sandstone sheets accretionary benches indicate that the shuttle meadow alluvial system was rapidly accreting the anomalous existence of carbonate beds in facies fl3 and pm in the smf bedload dominated siliciclastic sequence is attributed mainly to the unique nature of the clastic sediment load in the basin no direct evidence for a spring groundwater input is apparent the shallow carbonate lake margin or a pond with vegetation and periodic exposure is envisioned as the depositional environment the intraclastic texture of the micrites with rare primary relict lamination indicates early diagenetic alteration from root penetration desiccation cracks and burrowing

morpho stratigraphic characterization of a tufa mound complex in the spanish pyrenees using ground penetrating radar and trenching implications for studies in mars abstract the isona tufa mound complex itmc associated with artesian springs of the areny montsec aquifer spanish pyrenees is a potential analog for water constructed landforms on mars we used ground penetrating radar gpr trenching sedimentological description of exposures and radiocarbon and u series dating methods for the geological characterization of the itmc preliminary geomorphological mapping combined with sedimentological analyses permitted the recognition of the different facies and their spatial distribution gpr surveys conducted next to an outcrop and a trench provided electromagnetic wave velocity in tufas 0 09 and 0 11 m ns 1 and determined the correspondence of the radar signatures with facies types this was used to reconstruct the tufas internal structure and the depositional stages for two different contexts 1 an upper unit representing the morpho stratigraphic record of paleosprings tufa 1 composed of relict tufa mounds older than 350 ka bp and 2 a lower unit tufa 3 associated with groundwater aquifer outlets basturs lakes the gpr data allowed depicting the signatures for the vent pool rimstone palustrine dam cascade and slope facies a relationship was inferred between the age of the tufas and the radar signature in terms of relative amplitude and signal attenuation older dry tufas with advanced diagenesis and karstification are characterized by well defined gpr reflectors and lower attenuation than younger tufas associated with aquifer discharge and shallower water tables u series and radiocarbon ages obtained from the basturs lakes tufas indicate that these have been active since 106 ka bp during both cold and mild marine isotopic stages mis we hypothesize that tufas related to the deep seated areny montsec confined karst aquifer were insensitive to climate variations landforms reminiscent of the itmc have been detected during the last decade on mars since gpr will be part of the exomars rover of the european space agency esa mission projected for 2018 we anticipate that our results may be able to constrain the interpretation of landforms possibly related to water on mars

microbial carbonates as indicators of environmental change and biotic crises in carbonate systems examples from the late devonian alberta basin canada microbial precipitation of calcium carbonate has played a vital role in the development of carbonate platforms since their initiation in the proterozoic we report here the varied roles that microbial carbonates played in late devonian carbonate platforms in the alberta basin canada we recognize microbial carbonates as important contributors within the carbonate system during times of major environmental change including transgressive events in platform environments and the recovery interval following the frasnian famennian mass extinction detailed sequence stratigraphic analysis of two isolated platforms in the canadian rockies was used to document their evolution from a regional ramp to isolated platforms with phases of progradation aggradation and backstepping and renewed progradation related to rates of second order and third order sea level change and basin infill the carbonate system was reorganized following annihilation of many carbonate producing biota during the frasnian famennian mass extinction microbial carbonates figure prominently in both frasnian platform development and the famennian recovery of the carbonate system following the frasnian famennian mass extinction during transgressive platform phases deeper water facies with a crinoid rugose coral and microbe dominated biota abruptly overlie prograding stromatoporoid framestones microbial carbonates consist of abundant girvinellid oncoids that nucleated around other fossil clasts the temporary replacement of stromatoporoid communities during transgression implies a shift from oligotrophic to mesotrophic conditions and the microbes likely capitalized on the change in nutrient supply microbes played a significant role in highstand reef margin facies where renalcis was a binder and cementer in stromatoporoid framestones and downslope rugose coral stromatoporoid mounds microbially laminated carbonates also form stromatolitic mats in peritidal shallowing upward cycles and repetitive stromatolitic intervals commonly indicate sea level lowstands associated with the development of sequence boundaries stromatoporoid reefs and their associated reef interior facies indicate an oligotrophic ecosystem where microbial carbonates were relegated mainly to cryptic or stressed marine habitats an end frasnian sea level lowstand exposed the isolated carbonate platforms transgression and mass extinction characterize the frasnian famennian boundary event and microbial carbonates occur at this horizon in western canada stromatolites oncoids and large scale microbial thrombolites appear to be

evidence for azimuthal and temporal variations of the rupture propagation of the 1999 chi chi taiwan earthquake from dense seismic array observations data recorded by the smart 2 array and its nearby accelerometers in eastern taiwan were used to make direct measurements of the rupture propagation of the 1999 mw 7 6 chi chi taiwan earthquake the n th root stack method was employed to window and stack seismic waveforms and it revealed that coherent seismic energy showed clear temporal changes with regard to azimuth the results of this study elicited unambiguous observations as to rupture propagation direction rupture duration time and spatial distribution of the major asperities on the fault plane the rupture propagation of the chi chi earthquake was reconstructed and demonstrated that the source of the early arrived coherent energy was close to the epicenter and that the subsequent major energy moved southward twelve seconds after the initial rupture clear arrival energy was resolved and then propagated northward the horizontal apparent rupture velocity is estimated at 2 1 km sec for its northward propagation the largest source of radiated energy was identified and its location was near the northern end of the earthquake fault the strong shaking was continuous for about 24 seconds the analysed results of this study provide direct observations of the rupture properties of this earthquake these properties may serve as valuable constraints for other chi chi earthquake rupture propagation studies based on other indirect measurement methods

