late quaternary palaeoenvironment of northern guatemala evidence from deep drill cores and seismic stratigraphy of lake peten itza long sediment cores were collected in spring 2006 from lake peten itza northern guatemala in water depths ranging from 30 to 150 m as part of an international continental scientific drilling program project the sediment records from deep water consist mainly of alternating clay gypsum and carbonate units and in at least two drill sites extend back 200 kyr most of the lithostratigraphic units are traceable throughout the basin along seismic reflections that serve as seismic stratigraphic boundaries and suggest that the lithostratigraphy can be used to infer regional palaeoenvironmental changes a revised seismic stratigraphy was established on the basis of integrated lithological and seismic reflection data from the basin from ca 200 to ca 85 ka sediments are dominated by carbonate clay silt often interbedded with sandy turbidites indicating a sediment regime dominated by detrital sedimentation in a relatively humid climate at ca 85 ka an exposure horizon consisting of gravels coarse sand and terrestrial gastropods marks a lake lowstand or partial basin desiccation indicating dry climate conditions from ca 85 to ca 48 ka transgressive carbonate clay sediments overlain by deep water clays suggest a lake level rise and subsequent stabilization at high stage from ca 48 ka to present the lithology is characterized by alternating clay and gypsum units gypsum deposition correlates with heinrich events i e dry climate whereas clay units coincide with more humid interstadials

hydrogen and carbon abundances and isotopic ratios in apatite from alkaline intrusive complexes with a focus on carbonatites we report h and c contents and d and 13 c values of apatites from 15 alkaline intrusive complexes ranging in age from 110 ma to 2 6 ga sampling focused on carbonatites but included silicate rocks as well heating at temperatures up to 1500 c is needed to extract fully h 2o and co 2 from these apatites apatites from carbonatite rich intrusive complexes contain 0 2 1 1 wt h 2o and 0 05 0 70 wt co 2 apatites from two silicate rich alkaline complexes with little or no carbonatite are generally poorer in both volatile components 0 1 0 2 h 2o and 0 01 0 11 co 2 d h ratios in apatites from these rocks are bimodally distributed group i d 51 to 74 and group ii d 88 to 104 we suggest that the d values of group i apatites represent primitive mantle derived values and that the group ii apatites crystallized from degassed magmas resulting in lower h 2o contents and d values although many factors influence the extent of degassing the depth of emplacement could represent a major control in contrast to h 2o contents and d values co 2 contents and 13 c values of gas released at high temperatures from multiple aliquots of these apatite samples are variable this suggests the presence of more than one c bearing component in these apatites one of which is proposed to be dissolved carbonate the other with 13 c 25 could be associated with hydrocarbons group i apatites have d values similar to those of primitive mantle derived basaltic magmas and overlap with but cover a narrower range than mantle derived mica amphibole and whole rocks 13 c values also overlap typical upper mantle these results suggest that igneous apatites can retain their primary d and 13 c values

apatite as a monitor of late stage magmatic processes at volcan irazu costa rica apatite phenocrysts from the 1963 and 1723 eruptions of irazu volcano costa rica record a volatile evolution history that confirms previous melt inclusion studies and provides additional information concerning the relative and absolute timing of subvolcanic magmatic events measurements of h cl and f by secondary ion mass spectrometry reveal multiple populations of apatite in both 1723 and 1963 magmas assuming nominal apatite melt partition coefficients allows us to compare the pattern of melt inclusions and apatites in ternary space demonstrating the fidelity of the record preserved in apatite and revealing a complex history of magma mixing with at least two components the preservation of heterogeneous populations of apatite and of internally heterogeneous crystals requires short timescales days to years for these magmatic processes to occur

reconstructing recent environmental changes from proglacial lake sediments in the western alps lake blanc huez 2543 m a s l grandes rousses massif france abstract the evolution of high altitude glaciers and human activities in the grandes rousses massif is documented by high resolution seismic reflection profiling and multiproxy analysis of short sediment cores in proglacial lake blanc huez these lacustrine data are compared with historical chronicles geomorphological features and glaciological studies in this region of the western alps and they allow the documentation of recent environmental changes the specific geometry of high amplitude reflections in the uppermost seismic unit the lithology of short cores and the available limnological data in the lake suggest that clastic particles eroded by the glaciers and transported in suspension by glacial melt waters in early summer essentially develop homopycnal flood events in the lake a conceptual model linking fluctuations of glacier equilibrium line altitudes in the catchment area with sedimentary facies retrieved in the lake basin is proposed this approach allows reconstructing continuous glacier fluctuations since ad1820 1850 and suggests several phases of glacier fluctuations during the little ice age lia these reconstructions are based on changes in lacustrine sediment laminations density magnetic susceptibility reflectance spectra organic matter and arsenic content the age depth model of short sediment cores is provided by 210 pb 137 cs and 241 am radionuclide dating this chronology is further supported by identifying in lacustrine sediments the impact of i the nearby m 5 3 correncon earthquake in ad 1962 ii the development of the ski resort at high altitude close to the lake and iii the last advance of glaciers during the lia in ad1820 1850 and the following phase of glacier retreat observed in the alpine region at the end of the lia in ad 1880 frequent sandy layers enriched in organic matter and associated with fluctuations in the arsenic concentrations may result from hydraulic remobilisation of middle age mine tailings at the lake shore by snow melt or heavy rain fall events during the lia

halogen chemistry and hydrogen isotopes of apatite from the 3 7 ga isua supracrustal belt sw greenland abstract the origin and evolution of volatiles particularly water in the abiotic early earth environment have been intensively studied and this is a topic of high relevance when considering the timing and conditions of life s emergence investigation of hydrogen isotopes in the oldest crystals of minerals from the apatite group ca10 po4 6 f cl oh 2 should bring new insight to this topic as the d h ratio of apatite has proved useful for establishing the evolution of volatiles in other solar system bodies apatite crystals from metasedimentary and metavolcanic rocks collected from a low strain domain of the eoarchean isua supracrustal belt have been investigated for their d h signatures using secondary ion mass spectrometry and for major and trace element abundances using epma and laser ablation icp ms apatite crystals from isua have a broad range in volatile compositions both within samples from the same lithology e g banded iron formation bif and between different lithologies bif metacarbonate mafic dyke most of the crystals are chlorine rich which is in contrast to typical modern sedimentary apatite that is predominantly carbonate fluorapatite we have used the ree distribution patterns from isua apatite to distinguish those crystals having sedimentary metasomatic and magmatic origins the d h ratios for all samples were determined to be very low with dvsmow values falling within the range from 93 to 56 d values of isua apatite do not correlate with ree signatures of crystals nor could we relate d to the host lithologies we conclude that this geochemical system has been reset during long and multi phase geologic history making it difficult if not impossible to use hydrogen isotopes for assessment of the primary signatures of the archean hydrosphere

lunar apatite with terrestrial volatile abundances the moon is thought to be depleted relative to the earth in volatile elements such as h cl and the alkalis nevertheless evidence for lunar explosive volcanism has been used to infer that some lunar magmas exsolved a co rich and co 2 rich vapour phase before or during eruption although there is also evidence for other volatile species on glass spherules until recently there had been no unambiguous reports of indigenous h in lunar rocks here we report quantitative ion microprobe measurements of late stage apatite from lunar basalt 14053 that document concentrations of h cl and s that are indistinguishable from apatites in common terrestrial igneous rocks these volatile contents could reflect post magmatic metamorphic volatile addition or growth from a late stage interstitial sulphide saturated melt that contained 1 600 parts per million h 2o and 3 500 parts per million cl both metamorphic and igneous models of apatite formation suggest a volatile inventory for at least some lunar materials that is similar to comparable terrestrial materials one possible implication is that portions of the lunar mantle or crust are more volatile rich than previously thought

volatiles in the martian crust and mantle clues from the nwa 6162 shergottite abstract martian meteorites of various petrogeneses retain a record of volatiles on mars from the hydrosphere crustal water to the mantle sputtering of the martian atmosphere by solar wind after the loss of mars magnetic field enriched it in deuterium which exchanged with martian crustal water recent studies show that the hydrogen isotopic composition of the martian crustal water reservoir varies from 3000 to 7000 but requires better constraints melt inclusion glasses maskelynite and fusion crust from the depleted olivine phyric shergotite nwa 6162 were analyzed using nanosims providing a unique insight into the hydrogen isotopic and volatile elemental content of both the martian crustal water reservoir and the mantle source the h2o s and cl contents of the melt inclusion glasses are 0 3137 14 239 and 16 967 ppm respectively d values vary from 560 to 6137 the water content positively correlates with the d values in both the melt inclusion glasses and maskelynite in a two end member mixing trend one end member is the magmatic water with a d value of 0 and the other end member is the martian crustal water with d ranging from 5000 to 6000 nwa 6162 a depleted olivine phyric shergottite originated from a different mantle source to the enriched lherzolitic shergottites however both types of shergottites exchanged with martian crustal water with the same d values indicating a homogeneous martian crustal water hydrogen isotopic composition 5000 6000 most melt inclusion glasses from nwa 6162 have low water content 0 234 ppm except for two enriched locations as micron sized bands and dendrites the low water content in most melt inclusion glasses the dendritic shaped water enriched areas in melt inclusions and the martian crustal water diffusion profile recorded in maskelynite collectively suggest short lived water rock interactions in the nwa 6162 parent rock that was probably induced by impact furthermore a great contribution up to 98 of surface cl accompanying d enriched water was recorded in the melt inclusions supported by the positive correlation between cl and h2o the presence of sulfide and s rich hot spots and low d end member of the magmatic water indicate that the degassing during post entrapment crystallization and ascent of the melt inclusion is negligible h2o s and cl contents of the martian mantle reservoir are estimated to be 0 1 3 0 5 15 and 0 5 4 ppm respectively after the correction of fractional crystallization of the melt inclusions and contribution from the martian surface reservoir the martian mantle reservoir estimated from nwa 6162 was water s and cl poorer than the earth s interior

