filamentous microfossils in a 3 235 million year old volcanogenic massive sulphide deposit the record of archaean microfossils is sparse1 of the few bona fide fossil assemblages most are from shallow water settings and they are typically associated with laminated stromatolitic sedimentary rocks2 3 4 microfossils from deep sea hydrothermal systems have not been reported in precambrian rocks 544 million years old although thermophilic microbes are ubiquitous in modern sea floor hydrothermal settings5 6 and apparently have the most ancient lineages7 8 here i report the discovery of pyritic filaments the probable fossil remains of thread like microorganisms in a 3 235 million year old deep sea volcanogenic massive sulphide deposit from the pilbara craton of australia from their mode of occurrence the micro organisms were probably thermophilic chemotropic prokaryotes which inhabited sub sea floor hydrothermal environments they represent the first fossil evidence for microbial life in a precambrian submarine thermal spring system and extend the known range of submarine hydrothermal biota by more than 2 700 million years9 such environments may have hosted the first living systems on earth consistent with proposals for a thermophilic origin of life10 11 12 13

bikpela a large siliceous chimney from the pacmanus hydrothermal field manus basin papua new guinea the 2 7 m bikpela chimney differs from sulfide rich chimneys at pacmanus eastern manus basin by virtue of high silica content a stromatolite like layered structure and the presence of a large internal collapse cavity its interior is dominated by 5 to 10 mm thick primary laminae of opal a dominated fronds clouded by submicroscopic sphalerite inclusions set between thin subhorizontal growth borders larger sphalerites with sulfosalt galena intergrowths at frond ends project into discoid cavities under the growth borders a steeper second order lamination reflects arrested expansion of the 50 cm high internal collapse cavity underlying the cavity floor an axial breccia pipe contains distorted fragments of laminated interior modified by dissolution and then redeposition of opal and further growth of pyrite and sphalerite beneath a thin mn oxide crust a hard outer sphalerite barite carapace 5 cm thick and devoid of opal is banded parallel to the chimney exterior at least three stages of chimney growth are evident beginning with repetitive deposition of opaline frond layers probably developed from microbial mat precursors by overgrowth of hydrothermal opal and fine sphalerite next with rising fluid temperatures hydrothermal fe poor sphalerite with pb sulfosalts and galena deposited at frond ends and under growth borders and via lateral diffusion and mixing with seawater formed abundantly in the outer carapace of the chimney passage of hot more acid fluids into the chimney axial zone then caused dissolution of primary opal and consequent formation of the collapse cavity and underlying breccia pipe together with deposition of fe rich sphalerite and pyrite in second order fractures and cavities related to the collapse finally conductive cooling during or after this latter stage produced films and spherules of clear opal coating pores and grain margins throughout the structure apart from in the carapace bikpela contains significant gold and silver avg 8 7 ppm au 250 ppm ag n 9 but it is low overall in cu up to 0 5 wt in the pipe and pb up to 0 7 wt in the carapace its carapace is relatively rich in zn up to 54 wt ag as and sb with one sample containing 0 12 wt silver

submarine venting of magmatic volatiles in the eastern manus basin papua new guinea abstract the susu knolls and desmos hydrothermal fields are located in the back arc extensional transform zone of the eastern manus basin in 2006 highly acidic and so4 rich vent fluids were collected at both sites and analyzed for the chemical and isotopic composition of major and trace species fluids exiting the seafloor have measured temperatures from 48 to 215 c and are milky white in appearance due to precipitation of elemental s0 vent fluid concentrations of na k and mg are depleted by as much as 30 relative to seawater but have the same relative abundance in contrast the fluids are highly enriched in dissolved co2 cl sio2 aq fe and al relative to seawater measured ph 25 c ranged from 0 95 to 1 87 and aqueous so4 ranged from 35 to 135 mmol kg the chemical and isotopic composition points to formation via subsurface mixing of seawater with a na k mg and ca free volatile rich magmatic fluid exsolved from subsurface magma bodies during a process analogous to subaerial fumarole discharge estimates of the magmatic end member composition indicate a fluid phase where h2o so2 co2 cl f the hydrogen and oxygen isotopic composition of h2o and carbon isotopic composition of co2 in the vent fluids strongly suggest a contribution of slab derived h2o and co2 to melts generated in the mantle beneath the eastern manus volcanic zone abundant magmatically derived so2 undergoes disproportionation during cooling in upflow zones and contributes abundant acidity so42 and s0 to the venting fluids interaction of these highly acidic fluids with highly altered mineral assemblages in the upflow zone are responsible for extensive aqueous mobilization of sio2 aq fe and al temporal variability in the speciation and abundance of aqueous s species between 1995 and 2006 at the desmos vent field suggests an increase in the relative abundance of so2 in the magmatic end member that has mixed with seawater in the subsurface results of this study constrain processes responsible for the formation of hot spring fluids in magmatically active back arc environments and the resulting chemical exchange between the lithosphere and water column