coseismic displacement bilateral rupture and structural characteristics at the southern end of the 1999 chi chi earthquake rupture central taiwan 1 the 1999 chi chi earthquake mw 7 6 was due to slip along the chelungpu fault a major n striking thrust fault in the fold thrust belt of western taiwan the surface rupture extends over 100 km in a n s trend with nw trending horizontal displacement increasing from 2 to 10 m from south to north the central segment of the chelungpu fault is characterized by bedding slip along the pliocene chinshui shale which has resulted in the development of a monoclinal structure on the hanging wall at the southern end of the chi chi earthquake rupture however the chelungpu fault connects with the ne striking tachienshan fault and cuts into miocene strata with complex structures on the hanging wall in this study we use digital cadastral data to calculate coseismic horizontal displacement around the chushan area results show the amount and direction of horizontal displacement to be ca 1 2 to 2 6 m and ca 220 to 260 respectively on the hanging wall and ca 1 4 m and 105 respectively on the footwall coseismic displacement and seismological data pertaining to the hanging wall at the southern end of the chi chi earthquake rupture indicate the existence of three distinct blocks horizontal displacement indicates the chushan block s movement trended sw this result reflects the chushiang and luliao faults being reactivated with different faulting mechanisms and slip azimuths this study considers a complex coseismic displacement field resulting from a bilateral rupture process whereby a southward rupture with sw trending movement results in right lateral strike slip faulting of the tachienshan fault and thrusting with a right lateral component on the ns strike of the chelungpu fault the northward rupture is associated with nw trending movement that results in activation of the luliao and chushiang faults

contrasting fault fluids along high angle faults a case study from southern apennines italy abstract this work focuses on two fault controlled deposits the atella and rapolla travertines which are associated with high angle extensional faults of the bradano trough southern apennines italy the atella travertine is along a nw se striking deep seated extensional fault already described in literature which crosscuts both apulian carbonates and the overlying foredeep basin infill the rapolla travertine is on top of a ne sw striking shallow seated fault here described for the first time which is interpreted as a tear fault associated with a shallow thrust displacing only the foredeep basin infill the results of structural sedimentological mineralogical and c and o isotope analyses are here reported and discussed to assess the provenance of mineralizing fluids and to evaluate the control exerted by the aforementioned extensional faults on deep mantle derived and shallow meteoric fluids sedimentological analysis is consistent with five lithofacies in the studied travertines which likely formed in a typical lacustrine depositional environment mineralogical analysis show that travertines mainly consist of calcite and minor quartz feldspar and clay minerals indicative of a terrigenous supply during travertine precipitation the isotope signature of the two studied travertines shows different provenance for the mineralizing fluids at the atella site the 13cpdb values range between 5 2 and 5 7 and the 18opdb values between 9 0 and 7 3 which are consistent with a mantle derived co2 component in the fluid in contrast at the rapolla site the 13cpdb values vary from 2 7 to 1 5 and the 18opdb values from 6 8 to 5 4 suggesting a mixed co2 source with both biogenic derived and mantle derived fluids the results of structural analyses conducted along the footwall damage zone of the fault exposed at the rapolla site show that the whole damage zone in which fractures and joints likely channeled the mixed fluids acted as a distributed conduit for both fault parallel and cross fault fluid migration

freshwater phytoherm reefs the role of biofilms and their bearing on marine reef cementation abstract bioconstructions in carbonate rich freshwater environments generally lead to the development of thick autochthonous tufa deposits in rivers systems these large plant dominated freshwater reef frameworks phytoherms are capable of damming the water courses to produce chains of lakes the resulting phytoherms profoundly modify both local environment and sedimentation patterns in their vicinity and provide a wide range of niches for biota subaqueous fringe cements coat all exposed surfaces they bind the ephemeral plant frameworks providing a cement framework and give rigidity to the bioconstructions peloids are intimately associated with the development of these cements and frequently infil intra reef and framework cavities evidence is presented to suggest that both micritic fringe cements and peloids are the product of biological mediation associated with a procaryote microphyte biofilm and the presence of organic detritus the bladed low magnesium calcite fringes which develop subsequently on the micrite fringes and peloids are possibly slower formed inorganic precipitates the close morphological similarities between phytoherm fringe cements and peloids and their marine reef counterparts are considered to be more than coincidental it is argued that procaryote microphyte biofilms are also responsible for micritic precipitates in the shallow photic marine realm with bacterial films possibly carrying the process deep into unlit reef cavities and conduits and deep water lithoherms

