palustrine carbonates and the florida everglades towards an exposure index for the fresh water environment abstract palustrine carbonates are shallow fresh water deposits showing evidence of subaqueous deposition and subaerial exposure these facies are common in the geological record the intensity of modification is highly variable depending on the climate and the length of emergence palustrine limestones have previously been interpreted as marginal lacustrine deposits from fluctuating low salinity carbonate lakes but several problems remain with existing facies models 1 palustrine carbonates possess a lacustrine biota but commonly display fabrics similar to those of calcretes and peritidal carbonates 2 the co occurrence of calcrete horizons and karst like cavities is somewhat unusual and appears to indicate contemporaneous carbonate precipitation and dissolution in the vadose zone 3 the dominance of gray colors indicates water saturation apparently inconsistent with the evidence for strong desiccation overprint 4 profundal lake deposits are generally absent from palustrine sequences and sublittoral facies commonly make up only a small proportion of total thicknesses 5 no good modern analogue has been identified for the palustrine environment analogy with the florida everglades suggests a re interpretation of palustrine limestones not as pedogenically modified lake margin facies but as the deposits of extensive very shallow carbonate marshes the distribution of environments in the everglades is determined by the local hydrology reflecting the control of seasonal water level fluctuations and topography climate and topography were the main controls on deposition of ancient palustrine carbonates as in peritidal sequences aggradational cycles are capped by a range of lithologies evaporites desiccation and microkarst breccias calcretes lignite or coal horizons etc permitting interpretation of the climate careful analysis of lateral facies variations may permit reconstruction of subtle topography consideration of the florida everglades as a modern analogue for the palustrine environment has suggested the development of an exposure index for fresh water carbonates

the characteristics and origin of the big lake mafic ultramafic hosted volcanogenic massive sulfide occurrence marathon ontario canada the big lake volcanogenic massive sulfide vms occurrence located in the schreiber hemlo belt in the wawa subprovince of the superior province is hosted in an archean mafic ultramafic metavolcanic sequence lacking felsic volcanic or volcaniclastic rocks discovered in 2006 the occurrence is a subeconomic assemblage of pyrrhotite chalcopyrite sphalerite cobaltite and galena currently defined over an area of 0 5 0 5 km in plan view the mineralized zone is less than 10 m thick with the highest grade intersection containing 4 0 m of 7 5 cu 2 2 zn 138 0 gpt ag and 9 2 gpt au mineralization is hosted in metavolcanic rocks of basaltic to komatiitic basalt compositions the sulfides and spatially associated hydrothermal alteration regionally metamorphosed to chlorite actinolite hornblende biotite phlogopite and anthophyllite are located 5 to 50 m structurally below a thick ultramafic cumulate complex the host sequence to the occurrence is overturned with vms sulfides stratigraphically overlying the ultramafic cumulates rocks stratigraphically below the vms mineralization are transitional to alkaline basalts and komatiitic basalts with convex upward lree and fractionated hree when normalized to primitive mantle basalts stratigraphically overlying the vms mineralization have flat normalized ree patterns la ybcn 1 2 typical of tholeiitic plateau basalts found elsewhere in the wawa belt the lithostratigraphic assemblage at big lake is consistent with an oceanic plateau setting and is interpreted to have formed by eruption of plateau basalts and thick ultramafic flows from a mantle plume unlike vms systems that formed above subvolcanic intrusions 0 5 km below sea floor the big lake vms occurrence may have formed as a result of cooling of the stratigraphically underlying ultramafic cumulates and demonstrates that similar styles of ponded flow driven vms systems albeit small ones may be preserved elsewhere in the superior province or in other archean cratons

the stable isotopic composition of modern soil carbonate and its relationship to climate the oxygen isotopic composition of modern soil carbonate is well correlated with the isotopic composition of local meteoric water the carbon isotopic cycle for co 2 in soils can be described in terms of the proportion of biomass using the c 4 photosynthetic pathway and the co 2 respiration rate of the soil at low soil respiration rates significant atmospheric co 2 mixing can occur in general the carbon isotopic composition of soil carbonate is related to the proportion of c 4 biomass present in soil but soils that freeze to the depth of carbonate formation often have a significant atmospheric component this suggests that freezing of the soil solution should be considered as another important mechanism for soil carbonate formation because of these relationships the isotopic composition of soil carbonate may be a paleoclimatic and paleoecologic indicator in cases in which diagenetic alteration has not occurred

controls on the siting and style of volcanogenic massive sulphide deposits abstract volcanogenic massive sulphide vms deposits form in subaqueous environments from circulating hydrothermal fluids heated by volcanic activity these deposits form as sulphide mounds stratiform exhalative and or replacive bodies and commonly have stockwork vein mineralization in their immediate footwall these various styles are essentially facies of mineralization each one being the product of a particular set of conditions that control the ore forming processes and the consequent geometry and architecture style of the deposits these controls include the physical and or chemical nature of the host rocks the temperature and composition of the hydrothermal fluids and the redox state of the depositional environment the style of exhalative deposits is controlled by the salinity of the vented fluids and the redox state at the seafloor hydrothermal fluids with salinities less than twice that of seawater that vented into open oxic oceanic environments typically formed small mound and chimney complexes unless they were rapidly covered by sediments or volcanic rocks the massive sulphides were rapidly oxidized and partly dissolved by seawater in contrast stratiform sheet like deposits are typically formed in anoxic bottom waters anoxic marine conditions were periodically of global extent particularly prior to 2 4 ga or of a regional nature local anoxic conditions can also be self induced by the exhalation of saline and reducing hydrothermal fluids that ponded in bathymetric depressions such as second or third order basins to form a brine pool these exhalative systems may have been initiated as chimney vent complexes and subsequently overlain by stratiform sulphides formed under the self induced anoxic conditions deposits formed in anoxic environments can be significantly larger than those in oxic settings and this is attributed to several factors that include longer lived hydrothermal circulation more efficient sulphide precipitation and reduced or inhibited oxidation thereof replacement of volcanic and sedimentary strata by sulphide typically occurs within the feeder zones beneath the exhalative mineralization however successions with abundant porous permeable and or reactive rocks such as glassy and or pumiceous volcaniclastic rocks and in some cases limestone favoured the development of large replacive deposits that may have had little surficial expression on the sea floor vms deposits at spreading centres within oceanic crust formed almost exclusively as mounds most of them have not been preserved likely due to oxidation of the sulphides in the prevailing oxic environment and or destruction of oceanic crust during subsequent subduction intra continental rifts arc rifts and back arc rifts commonly have more complexity in their structure and facies architecture and environments and can host all styles of vms mineralization in these settings early extension favoured the formation of restricted basins with ideal conditions for the onset of hydrothermal activity and development of anoxic bottom waters whereas in mature rifts the conditions were less conducive for the formation of regionally extensive anoxic environments formation of replacive deposits was permissible in all settings with porous or reactive subsea floor strata replacive mineralization is the most likely to be preserved in the geological record due to the sulphides being physically shielded from oxidative weathering and mechanical erosion at the seafloor the various styles of vms mineralization can rarely be distinguished using a single criterion in most cases multiple criteria are required mound style mineralization is distinguished by a mound or lens shaped morphology b presence of chimney fragments c presence of abundant sedimented sulphide breccias d location on a stratigraphic boundary ore horizon and e association with a thin horizon or thicker stratigraphic interval of fine grained clastic rocks e g shale mudstone that accumulated at slow sedimentation rates stratiform exhalative mineralization is distinguished by a sheet like morphology prior to deformation b presence of fine grained clastic host rocks that accumulated at relatively slow rates e g mudstone c presence of local or extensive planar stratification replacive mineralization is characterized by a irregular geometry and distribution of sulphide bodies b gradation from massive sulphides to semi massive sulphides and disseminated mineralization with relict textures of the host rock and c originally pumiceous glassy or reactive host rocks emplaced at high depositional rates mass flow deposits lavas carbonate altered mass flow deposits or limestone one deposit or district may comprise two or more of these main styles of mineralization in many cases the main styles of vms mineralization present in a particular region can be predicted from examination of the facies architecture and depositional environments of the host succession recognition of the style s of mineralization that occur in a particular basin or mineral belt enables exploration models to be improved and should influence the strategy of exploration for vms deposits

geochemical and oxygen isotope signature of sea floor alteration associated with a polydeformed and highly metamorphosed massive sulfide deposit ruostesuo central finland massive sulfide deposits in the vihanti pyhasalmi district central finland are hosted by a highly deformed and metamorphosed bimodal volcanic sequence alteration zones that envelop these deposits are composed of cordierite orthoamphibole garnet bearing rocks referred to as cor rocks belonging to upper amphibolite to granulite facies outcrops of mafic and felsic cor rocks mcor and fcor in the vicinity of the ruostesuo zn cu deposit define mappable layers with distinctive metamorphic mineral assemblages orthoamphibole cordierite plagioclase quartz m1cor garnet orthoamphibole cordierite plagioclase quartz m2cor quartz cordierite biotite orthoamphibole cummingtonite garnet plagioclase f1cor and quartz cordierite garnet sillimanite f2cor these rocks are interlayered with or grade into typical amphibolites i e hornblende plagioclase and quartz plagioclase bearing rocks that are interpreted as least altered mafic and felsic metavolcanic rocks respectively whole rock geochemical data for least altered metavolcanic rocks and cor rocks at ruostesuo define three mafic suites primitive basalts basaltic andesites and ferrobasalts and two felsic suites r1 and r2 rhyolites using a combination of high field strength element ratios and rare earth element profiles cor rocks can be assigned to all five volcanic suites calculated mass changes for the majority of exposed cor rocks at ruostesuo are similar to those reported for chlorite quartz assemblages found within the inner core of alteration pipes located below some sea floor massive sulfide deposits relative to least altered precursors mafic cor rocks have gained fe mg s and lost variable amounts of si ca na k rb ba sr and eu which resulted in an average net mass loss of about 10 percent the bulk composition of most altered mafic cor rocks near total loss of ca na k reflects the proportion of chlorite to quartz within the premetamorphic alteration assemblages and the composition of the chlorite mass change results for altered mafic rocks indicate that basalts at ruostesuo were altered by an evolved fe rich hydrothermal fluid at high water rock ratios mass changes for cor rocks of the r2 felsic volcanic suite are similar to those of the mafic rocks enriched in fe mg and depleted in ca na k rb ba sr and eu except for significant additions of si that resulted in net mass gains of 20 to 30 percent felsic cor rocks of the r1 volcanic suite show gains in k rb and ba that are attributed to the formation of premetamorphic sericite during an alteration stage dominated by hydrothermal seawater in comparison to least altered metavolcanic rocks mafic and felsic cor rocks are depleted in 18o with delta 18o values 2 to 5 per mil lower than precursor rocks estimated temperatures of alteration were 270 to 350 c these data indicate that the signature of a high temperature 300 c sea floor hydrothermal upflow zone is preserved within upper amphibolite to granulite facies rocks at ruostesuo the stratigraphic boundary between strongly chloritized mafic volcanic rocks and silicified felsic volcanic rocks marks a transition from net mass losses associated with hydrothermal fluid dominated alteration to net mass gains associated with seawater dominated alteration silicification at or near the boundary between mafic and felsic volcanic rocks may have been the result of conductive cooling or mixing with seawater from above in the absence of textural or crosscutting relationships indicative of a younging direction a stratigraphic model is proposed on the basis of the above geochemical constraints altered basalts at ruostesuo represent the exposed base of a chloritic stockwork zone that passes upsection into altered felsic volcanic rocks that host massive zn cu sulfides this stratigraphic model has significance for the interpretation of other massive sulfide deposits in the vihanti pyhasalmi district and exploration strategies that couple chemostratigraphy with mass change results more significantly the preservation of premetamorphic oxygen isotope values for strongly metamorphosed and locally migmatitic cor rocks indicate that oxygen isotope mapping is a viable exploration tool in the district and in other mineralized upper amphibolite to granulite facies terranes worldwide

petrology geochemistry and oxygen isotope interpretation of felsic volcanic and related rocks hosting the brunswick 6 and 12 massive sulfide deposits brunswick belt bathurst mining camp new brunswick canada the large brunswick massive sulfide deposits brunswick 6 and 12 and austin brook are hosted in the lower part of the middle ordovician bimodal volcano sedimentary tetagouche group along the autochthonous eastern margin of the bathurst mining camp the footwall rocks of the nepisiguit falls formation are relatively homogeneous quartz and alkali feldspar porphyritic crystal rich and matrix supported tuffs with a cryptocrystalline glassy to granular microcrystalline groundmass the fine to coarse grained crystal rich tuffs and tuffaceous sedimentary rocks are thickest 500 m beneath the deposits possibly due to a basinal accumulation of pyroclastic flow material the brunswick horizon massive sulfide deposits and associated exhalite algoma type iron formation formed after a period of felsic pyroclastic volcanism nepisiguit falls formation and before the onset of the overlying thick succession of intercalated rhyolite flows tuffs tuffites and hyalotuffs flat landing brook formation the footwall and hanging wall felsic volcano sedimentary rocks are variably altered which occurred mainly during the syngenetic mineralizing event rocks with minimal evidence of alteration and or tectonic fabric development however allow some interpretation of the major element variations in the least altered suite the sio 2 contents range from 68 to 72 wt percent with intermediate alkali element contents and low fe and mg contents typical of calc alkaline rhyolites weak regional silicification is irregularly distributed in the upper parts of the nepisiguit falls rocks but also in the flat landing brook rocks however there is considerable mobility of na k fe and mg as well as numerous other minor and trace elements as a result of albitization sericitization chloritization and carbonatization reactions associated with vent related and local seawater related alteration processes as observed in earlier alteration studies in the camp there is an antipathetic relationship between sericite and chlorite with chlorite predominant near the deposits

