permafrost and climate in europe monitoring and modelling thermal geomorphological and geotechnical responses we present a review of the changing state of european permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of svalbard and the discontinuous high altitude mountain permafrost of iceland fennoscandia and the alps the paper focuses on methodological developments and data collection over the last decade or so including research associated with the continent scale network of instrumented permafrost boreholes established between 1998 and 2001 under the european union pace project data indicate recent warming trends with greatest warming at higher latitudes equally important are the impacts of shorter term extreme climatic events most immediately reflected in changes in active layer thickness a large number of complex variables including altitude topography insolation and snow distribution determine permafrost temperatures the development of regionally calibrated empirical statistical models and physically based process oriented models is described and it is shown that though more complex and data dependent process oriented approaches are better suited to estimating transient effects of climate change in complex mountain topography mapping and characterisation of permafrost depth and distribution requires integrated multiple geophysical approaches and recent advances are discussed we report on recent research into ground ice formation including ice segregation within bedrock and vein ice formation within ice wedge systems the potential impacts of climate change on rock weathering permafrost creep landslides rock falls debris flows and slow mass movements are also discussed recent engineering responses to the potentially damaging effects of climate warming are outlined and risk assessment strategies to minimise geological hazards are described we conclude that forecasting changes in hazard occurrence magnitude and frequency is likely to depend on process based modelling demanding improved understanding of geomorphological process response systems and their impacts on human activity

application of uav bvlos remote sensing data for multi faceted analysis of antarctic ecosystem abstract a photogrammetric flight was performed in december 2016 as bvlos beyond visual line of sight operation over penguin island south shetland islands western antarctica images were taken by the pw zoom fixed wing uav equipped with a digital slr canon 700d camera the flight was performed at 550 m asl and covered a total distance of 231 58 km the plane take off and landing site was near the h arctowski polish antarctic station arctowski on king george island south shetlands the main aim of the mission was to collect environmental data to estimate the size of penguin and pinniped breeding populations and to map vegetation cover and landforms the plane returned to arctowski with 1630 images of penguin island with the ground sample distance gsd lower than 0 07 m the analysis of developed ortophoto allowed us to locate and identify individuals of two penguin species adelie and chinstrap and individuals of two species of pinnipeds southern elephant seal and weddell seal three types of tundra communities were mapped together with numerous landforms such as volcanic mass movement fluvial coastal and aeolian ones the uav bvlos photogrammetric operation proved to be very robust in gathering valuable qualitative and quantitative data necessary for monitoring distant and isolated polar environments

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

new understandings of ni mo mineralization in early cambrian black shales of south china constraints from variations in organic matter in metallic and non metallic intervals abstract the well known ni mo ores hosted in early cambrian black shales of south china are one of the research highlights in economic geology for the past few decades however their origin is complex and still debated here based on a case study in the huangjiawan ore of zunyi city guizhou province we generate several new understandings regarding ni mo mineralization through a comparative investigation of organic matter in metallic and non metallic stratigraphic intervals including abundance type maturity and relationship to mineralization we find new direct evidence for biotic impacts on mineralization organic matter and rhodophyte cystocarps red algae in particular may be significantly correlated to mineralization as it accumulates mineralized ni and mo however this organic material as well as disseminated and amorphous organic matters is not the sole and predominant factor controlling mineralization as implied from the nonlinear correlation between organic matter abundance maturation and mineralization other fluid sources e g hydrothermal and or seawater also contribute to mineralization which may be influenced by hydrothermal activity ni and mo may have mineralized independently as suggested by their differential accumulation in different structures of the cystocarps different relationships between organic matter abundance and thermal maturation and mineralized element concentration as well as the large variation in element accumulation coefficients the history of mineralization is complex as ni and mo may be or not be deposited together during the same stage of mineralization these results might also have broader implications for understanding the origin of sediment hosted ores worldwide

electrical resistivity structure of the upper mantle beneath northeastern china implications for rheology and the mechanism of craton destruction abstract the north china craton ncc and central asian orogen belt caob in northeastern china experienced a range of tectonic events during the phanerozoic dominated by lithospheric thinning of the eastern ncc in the late mesozoic and cenozoic in order to better understand the tectonic evolution of the ncc and the caob new broadband and long period magnetotelluric data were collected along a north west to south east trending profile that extended from the caob across the yanshan belt the tanlu fault zone to the liaodong peninsula a two dimensional 2 d resistivity model was derived from inversion of the transverse electric mode transverse magnetic mode and vertical magnetic field data in the crust of the caob the resistivity model shows a northwest dipping low resistivity zone beneath the solonker suture that is identified as the suture zone formed by the collision between the siberian and north china cratons the upper mantle of the caob is characterized by moderate resistivity values 300 1000 m that are best explained by the presence of hydrogen dissolved in olivine the water concentration of the caob mantle is comparable to values reported for the asthenosphere and cratons that have been significantly hydrated the ncc upper mantle is generally lower in resistivity than the caob upper mantle and a zone of lower resistivity is observed in the upper mantle at the southeast end of the profile beneath the ncc superimposed on this southeast decrease in upper mantle resistivity three low resistivity zones were imaged 1 below the xilamulun fault 2 close to the north south gravity lineament and 3 between the northern yanshan belt and tanlu fault zone the low resistivities can be explained as regions of partial melts or fluids perhaps caused by asthenospheric upwelling together with seismic imaging results and geochemical data the resistivity model shows that the modification of the lithosphere associated with craton destruction has occurred in a spatially non uniform manner in the region of the ncc investigated in this study

manganese deposits of the devonian magnitogorsk palaeovolcanic belt southern urals russia abstract recent studies provide an overview on hydrothermal volcaniclastic sedimentary manganese deposits from the magnitigorsk palaeovolcanic belt in southern urals russia 100 deposits this report presents data on the structures of ore bodies chemical composition and mineralogy of manganese ores these deposits are divided into two types with different ore bearing band structures chemical and mineral ore compositions and ore component accumulation conditions manganese ores of the type 1 deposit are associated with jasperites ores from type 2 deposits are localised within thin banded jaspers type 1 deposits are thought to form during hydrothermal activity in areas where hydrothermal fluids leak into the seafloor type 2 deposits are formed within a closed basin as hydrothermal activity decreases away from hydrothermal vents and typically contain a greater volcaniclastic contribution manganese ores comprised more than 70 mineral types and form three groups of mineral assemblages a minerals formed during low grade regional metamorphism t 200 260 c p 2 3 kbar that compose the main part of ore bodies b mineral assemblages in segregatic and metasomatic veins filling late stage tectonic fractures and c an assemblage of subsurface supergene minerals most of these minerals which total approximately 38 minerals are metamorphic silicates the formation of metamorphic mineral assemblages is controlled by the presence of organic material om in primary sediments the conditions under which type 1 deposits formed favour the accumulation of om the metamorphism of these sediments is responsible for the formation of oxide carbonate silicate reduced ores which consist of mn silicates and carbonates such as tephroite rhodonite caryopilite and rhodochrosite andradite quartz hematite and hausmannite insignificant preserved quantities of om were found in type 2 deposits during the metamorphic alteration of these sediments oxide silicate oxidised ores were formed with the dominance of braunite

unveiling the provenance of sediments in the moraine complex of aldegonda glacier svalbard after glacial retreat using radionuclides and elemental fingerprints abstract in the changing glacierized areas of the maritime arctic region fluxes of sediments are of high intensity during the arctic melting season on the western spitsbergen island around gronfjord several glaciers have declined rapidly over the last century the aldegonda glacier has retreated about 2 km since 1911 when the glacier tongue reached the seashore which lead to new exposed surfaces in the proglacial area supplying sediments to the fjord during the arctic summer we explored if the geochemical signature of sediments can be used to discriminate sediment provenance in proglacial environments during different stages of the melting season to this purpose a sampling campaign was undertaken in july 2015 in the aldegonda glacier area to obtain 24 composite surface samples of moraine materials and sediments at the glacier surface and 12 sediment mixtures fingerprinting techniques were applied to determine the sediment provenance and tracers were selected using a novel conservative index and consensus ranking method fingerpro model identified bottom moraines as predominant source in all cases 74 recent moraines amounted to 15 and sediment on ice contributed 11 radionuclide signatures were of great value to identify sediment provenance and 137cs and 210pbex were among the most selected tracers variations in source contributions depended on the location and type of the sediment mixtures differences in source contributions also varied temporarily suggesting different sediment mobilization processes during snow and ice melt snow and ice melt are the main drivers of sediment mobilization contributed from moraines during summer moreover sediments accumulated on the glacier surface including cryoconite deliver radionuclides and heavy metals associated to fine particles that have an impact on terrestrial and sea arctic ecosystems such deleterious impact could be one main effect of climate change on glacierized environments worldwide

systematics of chlorite alteration at the phelps dodge massive sulfide deposit matagami quebec hydrothermal alteration at the phelps dodge archcan volcanogenic massive sulfide deposit has converted rhyodacite and rhyolite footwall rocks into the following mineral assemblages quartz chlorite albite epidote or sericite quartz chlorite or sericite chlorite or sericite and chlorite talc or stilpnomelane alteration at constant al was initiated by hydration addition of fe mg silicification and leaching of ca na which produced al saturated chlorites with a wide range of fe fe mg ratios within the assemblage quartz chlorite albite epidote or sericite with continued addition of fe and less mg combined with extensive leaching of quartz the chlorite became al undersaturated quartz chlorite talc assemblage and ultimately formed a rock composed essentially of chlorite the chlorite talc or stilpnomelane assemblage is stable in late crosscutting veinlets and in the ore zone chlorites in the si al mg fe system form a rectangular solid solution plane with limited substitution of al for si and extensive substitution of fe for mg in si al space the solid solution plane is outlined by al saturation presence of other al rich mineral and al undersaturation presence of al poor or al free mineral boundaries al iv substitution for si in the chlorites increases from 2 3 to 3 01 formula units based on 8 si al iv with fe fe mg whereas al iv occupancy decreases from 2 88 to 2 65 the valence charge balance is compensated by octahedral site vacancies or by the conversion of fe super 2 to fe super 3 the al iv content of chlorite also increases with temperature chlorites on the al saturated boundary of the solid solution field form a potentially useful geothermometer t degrees c 106 al iv 18 al iv is corrected for changes with the fe fe mg ratio as al iv corrected al iv 0 7 fe fe mg the fe fe mg ratios of bulk rock and contained chlorite correlate well birefringence colors of the chlorite change from green to brown violet and berlin blue as fe fe mg changes from 0 18 to 0 64 the fe fe mg variation apparently depends largely on the proportions of mg rich seawater and fe rich hydrothermal fluid in the altering brine

holocene glacial history of antarctica and the sub antarctic islands abstract a history of holocene glaciation in the antarctic and sub antarctic affords insight into questions concerning present and future ice sheet and mountain glacier behavior and global climate and sea level change existing records permit broad correlation of holocene ice fluctuations within the region in several areas ice extent was less than at present in mid holocene time an important exception to this is the west antarctic ice sheet which has undergone continued recession throughout the holocene probably in response to internal dynamics the first neoglacial ice advances occurred at 5 0 ka although some sites e g western ross sea lack firm evidence for glacial expansion at that time glaciers in all areas underwent renewed growth in the past millennium and most have subsequently undergone recession in the past 50 years ranging from near catastrophic in parts of the antarctic peninsula to minor in the western ross sea region and sections of east antarctica this magnitude difference likely reflects the much greater warming that is taking place in the antarctic peninsula region today as compared to east antarctica