growth history of hydrothermal black smoker chimneys hollow mineral spires known as black smoker chimneys precipitate around 350 c jets of hydrothermal fluid spouting from the sea floor on the east pacific rise epr at 21 n refs 1 2 i describe and discuss here the formation of mineral zoning across the walls of these structures throughout two major growth phases a sulphate dominated stage and a sulphide replacement stage during the sulphide replacement stage at least four distinct sulphide mineral zonation sequences develop across chimney walls from interior to exterior the apparently successive formation of these sulphide zonation sequences is attributed to evolution of radial thermal and chemical gradients accompanying the gradual thickening and sealing of black smoker chimney walls

precipitation of fe iii oxyhydroxide deposits from shallow water hydrothermal fluids in tutum bay ambitle island papua new guinea abstract previous research on sea floor fe iii oxyhydroxide deposits has focused primarily on deep sea hydrothermal systems found along volcanically active portions of the mid ocean ridges and on hydrogenetic deposits formed in deep basins and along continental shelves there is however not much known about their formation in shallow water settings associated with volcanic islands the hydrothermal system at ambitle island papua new guinea provides an excellent opportunity to study the formation of fe iii oxyhydroxides in a shallow water setting precipitation from the hydrothermal solution is caused by mixing with seawater based on a 87 sr 86 sr mixing model the calculated minimum and maximum seawater fractions are approximately 11 and 57 respectively thus precipitation of tutum bay fe iii oxyhydroxides takes place at a temperature range between approximately 60 and 93 c the chemical composition shows low mn contents fe mn 600 and elements that are usually enriched in fe iii oxyhydroxides such as co and v are below crustal abundance and well below their concentrations in island arc volcanics arsenic concentrations on the other hand are by two orders of magnitude higher than those in other marine deposits rare earth element ree concentrations reflect their concentration in the hydrothermal fluids rather than seawater the crystallinity of the deposits increases with age as protoferrihydrite is apparently altered to fe smectite and hematite and as bearing minerals are formed contact with seawater and therefore oxidizing conditions seems to be the factor increasing the crystallinity

hydrothermal fluids associated with seafloor mineralization at two southern kermadec arc volcanoes offshore new zealand massive sulfide samples have been recovered from brothers and rumble ii west volcanoes of the southern kermadec frontal arc northeast of new zealand both are caldera forming volcanoes with brothers largely dacitic and rumble ii west basaltic to basaltic andesite in composition the sulfide samples are considered to be pieces of chimneys from near the base of the caldera walls and are dominated by cu fe ba pb chalcopyrite pyrite barite galena and to a lesser extent zn fe ba pb sphalerite pyrite barite galena mineralization gold is present in the samples up to 6 1 ppm paragenetic relationships suggest that the two hydrothermal systems have heated up and later cooled down oxidation of the sulfides is common and suggests that parts of the deposits are relatively old fluid inclusion microthermometric data show salinities fall predominantly in the range 3 0 to 3 4 wt nacl equivalent similar to seawater values 3 2 wt about 15 of the brothers salinity data range to both lower 2 2 wt and higher 3 9 wt than seawater values homogenization temperatures for type i inclusions in barite range between 175 and 322 c for the brothers samples and between 205 and 268 c for one rumble ii west sample a dramatic decrease in temperature and or change in the oxidation state of the hydrothermal fluid are considered the main mechanisms responsible for gold deposition at the kermadec vent sites this was achieved by mixing the hydrothermal fluid with ambient seawater within what are inferred to have been 300 c white smoker chimneys consistent with s isotope results fluid inclusion volatiles are dominated by h2o 99 81 99 98 mol followed by co2 0 03 0 17 and lesser amounts of n2 0 004 0 023 ch4 0 002 0 026 and trace cos and c2 c3 hydrocarbons fluid inclusions hosted by barite contain noticeably lesser amounts of gas than those within sulfides consistent with mixing the source of the relatively high concentrations of ch4 is enigmatic although may be related to the thermal degradation of organic rich sediments intercalated within the volcanic pile addition of a pressure correction and the effect of dissolved gases show that the hydrothermal fluids did not boil at the chimney depths however the range of measured salinities in the brothers field combined with slightly positive trends in fluid inclusion co2 ch4 versus co2 n2 plots suggest sub seafloor phase separation may have occurred in the hydrothermal system prior to venting