pollen and mollusc records for environmental change in central spain during the mid and late holocene the central part of the iberian peninsula has few radiocarbon dated records of vegetation and climatic history for the holocene extinct and active tufa forming sites occur along the northwestern margin of the sierra de alcaraz tufas are often closely associated with the remains of plants and animals and two extinct systems near the settlements of el jardin and alcaraz have yielded a record of environmental history that spans much of the last 6000 years the record indicates that the present day sedimentological regime and vegetation are human induced and probably extend back to about 2700 yr bp before this date oak dominated scrub mattoral was widespread prior to around 5000 yr bp the climate appears to have been relatively humid and possibly cooler and the catchments for the two sites were more wooded than today

can 234u 230th dating be used to date large semi arid tufas challenges from a study in the naukluft mountains namibia the large extensive tufa deposits of the semi arid naukluft mountains namibia are potentially important palaeoenvironmental indicators in an area with few proxy records tufas are reliable indicators of increased moisture availability and have been shown to be amenable to 234u 230th dating although two challenges are detrital contamination and open system behaviour densely cemented tufa facies are good candidates for dating minimising these problems we report attempts to date five densely cemented units which are only found rarely within the naukluft deposits we applied a detailed methodology using multiple subsample analysis measurement of insoluble residues application of isochron mixing lines and attempted open systems modelling alongside observations of micromorphology and cathodoluminescence in order to assess the validity of any obtained dates surprisingly densely cemented tufas were found not always to be suitable for dating two units contained detrital contamination which could not be corrected for using a single leachate correction or isochron methods two units contained excess 230th this could result under a closed system if initial 234u 238u was sufficiently high alternatively this may be the result of open system behaviour and loss of uranium or incorporation of initial unsupported 230th which render samples unsuitable for 234u 230th dating micromorphological appearance and cathodoluminescence behaviour are used to explore these possibilities this study exemplifies the need for careful sample selection and highlights the importance of analysing multiple subsamples from any tufa sample the detailed methodology applied proves to be a powerful tool for identifying the range of problems that can be encountered when selecting suitable candidate samples for successful dating it also shows that semi arid tufa sequences may contain very little material suitable for dating a reliable age of c 80 ka was obtained for a banded unit within a large fluvial barrage with less reliable dates suggesting tufa deposition during times since 350 ka through to the late holocene copyright 2010 john wiley sons ltd

revealing coseismic displacements and the deformation zones of the 1999 chi chi earthquake in the tsaotung area central taiwan using digital cadastral data 1 the 1999 chi chi taiwan earthquake mw 7 6 was the largest earthquake to strike taiwan in the twentieth century this earthquake is associated with a 100 km long surface rupture in order to reveal the details of displacement near the surface rupture we use a digital cadastral system to calculate coseismic displacement around the tsaotung area central taiwan the digital cadastral system was originally conceived to survey land and building boundaries in the tsaotung area taiwan authorities have taken digital cadastral measurements before and after the chi chi earthquake the cadastral system affords high density control points that reach 1421 points km2 a system denser than that of the gps accuracy is to within 11 cm a level that is higher than spot imaging and one that allows us to study surface deformation in detail coseismic displacement is 4 3 4 6 m at distance from the surface rupture and decreases to 3 4 m near the surface rupture the azimuth of horizontal displacements is 310 315 and rotates to 280 305 near the surface rupture this produced a compression left lateral deformation zone with 10 3 compression strain near the surface rupture coseismic displacement of the footwall is 1 1 2 m in 110 which is similar to that from using gps data in the tsaotung thrust slice we observed that the azimuth of horizontal displacement rotates from a nw trend to a south trend as a result of slip partitioning and gravity slide effect

slip vectors of the surface rupture of the 1999 chi chi earthquake western taiwan about 100 slip vectors were surveyed along the 1999 chi chi earthquake rupture 100 km long western taiwan to understand the coseismic reverse faulting processes the surveyed slip azimuths vary locally over 80 where the rupture is irregular or associated with flexure even where the rupture is straight and has consistent slip azimuths the fault scarp heights horizontal slips and fault dip angles oscillate in a distance of hundreds of meters along the rupture despite these local variations the net slip up to 11 5 m vertical and horizontal slips are significant greater in the north on which maximum shortening 6 m by pure thrust and strike slip 8 m by left lateral fault occur in association with the bend of the rupture the slip azimuths also progressively rotate from north northwest in the north to west southwest in the south these patterns generally agree with those revealed by gps surveys except that the slips by gps in the south move to the west northwest and have values unexpectedly smaller than our measurements our obtained sw directed slips resulted in dominantly right lateral faulting up to 2 4 m where the rupture ends to the southeast this however does not correspond to focal mechanisms of any main shocks or aftershocks

