epithermal gold mineralisation in the active aegean volcanic arc the profitis ilias deposit milos island greece the profitis ilias gold deposit located on the western part of milos island greece is the first epithermal gold deposit discovered in the pliocene pleistocene aegean volcanic arc estimated ore reserves are 5 million tonnes grading 4 4 g tonne au and 43 g tonne ag the deposit is closely associated with a horst and graben structure and occurs in a series of steep interconnected crustiform banded quartz veins up to 3 m wide extending to depths of at least 300 m the mineralisation occurs in three stages and is hosted by 3 5 2 5 ma old silicified and sericitised rhyolitic lapilli tuffs and ignimbrites it consists of pyrite galena chalcopyrite electrum and native gold additionally adularia occurs with quartz mainly in veins homogenisation temperatures of primary liquid rich inclusions vary from 145 to 399 c for the ore stage and 112 to 263 c for the post ore stage salinities range between 0 1 and 11 4 wt nacl equiv and 0 93 to 8 5 wt nacl equiv for the ore stage and the post ore stage respectively rare vapour rich inclusions in ore stage quartz homogenise between 368 and 399 c and estimates of eutectic melting 25 to 38 c indicate the presence of ca and mg in the ore fluids sample elevation versus fluid inclusion th salinity relationships show 1 a high salinity trend where moderate temperature 300 250 c and moderate salinity brines 3 wt nacl equiv trend to high salinity up to 15 wt nacl equiv fluids with lower 25 50 c homogenisation temperatures and 2 a high th trend where moderate salinity and moderate temperature brines 200 250 c 3 wt nacl equiv develop into low salinity 350 c fluids these trends are best explained by extreme boiling and vapourisation phenomena between 200 and 250 c the 430 450 m asl metres above sea level level marks the transition between a lower liquid dominated segment of the system where only the steep high salinity trend is seen and an upper vapour dominated segment where the high th trend or a combination of both are seen there is a close spatial association between mineable gold grades and the upper segment of the system depth to boiling curves suggest that the paleo surface was 200 m above the present summit of profitis ilias comparison of the mineralisation and fluid geochemistry at profitis ilias with that of the nearby modern geothermal system indicates that the processes of metal mineralisation have probably been continuous since the late pliocene

southern kermadec submarine caldera arc volcanoes sw pacific caldera formation by effusive and pyroclastic eruption abstract three newly identified submarine caldera volcanoes brothers healy and rumble ii west of the southern kermadec arc within water depths 80 and low density 0 3 0 5 g cm 3 erupted pumiceous clasts these observations are interpreted as evidence of subaqueously quenched pyroclastic eruption s sheathed by ambient water flashing to steam discharging some 5 km3 of pyroclastic material from healy volcano caldera collapse is inferred to be penecontemporeous with the pyroclastic eruption s although it is possible formation as an explosive crater occurred but we consider the latter unlikely given the volume of erupted material and water depth extrapolation of these observations to other submarine arcs indicates pyroclastic eruption of silicic magmas and syn eruptive caldera collapse is possible within water depths of 500 1000 m

the development of volcanic hosted massive sulfide and barite gold orebodies on wetar island indonesia wetar island is composed of neogene volcanic rocks and minor oceanic sediments and forms part of the inner banda arc the island preserves precious metal rich volcanogenic massive sulfide and barite deposits which produced approximately 17 metric tonnes of gold the polymetallic massive sulfides are dominantly pyrite locally arsenian with minor chalcopyrite which are cut by late fractures infilled with covellite chalcocite tennantite tetrahedrite enargite bornite and fe poor sphalerite barite orebodies are developed on the flanks and locally overly the massive sulfides these orebodies comprise friable barite and minor sulfides cemented by a series of complex arsenates oxides hydroxides and sulfate with gold present as 10 m free grains linear and pipe like structures comprising barite and iron oxides beneath the barite deposits are interpreted as feeder structures to the barite mineralization hydrothermal alteration around the orebodies is zoned and dominated by illite kaolinite smectite assemblages however local alunite and pyrophyllite are indicative of late acidic oxidizing hydrothermal fluids proximal to mineralization altered footwall volcanic rocks give an illite k ar age of 4 7 0 16 ma and a 40ar 39ar age of 4 93 0 21 ma fluid inclusion data suggest that hydrothermal fluid temperatures were around 250 270 c showed no evidence of boiling with a mean salinity of 3 2 wt equivalent nacl the 34s composition of sulfides ranges between 3 3 and 11 7 and suggests a significant contribution of sulfur from the underlying volcanic edifice the 34s barite data vary between 22 4 and 31 0 close to miocene seawater sulfate whole rock 87sr 86sr analyses of unaltered volcanic rocks 0 70748 0 71106 reflect contributions from subducted continental material in their source region the 87sr 86sr barite data 0 7076 0 7088 indicate a dominant miocene seawater component to the hydrothermal system the mineral deposits formed on the flanks of a volcanic edifice at depths of 2 km spectacular sulfide mounds showing talus textures are localized onto faults which provided the main pathways for high temperature hydrothermal fluids and the development of associated stockworks the orebodies were covered and preserved by post mineralization chert gypsum globigerina bearing limestone lahars subaqueous debris flows and pyroclastics rocks

