revisiting tectonic corrections applied to pleistocene sea level highstands tectonic displacement contaminates estimates of peak eustatic sea level and equivalently minimum continental ice volumes determined from the elevation of quaternary interglacial highstand markers for sites at which a stratigraphic or geomorphic marker of peak marine isotope stage mis 5e sea level exists the standard approach for estimating local tectonic uplift or subsidence rates takes the difference between the elevation of the local highstand marker and a reference mis 5e eustatic value commonly chosen as 6 m and divides by the age of the marker the resulting rate is then applied to correct the elevation of all other local observed sea level markers for tectonic displacement including peak highstands of different ages e g mis 5a mis 5c and mis 11 under the assumption that the tectonic rate remained constant over those periods this approach introduces two potentially significant errors first the peak eustatic value adopted for mis 5e in most previous studies i e 6 m is likely incorrect second local peak sea level during mis 5e is characterized by significant departures from eustasy due to glacial isostatic adjustment in response to both successive glacial interglacial cycles and excess polar ice sheet melt relative to present day values we use numerical models of glacial isostatic adjustment that incorporate both of these effects to quantify the plausible range of the combined error and show that even at sites far from melting ice sheets local peak sea level during mis 5e may depart from eustasy by 2 4 m or more we also demonstrate that the associated error in the estimated tectonic rates can significantly alter previous estimates of peak eustatic sea level during quaternary highstands notably those associated with earlier interglacials e g mis 11

u th ages obtained by mass spectrometry in corals from barbados sea level during the past 130 000 years the study of the sea level record during the last glacial cycle has primarily proceeded indirectly by means of oxygen isotope measurements on foraminifera from deep sea sediments1 2 the direct approach of dating sea level indicators stagnated during the past decade mainly because the samples required to complete our knowledge of the past glaciations are below the present day sea level3 7 using the 14c ages of acropora palmata samples collected by drilling offshore the island of barbados fairbanks8 presented the first detailed chronology for the last deglaciation this radiocarbon chronology is limited to the past 30 kyr because of the short half life of 14c 5 730 yr we must therefore rely on other dating methods to obtain information for the whole last glacial cycle during the past four years 230th 234u dating of corals by thermal ionization mass spectrometry has been shown to be significantly more precise and accurate than the classical counting method9 14 we have used this technique to measure u th ages in coral samples from the barbados collection and from subaerially exposed outcrops see also ref 15 here we present results bearing on the sea level record for the past 130 000 years we conclude that the last deglaciation started 3 000 years earlier than previously thought and confirm that there were two surges in melt water8 at about 11 kyr and 14 kyr bp before present

downwearing rates of vertical limestone surfaces in the intertidal zone gulf of trieste italy abstract in 2007 we installed seven micro erosion meter stations on a vertical limestone slab located in the intertidal zone in the gulf of trieste italy in order to observe rock surface changes at elevations ranging between 0 75 m and 0 75 m m s l furlani et al 2010 in this paper we present the micro erosion metre mem data for most months between february 2008 and may 2013 and the traversing micro erosion metre tmem data collected twice a year since 2007 the mem and tmem data were consistent and indicated that the mean lowering rate ranged between 0 007 mm yr and 0 205 mm yr and 0 001 mm yr and 0 260 mm yr according to the elevation of the stations maximum downwearing rates were observed in the mid lower intertidal zone and decreased upward and downward the natural trend of erosion started in 2010 after 2 years of exposure when the slab formerly smoothed and not colonized by marine organisms started to be acclimated to the local environment after 2010 the erosion rate increased to a maximum of 0 31 mm yr this value can be more representative for long term studies and is similar to the downwearing rates locally collected on natural limestone surfaces this dataset represents the first collection of downwearing rates mainly measured using mems but also tmems on vertical limestone surfaces in an intertidal zone and provides interesting new information for addressing the debate on notch genesis and development the shape of a tidal notch has been found to be consistent with the distribution of erosion rates along the slab even if the present day notch was not surveyed in the gulf of trieste due to the local tectonic subsidence

sea level change along the italian coast during the holocene and projections for the future published and new sea level data are used to provide projections of sea level change in italy for the year 2100 by adding new isostatic and tectonic component to the ipcc and rahmstorf projections comparison of the observations from more than 130 sites with different geomorphological and archaeological sea level markers with the predicted sea level curves provides estimates of the vertical tectonic contribution to the relative sea level change the results are based on the most recent anu model for the ice sheets of both hemispheres including an alpine deglaciation model on the basis of the eustatic tectonic and isostatic components to the sea level change projections are provided for marine inundation scenarios for the italian coastal plains for the year 2100 that today are at elevations close to current sea level

middle pleistocene to holocene coastal evolution of nw sardinia mediterranean sea italy abstract the middle pleistocene holocene sardinian stratigraphy has been revised to identify the roles played by sea and climate changes in controlling sedimentation the succession dated through optically stimulated luminescence quartz k feldspar and 14 c the most recent was grouped into eight major stratigraphic units mainly represented by coastal dunes shallow marine and alluvial systems these units range in age from mis 8 300 ka to mis1 6 ka little information is available for the period between mis 8 and 6 the available data however allow some comments on climate changes over the last 125 ka the last interglacial mis 5 is subdivided into five substages e a mis5e eemian is considered the climate optimum of this interglacial sea level was 4 6 m higher than today and climate conditions were warmer and more humid mis 5c is the second high stand peak sea level was about 1 5 m above the modern level and paleoclimatic and paleogeographic conditions were similar to the present during mis 4 at the beginning of the glacial phase a climatic deterioration occurred temperatures dropped by 6c relative to mis 5e in about 5 ka and sea level fell about 60 m this led to a progressive disruption of inland vegetation cover and to repeated valley slope denudation the sea level fall created the accommodation space for fan development in sheltered and cliffed areas where debris flows developed and filled almost completely the terminal parts of the narrow coastal valleys coves in wider areas however coastal dune fields developed contemporaneous presence of alluvial fan and dune systems is associated with the local morphology that could mitigate or amplify moist conditions within a generally arid environment during mis 3 several climate fluctuations occurred wet arid d o h events however the shallow sardinian shelf was continuously sufficiently exposed to become the source area of bioclastic sands these sands were blown inland and formed extensive dunefield systems dunes dominated the west coasts of sardinia under cold and relatively dry conditions in some areas these dunefield systems were eventually almost completely dismantled and reworked into water flow dominated alluvial fans by catastrophic rainfall events thus the local climate quickly switched from arid to humid conditions no record of the last glacial maximum deposits mis 2 was observed along the nw sardinian coast during the holocene transgression mis1 coastal dune systems developed and progressively migrated inland and temperature rose to reach the present day condition