late early permian continental ichnofauna from lake kemp north central texas usa abstract continental trace fossils of early permian age are well known in the western united states from wolfcampian asselian to artinskian strata but few examples are known from leonardian kungurian deposits a substantial ichnofauna from strata of the lower part of the clear fork formation at lake kemp baylor county texas augments the meager north american record of leonardian continental trace fossil assemblages ichnofossils at lake kemp occur in the informally named craddock dolomite member of the clear fork formation which is 12 15 m above the local base of the clear fork the trace bearing stratum is an up to 0 3 m thick laminated to flaser bedded dolomitic siltstone that also contains mud cracks raindrop impressions microbially induced mat structures and some land plant impressions we interpret the craddock dolomite member as the feather edge of a marine transgressive carbonate deposit of an irregular coastline marked by shallow bays or estuaries on the eastern shelf of the midland basin and the trace fossil bearing stratum at lake kemp is an unchannelized flow deposit on a muddy coastal plain the fossil site at lake kemp yields a low to moderately diverse fauna of invertebrate and vertebrate traces a sparse invertebrate ichnofauna consists of arthropod feeding and locomotion traces assigned to walpia cf w hermitensis white 1929 and diplichnites gouldi gevers in gevers et al 1971 tetrapod footprints are most common and assigned to batrachichnus salamandroides geinitz 1861 cf amphisauropus kablikae geinitz and deichmuller 1882 and dromopus lacertoides geinitz 1861 which represent small temnospondyl seymouriamorph and basal sauropsid trackmakers both the traces and sedimentary features of the fossil horizon indicate a freshwater setting at the time of track formation and the trace assemblage represents the scoyenia ichnofacies and the batrachichnus ichnofacies in an overbank environment with sheet flooding and shallow ephemeral pools on an extensive coastal plain the lake kemp tetrapod track assemblage is characteristic of the global early permian tetrapod ichnofauna found in red beds which is dominated by a handful of ichnogenera that include batrachichnus limnopus amphisauropus dromopus varanopus hyloidichnus ichniotherium and dimetropus which are the tracks of temnospondyls seymouriamorphs diadectomorphs pelycosaurs captorhinomorphs and araeoscelids the lake kemp tracks also further document the continuity of the ichnogenera batrachichnus amphisauropus and dromopus from wolfcampian into leonardian time and thus support the concept that wolfcampian and leonardian red bed tetrapod footprints represent a single biostratigraphic assemblage

climate and vegetation history of the midcontinent from 75 to 25 ka a speleothem record from crevice cave missouri usa four missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago ka the thorium 230 dated records reveal that between 75 and 55 ka the midcontinental climate oscillated on millennial time scales between cold and warm and vegetation alternated among forest savanna and prairie temperatures were highest and prairie vegetation peaked between 59 and 55 ka climate cooled and forest replaced grassland at 55 ka when global ice sheets began to build during the early part of marine oxygen isotope stage 3

drivers of precipitation stable oxygen isotope variability in an alpine setting snowy mountains australia natural archives that preserve a stable isotopic signature are routinely used to reconstruct palaeoenvironmental conditions isotopic values of precipitation are known to be influenced by factors such as the amount and type of precipitation moisture pathway landscape and terrain factors and processes associated with precipitation formation and deposition this study investigates oxygen isotopic variability using real time rain and snow precipitation data from a moderate altitude 2250 m above sea level southern hemisphere alpine environment where the causes of isotopic variability are largely unknown previous research at global network of isotopes in precipitation sites skewed toward rain precipitation low altitude predominantly coastal locations identified amount effects as the dominant explanation of isotopic variability in southern australia this study based on within and between event real time sampling finds that the origin of moisture and terrain effects are the dominant cause of isotopic variability in this alpine region with little evidence of amount effects rainfall that originated from similar southern ocean latitudes showed a consistent moderate isotopic signature 18o 6 5 to 8 depleted isotopic signatures are associated with prefrontal activity and intense circulation such as east coast lows localized thunderstorms have a more neutral isotopic signature a windward to leeward depletion 0 5 18o and an elevation impact 0 5 18o 100 m 1 were found also these results have significant implications for understanding atmospheric drivers of isotopic variability from which oxygen isotope based palaeoclimate reconstruction is informed in regions with complex topography and geographically diverse moisture pathways such as the australian alps

interpretation of marine and freshwater paleoenvironments in permo carboniferous deposits article i nfo the freshwater criteria of gray gray j 1988 evolution of the freshwater ecosystem the fossil record palaeogeogr palaeoclimatol palaeoecol 62 1 214 are discussed relative to north american permo carboniferous deposits the faunas of the permo carboniferous basins of north america are compared with those from europe they are very similar organisms which live or lived in the aquatic environment can only characterize this environment terrestrial animals and plants are extraneous to the aquatic environment the best way of interpreting the environment is to compare with contemporaneous aquatic faunas myxinids acritarchs polychaetes and some ostracodes are marine forms spirorbiform microconchids spirorbis and some foraminifers are brackish water indicators based on faunal comparison the permo carboniferous deposits of north america and europe are interpreted as either marine or marine influenced

elevated and variable values of 13c in speleothems in a british cave system 13c isotope variations in speleothems have been investigated for samples from the british isles where plants which use the hatch slack or c4 photosynthetic pathway are not present the range of 13c expected in speleothem carbonate formed in isotopic equilibrium with soil co2 derived from the overlying c3 vegetation should thus fall in the range 12 to 6 forty one actively growing speleothem samples from low discharge sites were analysed from stump cross caverns yorkshire england ten percent have 13c greater than 6 in addition a large range of 13c was observed 8 06 1 38 a 1 variability of 17 with adjacent samples having 13c differing by a maximum of 4 74 similar findings were obtained from a review of analyses of late quaternary speleothem samples from the british isles with 75 of flowstone samples and 57 of high flow stalagmite samples exhibiting elevated 13c three possible processes are proposed as possible causes of elevated 13c in speleothems firstly fractionation may occur between the stalactite and stalagmite due to evaporation or degassing secondly degassing of the groundwaters may have occurred within the aquifer before reaching the cave void allowing release of some co2 from the water whilst remaining saturated in calcium finally the elevated 13c may be due to short water residence times in the soil such that equilibrium between soil water and soil co2 is not reached evidence presented here demonstrates that any one of these mechanisms may be important in the karst areas of the british isles caution is needed before interpreting the 13c signal within speleothems in terms of palaeovegetation

volcaniclastic gravity flow deposits in the dezadeash formation jura cretaceous yukon canada implications regarding the tectonomagmatic evolution of the chitina arc in the northern cordillera of north america abstract the chitina arc in the northern cordillera of north america evolved during the accretion of the wrangellia composite terrane to the western margin of north america in the jurassic and cretaceous the dezadeash formation a 3000 m thick sequence of deepwater turbidites in southwestern yukon was deposited as a submarine fan in a backarc basin to the chitina arc only limited geochemistry of altered volcanic rocks associated with the arc are available from southern alaska however three thick volcaniclastic beds occur in the dezadeash formation these consist of fine to medium grained vitric to crystal tuffs that are interpreted as resedimented syn eruptive volcaniclastics a u pb zircon age 149 4 0 3 ma indicates they are contemporaneous with the chitina arc petrographic examination shows the volcaniclastic rocks are altered mainly by albite and locally calcite with a chemical index of alteration suggesting the rocks are relatively unweathered or have undergone only incipient weathering harker diagrams indicate that cao k 2 o and rb were mobile based on the th vs co compositional diagram the volcaniclastic rocks are classified as dacites and according to various trace element plots they are calk alkaline and adakite like in composition the volcaniclastic rocks plot in the active continental margin field on a variety of tectonic discriminant diagrams and chondrite normalized multi element plots display parallel listric shaped profiles with significant light rare earth element enrichment and minor heavy rare earth element enrichment sm nd systematics indicate the volcaniclastic rocks represent mixing of a depleted mantle source and an older crustal source these data suggest mainly slab dehydration with low pressure fractionation controlled by amphibole with possibly minor input by slab melting the chitina arc has previously been interpreted as an oceanic island arc and the continental arc signature of volcaniclastic rocks in the dezadeash formation together with a continental arc signature of altered volcanic rocks in southern alaska is attributed to arc magmas erupting through paleozoic volcanic sedimentary and plutonic rocks of the wrangellia composite terrane proxying for continental crust

sims oxygen isotopes indicate phanerozoic fluids permeated a precambrian gold deposit abstract the reef deposit is an anomalous au cu occurrence in the paleoproterozoic terranes of northern wisconsin better known as host to significant cu zn volcanogenic massive sulfide vms deposits previous work using lead isotopes and fluid inclusions has identified a protracted development of the mineralization from initial formation as the root zone veins of a vms deposit during the penokean orogeny 1 9 1 8 ga with the most recent mineralization remobilization activity associated with late paleozoic mississippi valley type mvt fluid flow haroldson et al 2018a 2018b here we use the oxygen isotope history of the reef deposit to verify and further examine the deposit s protracted development laser fluorination oxygen isotope measurements of primary mineralized quartz veins range in 18o from 6 8 to 10 0 vsmow and a trend is observed of increasing 18o values of parallel vein zones along a 400 m traverse from northwest to southeast likely from a temperature gradient during initial formation temperature estimates for a vms deposit setting 230 to 400 c are consistent with a hydrothermally shifted formation fluid using seawater 18o estimates during the penokean orogeny and evolving to higher 18o by incorporation of magmatic fluids or interaction with local crust in situ oxygen isotope measurement by secondary ion mass spectrometer sims of cross cutting quartz and carbonate range in 18o from 19 4 to 28 4 for quartz 25 3 to 28 1 for dolomite and 9 6 to 29 3 vsmow for calcite high 18o values 19 are measured in a crustiform textured quartz stockwork microveinlet in dolomite observed in late carbonate microveinlets and calcite in settings associated with the late quartz and dolomite and a separate calcite only setting directly linked with gold mineralization remobilization

geochemistry and paleotectonic setting of felsic volcanic rocks in the finlayson lake volcanic hosted massive sulfide district yukon canada the finlayson lake volcanic hosted massive sulfide vhms district represents one of canada s most recent vhms discovery regions with 34 million metric tons mt of massive sulfide mineralization found since the mid 1990s felsic volcanic rocks are associated with three units the fire lake unit the kudz ze kayah unit and the wolverine succession significant accumulations of polymetallic felsic vhms deposits kudz ze kayah gp4f and wolverine have only been discovered in the kudz ze kayah unit and wolverine succession to date in the hanging wall of the money creek thrust felsic volcanic and high level intrusive rocks in the fire lake unit have calc alkalic and tholeiitic affinities with low high field strength element hfse contents and intermediate zr sc 9 4 43 4 and zr tio2 254 864 ratios these rocks are interlayered with mafic rocks with arc geochemical signatures to date devoid of significant vhms mineralization and represent bimodal magmatism within an evolving devonian mississippian continental arc system the kudz ze kayah unit in the footwall of the money creek thrust stratigraphically overlies the fire lake unit and consists of felsic volcanic rocks with high hfse contents within plate a type signatures and high zr sc 15 3 190 3 and zr tio2 630 2 185 ratios the kudz ze kayah unit felsic rocks are crosscut and overlain by alkalic mafic rocks are associated with abundant carbonaceous sedimentary rocks and represent magmatism within a devonian mississippian ensialic back arc rift basin environment the wolverine succession unconformably overlies the kudz ze kayah unit felsic rocks below the wolverine deposit have geochemical attributes similar to the kudz ze kayah unit with high hfse contents within plate a type signatures and high zr sc 29 9 84 2 and zr tio2 391 1 220 ratios in contrast aphyric rhyolite flows in the hanging wall of the deposit have much lower hfse contents and the lowest zr sc 3 5 27 7 and zr tio2 181 591 ratios in the district all the felsic rocks of the wolverine succession are interlayered with abundant carbonaceous sedimentary rocks and are overlain by midocean ridge basalt morb like basaltic rocks the wolverine succession is interpreted to have formed within an early mississippian ensialic back arc basin environment that eventually evolved to sea floor spreading the variation in the hfse budgets of the felsic rocks of the finlayson lake district likely reflects variations in the source and or temperature of crustal melting in particular felsic rocks of the fire lake unit have higher nb ta and lower ti sc ratios than other volcanic rocks in the district suggesting possible derivation from mafic crustal sources and or lower crustal fusion temperatures the kudz ze kayah unit and footwall rocks to the wolverine deposit are inferred to have formed from high temperature partial melting of continental crust the hanging wall aphyric rhyolites from the wolverine deposit may have formed from either lower temperature continental crustal melting or may have been derived from the mixing of hfse depleted n morb mafic magmas and evolved continental crust polymetallic felsic volcanic associated vhms deposits within the finlayson lake district are preferentially associated with hfse enriched felsic rocks with high zr sc 15 3 190 3 and zr tio2 391 2 105 ratios the hfse and rare earth element ree systematics of vhms associated felsic rocks of the finlayson lake district are different from prospective felsic rocks from archean vhms environments in the superior province and are displaced toward higher zr y and la ybn ratios their hfse and ree systematics are similar to many phanerozoic vhms environments in particular those at least partially to fully underlain by evolved continental crust the geochemical differences between the felsic rocks of the finlayson lake district and those from archean vhms environments most likely reflect differences in the substrates from which the felsic rocks were derived e g evolved versus juvenile