volcanology and petrology of volcanic products from the island of milos and neighbouring islets abstract new geochronological and volcanological data from volcanics of the island group of milos south aegean active volcanic arc allow four main cycles of volcanic activity to be distinguished ranging in age between 3 5 and 0 1 m y b p the oldest volcanic activity consists almost totally of pyroclastics and submarine products followed by subaerial ones the eruptive centers migrated in time and concentrated during the most recent volcanic phase in the central part of milos and on the island of antimilos the oldest products are dominated by andesites and dacites while the most recent ones mainly consist of rhyolites the volcanic evolution and the geochemical characters of the erupted products suggest that the feeding system of the oldest volcanism was located in the deep continental crust where contamination and fractional crystallization jointly occurred the younger cycle of volcanic activity was fed from small and relatively shallow magma chambers where contamination processes played a minor role these magma bodies are considered to responsible for the shallow thermal anomaly giving rise to the high enthalpy field on milos

properties origin and nomenclature of rodlets of the inertinite maceral group in coals of the central appalachian basin u s a abstract resin rodlets sclerenchyma strands and woody splinters which are collectively called rodlets were studied by chemical optical petrographic and scanning electron microscopic sem techniques a study was made of such rodlets from the bituminous coal beds of the central appalachian basin pennsylvanian upper carboniferous of the united states comparisons were made with rodlets from coal beds of the illinois basin the southern anthracite field of pennsylvania the st rose coal field of nova scotia and european and other coal fields in order to determine their physical and chemical properties a detailed study was made of the rodlets from the pomeroy coal bed high volatile a bituminous coal monongahela formation upper pennsylvanian of kanawha county west virginia the origin of the rodlets was determined by a comparative analysis of a medullosan seed fern stem from the herrin no 6 coal bed high volatile c bituminous coal carbondale formation from washington county illinois rodlets are commonly concentrated in fusain or carbominerite layers or lenses in bituminous coal beds of the central appalachian basin most of the rodlets examined in our study were probably derived from medullosan seed ferns the three types of rodlets are distinguished on the basis of cellularity morphology and fracture the resin rodlets studied by us are noncellular and appear to be similar in properties and origin to those found in coal beds of the middle and upper pennsylvanian of the illinois basin the resin rodlets extracted from the pomeroy coal bed exhibit high relief and high reflectance when polished and viewed in reflected light they are opaque in transmitted light in cross section the resin rodlets are oval to round and have diameters ranging from 60 to 450 m many are solid but some have vesicles canals or cavities which are commonly filled with clay probably kaolinite typically they have distinct fracture patterns kerfs in longitudinal and cross sections and many are characterized by dense probably oxidized rims the orientation and amounts of void space and mineralization of resin rodlets in coal have resulted in much confusion in their recognition and classification the resin rodlets are petrographically recognized as sclerotinites of the inertinite maceral group we here propose that resin rodlets be assigned to the maceral variety of sclerotinites termed resino sclerotinite because of their presumable resinous origin other investigators have confused some fusinitized resin rodlets with fungal masses which have different morphological properties and which probably have different chemical properties we here propose that such fungal masses be assigned to the maceral variety of sclerotinites termed fungo sclerotinite the sclerenchyma strands examined in our study are cellular thick walled and crescent shaped in cross section they exhibit high reflectance and high relief and belong to semifusinite and fusinite of the inertinite maceral group sclerenchyma strands are commonly associated with resin canals in medullosa and related seed fern genera which are common in coal balls of the illinois basin we here propose adoption of the maceral varietal terms sclerenchymo fusinite and sclerenchymo semifusinite for these bodies the woody splinters in the pomeroy coal bed are cellular and thin walled and have scattered pits as much as a few microns in diameter they are dark brown to black in transmitted light and commonly have a lower reflectance than the resino sclerotinite and sclerenchymo fusinite of the pomeroy coal the woody splinters belong to semifusinite and fusinite of the inertinite maceral group the maceral varietal terms xylemo semifusinite and xylemo fusinite are here proposed for these bodies elemental chemical data for the resin rodlets of the pomeroy coal bed of the central appalachian basin indicate that resin rodlets have significantly lower atomic h c and o c ratios than do sclerenchyma strands and woody splinters the lower atomic h c and o c ratios of the resin rodlets correlate with the highest reflectance in the coal ball medullosan seed fern stem from the herrin no 6 coal bed of the illinois basin the reflectances of the resin rodlets woody splinters and sclerenchyma strands are similar and comparable to those of associated vitrinite in the coal ball stem and in the attached coal however resin rodlets and sclerenchyma strands in the attached coal have significantly higher reflectances similar to those of the pomeroy coal

the abundance of seafloor massive sulfide deposits the possibility of mining seafl oor massive sulfide deposits has stirred debate about the sustainable use of this new resource and whether commercial development is worth the risk among the outstanding questions is how many deposits might be accessible to deep sea mining more than 300 sites of high temperature hydrothermal venting have been identifi ed since the discovery of black smokers but signifi cant massive sulfide accumulation has been found at only 165 of these sites estimates of the total number of vent fields and associated mineral deposits based on plume studies and deposit occurrence models range from 500 to 5000 we have used new deposit occurrence data from 10 000 km of ridge arc and backarc spreading centers to estimate the amount of massive sulfide in the easily accessible neovolcanic zones of the global oceans the total accumulation in these areas is estimated to be on the order of 6 108 tonnes containing 3 107 tonnes of copper and zinc this is similar to the total discovered copper and zinc in cenozoic massive sulfi de deposits mined on land but is insuffi cient to satisfy a growing global demand for these metals