carbon concentrations and isotopic ratios in fluid inclusion bearing upper mantle xenoliths along the northwestern margin of north america abstract at least three and perhaps four carbon components have been identified by step heating extraction of upper mantle xenoliths from nunivak island and prindle volcano alaska fort selkirk and alligator lake yukon jacques lake and castle rock british columbia one component released mostly between 200 and 600 c comprises 30 95 of the total carbon extracted and has 13c values between 28 and 23 this carbon corresponds mostly to complex carbon compounds condensed on surface minerals and cracks and will be referred to as isotopically light carbon ilc co2 released between 600 and 800 c is derived from interstitial carbonates it has variable 13c and concentrations that generally do not exeed 24 ppm c the carbon extracted from 1000 to 1450 c is a mixture of co2 from fluid inclusions and the ilc fraction the amount of ilc released in this temperature interval never exceeds 10 ppm because part of this ilc may have been introduced from the host lava the 13c variations of this carbon extracted above 800 c is not only characteristic for the original carbon present in fluid inclusion poor xenoliths however xenoliths enriched in co2 fluid inclusions show c isotopic variations at the highest temperature steps that fall in a relatively narrow range between 10 and 4 depending upon the fluid inclusion abundance the concentration of high temperature c derived from fluid inclusions varies from 0 1 to 66 ppm anhydrous spinel lherzolites and harzburgites generally contain

seismic activity and structural features in the charlevoix region quebec the charlevoix region is historically the most active earthquake zone in eastern canada understanding the links between its seismicity and the faults of the region is important for the assessment

multi angular reflectance properties of a hemiboreal forest an analysis using chris proba data abstract forest types differ in their hyperspectral anisotropy patterns mainly due to species specific geometrical structure spatial arrangement of canopies and subsequent shadow patterns this paper examines the multi angular hyperspectral reflectance properties of typical hemiboreal forests during summer time using three simultaneous chris proba mode 3 scenes and stand inventory data from the jarvselja training and experimental forestry district in southeastern estonia we investigated the magnitude and reasons for the differences in the anisotropy patterns of deciduous and coniferous stands at three backward viewing angles a forest reflectance model frt was used as a tool to provide a theoretical basis to the discussion and to estimate the directional contribution of scattering from crowns and ground to total stand reflectance for the two forest types the frt model simulated successfully the hdrf hemispherical directional reflectance factor curves of the study stands to match those obtained from the chris image yet it produced a smaller and less wavelength dependent angular reflectance effect than was observed in the satellite image the main results of this study provide new information for separating the spectral contribution of the forest floor or understory layer from the tree canopy layer 1 the red edge domain was identified to have the largest contribution from forest understory and 2 the more oblique the viewing angle the smaller the contribution from the understory in addition coniferous stands were observed to have a specific angular effect at the red and red edge domain possibly as a result of the hierarchical structure and arrangement of coniferous canopies

merging the minnaert k parameter with spectral unmixing to map forest heterogeneity with chris proba data the compact high resolution imaging spectrometer chris mounted onboard the project for onboard autonomy proba spacecraft is capable of sampling reflected radiation at five viewing angles over the visible and near infrared regions of the solar spectrum with high spatial resolution we combined the spectral domain with the angular domain of chris data in order to map the surface heterogeneity of an alpine coniferous forest during winter in the spectral domain linear spectral unmixing of the nadir image resulted in a canopy cover map in the angular domain pixelwise inversion of the rahman pinty verstraete rpv model at a single wavelength at the red edge 722 nm yielded a map of the minnaert k parameter that provided information on surface heterogeneity at a subpixel scale however the interpretation of the minnaert k parameter is not always straightforward because fully vegetated targets typically produce the same type of reflectance anisotropy as non vegetated targets merging both maps resulted in a forest cover heterogeneity map which contains more detailed information on canopy heterogeneity at the chris subpixel scale than is possible to realize from a single source optical data set

variability of biome reflectance directional signatures as seen by polder reflectance measurements acquired with the spaceborne polder instrument are used to analyze the variability of land surface directional signatures as a function of vegetation cover type the reflectance directional signatures are quantified by the three parameters of a modified version of the ross li reflectance model the variability of the estimated parameters with respect to the seven modis biome classes was found to be higher within the classes than between classes with the exception of the desert targets that show more isotropic reflectances a limited number of standard brdfs typically 5 in the red and near infrared capture most of the variability of the directional reflectance measurements supporting the idea that different land surfaces have similar directional signatures over vegetation targets they are characterized by a strong increase toward backscattering and much smaller variations in forward directions the results express the diversity in structural situations within a given biome class and indicate that at the resolution of the polder sensor i e a few kilometers the brdf contains little information on the dominant vegetation type we show that standard directional signatures may be used to correct the reflectance measurements for directional effects with an rms error on the order of 0 011 in the red and 0 015 in the near infrared

rare gases water and carbon in kaersutites abstract kaersutites from kakanui new zealand and from three localities in the southwestern united states have been analyzed for rare gases water and carbon to investigate the volatile signature of the sub continental mantle this study does not confirm the high 3 he 4 he and 21 ne 22 ne ratios reported by saito et al 1 for the kakanui kaersutite instead a 3 he 4 he ratio of 6 r a and atmospheric 21 ne 22 ne ratios were measured which are consistent with our current knowledge of the earth s mantle a low 40 ar 36 ar of 320 and more than 10 8 cm 3 g of 36 ar confirms the argon results of saito et al and indicates that significant quantities of 36 ar reside in this portion of the mantle kaersutites from the southwestern united states arizona have a heterogeneous helium isotope signature ranging from 8 8 r a at san carlos to 0 46 at hoover dam all d h ratios for the water in kaersutites 56 to 78 represent typical mantle values with no apparent correlation with 3 he 4 he the correlation of increasing carbon content 140 400 ppm with increasing 13 c 24 5 to 16 7 may reflect differences in the proportions of oxidized and reduced carbon in these samples

detailed seismic stratigraphy of lago puyehue implications for the mode and timing of glacier retreat in the chilean lake district lago puyehue is a glacigenic lake in the chilean lake district 40 s with a complex deglaciation history a detailed seismic stratigraphic study of its sedimentary infill indicates a much earlier retreat of the glacier from the lago puyehue basin than the neighbouring glacier from the lago rupanco basin because of their close proximity rupanco meltwater streams played an important part in the depositional processes of lago puyehue a timing discrepancy between the in lake ages of a sediment core and the outer lake ages of moraine deposits re opens the discussion on the timing of deglaciation in the southern hemisphere copyright 2011 john wiley sons ltd

classic and new dating methods for assessing the temporal occurrence of mass movements abstract establishing landslide chronologies is essential both for understanding causes of mass movements as part of fundamental geomorphological research and for the assessment of landslide hazards as part of applied geomorphology we discuss the applicability of different methods for determining landslide chronologies frequencies and dynamics in relation to the type of material being dated sampling location and type of mass movement the emphasis is on the possibilities and limitations of the different dating methods established methods such as radiocarbon dating lichenometry and dendrochronology are briefly discussed the paper focuses however on 1 new analytical techniques like accelerator mass spectrometry ams thermally ionising mass spectrometry tims and laser fusion which have led to significant improvements of established dating methods and on 2 new dating methods like optically stimulated luminescence osl dating and alpha recoil track art dating

cat scan in marine stratigraphy a quantitative approach abstract computed axial tomography cat scan gives a pseudo 3d representation of sedimentary cores sediments may be described and numerically processed from digitized high resolution images a 150 m long borehole was drilled and sampled at ile aux coudres middle estuary of the st lawrence quebec and analysed by a tomodensitometer cat scanner this borehole represents mainly the illinoian sangamonian transition series isotopic stage 5e 130 80 kyr b p of a post glacial glacioisostatic marine invasion and the subsequent regressive prodelta four representative samples 900 mm long were chosen for analysis from a transition zone between glacial and prodeltaic sediments they have been described from tomographic longitudinal and transversal sections from ct number series and also from classical analysis such as grain size organic matter and carbonates ct numbers reflect sedimentary characteristics and are closely linked to grain size and to organic matter carbonates are only weakly correlated probably because of its low concentration bed thickness and numerical processing of ct number series are used to characterize lamina and allow for depicting sub annual annual and longer periodicities clay facies fine and thick rhythmites and isolated diamicton beds were identified from bottom to top the first sample contains homogeneous clay rhythmites typical of a distal environment the second is composed of diamictons and thin alternating light dark annual lamina sets in the third sample annual light dark rhythmites are slightly thicker and display subtle semi annual cyclicities in the fourth sample annual rhythmites are several centimetres in thickness and contain preserved sub annual events of possible seasonal cyclicity this succession of facies and associated stratal periodicities may be typical of transgressive sedimentation in a basin such as the st lawrence estuary during the transition from glacial to non glacial conditions