elevation of the last interglacial highstand in sicily italy a benchmark of coastal tectonics well preserved mis 5 5 terraces in sicily are identified primarily by the index fossil strombus bubonius and dated by amino acid racemization aar electron spin resonance esr uranium thorium u th and thermo luminescence tl methods this review of published data and new results for the island of sicily and neighbouring small islands of egadi ustica and lampedusa identifies areas of rapid uplift in the east up to 175 m elevation above sea level slower uplift in the north 29 m and relative stability in the northwest 2 18 m in contrast about 250 km of the southern coastline of sicily does not appear to contain mis 5 5 outcrops in eastern sicily correlation of mis 5 5 highstands is based on strombus bubonius discovered at 86 m and correlated with the inner margin terrace at 110 m in the taormina area a fossiliferous marine conglomerate on a terrace with an inner margin at 115 m occurs in an area with undated terrace morphology and elevation data based on esr methodology applied to fossils sampled at 105 m in taormina we attribute this terrace to mis 5 probably 5 5 this age allows us to constrain the date of one point along a very long coastline that is otherwise undated a newly discovered fossil beach between 7 and 9 m at cefalu north central sicily attributed to mis 5 1 5 3 using aar analysis permits correlation of mis 5 5 to a 29 m high tidal notch geomorphologically related to a terrace at the same elevation cefalu lies in an important position between the uplifted coastline of northeastern sicily and the more stable coastline of western sicily this compilation of mis 5 5 data for all of sicily reflects the active tectonics of eastern sicily in contrast to the rest of the island

u series measurements in tyrrhenian deposits from mallorca further evidence for two last interglacial high sea levels in the balearic islands the campo de tiro type section for the tyrrhenian ecostratigraphic beds of the balearic islands shows four indurated littoral conglomerates and beach rocks unconformably superimposed the lower two units 1 and 2 are separated by a thin layer of reddish continental silts both contain a typical eutyrrhenian fauna whereas a neotyrrhenian fauna characterizes the overlying units 3 and 4 thu measurements by thermal ionisation mass spectrometry on mollusk shells from these deposits yielded ages of 135 ka unit 1 117 ka units 2 and 3 and a scatter of ages around 100 ka unit 4 the stratigraphic relationships and thu data indicate i that uranium was uptaken by mollusks shells but arca sp each time during a relatively short early diagenetic interval before cementation ensured a fair closure of the radioactive system ii two high sea stands characterized the last interglacial isotopic substage 5e of the balearic islands area iii the duration of this episode was 17 ka and iv the change in faunal assemblages and disconformity observed between units 2 and 3 are due to fluctuations in sea level and surface water conditions which occurred during the second high sea level episode of the last interglacial

chronostratigraphic confirmation of mis 5 age of a baymouth bar at is arenas cagliari italy in 2005 the national geological survey of italy released the new sheet 557 cagliari 1 50 000 scale a coastal barrier marine formation at is arenas cagliari sardinia italy containing strombus bubonius was reassigned a holocene age in contradiction with extensive literature published over the past century indicating an mis 5 5 age in 2007 spurred by this controversy a short note was published in il quaternario demonstrating the stratigraphic difficulties in attributing the age of this formation to the holocene later another paper signed by numerous italian geologists was published in il quaternario criticizing the holocene attribution the tectonic consequences of assigning a holocene age to these deposits are of great significance as their elevation could only be explained by strong uplift over the past few thousand years such a tectonic setting would imply a radical change in the recent geodynamic history of sardinia which is considered to be among the most stable areas of the mediterranean basin this paper provides further geochronological data for a mis 5 age for the deposits at is arenas electron spin resonance esr analyses were performed on 4 fossil shells sampled along the fossil baymouth bar the results established an mis 5 age the amino acid racemization aar and u series data that first determined a correlation with the last interglacial tyrrhenian age of this ancient shoreline is reviewed with additional documentation provided by the fossil marker s bubonius

long term shore platform surface lowering rates revisiting gill and lang after 32 years abstract in 1978 e d gill and j g lang installed 53 micro erosion meter mem sites on shore platforms along the otway coast in south eastern australia surface lowering rates were originally determined from 2 yr of measurements 1979 and 1980 and showed that the mean annual rate of lowering from all sites was 0 37 mm yr 1 we re measured these mem sites 32 yr after the first set of readings were taken in february 1979 we relocated 49 of the original 53 bolt sites and were able to measure 45 of them from the sites we measured the mean annual rate of shore platform lowering was 0 31 mm yr 1 rates of surface lowering on shore platforms are commonly reported from studies of only two or three years and only one other record exceeds 30 yr kaikoura peninsula nz 1 09 mm yr 1 in that case fewer than half of the original bolt sites were functioning because erosion had removed bolts along the otway coast rates of erosion are much slower hence the greater number of still readable sites after 32 yr compared to other micro erosion meter studies the rates reported here are at the lower end of the range of values from around the world but nevertheless consistent with rates from the otway coast and others in similar lithology we found no statistical difference between erosion rates calculated over 2 yr 1979 to 1980 and 32 1979 to 2011 years supporting the view that shore platform lowering rates measured over 2 yr are representative of decadal scales

towards an improved understanding of erosion rates and tidal notch development on limestone coasts in the tropics 10 years of micro erosion meter measurements phang nga bay thailand knowledge and understanding of shore platform erosion and tidal notch development in the tropics and subtropics relies mainly on short term studies conducted on recently deposited carbonate rocks predominantly holocene and quaternary reef limestones and aeolianites this paper presents erosion rates measured over a 10 year period on notches and platforms developed on the permian ratburi limestone at phang nga bay thailand in so doing it contributes to informing a particular knowledge gap in our understanding of the erosion dynamics of shore platform and tidal notch development in the tropics and subtropics notch erosion rates on relatively hard ancient limestones measured directly on the rock surface using a micro erosion meter mem over time periods of a decade or more the average intertidal erosion rate of 0 231 mm yr is lower than erosion rates measured over 2 3 years on recent weaker carbonate rocks average erosion rates at phang nga vary according to location and site and are in rank order from highest to lowest mid platform 0 324 mm yr notch floor 0 289 mm yr rear notch wall 0 228 mm yr lower platform 0 140 mm yr notch roof 0 107 mm yr and supratidal 0 095 mm yr the micro relief of the eroding rock surfaces in each of these positions exhibits marked differences that are seemingly associated with differences in dominant physical and bio erosion processes the results begin to help inform knowledge of longer term shore platform erosion dynamics models of marine notch development and have implications for the use of marine notches as indicators of changes in sea level and the duration of past sea levels copyright 2014 john wiley sons ltd