products and timing of diagenetic processes in upper rotliegend sandstones from bebertal north german basin parchim formation flechtingen high germany aeolian fluvial upper rotliegend sandstones from bebertal outcrops flechtingen high north germany are an analogue for deeply buried permian gas reservoir sandstones of the north german basin ngb we present a paragenetic sequence as well as thermochronological constraints to reconstruct the diagenetic evolution and to identify periods of enhanced mesodiagenetic fluid rock reactions in sandstones from the southern flank of the ngb bebertal sandstones show comparatively high concentrations of mesodiagenetically formed k feldspar but low concentrations of illite cements illite rich grain rims were found to occur preferentially directly below sedimentary bounding surfaces i e aeolian superimposition surfaces and indicate the lowest intergranular volume illite grain rims also indicate sandstone sections with low quartz and feldspar cement concentrations but high loss of intergranular volume due to compaction 40ar 39ar age determination of pronounced k feldspar grain overgrowths and replacements of detrital grains indicates two generations an early triassic and a late jurassic generation the latter age range is similar to published diagenetic illite ages from buried rotliegend reservoir sandstones the first generation suggests an early intense mesodiagenetic fluid flow with remarkably high k activity synchronous with fast burial of proximal initial graben sediments on the southern flank of the ngb accordingly zircon fission track data indicate that the strata already reached the zircon partial annealing zone of approximately 200 c during early mesodiagenesis zircon u th he ages 92 12 ma as well as apatite fission track ages 71 75 ma indicate the termination of mesodiagenetic processes caused by rapid exhumation of the flechtingen high during late cretaceous basin inversion

numerical model to determine the composition of h2o nacl cacl2 fluid inclusions based on microthermometric and microanalytical data natural fluids approximated by the h2o nacl cacl2 system are common in a wide range of geologic environments including sedimentary basins associated with hydrocarbon occurrences and mvt deposits submarine hydrothermal systems and other metamorphic magmatic and hydrothermal environments we present a comprehensive numerical model and microsoft excel based computer program to determine the compositions of fluid inclusions in the h2o nacl cacl2 system based on microthermometric and microanalytical data the model consists of six polynomial correlation equations that describe liquid salinity as a function of nacl cacl2 ratio and melting temperature on each of the ice hydrohalite halite antarcticite cacl2 4h2o and cacl2 2h2o vapor saturated liquidus surfaces the cotectic and peritectic boundaries are determined from the intersections of the liquidus surfaces the model is implicitly internally consistent and topologically correct the model expands upon the compositional range of applicability and the data types that can be used for compositional determination it reproduces experimental data for all compositions that lie within the h2o nacl cacl2 4h2o compositional triangle in the h2o nacl cacl2 system and yields accurate reproductions of the h2o nacl and h2o cacl2 binaries furthermore in comparison to previously published models the one presented here eliminates systematic errors wavy isotherms and cotectic and peritectic curves with local bumps

petrography and microanalysis of pennsylvanian coal ball concretions herrin coal illinois basin usa bearing on fossil plant preservation and coal ball origins abstract petrographic analyses of 25 coal balls from well studied paleobotanical profiles in the middle pennsylvanian herrin coal westphalian d illinois basin and five select coal balls from university collections indicate that herrin coal ball peats were permineralized by fibrous and non fibrous carbonates fibrous carbonates occur in fan like to spherulitic arrays in many intracellular within tissue pores and are best developed in relatively open extracellular between plant pore spaces acid etched fibrous carbonates appear white under reflected light and possess a microcrystalline texture attributable to abundant microdolomite scanning electron microscopy x ray diffraction and electron microprobe analysis demonstrate that individual fibers have a distinct trigonal prism morphology and are notable for their magnesium content 9 15 mol mgco 3 non fibrous carbonates fill intercrystalline spaces among fibers and pores within the peat as primary precipitates and neomorphic replacements in the immediate vicinity of plant cell walls non fibrous carbonates cut across fibrous carbonates as a secondary neomorphic phase attributed to coalification of plant cell walls dolomite occurs as diagenetic microdolomite associated with the fibrous carbonate phase as sparite replacements and as void filling cement maximum dolomite 50 59 wt is in the top of seam coal ball zone at the sahara mine which is overlain by the marine anna shale coal ball formation in the herrin coal began with the precipitation of fibrous high magnesium calcite the trigonal prism morphology of the carbonate fibers suggests rapid precipitation from super saturated meteoric pore waters carbonate precipitation from marine waters is discounted on the basis of stratigraphic paleobotanical and stable isotopic evidence most non fibrous carbonate is attributable to later diagenetic events including void fill replacements recrystallization and post depositional fracture fills evidence suggests that co 2 degassing was important in coal ball formation in the herrin coal which mainly occurred sequentially upward with peat accumulation in the sites studied