strategies for high temperature oxygen isotope thermometry a worked example from the laramie anorthosite complex wyoming usa abstract an understanding of the factors that affect the magnitude and direction of isotopic exchange is fundamental to the application of oxygen isotope geothermometers this is particularly true in high temperature rocks where retrograde exchange between minerals commonly results in the calculation of spurious isotopic temperatures herein we present an approach to isotope thermometry that combines numerical modelling techniques with a directed sampling strategy to retrieve peak or near peak temperature information from rocks that have behaved as closed systems on the hand sample scale during cooling the isotopic composition of minerals in such samples changes in predictable fashion on cooling these so called isotope exchange trajectories iet can be calculated for any mineral given the whole rock isotopic composition the modal abundance of each mineral in the rock and the fractionation factors between the minerals model temperatures can be obtained for both single and multiple hand samples through the calculation of iets temperatures for single samples are determined by locating the intersection between a mineral s calculated iet and its measured isotopic composition on plots of 18 o vs 1 t 2 the resulting temperature represents either the closure temperature of the mineral or the maximum temperature attained by the rock whichever is lower the multiple sample method relies on the premise that at high temperatures isotopic equilibrium is effectively achieved over a large area typically on the scale of meters or larger this method permits the retrieval of temperatures that are significantly higher than the closure temperature of any individual mineral multiple sample temperatures are calculated by determining the intersection of the iets of a given mineral in two or more samples the intersection of these iets represents the temperature at which the isotopic composition of the mineral was the same in both samples i e the last temperature of large scale isotopic equilibrium our methods allow for a rigorous determination of uncertainties in the calculated temperatures these numerical techniques can be used on any samples precise temperature estimates however require samples with specific mineralogic and modal characteristics the best samples for use with the single sample method are those that contain small amounts of a slow diffusing mineral and large fractionation factors between this mineral and the other minerals in the rock the multiple sample method requires two or more samples with widely different modal proportions of a mineral that strongly fractionates oxygen isotopes such samples are present in many terrains but are commonly overlooked because their mineral assemblages are not well suited for conventional thermobarometry these methods yield excellent results when applied to rocks from the sybille fe ti oxide quarry a late magmatic segregate of the laramie anorthosite numerical modelling of single sample and multiple samples from this quarry yield temperatures of 1000 and 1080 c respectively the single sample temperatures record the closure temperature of ilmenite whereas the multiple sample temperatures correspond closely to the experimentally determined solidus for these rocks these model temperatures are higher than any other conventional oxygen isotope temperatures yet reported from slowly cooled rocks

the sources of water in martian meteorites clues from hydrogen isotopes abstract h isotope measurements of carbonate phosphate feldspathic and mafic glasses and post stishovite silica phase in the shergottites zagami shergotty sau 005 dag 476 alha 77005 and eeta 79001 as well as in chassigny and alh 84001 show that all these phases contain deuterium enriched water of extraterrestrial origin the minerals and glasses analyzed may contain an initial primary hydrogen component but their isotopic composition was modified to varying degrees by three different processes interaction with a fractionated exchangeable water reservoir on mars hydrogen devolatilization by impact melting and terrestrial contamination positive correlations between d and water abundance in feldspathic glass and post stishovite silica in zagami shergotty and sau 005 is indicative of mixing of a high d component 3000 4000 and a less abundant low d component 0 the high d component is primarily derived from the martian exchangable reservoir but may also have been influenced by isotopic fractionation associated with shock induced hydrogen loss the low d component is either a terrestrial contaminant or a primary magmatic component the negative correlation between d and water abundances in mafic and feldspathic glasses in alh 84001 alha 77005 and eeta 79001 is consistent with the addition of a low d terrestrial contaminant to a less abundant high deuterium martian component the low d of magmatic glass in melt inclusions suggests that the d of martian parent magma was low and that the initial h isotope signature of mars may be similar to that of earth

postglacial sequence stratigraphy of lake melville labrador abstract in lake melville labrador the quaternary glacimarine sediments reflect a single retreat phase of the laurentide ice sheet during the early holocene based on extensive airgun and high resolution seismic surveys sediment deposits are subdivided into thirteen units that are associated with glacial paraglacial and postglacial styles of deposition their distribution patterns reflect paleo positions of a retreating ice margin during the period between 10 000 and 9000 years before present formation of paraglacial deltas during the early to mid holocene 6 9 ka and postglacial tidal influenced deposition during the late holocene

oxygen and carbon isotope composition of structural carbonate in weathering apatites from laterites southern brazil and western senegal abstract the oxygen 18 o c and carbon 13 c c isotope compositions of the structural carbonate group co 3 in apatites from lateritic profiles were investigated the weathering profiles located in southern brazil and in western senegal are developed on three different types of apatite rich parent rock carbonatite metamorphosed marine phosphorite and sedimentary marine phosphorite the parent rock apatites are of magmatic hydrothermal metamorphic and sedimentary origins the in situ formation of apatite of weathering origin in the profiles is well documented petrographically and geochemically the overall range of measured 18 o c and 13 c c values of apatites of weathering origin 22 to 27 smow for 18 o c and 15 to 10 pdb for 13 c c is much smaller than the range of measured and or published isotope compositions of parent rock apatites 4 35 for 18 o c and 11 to 1 for 13 c c in any profile the apatites of weathering origin can exhibit lower similar or higher 18 o c values than parent rock apatites in contrast their 13 c c values are systematically and significantly lower than those of the parent rock apatites apatites formed as a result of weathering in laterites can therefore be readily distinguished from apatites of other origin on the basis of their isotope composition assuming that apatite co 3 fractionates o in a way similar to calcite co 3 the structural carbonate group of the apatites of weathering origin appears to form in approximate isotopic equilibrium with the weathering solutions the very low 13 c c values exhibited by these apatites indicate that the dominant sources of dissolved co 2 in the soil water are organic the isotope composition of structural carbonate in apatite of weathering origin in lateritic profiles may provide useful information for paleoenvironmental studies

characterization of surface heterogeneity detected at the misr terra subpixel scale vegetation structure can have a significant impact on the degree of anisotropy in the reflected radiation field with the appropriate characterization of these effects the analysis of multiangular data such as provided by the multi angle imaging spectroradiometer misr instrument on board terra can yield statistical information about the type of surface heterogeneity that exists at the subpixel scale

a high resolution seismic stratigraphy from a scottish sea loch and its implications for loch lomond stadial deglaciation a detailed high resolution seismic stratigraphy calibrated by core data and terrestrial geomorphological mapping has been constructed for loch ainort isle of skye this study has provided a palaeoenvironmental history of the area as well as important corroborative evidence for the stepped deglaciation of the loch lomond stadial ice field on skye the ainort glacier reworked pre loch lomond glacial deposits terminating in a grounded tidewater ice front potentially 800 m beyond the previously extrapolated limit the first stage of deglaciation was characterised by the formation of de geer moraines indicative of a period of interrupted retreat the second phase by contrast produced hummocky relief with sporadic linear moraines suggesting periods of uninterrupted retreat with occasional stillstands readvances paraglacial reworking of terrestrial slopes resulted in the deposition of thick subaqueous debris flows which graded into fluvioglacial dominated sediments and ultimately modern fjordic deposits the identification of an initial period of active retreat punctuated by numerous readvances correlates directly with the terrestrial record however the offshore stratigraphy suggests that although the second phase was dominated by uninterrupted retreat occasional stillstands readvances did occur

hydrogen isotope systematics of submarine basalts the d h ratios and water contents in fresh submarine basalts from the mid atlantic ridge the east pacific rise and hawaii indicate that the primary d h ratios of many submarine lavas have been altered by processes including 1 outgassing 2 addition of seawater at magmatic temperature and 3 low temperature hydration of glass decreases in d and h2o from exteriors to interiors of pillows are explained by outgassing of water whereas inverse relations between d and h2o in basalts from the galapagos rise and the famous area are attributed to outgassing of ch4 and h2 a good correlation between d values and h2o is observed in a suite of submarine tholeiites dredged from the kilauea east rift zone where seawater added directly to the magma affected only the isotopic compositions of hydrogen and argon analyses of some glassy rims indicate that the outer millimeter of the glass can undergo lowtemperature hydration by hydroxyl groups having d values as low as 100 d values vary with h2o contents of subaerial transitional basalts from molokai hawaii and subaerial alkali basalts from the society islands indicating that the primary d values were similar to those of submarine lavas extrapolations to possible unaltered d values and h2o contents indicate that the primary d values of most thoteiite and alkali basalts are near 80 5 the weight percentages of water are variable 0 15 0 35 for mor tholeiites about 0 25 for hawaiian tholeiites and up to 1 1 for alkali basalts the primary d values of 80 for most basalts are comparable to those measured for deep seated phlogopites these results indicate that hydrogen in marked contrast to other elements such as sr nd pb and o has a uniform isotopic composition in the mantle this uniformity is best explained by the presence of a homogeneous reservoir of hydrogen that has existed in the mantle since the very early history of the earth

