readjustment of glacial radiocarbon chronologies by self consistent three dimensional ocean circulation modeling a critical problem in radiocarbon dating is the spatial and temporal variability of marine 14c reservoir ages this is particularly true for the time scale beyond the tree ring calibration range here we propose a method to assess the evolution of marine reservoir ages during the last deglaciation by numerical modeling we apply a self consistent iteration scheme in which existing radiocarbon chronologies can be readjusted by transient three dimensional simulations of marine and atmospheric 14c to estimate the uncertainties regarding the ocean ventilation during the last deglaciation we consider various ocean overturning scenarios which are based on different climatic background states an example readjusting 14c data from the caribbean points to marine reservoir ages varying between 200 and 900 a during the last deglaciation correspondingly the readjustment leads to enhanced variability of atmospheric 14c by 30 and increases the mysterious drop of atmospheric 14c between 17 5 and 14 5 cal ka bp by about 20

marine derived 14c calibration and activity record for the past 50 000 years updated from the cariaco basin abstract an expanded cariaco basin 14c chronology is tied to 230th dated hulu cave speleothem records in order to provide detailed marine based 14c calibration for the past 50 000 years the revised high resolution cariaco 14c calibration record agrees well with data from 230th dated fossil corals back to 33 ka with continued agreement despite increased scatter back to 50 ka suggesting that the record provides accurate calibration back to the limits of radiocarbon dating the calibration data document highly elevated 14c during the glacial period carbon cycle box model simulations show that the majority of observed 14c change can be explained by increased 14c production however from 45 to 15 ka 14c remains anomalously high indicating that the distribution of radiocarbon between surface and deep ocean reservoirs was different than it is today additional observations of the magnitude spatial extent and timing of deep ocean 14c shifts are critical for a complete understanding of observed glacial 14c variability

synchronous and proportional deglacial changes in atlantic meridional overturning and northeast brazilian precipitation changes in heat transport associated with fluctuations in the strength of the atlantic meridional overturning circulation amoc are widely considered to affect the position of the intertropical convergence zone itcz but the temporal immediacy of this teleconnection has to date not been resolved based on a high resolution marine sediment sequence over the last deglaciation we provide evidence for a synchronous and near linear link between changes in the atlantic interhemispheric sea surface temperature difference and continental precipitation over northeast brazil the tight coupling between amoc strength sea surface temperature difference and precipitation changes over northeast brazil unambiguously points to a rapid and proportional adjustment of the itcz location to past changes in the atlantic meridional heat transport

the role of hydrothermal processes in the granite hosted zr y ree deposit at strange lake quebec labrador evidence from fluid inclusions abstract the strange lake zr y ree nb and be deposit is hosted by a small high level late proterozoic peralkaline granite stock that intruded into high grade metamorphic gneisses on the quebec labrador border the stock is extensively altered early alteration is manifested by the replacement of arfvedsonite with aegirine later alteration involved ca na exchange zr ti y rees nb and be are concentrated in ca bearing minerals that together with quartz commonly pseudomorph na bearing minerals fluid inclusions in pseudomorphs comprise several distinct types high salinity 13 to 24 wt nacl eq ca rich aqueous inclusions that homogenize to liquid between 135 and 195 c mixed aqueousmethane inclusions methane inclusions and solid bearing inclusions aqueous methane inclusions represent heterogeneous entrapment of immiscible high salinity aqueous liquid and methane bastnasite tentatively identified by sem analysis occurs as a daughter mineral other daughter or trapped minerals include a y hree bearing mineral possibly gagarinite and hematite galena sphalerite fluorite pyrochlore kutnahorite and griceite the first three inclusion types also occur in quartz in pegmatites and veins together with lower temperature lower salinity na dominated aqueous inclusions the entrapment temperature inferred for the aqueous inclusions from microthermometry and the na k ca geothermometer range from 155 to 195 c for the higher salinity inclusions and 100 to 165 c for the low salinity inclusions a model is proposed in which the intrusion of a peralkaline granite to high crustal levels initiated a ground formational water dominated hydrothermal system in adjacent gabbroic calc silicate and graphitic gneisses reaction of the high salinity ca rich liquid with the graphitic gneisses led to the production of an immiscible methane gas subsequent interaction of this liquid with the granite led to extensive replacement of sodic minerals by calcium analogues at temperatures of less than 200 c some time after the onset of ca metasomatism the high salinity liquid mixed with a ca poor low salinity low temperature liquid that had leached f and rare metals from the granite yttrium and ree mineral deposition occurred as a result of the decreased ligand concentration that accompanied fluorite deposition during mixing of the ca rich and ca poor aqueous liquids

preliminary petrogenetic grids for sodium and calcium zirconosilicate minerals in felsic peralkaline rocks the sio 2 na 2 zro 3 and sio 2 cazro 3 pseudobinary systems

gravity wave and equatorial wave morphology of the stratosphere derived from long term rocket soundings fluctuations in vertical profiles of atmospheric temperature and horizontal wind in the 20 60 km altitude range have been isolated from meteorological rocket measurements during 1977 87 at 15 widely separated sites the seasonal geographical and vertical variability of the variance of horizontal velocities u 2 2 and relative temperature perturbations t 2 were studied the bulk of the variance of both quantities in the 2 10 km and 2 20 km vertical wavelength bands was associated with gravity wave motions although in depth study of the wave polarization shows that planetary scale equatorial wave modes contribute to the variance at equatorial sites annual mean variances varied widely among the 15 stations suggesting appreciable geographical variability in stratospheric wave activity

glacial to deglacial changes in north atlantic meltwater advection and deep water formation centennial to millennial scale 14c records from the azores plateau abstract the last deglacial was marked by tremendous changes in ocean temperature and circulation as well as atmospheric co2 and 14c we employed the 14c plateau tuning technique to a centennial scale planktic 14c record of core md08 3180 retrieved s w of the azores islands at 3060 m water depth to establish both a new standard of absolute age control and a record of past 14c reservoir ages of ocean surface waters both 18o minima of g bulloides and high planktic reservoir ages of 1600 to 2170 yr suggest two major melt water incursions that reached from the labrador sea up to the subtropics over heinrich stadial 1 hs 1 in parallel we established a record of apparent benthic ventilation ages that add the planktic 14c reservoir ages together with the benthic planktic 14c age difference at the site and time of deposition a sum finally adjusted to past changes in atmospheric 14c that occurred since the time of deep water formation near the azores apparent deep water ages of the last glacial maximum were as low as 340 740 yr which suggests a lateral advection of young north atlantic deep waters nadw from subpolar regions south of iceland in harmony with recent model simulation and in contrast to a widely assumed major shoaling of glacial deep water formation during hs 1 local benthic ventilation ages increased up to 2200 2550 yr thus suggest an incursion of old southern source deep waters an unstable regime that was interrupted by brief pulses of nadw incursion near 16 15 6 cal ka and most salient near 14 9 14 7 ka

lidar observations of atmospheric dynamics in the troposphere and lower stratosphere over arecibo a periodic wave structure with a vertical wave length typically 2 km between 14 and 23 km altitudes has been identified in lidar measurements of relative density profiles at 589 nm that were made by the university of illinois group during the march april aida 1989 campaign effort the equivalent temperature fluctuations are several degrees in magnitude also seen are stratified aerosol layers at altitudes near 25 km with a vertical extent of 1 km both of these phenomena show a downward phase speed between 1 and 3 cm s 1 the lower periodic structure is believed to be the same phenomenon seen previously in 430 mhz measurements of winds obtained at arecibo observatory the source of this structure remains uncertain cornish and larsen 1989 and sato and woodman 1982a considered this structure to be a quasi inertial long period wave hines 1989 proposed instead the identification of this structure with a stationary wave system generated by orographic waves created through the interaction of the subtropical trade winds with the mountainous terrain of puerto rico the higher altitude feature seen in the aida lidar observations is believed to be an aerosol layer with a scattering ratio of about 1 15 an alternative explanation is clear air turbulence but the signature of the 10 k fluctuation deduced from the lidar observations was not found in the san juan balloon measurement of the temperature profile for the lower stratosphere