trace elements in speleothems as recorders of environmental change speleothems are now established as important palaeoenvironmental archives and contain a number of suitable proxies although trace elements have been much less widely used than oxygen and carbon isotopes the complexity of the cave environment helps to explain this since the fluids from which speleothems form vary greatly in composition in space even within a cave chamber seasonally and over longer periods understanding the forcing factors for this variability is the key to decoding the significance of the trace element records a variety of techniques are available for trace element work and it is important to understand the strengths and limitations of each and also to seek an understanding e g by micro imaging techniques of whether the elements are associated with inclusions in the caco3 or are isolated within the crystal lattice for some elements there is a more or less predictable relationship between element ratios to ca in the water and in the calcite individual trace elements may be derived from atmospheric deposition superficial deposits or bedrock and can be recycled in soil processes before being transferred to the cave some components show an instantaneous response to water infiltration whereas others are only leached by slow flowing seepage waters changing in the proportion of water from fracture fed and seepage flow aquifer compartments is an important factor in influencing trace element supply high flows lead to higher fluxes of soil derived colloidally transported elements conversely under relatively dry conditions degassing of co2 results in prior calcite precipitation upflow of the site of speleothem deposition and leads to higher ratios of sr ca and mg ca some trace element variations in speleothems over time are induced during crystal growth whereby faster growth leads to a greater departure from equilibrium element partitioning despite the demonstrated temperature dependence of mg partitioning into calcite attempts at deriving palaeotemperature records from speleothems have been so far confounded by variations in solution mg ca and or crystallographic effects a number of case studies have effectively used trace elements such as speleothem mg as records of palaeo aridity using supporting arguments from modern monitoring or covariations with other parameters such as stable isotopes sr and u isotopes can also be indicators of palaeohydrology although sr isotope variations can also reflect varying aeolian input considerable progress has been made in decoding the meaning of annual trace element variations using criteria for understanding dripwater hydrology and ph this should lead in the future to more specific interpretations of how seasonality evolves through time

quaternary climatic instability in south east australia from a multi proxy speleothem record milankovitch scale quaternary climatic oscillations within south east australia are known to be characterized by relatively arid glacial and wet interglacial stages however terrestrial proxy records of environmental change are scarce based largely on river terraces dune sediments and pollen sequences here we present a speleothem based palaeoclimate record from yarrangobilly caves south east australia the oxygen isotopic composition of calcite 18ocalcite is taken to represent rainfall amount and used as an aridity index high resolution trace element profiles and uv fluorescence support interpretations based on 18ocalcite allowing further designation of key phases of speleothem growth into periods of relative aridity and moisture excess a hiatus of approximately 37 ka duration divides the record into two key phases of growth which can be mapped onto marine isotope stages 5c a and 3 respectively increasing aridity in the latter half of mis 5 led to cessation of speleothem growth for the duration of mis 4 growth recommences during mis 3 associated with greater moisture availability enhanced vegetation and augmented biogeochemical cycling this speleothem record provides a unique context of terrestrial environmental change and depicts hydrological conditions which fluctuate markedly over the 70 ka period covering the time of megafauna extinction and human arrival on the continent

in situ oxygen isotope micro analysis of faunal material and human teeth using a shrimp ii a new tool for palaeo ecology and archaeology a sensitive high resolution ion microprobe shrimp ii has been used to make high spatial resolution in situ micro analyses of oxygen isotopes in fish otoliths and teeth from fossil herbivores and a neanderthal large intra tooth variations in the oxygen isotopic composition up to 9 were observed in the enamel of herbivores from the neanderthal fossil site of payre consistent with preservation of seasonal cyclicity the range of isotopic compositions observed in neanderthal tooth enamel was much smaller w3 possibly the result of a longer enamel maturation time averaging out variability an archaeological otolith from a preceramic site in northern peru exhibited marked changes in d 18 o over life due either to the fish occasionally migrating from the sea to a lower salinity habitat or to short lived rises in sea water temperature a fish otolith from australia s willandra lakes world heritage area showed clear seasonal variations but also a general trend towards isotopically heavier and more saline water as indicated by higher d 18 o and sr ca values resulting from increased evaporation the results of these case studies are compared to results of oxygen isotope analysis using more conventional methods and demonstrate the ability of the shrimp ii to provide precise high spatial resolution in situ oxygen isotope analyses of a variety of biogenic materials this approach has major advantages over conventional methods it can provide rapid micro scale isotopic analyses of sub permil precision without the need for chemical preparation of the sample

ion microprobe analysis of oxygen isotope ratios in granulite facies magnetites diffusive exchange as a guide to cooling history ion microprobe analysis of magnetites from the adirondack mountains ny yields oxygen isotope ratios with spatial resolution of 2 8 m and precision in the range of 1 1 sigma these analyses represent 11 orders of magnitude reduction in sample size compared to conventional analyses on this material and they are the first report of routinely reproducible precision in the 1 per mil range for analysis of 18o at this scale high precision micro analyses of this sort will permit wide ranging new applications in stable isotope geochemistry the analyzed magnetites form nearly spherical grains in a calcite matrix with diopside and monticellite textures are characteristic of granulite facies marbles and show no evidence for retrograde recrystallization of magnetite magnetites are near to fe3o4 in composition and optically and chemically homogeneous a combination of ion probe plus conventional brf5 analysis shows that individual grains are homogeneous with 18o 8 9 1 smow from the core to near the rim of 0 1 1 2 mm diameter grains depth profiling into crystal growth faces of magnetites shows that rims are 9 depleted in 18o these low 18o values increase in smooth gradients across the outer 10 m of magnetite rims in contact with calcite these are the sharpest intracrystalline gradients measured to date in geological materials this discovery is confirmed by bulk analysis of 150 350 m diameter magnetites which average 1 2 lower in 18o than coarse magnetites due to low 18o rims conventional analysis of coexisting calcite yields 18o 18 19 suggesting that bulk 18o cc mt 9 3 and yielding an apparent equilibration temperature of 525 c over 200 c below the temperature of regional metamorphism consideration of experimental diffusion data and grain size distribution for magnetite and calcite suggests two contrasting cooling histories the data for oxygen in calcite under hydrothermal conditions at high p h2o indicates that diffusion is faster in magnetite and modelling of the low 18o rims on magnetite would suggest that the adirondacks experienced slow cooling after grenville metamorphism followed by a brief period of rapid cooling possibly related to uplift conversely the data for calcite at low p h2o show slower oxygen diffusion than in magnetite modelling based on these data is consistent with geochronology that shows slow cooling through the blocking temperature of both minerals suggesting that the low 18o rims form by exchange with late low temperature fluids similar to those that infiltrated the rock to serpentinize monticellite and which infiltrated adjacent anorthosite to form late calcite veinlets in either case the ion microprobe results indicate that two distinct events are recorded in the post metamorphic exchange history of these magnetites recognition of these events is only possible through microanalysis and has important implications for geothermometry

high resolution isotopic records from corals using ocean temperature and mass spawning chronometers abstract we present a 6 year long 1978 1984 18 o and 13 c record from a great barrier reef pandora reef porites lutea coral based on near weekly sample intervals a sampling technique was designed to minimise any smoothing or distortion of the isotopic record due to complex coral growth calyx architecture and calcification at depth within the tissue layer the arrival time of the mid winter minimum sea surface temperature is very consistent 2 weeks near pandora reef and provides an annual time marker offering more precision than the traditional density band chronometer the improved chronology and high resolution record demonstrate that signal distortion in porites due to calcification within the tissue layer and variable intra annual coral extension is generally negligible also confirmed is that the arrival time of monsoonal floods is precisely preserved 1 week within the skeleton of porites the sensitivity of weekly sampling allows the detection of a subtle warm to cool sea surface temperature anomaly which preceded by more than one year a similar temperature anomaly associated with the 1982 83 el nin o in the east pacific sharply higher 13 c values coincide with the time of the annual coral mass spawning event in the great barrier reef recognition of this mass spawning signal should simplify the interpretation of coral 13 c records and provides an additional precise time marker with which to adjust chronologies when intra annual coral extension is not constant

petrology and u pb geochronology of footwall porphyritic rhyolites from the wolverine volcanogenic massive sulfide deposit yukon canada implications for the genesis of massive sulfide deposits in continental margin environments porphyritic rhyolite sills form an important component of the footwall of the wolverine volcanogenic massive sulfide vms deposit yukon canada and occur proximal to mineralization in the immediate deposit area wolverine lynx zone and at similar stratigraphic levels along strike fisher puck and sable zones porphyritic rhyolites are of two types an older quartz feldspar porphyritic qfp rhyolite suite and a younger feldspar porphyritic fp suite both the qfp and fp suites of intrusions are semiconcordant suggesting a silllike morphology and are altered and crosscut by veinlet mineralization suggesting that they are pre to synmineralization the margins of qfp suite of intrusions contain minor xenoliths of surrounding shales and poorly developed chilled margins suggesting emplacement into partially consolidated sedimentary rocks whereas the fp suite of intrusions shows well developed chilled margins indicative of emplacement into fully solidified sedimentary rock these features suggest that the qfp suite of intrusions represents an older phase of rhyolitic magmatism whereas the fp suite represents a younger event this is supported by u pb zircon ages which indicate a 352 4 1 5 ma emplacement age for the fp suite and a 347 to 346 ma emplacement for the fp suite two ages at 347 8 1 3 and 346 0 2 2 ma both suites of porphyries have inherited proterozoic zircon and have ratios of la smucn 1 and nb thucn 1 ucn upper continental crust normalized indicating derivation from and or extensive interaction with ancient upper continental crustal materials the fp suite however has elevated high field strength element hfse and rare earth element ree contents high zircon saturation temperatures and higher nb ta ratios and lower ti sc ratios than the qfp suite these features are interpreted to reflect that the fp suite of magmas was hotter 900 c melts with a greater mantle component in their genesis both suites however are interpreted to have formed due to basaltic upwelling crustal melting and crust mantle mixing during ensialic back arc basin activity the presence of mantle heat within the wolverine basin from 352 to 347 to 346 ma a minimum of 5 m y suggests that sustained mantle heat flow was critical to the genesis of the wolverine porphyries it is also suggested that this sustained mantle heat was responsible for the wolverine hydrothermal system and that upwelling mantle may be essential in providing the heat to drive hydrothermal systems even in continental margin type vms environments e g bathurst iberian pyrite belt the wolverine porphyries are among the most hfse and ree enriched felsic rocks associated with vms mineralization globally the high hfse and ree concentrations in these rocks are interpreted to be due to

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

a high spatial resolution δ18o profile of a speleothem using an ion microprobe the oxygen isotopic composition of a stalactite from the soreq cave israel has been investigated by in situ high spatial resolution ion microprobe analysis the d 18 o record obtained on portions of the stalactite which were deposited during the time interval of 18 14 3 10 8 8 5 and 1 5 0 2 ka has a temporal resolution ranging from f1 to 25 years depending on the deposition rate during the period investigated comparison to results obtained by micro drilling and phosphoric acid reaction gas phase mass spectrometry indicates that the ion microprobe analyses are precise and accurate at the 0 4 0 5xlevel the high resolution of the ion microprobe profile enables the detection of short duration excursions toward low d 18 o values during deglaciation from 18 to 14 3 ka providing further evidence indicating the instability of the glacial climate d 2002 elsevier science b v all rights reserved

sedimentary facies and environmental ichnology of a permian playa lake complex in western argentina abstract a moderately diverse arthropod ichnofauna occurs in permian ephemeral lacustrine deposits of the paganzo basin that crop out at bordo atravesado cuesta de miranda western argentina sedimentary successions are interpreted as having accumulated in a playa lake complex deposits include three sedimentary facies a laminated siltstone and mudstone b current rippled cross laminated very fine grained sandstone and c climbing and wave rippled cross laminated fine grained sandstone deposited by sheet floods under wave influence in the playa lake complex analysis of facies sequences suggests that repeated vertical facies associations result from transgressive regressive episodes of variable time spans the bordo atravesado ichnofauna includes cruziana problematica diplocraterion isp cf diplopodichnus biformis kouphichnium isp merostomichnites aicunai mirandaichnium famatinense monomorphichnus lineatus palaeophycus tubularis umfolozia sinuosa and umfolozia cf u longula the assemblage is largely dominated by arthropod trackways and represents an example of the scoyenia ichnofacies trace fossils are mostly preserved as hypichnial ridges on the soles of facies c beds being comparatively rare in facies a and b ichnofossil preservation was linked to rapid influx of sand via sheet floods entering into the lake four taphonomic variants types 1 4 are recognized each determined by substrate consistency and time averaging type 1 is recorded by the presence of low density assemblages consisting of poorly defined trackways which suggests that arthropods crawled in soft probably slightly subaqueous substrates type 2 is represented by low to moderate density suites that include sharply defined trackways commonly associated with mud cracks suggesting that the tracemakers inhabited a firm desiccated lacustrine substrate type 3 displays features of types 1 and 2 and represents palimpsestic bedding surfaces resulting from the overprint of terrestrial ichnocoenoses over previously formed softground suites type 4 differs from type 2 only in that assemblages display a high density of traces recorded by numerous superimposed trackways which suggests a major time gap of subaerial exposure before sheet flood entrance therefore type 4 surfaces are mostly interpreted as track imprinted omission surfaces

non tetrapod trace fossils from the middle devonian tetrapod tracksite at zachelmie quarry holy cross mountains poland abstract the middle devonian eifelian dolomites exposed in the zachelmie quarry holy cross mountains southern poland contain the earliest fossil record of tetrapods low diversity but unique assemblages of trace fossils characterize the track bearing interval within the lower complex of the wojciechowice formation the reconstructed environment of the trace fossil rich beds includes ephemeral lakes and or shallow water lagoons separated from an open marine area by sparsely vegetated islands and spits the most abundant non tetrapod trace fossils from these beds are large horizontal to vertical burrows and dish circular to oval shaped shallow depressions the burrows are abundant on the upper surfaces of thick dolomicritic beds especially in some palaeosol levels but they are also associated with tetrapod trackways large semi aquatic or terrestrial animals e g arthropods or vertebrates most likely produced these burrows the circular to oval shaped depressions observed on a large surface and other smaller isolated blocks from the same stratigraphical level are interpreted as fish feeding nesting resting traces piscichnus sanctacrucensis isp nov is proposed as a new ichnospecies of the oval shaped fish trace fossil from the middle devonian of poland a single medium sized undichnia specimen a fish swimming trace is associated with the piscichnus traces the described trace fossils provide new insight into the palaeoecology and taphonomy of the middle devonian tetrapod tracksite from poland and clarify remaining controversies regarding the interpretation of some poorly preserved trace fossils from the zachelmie quarry