coalification of organic matter in coal balls of the pennsylvanian upper carboniferous of the illinois basin united states abstract an evaluation was made of the degree of coalification of two coal balls from the illinois basin of the pennsylvanian upper carboniferous of the united states previous interpretations are mainly misleading and contradictory primarily because of the assumption that the brown color and exceptional cellular and subcellular preservation typical of american coal balls imply chemical preservation of cellulose and lignin the primary components of peat xylem tissue from a medullosan seed fern contained in a coal ball and the coal attached to the coal ball from the calhoun coal bed mattoon formation illinois was analyzed by elemental petrographic and nuclear magnetic resonance nmr techniques to determine the degree of coalification the nmr and elemental data indicate the lack of cellulose and lignin and a probable rank of high volatile c bituminous coal these data corroborate data for a coal ball from the herrin no 6 coal bed carbondale formation middle pennsylvanian and support our hypothesis that the organic matter in coal balls of the pennsylvanian strata of the united states is coalified to about the same degree as the surrounding coal data presented show a range of lower reflectances for xylem tissue and vitrinite in the analyzed coal balls compared with vitrinite in the attached coal the data reported indicate that physical preservation of organic matter in coal balls does not imply chemical preservation also our study supports the hypothesis that compactional static load pressure is not a prerequisite for coalification up to a rank of high volatile c bituminous coal a whole rock analysis of the calhoun coal ball indicates a similarity to other carbonate coal balls from the united states it consists primarily of calcium carbonate and 1 2 organic matter silica and alumina together make up less than 0 5 indicating the lack of minerals such as quartz and clays

collapse and reconstruction of monowai submarine volcano kermadec arc 1998 2004 monowai submarine volcano is one of the three most historically active volcanoes of the kermadec arc repeat multibeam surveys of monowai cone from september 1998 and september 2004 and t wave data recorded by the reseau sismique polynesien network for the same period document the collapse and subsequent regrowth of the cone within this 6 a period grid differencing of the two bathymetric data sets acquired 6 a apart reveals that a landslide 2230 m long occurred between the surveys within which a postcollapse cone and talus ridge 0 023 km3 in volume subsequently formed the volume of this collapse minus postcollapse construction is 0 085 km3 we interpret an unusual strong amplitude t wave event on 24 may 2002 as recording hot landsliding where the 100 to 160 m thick collapse has unroofed the uppermost parts of the vent conduit with the subsequent explosive interaction and cooling of hot magma and volcaniclastic rubble with ambient seawater this interpretation is consistent with the lack of emergent events sharp onset and large amplitude of the 24 may 2002 t waves the subsequent 2500 t wave events between november 2002 and september 2004 occurred in swarms with emerging and waning activity and with typical explosive volcanic acoustic signatures which are interpreted as recording the regrowth of an 90 m high cone back to a near 1998 elevation at an average rate of 47 m a 1 this study provides 1 a lower bound for frequency magnitude relationships of landsliding for submarine arc volcanoes and 2 estimates of 0 013 km3 a 1 of submarine cone growth during eruptive cycles

active geothermal systems with entrained seawater as modern analogs for transitional volcanic hosted massive sulfide and continental magmato hydrothermal mineralization the example of milos island greece the paradigm for low sulphidation ls volcanic arc associated mineralization is the active geothermal systems located along the taupo volcanic zone e g broadlands however this analogue is inapt where fluid salinities are consistently in excess of 3 5 wt nacl ls mineralization on milos aegean arc records high paleofluid salinities the d and 18o data do not exemplify 18o shifted meteoric waters typical of terrestrial geothermal systems nor is a submarine origin indicated stable isotope data show mixing between meteoric seawater and volcanic arc gases strontium isotope data are comparable to a nearby active seawater entrained geothermal system these are features seen in hydrothermal systems associated with emergent volcanoes for the milos ls mineralization high salinity fluids show it cannot be explained by a broadlands type model the absence of saliferous sequences and significant intrusive rocks preclude these as salinity sources the similarities between paleo and active systems in terms of salinity d 18o and strontium isotope systematics strongly suggest that seawater is the main source for na and cl we suggest geothermal systems containing seawater associated with emergent volcanoes are an alternative analogue for ls epithermal mineralization furthermore they bridge the gap between submarine and large scale terrestrial geothermal systems the modern analogues for vhms and epithermal mineralisation in the scheme of intrusion centered hydrothermal mineralization

the transition from porphyry to epithermal style gold mineralization at ladolam lihir island papua new guinea a reconnaissance study the exceptionally large gold resource at ladolam 1 300 metric tons of gold lihir island resulted from the transition of an early stage low grade porphyry gold system to a low sulfidation epithermal gold event this transition was probably triggered by rapid decompression during the partial slope failure of luise stratovolcano and accompanied by the ingress of seawater the original porphyry stage is indicated by remnant hydrothermal breccia clasts of strongly biotite magnetite altered monzodiorite with disseminated pyrite chalcopyrite and poorly developed pyrite quartz stockwork veins the breccias are overprinted by biotite magnetite alteration and their matrix is strongly mineralized with disseminated auriferous pyrite the breccias are cut by late stage epithermal quartz chalcedony illite adularia pyrite veins and associated illite adularia alteration that locally contain bonanza gold grades of up to 120 g t isotope data suggest a magmatic source of sulfur in the gold bearing fluids at ladolam electronic supplementary material to this paper can be obtained by using the springer link server located at http dx doi org 10 1007 s00126 001 0230 y