observations of high frequency temporal gravity wave spectra in the middle upper stratosphere there is a paucity of high frequency temporal gravity wave spectra in the middle upper stratosphere 30 40 km as most instruments that are capable of accessing this region do not have the capability to make measurements for any extended period of time the spectral analysis of density fluctuations obtained with the purple crow rayleigh scatter lidar has shown that middle upper stratospheric temporal spectra follow the expected 1 5 to 2 0 power law relationship for frequencies less than 1 10 3 s 1 at frequencies greater than 1 10 3 s 1 the shape of the temporal spectrum is much more variable with strong quasi monochromatic features appearing intermittently on certain nights these higher frequency features have been attributed to nonlinear wave interactions and suggest that estimates of gravity wave activity in the middle upper stratosphere may be larger and much more variable than previously assumed this variability also suggests that middle upper stratospheric energy dissipation and eddy diffusion values may be much larger and more variable than previously assumed current parameterizations of subgrid dynamical processes in general circulation models that resolve this region may need to be reexamined in this light

the probable occurrence of interstitial al in hydrous f bearing and f free aluminosilicate melts experiments carried out on the system sio2 naalsi3o8 kalsi3o8 qz ab or at 1 kbar in the presence of h2o and f show that the quartz alkali feldspar field boundary is progressively displaced towards the feldspar join as f contents increase from 0 to 4 wt f increasing p h 2 o in the absence of f has already been shown to have a similar effect tuttle and bowen 1958 luth jahns and tuttle 1964 the increased size of the quartz field in the f bearing system compared to the hydrous system is believed to be caused by progressive removal of al from the tetrahedral network of the melt by complexing with f the residual network in the melt is thus enriched in si and this stabilizes precipitation of quartz rather than feldspar for certain bulk compositions the common presence of quench cryolite na3alf6 in certain experiments carried out with 4 wt f supports this interpretation and indicates that some al in the melt may be present in six fold coordination with f the effect of h2o in the absence of f may be similar with al being progressively removed from four fold coordination as more h2o is dissolved in the melt although a proportion of al in hydrous melts may occur in six fold coordination dry melts predominantly contain al in four fold coordination this major difference in al complexing may be one of the main causes for differences in the high pressure phase relations of wet and dry albearing silicate systems

simulation of lidar measurements of gravity waves in the mesosphere lidar measurements of mesospheric gravity wave characteristics are simulated using a simple numerical model simple theory is used to superimpose gravity wave fluctuations upon typical background densities and sodium abundances in the height range 80 100 km which we then assume are perfectly observed by a rayleigh and na lidar respectively these lidar data are then analyzed for their gravity wave content using the standard reduction and analysis methods which are routinely applied to these data sets our goal is to assess whether this analysis of lidar data faithfully recovers the underlying wave field in both quasi monochromatic and spectral wave studies the height range over which na number density can be measured and the shape of the background na profile impose a limit on the gravity wave information which can be extracted from na lidar data the limitations due to background layer shape do not exist for rayleigh lidar measurements the simulations reveal that quasi monochromatic gravity waves with vertical wavelengths larger than approximately 10 km may not be reliably retrieved from na lidar data it is also shown that there are limitations on the accurate extraction of spectral parameters from na lidar data due to the limited vertical extent of the mesospheric na layer

coupling of millennial scale changes in sea surface temperature and precipitation off northeastern brazil with high latitude climate shifts during the last glacial period 1 high resolution records of alkenone derived sea surface temperatures and elemental ti ca ratios from a sediment core retrieved off northeastern brazil 4 s reveal short term climate variability throughout the past 63 000 a large pulses of terrigenous sediment discharge caused by increased precipitation in the brazilian hinterland coincide with heinrich events and the younger dryas period terrigenous input maxima related to heinrich events h6 h2 are characterized by rapid cooling of surface water ranging between 0 5 and 2 c this signature is consistent with a climate model experiment where a reduction of the atlantic meridional overturning circulation amoc and related north atlantic cooling causes intensification of ne trade winds and a southward movement of the intertropical convergence zone resulting in enhanced precipitation off northeastern brazil during deglaciation the surface temperature evolution at the core site predominantly followed the antarctic warming trend including a cooling prior to the younger dryas period an abrupt temperature rise preceding the onset of the bolling allerod transition agrees with model experiments suggesting a southern hemisphere origin for the abrupt resumption of the amoc during deglaciation caused by southern ocean warming and associated with northward flow anomalies of the south atlantic western boundary current

statistical study of atmospheric gravity waves in the mesopause region observed by a lidar chain in eastern china atmospheric gravity wave activities in the mesopause region have been observed and statistically investigated with a sodium lidar chain in eastern china in total there were 471 gravity waves identified from over 5400h of observations at hainan 19 99 degrees n 110 34 degrees e hefei 31 87 degrees n 117 23 degrees e and beijing 40 47 degrees n 115 97 degrees e these waves typically had vertical wavelengths of z 2 4km observed periods of t ob 1 4h amplitude growth factors of 0 025 similar to 0 05km 1 and wave amplitudes of ae 90km 1 5 6 strong systematic parameter relationships were found and they agree with the predictions of diffusive filtering theory statistical results show that the seasonal variability of gravity wave activity had a summer maximum and winter minimum characteristics in the mesopause region over eastern china a qualitative interpretation is proposed regarding the seasonal and geographic variability observed by the lidar chain based on analysis of source properties and influences from background wind which vary by season

rapid palaeoceanographic changes in the benguela upwelling system for the last 160 000 years as indicated by abundances of planktonic foraminifera abstract two sediment cores retrieved from the continental slope in the benguela upwelling system geob 1706 19 33 7 s 11 10 5 e and geob 1711 23 18 9 s 12 22 6 e reveal striking variations in planktonic foraminiferal abundances during the last 160 000 years these fluctuations are investigated to assess changes in the intensity and position of the upwelling centres off namibia four species make up over 95 of the variation within the core and enable the record to be divided into episodes characterized by particular planktonic foraminiferal assemblages the fossil assemblages have meaningful ecological significance when compared to those of the modern day and the relationship to their environment the cold water planktonic foraminifer neogloboquadrina pachyderma sinistral n pachyderma s dominates the modern day coastal upwelling centres and neogloboquadrina pachyderma dextral and globigerina bulloides characterize the fringes of the upwelling cells globorotalia inflata is representative of the offshore boundary between newly upwelled waters and the transitional reduced nutrient levels of the subtropical waters in the fossil record episodes of high n pachyderma s abundances are interpreted as evidence of increased upwelling intensity and the associated increase in nutrients the n pachyderma s record suggests temporal shifts in the intensity of upwelling and corresponding trophic domains that do not follow the typical glacial interglacial pattern periods of high n pachyderma s abundance describe rapid discrete events dominating isotope stages 3 and 2 the timing of these events correlates to the temporal shifts of the angola benguela front jansen et al 1997 situated to the north of the walvis ridge absence of high abundances of n pachyderma s from the continental slope of the southern cape basin indicates that southern ocean surface water advection has not exerted a major influence on the benguela current system the coincidence of increased upwelling intensity with the movement of the angola benguela front can be interpreted mainly by changes in strength and zonality of the trade wind system