lacustrine carbonates of iberian karst lakes sources processes and depositional environments abstract carbonates are the main components of iberian quaternary lake sediments in this review we summarize the main processes controlling carbonate deposition in extant iberian lakes located in mesozoic and tertiary carbonate dominated regions and formed through karstic activity during the late quaternary the lakes relatively small 1 ha to 118 ha and relatively shallow zmax 11 to 40 m provide examples of the large variability of sedimentary facies depositional environments and carbonate sources hydrology is dominated by groundwater inflow except those directly connected to the fluvial drainage nine lakes have been selected for this review and the main facies in palustrine littoral and profundal environments described and interpreted clastic carbonates occur in all iberian lakes due to the carbonate composition of the bedrocks surface formations and soils of the watersheds low temperatures and dilute meteoric waters seem responsible for the low carbonate content of sediments in high elevation lakes in the glaciated terrains in the pyrenees and the cantabrian mountains clastic carbonates are dominant in small karst lakes with functional inlets where sediment infill is dominated by fining upward sequences deposited during flood events re working of littoral carbonates is common in shallow environments and during low lake level stages in most lakes endogenic carbonate production occurs in two settings i littoral platforms dominated by chara and charophyte meadows and ii epilimnetic zone as biologically mediated calcite precipitates continuous preservation of varves since the mid holocene only occurs in one of the deeper lakes montcortes lake up to 30 m where calcite laminae textures massive fining upward and coarsening upward reflect seasonal changes in limnological conditions however varves have been formed and preserved in most of the lakes during short periods associated with increased water depth and more frequent meromictic conditions most iberian lakes are in a mature stage and karstic processes are not very active an outstanding example of a lake with intense karstic activity is banyoles lake where increased spring discharge after long rainy periods causes large remobilization and re suspension of the sediments accumulated in the deepest areas leading to the deposition of thick homogeneous layers homogeinites the iberian karst lake sequences underline the large variability of facies carbonate sources and depositional environments in small lake systems they illustrate how lake types evolve through the existence of a lake basin at centennial or even smaller time scales hydrology is the paramount control on facies and depositional environment patterns distribution and lake evolution and consequently a lake classification is proposed based on hydrology and sediment input a correct interpretation of carbonate sources and depositional history is a key for using lake sequences as archives of past global changes

fluvial diffluence episodes reflected in the pleistocene tufa deposits of the river piedra iberian range ne spain abstract the pleistocene deposits of the valley of the river piedra ne spain are represented by thick tufas with small amounts of detrital material the development of these deposits correlates with marine isotopic stages 9 7 6 and 5 the sedimentary scenario in which they formed mostly corresponded to stepped fluvial systems with barrage cascade and associated dammed areas separated by low gradient fluvial stretches mapping and determining the sedimentology and chronology of these deposits distinguished two main episodes of fluvial diffluence that originated as a result of the temporary blockage of the river a consequence of the vertical growth of tufa barrages in the main channel in both episodes water spilt out toward a secondary course from areas upstream of barrages where the water level surpassed the height of the divide between the main and secondary course as a consequence extensive and distinct tufa deposits with very varied facies formed over a gently inclined area toward and indeed within the secondary course the hydrology of this secondary course was episodic fed only by surface water the two diffluence episodes detected occurred during mis 7 and 7 6 and were interrupted by incision events reflected by detrital deposits at the base of each tufa sedimentation stage in the main channel incision which caused the breakage of the barrages allowed water to again flow through the main channel no evidence of diffluence was seen in any younger mis 5 to present day tufa deposits the proposed diffluence model might help explain other carbonate fluvial systems in which 1 tufas appear in areas with no permanent water supply and 2 tufas are absent over extensive areas despite conditions favourable to their formation

are current models of tufa sedimentary environments applicable to tropical systems a case study from the gregory river abstract tufa formation in the gregory river tropical northern australia is strongly influenced by high evaporation rates perennially warm water temperatures construction behaviour of aquatic insect larvae and regular high magnitude floods these conditions contrast with those of the cool temperate tufa depositing streams for which sedimentary models have already been developed gregory river tufas occur as multiple series of dams separated by waterholes indicating that under all climatic conditions there is a persistence of hydraulic factors in controlling the dam pool sequence in fluvial tufa systems however at the scale of individual tufa deposits and facies the gregory river system displays a deviation away from current models tufa domes upstream dipping ramps calcite rafts and larval facies are all common and important features in both modern and fossil tufas of the gregory river but they are not included in current tufa models thus specific sedimentary models need to be developed for seasonally humid tropical tufa systems to understand their formation and interpret them correctly in the rock record

the taravilla lake and tufa deposits central iberian range spain as palaeohydrological and palaeoclimatic indicators 21 pages 8 figures 3 tables available online oct 13 2007 issue title lake systems sedimentary archives of climate change and tectonics egu general assembly

