reduction in northward incursions of the south asian monsoon since 1400 ad inferred from a mt everest ice core 1 a highly resolved mt everest ice core reveals a decrease in marine and increase in continental air masses related to relatively high summer surface pressure over mongolia and reduction in northward incursions of the summer south asian monsoon since 1400 ad previously published proxy records from lower sites south of the himalayas indicate strengthening of the monsoon since this time these regional differences are consistent with a south north seesaw in convective activity in the asian monsoon region and reflect a southward shift in the mean summer position of the monsoon trough since 1400 ad the change in monsoonal circulation at 1400 ad is synchronous with a reduction in solar irradiance and the onset of the lia this demonstrates a hemispheric scale circulation reorganization at this time and the potential for future large shifts in monsoonal circulation

temporal variations of accumulation and temperature during the past two centuries from belukha ice core siberian altai 1 the temporal variation of accumulation and temperature in the siberian altai were investigated using a 86 m long ice core from belukha glacier 49 48 26 n 86 34 43 e 4062 m a s l covering the time period 1816 to 2001 as temperature sensitive parameters the melt percent profiles and the stable oxygen isotopes 18o were evaluated representing summer season and march to november temperatures respectively the accumulation record showed no long term trend and only minor deviations of limited duration from the accumulation average of 0 5 m water equivalent y weq y were observed in contrast the two temperature proxies indicate a strong warming trend in the order of 1 6 0 4 c and 1 7 1 1 c over the last century inferred from melt percentages and the 18o record respectively and 2 5 1 7 c since the mid 19th century inferred from the 18o record this reflects an amplified regional climate response following the little ice age lia as compared to the northern hemisphere average most probably caused by the strong continentality of the siberian altai region the sudden onset of large melt features since 1988 indicates that the upper reaches of belukha glacier are experiencing a change from the recrystallization to the cold infiltration zone that now allows for multiannual percolation of meltwater implying that the conservation of accumulation and geochemical properties including those providing temperature proxies is currently endangered

transport of atmospheric impurities over the qinghai xizang tibetan plateau as shown by snow chemistry abstract chemical records were recovered from samples collected from snow pits over two transects s n and se nw across the qinghai xizang tibetan plateau the records show that the flux of major ions in the regions to the north of mt tanggula is on the average 6 30 times higher than that of the regions to the south and 0 6 5 times higher than regions to the southeast it appears that mt tanggula provides a barrier to continental dust transported across the plateau from the north and to marine aerosols transported from the southeast the spatial patterns of snow chemistry as well as the total suspended particle tsp distribution along the northern qinghai xizang highway demonstrate that continental dust originates mainly from the deserts to the north while monsoon sources of moisture exert greater influence on snow chemistry on the southern part of the plateau seasonal variations of the major ions were also examined in a firn core drilled at a height of 7000 m on the dasuopu glacier and in a snow pit from the meikuang glacier eastern kunlun the choice of a high altitude site at dasuopu and the sampling season before snowmelt at meikuang avoided post depositional modification processes mainly the elution effect of meltwater thus guaranteeing the reliable recovery of the distribution of impurities in different seasons the peak of the impurities appear at dasuopu during the spring and at meikuang in the winter spring coinciding with the asian dust season however the amplitude of the seasonal variations at meikuang is much higher than at dasuopu ph values at the dongkemadi glacier are greater than 6 but at the dasuopu glacier himalayas they range between 4 and 7 5 the liquid conductivity lc from dongkemadi is positively correlated with the ph while at dasuopu lc is positively correlated with ph when ph is below 6 and negatively correlated with ph when it is greater than 6 this implies that during august to september the himalayan range is a transition zone between the transportation of continental dust and marine aerosols

analysis of the bedding landslide due to the presence of the weak intercalated layer in the limestone analysis and research results show that the sliding plane of jiudingshan landslide is along the weak intercalated layer clay filled in the limestone and the sliding block is separated by the tension crack on the slope crest the earlier study results show that for the rough ups and downs structural plane when i is greater than 2 0 the shear strength of the structural surface is intensely close to the strength of the filling by the earlier theory this failure must be through the clay filling in this study the failure is back analyzed and the shear strength of the infilling is tested by the laboratory direct shear tests for which samples were retrieved in the field the failure cannot be explained by the laboratory results of shear strength parameters to simulate the field conditions the real strength parameters of sliding surface are measured by the in situ shear tests for the weak intercalated layer by the in situ tests it is shown that the failure initiates along the contacts between the clay infilling and the limestone boundaries but not through the clay itself though the contact surface is the interface of the clay limestone the cohesion is not 0 and it is not negligible too

vent type taxa in a hydrocarbon seep region on the louisiana slope recent discoveries on the northern gulf of mexico continental slope have altered our understanding of biological and chemical processes occurring in the deep ocean a biological community of hydrothermal vent type organisms was recently discovered at the base of the florida escarpment1 where the fauna are apparently nourished by hydrogen sulphide rich hypersaline water seeping out onto the sea floor dense colonies of deep living chemosynthetic benthic organisms were first discovered during investigations of warm water anomalies along the axis of the galapagos rift in the pacific ocean in 19772 4 and this first discovery of clusters of clams tube worms and other filter feeders in the immediate proximity of warm water vents has been followed by the discovery of a number of other hydrothermal vent sites for example guaymas basin east pacific rise at 21 n the dense population assemblages at these sites are apparently restricted to small areas of the ocean floor where hydrogen sulphide rich water is escaping from spreading centres but the florida escarpment discovery indicates that these communities can also exist on passive margins here we report the discovery of dense biological communities associated with regions of oil and gas seepage on the louisiana continental slope these communities of large epi and infaunal organisms are similar to those associated with the vents of the pacific and the hypersaline brine seeps of the florida escarpment carbon isotope analyses suggest that these communities are chemosynthetic and derive their energy from hydrogen sulphide and or hydrocarbons similar communities may be widely distributed on the sea floor in other oil producing regions of the ocean

highly isotopically depleted isoprenoids molecular markers for ancient methane venting abstract we propose that organic compounds found in a miocene limestone from marmorito northern italy are source markers for organic matter present in ancient methane vent systems cold seeps the limestone contains high concentrations of the tail to tail linked acyclic c20 isoprenoid 2 6 11 15 tetramethylhexadecane crocetane a c25 homolog 2 6 10 15 19 pentamethylicosane pme and a distinctive glycerol ether lipid containing 3 7 11 15 tetramethylhexadecyl phytanyl moieties the chemical structures of these biomarkers indicate a common origin from archaea their extremely 13c depleted isotope compositions 13c 108 to 115 6 pdb suggest that the respective archaea have directly or indirectly introduced isotopically depleted methane derived carbon into their biomass we postulate that a second major cluster of biomarkers showing heavier isotope values 13c 88 is derived from sulfate reducing bacteria srb the observed biomarkers sustain the idea that methanogenic bacteria in a syntrophic community with srb are responsible for the anaerobic oxidation of methane in marine sediments marmorito may thus represent a conceivable ancient scenario for methane consumption performed by a defined two membered bacterial consortium 1 archaea that perform reversed methanogenesis by oxidizing methane and producing co2 and h2 and 2 srb that consume the resulting h2 furthermore the respective organic molecules are unlike other compounds tightly bound to the crystalline carbonate phase the marmorito carbonates can thus be regarded as cold seep microbialites rather than mere authigenic carbonates