late glacial and holocene sedimentary environments of quesnel lake british columbia abstract at 512 m quesnel lake is the third deepest in north america and at 100 km long its drainage basin spans from the arid interior plateau to the high mountains of the eastern cordillera where small glaciers are a significant source of sediment in most of the lake sediment is 0 to 40 m thick reaching a maximum of just over 100 m thick near the junction of the three arms cores from three locations in the lake provide evidence that the entire holocene record is contained in the upper 4 to 6 m of the sedimentary record where rates of accumulation have been constant or have decreased slowly the highest rates 0 35 to 0 72 mm a occur near points of inflow while the lowest rate 0 22 mm a occurs in a sheltered environment with limited inflow and significant hypolimnic circulation which may flush water and suspended sediment from the water column late pleistocene sediment beneath has a similar acoustic signature to the cored holocene record above suggesting that the sedimentary processes governing its deposition were not greatly different than in the present lake but that extensive glacial and paraglacial sources contributed to a significantly higher rate of accumulation mazama ash analyzed from two locations near points of inflow has an age of 7576 60 cal bp according to our chronology vivianite which is uncommon in lakes of the cordillera occurs in the middle of the cores mainly associated with macroscopic wood fragments and indicates reducing conditions within the sediment

hydrogen and d h analysis of apatite by elemental analyzer chromium high temperature conversion isotope ratio mass spectrometry ea cr htc irms abstract hydrogen and d measurements of the mineral apatite have been used to measure volatile contents of planets and planetesimals and to infer the sources and evolution of water throughout the solar system all of these studies use secondary ion mass spectrometry sims which necessitates the use of apatite mineral standards to correct for matrix effects which have previously been measured by mass spectrometry for hydrogen isotopes here we present a new technique of elemental analyzer chromium high temperature conversion isotope ratio mass spectrometry ea cr htc irms for the measurement of hydrogen and hydrogen isotopes of apatite this technique presents greater technical advantages over tc ea due to ability of chromium to bind with phosphorus in the high temperature reactor and prevent this elemental p from clogging the instrument components we also show that removal of adsorbed moisture of nominally hydrous minerals and glasses becomes increasingly important with decreasing grain size of materials and present experiments on moisture removal from nominally anhydrous quartz we report hydrogen and hydrogen isotope results of five fluorapatite and two hydroxylapatite samples including durango apatite we show that our results of hydrogen content of durango apatite are similar to published values using the tc ea technique our recommended values for hydrogen using a cr reactor for h2o and dvsmow slap for durango apatite are 608 102 ppm h2o and dvsmow slap 86 4 2

high resolution seismic reflection profiling of neotectonic faults in lake timiskaming timiskaming graben ontario quebec canada the timiskaming graben is a 400 km long 50 km wide north west trending morphotectonic depression within the canadian shield of eastern north america and experiences frequent intraplate earthquakes the graben extends along the border of ontario and quebec connecting southward with the nipissing and ottawa bonnechere grabens and the st lawrence rift system which includes a similar structure underlying the hudson valley of the eastern usa together they form a complex failed rift system related to regional extension of north american crust during the breakup of rodinia and later pangea the timiskaming graben lies within a belt of heightened seismic activity western quebec seismic zone with frequent moderate magnitude greater than magnitude 5 earthquakes including a magnitude 6 2 in 1935 these events threaten aging urban infrastructure built on soft glacial sediments post glacial landslides along the ottawa valley suggest earthquakes as large as magnitude 7 the inner part of the timiskaming graben is filled by lake timiskaming a large 110 km long post glacial successor to glacial lake barlow that was ponded by the laurentide ice sheet 9500 years ago the effects of frequent ground shaking on lake floor sediments was assessed by collecting more than 1000 line kilometres of high resolution chirp seismic profiles late glacial lake barlow glaciolacustrine and overlying post glacial sediments are extensively deformed by extensional faults that define prominent horsts and grabens multibeam bathymetry data suggest that faults influence the morphology of the modern lake floor despite high sedimentation rates and indicate recent neotectonic deformation the lake timiskaming area provides evidence of post glacial intracratonic faulting related to recurring earthquake activity along a weak spot within the north american plate

mapping shrub abundance in desert grasslands using geometric optical modeling and multi angle remote sensing with chris proba this work examines the application of a geometric optical canopy reflectance model to provide measures of woody shrub abundance in desert grasslands at the landscape scale the approach is through inversion of the non linear simple geometric model sgm against 631 nm multi angle reflectance data from the compact high resolution imaging spectrometer chris flown on the european space agency s project for on board autonomy proba satellite separation of background and upper canopy contributions was effected by a linear scaling of the parameters of the walthall bidirectional reflectance distribution function model with the weights of a kernel driven model the relationship was calibrated agains ta small number of sample locations with highly contrasting background upper canopy configurations before application over an area ofabout 25 km 2 the results show that with some assumptions the multi angle remote sensing signal from chris proba can be explained in terms of a combined soil understory background response and woody shrub cover and exploited to map this important structural attribute of desert grasslands

late quaternary morphostratigraphy of lake st joseph southeastern canadian shield evolution from a semi enclosed glacimarine basin to a postglacial lake abstract this paper reports and describes multibeam echosounder subbottom profiler and sediment sampling data collected in lake st joseph southern quebec a formerly glacimarine sedimentary basin that has been glacio isostatically uplifted to form a small lake its study provides a unique opportunity for investigating changes in sedimentary environments from a glacial sea to a postglacial lake multibeam bathymetry allows the observation of two basins separated by a bathymetric ridge and of mass movement deposits in both basins high resolution seismic stratigraphy reveals the presence of seven seismic units these seven units relate to the advance and retreat of the laurentide ice sheet over the region following ice retreat transparent u3 and high amplitude reflection u4 units were deposited during the champlain sea invasion the transparent unit likely represents a rapidly retreating glacier which allowed the deposition of massive silt and clay whereas the high amplitude reflectors which are internally composed of transparent to chaotic lenses are interpreted as the result of a deceleration of ice retreat or a stabilization of the glacier and of glacio isostatic rebound overlying the champlain sea sediments a unit composed of smaller laminations u5 suggests that it was deposited during the marine to lacustrine transition in a paraglacial environment this is supported by its presence in the northern basin where the riviere aux pins mouth is located and its absence in the southern basin where no river is observed the bathymetric ridge between the two basins thus limited sediment transport following the complete retreat of the champlain sea organic rich sediments u7 were deposited in the lake in the northern basin the presence of the riviere aux pins allowed their deposition in the form of rhythmites whereas the absence of rivers in the southern basin resulted in the deposition of an acoustically transparent unit a mass movement u6 identified during the deposition of unit 7 occurred around 1250 ad and is interpreted as earthquake triggered

late stage volatile saturation as a potential trigger for explosive volcanic eruptions magma reservoirs typically accumulate over hundreds to thousands of years yet geochemical analyses of volcanic rocks from campi flegrei suggest activity there was triggered by injections of volatile rich magma only days before the eruption

low carbon isotope ratios in apatite an unreliable biomarker in igneous and metamorphic rocks abstract carbon isotope ratios of apatite have been used to interpret the source of carbon in magmas and metamorphic fluids using the assumption that carbon isotope fractionations between phases are small in igneous and metamorphic systems measured carbon isotope fractionations between co existing apatite and calcite from igneous metaigneous and metasedimentary rocks are large and variable 13c 2 3 to 20 8 reflecting variability in 13c ap sampled by combustion this result indicates that carbon isotopes in apatite sampled by common techniques combustion ion microprobe step heating do not have a straightforward interpretation these data suggest that the low 13c values in apatite that have previously been used as indicators of biological activity may be the result of the carbon isotope fractionation systematics of apatite rather than a reflection of incorporation of organic carbon this unusual fractionation behavior may require reconsideration of the significance of low 13c carbonaceous inclusions in apatite from 3 8 ga metamorphic rocks from akilia island greenland