assessment of pyrite composition by la icp ms techniques from massive sulfide deposits of the bathurst mining camp canada from textural and chemical evolution to its application as a vectoring tool for the exploration of vms deposits abstract pyrite is ubiquitous throughout the massive sulfide deposits of the bathurst mining camp canada pyrite locally preserves primary pseudo primary textures as well as secondary textures that formed in response to the hydrothermal metamorphic and deformation processes to which the host sequence was exposed in the bathurst mining camp most forms of pyrite are arsenian up to 3 13 wt as with considerable enrichment in tl sb sn bi ag se and to a lesser extent cd ga te hg ge in and au la icp ms analyses of primary pyrite show significant enrichment in fluid mobile elements in particular tl sb as and hg as well as bi pb and sn in contrast secondary pyrite syn to post deformation varieties is not enriched in these elements superimposed metamorphism typically causes loss of fluid mobile elements to different degrees except for se pyrite chemical variations have the potential to monitor ore petrogenesis at inter and intra deposit scales pyrite from the cu zone is enriched in se relative to pyrite from zn pb zone in which tl is elevated throughout the host sequence fluid mobile element concentrations of pyrite vary by several orders magnitude with the highest fluid mobile element abundances in footwall rocks immediately proximal to the deposit moreover elevated fluid mobile element concentrations of pyrite are recognized in footwall felsic volcanic and sedimentary rocks as much as several hundred metres away from the deposit hanging wall zones contain pyrite with fluid mobile element contents comparable to pyrite from sulfide horizon the fluid mobile element concentrations of pyrite are higher in exhalative sedimentary rocks than pyrite from the sulfide mineralization itself the spatial variation in fluid mobile element concentrations in pyrite as identified using la icp ms can be used to identify otherwise cryptic deposit related haloes ultimately this technique when combined with traditional exploration tools can be used to vector toward vms mineralization in the bathurst mining camp and possibly a useful indicator in a prospect scale base metal exploration

vertical gps ground motion rates in the euro mediterranean region new evidence of velocity gradients at different spatial scales along the nubia eurasia plate boundary we use 2 5 to 14 years long position time series from 800 continuous global positioning system gps stations to study vertical deformation rates in the euro mediterranean region we estimate and remove common mode errors in position time series using a principal component analysis obtaining a significant gain in the signal to noise ratio of the displacements data following the results of a maximum likelihood estimation analysis which gives a mean spectral index 0 7 we adopt a power law white noise stochastic model in estimating the final vertical rates and find 95 of the velocities within 2 mm yr with uncertainties from filtered time series 40 smaller than from the unfiltered ones we highlight the presence of statistically significant velocity gradients where the stations density is higher we find undulations of the vertical velocity field at different spatial scales both in tectonically active regions like eastern alps apennines and eastern mediterranean and in regions characterized by a low or negligible tectonic activity like central iberia and western alps a correlation between smooth vertical velocities and topographic features is apparent in many sectors of the study area glacial isostatic adjustment and weathering processes do not completely explain the measured rates and a combination of active tectonics and deep seated geodynamic processes must be invoked excluding areas where localized processes are likely or where subduction processes may be active mantle dynamics is the most likely process but regional mantle modeling is required for a better understanding

origin of modern quartzarenite beach sands in a temperate climate florida and alabama usa abstract quartzarenite coastal sands extending from eastern louisiana eastward to apalachee bay florida are anomalous their position 7 north of the tropic of cancer contrasts with most other known modern quartzarenites most of which are in a tropical setting to determine the origin of these quartzarenite beach sands we compared the mineralogy of samples taken from alabama and florida beaches rivers that supply sand to the coast and well cuttings representative of sandstone bedrock exposed in the alabama coastal plain to help assess the abundance of recycled quartz and accepting the conventional wisdom that rounded sand size quartz grains are recycled we quantified the roundness of quartz grains in thin sections of river beach and well samples we also determined the abundance of recycled grains with authigenic quartz using cathodoluminescence river sands on precambrian and paleozoic bedrock in the study area have subarkose and sublitharenite compositions however as far as 200 km inland from the coast river sands have attained quartzarenite composition and all rivers are presently delivering sand with at least 97 quartz to the coast rivers develop quartzarenite sand composition where they traverse poorly consolidated tertiary sandstones all of which we sampled are composed of 95 quartz published experimental work indicates that abrasional rounding of sand size quartz by rivers is insignificant and rounding in beaches is extremely slow hence the abundance of quartz grains with some degree of rounding 96 for beaches 75 for rivers further attests to the abundance of recycled quartz

sardinia coastal uplift and volcanism the low variability of mis 5 5 sea level m i s marine isotopic stage with respect to the present day sea level allows the sardinian coast to be used as an eustatic reference for the entire mediterranean region this level is generally at 7 2 m above current sea level along the sardinian coast one sector along the orosei gulf eastern sardinia includes a characteristic and well conserved tidal notch that changes in elevation from 7 6 to 11 5 m over only 30 km tilting upwards towards the north generally height deviations of such a tidal notch would be due to tectonic or volcanic activity the sardinia coast however is considered to have too little tectonic activity and also too small post glacial rebound in order to explain the anomaly the remaining possibility is neogene quaternary continental and or submarine volcanic activity which we investigate as a possible cause for the observed anomalies in this paper our goal is to explain the anomaly by modelling recent volcanic loading or updoming related to magmatic intrusion emplacement we review the literature on the recent volcanic deposits both on shore and off shore and investigate to what extent volcanic loads can influence the coastline from a theoretical standpoint using the isostatic flexure model and a range of loads we find that the observed notch height anomaly cannot be explained by volcanic loading but must be produced by an upward welling due to the emplacement of volcanic material as produced for instance by a laccolith or batholith the upward movement could be related to the submarine volcano only recently detected or to a source located on the eastern sardinia coast near orosei