methane derived authigenic carbonates formed by subduction induced pore water expulsion along the oregon washington margin authigenic magnesian calcite dolomite and aragonite are precipitated in the uppermost terrigenous sediments of the washington oregon accretionary prism by subduction induced dewatering these distinctive carbonates are methane derived and occur at sites of concentrated pore water expulsion unique biologic communities that subsist at least indirectly on methane suess et al 1985 are also found at some of these sites the methane which is dominantly biogenic is carried to the uppermost sediments of the prism by fluids and is oxidized by sulfate reducers before being incorporated into a carbonate cement carbonate precipitation occurs below the oxic layer probably no deeper than several centimetres to a few metres below the seabed cementation may be induced by three factors 1 increased carbonate alkalinity resulting from microbial sulfate reduction 2 decreased co 2 solubility resulting from a pressure decrease when the pore water escapes the prism and or 3 the addition of ca 2 and mg 2 ions from sea water near the sediment water interface the convergent margin setting engenders precipitation of authigenic carbonates in several ways compressive stresses induce anomalously rapid compaction and dewatering rates and they may cause overpressuring in migrating pore water thereby delaying precipitation of carbonates until pressure is released near the sediment water interface structural deformation of the accretionary prism creates pathways such as fault zones secondary fracture porosity and dipping permeable layers often exposed by mass movement for efficient advection and expulsion of methane enriched pore water these characteristic conditions which lead to the precipitation of methane derived carbonates may be found at other convergent margins

association between atmospheric circulation patterns and firn ice core records from the inilchek glacierized area central tien shan asia 1 glacioclimatological research in the central tien shan was performed in the summers of 1998 and 1999 on the south inilchek glacier at 5100 5460 m a 14 36 m firn ice core and snow samples were collected and used for stratigraphic isotopic and chemical analyses the firn ice core and snow records were related to snow pit measurements at an event scale and to meteorological data and synoptic indices of atmospheric circulation at annual and seasonal scales linear relationships between the seasonal air temperature and seasonal isotopic composition in accumulated precipitation were established changes in the 18o air temperature relationship in major ion concentration and in the ratios between chemical species were used to identify different sources of moisture and investigate changes in atmospheric circulation patterns precipitation over the central tien shan is characterized by the lowest ionic content among the tien shan glaciers and indicates its mainly marine origin in seasons of minimum precipitation autumn and winter water vapor was derived from the arid and semiarid regions in central eurasia and contributed annual maximal solute content to snow accumulation in tien shan the lowest content of major ions was observed in spring and summer layers which represent maximum seasonal accumulation when moisture originates over the atlantic ocean and mediterranean and black seas

failure mechanism and stabilization of a basalt rock slide with weak layers abstract multiple slides of rock slopes with dip weak layers have occasionally occurred in chinese roadway engineering representing a very complex problem associated with roadway excavation unfortunately the failure mechanisms of such slopes are not clearly investigated prior to excavation thus leading to expensive remedial work installed after the significant deformative phenomena occurred furthermore pre reinforced piles have not received enough attention to be used to stabilize the slopes during the excavation process which enables the slope movements this paper therefore aims to explore the failure mechanisms of a basalt rock slide with dip weak layers and analyse the impacts of pre reinforced piles on the slope stability field investigations laboratory tests and in situ deformation monitoring are conducted slope stability before and after excavation is analyzed using the finite element and limit equilibrium analysis methods respectively the outcomes of the analyses reveal that excavation and the presence of dip weak layers are the main contributory factors to the rock slide the failure surface of the slope varies with increases in excavation rather than always occurring along the revealed weak layers the instability appears to be multiple translational slides additionally a finite element analysis for the slope pre reinforced with row piles during different stages of excavation is conducted based on the study results the pre reinforced pile is crucial for the slope stability and the impact of pile position should be prudently considered in design

methane related carbonate cements in pockmarks of the north sea abstract some pockmarks on the norwegian continental shelf contain patches of cemented sediment that can provide hardgrounds attractive to a variety of benthonic organisms detailed examination of a sandstone sample from a pockmark in norwegian block 25 7 in the north sea has revealed the presence of mg calcite and aragonite cements some of the latter forming botryoids all cement types are characterized by extremely light carbon isotopic compositions with a mean 13c value of 56 1 pdb which shows that the cements contain carbonate produced by oxidation of biogenic methane oxidation occurred in both the oxic and anoxic diagenetic zones trace amounts of interstitial methane mean 13c 40 8 and higher hydrocarbon gases up to c5 with a c1 cn ratio of 0 855 0 874 in the pockmark sediments indicate that some thermogenic methane may be mixed with the biogenic gas

hydrothermal sulfide and oxide deposits on seamounts near 21 n east pacific rise hydrothermal deposits were sampled by submersible from the calderas and summit benches of two seamounts 20 and 30 km west of the east pacific rise at 21 n the deposits document a wide variety of off axis hydrothermal activity including samples from the interiors of seafloor sulfide deposits in contrast to most mid ocean ridge deposits sulfide deposits on green seamount are rich in si fe and cu are poor in zn and contain abundant quartz sulfide chimneys grew by quenching of hydrothermal fluids and deposition of walls of colloform pyrite marcasite zn sulfide and minor galena whereas coarse grained pyrite and chalcopyrite were deposited at higher temperatures 250 c in chimney interiors as chimney walls grew outward into sea water increased temperatures in the inner walls resulted in recrystallization to pyrite and deposition of pyrite and chalcopyrite in pore space cooling in the outer portions of chimneys caused deposition of opal at temperatures of about 80 170 c as chimneys coalesced and opal rich material was heated in the interiors of sulfide edifices opal was recrystallized to chalcedony and quartz faulting has exposed the interiors of sulfide deposits where further recrystallization and deposition of chalcopyrite and quartz occurred at temperatures of 230 320 c clogging of chimneys changes in flow paths and cooling of the deposits led to the deposition of late mixed layer illite smectite iron sulfides fe poor sphalerite opal and barite the sulfide deposits formed over a time span of at least 140 000 to 70 000 yr ago probably coincident with caldera and pit crater formation the ages of the sulfide deposits provide constraints on the last volcanic and tectonic activity and they also suggest that it took a maximum of 260 000 yr for the seamount to reach its present height red seamount is presently hydrothermally active and deposits consisting predominantly of amorphous fe oxyhydroxide are forming on small pillow cones in the caldera at temperatures of 10 15 c hydrothermal nontronite deposits capped by mn oxide crusts cover much of the southern summit bench of red seamount and formed at temperatures of around 30 c iron rich talc and sulfide grains in nontronite provide evidence of former high temperature activity and suggest that a sulfide deposit is present nearby

a lower jurassic heteroporid bryozoan and associated biota turnagain lake british columbia late early jurassic heteroporid bryozoa occur in arenaceous carbonates near turnagain lake north central british columbia the occurrence of heteropora tipperi n sp marks the first documentation of early jurassic cyclostome bryozoa in north america the associated fauna comprising the ammonite harpoceras the foraminifer reinholdella and the pelecypod weyla establish the age as early toarcian other associated biota include an endolithic green alga e which is demonstrated to have a commensal relationship with h tipperi n sp sedimentologic and biotic data from the host strata point to a shallow temperate high energy normal marine environment