seismic stratigraphy buried beach ridges and contourite drifts the late quaternary history of the closed lago cardiel basin argentina 49 s the results of a seismic stratigraphic analysis of a closed lake basin lago cardiel in southernmost south america are reported very few high resolution continental records spanning the late quaternary have been obtained from this region seismic sequence stratigraphic analysis allows a reconstruction of lake level variations two major hiatuses of unknown age occurred during the early evolution of the basin with the deposition of an alluvial fan in a restricted area in the intervening time period following the development of a relatively shallow lake during the late pleistocene and a short desiccation pulse around 11 220 14c yr bp a transgression of over 135 m occurred at the beginning of the holocene the transgression was associated with the formation of beach ridges preserved in the lake stratigraphy on the floor of the modern lago cardiel at four different elevations the preservation of largely unreworked beach ridges indicates a stepwise rise in the lake level there is no seismic evidence of a major lowering of the lake below modern level during the entire holocene deposition since the mid holocene is marked by strong lateral differences in sediment accumulation with a depocentre slightly to the north of the basin midpoint and a pronounced mounded distribution seismic reflection geometries as well as sedimentological characteristics indicate a lacustrine contourite drift covering an area of 80 100 km2 as lago cardiel is under the influence of westerly winds these most likely drove lake circulation the identification of drowned beach ridges and of contourite drifts illustrates that high resolution seismic stratigraphy is not only a powerful tool in reconstructing past lake level elevations for closed lake basins but it can also provide information about the rate of lake level changes and the presence and strength of lake currents

deuterium and 37 chlorine rich fluids on the surface of mars evidence from the enriched basaltic shergottite northwest africa 8657 abstract apatite a major hydrous mineral in martian meteorites has the potential to reveal history of volatiles on mars here we report the h and cl isotopic systematics of apatite from the enriched basaltic shergottite nwa 8657 to better understand the processes influencing volatiles at or near the martian sub surface the apatite in nwa 8657 has the highest reported d value up to 6509 of any phosphates in martian meteorites the positive correlation between the h2o contents 72 2251 ppm and d values 3965 6509 as well as between the cl contents 1 28 6 17 wt and 37cl values 1 7 4 0 in nwa 8657 apatite are consistent with mixing between volatiles derived from the martian mantle and meteoric water fluid the d and 37cl enrichment of apatite in nwa 8657 implies isotopic exchange with sub surficial fluids during post crystallization hydrothermal event s plain language summary mars was probably a wet and warm world during its earliest geological history supported by many lines of evidence present day mars is cold and arid although recent remote sensing data support the existence of subsurface glaciers and seasonal fluid activities at some locations in this study our aim was to use ground truth about the potential water rock interaction on or near surface environments on recent mars via measuring the h and cl isotopic compositions of apatite from a geologically young meteorite from mars the enriched basaltic shergottite nwa 8657 the petrography and mineral chemistry of apatite and other associated phases e g merrillite maskelynite mesostasis and pyroxene were documented prior to in situ h and cl isotopes analysis the water contents of apatite merrillite maskelynite mesostasis and pyroxene are positively correlated with the d values all of the datasets can be reconciled in terms of mixing between two endmembers a d poor 0 mantle reservoir and a d rich 5920 500 near surface underground water reservoir moreover apatite in nwa 8657 displays 37cl enriched 1 1 in average characteristics these signatures are consistent with d and 37cl rich fluid assisted isotopic exchange in recent near surface environment on mars

effects of strong seismic shaking in lake sediments and earthquake recurrence interval temiscaming quebec the magnitude 6 3 timiskaming earthquake of 1935 resulted in discoloration in small lakes in the epicentral region sonar profiles for lac tee have shown that organic rich gyttja has been removed from the sides and redeposited in the deep parts of the lake lake sediment cores from deep basins contain a 2 3 cm uppermost layer which is interpreted as the normal accumulation of sediment since 1935 this is followed by a 20 cm chaotic zone of black gyttja mixed with partly tabular fragments of a previously formed silt layer underlain by a dense 1 2 cm thick silt horizon the latter is interpreted as having formed by rapid settling of the denser silicate portion of the resuspended sediment this 20 cm zone is insufficient to account for the abnormal thickness of gyttja in the basins so events of this kind would have had to have occurred repeatedly since deglaciation the only major prehistoric event revealed by these 100 cm cores is at a depth equivalent to about 1500 years ago based on the amount of sed

geophysical surveys of the sediments of loch ness scotland implications for the deglaciation of the moray firth ice stream british irish ice sheet we present results from three geophysical campaigns using high resolution sub bottom profiling to image sediments deposited in loch ness scotland sonar profiles show distinct packages of sediment providing insight into the loch s deglacial history a recessional moraine complex in the north of the loch indicates initial punctuated retreat subsequent retreat was rapid before stabilisation at foyers rise formed a large stillstand moraine here the calving margin produced significant volumes of laminated sediments in a proglacial fjord like environment subsequent to this ice retreated rapidly to the southern end of the loch where it again deposited a sequence of proglacial laminated sediments sediment sequences were then disturbed by the deposition of a thick gravel layer and a large turbidite deposit as a result of a jo kulhlaup from the spean roy ice dammed lake these sediments are overlain by a holocene sheet drape data indicate i a former tributary of the moray firth ice stream migrated back into loch ness as a major outlet glacier with a calving margin in a fjord like setting ii there was significant sediment supply to the terminus of this outlet glacier in loch ness and iii that jo kulhlaups are important for sediment supply into proglacial fjord lake environments and may compose 20 of proglacial sedimentary sequences

stable carbon and oxygen isotope analysis of fossil tooth enamel using laser ablation abstract a technique is described whereby the 13c and 18o values of fossil tooth enamel can be measured in situ using laser ablation techniques the laser heats the sample and forms co2 from structural carbonate apatite the 18o values obtained with this method are equal to those of the phosphate oxygen due to the high temperature of reaction during ablation analytical precision is approximately 0 5 for both 13c and 18o the spatial resolution is 200 m or less which may be reduced as the technical modifications are made this method allows the analysis of samples that previously could not be analyzed due to difficulty with sample preparation size or rare nature the apparent oxygen isotope fractionation between the carbonate and laser derived oxygen co3 laser is 1 0071 for biogenic apatite at 38 c determined using the in situ laser comparison of 18o co3 and 18o laser analyses with 18o laser and 18o po4 results suggest a fractionation factor co3 po4 of 1 0083 variations in the 18o and 13c values of single teeth can be easily determined with the in situ technique this will allow the study of changes in diets or water sources during the period of tooth growth which for larger mammals can be several years for the tooth row the 13c and 18o values are important in paleodiet and paleoecology studies they can be used to study resource partitioning within an ecosystem and can shed light on the life history strategies within living and extinct species

stable isotope o h s relationships in tertiary basalts and their mantle xenoliths from the northern hessian depression w germany 18o 16o 34s 32s and d h ratios as well as vacuum fusion h2o contents were measured for late tertiary volcanic basaltic rocks ranging in composition from quartz tholeiites and alkali olivine basalts to melilite bearing olivine nephelinites and for peridotite xenoliths from the northern hessian depression of w germany measured oisotope ratios in both basalts and peridotites were corrected for variable degree of post eruption secondary alteration the ranges and means of corrected 18o values smow for the north hessian lavas and peridotites are i 8 tholeiites ca 6 1 to 7 3 x 6 6 ii 21 alkali olivine basalts ca 5 4 to 7 6 x 6 5 iii 19 nepheline basanites limburgites and olivine nephelinites ca 5 3 to 8 0 x 6 6 and iv 23 peridotites 5 1 to 7 0 x 6 0 the 34s values cdt for the tholeiites range from 0 6 to 1 4 x 0 03 and for the alkali basalts range from 0 9 to 8 6 x 2 5 the approximate d value smow of the pristine basalts and peridotites is estimated to have been ca 90

wurmian deglaciation of western lake geneva switzerland based on seismic stratigraphy abstract western lake geneva le petit lac was filled during the quaternary over a major erosion surface truncating the cemented folded and thrusted tertiary sediments of the foreland alpine basin the carving of the lake occurred during quaternary glaciations with ice originating from the rhone valley catchment basin flowing in two branches oriented sw and ne over the swiss plateau lake geneva is situated on the south western branch of this paleo ice cap for the first time a dense grid of high resolution seismic profiles airgun 5 inch3 airgun 1 inch3 and echosounder has imaged the whole quaternary sequence providing a paleoenvironmental interpretation and a detailed reconstruction of the rhone glacier retreat stages during glacial events that led to the formation of western lake geneva the quaternary sequence filling up the bedrock valley is exceptionally thick with up to 220 m of deposits and consists of glacial glacio lacustrine and lacustrine sediments fourteen seismic units have been defined units u1 u14 unit u1 represents the remnants of glacial deposits older than the last glacial cycle preserved in the deepest part of the lake and in secondary bedrock valleys unit u2 represents gravel and sands deposited by meltwater circulation at the bottom of the glacial valley unit u3 is a thick stratified unit marking the beginning of the deglaciation when the rhone glacier became thinner and buoyant and allowed the formation of a subglacial lake younger glacial units units u4 u5 u7 u9 u11 are acoustically chaotic sediments deposited subglacially under the water table undermelt tills while the glacier was thinning these glacial units are bounded by synform erosion surfaces corresponding to readvances of the glacier the transition from a glacial to a glacio lacustrine environment started with the appearance of a marginal esker fan system unit u6 esker formation was followed by a small advance retreat cycle leading to the deposition of unit u7 then the ice front receded and stratified sediments were deposited in a glacio lacustrine environment units u8 u10 and u12 this retreat was punctuated by two readvances coppet unit u9 and nyon unit u11 producing large push moraines and proglacial debris flows finally a lacustrine environment with a characteristic lake current pattern and mass movement deposits took place units u13 and u14 except for unit u1 the sedimentary sequence records the wurmian deglaciation in a fjord like environment occupied by a tidewater glacier with a steep calving ice front the presence of an esker fan system reveals the importance of subglacial meltwater flow in continental deglaciation push moraines and erosion surfaces below the glacier indicate at least 5 readvances during the deglaciation thus revealing that oscillations of ice front are the key process in deglaciation of perialpine fjord lakes the dating of these continental glacier fluctuations would allow correlation with oceanic and ice records and help to understand the climatic mechanisms between oceans and continents