new insights into biological influence on the geochemistry of freshwater carbonate deposits abstract ambient temperature freshwater carbonates tufas have outstanding potential as palaeoclimate archives however it has proven difficult to constrain the behaviour of the geochemical parameters on which important proxy systems rely current thinking on the development of trace element ratios in tufa rests upon an assumption of precipitation driven by degassing of co2 with the final precipitate being in equilibrium with ambient river water this study provides evidence that although supersaturation is largely regulated by degassing precipitation in sterile flowing systems does not occur throughout the air water interface but only at lines of intersection between this interface and a solid surface precipitation at the bottom as is normal in river sites is not found to occur however when benthic microbial communities biofilms are present extensive precipitation does occur within them in preference and or addition to that at the air water interface precipitation is therefore not purely a consequence of degassing and some microbiological influence is necessary to generate precipitates analogous to nature we further investigate whether these biofilms alter the behaviour of trace elements within tufa systems in addition to modulating the sites and mechanisms of precipitation via a series of experiments biofilms are shown to accumulate large inventories of calcium and other dissolved ions ba sr and mg and we demonstrate that this process is chemoselective in favour of ions with low charge densities these observations have consequences for interpretation of trace element records from tufas based on an assumption of equilibrium with river water and also for other carbonate deposits associated with biofilm activity travertines marine stromatolites lacustrine and soil carbonates speleothems conversely our study provides new insight into the reasons for discrepancy of tufa mg ca ratios from expectation and thus provides encouragement for the potential of mg ca palaeothermometry in freshwater carbonate systems

sedimentation of holocene tufa influenced by the neolithic man an example from the sąspowska valley southern poland abstract a complex of inactive tufas the thickness of which reaches 3 5 m was studied in the lowermost segment of the s spowska valley in the krakow upland ojcow national park poland five fluvial tufa barrages were recognized they are composed of moss tufa and stromatolitic tufa accompanied with oncoidal rudstone and detrital tufa interbarrage ponded areas were filled with detrital tufa lutite and subordinately oncoidal rudstone limestone gravel and peat like deposit radiocarbon dates suggest that the tufa formed during subboreal boreal and atlantic time the main difference between the tufa in the s spowska valley and contemporaneous tufas in other valleys of the krakow upland is the higher amount of non carbonate fraction in the former other lower and middle holocene tufas of the krakow upland are composed mainly or exclusively of carbonate fraction the non carbonate fraction in fluviatile tufas in the s spowska valley resulted from erosion of loess cover in the upper part of the catchment the erosion was related to local activity of neolithic flint miners who cleared forest at a local scale dug shafts in loess cover and exploited flints from underlying weathered residuum of jurassic limestone consequently they made copious amounts of loose material available for transport down the valley and subsequent trapping within the tufa depositional system

fluid pressure stress field and propagation style of coalescing thrusts from the analysis of the 20 may 2012 ml 5 9 emilia earthquake northern apennines italy terra nova 25 72 78 2013 abstract two major earthquakes of ml 5 9 and 5 8 and hundreds of aftershocks affected the emilia region po plain italy between 20 may and june 2012 the events concentrate in the uppermost 10 km of the crust with few events up to 30 km two buried sub parallel n100 e striking thrusts of the northern apennines belt are reactivated these thrusts coalesce at the interface between the metamorphic basement of the belt and the overlying about 10 km thick sedimentary succession focal mechanisms indicate a compressive stress field with a sub horizontal roughly n s striking 1 this stress field is consistent with active shortening in northern apennines suprahydrostatic pore pressure and 1 2 3 are required to reactivate the thrusts the involved fluids could be gas and brines hosted in the folded sedimentary successions the time and spatial evolution of the seismicity indicates a foreland to hinterland propagation of the ruptures and a thin skinned deformation of northern apennines

red palaeosols sequence in a semiarid mediterranean environment region in this work we study one of the most palaeopedological sequence formed in central spain which is located on the pliocene pleistocene erosional surface in the madrid basin we also analyse its relationship to erosive and sedimentary pleistocene events in order to obtain new data for a correct interpretation of the origin and evolution of forms at the top of tabular lands in this site the geomorphic features and the properties of a sequence of very red palaeosols that developed on this old surface can help us in the understanding of the palaeoclimatic evolution of central spain in a mediterranean climate they were examined to identify pedologic and climatic changes during the quaternary the soil sequence comprises intercalated palaeoargillic and palaeopetrocalcic horizons the clay minerals are mainly illite kaolinite smectite and sepiolite the alternation of argillic and calcic horizons limestone debris cryoclastic colluvions and aeolian sands suggests succeeding periods of phytostability and phytoinstability biostasis rhexistasis argillation rubification and calcium carbonate accumulation were repeated throughout the pleistocene and it is hypothesised that climatic conditions during numerous stages of this period were not very different from the present conditions