a high resolution atmospheric dust record for 1810 2004 a d derived from an ice core in eastern tien shan central asia centennial scale high resolution records of atmospheric dust conditions are rare in the arid and semiarid regions of central asia limiting our understanding of the regional climate and environmental changes and their potential driving forces in this paper we present an annually resolved atmospheric dust record covering the period of 1810 2004 a d reconstructed from an ice core retrieved at 4512 m above sea level from the miaoergou glacier in the eastern tien shan the time series of dust flux for the past 195 years shows three periods of relatively low values i e 1810 1829 a d 1863 1940 a d and 1979 2004 a d and two periods of relatively high values i e 1830 1862 a d and 1941 1978 a d spatial correlation analysis suggests possible regional factors controlling the dust flux including antecedent summer precipitation spring soil moisture and near surface wind speed in addition the miaoergou dust flux is closely associated with the winter index of the north atlantic oscillation nao over the past two centuries with high low dust periods coinciding with the negative positive phases of the nao the persistent relationship suggests that the nao may have been a key driver on dust flux change over the arid regions between the tien shan and kunlun mountains

why did ancient chemosynthetic seep and vent assemblages occur in shallower water than they do today cold seep communities have relatively low diversity are dominated by one or two taxa present in high density and high biomass in comparison with the surrounding fauna and are restricted to aphotic habitats their associated heterotrophic fauna are usually distinctive from the fauna of their surroundings in contrast a more commonplace chemoautotrophically based community occurs in shallow photic habitats the associated heterotrophic fauna includes many of the species typical of the surrounding communities and typically dominates abundance whereas the species with chemoautotrophic symbionts dominate biomass all modern seep assemblages are deeper than 550 m many fossil seep assemblages occurred in water as shallow as the mid shelf 200 m in contrast communities where species with chemoautotrophic symbionts are biomass dominants but not numerical dominants are common in shallow waters at present but rarely reported in the geological record we suggest that the absence of cold seep communities on the continental shelf presently is due to a combination of predation and competitive exclusion by primary consumers limiting the presence of species dependent on chemoautotrophic symbionts we suggest that cold seep assemblages are more common at shelf depths in the fossil record for two reasons a the biases of preservation have accentuated their distribution by transforming communities where species with chemoautotrophic symbionts dominate by biomass but not numerically into cold seep appearing assemblages b the importance of predation pressure and oligotrophy has varied with decreased predation pressure accompanying increased oligotrophy favoring cold seep communities we suggest that the paucity of shallow water assemblages with species harboring chemoautotrophic symbionts as biomass dominants in the fossil record is based on the reliance of paleoecological analysis on numerical abundance data when energy flow analyses are required to identify these assemblages the distinctiveness of the fossil seep assemblage is intensified by taphonomic processes that bias the assemblage against small individuals and epifaunal species so that diversity declines the small heterotrophic component of the assemblage is significantly reduced and the epifaunal component is minimized the final assemblage is usually dominated by the better preserved large infaunal clams which perchance are also the species with chemoautotrophic symbionts in contrast preservation does not enhance the distinctiveness of these chemoautotroph harboring species in shallow water

analogue modeling of the collapse of non homogeneous granular slopes along weak horizons abstract in this study we use results of analogue models to investigate the effect of the dip location and thickness of a weak horizon on the stability failure kinematics and internal deformation of a granular slope the models are systematically designed to simulate the collapse of non homogeneous granular slopes by focusing on the spatial and temporal distribution of their internal deformation model results show that the presence of a weak horizon embedded within the granular slope has a significant influence on the granular failure which is accommodated through different generation pulses that successively decrease in volume however the dip and stratigraphic location of the weak horizon dictate whether the weak horizon play a role during the failure or not when the main failure surface is contained within a weak horizon the dip and thickness of the weak horizon have a positive effect on the displacement of the failure mass whereas a shallow located weak horizon causes larger displacement of the failure mass during the collapse of granular slopes in addition the collapse of granular slopes results in the formation of different generation normal faults and shortening structures folds and thrusts within the failure mass the first generation normal faults with a steep dip about 60 cut across the entire stratigraphy of the slope whereas the later generation normal faults with a gentle dip about 40 cut across the shallow units the distribution of these internal structures within the failure mass is affected significantly by the dip location and thickness of the weak horizon

correlation between the oxygen isotope record from dasuopu ice core and the asian southwest monsoon during the last millennium long high resolution proxy records are valuable for understanding asian southwest monsoon asm dynamics on decadal to centennial timescales a millennium long d 18 o ice core record from the central himalayas provides an opportunity to study the asm variability on decadal to centennial timescales the dasuopu ice core d 18 o record indicates that a relatively warm period corresponding with the medieval warm period lasted from ad 1140s to 1390s a notable warming trend is apparent from 1800s to 1990s and several cool periods occurred between ad 1010 1130s 1290 1330s 1400 1460s 1520s 1590 1630s 1740s and 1770 1790s comparisons with other high resolution monsoon proxy records from the arabian sea south oman and southern china reveal a high correspondence between temperature changes in the central himalayas and the asm variability during the last 1000 years a pronounced warming trend since ad 1670 coincides with an abrupt transition from a weak to a strong intensity of the asm the thermal conditions in the himalayas and on the tibetan plateau and associated glacial boundary conditions may have been predominantly responsible for variations of the asm intensity and for a latitudinal movement in the mean position of the itcz on decadal to centennial timescales r 2007 elsevier ltd all rights reserved

reconstruction of surface air temperature in a glaciated region in the western qilian mountains tibetan plateau 1957 2013 and its variation characteristics abstract based on the meteorological observations at three sites 4180 m 4550 m and 5040 m a s l in laohugou and the surrounding 7 national meteorological stations the long term surface air temperature of the glaciated region in the qilian mountains northeastern tibetan plateau during 1957 2013 was reconstructed the in situ air temperature observed at 4180 m during 1959 1961 was used to verify the reconstructed temperature series several approaches of multiple regressions were applied to select the optimal method in estimating the daily air temperature including the ordinary least square regression olsr stepwise regression sr principal component regression pcr and partial least squares regression plsr respectively according to root mean square error mean bias error and correlation coefficient olsr is selected as the optimal approach in the study region the reconstructed daily temperature correlates well with the synchronous observations and correlation coefficients are higher than 0 96 p p

temporal variations of mineral dust biogenic tracers and anthropogenic species during the past two centuries from belukha ice core siberian altai 1 in july 2001 a 140 m long ice core was recovered from the belukha glacier 49 48 26 n 86 34 43 e 4062 m a s l in the siberian altai the ion chemistry of the upper 86 m covering the last two centuries is characterized by biogenic emissions ammonium and formate aeolian dust calcium magnesium chloride and sodium and anthropogenic species sulfate nitrate and ammonium particularly high ammonium and formate concentrations indicate pronounced emissions from siberian forests the inferred fire frequency does not show a long term trend but distinct periods of enhanced activity sulfate has the highest industrial to preindustrial ratio and an anthropogenic contribution of more than 80 variations in this record reflect sulfur dioxide emissions in siberia and kazakhstan sulfate concentrations remained low until 1950 then sharply increased and peaked in the 1970s the decrease in the 1980s is attributed to the economic political and social crises and to the replacement of coal with gas rising nitrate concentrations since 1960 reflect traffic growth and enhanced fertilizer application increasing ammonium concentrations since the 1950s are attributable to population inflow in southern siberia with the associated enhancement of agricultural activity a nitrate peak of short duration in 1908 is thought to be the atmospheric signature from the tunguska event on 30 june 1908