a proxy for snow cover and winter ground surface cooling mapping usnea sp communities using high resolution remote sensing imagery maritime antarctica usnea sp formations show a spatial distribution coinciding with wind exposed locations on rock knobs or sedimentary bodies while they are commonly absent from concave sites field collection of georeferenced ground truthing data in the meseta norte fildes peninsula maritime antarctica and the application of supervised classification techniques over a summer high resolution quickbird satellite scene showed excellent classification accuracy for the different landcover types the results show that usnea formation distribution maps are a viable proxy for areas with less snow during the cold season such an approach provides input for permafrost and active layer modelling since snow acts as a critical control on ground surface heat balance since snow mapping is extremely difficult in maritime antarctica our tested approach provides important added value for empirical statistical modelling of permafrost distribution

micromorphology and microchemistry of selected cryosols from maritime antarctica little information is available on the microstructure of cryosols from maritime antarctica and the present study characterizes the main soil types commonly found in ice free areas of admiralty bay king george island four pedons were selected for micromorphological and microprobe analysis the type of microstructure observed in the soils is strongly influenced by the lithological composition and arrangement with a high proportion of primary minerals in all particle fractions the oxidation of sulphides is the most important pedogenetic process in acid sulphate soils from maritime antarctica and results in intense chemical weathering of minerals and formation of na jarosite amorphous fe oxides and kaolinite jarosite forms illuvial coating within cryodesiccation fractures and is associated with large amounts of amorphous fe minerals that possess a high p adsorption capacity in ornithogenic soils the phosphatization process enhances soil acidity and chemical alteration of the substrate and is the main soil forming process in ornithogenic soils p rich solutions penetrate cryodesiccation fractures and cleavage planes in large clasts and preferentially react with volcanic glass soil reaction with p rich leachates leads to the progressive displacement of si from rock minerals coupled with reacting of p with al fe k and mg to form various amorphous and crystalline p forms cryoclastic weathering and cryoturbation result in high levels of fine p rich aggregates down the profile chemical weathering is more pronounced in maritime antarctica than previously thought especially for acid sulphate and ornithogenic soils the utilization of micromorphological and microchemical techniques proved to be extremely useful for a better understanding of pedogenesis in these poorly known antarctic soils

fossilized fungi in subseafloor eocene basalts the deep biosphere of subseafloor basalts is thought to consist of mainly prokaryotes bacteria and archaea here we report fossilized filamentous microorganisms from subseafloor basalts interpreted as fossilized fungal hyphae probably dikarya rather than fossilized prokaryotes the basalts were collected during the ocean drilling program leg 197 at the emperor seamounts north pacific ocean and the fossilized fungi are observed in carbonate filled veins and vesicles in samples that represent a depth of 150 m below the seafloor three dimensional visualizations using synchrotron radiation x ray tomographic microscopy show characteristic fungal morphology of the mycelium like network such as frequent branching anastomosis and septa possible presence of chitin in the hypha walls was detected by staining with wheat germ agglutinin conjugated with fluorescein isothiocyanate and examination using fluorescence microscopy the presence of fungi in subseafloor basalts challenges the present understanding of the deep subseafloor biosphere as being exclusively prokaryotic

structure of the central altyn tagh fault revealed by magnetotelluric data new insights into the structure of the northern margin of the india asia collision abstract the altyn tagh fault atf is a left lateral strike slip fault that forms the northern margin of the tibetan plateau and plays a significant role in accommodating the convergence between the colliding indian and eurasian plates as a part of the fourth phase of the indepth project magnetotelluric mt data were collected across the central segment of the atf to determine the lithospheric scale structure of the fault system dimensionality analyses demonstrated that the mt data can be interpreted using two dimensional approaches but some localized 3 d effects are seen consequently both 2 d and 3 d inversions were carried out and a joint interpretation was made on the basis of these two types of models inversion models revealed two major conductors beneath the qaidam basin qb and altyn tagh range atr respectively the conductive region beneath the qb was interpreted as a ductile layer in the lower crust to upper mantle that might represent flow beneath the western margin of the qb whereas the large scale south dipping conductor beneath the atr is interpreted as a region with high fluid content formed by metamorphism associated with the oblique underthrusting of the tarim block beneath the northern tibetan plateau these fluids migrate upwards through the fault system and have formed serpentinized zones in the crust combining these interpretations a structural model compatible with diverse geophysical observations is proposed in which we suggest the competing end member rigid block model and continuum model are reconcilable with the continuum model locally dominant for the study region as evidenced by a thickened crust

do marine moulds influence hg and si precipitation in the hydrothermal jade field okinawa trough abstract several massive sulfide smoker fragments from the jade field okinawa trough japan yielded filamentous aggregates of both cinnabar hgs and amorphous silica si02 resembling fungal hyphens for this similarity polished and thin sections of filaments were compared with recent moulds that had formed on sulfide samples since the influence of marine moulds on mineral precipitation is poorly known studies on bacterial and algal mineralization mechanisms were reviewed to generally identify microbial metabolism processes that could lead to the formation of the observed filaments the development of hgs pseudomorphs is likely to have occurred through methylation reactions while the filament replacement by silica probably happened via an intermediate formation of silica carbon compounds followed by a successive breakdown of these phases under changing geochemical conditions

tube fossils from gossanites of the urals vhms deposits russia authigenic mineral assemblages and trace element distributions abstract the occurrence types morphology and mineralogical characteristics of tube microfossils were studied in gossanites from twelve vhms deposits of the urals several types of tube microfossils were recognized including siboglinids polychaetes and calcerous serpulids replaced by a variety of minerals e g hematite quartz hematite chlorite carbonate hematite depending on the nature of the substrate prior to the formation of the gossanites colonial hematite tube microfossils 150 m across 1 2 mm long are composed of hematitic outer and inner walls and may exhibit a cellular structure within their cavities spherical forms are saturated with fe oxidizing bacteria inside the tubes probably analogues of trophosomes colloform stromatolitic outer wall surfaces are characterized by the presence of numerous interlaced filaments of hematite 2 3 m diameter up to 1 2 mm long between tube microfossils the hematitized cement contains bundles of hematitized filaments with structures similar to the hyphae of fungi hematite chlorite tube microfossils are scattered in gossanites mostly as biological debris they are typically 30 to 300 m in diameter and 1 to 5 mm long the layered structure of their tube walls is characterized by hematite quartz and chlorite layers abundant filamentous bacteria coated by glycocalix and chlorite stromatolite are associated with hematite chlorite tubes the carbonate hematite tube microfossils up to 300 m across 2 3 mm long occur in carbonate rich gossanites the tubes are characterized by fine 10 m thick walls of hematite and cavities dominated by relatively dark carbonate or hematite carbonates may be present both in walls and cavities stromatolite like leucoxene or hematite carbonate aggregates were also found in association with tubes randomly oriented filaments are composed of ankerite single filaments are composed of individual cells typically smaller than 100 nm across similar to that of magnetotactic bacteria three dimensional tomographic images of all types of tube microfossils demonstrate a clear wavy microlayering from outer and inner walls which may reflect segmentation of the tube worms the traces of burrowing or fragments of glycocalix with relict spheres are typical of tube microfossils from gossanites the carbon isotopic composition of carbonates associated with tube microfossils from hematite quartz hematite carbonate and hematite chlorite gossanites average 7 2 6 8 22 8 pdb respectively these values are indicative of a biogenic origin for the carbonates the oxygen isotopic composition of these carbonates is similar in all three gossanite types averaging 13 5 14 2 13 0 relative to smow and indicative of active sulfate reduction during the diagenetic and anadiagenetic stages of the sediments evolution the trace element characteristics of hematite from tube microfossils are characterized by high contents of following trace elements average ppm mn 1529 as 714 v 540 w 537 mo 35 and u 5 such high contents are most likely the result of metal and metalloid sorption by fine particles of precursor iron hydroxides during the oxidation of sulfides and decomposition of hyaloclasts via microbially mediated reactions

late quaternary paleoseismology and faulting behavior of the yilan yitong fault zone and implications for seismic hazards of the tanlu fault zone eastern china abstract along the north branch of the tanlu fault zone tlfz the yilan yitong fault zone yyfz displaces quaternary geomorphic features forming a 70 km long fresh surface rupture in this study we investigated offset landforms and paleoearthquake history by excavating four trenches along the yyfz within the fangzheng graben combined with quaternary dating of landforms and trench horizons four paleoearthquakes are identified with their timings constrained at 1730 40 a bp to 770 30 a bp 28 5 1 2 ka bp to 21 7 0 9 ka bp 59 4 2 4 ka bp to 33 1 1 1 ka bp and before 59 4 2 4 ka bp respectively seismic recurrence behavior of the yyfz follows a quasi periodic pattern with a very long interval of 10 20 ka geological and geomorphic features show that the yyfz is dominated by right lateral strike slip movement with a low dextral slip rate of 0 2 0 3 mm a in late quaternary in accord with present day geodetic observations as with the yyfz paleoearthquakes along the tlfz commonly share a recurrence interval of 10 20 ka we suggest that active segments of the tlfz that have been dormant for thousands of years may pose significant earthquake hazards in the future moreover strain transfer from the bounding faults to those more central in the graben may be significant on the tlfz and should be given consideration when assessing regional seismic hazards insight into past earthquakes and faulting behavior in a low strain environment is crucial for earthquake hazard analysis and often requires multidisciplinary approaches

a study of the deep electrical structure of the northern segment of the tan lu fault zone ne china abstract we studied a magnetotelluric transect from tongliao inner mongolia to baishan jilin that crosses the northern segment of the tan lu fault zone based on the profiling data we calculated and analyzed the two dimensional 2d deviation degree and the tectonic strike inverted the data using the 2d nonlinear conjugate gradient inversion method and obtained an electrical structure model of the crust and upper mantle along the transect our analysis reveals that the western portion of the transect is within and at the margin of a typical sedimentary basin and a high conductivity layer is present in the lower crust in comparison the eastern portion of the transect is in the jihei fold zone and has a relatively stable electrical structure but its resistivity is one to two orders of magnitude higher than that of the western portion a distinct electrical anomaly exists between the western and eastern sides the yilan yitong fault of the northern segment of the tan lu fault zone dips to the northwest has strike slip characteristics extends to a depth of 40 50 km and induces upwelling of upper mantle materials the dunhua mishan fault of the northern segment of the tan lu fault zone has a clear electrical gradient and similar to the yilan yitong fault it also dips to the northwest however the dunhua mishan fault is mostly fractured extends to a depth of approximately 20 km and is slightly smaller than the yilan yitong fault the inferred distribution of deep resistivity values indicates that the lithosphere is generally thinner at the center of the transect and thicker at the edges the lithosphere is approximately 150 km thick on the western end thins eastward to approximately 60 km thick near the tan lu fault zone and then gradually thickens eastward to 100 km thick

semi arid soils from a topolithosequence at james ross island weddell sea region antarctica chemistry mineralogy genesis and classification abstract climate and parent material have a significant impact on the development of antarctic soils and areas dominated by basaltic andesitic volcanic rocks sedimentary rocks and metamorphic rocks have been widely studied james ross island located in the semi arid transition between east antarctic peninsula weddell sea sector receives both continental and maritime climatic influences resulting in distinct transitional soil formation process in antarctica there is little research on semi arid soils formed on volcano sedimentary rocks as well as their pedogenetic processes in this study a topolithosequence of volcanic and sedimentary rocks in this semi arid transitional climate was investigated nine profiles three on marine terraces four on sedimentary rocks and two on volcanic rocks were described sampled and analyzed for morphological physical chemical and mineralogical properties soils are predominantly gelisols cryosols and present cryoturbation features despite the current dry climate vegetation is scarce and nesting birds are absent so that most soils can be characterized as ahumic all profiles have a skeletic character with a high percentage of coarse materials the soil ph varied from neutral to alkaline and the potential acidity values were null the mineralogy of the clay fraction presented kaolinite which was likely inherited from warmer and wetter paleoclimatic conditions during sedimentation the soils have intergrade properties between maritime and continental antarctic such as cryoturbation and redoximorphism side by side with desert pavements and ahumic character soil properties were more sensitive to the variations in parent material than to the topographic position in the landscape