documentation of earthquake induced disturbance of lake sediments using subbottom acoustic profiling subbottom acoustic profiling in lakes on the canadian shield and in the canadian cordillera has revealed disruptions in deltaic and lacustrine sediments that can be attributed to large historical earthquakes the timiskaming earthquake of 1935 magnitude 6 25 and the vancouver island earthquake of 1946 magnitude 7 2 triggered extensive slumping and flow of postglacial sediments in lakes located within a few tens of kilometres of the epicentres of these events there is some evidence in one of the surveyed lakes for in situ mobilization of sediment on relatively gentle slopes with minimal horizontal displacement this may be a product of liquefaction induced by coseismic shaking or displacements along faults beneath the basin in another lake widespread coseismic slumping resuspended large amounts of fine sediment which then settled out onto the lake floor to produce a texturally anomalous layer features similar to those produced by the 1935 and 1946 earthquakes can also result from a variety of non

retrieving photometric properties of desert surfaces in china using the hapke model and misr data abstract the retrieval of photometric properties of desert surfaces is an important first step in the parameterization of land surface components of regional dust emission and global radiation models and in earth system modeling in this study the values of hapke s photometric parameters h b c b0 and were retrieved from the multi angle imaging spectroradiometer misr instrument at locations in china s deserts four pixels represented the typical surface characteristics of the taklimakan desert sand dunes of kumtag desert relatively smooth areas of the kumtag desert and the aeolian sandy soil of loulan in contrast to earlier studies we found that the retrieved parameter values were largely affected by the initial value to combat this problem we used a monte carlo method with physical constraints and a conformity indicator to ensure physically meaningful inversion the results showed that the angular domain of misr observations was sufficiently large to determine confidently the values of hapke s photometric parameters with the exception of the opposition effect width h retrieved values for the single scattering albedo and macroscopic roughness were consistent with qualitative observations about the structure and composition of the surface material and the nature of the dune forms respectively at loulan where the surface was smoother than other sites retrieved values exhibited the strongest backward scattering these results indicated that at the sensor scale a rough surface e g dunes does not necessarily mean more backward scattering than a smooth surface this finding has significant implications for empirical methods e g using the normalized index of backward scattered radiance minus forward scattered radiance as an indicator to indicate surface roughness which should be used carefully for analyzing surface roughness from remote sensing data future research is needed to 1 understand how surface roughness at the sub pixel scale modifies the angular characteristics of reflectance and to 2 find practical methods for rapid whole image processing for mapping the photometric parameters

identification and dating of a key late pleistocene stratigraphic unit in the st lawrence estuary and gulf eastern canada abstract a recently acquired 8 m long sediment core along with high resolution seismic reflection and subbottom profiler sections allowed the identification characterization and dating of a widespread seismic unit extending from the head of the laurentian channel lower st lawrence estuary to honguedo strait gulf of st lawrence eastern canada this seismic unit labelled unit 2 is characterized by a series of parallel high amplitude reflections with thicknesses ranging from 68 m near the head of the laurentian channel to 250 m in the st lawrence estuary leaving it very difficult to be reached by conventional coring operations here we reveal how we were able to trace and core this seismic unit in an area where it lays closer to the seafloor near the southern wall of the laurentian channel in the lower st lawrence estuary this seismic unit consists of two sedimentary facies sandy mud including ice rafted debris ird underlying faintly laminated to homogenous and plastic silty clays based on the sedimentary facies we interpret the upper clays as ice distal glaciomarine sediments and the lower sandier sediments as ice proximal glaciomarine sediments this interpretation is further supported by the fact that no seismic nor sediment facies present above seismic unit 2 throughout the estuary and gulf of st lawrence can be linked to glacial i e ice contact sediments such as till moraines esker etc sediments seismic unit 2 is highly disturbed by iceberg scouring in the gulf of st lawrence where it is found at shallower depths indicating that it was deposited during deglaciation the available ams 14c dates obtained in the ice proximal glaciomarine sediments indicate that the lower part of seismic unit 2 was deposited during local re advances or stillstands of the laurentide ice sheet margins in the goldthwait sea that began at or before the younger dryas cold event 11 100 10 000 yr bp and that seismic unit 2 can be used as a chronostratigraphic marker throughout the st lawrence estuary and northwestern gulf of st lawrence

2300 yr history of seismicity from silting events in lake tadoussac charlevoix quebec silt layers in organic rich lake sediments are interpreted to represent the historic earthquakes of 1638 1663 1791 1870 and 1925 of the charlevoix region of eastern canada this interpretation is based on the relative spacing of the layers and the accelerator mass spectrometer sup 14 c dating of a twig in one of the cores the silt layers were presumably caused by landslides on tributary streams and by resuspension of the sediment the cores contain up to 22 layers 1 to 45 mm thick over a depth equivalent to about 2300 yr if there is a correlation between thickness and magnitude there would have been four events of richter magnitude 7 5 or greater in a d 1663 1320 60 and 320 b c the 18 other layers could correspond to earthquakes of magnitude 6 to 7 the recurrence interval from 300 b c to a d 800 is 120 yr followed until a d 1500 by a quiet period when there was a single large event the recurrence interval from a d 1500 to the present is 75 yr

magmatic fluids in the fen carbonatite complex s e norway three different types of carbonatite magma may be recognized in the cambrian fen complex s e norway 1 peralkaline calcite carbonatite magma derived from ijolitic magma 2 alkaline magnesian calcite carbonatite magma which yielded biotite amphibole sovite and dolomite carbonatite and 3 ferrocarbonatite liquids related to 2 and or to alkaline lamprophyre magma damjernite apatite formed during the pre emplacement evolution of 2 contains inclusions of calcite and dolomite devitrified mafic silicate glass and aqueous fluid all of these inclusions have a magmatic origin and were trapped during a mid crustal fractionation event p 4 kbars t 625 c where apatite and carbonates precipitated from a carbonatite magma which coexisted with a mafic silicate melt the fluid inclusions contain water dissolved ionic species mainly nacl with minor polyvalent metal salts and in some cases co2 two main groups of fluid inclusions are recognized type a co2 bearing inclusions of approximate molar composition h2o 88 90 co 27 5 nacl 5 d 0 85 0 87 g cm3 type b co2 free aqueous inclusions with salinities from 1 to 24 wt nacleq and densities betwen 0 7 and 1 0 g cm3 more strongly saline type b inclusions salinity ca 35wt d 1 0 to 1 1 g cm3 contain solid halite at room temperature and occur in overgrowths on apatite type a inclusions probably contain the most primitive fluid from which type b fluids have evolved during fractionation of the magmatic system type b inclusions define a continuous trend from low towards higher salinities and densities and formed as a result of cooling and partitioning of alkali chloride components in the carbonatite system into the fluid phase available petrological data on the carbonatites show that the fluid evolution in the fen complex leads from a regime dominated by juvenile co2 h2o fluids during the magmatic stage to groundwater derived aqueous fluids during post magmatic reequilibration

the implication of the oxygen isotope records in coexisting cherts and phosphates 18 o values have been determined for 53 coexisting chert phosphate pairs from the phanerozoic and precambrian in addition 18 o values were also determined for 18 biogenic phosphates from the phanerozoic the oxygen isotope data for the chert phosphate pairs permit the calculation of the temperatures of formation of the chert phosphate pairs as well as the 18 o of the waters in which they equilibrated in turn the calculated 18 o of the waters permit the calculation of temperatures from the isotopic data of the biogenic phosphates the temperatures for the tertiary and mesozoic samples are compatible with the literature values determined from oxygen isotope data for well preserved calcareous marine skeletal remains the temperatures calculated from the chert phosphate pairs of the paleozoic are usually higher and vary in cycles of about a 150 million year period the early precambrian temperatures are as high as 80 c and decrease with time the use of chert phosphate pairs for temperature determinations are sufficiently promising to warrant further investigations of this type on well preserved chert phosphate or carbonate phosphate pairs