rayleigh lidar measurements of the temporal frequency and vertical wavenumber spectra in the mesosphere over the rocky mountain region temporal and spatial spectral analysis techniques were applied to lidar data collected over a period of 18 months above the rocky mountain region at an altitude range from 45 to 70 km by a rayleigh lidar system located in logan utah 41 7 n 111 8 w examination of the averaged temporal frequency f and vertical wavenumber f m spectra showed spectral slope values of 1 49 0 03 and 2 3 0 1 respectively the observed slope for the overall averaged f m spectrum is considerably more positive than the value of 3 predicted by the linear instability theory but close to the value of 2 that is predicted by the scale independent diffusive filtering theory using the measured f slope parameter however examination of the monthly averaged f m spectra for the transition from winter to summer showed the spectra became flatter suggesting that doppler shift effects caused by the seasonal change in the magnitude and direction of the background wind field are significant the characteristic vertical wavelength was found to be 12 km for the altitude region of 45 70 km comparison of this value with the characteristic wavelengths from other lidar observations at lower and higher altitude ranges showed an overall increase of with height the observed enhancement of the f m spectral magnitude in winter is believed to be caused in part by the low frequency wave activity observed in the temperature profiles

chronologie rb sr et k ar du granite peralcalin du lac brisson labrador central nouveau quebec a rb sr whole rock isochron gives an age of 1189 32 ma for the peralkaline granite of lake brisson k ar data on amphiboles yield an age of 1163 21 ma which further confirms our dating such an age allows the corresponding magmatism to be attributed to the late stage of the gardar anorogenic province which till now has been unknown in labrador

an investigation of intrinsic gravity wave signatures using coordinated lidar and nightglow image measurements simultaneous observations of gravity waves using an na wind temperature lidar and a multi wavelength all sky nightglow imager were obtained for the first time during the aloha 93 campaign a novel investigation of intrinsic wave parameters has been made by combining measurements of the horizontal wave components imaged in four nightglow emissions height range 80 100 km with na lidar soundings of the horizontal wind field and temperature profiles over the same height interval on october 19 both instruments registered marked monochromatic wave motions the intrinsic periods of several of these waves have been determined and were found to vary considerably with altitude often resulting in a significant increase over their observed wave periods it is shown that these two instrumental techniques generally sampled different regions of the gravity wave spectrum the lidar exhibiting most sensitivity to short vertical wavelength waves less than about 10 km while the imager was most responsive to larger vertical wavelength waves this study illustrates the significant advantages of combining wind temperature lidar and multi wavelength image observations for intrinsic gravity wave measurements

an atlantic pacific ventilation seesaw across the last deglaciation it has been proposed that the rapid rise of atmospheric co2 across the last deglaciation was driven by the release of carbon from an extremely radiocarbon depleted abyssal ocean reservoir that was vented to the atmosphere primarily via the deep and intermediate overturning loops in the southern ocean while some radiocarbon observations from the intermediate ocean appear to confirm this hypothesis others appear to refute it here we use radiocarbon measurements in paired benthic and planktonic foraminifera to reconstruct the benthic planktonic 14c age offset i e ventilation age of intermediate waters in the western equatorial atlantic our results show clear increases in local radiocarbon based ventilation ages during heinrich stadial 1 hs1 and the younger dryas yd these are found to coincide with opposite changes of similar magnitude observed in the pacific demonstrating a seesaw in the ventilation of the intermediate atlantic and pacific oceans that numerical model simulations of north atlantic overturning collapse indicate was primarily driven by north pacific overturning we propose that this atlantic pacific ventilation seesaw would have combined with a previously identified north atlantic southern ocean ventilation seesaw to enhance ocean atmosphere co2 exchange during a collapse of the north atlantic deep overturning limb whereas previous work has emphasized a more passive role for intermediate waters in deglacial climate change merely conveying changes originating in the southern ocean we suggest instead that the intermediate water seesaw played a more active role via relatively subtle but globally coordinated changes in ocean dynamics that may have further influenced ocean atmosphere carbon exchange

high resolution temperature profiles measured with stratospheric balloons near the andes mountains a spectral analysis of two balloon soundings of temperature performed in the troposphere and lower stratosphere over the andes mountains in argentina with a vertical resolution of 10 m has been performed the first and second soundings launched at the same location were performed during unusually calm and disturbed atmospheric conditions respectively considerable deviations from the 3 value predicted for the spectral slopes in the power law range by current saturation theories are found these departures are reduced if the data resolution at disposal is diminished thereby eliminating the highest wavelength harmonics slopes do not clearly steepen with increasing height as suggested by other authors and topography seems to be responsible for this fact at low altitudes the spectral amplitude increase with height detected from recent lidar data is corroborated only in the sounding with calm atmospheric conditions spectra are found to scale with the buoyancy frequency not as simply as suggested by the saturation models

lidar observations of gravity waves and their spectra near the mesopause and stratopause at arecibo abstract the uiuc cedar rayleigh na lidar was operated for approximately 160 h on 30 nights in january march and april 1989 at the arecibo observatory 18 n 67 w as part of the aida act 89 campaign during this period 38 quasi monochromatic gravity waves were observed in the stratopause region 25 55 km and 62 waves were observed in the mesopause region 80 105 km the event rates in both regions are approximately half those observed at the midlatitude site of urbana the characteristics of the waves in both regions are similar measured vertical wavelengths range from 1 1 to 17 km vertical phase velocities from 6 to 270 cm s 1 observed periods from 5 min to 65 h and amplitudes relative atmospheric density variations 0 4 to 17 the wave amplitudes in the stratopause region are on average half the values for waves in the mesopause region with similar periods and vertical wavelengths vertical wavenumber spectra of density perturbations in both regions exhibit power law dependencies with slo

shelf break upwelling driven by brazil current cyclonic meanders analysis of hydrographic data and results of numerical modeling show the occurrence of upwelling associated with the cyclonic meanders of the brazil current in the region known as the southeast brazil bight or santos bight the temperature and salinity distributions collected during summer and winter confirm the idea that meander induced shelf break upwelling plays an important role in the pumping of south atlantic central water from the slope region onto the continental shelf

atlantic ocean circulation during the younger dryas insights from a new cd ca record from the western subtropical south atlantic author posting american geophysical union 2003 this article is posted here by permission of american geophysical union for personal use not for redistribution the definitive version was published in paleoceanography 18 2003 1086 doi 10 1029 2003pa000888

comment on the role of hydrothermal processes in the granite hosted zr y ree deposit at strange lake quebec labrador evidence from fluid inclusions by s salvi and a e williams jones

rayleigh lidar observations of quasi sinusoidal waves in the tropical middle atmosphere 1 rayleigh lidar observations of temperature for 2 7 hours on 38 nights during the period of 18 january 5 march 1999 and for 3 hours on 29 nights during 29 february 2 april 2000 in the altitude region of 27 60 km over gadanki 13 5 n 85 e clearly show the dominance of the quasi sinusoidal waves of periods in the range of 6 13 hours in temperature in the tropical middle atmosphere during 1999 the vertical wavelength of these waves ranges from 7 1 to 17 km with a mean value of 12 0 2 4 km while during 2000 it ranges from 5 5 to 17 km with a mean value of 11 4 3 5 km the wave periods estimated from the observations during 1999 are generally greater than the observation period on each night and are estimated to be in the range of 6 5 13 1 hours with an average period of 9 7 1 8 hours which is significantly smaller than the inertial period of 53 hours the amplitudes of these waves are in the range of 1 to 8 k such sinusoidal wave modes are clearly discernible in the temperature profiles for 50 nights of observation another striking feature is that the quasi sinusoidal structure is clearly observed in the equivalent day analysis also indicating only small day to day variability in phase a property that is characteristic of atmospheric tides