uav and sfm in detailed geomorphological mapping of granite tors an example of starościnskie skaly sudetes sw poland the paper presents an example of using photographs taken by unmanned aerial vehicles uav and processed using the structure from motion sfm procedure in a geomorphological study of rock relief subject to analysis is a small rock city in the west sudetes sw poland known as staro cinskie skaly and developed in coarse granite bedrock the aims of this paper were first to compare uav sfm derived data with the cartographical image based on the traditional geomorphological field mapping methods and the digital elevation model derived from airborne laser scanning als second to test if the proposed combination of uav and sfm methods may be helpful in recognizing the detailed structure of granite tors as a result of conducted uav flights and digital image post processing in agisoft software it was possible to obtain datasets dense point cloud texture model orthophotomap bare ground type digital terrain model dtm which allowed to visualize in detail the surface of the study area in consequence it was possible to distinguish even the very small forms of rock surface microrelief joints aplite veins rills and karren weathering pits etc otherwise difficult to map and measure the study includes also valorization of particular datasets concerning microtopography and allows to discuss indisputable advantages of using the uav sfm based dtm in geomorphic studies of tors and rock cities even those located within forest as in the presented case study

geomorphological mapping of ice free areas using polarimetric radarsat 2 data on fildes peninsula and ardley island antarctica satellite borne synthetic aperture radar sar has been used for characterizing and mapping in two relevant ice free areas in the south shetland islands the objective has been to identify and characterize land surface covers that mainly include periglacial and glacial landforms using fully polarimetric sar c band radarsat 2 data on fildes peninsula that forms part of king george island and ardley island polarimetric parameters obtained from the sar data a selection of field based training and validation sites and a supervised classification approach using the support vector machine were chosen to determine the spatial distribution of the different landforms eight periglacial and glacial landforms were characterized according to their scattering mechanisms using a set of 48 polarimetric parameters the mapping of the most representative surface covers included colluvial deposits stone fields and pavements patterned ground glacial till and rock outcrops lakes and glacier ice the overall accuracy of the results was estimated at 81 a significant value when mapping areas that are within isolated regions where access is limited periglacial surface covers such as stone fields and pavements occupy 25 and patterned ground over 20 of the ice free areas these are results that form the basis for an extensive monitoring of the ice free areas throughout the northern antarctic peninsula region

inorganic and biogenic as sulfide precipitation at seafloor hydrothermal fields highlights as sulfides are minor minerals at volcanic arc and back arc hydrothermal settings there are two modes of as sulfide precipitation inorganic and biogenic the most stable as sulfide at low t seafloor hydrothermal conditions is orpiment biogenic type of orpiment represents completely mineralized fungal hyphae fungal orpiment precipitation is a mechanism of bio sequestration of hydrothermal as we investigated as sulfides orpiment as2s3 and realgar as4s4 from four seafloor hydrothermal fields three from back arc and one from mid ocean ridge settings our studies suggest two different modes of as sulfide precipitation at the seafloor hydrothermal sites inorganic and biogenic the eh ph modeling shows that the most stable as sulfide at low temperature t 100 c seafloor hydrothermal conditions is orpiment whereas realgar appears as a stable as sulfide phase at t 25 c and under a narrow range of eh ph values inorganically precipitated realgar forms euhedral crystals whereas the orpiment is mostly colloform the biogenic type of orpiment no realgar of this type was found represents completely mineralized fungal hyphae the proposed scenario of biogenic orpiment formation assumes that crack dwelling fungal filaments in the sub seafloor were killed by an as rich hydrothermal fluid moving along the same crack network the fungal organic matter served as a geochemical trap for hydrothermal as which reacted with s leached from the basement or reduced from seawater sulfate and mineralized the fungal hyphae as as2s3 this process of fungal orpiment precipitation is a mechanism of bio sequestration of hydrothermal as and another mode of soft tissue fossilization not described so far

bedded jaspers of the ordovician lokken ophiolite norway seafloor deposition and diagenetic maturation of hydrothermal plume derived silica iron gels sedimentary beds of jasper red hematitic chert in the ordovician lokken ophiolite of norway are closely associated with volcanogenic massive sulphide vms deposits the jaspers occur in the immediate hangingwall and laterally peripheral to the large lokken 25 30 mt and small hoydal 0 1 mt vms deposits and are exposed discontinuously for several kilometres along strike massive or laminated types predominate jasper sulphide debris flow deposits are also abundant near vms deposits the jaspers contain hematite rich laminae showing soft sediment deformation structures and microtextural evidence that record the presence of a colloidal precursor and an origin as gels early textures include 1 straight or curved chains of hematitic filaments 3 10 m in diameter and 20 100 m long 2 branching networks of 15 25 m thick tubular structures surrounded by cryptocrystalline hematite and filled with quartz and euhedral hematite 3 small up to 10 m spherules composed of cryptocrystalline hematite and silica and 4 up to 50 m silica spherules with hematitic cores the small filaments seem to have been deposited in varying proportions in the primary laminae possibly together with hematitic and siliceous microspheroids diagenetic changes are represented by polygonal syneresis cracks and the presence of cryptocrystalline originally opaline silica chalcedony quartz carbonate and cryptocrystalline hematite and or goethite forming botryoidal masses and spheroids 10 m to 5 mm in diameter coarser euhedral grains of quartz carbonate and hematite are integral parts of these textures bleached silica rich jaspers preserve only small relics of fine grained hematite rich domains and locally contain sparse pockets composed of coarse euhedral hematite epidote

geochemistry and morphology of metalliferous sediments and oxyhydroxides from the endeavour segment juan de fuca ridge abstract we present first data on the geochemistry mineralogy and morphology of near vent sediments 35 and 200 m from active vent and ridge flank sediments approximately 3 km from the vent field as well as oxyhydroxide deposits from the endeavour segment juan de fuca ridge the purpose of the study was to understand better the origin and characteristic features of metalliferous sediments associated with base and precious metal massive sulfides in volcanic terrains hydrothermal components in sediments are fe si s rich and mn fe si rich phases sulfides and barite which were exclusively derived from plume fallout sulfides are only a minor constituent of near vent sediments 2 4 wt and were not detected in ridge flank sediments the study suggests that the distribution of hydrothermal phases and associated elements in near vent and ridge flank sediments is affected mainly by processes of agglomeration dissolution absorption and settling that take place within a plume and to a lesser extent post depositional processes rapid deposition of sulfides in the vicinity of the vents is reflected in a sharp drop of the cu concentrations in sediments with increasing distance from the vents besides sulfides important carriers of pb cu zn and co in near vent sediments are fe mn oxyhydroxides that occur together with silica as aggregates of gel like material and flaky particles and as coatings on filaments away from the vents trace metals are mostly in fe mn oxyhydroxides and authigenic fe rich montmorillonite oxyhydroxides at the main endeavour field are interpreted to have originated from oxidation of mound sulfides accompanied by precipitation of primary fe oxyhydroxide silica from low temperature fluids at the mothra field seafloor deposits and chimney crusts composed of fe oxyhydroxide mn silica are considered to be direct precipitates from hydrothermal fluids that have been less diluted with seawater oxyhydroxide deposits exhibit unique microtextures that resemble mineralized microorganisms and may indicate existence of diverse microbial communities

uav based detection and spatial analyses of periglacial landforms on demay point king george island south shetland islands antarctica abstract high resolution aerial images allow detailed analyses of periglacial landforms which is of particular importance in light of climate change and resulting changes in active layer thickness the aim of this study is to show possibilities of using uav based photography to perform spatial analysis of periglacial landforms on the demay point peninsula king george island and hence to supplement previous geomorphological studies of the south shetland islands photogrammetric flights were performed using a pw zoom fixed winged unmanned aircraft vehicle digital elevation models dem and maps of slope and contour lines were prepared in esri arcgis 10 3 with the spatial analyst extension and three dimensional visualizations in esri arcscene 10 3 software careful interpretation of orthophoto and dem allowed us to vectorize polygons of landforms such as i solifluction landforms solifluction sheets tongues and lobes ii scarps taluses and a protalus rampart iii patterned ground hummocks sorted circles stripes nets and labyrinths and nonsorted nets and stripes iv coastal landforms cliffs and beaches v landslides and mud flows and vi stone fields and bedrock outcrops we conclude that geomorphological studies based on commonly accessible aerial and satellite images can underestimate the spatial extent of periglacial landforms and result in incomplete inventories the pw zoom uav is well suited to gather detailed geomorphological data and can be used in spatial analysis of periglacial landforms in the western antarctic peninsula region

timing of formation of neoglacial landforms in the south shetland islands antarctic peninsula regional and global implications abstract the timing of neoglacial advances in the antarctic peninsula ap is not yet well constrained accurate temporal reconstruction of neoglaciation in the ap is needed to better understand past glacial responses and regional and global teleconnections during the holocene here we examine all available information about neoglacial advances in the south shetland islands ssi as well as in the broader geographical context of the ap region and antarctic continent in order to shed light on the contrasting chronologies existing for neoglacial advances in these regions we focused on a case study where a detailed picture of the holocene deglaciation was already available lake sediments revealed that byers peninsula west of livingston island ssi was fully deglaciated during the holocene thermal maximum to complement this approach we identified glacially polished bedrock surfaces erratic boulders and a moraine ridge near the present front of the glacier in the se corner we applied cosmogenic ray exposure cre dating using in situ 36cl for basalt rocks and 10be for granitic rocks in i 8 samples from glacial erratic and ice rafted boulders ii 2 samples from moraine boulders iii 2 samples from polished bedrock surfaces and iv 1 sample from an erratic boulder deposited on one of these surfaces the cre dates indicate that the onset of deglaciation started around 9 9 1 2 ka with two phases of glacier expansion during the mid late holocene forming moraines at 4 1 0 5 and 1 0 0 2 ka respectively the main neoglacial advances in the ap and the ssi were mostly synchronous and coincided with cold periods as shown by other records e g glacio isostatic marine terraces marine and lake sediments in addition these periods of glacial expansion show a similar timing to those recorded in the arctic these results suggest that neoglaciation was driven by global climate forcing in both polar areas despite temporal variations at regional and local scale