package fluids 1 computer programs for analysis of fluid inclusion data and for modelling bulk fluid properties the computer package fluids contains five sets of computer programs written in c for the calculation of fluid properties both model fluids and data from fluid inclusions can be analysed in the programs bulk density molar volume and composition of fluid inclusions are calculated with the program bulk which uses microthermometric data micro raman spectroscopic data cation ratios and volume fraction estimations as input the program offers a broad variety of equations of state which are selected according to the fluid system or the temperature and pressure conditions of interest the isochores that correspond to the output or test v x properties of fluid inclusions are calculated by the program isoc in calculating the isochores this program takes account of the compressibility and expansion of selected host minerals the program test allows different equations of state to be compared directly with experimental data thereby facilitating selection of the most adequate model in the programs bulk and isoc loner is a group of programs that handle individual equations of state eos for all fluid systems presented in the programs bulk and isoc aqso is a group of programs that allows purely empirical modelling of electrolyte bearing aqueous solutions henry s law for dilute gas bearing aqueous solutions and osmotic coefficients for dilute electrolyte bearing aqueous solutions the programs are available on the university of leoben web site at http www unileoben ac at buero62 minpet ronald

drilling shallow water massive sulfides at the palinuro volcanic complex aeolian island arc italy a subseafloor replacement style barite and sulfide occurrence was drilled in shallow waters at the palinuro volcanic complex the northernmost aeolian arc volcano in the tyrrhenian sea italy using a lander type drilling device 11 successful drill holes yielded a total of 13 5 m of core from a sediment filled depression located at a water depth of 630 to 650 m the longest continuous drill core recovered consists of 4 84 m of massive to semimassive barite and sulfides with abundant late native sulfur overprint seafloor observations suggest that the hydrothermal system associated with the formation of the subseafloor barite and sulfide ore zone is still active although black smoker activity does not occur on the seafloor the recovered drill core shows that the subseafloor deposit is zoned with depth the top of the mineralized zone is comprised of a variably silicified vuggy barite sulfide facies that shows notable polymetallic metal enrichment while the deeper portion of the mineralized zone is dominated by massive pyrite having distinctly lower base and precious metal grades metal zonation of the barite and sulfide deposit is related to the evolution of the hydrothermal fluids in space and time the barite cap and the massive pyrite present in the deeper portion of the mineralized zone appear to have formed early in the paragenesis during the main stage of the mineralization the barite cap was brecciated and cemented by a polymetallic assemblage of barite and pyrite with minor chalcopyrite and tetrahedrite trace famatinite and rare cinnabar lower temperature precipitates formed during the main stage of mineralization include sphalerite galena pyrite opal a and barite which are associated with traces of pb sb as sulfosalts such as bournonite seligmannite or semseyite a distinct mineral assemblage of fine grained anhedral enargite hypogene covellite chalcopyrite and galena is commonly associated with colloform sphalerite galena and pyrite as a late phase of this main stage colloform pyrite and marcasite are the last sulfides formed in the paragenetic sequence the deposit is interpreted to have formed from fluids having an intermediate sulfidation state although excursions to high and very high sulfidation states are indicated by the presence of abundant enargite and hypogene covellite laser ablation and conventional sulfur isotope analyses show that pyrite formed close to the seafloor within the zone of polymetallic metal enrichment has a variable sulfur isotope composition 34s 39 to 3 whereas a more narrow range is observed in the massive pyrite at depth 34s 10 to 0 similar variations were also documented for the late native sulfur overprint overall the negative sulfur isotope ratios at depth the intermediate to very high sulfidation conditions during mineralization and the abundance of native sulfur suggest contributions of magmatic volatiles to the mineralizing fluids from a degassing magma chamber at depth biological processes are interpreted to have played a major role during late stages of ore formation the combination of a subseafloor replacement deposit with a massive to semimassive barite cap rock overlying massive pyrite the intermediate to high sulfidation characteristics and the strong biological influence on the late stages of mineralization are distinct from other modern seafloor massive sulfide deposits and represents a style of submarine mineralization not previously recognized in a modern volcanic arc environment the barite and sulfide occurrence at palinuro shares many characteristics with porphyry related base metal veins and intermediate sulfidation epithermal deposits suggesting that metallogenic processes associated with arc related magmatic hydrothermal systems are not restricted to the subaerial environment

depositional setting and paleobotany of permian and triassic permineralized peat from the central transantarctic mountains antarctica abstract silicified peat is known from two sites in the central transantarctic mountains both are within a 2 km thick permo triassic sandstone shale sequence that was deposited by braided streams in a rapidly subsiding foreland basin along the paleo pacific margin of antarctica upper permian permineralized peat occurs as scattered boulders just above a channel form sandstone in the upper part of the buckley formation on skaar ridge overlooking the beardmore glacier these boulders are erosional remnants of fine grained deposits that accumulated in shallow lakes or swamps on a flood plain at fremouw peak the peat occurs near the top of the fremouw formation in strata that are probably middle to late triassic in age the peat consists of large blocks that were rafted into a sandy braided stream channel during a flood and then stranded and buried as flood waters receded both sites are characterized by exceptionally well preserved plant material although the composition and diversity of the two floras are very different permineralization apparently took place rapidly and was enhanced by the dissolution of siliceous volcanic detritus that is abundant in both formations