simulating the ice thickness distribution in a coupled climate model climate simulations in a global coupled model are investigated using a dynamic thermodynamic sea ice and snow model with sophisticated thermodynamics and a subgrid scale parameterization for multiple ice thicknesses in addition to the sea ice component the model includes a full primitive equation ocean and a simple energy moisture balance atmosphere we introduce a formulation of the ice thickness distribution that is lagrangian in thickness space the method is designed to use fewer thickness categories because it adjusts to place resolution where it is needed most and it is free of diffusive effects that tend to smooth eulerian distributions experiments demonstrate that the model does reasonably well in simulating the mean arctic climate we find the climate of the arctic and northern north atlantic is sensitive to resolving the ice thickness distribution when comparing the model results to a simulation with a two level sea ice model the ice thickness distribution causes ice export through fram strait to be more variable and more strongly linked to meridional overturning in the north atlantic ocean the lagrangian formulation of the ice thickness distribution allows for the inclusion of a vertical temperature profile with relative ease compared to an eulerian method we find ice growth rates and ocean surface salinity differ in our model with a well resolved vertical temperature profile in the ice and snow and an explicit brine pocket parameterization compared to a simulation with semtner zero layer thermodynamics although these differences are important for the climate of the arctic the effects of an ice thickness distribution are more dramatic and extend into the northern north atlantic sensitivity experiments indicate that five ice thickness categories with 50 cm vertical temperature resolution capture the effects of the ice thickness distribution on the heat and freshwater exchange across the surface in the presence of sea ice in these simulations

seasonal associations of phytoplankton and planktic foraminifera in an upwelling region and their contribution to the seafloor abstract seasonal occurrences of both phytoplankton and zooplankton are closely associated with upwelling and stabilization in waters overlying the san pedro basin this region is situated within the southern california bight and is affected by variations in the general southward flowing california current and variable intrusion of oceanic waters increased northerly wind stress in spring and early summer results in upwelling of deeper nutrient rich waters into the photic zone a seven month time series sediment trap experiment revealed clear patterns in seasonal succession of both phytoplankton and planktic foraminifera several distinct high and low flux periods occurred over the study period some of which can be related to rapid changes in the hydrographic environment caused by upwelling and subsequent surface water stratification factor analysis of relative abundances of combined phytoplankton and foraminiferal taxa defines seven assemblages reflecting seven stages of production which range in duration from two to five weeks factor scores describe phytoplankton and foraminiferal taxa indicative of specific production stages periods of high flux of the more abundant diatoms and planktic foraminifera also illustrate preferred production stages and compare well with percentage based results a comparison of the sediment trap assemblage with local sediment from an oxygenated portion of the basin suggests that long term phytoplankton accumulation in this region is dominated by taxa associated with winter bloom and post upwelling bloom production implying that brief but massive episodic events overwhelm and dominate the annually averaged diatom species assemblage found in the sediments foraminifera however are modified by dissolution to the extent that the high production periods of late spring and during upwelling are poorly represented rather species indicative of early spring and post upwelling conditions dominate the planktic foraminiferal sedimentary assemblage

gravity waves in the upper mesosphere over antarctica lidar observations at the south pole and syowa lidar observations of the mesospheric na layer were made at the south pole 90 s and syowa 69 s during the winters of 1990 and 1985 respectively these observations are used to characterize the gravity wave activity in the upper mesosphere at both sites strong wave activity is observed throughout the winter at both the south pole and syowa and shows remarkable similarity with observations from several midlatitude and low latitude sites the quasi monochromatic gravity waves exhibit the same general relationships between their wavelengths observed periods and amplitudes as observed at lower latitudes the average growth length of these waves is approximately 26 km indicating that the wave field at both antarctic sites is strongly influenced by dissipation and saturation processes the spectra and variances of the density perturbations associated with quasi random wave field at the south pole are reported the vertical wavenumber and temporal frequency spectra follow power law shapes the mean index of the vertical wavenumber spectrum is 2 4 and the mean characteristic wavelength is 14 km the mean index of the temporal frequency spectrum is 1 7 the mean density variance at the south pole is 5 7 2 and is similar in magnitude to that observed at a variety of lower latitude sites with no tropospheric convection during the polar night and little orographic forcing over the relatively featureless antarctic plateau these observations suggest that nonlinear processes rather than the source characteristics primarily determine the characteristics of the gravity wave field in the upper mesosphere these observations show two other distinct features the mean na layer over antarctica is significantly lower and broader centroid height 90 km and rms width 4 8 km than at lower latitudes reflecting the stronger downwelling and warmer winter temperatures in the mesopause region at high latitudes strong coherent oscillations were observed in the bottomside density contours of the na layer with periods close to the inertial period these oscillations were also observed in oh airglow measurements and appear to be associate with planetary scale waves

increased upwelling off portugal during the last glaciation diatom evidence abstract quantitative studies have been carried out on opaline microfossils and diatom assemblage composition and preservation in two latest quarternary 100 ka to p d cores from the continental slope of portugal the sites are located in an area of modern summer coastal upwelling created by northerly trade winds the spatial patterns and intensity of this upwelling system are accurately recorded by the diatom abundances and taxonomic composition in the surface sediments the diatom record in these sequences indicates that coastal upwelling intensity was similar to present day during late holocene interglacial stage 3 and late stage 5 higher during stage 2 and lower in the early holocene paleoproductivity estimates are consistent with the diatom accumulation rates from stage 3 to the recent this indicates that both the diatom and the organic carbon content of the sediments mainly reflect the biological productivity in the euphotic zone

noctilucent clouds and wave dynamics observations at sondrestrom greenland rayleigh lidar measurements of the arctic summer stratosphere and mesosphere have been conducted routinely since 1994 at the sondrestrom atmospheric research facility near kangerlussuaq greenland 67 0n 50 9w between 1994 and 1996 seventeen separate events of noctilucent clouds nlcs as well as corresponding stratospheric wave structure have been observed we present in this study two main results 1 the occurrence of persistent quasi monochromatic wave structure in the stratosphere having observed vertical wavelengths of 8 to 12 km and observed temporal periods of approximately 2 3 hours and 2 evidence that the strength of such lower altitude waves may be associated with the overall strength of the observed nlc volume backscatter coefficient

enhanced δ13c and δ18o differences between the south atlantic and south pacific during the last glaciation the deep gateway hypothesis enhanced vertical gradients in benthic foraminiferal 13c and 18o in the atlantic and pacific during the last glaciation have revealed that ocean overturning circulation was characterized by shoaling of north atlantic sourced interior waters nonetheless our understanding of the specific mechanisms driving these glacial isotope patterns remains incomplete here we compare high resolution depth transects of cibicidoides spp 13c and 18o from the southwest pacific and the southwest atlantic to examine relative changes in northern and southern sourced deep waters during the last glacial maximum lgm and deglaciation during the lgm our transects show that water mass properties and boundaries in the south atlantic and pacific were different from one another the atlantic between 1 0 and 2 5 km was more than 1 enriched in 13c relative to the pacific and remained more enriched through the deglaciation during the lgm atlantic 18o was 0 5 more enriched than the pacific particularly below 2 5 km this compositional difference between the deep portions of the basins implies independent deep water sources during the glaciation we attribute these changes to a deep gateway effect whereby northern sourced waters shallower than the drake passage sill were unable to flow southward into the southern ocean because a net meridional geostrophic transport cannot be supported in the absence of a net east west circumpolar pressure gradient above the sill depth we surmise that through the lgm and early deglaciation shoaled northern sourced waters were unable to escape the atlantic and contribute to deep water formation in the southern ocean