metamorphism of volcanogenic massive sulphide deposits in the urals ore geology abstract the urals vms province comprises a broad spectrum of variably metamorphosed deposits from unmetamorphosed to those without any primary ore textures which are the results of high grade metamorphic processes contact metamorphism near large granite and granodiorite plutons caused the most significant changes of ores with coarse grained to pegmatoidal ores with magnetite closest to its contact with the intrusion followed by pyrrhotite enriched copper ores and more distal zinc pb ag mineralisation koktau tarnyer and vesenneye deposits are metamorphosed to the hornblende hornfels and pyroxene hornfels facies t 400 800 c p 1 6 kbar metamorphism of tash yar dzhusinskoe and krasnogvardeiskoe deposits corresponds to the greenschist and albite epidote hornfels facies t 250 450 c p 1 4 kbar the regional metamorphism of vms ores varies from prehnite pumpellyite facies t 150 300 c p 0 5 4 kbar in the south urals to the epidote amphibolite and amphibolite facies t 400 600 c up to 700 c p 1 6 kbar in the karabash area in the middle urals in the magnitogorsk zone the metamorphism of host rocks and vms bodies increases to the north reaching its peak near the ufa promontory of the east european platform with increased metamorphism the morphology of orebodies evolves from gently dipping thick lenses alexandrinskoe and uzelga fields to subvertical and folded uchaly and novo uchaly deposits and pseudomonoclinal steeply dipping vein like bodies karabash district the massive sulphide transformation in ptx gradient fields led to partial redistribution of ore material an enrichment in cu zn ag and au pb occur in the uppermost parts of large steeply dipping massive sulphide lenses in wide tectonic zones e g gai deposit or as gold sulphide disseminated bodies near large metamorphosed vms lenses distal to a granite pluton tarnyer deposit partial melting probably occurred in some highly metamorphosed deposits tarnyer koktau and mauk redeposition of base metals sulphides chalcopyrite tennantite sphalerite bornite galena as well as the presence of visible gold and tellurides took place during retrograde metamorphism which produced a transfer of ore matter towards the low stress areas such as the outer parts of shear zones the uppermost parts of steeply dipping ore lenses pressure shadows hinge zones of small folds and small extension fractures i e alpine type veins in deformed ore body or its immediate surroundings

chimneys in paleozoic massive sulfide mounds of the urals vms deposits mineral and trace element comparison with modern black grey white and clear smokers in the urals a wide range of well preserved chimneys are found in vms deposits which are associated with ultramafic atlantic type dergamysh mafic cyprus type buribay bimodal mafic uralian type yubileynoye sultanovskoye yaman kasy molodezhnoye uzelga 4 valentorskoye and bimodal felsic kuroko or baymak type oktyabrskoye tash tau uselga 1 talgan alexandrinskoye sequences chimneys have also been found in the safyanovskoye deposit altay type that is hosted by intercalated felsic lavas and carbonaceous shales a combination of geological mineralogical and trace element data provide a general outline for comparison between chimneys from the urals deposits and modern vent sites the chimneys from the dergamysh deposit show a broad affinity with those from the rainbow and other vent sites associated with serpentinites of the mid atlantic ridge the chimneys from the buribay deposit are similar to the black smokers of the epr vent sites including the scarcity of rare minerals the chimneys from the urals type of the vms deposits show some similarities with grey smokers from the brother volcano and pacmanus sites the chimneys from the baymak type of the vms deposits resemble grey and white smokers of the pacmanus and grey smokers of the suiyo vent sites the chimneys from the safyanovskoye deposit are similar to the black and clear smokers from the okinawa trough mineral assemblages are controlled by the combination of host rock composition and physico chemical conditions of the ore forming processes amount of colloform pyrite isocubanite and pseudomorphic pyrite and marcasite after pyrrhotite decreases in the chimneys across the range from ultramafic and mafic to felsic hosted deposits and is concomitant with increase in the contents of sphalerite galena bornite fahlores native gold and barite across this range the chimneys from the urals type contain abundant tellurides and sulfoarsenides while these minerals are rare except for hessite in the baymak type deposits in the same range the buffering capacity of host rocks decreases in contrast to the increase in s2 and o2 with the exception of the safyanovskoye deposit trace element assemblages in chalcopyrite vary to reflect the host rock ultramafic high se sn co ni ag and au mafic high co se mo and low bi au and pb bimodal mafic high te au ag bi pb co moderate se and variable as and sb bimodal felsic high as sb mo pb moderate bi and low co te and se in sphalerite of the same range the contents of bi pb ag au and sb increase versus fe se and o the variations in trace elements in colloform pyrite coincide with these changes the specific mineral changes in the local ranges from cu to zn rich chimneys in each vms deposit are similar to the general changes in the range of host rock classes of the deposits however the local t s2 and o2 changes can broadly be interpreted in terms of contribution of variable oxygenated cold seawater to the subseafloor and seafloor hydrothermal processes

hydrothermal chert and associated siliceous rocks from the northern pacific their geological significance as indication od ocean ridge activity adachi m yamamoto k and sugisaki r 1986 hydrothermal chert and associated siliceous rocks from the northern pacific their geological significance as indication of ocean ridge activity sediment geol 47 i25 148 analyses of 42 cretaceous rock samples from deep sea drilling project dsdp leg 32 in tile northern pacific show that chert and porcellanite are enriched in fe mn p cu ba mo ni and pb relative to both triassic biogenic cherts of central japan and cretaceous dsdp cherts of leg 62 the iron enrichment up to 6 68ve fe20 as total iron is most prominent in chert immediately overlying basal basah which is the only chert free of radiolarians and veined by megaquartz containing many fluid inclusions chemical features characterized by a low ratio for a1 ai fe mn and ai z tio 2 and a high ratio for total fe2oj tio 2 mno tio 2 and mo tio 2 as well as petrological evidence indicatc that the cherts formed in an intense submarine hydrothermal environment on or near the cretaceous japanese spreading center which separated the kula plate from the pacific plate the spreading rate of the cretaceous japanese spreading center estimated from the chemical composition of the cherts was about 3 7 cm r i the rate is comparable to that inferred from the geomagnetic data

active layer dynamics in three topographically distinct lake catchments in byers peninsula livingston island antarctica abstract topography exerts a key role in controlling permafrost distribution in areas where mean annual temperatures are slightly negative one such case is the low altitude environments of maritime antarctica where permafrost is sporadic to discontinuous below 20 40 m asl and continuous at higher areas and active layer dynamics are thus strongly conditioned by geomorphological setting in january 2014 we installed three sites for monitoring active layer temperatures across byers peninsula livingston island south shetland islands at elevations between 45 and 100 m the sites are situated in lake catchments lakes escondido cerro negro and domo that have different geomorphological and topographical conditions our objective was to examine the role of topography and microclimatic conditions in determining the active layer thermal regime in order to identify the factors that control geomorphic processes in these lake catchments at each site a set of loggers was installed to monitor air temperature at snow thickness swt and soil temperature st down to 80 cm depth mean annual air temperatures maat showed similar values in the three sites 2 7 to 2 6 c whereas soil temperatures showed varying active layer thicknesses at the three catchments the ground thermal regime was strongly controlled by soil properties and snow cover thickness and duration which is influenced by local topography geomorphological processes operating at the lake catchment scale control lacustrine sedimentation processes and both are dependent on the combination of topographical and climatic conditions therefore the interpretation of lake sediment records from these three lakes requires that soil thermal regime and snow conditions at each site be taken into account in order to properly isolate the geomorphological environmental and climatic signals preserved in these lake records

high resolution mantle tomography of china and surrounding regions 1 a high resolution p wave tomographic model of the crust and mantle down to 1100 km depth under china and surrounding regions is determined by using about one million arrival times of p pp pp and pcp waves from 19 361 earthquakes recorded by 1012 seismic stations the subducting pacific slab is imaged clearly as a high velocity zone from the oceanic trenches down to about 600 km depth and intermediate depth and deep earthquakes are located within the slab the pacific slab becomes stagnant in the mantle transition zone under east china the western edge of the stagnant slab is roughly coincident with a surface topographic boundary in east china the active changbai and wudalianchi intraplate volcanoes in northeast china are underlain by significant slow anomalies in the upper mantle above the stagnant pacific slab these results suggest that the active intraplate volcanoes in ne china are not hot spots but a kind of back arc volcano associated with the deep subduction of the pacific slab and its stagnancy in the transition zone under the mariana arc however the pacific slab penetrates directly down to the lower mantle the active tengchong volcano in southwest china is related to the eastward subduction of the burma microplate the subducting indian and philippine sea plates are also imaged clearly the indian plate has subducted down to 200 300 km depth under the tibetan plateau with a horizontal moving distance of about 500 km high velocity anomalies are revealed in the upper mantle under the tarim basin ordos and sichuan basin which are three stable blocks in china

influence of a tube building polychaete on hydrothermal chimney mineralization high temperature chimneys on the juan de fuca ridge are the preferred habitat of the sulfide worm paralvinella n sp an investigation of interactions between the biology of the sulfide worm and chimney mineralization has led to a hypothesis linking formation of marcasite pyrite crusts on chimney surfaces to colonization and tube building by the worms marcasite precipitation beneath worm tubes and worm migration to newly formed areas of chimney together create a moving front of biomineralization that keeps pace with chimney growth sulfide oxidation by this organism can potentially produce enough s to form the fes sub 2 crusts the marcasite pyrite crusts act as a sealing layer within the outer chimney wall reducing inflow of cold seawater or outflow of hydrothermal fluid this may enhance temperature increases within the chimney conduit and hasten replacement of the early anhydrite matrix in the chimney wall by higher temperature sulfides

seismic structure and origin of active intraplate volcanoes in northeast asia abstract three dimensional p wave velocity structure beneath the changbai and other intraplate volcanic areas in northeast asia is determined by inverting 1378 high quality p wave arrival times from 186 teleseismic events recorded by 61 broadband seismic stations low velocity low v anomalies are revealed beneath the changbai longgan xianjindao volcanoes high velocity high v anomalies are found in the mantle transition zone where deep focus earthquakes under hunchun occur at depths of 500 600 km the high v anomaly reflects the deep subduction of the pacific slab under ne asia which may have contributed to the formation of the changbai longgang xianjindao and jingpohu intraplate volcanoes a low v anomaly is also revealed in the mantle transition zone which may have a close relationship with the occurrence of deep earthquakes under the hunchun area our results support the big mantle wedge bmw model by zhao et al zhao d lei j tang y 2004 origin of the changbai volcano in northeast china evidence from seismic tomography chin sci bull 49 1401 1408 zhao d maruyama s omori s 2007 mantle dynamics of western pacific and east asia insight from seismic tomography and mineral physics gondwana res 11 120 131 who proposed that the intraplate volcanoes in ne asia are caused by the back arc magmatism associated with the deep dehydration process of the subducting slab and convective circulation process in the bmw above the stagnant pacific slab

soil characteristics on varying lithological substrates in the south shetland islands maritime antarctica abstract soils in ice free areas of livingston island have been forming since the last deglaciation in a maritime warmer climate that is more humid than in interior antarctica a soil survey was carried out on byers and hurd peninsulas to characterize the soils and investigate the processes soils were sampled on two different substrates mudstones and volcanic rocks in byers peninsula and greywackes in hurd peninsula sampling sites were located on raised beaches platforms and on volcanic outcrops across an altitudinal range from few m to 150 m a s l the ph electrical conductivity carbonates and organic matter showed similar patterns in each geomorphic unit but their values differed between bedrocks the sand silt and clay contents differed greatly in the soils on mudstones and volcanic rocks the elemental composition was closely related to mineralogy of parent materials mg k zn mn and fe were similar in the soils on all bedrocks the al content was highest on the volcanic rocks the largest difference in the ca content was between the soils on greywackes and mudstones the na pb and ba contents in soils on the mudstones differed greatly from the rest of bedrocks geochemical and mineralogical characteristics suggest that the main process involved in soil development was the mechanical disintegration of bedrock although there was also some leaching cryogenic processes play a key role in soil development but chemical weathering processes were also involved in soil evolution although limited in extent due to the restriction of water circulation to summer