ecologie des pseudobiohermes des terres noires jurassiques lies a paleo sources sous marines le site oxfordien de beauvoisin drome bassin du sud est france abstract pseudobioherms are fossiliferous calcareous bodies well exposed within jurassic calcareous shales of se france their genesis is unknown oxfordian psedobioherms of the outcrop of beauvoisin are studied here several kinds of results show that they are probably built at vent of submarine springs in a bathyal environment among their related fauna bivalves are thriving they show some remarkable analogies morphology growth distribution with some typical bivalves of recent springs hydrothermal vents or cold seeps like calyptogena isotopic composition of their shell exhibits a highly positive 13c and emphasizes this resemblance this suggests a chemosynthetic food supply through a bacterial symbiosis the whole fauna microfauna and macrofauna was inventoried within pseudobioherms and their close and far environment a comparative paleoecological study has been carried out to evaluate the faunal anomaly shown by a selected pseudobioherm two contemporaneous sections one close to this pseudobioherm and one other in a distant area without pseudobioherms have been studied in detail all taphonomic disturbances which are able to alter data have been carefully studied the paleobiocoenose suggests a slightly higher environmental stability because of an additional food supply within an environment usually less favorable it also suggests some permanency of spring activity the impact of the supposed springs on the benthic fauna is localized and slightly preserved through fossil fauna it mainly expresses itself in bivalves and organisms able to eat them crustacean cephalopods considering these various observations and after a critical comparison with characteristics and geological setting of recent submarine springs a model is suggested to understand the highly original paleo ecosystem of pseudobioherms

csees an expert system for analysis and design of cut slopes and embankments an expert system is developed for evaluating failure potential of cut slopes and embankments the fuzzy sets theory is used with the modified monte carlo simulation technique to obtain the slope failure potential index sfpi incorporating factors affecting slope stability such as geology topography geomorphology precipitation vegetation and drainage conditions the developed cut slopes and embankments expert system csees includes a classification system for evaluating failure potential of cut slopes and embankments and a data bank on landslides in jordan the proposed classification system and slope failure potential method proved to be successful for the areas that experienced landslides in the past the expert system can be used directly for areas with the same geological formations as those areas in which landslides occurred in the past and can be used for areas with other geological formations by modifying the rock type or foundation material type factor incorporated in the expert system

isotopic and geochemical investigation of two distinct mars analog environments using evolved gas techniques in svalbard norway the 2010 arctic mars analog svalbard expedition amase investigated two distinct geologic settings on svalbard using methodologies and techniques to be deployed on mars science laboratory msl amase related research comprises both analyses conducted during the expedition and further analyses of collected samples using laboratory facilities at a variety of institutions the sample analysis at mars sam instrument suite on msl includes pyrolysis ovens a gas processing manifold a quadrupole mass spectrometer qms several gas chromatography columns and a tunable laser spectrometer tls an integral part of sam development is the deployment of sam like instrumentation in the field during amase 2010 two parts of sam participated as stand alone instruments a hiden evolved gas analysis mass spectrometer ega qms system represented the ega qms component of sam and a picarro cavity ring down spectrometer ega crds represented the ega tls component of sam a field analog of chemin the xrd xrf on msl was also deployed as part of this field campaign carbon isotopic measurements of co2 evolved during thermal decomposition of carbonates were used together with ega qms geochemical data mineral composition information and contextual observations made during sample collection to distinguish carbonates formation associated with chemosynthetic activity at a fossil methane seep from abiotic processes forming carbonates associated with subglacial basaltic eruptions carbon and oxygen isotopes of the basalt hosted carbonates suggest cryogenic carbonate formation though more research is necessary to clarify the history of these rocks

bioerosion and carbonate mud production on high latitude shelves low latitude carbonate muds often are composed either of entire units of skeletons e g algal muds or of precipitates whereas high latitude carbonate muds are bioerosional or result from maceration bioerosion at high latitudes is most intense in the photic zone particularly down to 25 m depth shelly substrata may be crushed bitten drilled bored or scraped clionid sponges endolithic algae acmaeid gastropods and regular echinoids are the most significant agents clionids produce distinctive facetted carbonate silt chips when boring which have been described from both high and low latitudes faecal pellets break down to yield mud sized carbonate particles that are more irregular than those produced by maceration exhumed infaunal bivalves are often preferred to epifaunal organisms as substrata bioerosion occurs very rapidly shells may be totally infested with boring algae in three months a moth eaten appearance therefore does not denote a relict grain reliable rates of fine sediment production are not yet available the mud fraction of northwest european shelf sediment generally contains 10 20 caco3 though an inshore and offshore belt with higher values may be identified some holocene supratidal mud flats exceed 50 caco3 much of the shelf represents a modern day equivalent of the calcareous shale facies common in the geological record instances of synsedimentary cementation are not uncommon particularly in association with heavily burrowed muds

sensitivity of eurasian climate to surface uplift of the tibetan plateau experiments with climate models are used to illustrate how earth s climate could be expected to change if surface uplift occurred the experiments contrast two climate simulations one with all continents at sea level and one with present day mountains and plateaus the simulations in the eurasia sector show that surface uplift increased elevation produces marked increases in the intensity of summer and winter monsoons of asia with development of wetter climates to the south and east of the tibetan plateau and drier climates to the north and west of the plateau there is a general cooling in northern polar latitudes comparison of simulations from two different models shows that the magnitude of the simulated changes depends upon how the models calculate the land surface hydrology and the ocean temperature the simulated changes produced by surface uplift agree in a general way with many geologic indicators of late cenozoic climate change the results suggest that surface uplift of mountains and platea

an 80 year summer temperature history from the xiao dongkemadi ice core in the central tibetan plateau and its association with atmospheric circulation abstract the climate significance of oxygen isotopes from the central tibetan plateau ctp ice cores is a debated issue because of large scale atmospheric circulation a high resolution 18 o record was recovered from the xiao dongkemadi xd ice core which expanded the spatial coverage of 18 o data in this region annual average 18 o correlated significantly with nearby mjjas air temperatures suggesting the 18 o can be used as a proxy to reconstruct regional climate change the reconstructed temperature anomaly is related to the regional and global warming trends and the greater warming amplitude since 1970s is related to the elevation dependency of the warming signal the close relationship of the warming to variations in glacier mass balances and discharge reveal that recent warming has led to obvious glacier shrinkage and runoff increase correlation analysis suggests that monsoon and westerly moisture substantially influence the ctp ice core records along with an increase in their level of contribution to the xd core accumulation in recent decades and confirms a teleconnection of regional climate of the ctp ice cores with climate parameters in the indian and north atlantic oceans