radiocarbon evidence for alternating northern and southern sources of ventilation of the deep atlantic carbon pool during the last deglaciation recent theories for glacial interglacial climate transitions call on millennial climate perturbations that purged the deep sea of sequestered carbon dioxide via a bipolar ventilation seesaw however the viability of this hypothesis has been contested and robust evidence in its support is lacking here we present a record of north atlantic deep water radiocarbon ventilation which we compare with similar data from the southern ocean a striking coherence in ventilation changes is found with extremely high ventilation ages prevailing across the deep atlantic during the last glacial period the data also reveal two reversals in the ventilation gradient between the deep north atlantic and southern ocean during heinrich stadial 1 and the younger dryas these coincided with periods of sustained atmospheric co2 rise and appear to have been driven by enhanced ocean atmosphere exchange primarily in the southern ocean these results confirm the operation of a bipolar ventilation seesaw during deglaciation and underline the contribution of abrupt regional climate anomalies to longer term global climate transitions

the amphiboles of the ree rich a type peralkaline strange lake pluton fingerprints of magma evolution abstract major and trace element compositions of amphibole in igneous environments commonly reflect evolving magma compositions in this study we use the amphibole group minerals from the strange lake ree enriched peralkaline granitic pluton to gain insights into the evolution of the magma this 1240 ma old pluton consists of two main intrusive facies an early hypersolvus granite which occurs as separate northern and southern intrusions and a more evolved transsolvus granite in the hypersolvus granite the amphibole is a late interstitial phase whereas in the transsolvus granite it is present as phenocrysts the amphibole compositions vary from calcic sodic ferro ferri katophorite in the southern hypersolvus granite to sodic arfvedsonite ferro ferri leakeite in the other more evolved granitic units high na si li and low al and ca concentrations in the amphibole phenocrysts of the transsolvus granite indicate formation from a more evolved magma compared to the hypersolvus granite despite the fact that these crystals formed early we interpret the increasing fe 3 fe 2 ratios in the amphibole of the hypersolvus granite to reflect crystal chemical effects na ca ratio and increasingly oxidizing conditions in the magma whereas in the phenocrysts of the transsolvus granite the increasing ratio was the product of increasing proportions of f and oh in the melt the amphiboles of all the granite units have elevated nb zr hf and ree concentrations compared to the bulk rock suggesting that these elements are compatible in amphibole by contrast the much lower ti concentration was due to saturation of the magma in sodium titanosilicates the amphibole ree concentrations vary greatly among the granite units amphibole of the southern and northern hypersolvus granite contains 0 16 and 0 07 wt ree y on average respectively and in the transsolvus granite the average ree content is only 0 01 wt despite the more evolved nature of its host transsolvus granite we intrepret this compositional difference to be due to the fact that the latter represents phenocrysts which crystallized early whereas the hypersolvus arfvedsonite is a late interstitial phase chondrite normalized ree profiles emphasise the wide range in lree and the narrow range in hree concentrations of the amphiboles the variations in the lree profiles reflect the variable crystallization of primary lree bearing phases including monazite ce pyrochlore group minerals and gagarinite ce prior to or contemporaneous with the amphibole as well as the exsolution of a lree rich fluoride melt the lree are incompatible in the amphibole structure apparent d d 1 owing to their small ionic radius and their compatibility with the amphibole structure hree concentrations were more controlled by partitioning crystal chemical effects than by the concentrations in the corresponding magma large proportions of the bulk hree content up to 70 reside in the amphibole and their later release through hydrothermal replacement helps to explain the extreme and unusual hree enrichment of the strange lake pluton

paired δ18o signals of neogloboquadrina pachyderma s and turborotalita quinqueloba show thermal stratification structure in nordic seas abstract the vertical density gradients in the nordic seas are crucial for the preconditioning of the surface water to thermohaline sinking in winter these gradients can be reconstructed from paired oxygen isotope data in tests of different species of planktonic foraminifera the isotopic signatures of which represent different calcification depths in the water column comparison of 18 o values from foraminiferal tests in plankton hauls sediment traps and nearby core top samples with the calculated 18 o calcite profile of the water column revealed species specific 18 o vital effects and the role of bioturbational admixture of subfossil specimens into the surface sediment on the basis of core top samples obtained along a west east transect across various hydrographic regions of the nordic seas 18 o values of turborotalita quinqueloba document apparent calcification depths within the pycnocline at 25 75 m water depth the isotopic signatures of neogloboquadrina pachyderma s reflect water masses near and well below the pycnocline between 70 and 250 m off norway where the atlantic inflow leads to thermal stratification here temperatures in the calcification depth of n pachyderma s differ from sea surface temperature by approximately 2 5 c in contrast n pachyderma s calcifies very close to the sea surface 20 50 m in the arctic domain of the western nordic seas however further west n pachyderma s prefers somewhat deeper more saline water at 70 130 m well below the halocline that confines the low saline east greenland current this implies that the 18 o values of n pachyderma s do not fully reflect the freshwater proportion in surface water and that any reconstruction of past meltwater plumes based on 18 o is too conservative because it overestimates sea surface salinity minimum 18 o differences n pachyderma s and t quinqueloba may serve as proxy for sea regions with dominant haline and absent thermal stratification whereas thermal stratification leads to 18 o differences of 0 4 to 1 5

a coordinated study of 1 h mesoscale gravity waves propagating from logan to boulder with crrl na doppler lidars and temperature mapper we present the first coordinated study using two lidars at two separate locations to characterize a 1 h mesoscale gravity wave event in the mesopause region the simultaneous observations were made with the student training and atmospheric research star na doppler lidar at boulder co and the utah state university na doppler lidar and temperature mapper at logan ut on 27 november 2013 the high precision possessed by the star lidar enabled these waves to be detected in vertical wind the mean wave amplitudes are 0 44 m s in vertical wind and 1 in relative temperature at altitudes of 82 107 km those in the zonal and meridional winds are 6 1 and 5 2 m s averaged from 84 to 99 km the horizontal and vertical wavelengths inferred from the mapper and lidars are 219 4 and 16 0 0 3 km respectively the intrinsic period is 1 3 h for the airglow layer doppler shifted by a mean wind of 17 m s the wave packet propagates from logan to boulder with an azimuth angle of 135 clockwise from north and an elevation angle of 3 from the horizon the observed phase difference between the two locations can be explained by the traveling time of the 1 h wave from logan to boulder which is about 2 4 h the wave polarization relations are examined through the simultaneous quantifications of the three wind components and temperature this study has developed a systematic methodology for fully characterizing mesoscale gravity waves inspecting their intrinsic properties and validating the derivation of horizontal wave structures by applying multiple instruments from coordinated stations

alkali zirconosilicates in peralkaline rocks based on the crystal chemistry of alkali zirconosilicates azs it is argued that zr in silicate melts is a network modifier rather than a complex former with the aid of silicate melt theory the late crystallization of azs in peralkaline melts can be explained the high ks ns and high q calculated in some norms of peralkaline rocks but not expected from the modes is the result of calculating zrsio4 rather than k na 2zrsio5 xsio2