growth and mass wasting of volcanic centers in the northern south sandwich arc south atlantic revealed by new multibeam mapping new multibeam swath bathymetric sonar data acquired using an em120 system on the rrs james clark ross supplemented by sub bottom profiling reveals the underwater morphology of a not vert similar 12 000 km2 area in the northern part of the mainly submarine south sandwich volcanic arc the new data extend between 55 45 s and 57 20 s and include protector shoal and the areas around zavodovski visokoi and the candlemas islands groups each of these areas is a discrete volcanic center the entirely submarine protector shoal area close to the northern limit of the arc forms a 55 km long east west trending seamount chain that is at least partly of silicic composition the seamounts are comparable to small subaerial stratovolcanoes in size with volumes up to 83 km3 indicating that they are the product of multiple eruptions over extended periods zavodovski visokoi and the candlemas island group are the summits of three 3 3 5 km high volcanic edifices the bathymetric data show evidence for relationships between constructional volcanic features including migrating volcanic centers structurally controlled constructional ridges satellite lava flows and domes and mass wasting of the edifices mass wasting takes place mainly by strong erosion at sea level and dispersal of this material along chutes probably as turbidity currents and other mass flows that deposit in extensive sediment wave fields large scale mass wasting structures include movement of unconsolidated debris in slides slumps and debris avalanches volcanism is migrating westward relative to the underlying plate and major volcanoes are asymmetrical being steep with abundant recent volcanism on their western flanks and gently sloping with extinct eroded volcanic sequences to their east this is consistent with the calculated rate of subduction erosion of the fore arc

organic matter in a coal ball peat or coal chemical analyses of morphologically preserved organic matter in a carboniferous coal ball reveal that the material is coalified to a rank approximately equal to that of the surrounding coal hence the plant tissues in the coal ball were chemically altered by coalification processes and were not preserved as peat

the effects of early diagenesis on the chemical and stable carbon isotopic composition of wood abstract studies of modern and ancient buried wood show that there is a linear correlation between carbohydrate content and the stable carbon isotope composition as carbohydrates are preferentially degraded during early diagenesis as the carbohydrate content decreases the 13 c value of the degraded wood decreases 1 to 2 per mil approaching the value of the residual lignin these results indicate that carbohydrate degradation products are lost and not incorporated into the aromatic structure as lignin is selectively preserved during early diagenesis of wood these results also indicate that attempts to quantify terrestrial inputs to modern sedimentary organic matter based on 13 c values should consider the possibility of a 1 to 2 per mil decrease in the 13 c value of degraded wood

origin of the eskay creek precious metal rich volcanogenic massive sulfide deposit fluid inclusion and stable isotope evidence the eskay creek deposit is an unusual polymetallic au ag rich volcanogenic sulfide sulfosalt deposit located in the iskut river area of northwestern british columbia canada economic concentrations of precious and base metals are contained in the 21 zone which is divided into a number of subzones as of december 31 1998 total production and proven probable reserves are 1 9 million tons mt at 60 2 g t au 2 652 g t ag 3 2 percent pb 5 2 percent zn and 0 7 percent cu the 21b zone which contains the bulk of the reserves began production in 1995 the mineralization occurs mainly as well preserved stratiform clastic beds of sulfide sulfosalt debris and also as discordant footwall quartz sulfide veins the hydrothermal system that formed the eskay deposit was low temperature

shallow submarine epithermal pb zn cu au ag te mineralization on western milos island aegean volcanic arc greece mineralogical geological and geochemical constraints abstract milos island contains several epithermal deposits e g profitis ilias chondro vouno pb zn ag au te cu triades galana agathia kondaros pb zn ag bi w mo cu au and katsimoutis kondaros vani pb zn ag mn of late pliocene to early pleistocene age these deposits are hosted in calc alkaline volcanic rocks emplaced as a result of three successive magma pulses in an emergent volcanic edifice submarine rhyolitic to rhyodacitic cryptodomes at ca 2 7 ma profitis ilias chondro vouno submarine to subaerial andesite to dacite domes at ca 2 2 to 1 5 ma triades galana kondaros katsimouti vani hydrothermal alteration of the volcanic rocks includes advanced argillic both hypogene and steam heated argillic phyllic adularia sericite and propylitic types in the northern sector triades galana agathia kondaros initial magma degassing derived from andesitic dacitic intrusives along ne sw to e w trending faults resulted in the development of pre ore hypogene advanced argillic alteration dickite alunite diaspore pyrophyllite halite and pyrite in a submarine environment mineralogical data indicate common features among the profitis ilias chondro vouno kondaros katsimoutis vani and triades galana mineralized centers all of which are characterized by the presence of galena fe poor sphalerite and chalcopyrite as well as abundant barite adularia sericite and to a lesser extent calcite which are typical of intermediate sulfidation epithermal type deposits locally at triades galana and kondaros agathia high sulfidation conditions prevailed as suggested by the presence of coexisting enargite and covellite the high silver and gold content of the western milos deposits is derived from ag bearing sulfosalts polybasite pearceite pyrargyrite freibergite and tellurides gold at profitis ilias both as native gold and silver gold tellurides is present in base metal precipitates within multicomponent blebs which recrystallized to form hessite petzite altaite coloradoite and native gold mineralogical evidence e g microchimney structures copper sulfides widespread occurrence of barite aragonite suggests that precious metal mineralization in western milos mineralization formed in a submarine setting we present information on the surface distribution of au ag cu pb zn as sb hg mo bi w and cd at western milos gold is enriched at profitis ilias chondro vouno deposits and to a lesser extent at triades galana arsenic is absent from the southern sector but shows elevated concentrations together with molybdenum bismuth and tungsten at the northern sector triades galana vani deposits the differences in precious and base metal abundances may be related to the depths at which the deposits are exposed and or different sources of magma the metal signatures of the triades galana and agathia kondaros katsimouti vani mo bi w as hg ag au occurrences compared to profitis ilias te au ag reflect different sources of magma dacite rhyodacite for profitis ilias andesite dacite for triades galana and dacite for kondaros katsimoutis the enrichment of te mo w and bi in the deposits is a strong indication of a direct magmatic contribution of these metals at western milos precious and base metal vein mineralization was deposited during episodic injection of magmatic volatiles and dilution of the hydrothermal fluids by seawater the mineralization represents seafloor sub seafloor precipitation of sulfides that formed in stockwork zones base and precious metal mineralization formed from intermediate to high sulfidation state fluids and mostly under boiling conditions as indicated by the widespread occurrence of adularia associated with metallic mineralization we speculate that the widespread occurrence of boiling and the shallow depth of the precious and base metal emplacement prevented the formation of seafloor massive sulfides