quantified multi scale x ray fluorescence element mapping using the maia detector array application to mineral deposit studies the maia large solid angle detector array and imaging system is capable of collecting high resolution images of up to 100 m pixels in size with dwell times of less than 0 2 ms per pixel and thus it is possible to document variation in textures associated with trace element chemistry by collecting quantified elemental maps of geological samples on the scale of entire thin sections in a short time frame 6 8 hr the analysis is nondestructive and allows variation to be recognised on a centimetre scale while also recognising zonations at the micron scale

seafloor bioalteration of sulfide minerals results from in situ incubation studies we present results of incubation studies conducted at low temperatures 4 c in the vicinity of a seafloor hydrothermal vent system we reacted fe s cu and zn bearing minerals including pyrite marcasite chalcopyrite sphalerite elemental sulfur and a portion of a natural chimney sulfide structure for 2 months at the main endeavour segment of the juan de fuca ridge in the pacific ocean our study utilizes fluorescent in situ hybridizations fish scanning and transmission electron microscopy sem tem and light microscopic analysis the surfaces of these minerals are solely colonized by bacteria and not by archaea colonization densities vary over an order of magnitude with the following sequence elemental sulfur chimney sulfide marcasite pyrite sphalerite chalcopyrite and correspond well with the abiotic oxidation kinetics of these materials excepting elemental sulfur which is both the least reactive to oxidizing species and the most heavily colonized colonization densities also correspond with apparent degree of reaction dissolution pitting accumulation of secondary alteration products heavy accumulations of secondary fe oxides on fe bearing minerals most notably on the chimney sulfide form in situ as the result of mineral dissolution and the activity of neutrophilic fe oxidizing bacteria results suggest that mineral oxidizing bacteria play a prominent role in weathering of seafloor sulfide deposits and that microbial utilization of mineral substrates contributes to biomass production in seafloor hydrothermal environments

hydrothermal activity on the southern mid atlantic ridge tectonically and volcanically controlled venting at 4 5 s we report results from an investigation of the geologic processes controlling hydrothermal activity along the previously unstudied southern mid atlantic ridge 3 7 s our study employed the noc uk deep tow sidescan sonar instrument tobi in concert with the whoi usa autonomous underwater vehicle abe to collect information concerning hydrothermal plume distributions in the water column co registered with geologic investigations of the underlying seafloor two areas of high temperature hydrothermal venting were identified the first was situated in a non transform discontinuity ntd between two adjacent second order ridge segments near 4 02 s distant from any neovolcanic activity this geologic setting is very similar to that of the ultramafic hosted and tectonically controlled rainbow vent site on the northern mid atlantic ridge the second site was located at 4 48 s at the axial summit centre of a second order ridge segment there high temperature venting is hosted in an 18 km2 area of young lava flows which in some cases are observed to have flowed over and engulfed pre existing chemosynthetic vent fauna in both appearance and extent these lava flows are directly reminiscent of those emplaced in winter 2005 06 at the east pacific rise 9 50 n and reference to global seismic catalogues reveals that a swarm of large m 4 6 5 6 seismic events was centred on the 5 s segment over a 24 h period in late june 2002 perhaps indicating the precise timing of this volcanic eruptive episode temperature measurements at one of the vents found directly adjacent to the fresh lava flows at 5 s mar turtle pits have subsequently revealed vent fluids that are actively phase separating under conditions very close to the critical point for seawater at 3000 m depth and 407 c the hottest vent fluids yet reported from anywhere along the global ridge crest