multidisciplinary approach for palaeoclimatic signals of the non marine carbonates the case of the sarikavak tufa deposits afyon sw turkey abstract non marine carbonates such as travertine tufa and speleothem are quite sensitive for climatic fluctuations this study presents the new dating and the first pollen records from afyon sarikavak tufas sw turkey together with lithofacies descriptions geochemical and petrographic results obtained from drilling cores sl 2 sl 6 and sl 7 the data extensively provides insight into palaeoenvironmental and palaeoclimatic changes during the middle late pleistocene period according to core samples these fluvial tufa occurrences formed in high gradient and stepped fluvial conditions have been defined as barrage dammed and terraced slope systems in the investigated area the depositional lithofacies are moss tufa included macrophytes bryophytes and vertical stems phytoclastic tufa peloidal tufa micritic tufa microbial tufa intraclastic tufa extra formational tufa lime muddy clay and paleosol level in respectively the new u th radiometric dating and stable isotopes are evaluated together with previously published results in regard to new radiometric data tufa deposits occurred predominantly during the marine isotopic stages at 313 3 21 mis 9 295 8 63 mis 8 9 230 8 42 mis 7d e 228 8 12 mis 7d 215 7 17 mis 7c and 188 2 16 mis 6 7a ka respectively the climatic changes occurring between glacial and interglacial periods such as during the middle late pleistocene might probably influenced the precipitation of tufas in the area in addition the less negative and the more positive carbon isotopic values between 0 8 and 1 3 v pdb could be related to the progressive downstream co2 degassing from host rocks enhanced by high velocity current conditions changes in the soil co2 contribution and photosynthesis the changes of 18o values between 8 3 and 10 1 v pdb are most probably related to variable effects of evaporation in depositional environment palynofloral data gives important clues about the paleovegetation and paleoclimate of the region this field survey has been conducted the first time in this area both carbon values and palynological findings show that drought conditions were dominantly present in the pleistocene period but in some processes drought conditions decreased depending on the amount of rainfall the increasing amount of gymnosperm pollens is more likely to appear in more humid conditions due to the decreasing of drought condition in this time interval

fault rupture process of the 20 september 1999 chi chi taiwan earthquake we modeled the source rupture process of the 20 september 1999 chi chi taiwan earthquake mw 7 6 using an integrated dataset of near field strong ground motion and global positioning system observations this large inland thrust earthquake produced a surface break more than 80 km long along the chelungpu fault the event triggered over 700 strong motion instruments on the island of tai wan this large ground motion dataset provides the best opportunity to date to un derstand earthquake source processes in a major earthquake first we develop a 3d curved fault model consistent with the surface rupture data and aftershock distribu tion the subsurface fault plane has an average dip of 30 to the east and measures 96 km along strike and 40 km down dip next we applied a genetic algorithm to reconstruct the source rupture process the inversion results indicate a complex slip distribution with a generally broad triangular shaped slip zone that points down dip most of the displacement occurred over a 15 km depth range in the northern segment of the fault with the maximum slip exceeding 20 m the average slip is 3 8 m and the average rupture velocity is 2 6 km sec the mainshock slip distribution clearly complements the aftershock location distribution slip rise times range from 8 to 6 sec over most of the primary slip area and decrease slightly as rupture propagates south to north this relatively long rise time resulted in a low dynamic stress drop and low peak ground accelerations observed at surface stations the rake angle rotates across the rupture plane from predominantly dip slip in the southern segment to mostly left lateral oblique slip in the north we find that geometrical irregularities over the fault plane played an important role in controlling the temporal rupture behavior at fault bends rupture tends to decelerate the rake angle rotates to a near dip slip orientation and the shear stress increases as rupture tries to overcome the bending barriers the total seismic moment from our inversion is 2 9 10 27 dyne cm in good agreement with the harvard and the u s geological survey moment estimation

preseismic deformation and coseismic displacements associated with the 1999 chi chi taiwan earthquake the destructive 1999 chi chi taiwan earthquake m w 7 5 produced an approximately 100 km long surface rupture mostly along the previously recognized north south trending chelungpu fault preseismic deformation in central taiwan is realized from annually repeated global positioning system gps data acquired during the 1992 1999 period the total wnw ese shortening rate in the vicinity of the epicentral region that is from the west coast to the western boundary of the central range is up to 25 mm yr the crustal deformation before the chi chi earthquake was essentially a uniaxial compressional strain of 0 36 strain yr in the direction of 114 the gps measurements taken 0 2 2 7 yr before and within 3 months after the mainshock were utilized to estimate the coseismic displacements horizontal movements of 1 1 9 1 m in the nw nnw directions are observed on the hanging wall eastern side of the fault there is a northward increasing trend in the magnitude of the displacement vectors and a dramatic change in the direction of about 50 toward the east along the fault strike in contrast much smaller se see movements of 0 1 1 5 m are found on the footwall western side of the fault the gps data show 2 4 10 1 m of total horizontal offsets across the chelungpu fault vertical offsets of 1 2 4 4 m with the eastern side up are also observed along the surface rupture the uplift on the hanging wall decreases rapidly toward the east it becomes subsidence at sun moon lake and in the puli wushe area the stations on the footwall show subsidence of 0 02 0 26 m the width of the uplift zone increases from about 10 km in the south to approximately 30 km in the north manuscript received 13 october 2000