geochemistry of surface waters associated with an undisturbed zn pb massive sulfide deposit water rock reactions solute sources and the role of trace carbonate abstract we report results of a detailed geochemical study of surface waters from several streams in a small catchment in northern new brunswick canada rocks in the catchment represent metamorphosed greenschist facies felsic volcanic rocks metavolcaniclastic sediments and mafic volcanic rocks no massive carbonate or evaporite lithologies are present thus providing an excellent opportunity to investigate the relative influence of silicate weathering compared to trace carbonate vein and disseminated dissolution and the influence of volcanogenic massive sulfide vms mineralization on surface water chemistry surface waters catchment lithologies and stream sediments were analyzed for a full suite of major and trace elements surface waters are dilute typically 3 type most waters have ca na molar 1 the major ion chemistry of the waters is consistent with binary mixing between silicate weathering and dissolution of trace calcite si ca molar relationships suggest that trace calcic silicates are insignificant compared to calcite as a ca source and po 4 concentrations of waters are too low for apatite to be a major source of ca host rocks have highly variable ca na mg na and k na values complicating the assignment of a silicate end member geochemical modeling indicates that surface waters range from essentially 100 of the na and ca being derived by silicate weathering to being dominantly controlled by trace calcite also consistent with mass balance calculations the cl ca ratios are consistent with the host felsic and mafic metavolcanic rocks as being an important source of cl in addition to precipitation the host lithologies have much larger variations in mg na ca na k na and sr na than the stream sediments and waters and the sediments are shifted to higher mg na and k na and lower ca na than the waters it is remarkable that the waters have such small variations in major ion ratios relative to the host rocks indicating that the controls on solute loads of these streams is more a function of relative elemental solubility ca mg na secondary mineral formation e g mg and k rich clays incongruent dissolution and water rock reactions than end member rock compositions oxidation of massive and disseminated sulfide mineralization accounts for on average 60 of the dissolved sulfate calculations indicate that sulfide oxidation sulfuric acid weathering accounts for around 20 of the cation flux in the watershed on average 12 of the ca and 72 of the mg are derived from silicate weathering although cationic silicate denudation rates are only 1 88 tonnes km 2 year compared to 4 16 tonnes km 2 year for trace carbonate dissolution the total cation denudation rate and co 2 consumption rate are similar to watersheds draining volcanic rocks in the western canadian cordillera

permian tetrapod footprints from the spanish pyrenees abstract paleozoic tetrapod footprints are a common and well known phenomenon in almost all large european countries except for spain here we report on hitherto unpublished vertebrate tracks from permian red beds of the south central pyrenees that with regard to their relative abundance diversity and quality of preservation are suitable to fill this gap of knowledge the described tracks come from two localities in muddy to fine grained sandy alluvial plain deposits in the lower third of the peranera formation of the erill castell basin near les iglesies northern catalonia the tracks can be assigned to five ichnogenera i e batrachichnus woodworth 1900 limnopus marsh 1894 varanopus moodie 1929 hyloidichnus gilmore 1927 and dromopus marsh 1894 that we interpret as footprints of temnospondyls captorhinomorphs and araeoscelids or similarly sized sauropsids with a lacertoid foot pattern this ichnofossil assemblage is most similar to ichnofaunas from the hermit formation of the grand canyon arizona the upper abo and robledo mountains formations of new mexico and the main trace fossil site of the tiddas basin morocco suggesting a late early permian artinskian age for this stratigraphic level of the peranera formation considering the relative abundance and diversity of captorhinomorph footprints the new spanish tracefossil localities may cover the onset of the early permian radiation of non diapsid eureptiles the thick late paleozoic red bed successions of the south central pyrenees have the potential to also bear footprints of otherwise unknown early therapsids so systematic fossil prospecting of this area is strongly recommended

the setting style and role of magmatism in the formation of volcanogenic massive sulfide deposits throughout earth s history all volcanogenic massive sulfide vms hosting environments are associated with specific assemblages of mafic and felsic rocks with distinct petrochemistry petrochemical assemblages indicative of formation at anomalously high temperatures within extensional geodynamic environments in mafic dominated juvenile ophiolitic vms environments there is a preferential association with mafic rocks with boninite and low ti tholeiite mid ocean ridge basalt morb and or back arc basin basalt affinities representing forearc rifting or back arc initiation mid ocean ridges or back arc basin spreading or back arc basins respectively felsic rocks in juvenile oceanic arc environments in archean terrains are high field strength element hfse and rare earth element ree enriched in post archean juvenile oceanic arc terrains felsic rocks are commonly hfse and ree depleted and have boninite like to tholeiitic signatures in vms environments that are associated with continental crust i e continental arc and back arc and dominated by felsic volcanic and or sedimentary rocks evolved environments felsic rocks are the dominant hosts to mineralization and are generally hfse and ree enriched with calc alkalic a type and or peralkalic affinities representing continental arc rifts continental back arcs and continental back arcs to continental rifts respectively coeval mafic rocks in evolved environments have alkalic within plate ocean island basalt like and morb signatures that represent arc to back arc rift versus back arc spreading respectively the high temperature magmatic activity in vms environments is directly related to the upwelling of mafic magma beneath rifts in extensional geodynamic environments e g mid ocean ridges back arc basins and intra arc rifts underplated basaltic magma provides the heat required to drive hydrothermal circulation extensional geodynamic activity also provides accommodation space at the base of the lithosphere that allows for the underplated basalt to drive hydrothermal circulation and induce crustal melting the latter leading to the formation of vms associated rhyolites in felsic dominated and bimodal vms environments rifts also provide extensional faults and the permeability and porosity required for recharge and discharge of vms related hydrothermal fluids rifts are also critical in creating environments conducive to preservation of vms mineralization either through shielding massive sulfides from seafloor weathering and mass wasting or by creating environments conducive to the precipitation of subseafloor replacement style mineralization in sedimented rifts subvolcanic intrusions are also products of the elevated heat flow regime common to vms forming environments shallow level intrusive complexes i e within 1 3 km of the seafloor may not be the main drivers of vms related hydrothermal circulation but are likely the manifestation of deeper seated mantle derived heat i e 3 10 km depth that drives hydrothermal circulation these shallower intrusive complexes are commonly long lived i e millions of years and reflect a sustained thermally anomalous geodynamic environment such a thermally anomalous environment has the potential to drive significant hydrothermal circulation and therefore multi phase long lived subvolcanic intrusive complexes are excellent indicators of a potentially fertile vms environment the absence of intrusive complexes however does not indicate an area of low potential as they may have been moved or removed due to post vms tectonic activity in some cases shallow level intrusive systems contribute metals to the vms hydrothermal system

4 transpressional tectonics lower crust decoupling and intrusion of deep mafic sills a model for the unusual metallogenesis of sw iberia abstract sw iberia is interpreted as an accretionary magmatic belt resulting from the collision between the south portuguese zone and the autochthonous iberian terrane in variscan times 350 to 330 ma in the south portuguese zone pull apart basins were filled with a thick sequence of siliciclastic sediments and bimodal volcanic rocks that host the giant massive sulphides of the iberian pyrite belt massive sulphides precipitated in highly efficient geochemical traps where metal rich but sulphur depleted fluids of dominant basinal derivation mixed with sulphide rich modified seawater massive sulphides formed either in porous reactive volcanic rocks by sub seafloor replacement or in dark shale by replacement of mud or by exhalation within confined basins with high biogenic activity crustal thinning and magma intrusion were responsible for thermal maturation and dehydration of sedimentary rocks while magmatic fluids probably had a minor influence on the observed geochemical signatures the ossa morena zone was a coeval calc alkaline magmatic arc it was the site for unusual mineralization particularly magmatic ni cu and hydrothermal fe oxide cu au ores iocg most magmatism and mineralization took place at local extensional zones along first order strike slip faults and thrusts the source of magmas and iocg and ni cu deposits probably lay in a large mafic ultramafic layered complex intruded along a detachment at the boundary between the upper and lower crust here juvenile melts extensively interacted with low grade metamorphic rocks inducing widespread anatexis magma contamination and further exsolution of hydrothermal fluids hypersaline fluids 18 o fluid 5 4 to 12 were focused upward into thrusts and faults leading to early magnetite mineralization associated with a high temperature 500 c albite actinolite salite alteration and subsequent copper gold bearing vein mineralization at somewhat lower temperatures assimilation of sediments by magmas led in turn to the formation of immiscible sulphide and silicate melts that accumulated in the footwall of the layered igneous complex further injection of both basic and sulphide rich magmas into the upper crust led to the formation of ni cu rich breccia pipes younger 330 to 280 ma peraluminous granitoids probably reflect the slow ascent of relatively dry and viscous magmas formed by contact anatexis these granitoids have w sn and pb zn related mineralization that also shows geochemical evidence of major mantle crust interaction late epithermal hg cu sb and pb zn ag mineralization was driven by convective hydrothermal cells resulting from the high geothermal gradients that were set up in the zone by intrusion of the layered igneous complex in all cases most of the sulphur seems to have been derived from leaching of the host sedimentary rocks 34 s 7 to 20 with only limited mixing with sulphur of magmatic derivation the metallogenic characteristics of the two terranes are quite different in the ossa morena zone juvenile magmatism played a major role as the source of metals and controlled the styles of mineralization in the south portuguese zone magmas only acted as heat sources but seem to have had no major influence as sources of metals and fluids which are dominated by crustal signatures most of the magmatic and tectonic features related to the variscan subduction and collision seem to be masked by those resulting from transpressional deformation and deep mafic intrusion which led to the development of a metallogenic belt with little resemblance to other accretionary magmatic arcs

application of high field strength elements to discriminate tectonic settings in vms environments high field strength element ratios in felsic volcanic rocks reflect the tectonomagmatic evolution of a region th ta th hf ta hf th yb and ta yb ratios collectively help to define the tectonic environment of volcanism separating oceanic arcs active continental margins and within plate volcanic zones on the basis of the above empirical observations the tectonic environments of selected archean and post archean volcanogenic massive sulfide deposits were reexamined published data sets plotted on discriminant diagrams represent twelve volcanogenic massive sulfide vms deposits from two distinct tectonic environments the volcanic rocks of the kuroko deposits japan san nicolas mexico and bathurst new brunswick canada plot within the active continental margin field on all diagrams whereas volcanic rocks from archean deposits of the superior province canada kidd creek kamiskotia geco winston lake mattabi lyon lake noranda selbaie and south bay plot in the within plate volcanic zone field the discriminant diagrams demonstrate that although the chemical character of rhyolites has not changed significantly since the archean the range of geotectonic setting of vms deposits probably has it is suggested that archean deposits most likely formed in an ensimatic rift environment whereas post archean deposits formed in subduction related rift zones of arc environments subduction related rhyolites of vms deposits are variably enriched in th and the light rare earth elements with respect to ta nb and the heavy rare earth elements

geochemistry and u pb dating of felsic volcanic rocks in the riotinto nerva unit iberian pyrite belt spain crustal thinning progressive crustal melting and massive sulphide genesis abstract we present new geochemical sm nd and u pb data on the felsic volcanic rocks containing the world class volcanic hosted massive sulphide deposits in the riotinto nerva unit iberian pyrite belt spain three new u pb ages from older plagioclase quartz phyric dacites and plagioclase phyric rhyolites to youngest plagioclase quartz phyric rhyolites indicate a time span for felsic volcanism ranging from 351 5 0 4 to 345 7 0 6 ma the youngest felsic rocks exhibit lower e nd as well as contrasting ti sr zr hf and eu eu values we interpret that in the riotinto nerva unit crustal melting successively affected shallower more evolved horizons in the crust progressive crustal melting is consistent with current interpretations of the iberian pyrite belt in terms of a late devonian early carboniferous transtensional setting coupled with underplating by basic magma we suggest that low e nd evolved crustal magmatism could be used as a proxy in studies of the genesis of these and possibly other phanerozoic massive sulphide deposits supplementary material details of the analytical methods and whole rock data for basalts are available at http www geolsoc org uk sup18452

comparison of drier to wetter interval estuarine roof facies in the eastern and western interior coal basins usa abstract many of the carboniferous coals in the eastern interior of the us are associated with siliciclastic roof facies that were deposited within a fluvio estuarine transition these facies include a variety of rhythmites some of which exhibit tidal cycles drier interval coals westphalian b c stephanian tend to be more laterally restricted and more commonly are associated with paleovalleys conversely wetter interval coals westphalian d are very widespread and are not restricted to paleovalleys throughout the lake carboniferous wet paleoclimates associated with these coals lead to valley incision during sea level lowstand when large tropical rivers downcut older sediments deposited during previous sea level highstands during subsequent rise of sea level these fluvial valleys were flooded and converted to estuaries where tidal ranges and sedimentation rates were significantly amplified based on modern analogs and interpretation of many examples of carboniferous tidal rhythmites the localized depositional rates in these settings are exceptionally high the estuaries became sediment sinks trapping sediment that is pumped in from both fluvial and marine sources as a result sedimentation readily keeps pace with rising baselevel extensive intertidal flats and shallow subtidal flats are created and prograde over the valley confined mires thick tidal cycles and upright trees some with attached foliage record rapid burial of mires this model is supported with examples of roof facies from the westphalian b c of the eastern interior basin and the stephanian of the western interior basin in these areas facies within each cycle range from well developed extensive paleosols and coals to widespread marine shales or limestones variations in both sea level and climate resulted in a complex history of valley fill during which coals could be developed at any time except during widespread flooding minable low sulfur and low ash coals occur but the coals are relatively thin and discontinuous conversely the westphalian d coals are very widespread and significant peat accumulations were not confined to paleovalleys nonetheless the lowest sulfur coals are related to rapid deposition of roof facies that occurred within the paleovalley whereas high sulfur coals were formed in areas of lower sedimentation rate of roof facies that occurred beyond the confines of the paleovalley