gps velocity and strain fields in sicily and southern calabria italy updated geodetic constraints on tectonic block interaction in the central mediterranean 1 we present an improved rendition of the geodetic velocity and strain fields in sicily and southern calabria obtained through the analysis of 18 years of gps observations from continuous and survey station networks the dense spatial coverage of geodetic data provides precise quantitative estimates of previously established first order active kinematic features including i a narrow east west elongated belt of contraction 1 1 5 mm yr extending offshore northern sicily from ustica to stromboli across the aeolian islands ii a narrow east west trending contractional belt located along the northern rim of the hyblean plateau in southern sicily with shortening at up to 4 4 mm yr iii right motion 3 6 mm yr on the aeolian tindari letojanni fault atlf system a main shear zone extending from the aeolian islands to the ionian coast of sicily with significant transpression and transtension partitioned between discrete sectors of the fault iv transtension 1 mm yr across the sicily channel between sicily and north africa we use geodetic observations coupled to geological constraints to better elucidate the interplay of crustal blocks revealed in the investigated area in particular we focus on the atlf which forms the primary boundary between the sicilian and calabrian blocks the atlf juxtaposes north south contraction between sicily and the tyrrhenian block with northwest southeast extension in northeastern sicily and calabria contraction between sicily and tyrrhenian blocks probably arises from the main europe nubia convergence although sicily has a component of lateral motion away from nubia we found that convergence is not restricted to the northern offshore as commonly believed but is widely accommodated between the frontal belt and the northern rim of the hyblean foreland in southern sicily geodetic data also indicate that active right shear on the atlf occurs to the southeast of the mapped fault array in northern sicily suggesting the fault cuts through till the ionian coast of the island the small geodetic divergence between the hyblean and apulian blocks rimming on both sides the calabria block and subjacent ionian slab coupled with marine geophysical evidences in the ionian sea lends credit to the proposed deep root of the atlf and to a fragmentation of the ionian domain

space geodesy constrains ice age terminal deglaciation the global ice 6g_c vm5a model a new model of the last deglaciation event of the late quaternary ice age is here described and denoted as ice 6g c vm5a it differs from previously published models in this sequence in that it has been explicitly refined by applying all of the available global positioning system gps measurements of vertical motion of the crust that may be brought to bear to constrain the thickness of local ice cover as well as the timing of its removal additional space geodetic constraints have also been applied to specify the reference frame within which the gps data are described the focus of the paper is upon the three main regions of last glacial maximum ice cover namely north america northwestern europe eurasia and antarctica although greenland and the british isles will also be included if peripherally in the discussion in each of the three major regions the model predictions of the time rate of change of the gravitational field are also compared to that being measured by the gravity recovery and climate experiment satellites as an independent means of verifying the improvement of the model achieved by applying the gps constraints several aspects of the global characteristics of this new model are also discussed including the nature of relative sea level history predictions at far field locations in particular the caribbean island of barbados from which especially high quality records of postglacial sea level change are available but which records were not employed in the development of the model although ice 6g c vm5a is a significant improvement insofar as the most recently available gps observations are concerned comparison of model predictions with such far field relative sea level histories enables us to identify a series of additional improvements that should follow from a further stage of model iteration

temporal evolution of the roccamonfina volcanic complex pleistocene central italy abstract the roccamonfina volcanic complex rvc in southern italy is an early to middle pleistocene stratovolcano sharing temporal and morphological characteristics with the somma vesuvius and the alban hills both being associated with high volcanic hazard for the cities of naples and rome respectively the rvc is important for the understanding of volcanic evolution in the roman and campanian volcanic provinces we report a comprehensive study of its evolution based on morphological geochemical and k ar geochronological data the rvc was active from c a 550 ka to 150 ka its evolution is divided into five stages defining a volcanic pulse recurrence time of c a 90 100 kyr the two initial stages consisted in the construction of two successive stratovolcanoes of the tephrite phonolite namely high k series the first stage was terminated by a major plinian eruption emplacing the trachytic rio rava pumices at 439 9 ka at the end of the second stage the last high k series stratovolcano was destroyed by a large sector collapse and the emplacement of the brown leucitic tuff blt at 353 5 ka the central caldera of the rvc is the result of the overlapping of the rio rava and of the blt explosions the plinian eruption of the blt is related to the emptying of a stratified deep seated hks magma chamber during the upwelling of k series ks magma marking a major geochemical transition and plumbing system re organization the following stage was responsible for the emplacement of the lower white trachytic tuff at 331 2 ka and of basaltic trachytic effusive products erupted through the main vent the subsequent activity was mainly restricted to the emplacement of basaltic shoshonitic parasitic cones and lava flows and of minor subplinian deposits of the upper white trachytic tuff between 275 and 230 ka the northern crater is most probably a maar that formed by the phreatomagmatic explosion of the yellow trachytic tuff at 230 ka the latest stage of activity featured the edification of the central shoshonitic domes at c a 150 ka

precise chronology of the last interglacial period 234u 230th data from fossil coral reefs in the bahamas a detailed study of 238 u 234 u 230 th ages was made for different coral species from two bahamian reefs to determine the time scale of the sea level high during the last interglacial period using recently developed mass spectrometric techniques for the measurement of u and th isotopes thirty seven coral samples were analyzed in replicate typical errors at 125 ky are 1 5 ky 2 and 3 ky time intervals appear to be well resolved this high precision permits detailed chronologic study with time resolution adequate to define stages of the reef s history these data demonstrate that the time between transgression and regression of the ocean in the last interglacial was about 12 ky after which sea level fell rapidly at more than 2 m ky the high sea level stand began possibly by 132 ky and certainly by 129 ky ago when sea level reached 6 m above present mean low sea level high sea level was sustained until 120 ky and then fell rapidly this time period covers the milankovitch insolation peak at 65 n but is not sharply defined and the sea level high lasted from about 4 ky before the insolation peak to 8 ky after it we find no evidence for a double peak of sea level rise in the last interglacial episode that is high stands at both 125 and 142 ky there appears to be some discrepancy between this precise chronology for a coral reef on a tectonically stable platform and the chronology assigned to deep sea sediments the present results show that the duration of the last interglacial led to a 12 ky period of high sea level stand which is much longer than the insolation peak the study area consists of two sizeable bank barrier coral reefs of sangamon age that crop out along the coast northwest of cockburn town on san salvador island and at devil s point on great inagua island the initial stage of reef development is not revealed at either site but the main parts of both reefs are well preserved at cockburn town the beginning of the reef was marked by colonization of acropora palmata on hardground areas and possibly other corals at 132 ky ago patch reefs at the southeastern flank of the developing reef were growing by 129 to 126 ky ago by 126 to 123 ky ago the crest of the reef was formed by the frame building coral a palmata and associated patch reefs flourished along its flanks a palmata coral heads grew upward to a mean low sea level 6 m above the present one the reef began to decline as sea level dropped at about 123 to 120 ky ago near two measured profiles at devil s point the top of a rubblestone dominated by a cervicornis and patch reef corals preserved in growth position have been beveled off and represent an ancient wave cut surface 230 th ages on corals below and above this surface indicate that it was cut at about 125 1 ky ago