life on the edge microbial biomineralization in an arsenic and lead rich deep sea hydrothermal vent abstract unravelling complex microbial activity in modern hydrothermal vents can provide crucial insights into the evolution of ancient life on earth it is well established that microorganisms in hydrothermal vents have a significant impact on the cycling of metals and mineral formation however the detailed roles played by microorganisms in driving sulfide deposition and cycling of toxic metals like arsenic as and lead pb in high temperature deep sea hydrothermal vents remain unknown the understanding of these mechanisms in extreme environments is of particular importance as as has been postulated as a driver of microbial activities on the early earth here we present the first geologic evidence of pb as rich microbial filamentous clusters observed in a modern high temperature black smoker from the manus back arc basin papua new guinea the clusters occur as net like structures on the surface of barite and sulfides and are composed of multiple filaments and fine grained pb as sulfosalt each of the filaments includes an as pb rich sulfosalt core and organic rich shell structure with elevated carbon nitrogen and phosphorus further synchrotron x ray absorption near edge structure analysis shows that the clusters contain a mixture of as ii and as iii additionally those filaments show a close association with realgar as4s4 by penetrating and dissolving this as sulfide mineral we interpret the filaments to be a result of as related microbial activity in as and pb enriched hydrothermal environments the findings show possible processes through which extremophiles live in pb and as rich environments during chimney growth in addition as hydrothermal vents are regarded as modern analogs of ancient volcanogenic massive sulfide deposits the observed biominerals present the potential to be used as proxies to trace the signatures of early life in ancient geological systems

the garmsar salt nappe and seasonal inversions of surrounding faults imaged by sar interferometry northern iran the allochthonous tertiary salt of the garmsar salt nappe extruded from where the most southerly point of the alborz mountain front is offset by the zirab garmsar strike slip fault we used eleven descending advanced synthetic aperture radar sar images acquired by the euro pean space agency s envisat satellite from 2003 to 2006 to map surface displacement over 23 increments ranging in time from 30 to 2 months a 30 month sar interferogram of the area shows that the regional folds and faults are active south of the mountain front but are dampened by the allochthonous salt that otherwise appears to be merely degrading at rates that vary with the season interferograms for shorter epochs display different patterns of fault blocks in the country rocks that rose and fell with the seasons by relating surface displacements mapped in these interferograms to the contemporaneous seismic record we find that seismic faults reactivate repeatedly while their kinematics may have inverted on remarkably short timescales seismic disturbances propagate very slowly and faults are longer than expected for earthquakes with ml 3 5 indicating that the regional strains are more aseismic than anticipated by earlier studies

210pb dating of cold alpine firn ice cores from colle gnifetti switzerland datation 210 pb 210 po d une carotte de glacier froid le taux d accumulation corrige est de 39 cm an pour une carotte de 1977 65 m