very high frequency and seasonal cave atmosphere pco2 variability implications for stalagmite growth and oxygen isotope based paleoclimate records abstract cave air p co 2 at two irish sites varied dramatically on daily to seasonal timescales potentially affecting the timing of calcite deposition and consequently climate proxy records derived from stalagmites collected at the same sites temperature dependent biochemical processes in the soil control co 2 production resulting in high summer p co 2 values and low winter values at both sites large large amplitude high frequency variations superimposed on this seasonal cycle reflect cave air circulation here we model stalagmite growth rates which are controlled partly by co 2 degassing rates from drip water by considering both the seasonal and high frequency cave air p co 2 variations modeled hourly growth rates for stalagmite cc bil from crag cave in sw ireland reach maxima in late december 0 063 m h 1 and minima in late june early july 0 033 m h 1 for well mixed diffuse flow cave drips such as those that feed cc bil high summer cave air p co 2 depresses summer calcite deposition while low winter p co 2 promotes degassing and enhances deposition rates in stalagmites fed by well mixed drips lacking seasonal variations in 18 o integrated annual stalagmite calcite 18 o is unaffected however seasonality in cave air p co 2 may influence non conservative geochemical climate proxies e g 13 c sr ca stalagmites fed by seasonal drips whose hydrochemical properties vary in response to seasonality may have higher growth rates in summer because soil air p co 2 may increase relative to cave air p co 2 due to higher soil temperatures this in turn may bias stalagmite calcite 18 o records towards isotopically heavier summer drip water 18 o values resulting in elevated calcite 18 o values compared to the equilibrium values predicted by calcite water isotope fractionation equations interpretations of stalagmite based paleoclimate proxies should therefore consider the consequences of cave air p co 2 variability and the resulting intra annual variability in calcite deposition rates

comparison of high resolution sub annual records of trace elements in a modern 1911 1992 speleothem with instrumental climate data from southwest australia high spatial resolution measurements of mg p u sr ba and na using 193 nm excimer laser ablation inductively coupled plasma mass spectrometry has revealed clearly resolvable annual cycles in a modern speleothem from southwestern australia the age of this stalagmite is established by the dates of emplacement and removal of the boardwalk where it grew 1911 1992 this chronological constraint allows for the first confident comparison between the instrumental climate record and speleothem trace element content eleven laser ablation transects across a 0 5 mm wide section of the speleothem growth axis were measured cycles that could be matched between adjacent transects were stacked into a master record to minimise variability between tracks and permit greater confidence in comparing the trace elements to the instrumental climate record p and u positively and mg inversely mimic the sudden 20 decrease in annual rainfall experienced by this region since 1965 we argue that p from seasonal vegetation decay is transported to the speleothem before it is mineralised in the soil owing to the low p retention capacity of southwest australian soils both vegetation activity and the transport of vegetation derived hpo42 are sensitive to rainfall groundwater p concentration may also influence the transport of u through the strong affinity between phosphate and uranyl ions mg appears to be sensitive to groundwater residence time as this affects drip water mg ca composition by preferential loss of ca during drier episodes when calcite precipitates before reaching the stalagmite the effects of groundwater residence time may also be important for sr on inter annual scales however the behaviour of sr on the annual cycle is opposite to mg but compatible with ba and na which are shown to depend on speleothem growth rate

cordierite gedrite rocks from the central metasedimentary belt boundary thrust zone grenville province ontario mesoproterozoic metavolcanic rocks with affinities to the composite arc belt cordierite gedrite rocks in the southern grenville province occur near the base of the central metasedimentary belt boundary thrust zone interpreted by some as a crustal suture between the 1 29 1 24 ga composite arc belt and 1 4 ga rocks of laurentia major and trace element compositions of these rocks are consistent with volcanic protoliths that range in composition from basalt to dacite these cordierite gedrite rocks have low cao average 1 2 wt and major element and oxygen isotope ratios suggestive of hydrothermal alteration before metamorphism rare earth element ree compositions also indicate igneous protoliths although some ree patterns have been modified by local melt extraction the trace element compositions of cordierite gedrite rocks and neodymium isotope systematics are similar to those of metavolcanic rocks in the composite arc belt and are consistent with the extension of the composite arc belt to the base of the boundary thrust zone

cave air ventilation and co2 outgassing by radon 222 modeling how fast do caves breathe abstract in general the rate and timing of calcite precipitation is in part affected by variations in cave air co2 concentrations knowledge of cave ventilation processes is required to quantify the effect variations in co2 concentrations have on speleothem deposition rates and thus paleoclimate records in this study we use radon 222 222rn as a proxy of ventilation to estimate co2 outgassing from the cave to the atmosphere which can be used to infer relative speleothem deposition rates hollow ridge cave a wild cave preserve in marianna florida is instrumented inside and out with multiple micro meteorological sensor stations that record continuous physical and air chemistry time series data our time series datasets indicate diurnal and seasonal variations in cave air 222rn and co2 concentrations punctuated by events that provide clues to ventilation and drip water degassing mechanisms average cave air 222rn and co2 concentrations vary seasonally between winter 222rn 50 dpm l 1 where 1 dpm l 1 60 bq m 3 co2 360 ppmv and summer 222rn 1400 dpm l 1 co2 3900 ppmv large amplitude diurnal variations are observed during late summer and autumn 222rn 6 to 581 dpm l 1 co2 360 to 2500 ppmv we employ a simple first order 222rn mass balance model to estimate cave air exchange rates with the outside atmosphere ventilation occurs via density driven flow and by winds across the entrances which create a venturi effect the most rapid ventilation occurs 25 m inside the cave near the entrance 45 h 1 1 33 min turnover time farther inside 175 m exchange is slower and maximum ventilation rates are 3 h 1 22 min turnover time we estimate net co2 flux from the epikarst to the cave atmosphere using a co2 mass balance model tuned with the 222rn model net co2 flux from the epikarst is highest in summer 72 mmol m 2 day 1 and lowest in late autumn and winter 12 mmol m 2 day 1 modeled ventilation and net co2 fluxes are used to estimate net co2 outgassing from the cave to the atmosphere average net co2 outgassing is positive net loss from the cave and is highest in late summer and early autumn about 4 mol h 1 and lowest in winter about 0 5 mol h 1 modeling of ventilation net co2 flux from the epikarst and co2 outgassing to the atmosphere from cave monitoring time series can help better constrain paleoclimatic interpretations of speleothem geochemical records

inverting airborne geophysical data for mega cell and giga cell 3d earth models today s mineral exploration is driven by the simple fact that discovery rates have not kept pace with the depletion of existing reserves to improve discovery rates there is an industry wide consensus on the need to increase the discovery space by exploring under cover and to greater depths this attracts increased risks which may be mitigated by improved targeting to do this mining geophysics needs to shift toward 3d geological models founded upon improved petrophysical understanding and geophysical inversion regardless of the inversion methodology used all geological constraints manifest themselves in the user s prejudice of an a priori model upper and lower bounds and choice of regularization however the practice of geologically constrained inversion is not the major problem needing to be addressed it is known and accepted that geology is inherently 3d and is a result of complex overlapping processes related to genesis metamorphism deformation alteration and or weathering yet the mining geophysics community to date has not fully accepted that geophysics should also be 3d and most often relies on qualitative analysis 1d inversion and depositscale 2d or 3d inversion there are many reasons for this unfortunate deficiency not the least of which has been the lack of capacity of existing 3d inversion algorithms to date these have not been able to invert entire surveys with sufficient resolution in sufficient time to practically affect exploration decisions this problem is most critical for airborne geophysical sur

diurnal to interannual rainfall δ 18 o variations in northern borneo driven by regional hydrology the relationship between climate variability and rainfall oxygen isotopic 18o variability is poorly constrained especially in the tropics where many key paleoclimate records rely on past rainfall isotopes as proxies for hydroclimate here we present a daily resolved 5 yr long timeseries of rainfall 18o from gunung mulu national park located in northern borneo 4 n 114 e in the heart of the west pacific warm pool and compare it to local and regional climatic variables daily rainfall 18o values range from 0 7 to 18 5 and exhibit a weak but significant inverse relationship with daily local precipitation amount r 0 19 p 0 05 consistent with the tropical amount effect day to day 18o variability at mulu is best correlated to regional precipitation amount averaged over the preceding week r 0 64 p 0 01 the inverse relationship between mulu rainfall 18o and local regional precipitation amount increases with increased temporal averaging reaching r 0 56 r 0 72 on monthly timescales large negative multi day rainfall 18o anomalies of up to 16 occur every 30 90 days and are closely associated with wet phases of the intraseasonal madden julian oscillation a weak semi annual seasonal cycle in rainfall 18o of 2 3 bears little resemblance to seasonal precipitation variability pointing to a complex sequence of moisture sources and or trajectories over the course of the year interannual rainfall 18o variations of 6 8 are significantly correlated with indices of the el nino southern oscillation with increased rainfall 18o during relatively dry el nino conditions and vice versa during la nina events we find that mulu rainfall 18o outperforms mulu precipitation amount as a tracer of basin scale climate variability highlighting the time and space integrative nature of rainfall 18o taken together our results suggest that rainfall 18o variability at mulu is significantly influenced by the strength of regional convective activity as such our study provides further empirical support for the interpretation of 18o based paleo reconstructions from northern borneo stalagmites as robust indicators of regional scale hydroclimate variability where higher 18o reflects regional drying

petrogenetic evolution of felsic volcanic sequences associated with phanerozoic volcanic hosted massive sulphide systems the role of extensional geodynamics abstract felsic volcanic hosted massive sulphide deposits form in many different geotectonic environments usually associated with episodes of extension however empirical geochemical links between felsic volcanism geotectonic environment and extensional geodynamics have not been adequately documented so as to distill the fundamental relationships between these features and formation of volcanic hosted massive sulphide vhms mineralization which is important considering most vhms deposits are hosted in felsic volcanic bearing sequences using felsic geochemical data from six different vhms mineralized phanerozoic geotectonic settings it seems that the felsic geochemical data are consistent with the overall geotectonic interpretations for these areas which in turn helps in stratigraphic and geotectonic interpretations for detailed vhms exploration in extensional geodynamic settings bimodal volcanism is common compared to the continuum of compositions observed under compressional to neutral high stress regimes in calc alkaline arc building environments the empirical geochemical metallogenic vhms relationships evident in the archean felsic volcanic rocks in particular the low zr y n yb n 2 o conditions in different source areas and geotectonic environments they seem to be the predominant controls on the compositional evolution of felsic magmas in extensional settings because of the limited degree of assimilation and fractional crystallization afc affecting their compositions with rapid intrusion into the uppermost crust to positions were they achieve neutral buoyancy in the volcanic to subvolcanic environment within plate felsic or a type anorogenic type and anomalous ocean ridge or type felsic magmas that have tholeiitic affinities relatively low alkali elements are common within parts of the volcanic sequences hosting massive sulphide deposits reflecting in part a relationship to extension the high contents of high field strength elements zr ga lree hree y nb etc and other lines of evidence indicate they are relatively high temperature relatively reduced magmas probably derived from previously dehydrated granulitic or melted oceanic simatic or continental sialic crust low p granulites or amphibolites but also in some cases possibly mantle rocks such that they are significantly water undersaturated during melting i e a h 2 o 1 reduced viscosities typical of high temperature melts enable rapid intrusion to higher levels diking vs diapirism higher rates of heat advection from mantle mafic magmas into the thickened oceanic and or continental crust during lithospheric extension are needed to facilitate melting of these rock to form a type and or or type partial melts tholeiitic felsic this usually results in bimodal magmatism as magma mixing is not favored in extensional settings especially at high magma production intrusion and extrusion rates i e high heat flow this would inhibit ferromagnesian phase in particular hornblende and magnetite fractionation especially at low f o 2 in the felsic magmas that would deplete the melt in y hree as well as ore related elements particularly zn which is 2 to 3 times higher in a type and or type rocks compared to other magma types therefore the empirical felsic igneous geochemical metallogenic relationships observed by others low zr y n yb n

calcrete and coal in late carboniferous cyclothems of nova scotia canada climate and sea level changes linked modern tropical peats require continuity of precipitation for accumulation whereas calcretes and calcic vertisols require strongly seasonal conditions the 20 30 m thick cyclothems of the sydney basin nova scotia canada show a systematic alternation of coals and other hydromorphic paleosols with calcretes and calcic vertisols this implies strong variation in seasonality during the duration of a cyclothem estimated at 200 ka in at least one cyclothem calcic paleosols formed on an interfluve adjacent to a paleovalley cut through marine strata suggesting that a more seasonal and probably drier climate prevailed during sea level lowstand the calcic paleosols are estimated to have formed during periods of 10 sup 4 yr possibly indicative of partial control by obliquity and precessional cycles 27 refs 5 figs 1 tab

the source of pedogenic carbonate associated with gold calcrete anomalies in the western gawler craton south australia abstract elevated au concentrations above bedrock mineralization are commonly closely associated with calcrete in arid residual and semi residual soils in australia the origin of australian calcrete has been argued for many years but there have been very few published studies calcrete from au deposits and prospects and elsewhere in the gawler craton south australia were studied for their geochemical composition and sr and c isotope ratios by comparing carbonate 87 sr 86 sr ratios with underlying weathered rock and bedrock it is demonstrated that many samples have overwhelmingly atmospheric sr 94 and by inference ca 98 rather than a local bedrock or soil mineral origin the isotopic composition of calcretes at the challenger gold deposit lie on a mixing trend of decreasingly marine sr from the nullarbor plain to tarcoola 300 km to the east the 13 c pdb values 7 5 to 0 1 suggest that the carbonate c in calcrete has a mixed origin derived from c3 and c4 plants a model is presented to explain how the au ca association may form in calcrete at challenger based on these new sr and c isotope data and in which the role of plants and atmospherically deposited sr and ca combine with pre existing au in the soil the implication for mineral exploration is that since most of the ca is derived from marine sources it is not a pre requisite that autochthonous soil minerals derived from underlying weathered bedrock supply ca for calcrete to form and for the au ca association to occur thus the independence of the ca with respect to underlying lithology reaffirms the usefulness of calcrete as a sampling medium for au exploration