quaternary fluvial tufas of sarikavak area southwestern turkey facies and depositional systems abstract in the quaternary sarikavak fluvial tufa deposits situated in south western turkey different facies have been identified and their mutual relationships have been unravelled this tufa formation is located at the northern part of acigol graben the development of the sarikavak tufas represents typical fluvial and fluvio palustrine environments in total eight tufa lithofacies have been differentiated namely moss tufa facies oncolitic tufa facies stromatolitic tufa facies phytoclastic tufa facies intraclastic tufa facies extra formational clastic tufa facies sapropelitic tufa facies and palaeosol preliminary u th datings indicate that these deposits formed prior to 219 ka and continued until 80 ka mis 7 till 5 13c signatures 0 78 to 1 63 v pdb best can be explained by limestone dissolution processes or respiration from c4 plant vegetation into the soil or both for that reason the sarikavak tufa deposits can be classified as travitufa which precipitated in a distal facies system of travertine occurrences 18o values 7 49 to 10 83 v pdb of the whole data set reflect some significant changes which is interpreted in terms of temperature variations reflecting warm and cold periods among mis 7 interglacial mis 6 glacial and mis 5 interglacial the development of the sarikavak tufa deposits are related to the maymundagi fault that borders the acigol graben in the north this fault and its synthetic fault segments play a pivotal role with regard to the palaeo flow direction of water and control the basin topography these structural structures are likely responsible for all active and ancient springs in the study area as well as their respective carbonate precipitates

geomorphological identification of pre existing active chelungpu fault in central taiwan especially its relation to the location of the surface rupture by the 1999 chichi earthquake abstract pre existing active faults were identified on the chelungpu fault based on airphoto interpretation and field survey and their precise position was mapped active faults are divided into four types from i to iv depending on certainty of the presence of active faults and accuracy of their location most of the chelungpu fault shows evidence of late quaternary repeated activities the location of the 1999 chichi earthquake surface ruptures were plotted from the sites where they were accurately mapped by gps measurements by the central geological survey supplemented by our own observations on the active fault map there is a very close coincidence between the active fault trace and the 1999 surface rupture indicating that the mapping of active faults is fundamental for the estimation of location of rupture by future earthquakes

a review of the tagus river tufa deposits central spain age and palaeoenvironmental record here we determined the aminostratigraphy and aminochronology of tufa deposits located in central spain associated w i t h the tagus river and some o f its tributaries the henares dulce cifuentes ruguilla trabaque escabas and guadiela rivers w e used aspartic acid and glutamic acid racemization ratios obtained from the ostracod herpetocypris reptans tufa accumulations were found to be of different origins those in t h e henares cifuentes and ruguilla rivers are of paludal origin w h i l e those in t h e dulce and tagus rivers are o f fluvial origin a generally g o o d correspondence was found b e t w e e n the age o f the deposits and the position of the terraces above the current thalweg however the geomorphological evolution of the henares cifuentes and ruguilla rivers infilling of pre existing valleys has produced deposits of distinct ages at the same elevation above the current river thalweg and sometimes older tufas are located b e l ow younger ones we distinguished eight main tufa deposition episodes these occurred predominantly during even marine isotopic stages mis at 4 0 6 90 mis 11 2 6 4 68 mis 7e 189 4 0 mis 7a 130 27 mis 6 5e 101 2 5 mis 5c 3 2 10 mis 3 1 4 4 mis 1 a n d 6 2 mis l k a these results are in agreement w i t h the dating of similar deposits from nearby areas and other zones of s p a i n a n d europe the tufa stable isotope compositions were similar to other examples in central and southern spain a n d their plot falls in the same field as other lowland european stream tufas o x y g e n stable isotopes were influenced mainly b y temperature a n d rainfall the 51 3c values indicated a major effect o f soil derived carbon rather t h a n carbon from the catchment area but moderated in each tributary b y evaporation flow regime and biological effects photosynthesis

crossing forest thresholds inertia and collapse in a holocene sequence from south central spain a holocene palaeoecological sequence from villaverde south central spain is presented the pollen stratigraphy is used to infer past vegetation changes within a catchment area that represents the boundary between semi arid plateau and mountain vegetation from c 9700 7530 cal yr bp pinus is dominant probably as a result of a combination of a relatively dry climate and natural fire disturbance from c 7530 5900 cal yr bp moderate invasion by quercus appears to be a migrational response following increased moisture and temperature but in part shaped by competitive adjustments from c 5900 5000 cal yr bp the pine forests are replaced by deciduous quercus forests with an important contribution from corylus betula fraxinus and alnus mediterranean type forests spread from c 5000 to 1920 cal yr bp coincident with expansions of artemisia juniperus and other xerophytes from c 1920 1160 cal yr bp pinus becomes dominant after a disturbance mediated invasion of the oak forests human impact u

high potential of calcareous tufas for integrative multidisciplinary studies and prospects for archaeology in europe calcareous tufas are continental carbonates from open air conditions specific to wet and warm periods they contain abundant remains of fauna and flora fossilised in situ and may accumulate regularly over thousands of years offering high stratigraphic resolution for palaeoenvironmental reconstructions as they are mainly comprised of calcite tufas allow direct and precise dating as well as geochemical reconstructions of past climates additionally recent investigations have highlighted their strong potential for archaeology as several studied sequences provided high quality record of in situ prehistoric levels tufas are thus a unique archive in continental areas for development of synergic multidisciplinary investigations of past human societies and associated environmental and climate evolution we emphasise that calcareous tufa are key deposits to investigate human environment climate interactions during interglacial periods from lower palaeolithic to antiquity in europe