glacial north atlantic sea surface conditions reconstructed by glamap 2000 the response of the tropical ocean to global climate change and the extent of sea ice in the glacial nordic seas belong to the great controversies in paleoclimatology our new reconstruction of peak glacial sea surface temperatures ssts in the atlantic is based on census counts of planktic foraminifera using the maximum similarity technique version 28 simmax 28 modern analog technique with 947 modern analog samples and 119 well dated sediment cores our study compares two slightly different scenarios of the last glacial maximum lgm the environmental processes of the ice age land oceans glaciers epilog and glacial atlantic ocean mapping glamap 2000 time slices the comparison shows that the maximum lgm cooling in the southern hemisphere slightly preceeded that in the north in both time slices sea ice was restricted to the north western margin of the nordic seas during glacial northern summer while the central and eastern parts were ice free during northern glacial winter sea ice advanced to the south of iceland and faeroe in the central northern north atlantic an anticyclonic gyre formed between 45degrees and 60degreesn with a cool water mass centered west of ireland where glacial cooling reached a maximum of 12degreesc in the subtropical ocean gyres the new reconstruction supports the glacial to interglacial stability of sst as shown by climap project members climap 1981 the zonal belt of minimum sst seasonality between 2degrees and 6degreesn suggests that the lgm caloric equator occupied the same latitude as today in contrast to the climap reconstruction the glacial cooling of the tropical east atlantic upwelling belt reached up to 6degrees 8degreesc during northern hemisphere summer differences between these simmax based and published u37 k and mg ca based equatorial sst records are ascribed to strong sst seasonalities and sst signals that were produced by different planktic species groups during different seasons

north atlantic circulation and reservoir age changes over the past 41 000 years 1 constraints on the timing of atlantic meridional overturning circulation amoc changes during the last deglaciation are fundamental to understanding the climate s rapid response to insolation forcing however uncertainty about high latitude north atlantic hlna radiocarbon reservoir ages has previously precluded robust age model development for this critical region hlna reservoir ages also serve as a proxy for amoc strength we present regionally averaged hlna reservoir ages for 0 to 41 thousand years before the present kyr bp based on over 500 radiocarbon dates from 33 north atlantic cores an early deglacial increase to 1000 14c yr reservoir ages between 18 5 and 16 5 kyr bp suggests reduced amoc before peak heinrich stadial 1 hs1 ice rafted debris ird a rapid decrease in reservoir ages coincident with the ird maximum at 16 kyr bp indicates strong stratification of the upper water column caused by massive freshwater release

refined modeling and14c plateau tuning reveal consistent patterns of glacial and deglacial14c reservoir ages of surface waters in low latitude atlantic atlantic surface water reservoir ages

marine radiocarbon reservoir age simulations for the past 50 000 years radiocarbon 14c dating calibration for the last glacial period largely relies on cross dated marine 14c records however marine reservoirs are isotopically depleted with respect to the atmosphere and therefore have to be corrected by the marine radiocarbon ages of surface waters mras whose temporal variabilities are largely unknown here we present simulations of the spatial and temporal variability in mras using a three dimensional ocean circulation model covering the past 50 000 years our simulations are compared to reconstructions of past surface ocean 14c running the model with different climatic boundary conditions we find that low latitude to midlatitude mras have varied between 400 and 1200 14c years with values of about 780 14c years at the last glacial maximum reservoir ages exceeding 2000 14c years are simulated in the polar oceans our simulation results can be used as first order approximation of the mra variability in future radiocarbon calibration efforts

lidar observations of gravity wave activity in the upper stratosphere over toronto the rayleigh lidar technique has been applied to observe temperature fluctuations induced by gravity waves within the upper stratosphere observations were carried out on a routine basis for 1 year 130 clear nights at the campus of york university near toronto 44 n 80 w the waves were on occasion observed to induce marginal convective instability while exhibiting no substantial vertical amplitude growth in general the vertical variation in the amplitude of fractional temperature perturbations and associated available potential energy density implied the waves were strongly dissipated dramatic changes in the distribution of spectral energy with respect to vertical wave number were observed over the course of a few hours the total resolved available potential energy in the gravity wave field varied considerably from day to day and seasonally with a winter maximum and summer minimum

temperature sensitivity of planktic foraminifera and its influence on the oxygen isotope record abstract we used oxygen isotope measurements from holocene surface sediments to infer optimum temperature and temperature sensitivity of the planktic foraminiferal species globigerinoides ruber pink and globigerinoides sacculifer the isotopic optimum temperature of g ruber pink is close to 27 c g sacculifer seems to have optimum vital conditions around 22 c and is less temperature sensitive than g ruber pink our estimations of optimum temperature and temperature sensitivity are in good accordance with laboratory and field investigations two simple experiments show that the temperature sensitivity of planktic foraminifera determined from oxygen isotopes can influence phase and amplitude of oxygen isotope records if the temperature distribution at the sea surface changes through time to use this distortion for paleoceanography we suggest to derive an isotopic transfer function which allows the calculation of average temperature temperature variability and the isotopic composition of seawater if the oxygen isotope differences between at least three species are known

mass change calculations in altered rock series a technique is presented whereby precursors of altered rocks in a fractionated rock series can be identified and changes in chemical components mass and volume accurately calculated the procedure utilizes elements with high degrees of immobility in hydrothermal and associated interactive water rock systems igneous rock series and sedimentary and metamorphic rocks with primary continuity of chemical composition are amenable to this treatment in the procedure for igneous rocks best fit fractionation lines are established for an immobile igneous compatible incompatible element pair the latter element functioning as the fractionation monitor alteration paths are linear and pass through the origin intersections of the fractionation and alteration lines yield the immobile element concentrations in the precursors to the altered rocks mobile components are determined from fractionation lines and monitor values total mass changes are proportional to the displacement of altered samples from the fractionation line masses of other elements in an altered sample reconstructed values are recalculated to the concentration of the monitor element in the precursor chemical changes are the differences between the calculated precursor compositions and the reconstructed altered rock compositions errors are mainly a function of the positioning of the fractionation lines

ventilation of the glacial deep pacific ocean measurements of the age difference between coexisting benthic and planktic foraminifera from western equatorial pacific deep sea cores suggest that during peak glacial time the radiocarbon age of water at 2 kilometers depth was no greater than that of today these results make unlikely suggestions that a slowdown in deep ocean ventilation was responsible for a sizable fraction of the increase of the ratio of carbon 14 14c to carbon in the atmosphere and surface ocean during glacial time comparison of 14c ages for coexisting wood and planktic foraminifera from the same site suggests that the atmosphere to surface ocean 14c to c ratio difference was not substantially different from today s

high resolution radiocarbon records trace episodes of zoophycos burrowing the unknown zoophycos producing organism potentially reworks marine sediments far deeper up to 1 m than common bioturbational mixing of the topmost sediment layer the zoophycos producer displaces planktonic foraminifera tests down to deep sediment levels hence may seriously bias the faunal and isotopic composition and in particular the radiocarbon age 14c of the ambient host sediment here we present three high resolution 14c records from sediment cores retrieved at intermediate water depths off brazil new zealand and norway where zoophycos burrows have biased 14c ages by 1000 5000 years based on closely spaced 14c ages and 14c plateau tuning we distinguish particular episodes with enhanced zoophycos production that coincide with time spans of decreased sedimentation and thus with probably reduced benthic nutrition off new zealand the actual burrowing activity was dated close to the bolling allerod younger dryas boundary displaced grains are traced from the ancient sediment surface of the younger dryas as far back as to the onset of heinrich stadial 1 and the terminal last glacial maximum these displaced 14c ages and similar 14c records obtained from two other sediment cores suggest that zoophycos producers generally mount a burrowing campaign during times when environmental conditions are switching toward a starved sedimentation regime during these tipping points zoophycos spreiten probably serve as storage space for nutrient rich particles foraged at the sediment surface and bioturbational mixed layer