a revised morpho and chronostratigraphy of the late and middle pleistocene coral reef terraces on southern barbados west indies the barbados coral reef terraces are one of the few type localities worldwide that provide insights into interglacial sea level change during the late and middle pleistocene several sea level estimates have been established since the late 1960s and each has contributed to the barbados model of sea level change this paper presents new morpho and chonostratigraphic data from the barbados coral reef terraces developed over the last 12 years the work is based on significant advances in electron spin resonance esr dating of fossil coral air photo interpretation and a greatly improved geomorphic map of preserved fossil beach formations and reef terraces above present sea level the need for a revision of past published morpho and chronostratigraphies is best demonstrated on the southern part of the island the morpho and chronostratigraphic sequence in this region is both more complex and diverse than has been assumed so far the revised morphostratigraphy presented here includes a differentiation of coral reef terraces wave cut platforms and other erosive features such as notches and cliffs our study of these geomorphic features combined with new numeric dating results esr u th enable a revised estimate of the spatial and temporal variation in tectonic uplift rate within south barbados these new rates are an essential requirement for more precise glacio eustatic sea level reconstructions during the late and middle pleistocene from this region

geochemistry of sulfide minerals from skarn cu au deposits in the fenghuangshan ore field tongling eastern china insights into ore forming process abstract in situ elemental compositions of sulfide minerals have been widely applied to trace ore forming processes of magmatic hydrothermal ore systems yet the application of elemental compositions of the sulfide minerals in skarn ore deposits is still restricted by the lack of understanding of their behaviors during the skarn formation processes in this study in situ la icp ms and epma elemental compositions of medium to coarse grained euhedral pyrite and xenomorphic granular chalcopyrite are investigated for the fenghuangshan and baoshantao skarn cu au deposits in the tongling region eastern china the results show that the studied pyrite samples have relatively consistent trace element composition characteristics while the chalcopyrite studied displays high zn ag and pb contents and relatively high bi content au ag cu pb bi sb and tl are mainly of lattice bound appearance in the pyrite structure the au ag sb pb and bi are mainly incorporated into the chalcopyrite structure as coupled substitutions low au mainly 1 and se tl mainly 10 ratios of the pyrite studied and high sn 10 ppm and low tl

morphometry and elevation of the last interglacial tidal notches in tectonically stable coasts of the mediterranean sea abstract we report detailed morphometric observations on several mis 5 5 and a few older mis 11 21 25 fossil tidal notches shaped along carbonate coasts at 80 sites in the central mediterranean sea and at an additional six sites in the eastern and western mediterranean at each site we performed precise measurements of the fossil tidal notch ftn width and depth and of the elevation of its base relative to the base of the present tidal notch ptn the age of the fossil notches is obtained by correlation with biologic material associated with the notches at or very close to the site this material was previously dated either through radiometric analysis or by its fossiliferous content the width i e the difference in elevation between base and top of the notches ranges from 1 20 to 0 38 m with a mean of 0 74 m although the ftn is always a few centimetres wider than the ptn probably because of the lack of the biological reef coupled with a small erosional enlargement in the ftn the broadly comparable width suggests that tide amplitude has not changed since mis 5 5 times this result can be extended to the mis 11 features because of a comparable notch width but not to the mis 21 and 25 epochs although observational control of these older notches is limited we regard this result as suggesting that changes in tide amplitude broadly occurred at the early middle pleistocene transition the investigated mis 5 5 notches are located in tectonically stable coasts compared to other sectors of the central mediterranean sea where they are uplifted or subsided to 100 m and over in these stable areas the elevation of the base of the mis 5 5 notch ranges from 2 09 to 12 48 m with a mean of 5 7 m such variability although limited indicates that small land movements deriving from slow crustal processes may have occurred in stable areas we defined a number of sectors characterized by different geologic histories where a careful evaluation of local vertical land motion allowed the selection of the best representative elevation of the mis 5 5 peak highstand for each sector this elevation has been compared against glacial isostatic adjustment gia predictions drawn from a suite of ice sheet models ice g5 ice g6 and anice selen that are used in combination with the same solid earth model and mantle viscosity parameters results indicate that the gia signal is not the main cause of the observed highstand variability and that other mechanisms are needed the gia simulations show that even within the mediterranean basin the maximum highstand is reached at different times according to the geographical location our work shows that besides gia even in areas considered tectonically stable additional vertical tectonic movements may occur with a magnitude that is significantly larger than the gia

holocene coastal notches in the mediterranean region indicators of palaeoseismic clustering abstract marine tidal notches are developed by bioerosion in the intertidal zones of rocky coasts but a combination of sea level change and crustal movements can result in them being raised above or submerged below the water line for that reason the present day elevation of these former shorelines relative to the mean sea level has long been used to quantify relative coastal uplift and subsidence in tectonically active areas assuming that the sea level eustatic change component is known along the microtidal mediterranean littoral it is generally assumed that notches develop during relative stillstands of sea level when tectonic and eustatic trends are in unison and that discrete notch levels record abrupt shoreline changes caused by local seismic displacements recently however a climatic model for notch formation has been proposed in which stable periods of holocene climate favour enhanced erosion in this competing model the rate of sea level rise is lower than the tectonic uplift rate and individual notches are not specific seismic indicators because marine notches are widely used as geomorphic markers of tectonic and in some cases palaeoseismic movements a reappraisal of the geological significance of these strandlines is warranted in this paper we explore the two conflicting notch models using a database of eastern mediterranean palaeoshorelines although we conclude that the spatial and temporal distribution of the notches supports a dominantly tectonic control on notch genesis as a result of earthquake clustering we highlight how the diachronous timing of notch development tempers their value as tectonic markers