contribution palynostratigraphique dinokystes pollen et spores a la connaissance de la mer de champlain coupe de saint cesaire quebec high resolution continental pollen and spores and marine dinoflagellate cysts microfloral records were obtained from a section consisting of about 0 5 m of glaciolacustrine and 2 5 m of champlain sea deposits at the saint cesaire site the pollen and spore assemblages indicate the existence of a regional open vegetation of shrub tundra to forest tundra fluctuations in the percentages of picea and shrub and herb taxa are related to regional afforestation and paleogeographical evolution of the basin the champlain sea sediments contain an abundant dinocyst flora dominated by operculodinium centrocarpum brigantedinium spp and algidasphaeridium minutum which indicate cold arctic conditions in surface waters fluctuations in concentration 102 104 cm 3 and relative abundance of dinocyst species are attributed to changes in dinoflagellate productivity and paleoceanographic conditions notably paleosalinity morphological variations of operculodinium centrocarpum and algidasphaeridium minutum led to

compositional variation of apatite from rift related alkaline igneous rocks of the gardar province south greenland textural and compositional variations of apatite from rift related gabbros syenogabbros syenites quartz syenites and nepheline syenites of the mid proterozoic gardar province south greenland are presented and compared to apatite compositions from other rock suites the observed zoning textures of apatite are interpreted to represent 1 primary growth zonation concentric and oscillatory that formed during magmatic differentiation and 2 secondary irregular overgrowths patchy zonation and resorption textures assigned to metasomatic overprinting due to interaction with fluids melts and intra crystalline diffusion compositional variation in the apatites is mainly due to coupled substitutions of ca and p by variable amounts of si na and ree which show increasing concentrations during magmatic differentiation furthermore f concentrations in apatites increase from gabbroic through syenogabbroic to syenitic rocks whereas cl concentrations show the opposite trend compared to apatite compositions from gabbroic dioritic and granitic rocks in general apatites from alkaline rock suites are characterized by exceptionally high contents of ree and si and in some alkaline rocks they attain sr contents comparable to those reported from carbonatites typical low mn and s contents are probably a result of low oxygen fugacity during crystallization at relatively high temperatures

uniqueness of multiangular measurements i an indicator of subpixel surface heterogeneity from misr the recent availability of quasi simultaneous multispectral and multidirectional measurements from space as provided by the multi angle imaging spectroradiometer misr on board the terra platform offers new and unique opportunities to document the anisotropy of land surfaces at critical solar wavelengths this paper presents simple physical principles supporting the interpretation of the anisotropy of spectral radiances exiting terrestrial surfaces in terms of a signature of surface heterogeneity the shape of the anisotropy function is represented with two model parameter values which may be mapped and interpreted in their own right the value of one of these parameters also permits identifying geophysical conditions where the surface heterogeneity becomes significant and where three dimensional 3d radiation transfer effects have to be explicitly accounted for this paper documents these findings on the basis of results from a number of 3d radiation transfer model simulations the latter are used to perform an extensive sensitivity study which includes issues related to the scale of investigation a preliminary validation of these results conducted with a dataset collected by the airmisr instrument over the konza prairie is also discussed

application de la scanographie a l etude de la densite des sediments et a la caracterisation des structures sedimentaires exemple des sediments deposes dans la riviere saguenay quebec canada apres la crue de juillet 1996 following the flood of july 1996 a significant quantity of sediment coming from the catchment areas contiguous to the saguenay fjord was discharged in the baie des ha ha and the north arm to characterize the mode of deposit and the potential for remobilization of these deposits a series of cores was taken in the fjord using a box corer and a gravity corer during the summers of 1997 and 1998 these cores have been analyzed by the axial tomodensitometer at the regional hospital center of rimouski the use of the tomodensitometer in geology allows a nondestructive study of the sample and a qualitative and quantitative evaluation of the density of the sediments their mode of deposition and their compaction the study of the upper 45 cm of sediments shows the presence in the uppermost layer of several facies type characteristics of a gravity deposit this layer rests on an erosional unconformity cut into the surface of the older deposits themselves of gravity type one year after the flood no trac

understanding the origin and evolution of water in the moon through lunar sample studies a paradigm shift has recently occurred in our knowledge and understanding of water in the lunar interior this has transpired principally through continued analysis of returned lunar samples using modern analytical instrumentation while these recent studies have undoubtedly measured indigenous water in lunar samples they have also highlighted our current limitations and some future challenges that need to be overcome in order to fully understand the origin distribution and evolution of water in the lunar interior another exciting recent development in the field of lunar science has been the unambiguous detection of water or water ice on the surface of the moon through instruments flown on a number of orbiting spacecraft missions considered together sample based studies and those from orbit strongly suggest that the moon is not an anhydrous planetary body as previously believed new observations and measurements support the possibility of a wet lunar interior and the presence of distinct reservoirs of water on the lunar surface furthermore an approach combining measurements of water abundance in lunar samples and its hydrogen isotopic composition has proved to be of vital importance to fingerprint and elucidate processes and source s involved in giving rise to the lunar water inventory a number of sources are likely to have contributed to the water inventory of the moon ranging from primordial water to meteorite derived water ice through to the water formed during the reaction of solar wind hydrogen with the lunar soil perhaps two of the most striking findings from these recent studies are the revelation that at least some portions of the lunar interior are as water rich as some mid ocean ridge basalt source regions on earth and that the water in the earth and the moon probably share a common origin

examination of sentinel 2a multi spectral instrument msi reflectance anisotropy and the suitability of a general method to normalize msi reflectance to nadir brdf adjusted reflectance abstract the sentinel 2a multi spectral instrument msi acquires multi spectral reflective wavelength observations with directional effects due to surface reflectance anisotropy and changes in the solar and viewing geometry directional effects were examined by considering two ten day periods of sentinel 2a data acquired close to the solar principal and orthogonal planes over approximately 20 10 of southern africa more than 6 6 million january 2016 and 10 6 million april 2016 pairs of reflectance observations sensed 3 or 7 days apart in the forward and backscatter directions in overlapping sentinel 2a orbit swaths were considered the sentinel 2a data were projected into the modis sinusoidal projection but first had to be registered due to a misregistration issue evident in the overlapping orbits the top of atmosphere reflectance data were corrected to surface reflectance using the sen2cor atmospheric correction software only pairs of forward and backward reflectance values that were cloud and snow free unsaturated and had no significant change in their 3 or 7 day separation were considered the maximum observed sentinel 2a view zenith angle was 11 93 greater brdf effects were apparent in the january data acquired close to the solar principal plane than the april data acquired close to the orthogonal plane and at higher view zenith angle for the january data the average difference between the surface reflectance in the forward and backward scatter directions at the sentinel 2a scan edges increased with wavelength from 0 035 blue 0 047 green 0 057 red 0 078 nir to about 0 1 swir these differences may constitute a significant source of noise for certain applications the suitability of a recently published methodology developed to generate landsat nadir brdf adjusted reflectance nbar was examined for sentinel 2a application the methodology uses fixed modis brdf spectral parameters and is attractive because it has little sensitivity to the land cover type condition or surface disturbance and can be derived in a computationally efficient manner globally it was applied to the southern africa sentinel 2a data and shown to reduce sentinel 2a brdf effects the average difference between the reflectance in the forward and backward scatter directions at the sentinel 2a scan edges was smaller in the nbar data than in the corresponding surface reflectance data residual brdf effects in the sentinel 2a nbar data occurred likely because of atmospheric correction and sensor calibration errors and inadequacies in the nbar derivation approach these issues are discussed with recommendations for future research including global and red edge sentinel 2a nbar derivation that were not considered in this study

canopy attributes of desert grassland and transition communities derived from multiangular airborne imagery abstract the surface bidirectional reflectance distribution function brdf contains valuable information on canopy physiognomy for desert grassland and grass shrub transition communities this information may be accessed by inverting a brdf model against sets of observations which encompass important variations in viewing and illumination angles this paper shows that structural canopy attributes can be derived through inversion of the simple geometric model sgm of the brdf developed in this paper it is difficult to sample brdf features from the ground because of the discontinuous nature of the canopies and long intrinsic length scales in remotely sensed spectral measures 10 m a multispectral digital camera was therefore used to derive spatial multiangular reflectance data sets from the air and the sgm was validated against and inverted with these it was also validated using 3 d radiosity simulations driven with maps of field measured plant dimensions the interpretation of the retrieved parameter maps shrub density shrub width and canopy height reveals variations in canopy structure within desert grassland and grassland shrubland transition communities which are clearly related to structural and optical features in high resolution panchromatic and vegetation index images to our knowledge this paper reports on the first attempts to acquire structural canopy attributes of desert landscapes using multiple view angle data at scales less than 1 km the results point to further opportunities to exploit multiangular data from spaceborne sensors such as the multiangle imaging spectroradiometer misr and the compact high resolution imaging spectrometer chris on the nasa terra and european space agency s proba satellites respectively