the impact of a weak horizon on kinematics and internal deformation of a failure mass using discrete element method abstract weak horizons within slopes may induce and or accelerate failure of slopes in this study we focus on the effect of orientation location and dimension of a weak horizon on the mode and kinematics of downslope movement of a failure mass using discrete element method two kinds of cases with weak horizons were studied one unstable homogeneous slope with low shear strength c 50 kpa 0 57 and two stable homogeneous slopes with high shear strength c 60 kpa 0 57 or c 50 kpa 0 7 in the three sets of slope models there was a weak horizon with a finite thickness embedded within the slope in each set of slope models two different thicknesses and locations for the weak horizons were considered to systematically investigate the effect of these parameters on the mass movement in addition the dip of the weak horizon was changed where in some models it was parallel to the slope and in others it was dipping either steeper or gentler than the slope we analyzed both kinematics and internal deformation of the failure mass in all models and conclude that the presence and geometry i e thickness location and dip of a weak horizon changes the mode and kinematics of mass movement and governs the location of the failure surface

analysis and remedies of landslides of cut slopes due to the presence of weak cohesive layers within stronger formations several cases of instability of cut slopes along major highways in jordan were reviewed in this study in some detail emphasis was placed on the amman irbid highway but some cases along the na ur dead sea highway were also reviewed with the aim of establishing a wider database of case studies and examining all possible mechanisms and factors influencing stability the study showed that major cut slope failures were caused by the presence of weak cohesive layers mainly clayey marl interbedded within mostly stronger formations in addition to the steep cutting angles and unfavorable dip of strata combined with relatively high piezometric surface brought about by poor surface and subsurface drainage no remedies were implemented to stabilize major cut slope failures at km 39 200 44 300 and 56 400 along the irbid jerash amman highway the three major cut slope failures require extensive remedial work and probably advanced geotechnology which is expected to be expensive to investigate the influence of various parameters on slope stability several analyses were performed in addition to back analyses to determine shear strength parameters parametric sensitivity studies were also performed on some cases data was obtained from previous investigations by local and international firms and were screened and modified where needed before being used in stability analyses considerable difference between back analysis and test result values for shear strength parameters were observed in many cases failure surfaces and mechanisms were accurately depicted in most cases allowing back analyses to be performed with considerable confidence the effective residual shear strength parameters for clayey marl needed for stability analysis were found to be c r 5 18 kpa and r 13 18 the relation between total annual rainfall and occurrence of landslides was investigated it was shown that all landslides occurred in years of very high rainfall with values always exceeding 400 mm the probability of exceeding the average total annual rainfall was found to be approximately 0 42 for the three gauging stations considered

mixing zone origin of 13c depleted calcite cement oseberg formation sandstones middle jurassic veslefrikk field norway abstract carbonate cement is one of the more volumetrically important diagenetic components of sandstones the sandstones of the fan delta facies of the oseberg formation brent group in veslefrikk field contain abundant carbonate cemented zones commonly comprised of 30 40 carbonate by volume the cement is predominantly poikilotopic ferroan calcite with minor amounts of ankerite and siderite petrographie evidence for high porosities at the time of calcite precipitation indicate that cementation occurred under shallow burial conditions probably less than 500 m crosscutting textural relations demonstrate that calcite cementation was predated and postdated by tectonic stresses that produced both grain fractures and through going fractures respectively in the non calcite cemented parts of the formation major compaction pressure solution feldspar dissolution and cementation by quartz and clays postdated calcite cementation the oxygen isotopic composition of the calcite averages 8 5 0 pdb and shows large variations within individual calcite cemented zones up to 10 0 in 18 o the depleted and variable oxygen isotopic composition in conjunction with evidence for shallow precipitation indicate calcite growth occurred in a mixing zone environment variably influenced by meteoric water isotopic variation within many individual cemented zones is symmetric about the center of the zones indicating that growth of the cemented zones was from the center outwards in a concretionary fashion the high fe and mn content of the calcite avg 1 3 mol fe avg 0 4 mol mn and its association with disseminated pyrite indicate that porewater was reducing during precipitation carbon isotopic data avg 13 c 15 7 0 pdb range 3 to 3 1 0 show that major amounts of organic carbon at least partly derived by sulfate reduction of biogenic methane were incorporated in the calcite other documented occurrences of early 13 c depleted carbonate cemented sandstones are similar to the carbonate cement in veslefrikk field in their association with methane oxidation and their low temperature formation however the cement at veslefrikk differs in its mineralogical and morphological occurrence and in the fact that it formed from a porewater strongly influenced by mixing with meteoric water key geologic factors that determined the traits of calcite cement in veslefrikk field are the combination of nearshore marine deposition of permeable sands close proximity of organic rich marine muds and variations in relative sea level which provided opportunities for invasion by meteoric water these geologic factors had a similar impact on other brent group deltaic sandstones and are believed to explain some of the differences between the geochemistry of carbonate cements in deltaic and shelf sandstones of the north sea and elsewhere

chemistry and mineralogy of pyrite enriched sediments at a passive margin sulfide brine seep abyssal gulf of mexico pyrite is rapidly accumulating at the contact between the cretaceous limestones of the florida platform and the hemipelagic sediments of the abyssal gulf of mexico sediments sampled with the submersible alvin in 3266 m of water are associated with a dense community of organisms that depend on chemosynthetic primary production as a food source analysis of the chemistry mineralogy and textural composition of these sediments indicate that iron sulfide mineralization is occurring at the seafloor within an anoxic micro habitat sustained by the advection of hydrogen sulfide charged saline brines from the adjacent platform the chemosynthetic bacteria that directly overlie the sediments oxidize hydrogen sulfide for energy and provide elemental sulfur that reacts with iron monosulfide to form some of the pyrite the sediments are mixtures of pyrite 30 wt basr sulfates 4 wt clays and locally derived biogenic carbonates and are progressively being cemented by iron sulfides oxidation of hydrogen sulfide produces locally acidic conditions that corrode the adjacent limestones potential sources of s h2s fe ba and sr are discussed

palaeoecology and evolution of marine hard substrate communities abstract marine organisms have occupied hard substrates since the archaean shells rocks wood and sedimentary hardgrounds offer relatively stable habitats compared to unconsolidated sediments but the plants and animals which inhabit them must develop means to gain and defend this premium attachment space hard substrate communities are formed by organisms with a variety of strategies for adhering to and or excavating the substrates they inhabit while mobile grazers organically attached and even soft bodied organisms may leave evidence of their former presence in ancient hard substrate communities a superior fossil record is left by sessile encrusters with mineralised skeletons and by borers which leave trace fossils furthermore encrusters and borers are preserved in situ retaining their spatial relationships to one another and to the substrate spatial competition ecological succession oriented growth and differential utilisation of exposed vs hidden substrate surfaces can all be observed or inferred hard substrate communities are thus excellent systems with which to study community evolution over hundreds of millions of years here we review the research on modern and ancient hard substrate communities and point to some changes that have affected them over geological time scales such changes include a general increase in bioerosion of hard substrates particularly carbonate surfaces through the phanerozoic this is at least in part analogous to the infaunalisation trends seen in soft substrate communities encrusting forms show an increase in skeletalisation from the palaeozoic into the mesozoic and cenozoic which may be a response to increasing levels of predation hard substrate communities considering borers and encrusters together show a rough increase in tiering through the phanerozoic which again parallels trends seen in soft substrate communities this extensive review of the literature on living and fossil hard substrate organisms shows that many opportunities remain for large scale studies of trends through time at the community and clade levels palaeontologists will especially benefit by closer integration of their work with that of neontologists particularly in aspects of ecology such as larval recruitment competition and succession