evaluation of frozen ground conditions along a coastal topographic gradient at byers peninsula livingston island antarctica by geophysical and geoecological methods abstract geophysical surveying and geoelectrical methods are effective to study permafrost distribution and conditions in polar environments geoelectrical methods are particularly suited to study the spatial distribution of permafrost because of its high electrical resistivity in comparison with that of soil or rock above 0 c in the south shetland islands permafrost is considered to be discontinuous up to elevations of 20 40 m a s l changing to continuous at higher altitudes there are no specific data about the distribution of permafrost in byers peninsula in livingston island which is the largest ice free area in the south shetland islands with the purpose of better understanding the occurrence of permanent frozen conditions in this area a geophysical survey using an electrical resistivity tomography ert methodology was conducted during the january 2015 field season combined with geomorphological and ecological studies three overlapping electrical resistivity tomographies of 78 m each were done along the same profile which ran from the coast to the highest raised beaches the three electrical resistivity tomographies are combined in an electrical resistivity model which represents the distribution of the electrical resistivity of the ground to depths of about 13 m along 158 m several patches of high electrical resistivity were found and interpreted as patches of sporadic permafrost the lower limits of sporadic to discontinuous permafrost in the area are confirmed by the presence of permafrost related landforms nearby there is a close correspondence between moss patches and permafrost patches along the geoelectrical transect

mineralogy bulk and rare earth element geochemistry of massive sulphide associated hydrothermal sediments of the brunswick horizon bathurst mining camp new brunswick massive sulphides are spatially and temporally associated with iron formation if and other hydrothermal sedimentary rocks in the vicinity of the brunswick no 12 brunswick no 6 and austin brook deposits bathurst mining camp sulphide carbonate oxide and silicate predominant if is present carbonate predominant if is best developed in and around the brunswick no 12 deposit whereas hematite bearing if is absent here but prominent in the austin brook brunswick no 6 area the if is composed dominantly of si co2 fe mn and ca minor constituents include mg p ti al and s statistically significant interelement correlations between eu fe mn pb zn cd au ca sr ba p co2 and s indicate that these elements were precipitated from hydrothermal fluids vented onto the seafloor positive interelement correlations between si ti al mg k zr rare earth elements ree s except eu se v y yb co ni and cr reflect the presence of detrital clastic mafic and aluminosilicate minerals and

karst landforms revealed at various scales using lidar and uav in semi arid brazil consideration on karstification processes and methodological constraints abstract this paper analyzes different types of karst landforms and their relationships with fracture systems sedimentary bedding and fluvial processes we mapped karst features in the cretaceous carbonates of the jandaira formation in the potiguar basin brazil we used high resolution digital elevation models acquired using lidar and aerial orthophotographs acquired using an unmanned aerial vehicle uav we grouped and described karst evolution according to scale and degree of karstification these degrees of karst evolution are coeval fractures are opened by dissolution forming vertical fluid conduits whereas coeval dissolution occurs along horizontal layers this conduit system acts as pathways for water flow the enlargement of conduits contributes to the collapse of blocks in sinkholes and expansion of caves during an intermediate degree of karstification propagation of dissolution can cause the coalescence of sinkholes and the capture of small streams fluvial processes dominate karst dissolution at an advanced degree of karstification comparisons with previously published ground penetrating radar gpr borehole and seismic surveys in sedimentary basins indicate that these structures can be partially preserved during burial

uranium enrichment in metalliferous sediments from the mid atlantic ridge abstract previous studies of metal rich sediments at mid ocean ridge spreading centres have suggested that u fe ratios are relatively constant from site to site a suite of cores from the mid atlantic ridge has been analysed for u and fe content and most samples exhibit constant u fe ratios sulphide bearing parts of one core however contain excess u compared with that observed in other metalliferous sediments but apparently only during oxidative alteration of pyrite phases fission track registration has demonstrated that this excess u is intimately associated with sulphide grains in the sediment scanning electron microscope examination indicates that this u enrichment is limited to very small areas within the oxidation layer and is associated with an enhanced p concentration ion probe analyses allow semi quantitative analyses of various elements through a u rich grain the observed distribution of u coupled with its specific enrichment suggests that microbial mediation might be controlling this enrichment u fe ratios in fully oxidised tag sediments are constant and approximately an order of magnitude higher than in young plume particulates this discrepancy is attributed to a second type of post depositional u enrichment producing an homogeneous distribution of u throughout the sediment

stress state differences between sedimentary cover and basement of the songliao basin ne china in situ stress measurements at 6 7 km depth of an icdp scientific drilling borehole sk ii abstract the stress state down to the basement within sedimentary basins yet remains poorly understood the anelastic strain recovery asr method was employed to measure the stress state in the sk ii borehole in the songliao basin northeast china the results show that the stress state differs significantly between the sedimentary cover and basement in the sedimentary cover 6296 6335 m the maximum principal stress 1 is nearly vertical which is in the normal faulting stress regime dominated by gravitation in accordance with the normal faults observed on seismic reflection profiles within the sedimentary cover in contrast the basement 6646 6846 m shows that 1 is nearly horizontal suggesting a strike slip or reverse faulting regime the stress state of the basement is close to the reasonable stress condition for the eurasian plate far from a western pacific plate subduction zone and consistent with the focal mechanisms of earthquakes 7 15 km in the vicinity of icdp sk ii borehole the difference of stress state may imply that the far field stress generated by the western pacific plate has limited effects on the sedimentary cover an increase in thickness correlates with an increasing influence of tectonic stress with depth

on the role of microbes in the alteration of submarine basaltic glass a tem study abstract the alteration of submarine basaltic glass that has been attributed to microbial activity was investigated via transmission electron microscopy in order to document glass alteration and to understand the chemical reactions that bacteria could utilize the features that were examined occur within fresh glass at the alteration front and consist of 0 1 2 3 m patches or tubes of phyllosilicates rimmed by 0 1 0 3 m wide zones of altered glass the altered glass has lost significant mg fe ca and na slight amounts of al and mn and exhibits an order of magnitude increase of k this incongruent dissolution occurred at neutral to acid ph and temperatures 100 fracture volumes which may be important for the supply of nutrients for microbial activity

diagenesis of titaniferous minerals in jurassic sandstones from the norwegian sea abstract ti oxides anatase and in some cases rutile that attain various textures and modes of occurrence are minor yet very common authigenic minerals in the jurassic sandstones of the haltenbanken oil field offshore central norway these ti oxides pyrite commonly occur as pseudomorphs after detrital fe ti oxides usually ilmenite titanomagnetite and titanohematite pseudomorphs comprised of ti oxides as well as quartz and or calcite are believed to result upon alteration of detrital sphene ti oxides have also resulted upon kaolinization of detrital biotite and less significantly muscovite authigenic sphene occurs in very small amounts in some of the jurassic sandstones at burial depths 2000 m it displays three major crystallization habits 1 as almond shaped crystals that have most commonly crystallized on authigenic calcite 2 as discrete rhombic crystals that have crystallized adjacent to altered fe ti oxides and biotite and 3 as aggregates of euhedral and subhedral crystals these crystallization habits suggest that sphene has been formed by reaction of si and ti ions with calcite crystallization from pore fluids and replacement of fe ti oxides respectively microprobe analyses of authigenic sphene revealed that al and fe 3 substitute ti in appreciable amounts average 0 08 and 0 04 moles per 5 oxygen atoms respectively whereas substitutions of ca by mn k and na and of ti by mg are negligible

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

rock glaciers in the south shetland islands western antarctica rock glaciers are found in the peripheral regions of antarctica particularly in the antarctic peninsula region study of these features is relevant for the palaeoenvironmental reconstruction of maritime antarctica because they are indicators of permafrost and periglacial conditions this paper reports and analyzes the results of an inventory of rock glaciers and protalus lobes in the south shetland islands nine rock glaciers and eleven protalus lobes have been identified all of them are located in recently deglaciated zones between 300 m a s l and sea level and they cover an area of 497 103 m2 tongue shaped rock glaciers are more common than lobate types being in general of medium and small sizes they are talus rock glaciers 55 and debris rock glaciers 45 according to the genetic classification the lack of a preferred orientation suggests that there is no significant microclimate control on their distribution they are related to particular morphodynamic situations estimated annual velocities based on relationships with raised beaches and transported debris volumes range between 2 4 and 97 cm year 1 within the ranges reported for other rock glaciers three groups of rock glaciers can be recognised a those immediate postdating the last major ice recession b rock glaciers younger than 2000 years bp but pre dating the little ice age lia and c rock glaciers formed during the lia

corrosion patterns of seep carbonates from the eastern mediterranean sea terra nova 23 206 212 2011 abstract porous seep carbonates are exposed at mud volcanoes in the eastern mediterranean sea the 13c depleted aragonitic carbonates formed as a consequence of the anaerobic oxidation of methane in a shallow sub surface environment besides the macroscopically visible cavernous fabric extensive carbonate corrosion was revealed by detailed analysis after erosion of the background sediments the carbonates became exposed to oxygenated bottom waters that are periodically influenced by the release of methane and upward diffusion of hydrogen sulphide we suggest that carbonate corrosion resulted from acidity locally produced by aerobic oxidation of methane and hydrogen sulphide in the otherwise with respect to aragonite oversaturated bottom waters although it remains to be tested whether the mechanisms of carbonate dissolution suggested herein are valid this study reveals that a better estimate of the significance of corrosion is required to assess the amount of methane derived carbon that is permanently fixed in seep carbonates

uav based remote sensing of the super sauze landslide evaluation and results unmanned aerial vehicles uavs equipped with digital compact cameras can be used to map landslides quickly and at a high ground resolution images taken by a radio controlled mini quad rotor uav of the super sauze france landslide have been used to produce a high resolution ortho mosaic of the entire landslide and digital terrain models dtms of several regions the uav capability for imaging fissures and displacements on the landslide surface has been evaluated and the subsequent image processing approaches for suitably georectifying the data have been assessed for super sauze horizontal displacements of 7 to 55 m between a high resolution airborne ortho photo of may 2007 and a uav based ortho mosaic of october 2008 have been measured fixed areas of persistent deformation have been identified producing fissures of different distributions and orientations comparable to glacial crevasses and relating directly to the bedrock topography the uav has demonstrated its capability for producing valuable landslide data but improvements are required to reduce data processing time for the efficient generation of ortho mosaics based on photogrammetric dtms in order to minimise georeferencing errors

hurd peninsula glaciers livingston island antarctica as indicators of regional warming ice volume changes during the period 1956 2000 johnsons and hurd glaciers are the two main glacier units of hurd peninsula ice cap livingston island south shetland islands antarctica they presently cover an area of about 10 km 2 johnsons is a tidewater glacier while hurd glacier ends on emerged land in this paper we estimate the changes in ice volume during the period 1956 2000 and compare them with the regional meteorological records the volume change estimates are based on the comparison of digital terrain models for the glacier surface constructed from aerial photographs taken by the british antarctic survey in 1956 and from our geodetic measurements in 1999 2000 the total volume estimates are based on an ice thickness map constructed from radio echo sounding profiles 18 25 mhz done in 1999 2001 showing maximum ice thickness of about 200 m we estimate the changes in ice volume during the period 1956 2000 to be 0 108 0 048 km 3 which represents a 10 0 4 5 decrease from the 1956 total volume of 1 076 0 055 km 3 and is equivalent to an average annual mass balance of 0 23 0 10 m w e during 1956 2000 ice thickness changes range from 40 to 20 m averaging 5 5 4 4 m most areas show ice thinning the thickening is limited to a small area within johnsons glacier all glacier fronts except johnsons calving front show retreat these changes are consistent with the regional meteorological records for mean summer temperature which show a trend of 0 023 0 0058 ca 1 during the period 1956 2000