geochemistry and architecture of the host sequence of the massive sulfides in the northern iberian pyrite belt abstract the northernmost iberian pyrite belt hosts several small felsic volcanogenic massive sulfide orebodies geochemically the volcanic sedimentary complex is dominated by andesitic to rhyolitic calc alkaline magmatic rocks with a significant proportion of dacite and andesite the lower felsic and upper felsic units are geochemically identical and probably represent dismembered parts of a single volcanic felsic complex if that holds true massive sulfide deposits of the northern ipb are hosted by volcaniclastic rocks located in the hanging wall of a single unit dominated by dacite rhyolite dome complexes this volcanic unit is characterized by zr contents structural analysis and the geochemistry suggest that the volcanic sequence is tectonically imbricated with the youngest units located at the lowest structural position the proposed reconstructed stratigraphic sequence comprises an andesitic footwall overlain by the felsic complexes of the middle felsic and lower upper felsic units thus the massive sulfide deposits formed toward the top of the whole sequence and associated with the youngest felsic rocks having a specific geochemistry

low temperature alteration at the world class laronde penna archean au rich volcanogenic massive sulfide deposit abitibi subprovince quebec canada evidence from whole rock oxygen isotopes the oxygen isotope composition of 169 whole rock samples from the world class laronde penna au rich volcanogenic massive sulfide deposit range from 6 5 to 22 0 fractional crystallization from basalt to rhyolite accounts for a variation of approximately 2 in primary whole rock 18o values the remaining variance in whole rock 18o values found at laronde penna must therefore be ascribed to water rock exchange with hydrothermal fluids the metamorphosed hydrothermally altered host rocks have been subdivided according to mineralogical assemblages which display weak covariance with 18o values and whole rock geochemical alteration indices water rock equilibrium exchange models indicate that the high 18o values that characterize the laronde penna deposit are compatible with low temperature 150oc hydrothermal alteration at high water rock oxygen atomic ratios 1 50 zones of lower 18o values stratigraphically beneath the principal ore lens 20 north indicate local zones of higher temperature hydrothermal alteration the oxygen isotope composition of the hydrothermal fluid is estimated to have been 5 as a consequence of mixing between seawater 18o 0 and a component of magmatic water degassed from the volcanic and intrusive rocks associated with the laronde penna deposit

partitioning of mg sr ba and u into a subaqueous calcite speleothem abstract the trace element geochemistry of speleothems is becoming increasingly used for reconstructing palaeoclimate with a particular emphasis on elements whose concentrations vary according to hydrological conditions at the cave site e g mg sr ba and u an important step in interpreting trace element abundances is understanding the underlying processes of their incorporation this includes quantifying the fractionation between the solution and speleothem carbonate via partition coefficients where the partitioning d of element x dx is the molar ratio x ca in the calcite divided by the molar ratio x ca in the parent water and evaluating the degree of spatial variability across time constant speleothem layers previous studies of how these elements are incorporated into speleothems have focused primarily on stalagmites and their source waters in natural cave settings or have used synthetic solutions under cave analogue laboratory conditions to produce similar dripstones however dripstones are not the only speleothem types capable of yielding useful palaeoclimate information in this study we investigate the incorporation of mg sr ba and u into a subaqueous calcite speleothem cd3 growing in a natural cave pool in italy pool water measurements extending back 15 years reveal a remarkably stable geochemical environment owing to the deep cave setting enabling the calculation of precise solution x ca we determine the trace element variability of modern subaqueous calcite from a drill core taken through cd3 to derive dmg dsr dba and du then compare these with published cave cave analogue and seawater analogue studies the dmg for cd3 is anomalously high 0 042 0 002 compared to previous estimates at similar temperatures 8 c the dsr 0 100 0 007 is similar to previously reported values but data from this study as well as those from tremaine and froelich 2013 and day and henderson 2013 suggest that na sr might play an important role in sr incorporation through the potential for na to outcompete sr for calcite non lattice sites dba in cd3 0 086 0 008 is similar to values derived by day and henderson 2013 under cave analogue conditions whilst du 0 013 0 002 is almost an order of magnitude lower possibly due to the unusually slow speleothem growth rates

rainfall recharge relationships within a karstic terrain in the eastern mediterranean semi arid region israel δ 18o and δd characteristics annual rainfall variations and processes in the upper vadose zone exert a profound influence on the chemical and isotopic compositions of waters of carbonate aquifers in semi arid climatic zones in order to define these processes we have studied the surface temperatures during rainfall events the isotopic composition of rain infiltrating and groundwaters this study was carried out within a karstic terrain soreq cave israel located in cenomanian dolomitic rocks approximately 40 km inland of the mediterranean sea and 400 m above sea level the climate is typical of the eastern mediterranean semi arid conditions with a rainy winter and dry summer and the average annual rainfall in the area is 500 mm close monitoring indicates that the d and 18o values of individual rainstorm events decrease with increasing rainfall annual average isotopic values of years with rainfall of 500 600 mm do not vary systematically years with extreme rainfall values define a negative covariation between the 18o and rainfall the d 18o relationship of all rain events of more than 20 mm fall on the mediterranean meteoric water line mmwl with a slope of 8 and d excesses of 20 30 these rain events occur when mid winter surface temperatures are 5 to 10 c rainfall events of less than 20 mm mainly occurring at above 10 c have slopes of less than 8 and smaller d excess as a consequence of evaporation processes beneath the clouds two main water types infiltrating into the cave are recognized slow and fast drip slow drip occurs from the tips of stalactites and takes place throughout the year these waters represent seepage water that remains in the upper vadose zone for up to several decades fast drip emanates from fissures in the cave roof during the winter seasons these waters represent vadose flow with a short residence time of less than 1 year the infiltration of the fast drip water into the cave depends on the fracture system of the rock cover and on the intensity of the rainstorms in the inner parts of the cave where the rock cover is thick fast drip starts only after several massive 20 mm rainstorms whereas below a thin roof the response time of fast drip is a few hours to a few days after intensive rainstorms both fast and slow drip water fall on the mmwl indicating that they are derived mainly from the relatively intensive rainstorms that compose about 23 of the annual rainfall although fast dri water represents massive rainstorms their 18o and d values are nonetheless higher by 1 and 10 respectively relative to the average rainwater compisition this indicates that the fast drip water consists predominantly of water derived from intensive rainstorms admixed with a minor component of isotopically 18o and d enriched water which is represented by the slow drip waters the fast drip waters are derived mainly from massive rain events at surface temperatures of 5 to 10 c which thermally equilibrate with the host rock and upon reaching the cave they have already acquired the mean temperature 20 c of the cave

seasonal wetland carbonate sequences and dynamic catenas a re appraisal of palustrine limestones abstract palustrine carbonate cyclothems are compared directly to well documented peritidal carbonate cyclothems in the case of the latter the trend of increasing degree of exposure seen vertically through a cyclothem has been interpreted as due to the aggradation of the sediment surface relative to the semi diurnal tidal regime palustrine cyclothems also show similar increases in the degree of exposure and this is interpreted as the effect of sediment aggradation in a seasonal wetland regime the resulting changes in the drainage characteristic revealed in a palustrinc cyclothem reflect a type of seasonally variable catenary relationship referred to here as a dynamic catena this model explains the key features of palustrine cyclothems and suggests the importance of seasonal wetland environments in ancient continental settings

trace fossils and their palaeoecological significance in lower cretaceous lacustrine conservation deposits el montsec spain abstract la pedrera and la cabrua at el montsec spain are two lower cretaceous lacustrine conservation deposits konservat lagerstatten that have provided a rich diverse and well preserved faunal and floral fossil record although the lithographic limestones where the body fossils are found are finely laminated and essentially undisturbed by bioturbation epigenic trace fossils occur on the surface of certain laminae trace fossils at la pedrera include the fish trail undichna britannica and the arthropod trackway hamipes didactylus while the ichnospecies found at la cabrua are steinsfjordichnus brutoni gordia arcuata cochlichnus anguineus and undichna britannica all but the last corresponding to the activity of small invertebrates the trace fossil occurrences record short term events in a lake bottom that did not support any benthic life for most of its history differences in the trace fossil assemblages for the two localities agree with sedimentological data in attributing a more distal position for la pedrera

geology alteration and lithogeochemistry of the hood volcanogenic massive sulfide vms deposits nunavut canada the hood volcanogenic massive sulfide vms deposits are hosted by the 2 68 ga amooga booga volcanic belt abvb in the northwestern archaen slave craton and consist of three deposits hood 10 41 and 41a and three occurrences 46 461 and 462 the mineralized zones consist of massive to semi massive pyrrhotite pyrite chalcopyrite sphalerite and galena hosted predominantly by felsic volcanic flows within the predominantly mafic abvb the mineralized lenses occur at different stratigraphic levels and have textural alteration and stratigraphic features consistent with formation via subseafloor replacement the felsic volcanic rocks in the hood deposits can be subdivided into groups based on immobile trace element geochemistry the main felsic types a and b are petrographically indistinguishable type a has higher high field strength element hsfe and rare earth element ree contents than type b suggesting a higher temperature of formation type a rocks also have higher nb ta values indicative of a greater mantle input in their genesis compared to type b rocks mineralization is more closely associated with type a than type b rocks the two mafic volcanic rock types previously identified in the abvb type i and type ii both occur within the hood deposits the type ii mafic group is interpreted to be the result of variable crustal contamination of type i magma the volcanic rocks of the abvb are interpreted to have formed in a continental margin arc back arc setting the genesis of these magmatic suites involved magmatic underplating and emplacement through pre existing sialic basement that resulted in crustal melting mantle crust mixing and contamination leading to the aforementioned geochemical features in both mafic and felsic suites this type of extensional tectonic environment was likely associated with high heat flow and is similar to global vms environments proximal to extending continental margins e g sturgeon lake bathurst and finlayson lake the similarities of the abvb to other slave craton greenstone belts further highlights the overall potential for greenstone hosted vms mineralization in the slave craton chlorite sericite quartz is the dominant hydrothermal alteration assemblage in the hood deposits and is typical of vms style mineralization mass change calculations illustrate that elemental changes are typical of vms environments with gains in fe2o3 mgo and base metals associated with chlorite alteration near mineralized zones k2o gains associated with sericite alteration and losses of na2o in both alteration types

fish and tetrapod trace fossils from the upper carboniferous of puertollano spain abstract well preserved fish and tetrapod trace fossils occur in carboniferous stephanian c beds at puertollano they represent the first evidence of vertebrate ichnites in the carboniferous of spain the fish swimming traces are assigned to undichna britannica and undichna unisulca the dimensions and morphological features of the traces indicate that orthacanthus xenacanthidae elasmobranchii a shark very common in the basin might have been the trace producer a morpho functional analysis of the traces suggests an axial undulatory anguilliform mode of locomotion of xenacanth sharks this conclusion is consistent with the eel like body found in all known xenacanthids tetrapod trackways referred to puertollanopus microdactylus ichnogen et ichnosp nov and resting traces are described both walking and resting tracks are assigned to a small terrestrial tetrapod dimensions and proportions of the tracks and size and morphology of the impressions of manus and pes suggest a microsaur amphibian or a small reptile as the track maker this represents the first evidence of these vertebrates in the basin the superposition of fish trails and tetrapod trackways strongly suggests tidal processes in a marginal marine depositional setting this interpretation agrees with recent sedimentological geochemical and palynological data from the puertollano basin

significance of pre 1860 ma granitoid magmatism for crustal evolution and exploration targeting in the flin flon assemblage trans hudson orogen canada granitoid plutonism a significant contributor to orogenic evolution is a commonly overlooked vector in exploration targeting using the flin flon glennie complex of the trans hudson orogen as a template we show that the geochemistry of granitoid rocks can be a useful parameter in differentiating prospective and nonprospective areas for volcanic hosted massive sulfide vhms deposits the flin flon glennie complex includes 1910 to 1860 ma plutonic rocks that can be subdivided into three suites 1 juvenile arc related rocks of ferroan and magnesian subtypes 2 contaminated arc related rocks and 3 successor arc related rocks of both low and high sr y ratio petrogenesis of ferroan juvenile and low sr y successor arc plutons indicates they formed in regions of thinner crust and hence would have been associated with higher heat flow and arc rifting conditions that favor vhms endowment regions of the orogen with both ferroan and low sr y plutonic subtypes were long lived zones of thin crust and preserve vhms mineralization related to both juvenile and successor arc magmatism in contrast volcanic belts dominated by contaminated arc or high sr y successor arc plutons formed on thicker substrates with contaminated arc rocks built on archean paleoproterozoic pericratonic slivers and high sr y successor arc rocks associated with submarine to subaerial arc systems these regions of thicker crust demonstrably lack vhms deposits and were also the locus for late unroofing our results suggest that pluton geochemistry regionally correlates with mineral occurrence and could represent a useful regional exploration tool in buried or poorly exposed parts of the flin flon glennie complex and other paleoproterozoic orogens