volcaniclastic processes on modern submarine arc stratovolcanoes sidescan and photographic evidence from the rumble iv and v volcanoes southern kermadec arc sw pacific abstract studies of volcaniclastic processes on modern submarine arc stratovolcanoes are rare facies models of submarine volcanism and associated volcaniclastic deposits have to date emphasized general and or regional processes two andesite alkali basaltic volcanoes rumble iv and v volcanoes from the southern kermadec arc are mapped with swath bathymetry and sidescan imagery and photographic data to characterise volcaniclastic processes on these modern submarine arc stratovolcanoes and their interaction with ambient marine processes the principal observation from the rumble iv and v data is the fine scale spatial variability in the distribution of effusive lavas various volcaniclastic deposits and hemipelagic pelagic sediments mass movement of volcaniclastic deposits is common and includes 1 epiclastic debris flows 2 pillow breccia talus deposition penecontemporaneous with lava eruption 3 traction particulate gravity flows and possibly 4 sector collapse epiclastic redeposition is inferred to be mobilised by episodic but frequent localised small volume flows which largely redeposit debris on the edifice winnowed and rippled volcaniclastic sediment indicates bottom current activity is common but localised over the entire height of both volcanoes down to a water depth of 2200 m these currents also possibly entrain detritus for subsequent mobilisation by particulate gravity flows irregular and ragged spatter agglutinates on rumble iv interpreted as evidence of lava fountaining and wellsorted fines poor scoriaceous material on rumble v interpreted as evidence of explosive eruption indicate the transition between effusive and explosive volcanism is between 650 and 700 m water depth other southern kermadec volcanoes e g tangaroa have scoriaceous detritus at 960 970 m water depth positions of these effusive explosive transition zones are likely to oscillate up and down the volcano during glacioeustatic fluctuations

constraints on water depth of massive sulfide formation evidence from modern seafloor hydrothermal systems in arc related settings the results of three decades of seafloor research provide the most reliable information on the importance of water depth in massive sulfide formation available data from over 130 occurrences show that water depths of seafloor vent sites vary with plate tectonic setting and the regional magmatic and volcanic environment the shallowest hydrothermal systems in subduction related settings are hosted by arc volcanoes these shallow vent sites have a number of features in common with subaerial epithermal systems massive sulfide occurrences in arc related rifts the most likely setting for many ancient analogs are generally restricted to water depths from 700 to 2 000 m with rifts developing within old arc crust at the deeper end of this range back arc spreading centers proximal to arcs host massive sulfide deposits at depths of 1 500 to 2 000 m the deepest hydrothermal systems occur along mature back arc spreading centers distal to volcanic arcs where water depths range from 2 000 to 3 700 m these deeper vent sites probably represent the best modern analogues of ophiolite hosted massive sulfide deposits boiling of the hydrothermal fluids is common at volcanic arcs and in arc related rifts in these environments elevated magmatic gas contents of the hydrothermal fluids can contribute to the widespread occurrence of phase separation and associated gas loss by contrast the high ambient pressures in deep marine hydrothermal systems along mature back arc spreading centers prevent fluids from boiling during their ascent to the seafloor boiling controls the maximum temperature at which hydrothermal fluids discharge at the seafloor and therefore influences the metal content of seafloor sulfide deposits copper rich massive sulfides typically occur at water depths exceeding 1 000 m whereas zn and pb rich occurrences may form at any water depth boiling can be an important control on ag and au grades but is not the only factor controlling precious metal enrichment in massive sulfides shallow marine hot spring deposits can be highly enriched in trace metals such as as hg and sb submarine volcanic arc and back arc settings are geologically complex and significant variations in water depth can occur over short distances paleoenvironmental reconstruction of these environments in ancient volcanic terranes is hampered by the lack of unequivocal volcanological or sedimentological criteria that indicate water depth the relationships established here using modern seafloor observations provide important constraints on the paleoenvironmental setting of ancient volcanic hosted massive sulfide deposits