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

coastal notches their morphology formation and function deep coastal notches develop through undercutting of steep coastal slopes consisting of rocks that are strong enough to support the weight of the overburden notches are found from the tropics to the poles and in a wide range of rock types virtually tideless to megatidal seas and high to low wave energy environments the emphasis in the literature has been on notches in calcareous rocks in warm microtidal seas and with the general assumption that they have been produced by bioerosion or chemical dissolution few scientifically rigorous attempts have been made to determine the processes responsible for notch formation in different environments and rock types however or to determine whether different processes produce distinct notch morphologies within the same tidal and wave environments the use of notches as palaeo sea level markers and to determine rates of tectonic uplift has been particularly important in the mediterranean notches are more difficult to employ for this purpose in the middle latitudes where higher waves and tides amplify the range of elevations over which the erosional mechanisms are effective as well as increasing the exposure and effect of rocks of variable resistance to erosion to maximize the utility of notches as sea level markers and to better understand and model their development in a wide range of environments we need to understand and be able to quantify the relationship between notch shape and size and the elevational efficacy of the various erosional processes

new data on the pleistocene of mallorca abstract stratigraphic geomorphologic and isoleucine epimerization studies at 15 sites in mallorca define four aminozones a c e and f g of increasing age that are related to transgressive regressive marine cycles from the holocene to the mid pleistocene calibration of aminozone e glycymeris aile ile mean from all sites 0 41 0 03 n 38 is provided by a 129 7 ka u series coral age on cladocora caespitosa from son grauet of the younger aminozones a relates to the holocene transgression and aminozone c to a mid to late isotopic stage 5 event 90 15 ka revealed only by supralittoral eolianites assigning an age to the older poorly resolved aminozones f and g called f g in this case is uncertain without supporting radiometric data but an age of 180 ka can be assigned to these aminozone s f g based on a kinetic model and other examples in the mediterranean several deposits previously dated u series molluscs between 75 and 300 ka appear to belong to the last interglacial complex stage 5 and aminozone e a proposed revision of the positive sea level history of mallorca shows multiple minor oscillations during the major last interglacial cycle stage 5 and two mid pleistocene sea levels one lower than present and the other at about 14 m a s l

bermuda sea level during the last interglacial bermuda is a stable mid oceanic carbonate platform for which a particularly complete record of sea level fluctuation during the period 135 70 kyr has been reconstructed from 230th 234u dating of corals and speleothems amino acid racemization dating of molluscs and a reinterpretation of geological field relations during the past 5 yr bermuda has been the focus of an extensive geochronological programme which has included a detailed re examination of the geology to be reported elsewhere1 3 here we focus only on the latest interglacial sequence we use the stratigraphie nomenclature of land et al 4 but will present new age data and interpretations of geological relationships this information as it relates to the last interglacial period is given in tables 1 and 2 and summarized in fig 1 we show that during the last interglacial period sea level was only above its present level for a few thousand years at about 125 kyr when it stood at 4 to 6m at 105 and 85 kyr sea level rose to between 15 and 20 m as constrained by ages for submerged speleothems and eolianites at 95 kyr sea level in bermuda was at least 15 m below present level

active fragmentation of adria the north african promontory central mediterranean orogen global positioning system gps velocities indicate that adria no longer behaves as a rigid tectonic indenter into southern europe and is divided into northwestern and southeastern velocity domains differential motions are recognized in a velocity field determined from the peri tyrrhenian geodetic array ptga and international gps service igs sites in the circum tyrrhenian region of the central mediterranean and published gps velocities from the eastern adriatic coast in a fixed eurasian reference frame ptga and igs site velocities in sicily and southern italy are as much as 10 mm yr in a northward direction similar to gps velocities along the eastern coast of the adriatic sea in contrast velocities in northern italy are small or statistically insignificant and similar to velocities in sardinia and corsica outboard of western adria the tectonic boundary dividing adria is seismically active and passes around the southern and eastern margins of the tyrrhenian basin crosses central italy extends into the adriatic sea and follows the western margin of the dinaride tectonic belt north to the gulf of venice the eastern margin of adria is approximately located and follows the axis of the central dinaric alps southeast to the hellenic arc southeastern adria has a velocity related to northward motion of africa whereas northwestern adria has negligible differential motion in the eurasian frame and now is part of the alpine collage of southern europe

rock coasts with particular emphasis on shore platforms rock coasts are one of the most common elements of the world s littoral zone and they are often important sources of sediment for estuaries and beaches economic development growing populations and the potential effects of rising sea level provide a practical need to understand the dynamics of these coasts although there have been significant advances in our understanding of rocky coastal systems further progress has been hindered by a lack of researchers and by the often imperceptible changes that generally occur within human time scales this paper reviews rock coast processes and landforms in a variety of morphogenic environments one of our most fundamental challenges is to determine the degree to which rock coasts are contemporary rather than inherited features from the quaternary when changes in sea level and climate were responsible for marked variations in the nature intensity and elevational distribution of the marine and subaerial processes that sculpture rock coasts

ice volume and sea level during the last interglacial during the last interglacial period 125 000 years ago sea level was at least several meters higher than at present with substantial variability observed for peak sea level at geographically diverse sites speculation that the west antarctic ice sheet collapsed during the last interglacial period has drawn particular interest to understanding climate and ice sheet dynamics during this time interval we provide an internally consistent database of coral u th ages to assess last interglacial sea level observations in the context of isostatic modeling and stratigraphic evidence these data indicate that global eustatic sea level peaked 5 5 to 9 meters above present sea level requiring smaller ice sheets in both greenland and antarctica relative to today and indicating strong sea level sensitivity to small changes in radiative forcing

evidence of mis 5 sea level highstands in gebel mousa coast strait of gibraltar north of africa abstract the last interglacial is considered the most suitable episode from which to infer patterns of rapid sea level change since its climatic conditions were similar to those of the present interglacial however specifying the true position of its sea level with high accuracy is very troublesome in the absence of sedimentological erosional or even palaeontological markers this study investigates the morphosedimentary evidence beach deposits cliff notch and shore platform of two highstands registered and dated during mis 5 stage by u series dating in the north of morocco strait of gibraltar bioerosive notches and mixed siliciclastic and carbonate deposits high energy beaches with algal bioherms were formed in coastal environments during mis 5a a sea level height of 10 m asl can be inferred for this substage the record of mis 5e substage is less defined in the geomorphological record consisting of backshore foreshore deposits located at 13 to 15 m asl a tectonic uplift rate of 0 1 mm yr has been estimated for the last 130 kyr these data are consistent with models of coastal uplifting calculated for the strait of gibraltar

geological and geochemical constraints on the genesis of the xiangquan tl only deposit eastern china abstract the xiangquan tl deposit located in the northern part of the middle lower yangtze valley metallogenic belt eastern china is the only known tl only deposit it is hosted in micritic limestone marl and mudstone of the lower ordovician lunshan formation the orebodies are controlled by the xiao xiaolongwang dalongwang anticline and two reverse faults and are generally stratabound and lenticular tl is only ore metal contained in disseminated massive brecciated and banded ores the ore is composed of tl bearing pyrite and gangue minerals quartz fluorite barite and carbonate alteration minerals include fluorite barite fine grained quartz and carbonate tl occurs isomorphously replacing iron in the lattice of pyrite and less commonly as tiny independent tl bearing minerals which may be lafossaite tlass 2 or lorandite tlcl appearing as 0 1 1 m sized cubic crystals xiangquan is a submarine sedimentary deposit and demonstrates that tl as a normally dispersed element can form not only part of poly metallic deposits but also as independent tl deposits