petrologie du granite peralcalin du lac brisson labrador central nouveau quebec ii mineralogie et modalites de cristallisation mineral zonation in the quebec labrador brisson lake peralkaline granite displays quartzose and feldspathic lithofacies arranged concentrically the latter occupying the centre of the intrusion the zonation is the result of successive magmatic pulses in the feldspathic facies agpaitic crystallization began under hypersolvus conditions around 720 c with pf 0 1 gpa subsolvus crystallization involving enrichment of the residual liquid in f continued to below 500 c the quartzose facies is more differentiated and its composition was controlled by feldspar fractionation early quartz crystallization is partly explained by the high content of f in the magma the mafic mineral succession is in both facies li and zn rich arfvedsonite with an important ferrorichterite component which crystallized along with alkali feldspar under low aenigmatite contemporary of amphibole or anterior destabilized to form neptunite astrophyllite aegirine or arfvedsonite primary titaniferous aegyrine contemporary w

coccolithophore paleoproductivity and ecology response to deglacial and holocene changes in the azores current system 1 in order to test the sensitivity of marine primary productivity in the midlatitude open ocean north atlantic to changes in the atlantic meridional overturning circulation amoc we investigated two spliced sediment cores from a site south of the azores islands at the northern rim of the north atlantic subtropical gyre for this purpose we analyzed coccolithophore assemblages diatom abundances alkenones and conducted x ray fluorescence xrf core scanning during times of reduced amoc especially during heinrich event 1 h1 and the younger dryas we observe a strong increase in productivity as evidenced by high coccolith accumulation rates high alkenone concentrations accumulation rates high ba ti ratios high abundances of diatoms and low abundances off profunda the increased productivity is partly caused by a more southern position of the azores front azf and hence by a less northward extension of the subtropical gyre as deduced from high abundances of the temperate coccolithophore species g muellerae and low abundances of subtropical species oolithotus spp umbellosphaera spp umbilicosphaeraspp however to explain the full range of the observed productivity increase other factors like increased westerly winds and advection of nutrient rich surface waters have also to be considered because this pattern can also be observed in other sediment cores from the midlatitude north atlantic we propose that during times of reduced amoc there has been a band of strongly increased productivity across the north atlantic at the northern rim of the contracted subtropical gyre which partly counteracts the decreased organic carbon pump in the high northern latitudes

lidar observations of persistent gravity waves with periods of 3 10 h in the antarctic middle and upper atmosphere at mcmurdo 77 83 s 166 67 e persistent dominant and large amplitude gravity waves with 3 10 h periods and vertical wavelengths 20 30 km are observed in temperatures from the stratosphere to lower thermosphere with an fe boltzmann lidar at mcmurdo antarctica these waves exhibit characteristics of inertia gravity waves in case studies yet they are extremely persistent and have been present during every lidar observation we characterize these 3 10 h waves in the mesosphere and lower thermosphere using lidar temperature data in june from 2011 to 2015 a new method is applied to identify the major wave events from every lidar run longer than 12 h a continuous 65 h lidar run on 28 30 june 2014 exhibits a 7 5 h wave spanning 60 h and 6 5 h and 3 4 h waves spanning 40 and 45 h respectively over the course of 5 years 323 h of data in june reveal that the major wave periods occur in several groups centered from 3 5 to 7 5 h with vertical phase speeds of 0 8 2 m s these 3 10 h waves possess more than half of the spectral energy for 93 of the time a rigorous prewhitening postcoloring technique is introduced for frequency power spectra investigation the resulting spectral slopes are unusually steep 2 7 below 100 km but gradually become shallower with increasing altitude reaching about 1 6 at 110 km two dimensional fast fourier transform spectra confirm that these waves have a uniform dominant vertical wavelength of 20 30 km across periods of 3 5 10 h these statistical features shed light on the wave source and pave the way for future research

early holocene planktic foraminifers record species specific 14c reservoir ages in arctic gateway to trace spatial variations in holocene reservoir ages of surface and subsurface waters we studied narrowly spaced 14c records of planktic foraminifera in three high sedimentation rate cores from the nordic seas the barents sea continental margin and eastern fram strait the two northern cores reveal a distinct early holocene 14c plateau in dates on the subsurface dweller neogloboquadrina pachyderma at 9 3 9 1 14c ka the plateau was tuned to an atmospheric 14c plateau at 9 0 8 7 14c ka that spans 10 2 9 6 calendar ka these two plateau boundaries provide robust age control points to estimate short term changes in sedimentation rate and to correlate paleoceanographic signals over 900 km along the west spitsbergen current the difference between planktic and atmospheric 14c plateau ages suggests local 14c reservoir ages of 370 400 yr planktic foraminifera species that inhabit different water masses document different reservoir ages by comparison the subpolar n incompta reveals a reservoir age of 150 yr probably formed in well mixed atlantic sourced waters during winter the near surface dweller turborotalita quinqueloba shows an age of 290 yr in the fram strait but one of 720 yr at the barents sea continental margin the latter age suggests a calcification within old meltwater enriched arctic surface waters admixed by the east spitsbergen current likewise we assign an elevated reservoir age of 760 yr on mixed species at a norwegian sea site near 71 n to preboreal meltwaters that spread from northern norway far west also documented by the spatial distribution of a coeval 13c minimum of n pachyderma

a complete terrestrial radiocarbon record for 11 2 to 52 8 kyr b p radiocarbon 14c provides a way to date material that contains carbon with an age up to 50 000 years and is also an important tracer of the global carbon cycle however the lack of a comprehensive record reflecting atmospheric 14c prior to 12 5 thousand years before the present kyr b p has limited the application of radiocarbon dating of samples from the last glacial period here we report 14c results from lake suigetsu japan 35 35 n 135 53 e which provide a comprehensive record of terrestrial radiocarbon to the present limit of the 14c method the time scale we present in this work allows direct comparison of lake suigetsu paleoclimatic data with other terrestrial climatic records and gives information on the connection between global atmospheric and regional marine radiocarbon levels

consistent dating for antarctic and greenland ice cores we are hereby presenting a new dating method based on inverse techniques which aims at calculating consistent gas and ice chronologies for several ice cores the proposed method yields new dating scenarios simultaneously for several cores by making a compromise between the chronological information brought by glaciological modeling i e ice flow model firn densification model accumulation rate model and by gas and ice stratigraphic constraints this method enables us to gather widespread chronological information and to use regional or global markers i e methane volcanic sulfate beryllium 10 tephra layers etc to link the core chronologies stratigraphically confidence intervals of the new dating scenarios can be calculated thanks to the probabilistic formulation of the new method which takes into account both modeling and data uncertainties we apply this method simultaneously to one greenland ngrip and three antarctic epica dome c epica dronning maud land and vostok ices cores and refine existent chronologies our results show that consistent ice and gas chronologies can be derived for depth intervals that are well constrained by relevant glaciological data in particular we propose new and consistent dating of the last deglaciation for greenland and antarctic ice and gas records