continental margin brine seeps their geological consequences local dissolution observed at the base of the florida escarpment appears to result from acid generated by sea floor oxidation of dissolved sulfide species carried in brines that seep from the base of the escarpment the extent of seep corrosion depends upon the amount of sulfide that has exited the platform and the efficiency with which the acid attacks the limestones of the escarpment calculations suggest that brine seepage influences the shape of these escarpments by undercutting and steepening the carbonate continental margin edges other processes competing for the dissolved sulfides are bacterial chemosynthesis and sulfide mineralization which produces organic carbon and sulfide mineral rich deposits along the unconformity that separates the buried escarpment from onlapping abyssal sediments

description and ecology of recent endolithic biota from the gulf islands and banks in the strait of juan de fuca british columbia eleven endolithic forms were distinguished from skeletal fragments collected near the gulf islands and from banks in the strait of juan de fuca british columbia the vast majority of studies dealing with endoliths are from tropical regions however the abundance of boring organisms described herein demonstrates their importance as sedimentological agents in mid latitudes as well although some if not most of the borings occurred after the substrate organism was dead the order of infestation was indeterminant fungal borings are densely distributed when in close proximity to algae although the nature of this biological association remains undefined this relationship suggests that fungi prefer utilizing algae as an energy source the observed decreased infestation of algal endoliths in shallow environs less than 30 m compared with that in deeper water might be attributed to less exposure in a high energy regime or to a freshness factor of the shells algal endoliths were observed in several shell substrates obtained from below the photic zone defined as 45 m on the basis of the deepest occurrence of encrusting red algae this distribution of endolithic microphytes indicates that any bathymetric zonation that may have been initially present was disturbed by the lateral transport of substrate particles furthermore this suggests that algal borings should not be used independently of other environmental information to determine paleobathymetry

early carboniferous low temperature hydrothermal vent communities from newfoundland living vent communities dependent on microbial chemosynthesis rather than photosynthesis were discovered only in the 1970s1 since then six fossil vent communities have been identified they range in age from early carboniferous to early tertiary2 7 here we describe fossil tubes an abundant low diversity fauna and sulphide mineralization in 340 myr old carboniferous carbonate mounds in newfoundland fig 1a these features together with evidence for microbial activity point to the existence of a seventh chemosynthetic community clustered around low temperature hydrothermal vents the remarkable preservation of this newfoundland community allows a direct comparison to be made with the composition and structure of modern vent communities

an early jurassic deep water stromatolitic bioherm related to possible methane seepage los molles formation neuquen argentina an assemblage of microbial stromatolites and worm tubes makes up a limestone bioherm 15 m thick and 60 m in diameter enclosed in marls and dark shales of the early jurassic los molles formation neuquen basin argentina the los molles formation is a basinal unit consisting primarily of shales silts and sandstone turbidites deposited after the first general marine transgression in the basin below storm wave base in relatively deep water poorly oxygenated conditions the bioherm is composed of stacked stromatolites 1 4 m in diameter and 1 2 m thick they initially grew horizontally tabular stromatolites or vertically columnar stromatolites and later became domal equidimensional to asymmetric structures they often display vertical and overturned flanks each stromatolite consists of micritic laminae alternating with early botryoidal cements which make up the bulk of the structure calcareous worm tubes are embedded in peloidal micrite associated with the stromatolites the growth of the assemblage was uninterrupted by terrigenous input the diagenetic sequence indicates evolution from marine phreatic to burial environments isotopic values for micrite worm tubes early botryoidal cements and spar cements yield very negative 13c values down to 33 and negative 16o values down to 11 these depleted values indicate precipitation in very anomalous conditions in the jurassic ocean under the influence of methane rich fluids these characteristics suggest that the stromatolitic bioherm formed in relation to methane seeps in the seafloor of the neuquen basin it is suggested that the structure grew within the photic zone although a chemosynthetic component cannot be excluded minimum depositional depth has been estimated at 50 m and could be up to 100 m the vent fluids would have migrated through shallowly buried early rift faults which bound underlying depocenters infilled with continental clastic and volcanic rocks the origin of these fluids could be related to magmatic activity which resulted in accumulation of the syn rift volcanics alternatively the structure could indicate seepage related to the presence of hydrocarbon accumulations in the syn rift succession during the jurassic the importance of which is being gradually acknowledged in the petroleum system of the neuquen basin

mechanism of reactivated badu landslide in the badu mountain area southwest china this paper presented the reactivated mechanism of badu landslide according to site investigations monitoring finite element and limit equilibrium analyses finite element analysis incorporating a stability analysis with the finite element stress based method revealed a large railway cut triggered a localized slide in the upper part of badu landslide rather than a global failure and piles in three rows were effective in stabilizing the reactivated zone monitoring results and the limit equilibrium analysis showed that the landslide underwent multi instabilities rather than a global failure due to a rise in groundwater table in rainy season the mechanism of reactivated badu landslide was finally proposed i e grading creeping sliding mechanism which helped designers to propose the most suitable mitigation measures to stabilize the landslide

saretl an expert system for probabilistic displacement based dynamic 3 d slope stability analysis and remediation of earthquake triggered landslides different models were developed for evaluating the probabilistic three dimensional 3 d stability analysis of earth slopes and embankments under earthquake loading using both the safety factor and the displacement criteria of slope failure in the 3 d analysis the critical and total slope widths become two new and important parameters the probabilistic models evaluate the probability of failure under seismic loading and consider the different sources of uncertainties involved in the problem i e uncertainties stemming from the discrepancies between laboratory measured and in situ values of shear strength parameters randomness of earthquake occurrence and earthquake induced acceleration the models also take into consideration the spatial variabilities and correlations of soil properties the developed models are incorporated in a computer program ptddssa probabilistic three dimensional dynamic slope stability analysis these developed analysis design procedures are incorporated within a code named saretl stability analysis and remediation of earthquake triggered landslides that was developed in this study for stability analysis and remediation of earthquake triggered landslides in addition to the dynamic inertia forces the developed system takes into consideration the local site effects the code is capable of 1 prediction of permanent deformations that result from landslides under seismic loading using both probabilistic and deterministic approaches 2 the assessment of landslide hazard that affects major transportation routes in the event of earthquakes and the preparation of earthquake induced landslide hazard maps i e maps that show expected displacements and probability of slope embankments failure for different earthquakes magnitudes and environmental conditions 3 proposing a mitigation strategy against landslides and suggesting guidelines for remedial measures the developed expert system is applied to a major highway case study design maps are developed for the highway under seismic loading

an ordovician lost city venting serpentinite and life oases on iapetus seafloor highly brecciated carbonate rich serpentinites or ophicalcites of early ordovician age in the dunnage zone of quebec are host to fracture fill high temperature 80 230 c carbonate cements away from or crosscut by the fractures centimetre to decimetre thick crusts made up of massive to laminated micrite peloidal layers and threads are associated with low temperature botryoidal calcite cements the peloidal masses are characterized by a clotted texture that is reminiscent of interpreted fossilized ordovician microbial communities the ophicalcite contains carbonate botryoids morphology commonly found at shallow reefal margins but also at modern cold ch4 seeps and recently documented at hot ch4 vents from serpentinite such as the modern lost city hydrothermal field in the atlantic ocean the 18ovpdb ratios of the calcite botryoids and peloidal layers indicate formation and or precipitation out of cold ordovician deep marine waters to the contrary of botryoids at cold methane seeps the botryo