280 m y old fossil starch reveals early plant animal mutualism starch is a major component in the human diet and the acquisition of starch rich food sources is considered a pivotal step in the biological and cultural evolution of humankind however the potential role of starch as an energy vector in paleo ecosystems has never been addressed obviously due to the lack of tangible records of prequaternary starch grains here we describe similar to 280 m y old lycopsid megaspores from permian forest swamp deposits in north china that bear caps of granular material size shape and surface structures as well as chemical and optical properties of these grains show that these caps are masses of compound storage starch this is by far the oldest unequivocal record of fossil starch known to date deposition outside the actual megaspore container makes it unlikely that these starches were used for embryo nutrition moreover ultrathin sections of the megaspores indicate that they may have been produced after the megaspores were fertilized by analogy to the elaiosomes on seeds of zoochorous plants today we suggest that these starch caps were used to attract and reward animals possibly land arthropods or snails for megaspore dispersal this study offers a rare glimpse into early stages of plant animal co evolution in permian swamp forest ecosystems

mass wasting events and their impact on the formation and preservation of submarine ore deposits abstract mass wasting and landform modifying events have a profound impact on hydrothermal processes in terrestrial environments mass wasting events in submarine settings also modify hydrothermal systems and their associated mineralisation we present evidence of a dynamic environment impacting on ore formation at the historically exploited pb zn ag mineralisation of triades milos island greece formed in a submarine setting galena sphalerite veins and barite quartz gangue precipitated in the near subsurface or after exhalation of boiling hydrothermal fluids field evidence indicates that mineralisation was extensively reworked by debris flow events during formation the mineral paragenetic sequence is consistent with a pb zn ag massive sulphide system and analogous to the early stages of a kuroko type deposit but triades lacks massive sulphide bodies we suggest that mass wasting events literally truncated the developing mineral deposit as it formed on the seafloor destroying massive sulphide bodies and limiting the development of the ore mineral assemblages mass wasting processes in volcanogenic massive sulphide systems are ore destructive with little opportunity for telescoping unlike terrestrial equivalents shallow marine systems in terrains subject to mass wasting may have low preservation potential or may be classified as epithermal like vein systems rather than stockwork portions of massive sulphide deposits

compression cuticle relationship of seed ferns insights from liquid solid states ftir late palaeozoic early mesozoic canada spain argentina abstract cuticles have been macerated from suitably preserved compressed fossil foliage by schulze s process for the past 150 years whereas the physical biochemical relationship between the coalified layer with preserved cuticle as a unit has hardly been investigated although they provide complementary information this relationship is conceptualized by an analogue model of the anatomy of an extant leaf vitrinite mesophyll cuticle biomacropolymer compression alkaline solutions from schulze s process as a proxy for the vitrinite are studied by means of liquid solid states fourier transform infrared spectroscopy ftir in addition cuticle free coalified layers and fossilized cuticles of seed ferns mainly from canada spain and argentina of late pennsylvanian late triassic age are included in the study sample infrared data of cuticle and alkaline solutions differ which is primarily contingent on the mesophyll biomacropolymer characteristics the compression records two pathways of organic matter transformation one is the vitrinized component that reflects the diagenetic post diagenetic coalification history parallel with the evolution of the associated coal seam the other is the cuticle that reflects the sum total of evolutionary pathway of the biomacropolymer its monomeric or polymeric fragmentation though factors promoting preservation include entombing clay minerals and lower ph conditions caution is advised when interpreting liquid state based ftir data as some ir signals may have resulted from the interaction of schulze s process with the cuticular biochemistry a biochemical study course for taphonomy is suggested as fossilized cuticles cuticle free coalified layers and compressions are responses to shared physicogeochemical factors

an upper pliocene coarse pumice breccia generated by a shallow submarine explosive eruption milos greece the filakopi pumice breccia fpb is a very well exposed pliocene volcaniclastic unit on milos greece and has a minimum bulk volume of 1 km3 it consists of three main units a basal lithic breccia 4 8 m mainly composed of angular to subangular andesitic and dacitic clasts up to 2 6 m in diameter b very thickly bedded poorly sorted pumice breccia 16 17 m and c very thick reversely graded grain supported coarse pumice breccia 6 5 20 m at the top the depositional setting is well constrained as shallow marine up to a few hundred metres by overlying fossiliferous and bioturbated mudstone this large volume of fine pumice clasts is interpreted to be the product of an explosive eruption from a submarine vent because 1 pumice clasts are the dominant component 2 the coarse pumice clasts 64 mm have complete quenched margins 3 very large 1 m pumice clasts are common 4 overall the formation shows good hydraulic sorting and 5 a significant volume of ash was deposited together with the coarsest pyroclasts

nuclear magnetic resonance studies of ancient buried wood i observations on the origin of coal to the brown coal stage various wood fragments buried in sediments under anaerobic conditions for from 450 yr to approximately 8 myr have been examined by solid state 13c nuclear magnetic resonance cellulose and other carbohydrates the major components of holocene wood have been shown to be gradually hydrolyzed or otherwise lost under the conditions of burial lignin structures however are preserved relatively unchanged and become concentrated by difference as the carbohydrates disappear thus a fragment of coalified wood isolated from a miocene brown coal was found to be still composed of approximately 75 lignin and 25 cellulose on the basis of our observations we suggest that coalification of woody tissue progresses directly from lignin to coal and that such coalification may be retarded until most of the cellulose disappears