a simplified method to estimate the run off in periglacial creeks a case study of king george islands antarctic peninsula although the relationship between surface air temperature and glacial discharge has been studied in the northern hemisphere for at least a century similar studies for antarctica remain scarce and only for the past four decades this data scarcity is due to the extreme meteorological conditions and terrain inaccessibility as a result the contribution of glacial discharge in antarctica to global sea level rise is still attached with great uncertainties especially from partly glaciated hydrological basins as can be found in the antarctic peninsula in this paper we propose a simplified model based on the monte carlo method and fourier analysis for estimating discharge in partly glaciated and periglacial hydrological catchments with a summer melt period our model offers the advantage of scarce data requirements and quick recognition of periglacial environments discharge was found to be highly correlated with surface air temperature for the partially glaciated hydrological catchments on potter peninsula king george island isla 25 mayo the model is simple to implement and requires few variables to make most versatile simulations we have obtained a monthly simulated maximum flow estimates between 0 74 and 1 07 m 3 s 1 for two creeks south and north potter with a very good fit to field observations the glacial mean monthly discharge during summer months was estimated to 0 44 0 02 m 3 s 1 for south potter creek and 0 55 0 02 m 3 s 1 for north potter creek this article is part of the theme issue the marine system of the west antarctic peninsula status and strategy for progress in a region of rapid change

mantle transition zone stagnant slab and intraplate volcanism in northeast asia 3 d p and s wave velocity structures of the mantle down to a depth of 800 km beneath ne asia are investigated using similar to 981 000 high quality arrival time data of local earthquakes and teleseismic events recorded at 2388 stations of permanent and portable seismic networks deployed in ne china japan and south korea our results do not support the existence of a gap or a hole in the stagnant slab under the changbai volcano which was proposed by a previous study of teleseismic tomography in this work we conducted joint inversions of both local earthquake arrival times and teleseismic relative traveltime residuals leading to a robust tomography of the upper mantle and the mantle transition zone mtz beneath ne asia our joint inversion results reveal clearly the subducting pacific slab beneath the japan islands and the japan sea as well as the stagnant slab in the mtz beneath the korean peninsula and ne china a big mantle wedge bmw has formed in the upper mantle and the upper part of the mtz above the stagnant slab localized low velocity anomalies are revealed clearly in the crust and the bmw directly beneath the active changbai and ulleung volcanoes indicating that the intraplate volcanism is caused by hot and wet upwelling in the bmw associated with corner flows in the bmw and deep slab dehydration as well

holocene climate and glacial history of the northeastern antarctic peninsula the marine sedimentary record from a long shaldril core abstract a high resolution record of holocene deglacial and climate history was obtained from a 77 m sediment core from the firth of tay antarctic peninsula as part of the shaldril initiative this study provides a detailed sedimentological record of holocene paleoclimate and glacial advance and retreat from the eastern side of the peninsula a robust chronostratigraphy was derived from thirty three radiocarbon dates on carbonate material this chronostratigraphic framework was used to establish the timing of glacial and climate events derived from multiple proxies including magnetic susceptibility electric resistivity porosity ice rafted debris content organic carbon content nitrogen content biogenic silica content and diatom and foraminiferal assemblages the core bottomed out in a stiff diamicton interpreted as till gravelly and sandy mud above the till is interpreted as proximal glaciomarine sediment that represents decoupling of the glacier from the seafloor circa 9400 cal yr bp and its subsequent landward retreat this was approximately 5000 yr later than in the bransfield basin and south shetland islands on the western side of the peninsula the firth of tay core site remained in a proximal glaciomarine setting until 8300 cal yr bp at which time significant glacial retreat took place deposition of diatomaceous glaciomarine sediments after 8300 cal yr bp indicates that an ice shelf has not existed in the area since this time the onset of seasonally open marine conditions between 7800 and 6000 cal yr bp followed the deglacial period and is interpreted as the mid holocene climatic optimum open marine conditions lasted until present with a minor cooling having occurred between 6000 and 4500 cal yr bp and a period of minor glacial retreat and or decreased sea ice coverage between 4500 and 3500 cal yr bp finally climatic cooling and variable sea ice cover occurred from 3500 cal yr bp to near present and it is interpreted as being part of the neoglacial the onset of the neoglacial appears to have occurred earlier in the firth of tay than on the western side of the antarctic peninsula the medieval warm period and little ice age were not pronounced in the firth of tay the breadth and synchroneity of the rapid regional warming and glacial retreat observed in the antarctic peninsula during the last century appear to be unprecedented during the holocene epoch

debris flow dominance of alluvial fans masked by runoff reworking and weathering arid alluvial fan aggradation is highly episodic and fans often comprise active and inactive sectors hence the morphology and texture of fan surfaces are partly determined by secondary processes of weathering and erosion in addition to primary processes of aggradation this introduces considerable uncertainty in the identification of formative processes of terrestrial and martian fans from aerial and satellite imagery the objectives of this study are i to develop a model to describe the sedimentological and morphological evolution of inactive fan surfaces in arid settings and ii to assess the relative importance of primary processes of aggradation and secondary processes of weathering and reworking for surface morphology and sedimentology and for the stratigraphic record we studied an alluvial fan characterized by a recently active sector and a long abandoned inactive sector along the coast of the hyperarid atacama desert here rates of primary geomorphic activity are exceptionally low because of extreme aridity while weathering rates are relatively high because of the effects of coastal fogs long term processes of fan aggradation and reworking were determined through sedimentological facies analysis of stratigraphic sections ground surveys for textural and morphological patterns at the fan surface were integrated with remote sensing by an unmanned airborne vehicle uav discharges and sediment transport capacities were calculated to estimate the efficiency of secondary runoff in reshaping the inactive fan sector stratigraphic sections reveal that the fan was dominantly aggraded by debris flows whereas surface morphology is dominated by debris flow signatures in the active sector and by weathering and runoff on the inactive sector on the latter rapid particle breakdown prevents the formation of a coarse desert pavement furthermore relatively frequent local runoff events erode proximal debris flow channels on the inactive sector to form local lag deposits and accumulate fine sediment in low gradient distal channels forming a well developed drainage pattern that would suggest a runoff origin from aerial images nevertheless reworking is very superficial and barely preserved in the stratigraphic record this implies that fans on earth and mars that formed dominantly by sporadic mass flows may be masked by a surface morphology related to other processes

cambrian microbial and silica gel textures in silica iron exhalites from the mount windsor volcanic belt australia their petrography chemistry and origin stratiform quartz hematite or magnetite lenses ironstones occur sporadically throughout the mount windsor volcanic belt at three main stratigraphic positions including along strike from and immediately stratigraphically above the thalanga massive sulfide deposit the area is ideal for examination of the chemical textural and mineralogical changes which occur in silica iron exhalites around ancient hydrothermal submarine vent sites major and trace element chemical data for the ironstones indicate they are essentially composed of sio 2 and fe 2 o 3 generally 99 wt with very low concentrations of other oxides e g al 2 o 3 generally 0 5 wt and trace elements across the length of the mount windsor volcanic belt most of the ironstones have experienced substantial recrystallization at metamorphic grades from greenschist to amphibolite facies however a number of samples from the eastern part of the belt are less recrystallized prehnite pumpellyite facies and retain abundant evidence of microbial fossils and the inorganic maturation of amorphous phases at least three distinct microbial morphologies are recognized 1 approximately 1 mu m avg diam filaments with septa 2 approximately 3 mu m avg diam filaments with no septa and 3 20 to 30 mu m avg diam filaments with no reconnecting branches the range in metamorphic grade along the mount windsor volcanic belt not only permits a rare insight into the primary textures of ancient exhalites but also a useful view of the textural and mineralogical changes which accompany the progressive increase in temperature up to amphibolite facies conditions comparisons with similar modern deposits and experimentally produced synthetic textures suggest that the ironstones formed from the crystallization of silica iron oxyhydroxide gels these gels formed as a result of mixing between hydrothermal fluid and seawater and conductive cooling of the product the rare earth element geochemistry of ironstones along strike from thalanga is compatible with migration of a hydrothermal fluid away from the vent center followed by its accumulation and cooling in topographic depressions on the sea floor microaerophilic chemolithotrophic bacteria and or fungi probably catalyzed the oxidation of fe super 2 to fe super 3 several metamorphosed ironstones also contain pyrite with delta 34 s values approximately 50 per mil lighter than cambrian sulfate suggesting the activity ofsulfate reducing bacteria at some point during their formation the temperature of the original hydrothermal fluid was probably between 10 degrees and 40 degrees c originating either as the in situ product of weak hydrothermal activity in which inorganic sulfate reduction did not occur or as the cooled remnant of a higher temperature fluid which had already deposited sulfides the inferred mode of deposition for the siliceous ironstones as a gel is different from that of many modern iron oxyhydroxide precipitates which form by settling of particles to the sea floor from hydrothermal plumes on the flanks of the thalanga massive sulfide deposit some iron silica exhalites have been encompassed by massive sulfide suggesting that the early low temperature fe si precipitates were subsequently overprinted by hotter fluids this provides good evidence for waxing and waning in the life of the vent system

carbon isotope distribution in organic matter and siderite of a modern metalliferous hydrothermal sediment and possible implications for gold associated with banded iron formation abstract the carbon isotope distribution in organic matter and siderite has been determined in the metalliferous ferruginous sediments of santorini greece the sediments were precipitated by the microaerophilic chemolithotrophic bacterium galionella ferruginea from reduced hydrothermal solutions in siderites precipitated due to high co2 fugacity the 13 c 12 c isotope ratio pdb was 6 5 permil whereas the ratio was 26 8 permil in organic matter produced by the bacteria the common occurrence of isotopically light carbon 13c 10 permil pdb in carbonates of banded iron formations bif s was proposed some years ago to be the result of the dilution of carbon of marine carbonates by isotopically light carbon originally present in organic matter the explanation for this dilution would be that fe iii in newly precipitated oxide hydroxides served as an electron acceptor during oxidation of the organic carbon to carbonate the corresponding redistribution of some reduced carbon in the newly precipitated ferruginous sediment to carbonate minerals in the proportions found in some bif s has been modelled in the present study the isotopic shift to 13c 11 2 permil of the carbonate minerals of such a dilution by carbon of biological origin is close to the values observed in the geological record therefore organic matter appears to have been much more abundant during the early phases of bif development the association of gold and reduced organic carbon is well established in for instance the witwatersrand type conglomerates and some archaean bif s of hydrothermal origin this association may therefore make it worthwhile evaluating once again the role of organic activity in the deposition of bif s and their potential as a source of gold

the identification and biogeochemical interpretation of fossil magnetotactic bacteria magnetotactic bacteria which most commonly live within the oxic anoxic transition zone oatz of aquatic environments produce intracellular crystals of magnetic minerals specifically magnetite or greigite the crystals cause the bacteria to orient themselves passively with respect to the geomagnetic field and thereby facilitate the bacteria s search for optimal conditions within the sharp chemical gradients of the oatz the bacteria may also gain energy from the redox cycling of their crystals because magnetotactic bacteria benefit from their magnetic moments natural selection has promoted the development of traits that increase the efficiency with which the intracellular crystals impart magnetic moments to cells these traits also allow crystals produced by magnetotactic bacteria called magnetofossils when preserved in sediments to be distinguished from abiogenic particles and particles produced as extracellular byproducts of bacterial metabolism magnetofossils are recognizable based on their narrow size and shape distributions distinctive morphologies with blunt crystal edges chain arrangement chemical purity and crystallographic perfection this article presents a scheme for rating magnetofossil robustness based on these traits the magnetofossil record extends robustly to the cretaceous and with lesser certainty to the late archean because magnetotactic bacteria predominantly live in the oatz the abundance and character of their fossils can reflect environmental changes that alter the chemical stratification of sediments and the water column the magnetofossil record therefore provides an underutilized archive of paleoenvironmental information several studies have demonstrated a relationship between magnetofossil abundance and glacial interglacial cycles likely mediated by changes in pore water oxygen levels more speculatively a better developed magnetofossil record might provide constraints on the long term evolution of marine redox stratification more work in modern and ancient settings is necessary to explicate the mechanisms linking the abundance and character of magnetofossils to ancient biogeochemistry