a new technique for evaluating short term rates of coastal bioerosion and bioprotection a multi scale and multi method approach has been developed to evaluate the nature and effects of short term biological colonisation this method has been used at falasarna on the western coast of crete to investigate bioprotection and bioerosion on a microtidal rocky coast eighteen blocks of limestone 5 5 2 cm were exposed for 7 months september 1998 to april 1999 at mean sea level at two exposed sites and one sheltered site biological colonization and its impacts were assessed by optical microscopy om scanning electron microscopy sem and multiphoton laser scanning microscopy mplsm exposed sites became colonized more quickly than the sheltered site and once a cover of foliose and filamentous algae had become established bioerosion by cyanobacteria biological etching and chemical weathering were reduced consequently there appears to be an inverse relationship between macroalgal abundance and bioerosion of experimental substrata after 7 months of colonisation thus some level of bioprotection appears to be provided by macro algae under exposed site conditions and would probably become increasingly apparent in longer term research trials

coastal deformation between the versilia and the garigliano plains italy since the last interglacial stage the opening of the north central tyrrhenian sea is the result of the cretaceous paleogene alpine collision which triggered a series of regional uplift subsidence and transcurrent tectonic mechanisms along the coastal tyrrhenian sectors of peninsular italy these tectonic pro cesses in conjunction with the effects of glacio and hydro isostasy during the quaternary produced substantial crustal responses that in some cases reached metres in extent in the study of coastal neotectonics geomorphological markers of the last interglacial maximum corresponding to marine isotope stage 5 5 are generally used to quantify the magnitude of the vertical crustal displacements that have occurred since 125 kyr through altimetrical palaeoenvironmental and chronological reinterpretation of the most significant works published since 1913 combined with an additional set of data reported here a detailed reconstruction of the shoreline displacements evident along 500 km of coast between northern tuscany and southern latium is presented the reconstruction was carried out by quantifying the vertical movement since the last interglacial period and by identifying the tectonic behaviour of different coastal sectors this has been done by carefully choosing the eustatic marker among those available at each study site in order to minimize the margin of error associated with the measurements copyright 2003 john wiley sons ltd

submerged notches in istria and the gulf of trieste results from the geoswim project abstract this paper is aimed at mapping the submerged notch along the northeastern adriatic coast and discussing the relations between the submerged notch the seawater the groundwater and the freshwater discharge along the coasts of the study area using hydrological and observational data collected during a solitary snorkel swimming expedition along 250 km long route along the istrian coasts and thermal and topographical data we discuss the hydrogeological and topographical constraints on the origin and development of the submerged notch in the northeastern adriatic sea the submerged notch was surveyed at depths ranging between 0 6 m m s l and 2 6 m m s l in the northern sector of the gulf of trieste italy and at about 0 5 0 7 m m s l along the limski channel croatia along the savudrija peninsula a slightly carved submerged notch was surveyed at 0 5 0 6 m m s l the modern notch is completely lacking in the study area topographical data highlight that the submerged notch occurs in correspondence of plunging cliffs moreover the submerged notch developed in correspondence of the submarine springs that allow mixing zone dissolution data suggest that the mixing zone dissolution caused by the freshwater from submerged springs or from the largest rivers in the gulf of trieste was a major factor in developing submerged notches these new observations provide basic data for future studies on the development of the submerged notch along the northeastern adriatic coast previously linked almost exclusively to bioerosion

middle late pleistocene polycyclic evolution of a stable coastal area southern apulia italy abstract the otranto leuca coastal tract is marked by the presence of numerous sea caves placed close to present sea level they are located generally at the back of a shore platform covered by a sequence of breccia deposits marine sediments and speleothems at grotta di masseria dell orte marine cemented sands rest on a narrow shore platform at about 6 2 m above mean sea level and are covered by speleothems older than 185 ka at grotta del diavolo which is mostly filled by breccia deposits three beach levels have been detected at about 3 0 3 5 and 5 9 m above msl they are either covered by or overlie speleothems that yield an u th age of 340 78 ka and between 170 3 and 146 5 respectively geomorphological evidence and radiometric ages indicate that the area after a period of uplift has been tectonically stable since the last part of the middle pleistocene so that marine landforms close to the present shoreline underwent a polycyclic evolution the sedimentary fills of sea caves formed during middle late pleistocene glacial stages when arid or semiarid conditions promoted the removal of regolith and the development of thick breccia deposits during marine isotope stages mis 9 3 5 5 and 5 1 cave sediments were partially eroded whereas beach layers and related speleothems developed these are in fact the only marine isotope stages marked by a sea level position which in this mediterranean region was either close to or slightly higher than the present one

thallium isotope variations in an ore bearing continental igneous setting collahuasi formation northern chile abstract thallium is a highly incompatible element and a large fraction of the bulk silicate earth tl budget is therefore expected to reside in the continental crust nonetheless the tl isotope systematics of continental rocks are essentially unexplored at present here we present new tl isotope composition and concentration data for a suite of 36 intrusive and extrusive igneous rocks from the vicinity of porphyry cu deposits in the collahuasi formation of the central andes in northern chile the igneous lithologies of the rocks are variably affected by the hydrothermal alteration that accompanied the formation of the cu deposits the samples display tl concentrations that vary by more than an order of magnitude from 0 1 to 3 2 g g whilst e 205 tl ranges between 5 1 and 0 1 e 205 tl is the deviation of the 205 tl 203 tl isotope ratio of a sample from a standard in parts per 10 4 these variations are primarily thought to be a consequence of hydrothermal alteration processes including metasomatic transport of tl and formation breakdown of tl bearing minerals which are associated with small but significant tl isotope effects the tl abundances show excellent correlations with both k and rb concentrations but no co variation with cu this demonstrates that tl displays only limited chalcophile affinity in the continental crust of the collahuasi formation but behaves as a lithophile element with a distribution that is primarily governed by partitioning of tl into k bearing phases collahuasi samples with propylitic alteration features which are derived from the marginal parts of the hydrothermal systems have on average slightly lighter tl isotope compositions than rocks from the more central sericitic and argillic alteration zones this small but statistically significant difference most likely reflects preferential retention of isotopically heavy tl in alteration phases such as white micas and clays which formed during sericitic and argillic alteration