distribution speciation and bioavailability of arsenic in a shallow water submarine hydrothermal system tutum bay ambitle island png shallow water hydrothermal vent systems can introduce large amounts of potentially toxic elements such as arsenic as into coastal marine environments the first step in understanding and describing the potential impact of these elements throughout hydrothermally influenced coastal ecosystems is to determine the element s distribution and speciation which in turn influences the availability of the toxin for biological uptake shallow submarine hot springs near ambitle island papua new guinea are discharging as much as 1 5 kg per day of arsenic directly into a coral reef ecosystem we have investigated the bioavailability of the as throughout tutum bay by studying vent fluid seawater pore water precipitates and sediments in addition to measuring as abundance as speciation as iii as v and the methylated species dma and mma was determined in various waters the as concentration for discrete mineral phases in vent precipitates and sediments was determined by sequentially extracting arsenic from the easily extractable carbonate fe oxyhydroxide or hydrous ferric oxide hfo and residual fractions each of which have a different bioavailability diffuse venting seems to play a critical role on the distribution of as throughout tutum bay surface sediments which have a mean as concentration of 527 ppm while excluding the vent precipitates range 1483 to 52 ppm up to 54 ppm as were extracted from the easily extractable fraction of surface sediments mean 19 7 ppm using a k2hpo4 kh2po4 buffer at ph 7 2 arsenic from this fraction is considered to be the most available for biological processes and therefore the most dangerous for biota however sequential extraction shows that 98 6 of the as in vent precipitates and a mean of 93 3 in surface sediments range 88 2 to 96 3 is coprecipitated with the hydrous ferric oxide hfo fraction thus the bulk of the as being discharged into tutum bay is scavenged by the hfo and should remain stable unless the physicochemical conditions surrounding the oxides change in surface seawaters of tutum bay we found as much as four times the average seawater concentration of as 8 4 ag l compared to 2 ag l the abundance of as in seawater just above the sediment water interface is near normal although as iii in both surface and bottom seawater throughout tutum bay is substantially enriched compared to average seawater hydrothermal venting therefore provides bioavailable as by two major pathways throughout tutum bay 1 easily exchangeable as from hydrothermally influenced sediments to as far away as 200 m from focused venting and 2 in surface seawaters which may allow for biological uptake by phytoplankton and transfer up the food web d 2005 elsevier b v all rights reserved

geochemistry of hydrothermal fluids from the pacmanus northeast pual and vienna woods hydrothermal fields manus basin papua new guinea abstract processes controlling the composition of seafloor hydrothermal fluids in silicic back arc or near arc crustal settings remain poorly constrained despite growing evidence for extensive magmatic hydrothermal activity in such environments we conducted a survey of vent fluid compositions from two contrasting sites in the manus back arc basin papua new guinea to examine the influence of variations in host rock composition and magmatic inputs both a function of arc proximity on hydrothermal fluid chemistry fluid samples were collected from felsic hosted hydrothermal vent fields located on pual ridge pacmanus and northeast ne pual near the active new britain arc and a basalt hosted vent field vienna woods located farther from the arc on the manus spreading center vienna woods fluids were characterized by relatively uniform endmember temperatures 273 285 c and major element compositions low dissolved co 2 concentrations 4 4 mmol kg and high measured ph 4 2 4 9 at 25 c temperatures and compositions were highly variable at pacmanus ne pual and a large newly discovered vent area fenway was observed to be vigorously venting boiling 358 c fluid all pacmanus fluids are characterized by negative d h 2 o values in contrast to positive values at vienna woods suggesting substantial magmatic water input to circulating fluids at pual ridge low measured ph 25 c values 2 6 2 7 high endmember co 2 up to 274 mmol kg and negative 34 s h 2 s values down to 2 7 in some vent fluids are also consistent with degassing of acid volatile species from evolved magma dissolved co 2 at pacmanus is more enriched in 13 c 4 1 to 2 3 than vienna woods 5 2 to 5 7 suggesting a contribution of slab derived carbon the mobile elements e g li k rb cs and b are also greatly enriched in pacmanus fluids reflecting increased abundances in the crust there relative to the manus spreading center variations in alkali and dissolved gas abundances with cl at pacmanus and ne pual suggest that phase separation has affected fluid chemistry despite the low temperatures of many vents in further contrast to vienna woods substantial modification of pacmanus ne pual fluids has taken place as a result of seawater ingress into the upflow zone consistently high measured mg concentrations as well as trends of increasingly non conservative so 4 behavior decreasing endmember ca cl and sr cl ratios with increased mg indicate extensive subsurface anhydrite deposition is occurring as a result of subsurface seawater entrainment decreased ph and endmember fe mn ratios in higher mg fluids indicate that the associated mixing cooling gives rise to sulfide deposition and secondary acidity production several low temperature 80 c fluids at pacmanus ne pual also show evidence for anhydrite dissolution and water rock interaction fixation of b subsequent to seawater entrainment hence the evolution of fluid compositions at pual ridge reflects the cumulative effects of water rock interaction admixing and reaction of fluids exsolved from silicic magma phase separation segregation and seawater ingress into upflow zones