carbon transfer dynamics from bomb 14c and δ13c time series of a laminated stalagmite from sw france modelling and comparison with other stalagmite records twenty two ams 14c measurements have been made on a modern stalagmite from sw france in order to reconstruct the 14c activity history of the calcite deposit annual growth laminae provides a chronology up to 1919 a d results show that the stalagmite 14c activity time series is sensitive to modern atmosphere 14c activity changes such as those produced by the nuclear weapon tests the comparison between the two 14c time series shows that the stalagmite time series is damped its amplitude variation between pre bomb and post bomb values is 75 less and the time delay between the two time series peaks is 16 years 3 a model is developed using atmosphere 14c and 13c data fractionation processes and three soil organic matter components whose mean turnover rates are different the linear correlation coefficient between modeled and measured activities is 0 99 these results combined with two other stalagmite 14c time series already published and compared with local vegetation and climate demonstrate that most of the carbon transfer dynamics are controlled in the soil by soil organic matter degradation rates where vegetation produces debris whose degradation is slow the fraction of old carbon injected in the system increases the observed 14c time series is much more damped and lag time longer than that observed under grassland sites the same mixing model applied on the 13c shows a good agreement r2 0 78 between modeled and measured stalagmite 13c and demonstrates that the suess effect due to fossil fuel combustion in the atmosphere is recorded in the stalagmite but with a damped effect due to som degradation rate the different sources of dead carbon in the seepage water are calculated and discussed

a tidal origin for coarsening upward sequences above two wilcox lignites in east texas conventional palaeogeographic reconstructions show a large river system occupying the east texas embayment during the deposition of the wilcox group coarsening upward sequences above wilcox lignites in east texas have been interpreted as floodplain splays however the bedding types sedimentary structures and shallow scour surfaces in a coarsening upward sequence above the main seam at the martin lake mine in panola county indicate deposition in water stirred by tidal and wave activity the bedding types include sand streaks in mud and lenticular wavy and flaser bedding the sedimentary structures include abundant wave ripple lamination and large scale crossbeds with thin closely spaced mud drapes these crossbeds suggest traction currents of short duration alternating with periods of slack water pollen from broadleaf hardwood trees is the most common element of the palynoflora from the coarsening upward sequence at the mine the upper reaches of riverine estuaries along the se coast of the united states provide a modern analogue for the environment of deposition of the wilcox sediments at the martin lake mine here tidal currents extend inland to places where freshwater aquatic plants and forests border the estuaries the same bedding types and sedimentary structures that occur in the sediments at the martin lake mine occur in a coarsening upward sequence above a lignite at the big brown mine in freestone county recognition of the tidal origin of the coarsening upward sequences suggests an embayed coast or a shoreline within the east texas embayment during the deposition of the strata above the lignites

global comparisons of volcanic associated massive sulphide districts although volcanic associated massive sulphide vms deposits have been studied extensively the geodynamic processes that control their genesis location and timing remain poorly understood compar

petrochemistry hydrothermal alteration mineralogy and sulfur isotope geochemistry of the turgeon cu zn volcanogenic massive sulfide deposit northern new brunswick canada the turgeon deposit is a mafic type cu zn volcanogenic massive sulfide vms deposit it is hosted by middle ordovician pillow basalts of the devereaux formation of the fournier group within the elmtree belledune inlier near the bathurst mining camp bmc in northern new brunswick canada the turgeon deposit consists of two cu zn massive sulfide lenses 100m zn 48 49 composed of pyrite chalcopyrite pyrrhotite and sphalerite which are underlain by chalcopyrite pyrite stockwork veins pyrite is overprinted and replaced by chalcopyrite in the stockwork and vent complex sulfide facies where both minerals are enriched in se and co relative to pyrite and chalcopyrite in the massive pyrite and breccia sulfide facies in se and co display a positive covariation with cu whereas zn displays a positive covariation with cd trace element geochemistry indicates that the host rocks are primarily tholeiitic basalts and andesites that have signatures between that of mid ocean ridge basalt and island arc

centennial scale holocene climate variability revealed by a high resolution speleothem δ18o record from sw ireland evaluating the significance of holocene submillennial 18 o variability in the greenland ice cores is crucial for understanding how natural climate oscillations may modulate future anthropogenic warming a high resolution oxygen isotope record from a speleothem in southwestern ireland provides evidence for centennial scale 18 o variations that correlate with subtle 18 o changes in the greenland ice cores indicating regionally coherent variability in the early holocene evidence for previously undetected early holocene cooling events is presented but mid to late holocene ice rafting in the north atlantic appears to have had little impact on 18 o at this ocean margin site

an isotopic and modelling study of flow paths and storage in quaternary calcarenite sw australia implications for speleothem paleoclimate records abstract we investigated the distinctive shallow sub surface hydrology of the southwest western australia swwa dune calcarenite using observed rainfall and rainfall 18 o soil moisture cave drip rate and dripwater 18 o over a six year period august 2005 march 2012 a lumped parameter hydrological model is developed to describe water fluxes and drip 18 o comparison of observed data and model output allow us to assess the critical non climatic karst hydrological processes that modify the precipitation 18 o signal and discuss the implications for speleothem paleoclimate records from this cave and those with a similar karst setting our findings include evidence of multiple reservoirs characterised by distinct 18 o values and recharge responses low and high flow sites dripwaters exhibit 18 o variations in wet versus dry years at low flow sites receiving diffuse seepage from the epikarst with an attenuated isotopic composition that approximates mean rainfall recharge from high magnitude rain events is stored in a secondary reservoir which is associated with high flow dripwater that is 1 lower than our monitored low flow sites 18 o one drip site is characterised by mixed flow behaviour and exhibits a non linear threshold response after the cessation of drainage from a secondary reservoir following a record dry year 2006 additionally our results yield a better understanding of the vadose zone hydrology and dripwater characteristics in quaternary age dune limestones we show that flow to our monitored sites is dominated by diffuse flow with inferred transit times of less than one year diffuse flow appears to follow vertical preferential paths through the limestone reflecting differences in permeability and deep recharge into the host rock

neodymium isotope geochemistry of felsic volcanic and intrusive rocks from the yukon tanana terrane in the finlayson lake region yukon canada devonian mississippian felsic rocks from the finlayson lake region have variable geochemical and nd isotopic characteristics that provide insights into the tectonic and metallogenic evolution of the yukon tanana terrane ytt and the northern cordillera late devonian 365 360 ma calc alkaline and tholeiitic arc felsic rocks in the mafic dominated fire lake unit yield end350 4 8 and 0 1 respectively and have 1 49 1 94 ga depleted mantle model ages tdm devonian mississippian 360 356 ma felsic volcanic kudz ze kayah unit wolverine succession and intrusive rocks grass lakes suite associated with volcanogenic massive sulphide vms deposits have end350 7 8 to 9 5 with tdm 1 59 2 25 ga a granitoid sample from the early mississippian 350 345 ma simpson range plutonic suite has end350 12 9 and tdm 2 01 ga similar to previously reported values for this suite the vms associated grass lakes suite of granitoids has higher high field strength element hfse and rare earth element ree contents and higher zr sc zr tio2 nb la and zr la values relative to the simpson range plutonic suite these geochemical features are similar to coeval vms associated felsic volcanic rocks in the kudz ze kayah unit the identification of similar hfse ree enriched felsic volcanic and subvolcanic intrusive rocks may aid in delineating prospective regions for vms mineralization in the ytt and other continental margin arc to back arc environments the geochemical and nd isotopic data for these ytt felsic rocks suggest that they reflect episodic mid paleozoic arc fire lake unit simpson range plutonic suite and back arc magmatism kudz ze kudz unit wolverine succession built upon a transitional basement with variable but significant influence from evolved proterozoic crustal materials

a high resolution absolute dated late pleistocene monsoon record from hulu cave china oxygen isotope records of five stalagmites from hulu cave near nanjing bear a remarkable resemblance to oxygen isotope records from greenland ice cores suggesting that east asian monsoon intensity changed in concert with greenland temperature between 11 000 and 75 000 years before the present yr b p between 11 000 and 30 000 yr b p the timing of changes in the monsoon as established with 230th dates generally agrees with the timing of temperature changes from the greenland ice sheet project two gisp2 core which supports gisp2 s chronology in this interval our record links north atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer east asian monsoon originates

the eastern mediterranean paleoclimate as a reflection of regional events soreq cave israel the climate of the eastern mediterranean region of the last 60 ky was determined by a high resolution study of the oxygen and carbon isotopic composition 1500 measurement pairs of speleothems from the soreq cave israel with chronology provided by 53 precise 230 th 234 u tims ages the high precision of the speleothem tims ages permits us to determine the timing of regional climatic events in the eastern mediterranean region and to see if they correlate with global events during the period from 60 to 17 ky the 18 o and 13 c values were generally 2 2 5 higher than during the period from 17 ky to present this is consistent with the climatic transition from glacial to interglacial within the 60 to 17 ky period the soreq cave stable isotope profile includes four cold peaks at 46 35 25 and 19 ky and 2 warm peaks at 54 and 36 ky in addition the period 17 ky has two more cold peaks at 16 5 and from 13 2 to 11 4 ky the ages of four of the six cold peaks correlate well with the ages of three heinrich events h1 h2 h5 and with the age of the younger dryas however the other two heinrich events are not reflected in the soreq cave record several other isotope peaks which appear during the last 7 ky are contemporaneous with regional climatic events in the middle east and north africa in addition to the drop in 18 o and 13 c observed between the last glacial and the holocene sharp simultaneous drops in 234 u 238 u 0 ratios sr concentrations and in 87 sr 86 sr are also observed suggesting that the latter are climate related these variations are interpreted in terms of major changes in the temperature the mean annual rainfall and its isotopic composition the isotopic composition of the mediterranean vapor source the soil moisture conditions and in the mixing proportions of sources with different 87 sr 86 sr ratios sea spray dust particles and dolomitic host rock

textural elemental and isotopic characteristics of pleistocene phreatic cave deposits jabal madar oman abstract two main types of karst formation are commonly known the surficial meteoric one and the subsurface hypogenic karst which can be related to both carbonic h2co3 and sulfuric h2s acids this paper documents evidence for a third co2 regime related type of karst that is less commonly described petrographic and geochemical properties of exhumed pleistocene phreatic cave deposits from the diapiric jabal madar dome in northern oman are documented and discussed in a process oriented context these calcites form at the interface between two fundamentally different diagenetic and hydrogeological domains the deep seated hydrothermal and the near surficial meteoric vadose one four calcite phases are recognized i acicular ii blocky to stubby elongated iii proto palisade and iv macro columnar calcites the macro columnar calcites forming the last stage of precipitation are conspicuous due to their cyclical red zonation and they form the main geochemical focus of this study fluid inclusion data point to fluid temperatures of between 30 to 50 c monophase liquid inclusions and elevated salinities 1 6 to 7 3 wt nacl equivalent low carbon isotope data 8 to 9 are in agreement with the influx of soil zone co2 whereas decreasing 18o 15 values might point to mixing of saline hydrothermal and 18o depleted meteoric freshwater i e two fluid sources trace element and stable isotope data shift between the different cement phases and vary cyclically across the red zoning in macro columnar calcites with respect to the intra crystal variability these patterns are perhaps best explained in the context of redox potential two interpretations are presented the one favored here suggests that the cyclical red zoning in macro columnar calcites is controlled by pleistocene monsoonal climate patterns

modelling of cyclic tidal rhythmites carboniferous of indiana and kansas precambrian of utah usa as a basis for reconstruction of intertidal positioning and palaeotidal regimes analyses are presented for a variety of ancient cyclic tidal rhythmites which exhibit well developed neap spring tidal periods many such rhythmites were formed within the upper intertidal zone and exhibit truncated cycles that contain relatively few discrete lamina per neap spring cycle in such cases it can be difficult to determine if the originated palaeotidal system was diurnal or semidiurnal based on sedimentological controls observed in modern analogues the development of cyclic tidal rhythmites can be modelled by use of predicted tidal height information the modelling used a 19 year long series of tidal heights which were subsequently used to approximate tidal velocities and rhythmite sedimentation modelling was based on a range of diurnal to semidiurnal regimes and comparisons were performed at a number of levels within the intertidal zone this modelling produced a long series of simulated laminae thickness series which could be cross correlated with ancient laminae thickness series measured directly from ancient rhythmites this approach involved 1 6 106 comparisons of each ancient rhythmite series to the series simulated from the predictive tidal height information the high correlations derived for such comparisons indicate that reasonable approximations to the palaeotidal systems can be made in some cases it is possible to determine the diurnal or semidiurnal nature of the originating palaeotidal system

terrestrial biota in coastal marine deposits fossil lagerstatten in the pennsylvanian of kansas usa abstract the fossil animal assemblages of three pennsylvanian marine lagerstatten of kansas are compared detailed taphonomic investigations and comparison of total fossil assemblages are the most reliable for palaeoenvironment interpretation functional morphology taxonomic uniformitarianism behavior absence of marine fossils for freshwater and palaeogeography are weak criteria of a hypothesis of freshwater depositional environment based on the assumption that closely related taxa have similar environment preferences functions and behaviors in general invertebrates being less mobile are better indicators of their general environment than vertebrates terrestrial vertebrates can dominate the fossil vertebrate assemblage of a clearly marine depositional palaeoenvironment as long as acceptable indicators of palaeozoic freshwater environment are not found the hypothesis of freshwater environment cannot stand the test only easily falsified by the discovery of marine fossils fishes may indicate marine connectedness not necessarily a marine depositional environment

the recovery and isotopic measurement of water from fluid inclusions in speleothems the isotopic composition of speleothems is a useful palaeoclimatic indicator but its value would be enhanced if information on the composition of the parent dripwaters could be recovered from fluid inclusions in the speleothem calcite to develop a robust method for extracting and measuring oxygen and hydrogen isotopic composition of fluid inclusions we have used anhydrous iceland spar and microlitre glass capillaries of water as an analogue system crushing the capillary and calcite together in a high vacuum cell we have investigated the adsorbtive and isotopic behaviour of water when exposed to clean fracture surfaces significant water adsorption occurs at room temperature accompanied by large negative isotopic shifts of both oxygen and hydrogen in the recovered foe water at h2o caco3 mass ratios c for 60 min totally desorbs the water and allows retrieval of the correct isotopic composition application of these methods to a british late holocene speleothem yields delta o 18 and delta h 2 compositions for the inclusion water which are closely comparable with the modern cave dripwaters and local precipitation the results show that isotopic compositions can be recovered from inclusion samples of l equivalent to approximately ig of calcite with precisions that are useful for palaeoclimatic research 0 4 for delta o 18 and 3 for delta h 2 greater precision than this will require replicate analysis for each speleothem growth increment copyright c 2001 elsevier science ltd