climatic and tectonic significance of late pleistocene and holocene tufa deposits in the mijares river canyon eastern iberian range northeast spain

c and o stable isotope variability in recent freshwater carbonates river krka croatia three types of recent carbonate precipitates from the river krka croatia were analysed 1 bulk tufa from four main cascades in a 34 km long section of the river flow through the krka national park 2 a laminar stromatolite like incrustation formed in the tunnel of a hydroelectric power plant close to the lowest cascade and 3 recent precipitates collected on artificial substrates during winter spring and summer periods stable isotope compositions of carbon d 13 c and oxygen d 18 o in the carbonate and organic carbon d 13 corg were determined and compared with d 18 o of water and d 13 c of dissolved inorganic carbon dic the source of dic which provides c for tufa precipitation was determined from the slope of the line dic dic0 1 vs d 13 c dic dic dic0 sayles curry 1988 the d 13 c value of added dic was 13ae6 corresponding to the dissolution of co2 with d 13 c between 19ae5 and 23ae0 vienna pee dee belemnite vpdb the observed difference between the measured and calculated equilibrium temperature of precipitation of bulk tufa barriers indicates that the higher the water temperature the larger the error in the estimated temperature of precipitation this implies that the climatic signals may be valid only in tufas precipitated at lower and relatively stable temperatures the laminar crust comprising a continuous record of the last 40 years of precipitation shows a consistent trend of increasing d 13 c and decreasing d 18 o the lack of covariation between d 13 c and d 18 o indicates that precipitation of calcite was not kinetically controlled for either of the elements d 13 c and d 18 o of precipitates collected on different artificial substrates show that surface characteristics both of substrates and colonizing biota play an important role in c and o isotope fractionation during carbonate precipitation

slip history and dynamic implications of the 1999 chi chi taiwan earthquake we investigate the rupture process of the 1999 chi chi taiwan earthquake using extensive near source observations including three component velocity waveforms at 36 strong motion stations and 119 gps measurements a three plane fault geometry derived from our previous inversion using only static data ji et al 2001 is applied the slip amplitude rake angle rupture initiation time and risetime function are inverted simultaneously with a recently developed finite fault inverse method that combines a wavelet transform approach with a simulated annealing algorithm ji et al 2002b the inversion results are validated by the forward prediction of an independent data set the teleseismic p and sh ground velocities with notable agreement the results show that the total seismic moment release of this earthquake is 2 7 10 20 n m and that most of the slip occurred in a triangular shaped asperity involving two fault segments which is consistent with our previous static inversion the rupture front propagates with an average rupture velocity of 2 0 km s 1 and the average slip duration risetime is 7 2 s several interesting observations related to the temporal evolution of the chi chi earthquake are also investigated including 1 the strong effect of the sinuous fault plane of the chelungpu fault on spatial and temporal variations in slip history 2 the intersection of fault 1 and fault 2 not being a strong impediment to the rupture propagation and 3 the observation that the peak slip velocity near the surface is in general higher than on the deeper portion of the fault plane as predicted by dynamic modeling

two middle pleistocene warm stages in the terrace deposits of the apulia region southern italy abstract we studied two middle pleistocene terraced deposits exposed along the trani cliff and at coppa nevigata in the apulia region southern italy in particular our study focused on stromatolitic units that are present at two sites at the trani cliff unit i consists of cemented whitish fine grained massive or bedded limestone the limestone grades upwards into massive porous bioconstructed calcareous bodies composed of in situ charophyta stems and or stromatolites the uppermost part of the unit is composed of whitish calcarenite calcisiltite layers with characeae the interpreted sedimentary environment for this unit is a hypersaline brackish lagoon at coppa nevigata the nvi unit is composed of tawny or yellow ochre sand with rare polygenic centimetric pebbles the sand grades upwards into light yellow and ochre sandy clayey silt or clay some layers are cemented and form marly limestones which contains columnar stromatolites the uppermost part of the unit consists of yellow ochre or tawny marly limestones and marls that are rich in external moulds of abra sp and cerastoderma glaucum the interpreted sedimentary environment for this unit is a brackish lagoon unit i and the nvi unit have been dated to mis 9 and mis 11 respectively by applying the amino acid racemisation aar method to ostracod shells the stromatolites of the nvi unit are ascribable to sh type whereas those of unit i are ascribable to sh and llh types and to colloform type in particular the stromatolites at the trani cliff are similar in shape and sedimentary environment to the modern stromatolites in shark bay australia the water temperature and salinity conditions under which the current stromatolites live indicate that tropical subtropical conditions were present in the mediterranean sea during mis 11 and mis 9 our reconstructions suggest that 1 during mis 11 the sea surface temperatures ssts were consistent with literature data that indicate ssts 3 c higher than the current ones 2 during mis 9 the lagoon in which unit i formed had a mean water temperature of the coldest month at least 10 12 c higher than that in modern southern adriatic and at least 3 4 c higher than that in some modern north african lagoons therefore our study supports the hypothesis that the mediterranean sea experienced tropical subtropical conditions during mis 9 that were similar to those of mis 11