biodegradation of temperate water skeletal carbonates by boring sponges on the scott shelf british columbia canada abstract boring sponges are a major agent of shell destruction and in the process an important contributor of fine grained carbonate detritus in temperate skeletal carbonate deposits on scott shelf northwestern vancouver island intensive boring is encouraged by the generally low rates of carbonate production and sedimentation skeletal grains become considerably weakened by sponge boring and break preferentially along the directions of sponge excavated tunnels and galleries within the shell boring also facilitates shell dissolution by significantly increasing the surface area weight ratio of shells and by breaking down the organic matrix of shells the large aragonitic bivalves glycymeris and humilaria appear especially susceptible to sponge biodegradation and have become thoroughly bored and corroded within about 1000 years in ambient shelf waters thus their preservation potential is low selective loss of aragonitic biota from ancient cool water shelf skeletal carbonate deposits is anticipated and is evident in many temperate latitude occurrences of new zealand cenozoic limestones

methane derived high mg calcite submarine cement in holocene nodules from the fraser delta british columbia canada carbonate nodules and slabs in late holocene shelly terrigenous deposits of the modern fraser river delta 49 n are formed close to the seafloor by precipitation from saline pore waters of mainly fibrous to bladed crystals of high mg 10 20 mol mgco3 calcite cement as coalescing isopachous crusts on grains previous reports that the cement is low mg calcite are not supported by this study highly negative 13c values of 7 to 59 for the cements indicate that the bulk of their carbonate carbon was derived from the microbiological degradation of organic matter in the deltaic deposits during shallow burial in particular the production of biogenic methane ch4 by anaerobic bacterial fermentation its upward migration chemical or biological oxidation to co2 and neutralization in the near surface sediment and diffusion to microenvironments relatively enriched in organic components are a possible set of conditions influencing the process and sites of carbonate cementation methane derived mg calcite appears also to be the major submarine cement in several other modern occurrences of lithified shallow water terrigenous sands and muds at non tropical latitudes

sea level changes versus hydrothermal diagenesis origin of triassic carbonate platform cycles in the dolomites italy abstract the triassic platform carbonate cycles of the dolomites best developed and studied at the latemar have been considered key examples for the documentation of eustatic sea level changes the cycles appear to reflect a low energy lagoonal environment which is however difficult to reconcile with the small platforms lacking marginal energy barriers in a tropical stormy climate an alternative interpretation to eustatically controlled cyclicity and repeated subaerial exposure is provided by diagenesis in a hydrothermal field elevated heat flow 0 2 ma before the onset of the mafic igneous activity triggered the circulation of diagenetic fluids with a composition similar to seawater by intermittent opening of fractures through some platforms this caused tepee formation by precipitation of displacive cement pendant cement and pisolite formation and favoured cyanobacterial mat formation and their early dolomitization the abundance of cycles correlates with that of the somewhat younger volcanic dikes crosscutting some platforms diffuse venting or seeping in the upper unconsolidated sediment layers explains the stratiform occurrence of the diagenetic features and alternation with normal marine deposition in deep but photic water at the wave base

stable carbon isotope records of carbonates tracing fossil seep activity off indonesia stable isotope records of carbonates from up to 20 m long sediment cores from the forearc basin of the sunda arc display significant 13c depletion deviating from expected normal marine levels by 5 to 40 peedee belemnite pdb this depletion is interpreted to be caused by methane seepage and associated authigenic carbonate precipitation in sediments near the seafloor about 2 m sized globular carbonate particles found in isotopically depleted samples support this interpretation their shape suggests microbial mediation of the precipitation process investigation of benthic foraminiferal assemblages in cores which record seep influence indicate times of high abundance with an up to twentyfold increase of the population and a dominance of opportunistic infaunal taxa we relate these events to the seepage of methane thus providing an understanding of the duration and age of this postdepositional process postulated seep activity is most intense between 3 7 kyr b p and 27 33 kyr b p as cores with 13c isotope depletion were taken atop active fault zones in the forearc we suggest a tectonic control of the seepage records of seep activity thus may have the potential to archive imprints of tectonic activity

a 47 year high resolution chemistry record of atmospheric environment change from the laohugou glacier no 12 north slope of qilian mountains china abstract based on a 20 12 m shallow ice core drilled at the laohugou glacier no 12 39 25 7 n 96 33 4 e 5040 m a s l north slope of qilian mountains in the northeastern qinghai tibetan plateau in june 2006 the changes of atmospheric environment over the qilian mountains and northwestern china recorded by ice chemistry and its possible connection with atmospheric circulation and the winter north atlantic oscillation nao are investigated a total of 606 samples were analyzed for major ions ca2 na k mg2 nh 4 cl so 4 2 and no 3 and stable oxygen isotope ratios 18o the ion chemistry of the ice core covering the past 47 years is mainly characterized by mineral dust species ca2 na mg2 so 4 2 cl and k and anthropogenic species so 4 2 nh 4 and no 3 ca2 is the dominant cation in the ice core with a medium value of 2815 5 eq l 1 accounting for 65 8 of the total cations and so 4 2 is the predominant anion with a medium value of 1500 4 eq l 1 accounting for 45 8 of the total anions compared with ice core records from altai and himalayas at the northern and southern margin of western china respectively dust related species concentrations in the laohugou ice core are much higher due to pronounced regional crustal dust aerosol inputs from surrounding arid and semiarid deserts the results show that dust species concentrations decreased during 1960 2006 a d while non dust species so 4 2 nh 4 and no 3 anthropogenic species concentrations increased which indicating that the ice core record of dust storm activity over qilian mountains exhibits a significant decreasing trend during the past 47 years this change of dust species may be caused by decrease in wind speed and increase in precipitation over the laohugou surrounding areas in qilian mountains and northwestern china and wind speed decrease is probably caused by spatial differences of inter decadal air temperature change of the 600 hpa in central asia the normalized time series of the winter nao index shows a significant inverse correlation with the annual flux of ca2 in dust implying a possible connection between the winter nao and the dust storm activity over the qilian mountains

benthic carbonate factories of the phanerozoic marine carbonate precipitation occurs in three basic modes abiotic or quasi abiotic biotically induced and biotically controlled on a geologic scale these precipitation modes combine to form three carbonate production systems or factories in the benthic environment 1 tropical shallow water factory dominated by biotically controlled mainly photo autotrophic and abiotic precipitates 2 cool water factory dominated by biotically controlled mainly heterotrophic precipitates and 3 mud mound factory dominated by biotically induced mainly microbial and abiotic precipitates sediment accumulations of the factories differ in composition geometry and facies patterns and some of these differences appear prominently in seismic data thus facilitating subsurface prediction the characteristic accumulation of the tropical factory is the flat topped often reef rimmed platform in cool water systems reefs in high energy settings are scarce and hydrodynamic influence dominates producing seaward sloping shelves and deep water sediment drifts often armored by skeletal framework the typical accumulation of the mud mound factory is groups of mounds in deeper water where the mud mound factory expands into shallow water it forms rimmed platforms similar to the tropical factory the tropical factory is most productive the mud mound factory reaches 80 90 and the cool water factory 20 30 of the tropical growth rate the three factories represent end members connected by transitions in space transitions in time are linked to biotic evolution