arsenic in hot springs of bahia concepcion baja california peninsula mexico abstract high arsenic concentrations 0 15 to 0 78 mg l were measured in water discharged from hydrothermal vents at bahia concepcion baja california sur additionally concentrations above the average for the continental crust 1 8 mg kg were determined in rocks and marine sediments rock samples collected around intertidal and submarine hydrothermal discharges are encrusted by deposits of opaline silica barite calcite and mn oxides and in subordinate amounts of pyrite and ferrihydrite sequential extraction showed that arsenic is adsorbed mainly on amorphous and crystalline iron oxides and in lower concentrations to the easily extractable phase when hydrothermal fluids mix with oxidizing and alkaline seawater ph about 8 3 arsenic in h 3 aso 3 is oxidized to form h 2 aso 4 or possibly a deprotoned form such as haso 4 2 in addition reduced iron from the hydrothermal fluid is oxidized to ferric ion and forms non crystalline ferric hydroxide fe oh 3 which is able to adsorb arsenic x ray elemental maps of the surface of the rock samples located near the submarine discharges show evidence that arsenate is adsorbed onto calcite surface iron oxyhydroxides with adsorbed as could be present on the seafloor forming deposits of flocculent material which can be incorporated into the tissue of some marine organisms e g holothurians that feed in the vicinity of the hydrothermal manifestations oxidation and adsorption processes control transport and mobilization of arsenic in bahia concepcion hydrothermal fluids

sulfide impregnated and pure silica precipitates of hydrothermal origin from the central indian ocean abstract this is the first report about silica rich hydrothermal precipitates which were sampled together with hydrothermal sulfides chimney fragments in an extinct vent field in the central indian ocean there are two kinds of silica rich rocks a jasper which is impregnated and replaced to various degrees mainly by sphalerite and to a lesser extent by barite pyrite and traces of chalcopyrite and an opalite which is an almost pure silica phase without any sulfide or sulfate impregnations but which is sometimes covered by manganese crusts no internal concentric zoning indicating typical chimney structures can be recognized in the jasper and or opalite samples the textures rather suggest a sedimentary silica and or iron deposition from diffuse low temperature 60 c vent fluids partly with still visible indications of former bacterial mats and synsedimentary deformation structures the sphalerite and barite impregnations within the jasper however are considered to have precipitated from white smoker type fluids since they were deposited under intermediate temperatures between 155 and 265 c according to fluid inclusion studies the sulfur isotopic composition 34 s of our sulfide samples has mean values of 6 1 for sphalerite and 5 7 for pyrite indicating a mixture of predominantly basaltic sulfur with subordinate amounts of reduced seawater sulfur the oxygen isotope signals of some pure jasper concentrate samples indicate that the mean formation temperature calculated from these values lies at 63 2 c the relationship between the massive pyrite and chalcopyrite ores from the extinct chimney structures and the silica rich precipitates can be explained by different cycles of hydrothermal activity one high temperature above 300 c cycle dominated by pyrite and chalcopyrite formation and one later epithermal below 300 c cycle which resulted in sphalerite and silica dominated precipitates furthermore zonation and zone refining processes are part of the evolution of the mineralized field

chemical microenvironments within sulfide structures from the mothra hydrothermal field evidence from high resolution zoning of trace elements abstract massive portions of a 300 c black smoker finn and a diffusely venting intermediate temperature 200 c chimney roane recovered from the mothra hydrothermal field on the juan de fuca ridge have been analyzed in detail for bulk chemistry the size of the recovered pieces of chimney enabled physical segregation and analysis of distinct chemical zonation within the structures in particular large variations in the concentrations of minor and trace elements in the different mineralogical zones provide new insight into the processes involved in chimney growth that are not evident from the bulk mineralogy systematic zonation of trace and minor elements is strongly influenced by redox conditions multiple host phases single or dual fluid source and the mixing cooling history of the fluids even within an individual mineralogical zone distinct chemical microenvironments within the chimneys are recognized that provide a basis for detailed reconstruction of the changing conditions in the interiors of the chimneys during their growth in finn 14 discrete chemical microenvironments are recognized in 80 of 90 samples based on high resolution zoning of major and trace elements four of the microenvironments are cu rich three are zn rich one is fe rich with low cu two are ca rich three are sio2 rich and one is ba and sio2 rich in roane 24 discrete chemical microenvironments are recognized six of the microenvironments are sio2 poor