contrasting sulfur geochemistry and fe al and mo al ratios across the last oxic to anoxic transition in the cariaco basin venezuela an abrupt transition from oxic to anoxic sulfidic euxinic marine bottom waters occurred in the cariaco basin in response to increasing productivity resulting from the late pleistocene post glacial rise in sea level and corresponding increase in surface water nutrient availability the microlaminated sediments of the euxinic interval which span the last f14 5 ky suggest a predominance of water column syngenetic pyrite formation based on 1 high pyrite sulfur spy concentrations in the surficial sediment layers 2 values for degree of pyritization dop that generally do not increase appreciably with increasing burial 3 ratios of total iron fet to al that are elevated above the continental baseline recorded in the underlying oxic sediments and 4 spy isotope trends that largely mimic the d 34 shsof the modern water column intermediate dop values in the microlaminated deposits and fet al ratios that are slightly above continental levels indicate an iron reservoir controlled by scavenging during syngenetic pyrite formation in combination with intermediate rates of fe bearing siliciclastic accumulation as predicted from the relative rates of siliciclastic delivery fet al and dop data lie between end member values observed in the modern black sea as viewed broadly fet al and dop relationships in euxinic sediments reflect the balance between syngenetic fe scavenging and temporal and spatial gradients in siliciclastic input pyrite concentrations are generally low in the underlying oxic marine deposits because of limitations in the supply of organic carbon corg however the upper 80 cm of the fe rich corg poor bioturbated sediment show evidence for a strong diffusional hsoverprint from the overlying fe limited euxinic marine environment this post glacial transition manifests in pyrite overprints that are strongly 34 s depleted relative to those in restricted presently euxinic marine settings elsewhere in the world such as the black sea where the sedimentary sequence spanning the last glacial interglacial transition begins with a shift from freshwater to corg poor oxic marine deposition and thus dominantly sulfate diffusion trends for mo al ratios in the microlaminated sediments suggest that mo is enriched by roughly two orders of magnitude above the continental levels recorded in the oxic deposits organic matter plays a role by enhancing hsproduction and or by providing a substrate for mo scavenging significant mo enrichment via diffusion into the upper portion of the bioturbated zone was not observed despite hs rich pore waters as recorded in the heavy iron sulfide overprint we have

gold and native copper in supergene sulphides from the mid atlantic ridge in 1985 black smokers and massive sulphide deposits were discovered in the tag hydrothermal field in the rift valley of the mid atlantic ridge near latitude 26 08 n ref 1 sulphide samples from chimneys and mounds were recovered by dredging at depths between 3 620 and 3 670 m mineralogical and chemical analyses of the samples reveal 1 primary unaltered zn fe cu sulphides containing 0 8 4 0 p p m au 0 02 0 12 oz per ton and 2 secondary cu rich sulphides with native copper formed by supergene alteration of primary cu fe sulphides containing up to 16 4 p p m au 0 48 oz per ton as free native gold this is the first reported occurrence of secondary enrichment of gold and copper in recent submarine sulphides the high gold grades and native copper associated with secondary cu sulphides resemble occurrences in some supergene gossans overlying ancient massive sulphide deposits on land2

micro environmental controls on biomineralization superficial processes of apatite and calcite precipitation in quaternary soils roussillon france calcium hydroxyapatite and calcite precipitates around bacteria were observed in 2 week old alluvial topsoil roussillon area se france this observation prompted a laboratory study of ca2 and po43 incorporation into hydroxyapatite and ca2 into calcite mediated by bacteria using similar topsoil material but free from apatite and calcite subsamples were prepared using three different grain sizes and experiments were undertaken using sucrose and different contents of ca2 and po43 mineralization experiments proceeded over 5 days calcium and po43 sorption onto clay influenced the ca p ratio in the solutions hydroxyapatite and calcite precipitation only occurred in unsterilized samples the presence of clay minerals promoted biomineralization

bacteria as nucleation sites for authigenic minerals in a metal contaminated lake sediment abstract sediment samples contaminated with metals arising from mine tailings drainage were obtained from lower moose lake in the onaping region near sudbury ontario canada the samples were examined by electron microscopy selected area electron diffraction and energy dispersive x ray spectroscopy individual bacterial cells and their remains were prominent as nucleation sites for both metal sulfides and a complex polymorphic fe al silicate the principal metal sulfide species associated with the bacteria were amorphous mackinawite fes 1 x and microcrystalline millerite nis trace amounts of cu and zu were also detected in some of the sulfide precipitates at least two structural forms of the fe al silicate were present and energy dispersive x ray spectroscopy point analyses revealed corresponding differences in chemical composition poorly ordered limonitic clay type phases had a granular morphology and contained less fe than well developed crystalline material which generated hexagonal diffraction patterns with reflections d 4 60 and 2 55 characteristic of an interstratified chamositic clay

geomorphological processes and frozen ground conditions in elephant point livingston island south shetland islands antarctica abstract elephant point is an ice free area in the sw corner of livingston island maritime antarctica the retreat of rotch dome glacier during the holocene has exposed a land area of 1 16 km2 up to 17 3 of this surface has become ice free between 1956 and 2010 a detailed geomorphological mapping of this ice free environment was conducted in late january 2014 a wide range of active periglacial landforms show that periglacial processes are widespread from the glacier to the coast four different geomorphological areas are identified proglacial environment moraine complex bedrock plateaus and marine terraces in situ measurements of the thawed soil depth show evidence of the widespread frozen ground conditions in the area field observations of permafrost exposures suggest that these frost conditions may be related to a soil permafrost regime almost down to sea level the activity of penguin colonies and elephant seals has created minor geomorphological features in the raised marine terraces here several archaeological sites related to early human colonization of antarctica were also found in natural shelters

post caldera evolution of deception island bransfield strait antarctica over holocene timescales abstract the study of palaeoclimatic changes in fast warming regions can contribute to the understanding of the forcing mechanisms responsible for the global changes that are presently happening deception is an active volcanic island in the bransfield basin that has a complex history strongly influenced by both magmatic and tectonic processes however without accurate information on the distribution of melt depth of sediments and holocene timescales of its volcanic eruptions the models for the post caldera evolution of deception island are poorly constrained although this region has undergone severe environmental changes due to recent eruptions hindering the location of potential study areas of paleo volcanic eruptions it is still possible to reconstruct post caldera evolution at a local scale employing analyses such as radiocarbon dating stable carbon and nitrogen isotopic compositions and particle size distributions in subsoil horizons we have studied the coastal areas of whalers bay and between wensleydale beacon and cross hill to identify the major periods of alluvial sedimentation on deception island whalers bay was influenced by a large amount of moving water generated by ice melting the coastal location of both sampling sites contributes to preserve the sedimentation history in their soil profiles despite the severe environmental changes due to recent eruptions our findings indicate that from approximately 13 to 5 cal kyr bp the accumulation of organic matter was stable and the landforms were not altered after that time post caldera eruptions occurred melting the glacier and consequently flooding surficial soil layers with mud these changes are consistent with old 14 c ages for subsoil organic matter and therefore with the occurrence of intense cryogenic disturbance processes

seismic image and origin of the changbai intraplate volcano in east asia role of big mantle wedge above the stagnant pacific slab abstract we determined p wave tomography of the crust and upper mantle under the changbai volcanic area in northeast asia by using 289 318 arrival time data from 4802 local earthquakes and 9599 teleseismic events a prominent low velocity anomaly is clearly imaged in the crust and upper mantle down to about 410 km depth beneath the changbai volcano a broad high velocity anomaly is revealed in the mantle transition zone and deep earthquakes occurred actively there suggesting that the subducting pacific slab is stagnating in the mantle transition zone under east asia our results suggest that the formation of the changbai and other intraplate volcanoes in northeast asia is related to the upwelling of hot and wet asthenospheric materials in the big mantle wedge above the stagnant pacific slab hence the active intraplate volcanoes in northeast asia are not hotspots related to deep mantle plumes but are caused by plate tectonic processes in the upper mantle

se minerals in the continental and submarine oxidation zones of the south urals volcanogenic hosted massive sulfide deposits a review abstract the occurrence of se minerals in continental and submarine oxidation zones of the south urals volcanogenic hosted massive sulfide deposits is reviewed clausthalite naumannite and se bearing galena occur both in continental and submarine oxidation zones native selenium tiemannite and se bearing secondary copper sulfides sulfosalts and chalcopyrite are found only in the continental oxidation zone whereas te bearing naumannite bohdanowiczite and se bearing roquesite are identified in the submarine oxidation zone the se minerals more often occur in the lower parts of the continental and submarine oxidation zones secondary copper enrichment subzone and the bottom part of the leaching subzone in the continental supergene zone the se rich sulfur sand subzone mostly contains se in forms of native phase and various selenides rare se minerals are found in continental gossans iron cap and submarine gossanites ferruginous products of complete submarine oxidation of massive sulfide ores mixed with hyaloclasts and carbonates as shown by thermodynamic calculations presence of selenides in the lower part of the oxidation zone is due to their stability under more oxidizing conditions than the corresponding sulfides at low temperature the formation of selenides and se bearing sulfides in assemblage with fe iii oxyhydroxides can be a result of low activity of reduced s when se successfully competes with s for the formation of the chalcogenides the formation of selenides in the upper part of the oxidation zone is probably related to local redox barrier which is formed due to vital functions of living organisms the primary massive sulfide ores with se pb ag and hg bearing high temperature chalcopyrite and another high temperature primary sulfides and low temperature colloform pyrite are source of the selenium and metals for supergene selenides and se bearing chalcogenides

solifluction rates processes and landforms a global review abstract field data on the rates of solifluction and associated parameters are compiled from the literature in an attempt to evaluate factors controlling the spatial variability in solifluction processes and landforms with special attention on the climate solifluction relationship the analyzed data originate from 46 sites over a wide range of periglacial environments from antarctic nunataks to tropical high mountains solifluction broadly defined as slow mass wasting resulting from freeze thaw action in fine textured soils involves several components needle ice creep and diurnal frost creep originating from diurnal freeze thaw action annual frost creep gelifluction and plug like flow originating from annual freeze thaw action and retrograde movement caused by soil cohesion the depth and thickness of ice lenses and freeze thaw frequency are the major controls on the spatial variation in solifluction processes near the warm margin of the solifluction affected environment diurnal freeze thaw action induces shallow but relatively rapid movement of a superficial layer 5 10 cm thick on average often creating the thin stone banked lobes typically seen on tropical high mountains in addition to diurnal movement annual frost creep and gelifluction may occur on slopes with soil climates of seasonal frost to warm permafrost dislocating a soil layer shallower than 60 cm at a rate of centimeters per year and eventually producing medium size solifluction lobes in high arctic cold permafrost regions two sided freezing can induce plug like flow of a soil mass 60 cm or thicker the correlation between process and landform suggests that the riser height of lobes is indicative of the maximum depth of movement and prevailing freeze thaw type climate change may result in new different ground freezing conditions thereby influencing the surface velocity and maximum depth of soil movement soil moisture and topography also control solifluction high moisture availability in the seasonal freezing period enhances diurnal freeze thaw action and subsequent seasonal frost heaving the latter contributes to raising the moisture content of the thawed layer and promotes gelifluction during the thawing period the slope angle defines the upper limit of the surface velocity of solifluction a diagram correlating the potential frost creep with the actual surface velocity permits an inter site comparison of the relative magnitude of solifluction components physically based modelling of periglacial slope evolution requires synthetic and more detailed field monitoring and laboratory simulations of solifluction processes