high resolution atmospheric cadmium record for ad 1776 2004 in a high altitude ice core from the eastern tien shan central asia two ice cores drilled to the bottom were recovered from miaoergou flat topped glacier 43 03 19 n 94 19 21 e 4512 ma s l eastern tien shan central asia in 2005 a high resolution record of cadmium was established by applying inductively coupled plasma mass spectrometry to one of the ice cores 57 6 m covering a 228 year period from ad 1776 to 2004 the results showed long term variations of atmospheric transport and deposition of cadmium at high altitudes trend analysis based on the sequential mann kendall test and the analysis of crustal enrichment factors of the cadmium shows that natural contribution mainly from rock and mineral dust dominated the atmospheric cycles of cadmium during the period ad 1776 1957 which was confirmed by the significant correlation between the winter north atlantic oscillation nao index and annual cadmium concentration the concentration of cadmium increased sharply from ad 1957 to 2004 suggesting increasing influence from human activities such as metals production the ice core record indicated increasing atmospheric cadmium pollution in response to rapid economic growth after ad 1957 in the region

investigation of failure of highway embankment founded on colluvium and suggested stabilization measures for reconstruction abstract the landslide at km 38 600 along the irbid amman highway in jordan was the result of foundation instability during the exceptionally heavy rainfall season of 1991 1992 the area of the landslide is approximately 42 000 m 2 carrying an estimated volume of 500 000 m 3 this paper summarized the detailed geotechnical investigation carried out at the site to identify the causes and mechanism of failure and recommends remedial measures the slope failure resulted from two major causes the presence of lateral failure planes within the colluvium aligned in a direction that promotes failure and the lack of adequate drainage within the colluvium material the following remedial alternatives are recommended the material existing in the base of the embankment should be excavated and replaced with properly compacted material incorporating a suitable drainage system and the road should be realigned with the slopes founded on rock and cut at a safe angle

variations in annual accumulation recorded in a laohugou ice core from the northeastern tibetan plateau and their relationship with atmospheric circulation annual accumulation was reconstructed for a period from 1960 to 2006 using a 21 2 m ice core from the firn basin of laohugou lhg glacier no 12 on the northeastern tibetan plateau tp significant periodicity of lhg accumulation variations was identified as a quasi 3 year period in accordance with the oscillation of precipitation in the northwestern china especially the hexi corridor furthermore the relationships of lhg accumulation with atmospheric circulation and moisture sources were investigated lhg accumulation was positively correlated with the 500 hpa geopotential height and pressure in central asia as well as the autumn northern atlantic oscillation suggesting that the westerlies may transport moisture to the lhg region and enhance precipitation in addition a negative relationship between lhg accumulation and meridional wind indicated that an intense mongolian cyclone caused by a strong meridional wind in the region could block arctic air masses from the lhg region moisture fluxes and backward air mass trajectories suggested that moisture might originate from central asia southern and the inland tp the relationship between lhg accumulation and atmospheric circulation provides an opportunity to reconstruct the history of atmospheric circulation using a deep ice core record

cretaceous cold seep communities and methane derived carbonates in the canadian arctic lower cretaceous cold seep fossil assemblages have been found in the canadian arctic archipelago serpulid worm tubes and bivalves are most abundant in these communities in contrast fossils are scarce in the surrounding strata the fossils are contained in an isotopically light delta 13 c 25 to 50 per mil carbonate rock groundmass that is interpreted to have formed from bacterial oxidation of methane the rocks were deposited at intermediate depth 400 meters in a cold marine environment nearby normal faults may have provided a conduit for seeping methane and hydrogen sulfide needed to fuel chemosynthetic bacteria and in turn the higher life forms

tibetan plateau summer monsoon northward extent revealed by measurements of water stable isotopes a program of individual precipitation events and river water sampling and of water isotopic measurements d 18o was carried out during summer 1996 along a northeast southwest transect of the tibetan plateau the spatial distribution of both 18o and deuterium excess d d 8 18o of the precipitation reveals three distinct regions simulations with a simple isotopic model and seasonal isotopic variations measured at two extreme south and north locations support our interpretation in terms of different summer moisture origins 1 south of the himalayan mountains the moisture provided by the indian monsoon has been recycled over the indian peninsula 2 between the himalayas and the tanggula mountains the oceanic moisture is directly transported from the bay of bengal along the brahmaptra river valley 3 north of the tanggula mountains the moisture is not provided by the monsoon anymore but by continental water recycling

iron ore of the lahn dill type formed by diagenetic seeping of pyroclastic sequences a case study on the schalstein section at gansberg weilburg investigations on the reconstruction of processes and facies relationships from submarine volcanics of devonian age in the lahn syncline rhenish mountains western germany reveal a complex development of secondary alteration this is well illustrated by a mafic pyroclastic sequence schalstein at the gansberg near weilburg where alteration processes are visible by petrographic and geochemical means and can be further classified by cathodoluminescence iron ore formation of lahn dill type is recognized as part of this alteration process resulting from diagenetic seeping until recently a direct magmatic source for the lahn dill type iron ore has been the generally accepted model these bodies have therefore been viewed as a rather unique stratiform deposit whose occurrence was virtually confined to this type area however it is here considered that the formation of the iron ore corresponds well with existing models of alteration processes within recent oceanic environments which are of a more universal occurrence

a fossil hydrothermal worm assemblage from the tynagh lead zinc deposit in ireland fossil hydrothermal chimneys were first discovered at silvermines1 ireland subsequent discoveries of fossils associated with mounds and chimneys in sulphide deposits within the ophiolite complexes of cyprus2 and oman3 prove that life forms similar to those colonising active vents on the east pacific rise4 7 were extant 100 myr ago around ridge crest hot springs here i report the discovery of 350 myr old worm like fossils recovered from pyrite chimneys associated with sedimentary exhalative mineralization at tynagh ireland this find suggests that even older examples of life existing at seafloor hot springs may be awaiting discovery

a 1000 year history of atmospheric sulfate concentrations in southern asia as recorded by a himalayan ice core 1 a sulfate record covering the period a d 1000 1997 from the dasuopu glacier in the himalayas reveals that this site is sensitive to anthropogenic activity originating in southern asia prior to 1870 atmospheric sulfate concentrations were relatively low and constant but thereafter concentrations have increased and since 1930 the rate of increase has accelerated rapidly this accelerating trend in sulfate deposition is paralleled by growing so2 emissions over southern asia resulting from the increased energy demand the concentration of sulfate deposited in the last 50 years exceeds that for any prior 50 year period in the last millennium unlike the greenland ice core derived sulfate concentrations that have declined since the 1970s sulfate concentrations deposited on the himalayan ice fields continue to increase having nearly doubled since 1970 this reflects regional differences between europe and asia in source strength and transport pathways for atmospheric sulfate as well as differing degrees of environmental regulation