late quaternary mass movement events in lake el gygytgyn north eastern siberia lake el gygytgyn is situated in a 3ae6 myr old impact crater in north eastern siberia its sedimentary record probably represents the most complete archive of pliocene and quaternary climate change in the terrestrial arctic in order to investigate the influence of gravitational sediment transport on the pelagic sediment record in the lake centre two sediment cores were recovered from the lower western lake slope the cores penetrate a sub recent mass movement deposit that was identified by 3ae5 khz echo sounding in the proximal part of this deposit deformed sediments reflect an initial debris flow characterized by limited sediment mixture above and in front of the debrite a wide massive densite indicates a second stage with a liquefied dense flow the mass movement event led to basal erosion of ca 1 m thick unconsolidated sediments along parts of its flow path the event produced a suspension cloud whose deposition led to the formation of a turbidite the occurrence of the turbidite throughout the lake and the limited erosion at its base mainly suggest deposition by pelagic rain following stokes law very similar radiocarbon dates obtained in the sediments directly beneath and above the turbidite in the central lake confirm this interpretation when applying the depositional model for the late quaternary sediment record of lake el gygytgyn the recovered turbidites allow reconstruction of the frequency and temporal distribution of large mass movement events at the lake slopes in total 28 turbidites and related deposits were identified in two 12ae9 and 16ae6 m long sediment cores from the central lake area covering approximately 300 kyr

ancient geologic events on mars revealed by zircons and apatites from the martian regolith breccia nwa 7034

shallow stratigraphic control on pockmark distribution in north temperate estuaries abstract pockmark fields occur throughout northern north american temperate estuaries despite the absence of extensive thermogenic hydrocarbon deposits typically associated with pockmarks in such settings the origins of the gas and triggering mechanism s responsible for pockmark formation are not obvious nor is it known why pockmarks proliferate in this region but do not occur south of the glacial terminus in eastern north america this paper tests two hypotheses addressing these knowledge gaps 1 the region s unique sea level history provided a terrestrial deposit that sourced the gas responsible for pockmark formation and 2 the region s physiography controls pockmarks distribution this study integrates over 2500 km of high resolution swath bathymetry chirp seismic reflection profiles and vibracore data acquired in three estuarine pockmark fields in the gulf of maine and bay of fundy vibracores sampled a hydric paleosol lacking the organic rich upper horizons indicating that an organic rich terrestrial deposit was eroded prior to pockmark formation this observation suggests that the gas which is presumably responsible for the formation of the pockmarks originated in holocene estuarine sediments loss on ignition 3 5 10 not terrestrial deposits that were subsequently drowned and buried by mud the 7470 pockmarks identified in this study are non randomly clustered pockmark size and distribution relate to holocene sediment thickness r2 0 60 basin morphology and glacial deposits the irregular underlying topography that dictates holocene sediment thickness may ultimately play a more important role in temperate estuarine pockmark distribution than drowned terrestrial deposits these results give insight into the conditions necessary for pockmark formation in nearshore coastal environments

pattern and timing of sediment infill at glacier fed mud lake implications for lateglacial and holocene environments in the monashee mountain region of british columbia canada the holocene sedimentary infill of proglacial mud lake british columbia canada was investigated using 3 5 khz acoustic sub bottom profiling and sediment samples the sediment infill is a mixture of silt and clay and is divided into five stratigraphic units massive silt unit 1 weakly laminated silt with very fine sand beds unit 2 weakly laminated silt with rippled beds of fine sand unit 3 weakly laminated clay with very fine sand laminations unit 4 and silt clay varves unit 5 acoustic reflectors correlate with stratigraphic unit boundaries annual accumulation rates were estimated for six age depth intervals prior to 9 6 kyr cal bp accumulation rates were very high on the order of several centimetres per year early to middle holocene sediment inputs 9 6 3 6 kyr cal bp were variable but low ranging from 0 3 mm yr to 1 2 mm yr the late holocene most recent 3 6 kyr shows annual accumulation rates that generally exceed 2 mm yr surface sediment reveals a mean of 4 3 mm yr over the last 20 years these results are consistent with regional holocene chronologies and long term paraglacial succession 1 maximum sediment and meltwater availability and minimum stabilization by vegetation following fraser deglaciation replaced by 2 less meltwater and sediment availability during the hypsithermal and 3 more stabilized sediment during the early and mid holocene renewal of glacial activity particularly in the late neoglacial has led to increased rates of accumulation in mud lake despite the contrasting geologic setting of mud lake in the omineca belt contemporary sediment yield is consistent with the trend of sediment yield with glacier cover in lakes of the adjacent foreland belt

nanosims analyses of apatite and melt inclusions in the grv 020090 martian meteorite hydrogen isotope evidence for recent past underground hydrothermal activity on mars abstract we measured the hydrogen isotopes and water contents of melt inclusions and apatite that locate far from shock induced melt veins in the martian meteorite grv 020090 using nano scale secondary ion mass spectrometry nanosims the melt inclusions in olivine show hydration profiles with both the water contents and the d values increasing from the cores 2 170 7 ppm and 3386 126 to the rims 5337 200 ppm and 5519 65 the extremely high d values of the melt inclusions relative to a maximum of 4239 81 of apatite that crystallized from the last residual melt convincingly argue that the observed hydration postdated emplacement of the parent magma of grv 020090 this is also a robust line of evidence for past presence of liquid water on mars diffusion simulation of the hydration profiles of both water contents and d values constrains the duration of liquid water up to 130 000 250 000 years at 0 c or 700 1 500 years at 40 c all analyses of the melt inclusions including the hydration profiles show a logarithmic correlation between the water contents and the d values plotting within a two endmember mixing area the extremely d enriched endmember represents martian underground water with a d value of 6034 72 2 this is the highest d value reported in martian meteorites and it is consistent with the recent analyses of martian soils by the curiosity rover leshin et al 2013 suggestive of more water escaped from mars than previous estimates the analyses of apatite show a distinct positive correlation between the water contents 0 10 0 58 wt and the d values 737 4239 which can be explained by assimilation of d rich martian crustal materials and enhancement of water via fractional crystallization the observed correlation suggests that the water contents of martian mantle reservoirs might have been overestimated from d enriched apatite in previous studies our estimation based on the least contaminated apatite grains from grv 020090 turned out a low water content of the primordial parent magma 380 750 ppm which was likely derived from a relatively dry martian mantle reservoir of grv 020090 38 75 ppm h2o

lake sediments and holocene seismic hazard assessment within the st lawrence valley quebec seismoacoustic profiling of 34 lacustrine basins within the st lawrence valley in southern quebec shows the presence of faulting convolution diapirs and gravitational slumping beneath within and at the surface of the holocene deep water sediment zone in small deep lakes in the highlands of the charlevoix tadoussac region a thin 2 6 m holocene organic sedimentary unit which directly overlies over a seismo opaque substratum exhibits considerable deformation these subaquatic sediment disruptions are exclusively restricted to lakes located within a radius of about 100 km of the well known charlevoix seismic zone according to the present seismicity of the region and the spatial distribution of the slump frequency the minimal triggering threshold for earthquakes was found to be as low as 0 17 g these results indicate that the charlevoix seismic zone has occupied the same area throughout at least the holocene and it appears that no major seismic shock has occurred over the past several thousand years outside of the zone

impacts of post glacial lake drainage events and revised chronology of the champlain sea episode 13 9 ka abstract lithologic chirp compressed high intensity radar pulse sonar paleomagnetic stable isotopic and micropaleontological analyses of sediment cores from lake champlain new york vermont were used to determine the age of the post glacial champlain sea marine episode the timing of salinity changes and their relationship to freshwater discharge from mid continent glacial lakes calibrated radiocarbon ages on plant material provide an improved post glacial chronology overcoming problems from shell ages caused by carbon reservoir effects up to 1500 yr the final drainage of glacial lake vermont and the inception of marine conditions occurred 13 1 12 8 ka kiloannum calendar years and a sharp decrease in champlain sea salinity from 25 to 7 8 psu practical salinity units occurred approximately 11 4 11 2 ka reduced salinity was most likely caused by rapid freshwater inflow eastward from glacial lake algonquin into the champlain basin the timing of inferred freshwater event coincides with the widespread climatic cooling called the preboreal oscillation

laminated sediments in glacimarine environments diagnostic criteria for their interpretation abstract fine grained laminated deposits are often reported from contemporary and ancient glacimarine sedimentary sequences laminated glacimarine sediments form by a variety of processes including suspension settling from turbid overflow plumes turbidity current deposition and contour current activity subglacial deformation of pre existing sediments may also produce laminated deposits in the form of glacitectonite and deformation till the development of diagnostic criteria for genetic discrimination of laminated glacimarine sediments is important both for their correct interpretation in sedimentary sequences and also for the accurate reconstruction of former glacier extent and geometry as laminated sediments may form in subglacial ice proximal and ice distal environments this paper reviews the processes by which laminated glacimarine sediments form and their resulting sedimentology the aim is to provide a synthesis of diagnostic sedimentological criteria for laminated glacimarine deposits that will assist in the interpretation of such sediments in the geological record laminated sediments are genetically differentiated on the basis of sedimentary structures bedding contacts stratigraphic relationships and macrofaunal content bioturbation these attributes also facilitate discrimination between glacimarine and glacilacustrine rhythmites the paper concludes by discussing the glaciological significance of laminated glacimarine sediments in terms of glacier hydrology reconstructions of former ice dynamics and basal thermal regime