stalagmite from the austrian alps reveals dansgaard oeschger events during isotope stage 3 implications for the absolute chronology of greenland ice cores a mass spectrometric uranium series dated stalagmite from the central alps of austria provides unprecedented new insights into high altitude climate change during the peak of isotope stage 3 the stalagmite formed continuously between 57 and 46 kyr before present a series of hendy tests demonstrates that the outer parts of the sample show a progressive increase of both stable c and o isotope values no such covariant increase was detected within the axial zone this in conjunction with other observations suggests that the continuous stable oxygen isotope profile obtained from the axial zone of the stalagmite largely reflects the unaltered isotopic composition of the cave drip water the n 18 o record shows events of high n 18 o values that correlate remarkably with interstadials 15 a and b 14 and 12 identified in the greenland ice cores interstadial 15b started rapidly at 55 6 kyr and lasted v300 yr only interstadial 15a peaked 54 9 kyr ago and was even of shorter duration v100 yr and interstadial 14 commenced 54 2 kyr ago and lasted v3000 yr this stalagmite thus represents one of the first terrestrial archives outside the high latitudes which record precisely dated dansgaard oeschger d o events during isotope stage 3 provided that rapid d o warmings occurred synchronously in greenland and the european alps the new data provide an independent tool to improve the grip and gisp2 chronologies 2002 elsevier science b v all rights reserved

climatic and environmental controls on speleothem oxygen isotope values variations in speleothem oxygen isotope values d 18 o result from a complicated interplay of environmental controls and processes in the ocean atmosphere soil zone epikarst and cave system as such the controls on speleothem d 18 o values are extremely complex an understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem d 18 o as paleoclimate and paleoenvironmental proxies and is best complemented by study of site specific cave processes such as infiltration flow routing drip seasonality and saturation state and cave microclimate among others this review is a process based summary of the multiple controls on d 18 o in the atmosphere soil epikarst and speleothem calcite illustrated with case studies primary controls of d 18 o in the atmosphere include temperature and relative humidity through their role in the multiple isotope effects variability and modifications of water d 18 o values in the soil and epikarst zones are dominated by evaporation mixing and infiltration of source waters the isotopically effective recharge into a cave system consists of those waters that participate in precipitation of caco3 resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state recent modeling experimental and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid caco3 and have implications for the hendy test to assist interpretation of speleothem d 18 o time series quantitative and semi quantitative d 18 o climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records finally several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of d 18 o to reconstruct past climate

continuous early last glacial palaeoenvironmental record from a tasmanian speleothem based on stable isotope and minor element variations a columnar stalagmite from a limestone cave in the florentine valley tasmania has been dated by three 230th 234u age determinations continuous profiles of 170 18o and 13c values as well as magnesium and strontium concentrations are presented 18o values indicate temperatures lower than today with a gradual temperature decline in the basal part of the profile punctuated by two short cooling events and culminating in a double temperature minimum between 70 and 60 ka the profile shows marked similarities with the gisp ice core record from greenland which shows two short intense stadials centred on 74 and 70 ka preceding the last glacial temperature minimum they have been correlated with heinrich events in north atlantic marine cores which in turn have been attributed to periodic massive discharges of icebergs into the north atlantic the tasmanian speleothem record suggests that these events may also have affected climates in the southern hemisphere the 13c variations also appear to indicate periodic environmental change minor element variations were found to be significantly correlated with isotopic changes strontium concentrations show a bimodal distribution indicating control by a switching mechanism tentatively attributed to variations in calcitic dust supply to the ground surface above the site

gold in the brunswick no 12 volcanogenic massive sulfide deposit bathurst mining camp canada evidence from bulk ore analysis and laser ablation icp ms data on sulfide phases the 329 mt brunswick no 12 volcanogenic massive sulfide deposit total resource of 163 mt at 10 4 zn 4 2 pb 0 34 cu and 115 g t ag is hosted within a middle ordovician bimodal volcanic and sedimentary sequence massive sulfides are for the most part syngenetic and the bulk of the sulfide ore occurs as a zn pb rich banded sulfide facies that forms an intimate relationship with a laterally extensive algoma type iron formation and defines the brunswick horizon zone refining of stratiform sulfides is considered to have resulted in the development of a large replacement style cu rich basal sulfide facies which is generally confined between the banded sulfide facies and an underlying stringer sulfide zone complex polyphase deformation and associated lower to upper greenschist facies regional metamorphism is responsible for the present geometry of the deposit textural modification has resulted in a general increase in grain size through the development of pyrite and arsenopyrite porphyroblasts which tend to overprint primary mineral assemblages despite the heterogeneous ductile deformation primary features have locally been preserved such as fine grained colloform pyrite and base and precious metal zonation within the main zone base metal and trace element abundances in massive sulfides from the brunswick no 12 deposit indicate two distinct geochemical associations the basal sulfide facies characterized by a proximal high temperature hydrothermal signature cu co bi se contains generally low au contents averaging 0 39 ppm n 34 conversely au is enriched in the banded sulfide facies averaging 1 1 ppm au n 21 and is associated with an exhalative suite of elements zn pb as sb ag sn finely laminated sulfide lenses hosted by iron formation at the north end of the main zone are further enriched in au averaging 1 7 ppm n 41 and ranging up to 8 2 ppm laser ablation inductively coupled plasma mass spectrometry icp ms analyses of pyrite n 97 from the north end of the main zone average 2 6 ppm au and range from the detection limit 0 015 ppm to 21 ppm overall these analyses reveal a distinct au sb as ag hg mn association within pyrite grains gold is strongly enriched in large pseudo primary masses of pyrite that exhibit relict banding and fine grained cores smaller euhedral pyrite porphyroblasts and euhedral rims of metamorphic origin surrounding the pyrite masses contain much less au sb ag as and sn arsenopyrite occurring chiefly as late porphyroblasts contains less au averaging 1 0 ppm and ranging from the detection limit 0 027 ppm to 6 9 ppm depth profiles for single spot laser ablation icp ms analyses of pyrite and arsenopyrite display uniform values of au and an absence of discrete microscopic inclusions of au bearing minerals which is consistent with chemically bonded au in the sulfide structure the pervasive correlation of au with sn in the zn pb rich banded sulfide facies suggests similar hydrothermal behavior during the waxing stages of deposition on the seafloor under high temperature 350oc and moderate to low ph conditions au and sn in hydrothermal fluids would be transported as chlorocomplexes an abrupt decrease in temperature and ah2s accompanied by an increase in fo2 and ph during mixing with seawater would lead to the simultaneous destabilization of both au and sn chlorocomplexes the enrichment of au in fine grained laminated sulfides on the periphery of the deposit accompanied by sporadic occurrences of barite and fe poor sphalerite supports lower hydrothermal fluid temperatures analogous to white smoker activity on the flanks of a large volcanogenic massive sulfide system in lower temperature 350oc and mildly acidic hydrothermal fluids au would be transported by thiocomplexes which exhibit multifunctional retrograde prograde solubility and a capacity to mobilize au to the outer parts of the sulfide mound the sluggish nature of this low temperature venting together with larger variations in ambient fo2 could lead to a sharp enrichment of au towards the stratigraphic hanging wall of massive sulfide deposits

precise dating of dansgaard oeschger climate oscillations in western europe from stalagmite data the signature of dansgaard oeschger events millennial scale abrupt climate oscillations during the last glacial period is well established in ice cores and marine records but the effects of such events in continental settings are not as clear and their absolute chronology is uncertain beyond the limit of 14 c dating and annual layer counting for marine records and ice cores respectively here we present carbon and oxygen isotope records from a stalagmite collected in southwest france which have been precisely dated using 234u 230th ratios we find rapid climate oscillations coincident with the established dansgaard oeschger events between 83 000 and 32 000 years ago in both isotope records the oxygen isotope signature is similar to a record from soreq cave israel and deep sea records indicating the large spatial scale of the climate oscillations the signal in the carbon isotopes gives evidence of drastic and rapid vegetation changes in western europe an important site in human cultural evolution we also find evidence for a long phase of extremely cold climate in southwest france between 61 2 0 6 and 67 4 0 9 kyr ago

in situ measurement of seasonal δ18o variations and analysis of isotopic trends in a modern speleothem from southwest australia we present a record of seasonal and inter annual oxygen o and carbon c isotope ratios from an 81 year old stalagmite from moondyne cave southwest australia the growth history of stalagmite mnd s1 is known since it grew on a cave boardwalk that was installed in 1911 and removed in 1992 this stalagmite provides an excellent test of speleothem climate proxies because the regional climate is strongly seasonal wet winter dry summer and has experienced a 200 mm 20 reduction of mean rainfall since the mid 1960s and a 0 8 c temperature rise since 1953 seasonal variations in calcite o were measured in situ by high spatial resolution ion microprobe whilst inter annual variations of o and c were measured by conventional gas source mass spectrometry comparison of the speleothem stable isotopes and instrumental temperature records reveals that o variations are too large to be driven by temperature alone and are in the opposite sense however daily rainfall o measurements show that the mean seasonal range in o of rainfall in southwest australia is large 2 and inversely correlated with rainfall amount a rainfall driver for the speleothem o is confirmed by the detection of seasonal shifts of 0 7 1 5 in speleothem that track rainfall o smoothed by storage in the overlying limestone the seasonal range in speleothem o is larger than any inter annual and decadal variation observed in the record the prominent annual cycles in speleothem o revealed by ion microprobe analysis indicate that subtle changes in the frequency of intense winter rainfall events or possibly also moisture sources could produce significant changes in mean speleothem o the ion microprobe results also raise the possibility that the masses of speleothem calcite deposited in winter and summer could vary as a function of the seasonal drip rate and carbonate saturation state of these waters if this is the case then small changes in the relative masses of calcite deposited in winter and summer could produce significant shifts in mean o and c that have a complex relation to climate this finding should be generally applicable to the interpretation of long term trends in speleothem geochemical records for shallow cave sites where seasonal variations in geochemical tracers are relatively large including most of the sub tropical monsoon belts and mid to high latitudes with distinct rainfall seasons

precipitation rates and atmospheric heat transport during the cenomanian greenhouse warming in north america estimates from a stable isotope mass balance model stable isotope mass balance modeling results of meteoric 18o values from the cenomanian stage of the cretaceous western interior basin kwib suggest that precipitation and evaporation fluxes were greater than that of the present and significantly different from simulations of albian kwib paleohydrology sphaerosiderite meteoric 18o values have been compiled from the lower tuscaloosa formation of southwestern mississippi 25 n paleolatitude the dakota formation rose creek pit fairbury nebraska 35 n and the dunvegan formation of eastern british columbia 55 n paleolatitude these paleosol siderite 18o values define a paleolatitudinal gradient ranging from 4 2 vpdb at 25 n to 12 5 vpdb at 55 n this trend is significantly steeper and more depleted than a modern theoretical siderite gradient 25 n 1 7 65 n 5 6 vpdb and a holocene meteoric calcite trend 27 n 3 6 67 n 7 4 vpdb the cenomanian gradient is also comparatively steeper than the albian trend determined for the kwib in the mid to high latitudes the steep latitudinal trend in meteoric 18o values may be the result of increased precipitation and evaporation fluxes amount effects under a more vigorous greenhouse world hydrologic cycle a stable isotope mass balance model has been used to generate estimates of precipitation and evaporation fluxes and precipitation rates estimates of cenomanian precipitation rates based upon the mass balance modeling of the kwib range from 1400 mm yr at 25 n paleolatitude to 3600 mm yr at 45 n paleolatitude the precipitation evaporation p e flux values were used to delineate zones of moisture surplus and moisture deficit comparisons between cenomanian p e and modern theoretical siderite and holocene calcite latitudinal trends shows an amplification of low latitude moisture deficits between 5 25 n paleolatitude and moisture surpluses between 40 60 n paleolatitude the low latitude moisture deficits correlate with a mean annual average heat loss of 48 w m2 at 10 n paleolatitude present 8 w m2 at 15 n the increased precipitation flux and moisture surplus in the mid latitudes corresponds to a mean average annual heat gain of 180 w m2 at 50 n paleolatitude present 17 w m2 at 50 n the cenomanian low latitude moisture deficit is similar to that of the albian however the mid latitude 40 60 n precipitation flux values and precipitation rates are significantly higher albian 2200 mm yr at 45 n cenomanian 3600 mm yr at 45 n furthermore the heat transferred to the atmosphere via latent heat of condensation was approximately 10 6 that of the present at 50 n the intensified hydrologic cycle of the mid cretaceous greenhouse warming may have played a significant role in the poleward transfer of heat and more equable global conditions paleoclimatological reconstructions from multiple time periods during the mid cretaceous will aid in a better understanding of the dynamics of the hydrologic cycle and latent heat flux during greenhouse world conditions

oxygen and strontium isotopes from fossil shark teeth environmental and ecological implications for late palaeozoic european basins article i nfo fossil shark remains occur in both marine and nonmarine late palaeozoic deposits therefore their palaeo ecology is controversial the oxygen and strontium isotopic composition of biogenic fluorapatite in 179 teeth scales and spines predominantly of hybodontid lissodus and xenacanthiform orthacanthus xenacanthus bohemiacanthus triodus sharks from various late carboniferous moscovian to early permian artinskian basins of europe are used as ecological tracers to decipher diadromous or obligate freshwater lifestyle of the investigated taxa the 18 op values of the different shark teeth range from 11 7 to 20 2 within the different basins with mean values of 16 9 0 5 for the bohemian massif 16 2 0 8 for eastern germany 18 2 1 0 for southwestern germany 18 5 0 7 for southern central spain 17 6 0 4 for