modelling tidal notch formation by wetting and drying and salt weathering abstract the formation and morphology of marine notches formed by tidal wetting and drying and salt weathering was modelled for 6 micro to megatidal environments the model used published tidal elevation dependent weathering and erosional data from 1 to 3 year experiments conducted on more than 2000 sandstone argillite and basalt samples from eastern canada the model analysed annual tidal predictions to convert the weathering data into slope recessional units realistic model profiles with notches at the high tidal level were produced within the 3000 6000 year period since the sea attained its present level there were up to 4 cycles of notch formation and collapse during this time in the rapidly eroding sandstones and a smaller number in the argillites notch morphology was affected by the tidal range the rock type and the initial slope gradient but the maximum depth of the notch before collapse controlled only the number and frequency of the collapse events continuous positive and negative changes in rsl extended the notches in the vertical plane according to the rate and direction upwards or downwards of these changes a distinct series of notches can develop from episodic changes in rsl but the survival of older notches and consequently their utility as palaeosea level indicators depends upon such factors as their elevation with respect to the present tidal range

rapid sea level changes at the close of the last interglacial substage 5e recorded in bahamian island geology rapid and abrupt relative sea level changes within the last interglacial substage 5e are recorded in the island geology of the tectonically stable bahamas from 132 to 118 ka reef growth reached a maximum elevation near 2 m as indicated by fossil reef elevation across the platform whereas bioeroded notches are incised in coastal cliffs as high as 6 m the end of the interval is characterized by voluminous eolianites exhibiting palm tree and frond impressions it is inferred that sea level for most of the interval remained near 2 m restraining reef growth and that the notch at 6 m represents a rapid and brief excursion just before the close of the substage the subsequent fall must have been rapid in order to leave the notch profile intact and mobilize windward lagoon ooids into dunes before cementation could anchor them in order to explain the rapid rise to 6 m glacial surging is invoked the subsequent fall also rapid may be a consequence of the surge flooding high latitudes and providing enough moisture to initiate reglaciation and drawdown

geochemistry and genesis of the lengenbach pb zn as tl ba mineralisation binn valley switzerland the lengenbach pb zn as tl ba mineralisation is located in triassic dolostones of the penninic zone in the swiss alps where alpine metamorphism reached upper greenschist to lower amphibolite grade geochemical data are used to constrain the origin of this unique occurrence two metamorphic redox environments are present the as iii rich zone is controlled by barite pyrite while the reduced zone contains graphite or pyrrhotitepyrite and formally zerovalent as the as iii rich zone is characterised by a mineral assemblage consistent withfo2 in the stability field of barite pyrite an as pb tl rich sulphide melt coexisted with a hydrothermal fluid at 300 c in this zone mineralised dolostones are anomalous in as pb ag tl hg zn ba cd fe cu mo u v b ga cr and possibly sri and au in order of decreasing enrichment as pb and zn are present in the 0 1 to 1 range tl and ag reach several hundred ppm uraninite is concentrated in silicate rich bands and yields a late alpine u pb age of 18 5 0 5 ma pb and s isotopic variations are interpreted by metamorphic overprinting and re equilibration within an isochemically metamorphosed mineralisation hydrothermal sulphides are more strongly affected by uranogenic pb than massive pb as sulphides representing a former sulphide melt the least overprinted mineralisation is characterised by206pb 204pb 18 44 18 56 207pb 204pb 15 60 15 75 208pb 204pb 38 44 38 84 and 34s sulphide 25 2 s isotopic variations are largely a result of sulphide sulphate re equilibration yielding temperatures of 450 30 c 87sr 86sr ratios of mineralised samples are lower than or equal to host dolostones precluding major infiltration of basement derived fluids during alpine metamorphism the sr source 87sr 86sr close to 0 708 probably was seawater with a radiogenic detrital mineral component the genesis of the unique lengenbach mineralisation is interpreted as the result of isochemical metamorphic overprinting of a carbonate hosted stratiform sulphide mineralisation well crystallised sulphide minerals in fissures and druses formed during retrograde cooling of a sulphide melt in equilibrium with a hydrothermal fluid the primary mineralisation was probably formed at or close below the sea floor and fed by sulphide poor hydrothermal fluids sulphide was largely derived from seawater by open system bacterial sulphate reduction u v and mo may be seawater derived

origin of the triassic qilinchang pb zn deposit in the western yangtze block sw china insights from in situ trace elemental compositions of base metal sulphides abstract the qilinchang pb zn deposit 5mt of sulphide ore at mean grades of 2 3 9 2 pb and 2 7 22 5 zn is hosted in early carboniferous carbonate rocks and mainly controlled by ne ns and nw trending structural belts between the xiaojiang and zhaotong qujing buried faults ore minerals are sphalerite galena pyrite chalcopyrite and marmatite whereas gangue minerals are dolomite calcite and quartz three generations of pyrite are recognized these include fine grained anhedral pyrite py i medium grained anhedral to subhedral hydrothermal pyrite py ii and coarse grained subhedral to euhedral hydrothermal pyrite py iii while the sphalerite occurs in two forms as fine grained intergrown with galena and associated with py i and py ii laser ablation inductively coupled plasma mass spectrometry la icp ms analysis was performed to evaluate trace element compositions of pyrite and sphalerite from different generations of ores py i has relatively higher concentrations of mg mn co ni and tl py ii in cu as se mo and sb relative to pyrite of other generations the contents of trace elements in py iii are variable but significantly enriched in ti v bi ag and pb compared to py i and py ii this variation indicates that these elements occur as micro mineral inclusions of possible ag pb bearing phases sphalerite of stage i has higher concentrations of mn fe co ni cu ga ge as ag cd in sb hg and pb than stage ii these elements are homogeneously distributed in all samples analyzed the incorporation of these elements is primarily through simple substitution mechanisms e g 2zn2 cu in3 as indicated from binary plots principal component analyses pca applied to la icp ms dataset for pyrite reveal two main clusters py i enriched in ni co and as py ii and py iii high in with v mn cu zn se mo ag sb au and bi likewise the pca also confirms two clusters of elements for sphalerite ge cu as sb ag fe and cd corresponding to sph i and in sn and ga corresponding to sph ii py i has higher co ni ratio ranging from 0 04 to 1 6 compared to py ii and py iii having co ni ratios from 0 to 0 706 and 0 0 696 respectively we report that the pyrites from the qilinchang deposit have co ni ratios slightly lower than typical mississippi valley type mvt deposits 0 2 7 2 and different from iron oxide copper gold iocg and porphyry cu deposits considering these geochemical signatures it can be suggested that the qilinchang deposit was not related to magmatic activities we thus propose that the ore forming fluids responsible for the formation of the deposit were generated from a low temperature environment similar to typical mvt deposits