origin of methane in serpentinite hosted hydrothermal systems the ch4 h2 h2o hydrogen isotope systematics of the hakuba happo hot spring abstract serpentinite hosted hydrothermal systems have attracted considerable attention as sites of abiotic organic synthesis and as habitats for the earliest microbial communities here we report a systematic isotopic study of a new serpentinite hosted system the hakuba happo hot spring in the shiroumadake area japan 36 42 n 137 48 e we collected water directly from the hot spring from two drilling wells more than 500 m deep all water samples were strongly alkaline ph 10 and rich in h2 201 664 mol l and ch4 124 201 mol l despite the relatively low temperatures 50 60 c thermodynamic calculations suggest that the h2 was likely derived from serpentinization reactions hydrogen isotope compositions for happo 1 happo 3 were found to be as follows d h 2 700 710 d ch 4 210 300 and d h 2 o 85 84 the carbon isotope compositions of methane from happo 1 and 3 were found to be c 13 34 5 and 33 9 respectively the ch4 h2 h2o hydrogen isotope systematics indicate that at least two different mechanisms were responsible for methane formation happo 1 has a similar hydrogen isotope compositions to other serpentinite hosted systems reported previously the elevated d ch 4 with respect to the equilibrium relationship suggests that the hydrogen of the happo 1 methane was not sourced from molecular hydrogen but was derived directly from water this implies that the methane may not have been produced via the fischer tropsch type ftt synthesis but possibly by the hydration of olivine conversely the depleted d ch 4 with respect to the equilibrium relationship in happo 3 suggests the incorporation of biological methane based on a comparison of the hydrogen isotope systematics of our results with those of other serpentinite hosted hydrothermal systems we suggest that abiotic ch4 production directly from h2o without mediation by h2 may be more common in serpentinite hosted systems hydration of olivine may play a more significant role in abiotic methane production than previously thought

the susu knolls hydrothermal field eastern manus basin papua new guinea an active submarine high sulfidation copper gold system susu knolls comprises three steep sided conical volcanic peaks standing on a n nw trending ridge in the eastern manus basin a complex zone of convergence between the major indo australian and pacific plates the knolls consist of three porphyritic andesite to dacite domes each 1 0 to 1 5 km in diameter with crests ranging from 1 150 to 1 520 m below sea level an intense hydrothermal plume with peak transmission anomalies in excess of 40 originates from susu knolls and associated hydrothermal venting with fluid temperatures exceeding 300 c and sulfide mineralization has been detected on the crests of all three edifices the most important of these is the 2 47 million metric ton mt solwara 1 copper gold deposit on suzette knoll slated for mining by nautilus minerals the porphyritic dacite is commonly strongly altered by reaction with acidic fluids fragments of sulfide mineralization collected as part of the seafloor talus surrounding the crest of north su and south su are characterized by an assemblage of pyrite fukuchilite enargite covellite chalcopyrite by contrast there are actively venting chimneys on the crest of suzette that are typically zoned with chalcopyrite pyrite tennantite inner zones and barite dominated outer zones the knolls are covered by black sulfidic sediments that contain up to 2 4 wt cu and 3 2 ppm au primary feldspars have been obliterated by the hydrothermal activity that ranges from incipient to intense and which is characterized by natroalunite alunite north su only cristobalite tridymite and rare quartz and kaolinite most volcanic rocks exhibit a patchy surficial coating of native sulfur which may also fill vesicles no altered rocks were dredged from suzette because of the thick sulfidic sediment cover mass balance calculations for altered and unaltered rock from north and south su show that major and trace lithophile elements are depleted in the altered rocks except for ti al si and zr all near immobile in concert with the destruction of the primary minerals and removal of primary components by acidic fluids sulfur and chalcophile trace elements i e as au ba cd cu mo pb and se typically associated with magmatic cu au mineralization are enriched by orders of magnitude in both leached and mineralized rock sulfide and native sulfur 34s values from all three domes range from 7 4 to 0 4 indicating a magmatic component for the sulfur a small group of ore elements i e ag bi in sb and zn are strongly enriched in mineralized breccias and depleted in the altered dacites suggesting redistribution during alteration the presence of advanced argillic alteration the paragenesis of the fe cu as sulfide assemblage and presence of native sulfur together with the sulfur isotope evidence for magmatic input into the hydrothermal fluid at susu knolls are consistent with a submarine high sulfidation magmatic cu au hydrothermal system furthermore the sulfide assemblage pyrite enargite covellite chalcopyrite observed at north and south su and orders of magnitude enrichment of chalcophile elements in both altered and mineralized volcanic rocks relative to unaltered volcanic rock are also characteristic of subaerial high sulfidation epithermal mineralization the susu knolls hydrothermal field is a good example of a modern high sulfidation cu au submarine hydrothermal system