ophiolites as faithful records of the oxygen isotope ratio of ancient seawater the solund stavfjord ophiolite complex as a late ordovician example

advances in permafrost and periglacial research in antarctica a review recently the research on permafrost periglacial morphology and processes had a great stimulus especially from the international polar year permafrost areas of continental antarctica with its extreme dry and cold environment can be considered an analog of extraterrestrial landscapes like those on mars but also preserve much paleoclimatic information of this crucial part of the global climatic system on the other hand maritime antarctica is one of the areas of the world currently affected by the greatest air warming and provides a unique opportunity to understand the impacts of climate change on permafrost and its related ecosystems despite the significant recent progress some gaps on permafrost distribution still remain as the network for permafrost and active layer monitoring needs further enlargement and better standardization ground ice its age and stability over time need further investigation as well as the role of living organisms on the weathering processes within the cryotic rocks the landscape evolution of continental antartica could be improved providing potential implications also for a better understanding and modeling of life and landscape evolution of other planets

ferruginous and manganiferous haloes around massive sulphide deposits of the urals proximal brecciform ferruginous and manganiferous rocks related to vms deposits of the urals are subdivided into jasperites gossanites and umbers in addition to thin bedded jaspers and cherts the coherence of host rock composition and mn fe fertility of the sediments have been established fe poor pink hematitic and gray sulphidic chert are typical of the felsic class of vms deposits in contrast the contents of fe vary from high to moderate in ferruginous rocks enclosed in basaltic units associate with vms deposits fe and mn rich ferruginous rocks and umbers occur in association with limestones and calcareous sedimentary rocks in both types of volcanic sequences a common feature of jasperites and umbers is the abundance of replacement textures of hyaloclastites and carbonates by hematite and silica in addition replacement of clastic sulphides by hematite and magnetite is a characteristic genetic feature of gossanites all of these sedimentary rocks are accompanied by pseudomorphs of hematite and quartz formed after bacterial filaments the abundance of replacement textures are supportive of the halmyrolysis model in addition to hydrothermal sedimentary and sub seafloor hydrothermal replacement theories study of chemical zonation of altered hyaloclasts shows depletion of their rims not only in mobile na k mg but also in immobile al ti and ree whereas si and fe are concentrated in situ the halmyrolysis model presented here involving organic rich calcareous hyaloclastic sediments resolves the problem of subtraction of al ti ree and other elements which are commonly immobile under hydrothermal conditions the evolution of the halmyrolysis process from acidic reducing to alkaline oxidized conditions infers a possible range in transformation from fe ii mg smectites to fe silicates and fe si oxides as precursors of brecciform jasperite and thin bedded jasper the higher acidic initial stage of gossanite formation seems to be required for oxidation of organic matter and or pyrite the acidic condition facilitates the temporal preservation of immobile elements al ti ree in immature chlorite hematite gossanites another peculiarity of the gossanite forming processes is the likely sorption of p u and v by iron hydroxides displacing sulphides the general evolution of all ferruginous sediments results in complete fe 2 oxidation and silicification accompanied by subtraction of other elements the vertical diagenetic differentiation leads to concentration of mn carbonates silicates and oxyhydroxides into the tops of jasperite and gossanite layers mn oxyhydroxides scavenge positively charged hydrated cations like co and ni near vent bacterial communities may activate the processes of volcanic glass and sulphide degradation the proposed processes of halmyrolysis followed by silicification in situ may resolve the enigma of silica rich sediment formation in a silica undersaturated ocean the discrimination between gossanite and jasperite is useful for elaboration of new criteria for local exploration of vms and mn deposits halo dispersion of gossanites covering an area about two to three times that of the massive sulphide deposit is a good vector for ore body discovery proximal gossanites can be differentiated from jasperites by presence of relic sulphide clasts or elevated contents of chalcophile elements cu fe zn pb bi te as sb ba noble metals au ag and distinct ree patterns with la and eu positive anomalies the development of halmyrolysis and biomineralization models merit further elaboration and testing in on going research in order to add or revise theories of iron and manganese deposit formation 2012 elsevier b v

enhanced bedrock weathering in association with late lying snowpatches evidence from livingston island antarctica an indication of the extent of weathering on different aspects of rock outcrops on livingston island antarctica was obtained by means of a schmidt hammer a cone indenter and measurement of weathering rind thickness results show that weathering particularly chemical weathering is enhanced on the lee side of outcrops where snow accumulates as a result of prolonged wetting by the melting snow rock moisture and temperature data indicate that the south facing snow accumulation side of obstacles have high rock moisture levels and maintain relatively high temperatures whilst chemical weathering is greater on the leeward side of outcrops mechanical processes are greater on the windward side the presence of late lying snow thus appears to exert a strong influence on weathering

electrical resistivity structure at the northern margin of the tibetan plateau and tectonic implications 1 the ene wsw striking altyn tagh fault atf and the wnw ese trending western qilian mountains define the northern margin of the tibetan plateau new magnetotelluric data were collected along three profiles crossing the eastern section of the atf and the southern qilian mountains the basic sounding bandwidth ranged from 0 003 to 7000 s the transverse electric and transverse magnetic mode data sets were inverted into resistivity sections using a conventional two dimensional 2d inversion code and data at periods of 0 3333 5464 s were inverted using a commonly employed three dimensional 3d code the 3d results constrain the interpretation of the 2d models and the final interpretative resistivity models show that lithospheric structures are spatially variable along the atf and across southern qilian in profiles across the atf the main fault is imaged as a vertical resistivity boundary and the high resistivity body in the western profile extends about 15 km deeper than the corresponding body in the eastern profile positive flower structures are apparent in the western profile but are only weakly visible in the eastern profile these observations suggest that the depth of the atf is spatially variable mantle resistivity images indicate a relatively cold and rigid tarim lithosphere which is consistent with a geodynamic model of oblique subduction of the tarim basin below the atf a high resistivity body in the crust of southernmost qilian indicates a huge thick skinned structure low resistivity bodies at the crust mantle boundary south of the main atf are presumed to form a weak layer beneath northern tibet

preservation of 3 4 3 5 ga microbial biomarkers in pillow lavas and hyaloclastites from the barberton greenstone belt south africa exceptionally well preserved pillow lavas and inter pillow hyaloclastites from the barberton greenstone belt in south africa contain textural geochemical and isotopic biomarkers indicative of microbially mediated alteration of basaltic glass in the archean the textures are micrometer scale tubular structures interpreted to have originally formed during microbial etching of glass along fractures textures of similar size morphology and distribution have been attributed to microbial activity and are commonly observed in the glassy margins of pillow lavas from in situ oceanic crust and young ophiolites the tubes from the barberton greenstone belt were preserved by precipitation of fine grained titanite during greenschist facies metamorphism associated with seafloor hydrothermal alteration the presence of organic carbon along the margins of the tubes and low d 13 c values of bulk rock carbonate in formerly glassy samples support a biogenic origin for the tubes overprinting relationships of secondary minerals observed in thin section indicate the tubular structures are pre metamorphic overlapping metamorphic and igneous crystallization ages thus imply the microbes colonized these rocks 3 4 3 5 ga although the search for traces of early life on earth has recently intensified research has largely been confined to sedimentary rocks subaqueous volcanic rocks represent a new geological setting in the search for early life that may preserve a largely unexplored archean biomass d 2005 elsevier b v all rights reserved

p wave tomography and origin of the changbai intraplate volcano in northeast asia abstract we present the first seismic image of the upper mantle beneath the active intraplate changbai volcano in northeast asia determined by teleseismic travel time tomography the data are measured at a new seismic network consisting of 19 portable stations and 3 permanent stations our results show a columnar low velocity anomaly extending to 400 km depth with a p wave velocity reduction of up to 3 high velocity anomalies are visible in the mantle transition zone and deep focus earthquakes occur at depths of 500 600 km under the region suggesting that the subducting pacific slab is stagnant in the transition zone as imaged clearly by global tomography these results suggest that the intraplate changbai volcano is not a hotspot like hawaii but a kind of back arc volcano related to the deep subduction and stagnancy of the pacific slab under northeast asia

hydrothermal oxide and nontronite deposits on seamounts in the eastern pacific deposits of fe oxide mud nontronite and fe mn crusts were sampled from the summits of two seamounts in the eastern pacific where low temperature 0 15 c hydrothermal fluids are issuing the deposits consist of x ray amorphous fe oxyhydroxide and are rich in fe 43 wt contain minor si and p 4 and 3 5 respectively and have very low mn 0 01 and other trace element contents other deposits where no current hydrothermal activity was observed consist of mud and crusts composed of amorphous material and poorly crystalline hematite goethite and smectite these deposits have slightly higher mn up to 2 and other trace element contents the mineralogical and chemical differences between the active and inactive deposits and crusts are interpreted to be due to recrystallization and contamination with detrital biogenic hydrogenous and possibly hydrothermal sulfide material nontronite deposits capped by fe mn oxides were sampled from one of the seamounts these deposits have compositions similar to other seafloor nontronite deposits and formed at low temperatures 30 c during mixing of low temperature hydrothermal fluids with seawater the oxide deposits consist almost entirely of long delicate filaments remarkably similar in morphology to genera of fe oxidizing bacteria such bacteria were probably important in catalyzing the oxidation and precipitation of iron from hydrothermal fluids on the seamounts the occurrence of nearly identical filament rich oxide deposits on two widely separated seamounts suggests that this type of deposit may be common on seamounts but previously unrecognized

periglacial processes and landforms in the south shetland islands northern antarctic peninsula region abstract periglacial processes and landforms together with the presence of permafrost are among the most relevant geomorphological elements in the northern antarctic peninsula region their distribution affects the hydrology and has consequences for the ecosystems of the ice free areas in this paper a compilation of the different types of periglacial landforms and processes occurring in the south shetland islands is carried out and their spatial distribution is analysed furthermore the relationships of the periglacial landforms with local conditions and permafrost distribution have been taken into account a total of thirty three types of periglacial landforms were identified and considered in this work patterned ground and stone fields are the most common periglacial landforms which are located within a wide altitudinal range and mainly on platforms field studies aerial photograph and satellite imagery interpretation were implemented to produce detailed maps from ten areas with different geological geomorphological and relief characteristics including the largest and most relevant ice free areas within the archipelago showing the presence and spatial distribution of periglacial landforms this work shows that the periglacial environment primarily conditioned by the regional climatic conditions has a great diversity in the studied region and that the distribution of the periglacial landforms is also related to local relief and geomorphological characteristics lithology hydrogeology and presence of permafrost where altitude plays an important role periglacial phenomena are widespread above 10 m a s l and are especially active on slopes and platforms between 30 and 100 m a s l the spatial distribution of periglacial landforms helps to identify the presence of permafrost that is dominant above 25 30 m a s l and more than 70 of the surface is occupied by active layer related landforms