microbial diversity and potential for arsenic and iron biogeochemical cycling at an arsenic rich shallow sea hydrothermal vent tutum bay papua new guinea the shallow submarine hydrothermal systems of tutum bay papua new guinea are an ideal opportunity to study the influence of arsenic on a marine ecosystem previous reports have demonstrated that the hydrothermal vents in tutum bay release arsenic in reduced hydrothermal fluids into the marine environment at the rate of 1 5 kg of arsenic day aqueous arsenite is oxidized and adsorbed onto hydrous ferric oxides hfos surrounding the venting area we demonstrate here that microorganisms are key in both the oxidation of fe ii and as iii in the areas immediately surrounding the vent source surveys of community diversity in biofilms and in vent fluid indicate the presence of zeta proteobacteria alpha proteobacteria persephonella and close relatives of the archaeon nitrosocaldus the iron oxidizing zeta proteobacteria are among the first colonizers of solid substrates near the vents where they appear to be involved in the precipitation of the hydrous ferric oxides hfos further the biofilm communities possess the genetic capacity for the oxidation of arsenite the resulting arsenate is adsorbed onto the hfos potentially removing the arsenic from the immediate marine system no evidence was found for dissimilatory arsenate reduction but the arsenate may be remobilized by detoxification mechanisms this is the first demonstration of the genetic capacity for arsenic cycling in high temperature shallow sea vent communities supporting recent culture based findings in similar systems in greece handley et al 2010 these reports extend the deep sea habitat of the zeta proteobacteria to shallow submarine hydrothermal systems and together implicate biological oxidation of both iron and arsenite as primary biogeochemical processes in these systems providing a mechanism for the partial removal of aqueous arsenic from the marine environment surrounding the vents

associations between sulfides carbonaceous material gold and other trace elements in polyframboids implications for the source of orogenic gold deposits otago schist new zealand abstract intimately intergrown micron scale framboidal pyrite carbonaceous material cm chalcopyrite sphalerite and cobaltite form polyframboids in prehnite pumpellyite facies rocks of the otago schist new zealand this study quantifies the metal contents of these polyframboids using synchrotron x ray fluorescence sxrf and laser ablation inductively coupled plasma spectrometry la icp ms trace elements au zn as mo co ni cu ag and pb are significantly enriched in the polyframboids the distribution of zn most closely follows that of cm and was probably absorbed into the structure of the polyframboids during biogenic processes the concentrations of au and ag are positively corrected with the zn concentration in the polyframboids r2 of au zn and ag zn are 0 81 and 0 89 respectively the concentration of other trace elements such as as co and cu which occur adjacent to zn on elemental maps show a weak relationship with zn and may have been incorporated into the polyframboids during later processes these polyframboids are a probable source for gold and other elements in the orogenic gold mineralization system of the otago schist metamorphic transformation of the polyframboids may have released the metallic elements into the mineralizing fluid during prograde metamorphism of the schist belt