timed saber observations of global gravity wave climatology and their interannual variability from stratosphere to mesosphere lower thermosphere the present study for the first time reports the global gravity wave activity in terms of their potential energy derived from timed saber observations right from the stratosphere to the mesosphere lower thermosphere mlt region the potential energy profiles obtained from saber temperature are validated by comparing them with ground based lidar observations over a low latitude site gadanki 13 5 n 79 2 e the stratospheric and mesospheric global maps of gravity wave energy showed pronounced maxima over high and polar latitudes of the winter hemisphere the interannual variability of the stratospheric gravity wave activity exhibited prominent annual oscillation over mid latitudes the equatorial gravity wave activity exhibited quasi biennial oscillation in the lower stratosphere and semi annual oscillation in the upper stratosphere the mlt region maps revealed summer hemispheric maxima over polar latitudes and secondary maxima over the equatorial region the results are discussed in the light of present understanding of global gravity wave observations the significance of the present study lies in emphasizing the importance of satellite measurements in elucidating gravity waves which is envisaged to have profound impact on parameterizing these waves

the origins of late stage rocks in the st austell granite a re interpretation the origin of the granite varieties present in the st austell granite body biotite granite megacrystic and non megacrystic lithium mica granite fluorite granite is discussed in the light of new petrographic chemical and experimental evidence there were essentially two stages of magmatic activity the first represented by the intrusion of several phases of biotite granite the second by a later intrusion of non megacrystic lithium mica granite which crystallized from a volatile rich residual differentiate of the biotite granite magma both intrusions suffered hydrothermal alteration which primarily involved at least two stages of exchange of components via a single aqueous fluid phase within the non megacrystic lithium mica granite topaz and lithium mica were among the first phases to break down releasing f and li to this aqueous phase f was locally fixed as fluorite removing ca derived from the host biotite granite from the fluid and giving rise to pockets of fluorite granite apart from losing ca from plagioclase the biotite granite gained li expressed as lithium rich mica resulting in an aureole of megacrystic lithium mica granite surrounding the second intrusion at least one pervasive hydrothermal system using joints and grain boundaries as fluid pathways may have been in existence water rock interaction during fluid circulation is believed to have modified considerably the composition of predominantly meteoric water to give rise to the hydrothermal fluid responsible for greisening and mineralization within its sphere of influence the alteration phenomena initiated by the proposed hydrothermal system may have culminated in the formation of the major kaolinite deposits currently worked in the area

graphite ch4 h2o co2 equilibria at low grade metamorphic conditions equilibrium calculations and published phase equilibria are used to show that at temperatures below 400 c and pressures above 300 bar the fluids coexisting with graphite in the c o h system consist either of co2 h2o mixtures or ch4 h2o mixtures bulk fluid compositions consisting of ch4 h2o will unmix to methane rich fluid and h2o rich liquid at temperatures below about 325 c compositions on the co2 h2o join will unmix only at temperatures below about 275 c oxygen fugacity in the ch4 h2o graphite three phase region is fixed at constant p and t and approximately equal to that of the quartz magnetite fayalite assemblage in the co2 h2o graphite three phase region oxygen fugacity is about three orders of magnitude greater from the end stages of diagenesis to temperatures of 300 c and possibly 400 c in salt rich systems many metamorphic rocks may contain ch4 h2o fluids rather than co2 h2o mixtures thus metamorphic reactions involving carbonate minerals would involve ch4 graphite and h2o rather than co2 the immiscibility between ch4 and h2o could result in the common occurrence of methane natural gas in low grade metamorphic terrains

variability in mid depth ventilation of the western atlantic ocean during the last deglaciation negative stable carbon isotopic excursions have been observed throughout most of the mid depth 1000 3000 m atlantic ocean during heinrich stadial 1 hs1 and the younger dryas yd although there is an agreement that these mid depth excursions were in some way associated with a slowdown of the atlantic meridional overturning circulation amoc there is still no consensus on the precise mechanism s here we present benthic stable carbon and oxygen isotopic 13c and 18o records from five cores from the western equatorial atlantic wea together with published benthic isotopic records from nearby cores we produced a wea depth transect 800 2500 m we compare hs1 and yd data from this transect with data from previously published north and south atlantic cores and demonstrate that the largest negative 13c excursions occurred in the wea during these times moreover our benthic 18o records require the presence of two water masses flowing from the southern ocean bisected by a northern component water ncw given that 18o is a conservative water mass tracer we suggest that 13c was decoupled from water mass composition and does not correspond to simple alternations between northern and southern sourced waters instead 13c behaved non conservatively during hs1 and the yd consistently with our new 231pa 230th record from the wea transect that allowed the reconstruction of amoc strength we hypothesize that the negative 13c excursions reflect an increase in the residence time of ncw in response to a weakened amoc allowing for a marked accumulation of 13c depleted respired carbon at the mid depth wea

mg ca of globorotalia inflata as a recorder of permanent thermocline temperatures in the south atlantic 1 we present a species specific mg ca calcification temperature calibration for globorotalia inflata from a suite of 38 core top samples from the south atlantic from 8 s to 49 s g inflata is a deep dwelling planktonic foraminifer commonly occurring in subtropical to subpolar conditions which qualifies it for reconstructions of the permanent thermocline apparent calcification depths and calcification temperatures were determined by comparing measured 18o with equilibrium 18o of calcite based on water column properties based on our core top samples g inflata apparent calcification depth is constant throughout the south atlantic midlatitudes with a depth of 350 400 m within the permanent thermocline the resulting mg ca calcification temperature calibration is mg ca 0 72 0 045 0 042 exp 0 076 0 006 calcification temperature r2 0 81 and covers the temperature range 3 1 c 16 5 c we applied our mg ca calibration to gravity core ps2495 3 from the mid atlantic ridge at 41 s to test its validity by reconstructing a low resolution record covering the last two glacial interglacial cycles our paleotemperature record reveals large changes in temperature for terminations i and ii when permanent thermocline temperature increased by as much as 8 c the g inflata paleotemperature record suggests that oceanic fronts repeatedly migrated over the location of core ps2495 3 during the last 160 kyr this study shows the potential of g inflata mg ca to reconstruct paleotemperatures in the permanent thermocline

no evidence for a deglacial intermediate water δ14c anomaly in the sw atlantic abstract the last deglaciation was characterized by an increase in atmospheric pco 2 and decrease in atmospheric radiocarbon activity one hypothesis is that these changes were due to out gassing of 14 c depleted carbon from the abyssal ocean reconstructions of foraminiferal 14 c from the eastern tropical pacific arabian sea and high latitude north atlantic show that severe depletions in 14 c occurred at intermediate water depths during the last deglaciation it has been suggested that 14 c depleted water from the abyss upwelled in the southern ocean and was then carried by antarctic intermediate water aaiw to these sites however locations in the south pacific in the direct path of modern day aaiw do not exhibit the 14 c excursion and therefore cast doubt upon the aaiw mechanism de pol holz et al 2010 rose et al 2010 here we evaluate whether or not a deglacial 14 c anomaly occurred at intermediate depths in the southwest atlantic we find that the deglacial benthic 14 c trend at our site is similar to the atmospheric 14 c trend our results are also largely consistent with results from u th dated corals at shallower water depths on the brazil margin mangini et al 2010 we find no evidence in the southwestern atlantic of a 300 decrease in intermediate water 14 c from 18 to 14 kyr bp like that observed in the eastern tropical pacific marchitto et al 2007 when our results are paired with those from the south pacific it appears aaiw did not carry a highly 14 c depleted signal during the deglaciation another source of carbon is apparently required to explain the intermediate depth 14 c anomalies in the north atlantic indian and pacific oceans

reply to comment by t c birkett and r r miller on the role of hydrothermal processes in the granite hosted zr y ree deposit at strange lake quebec labrador evidence from fluid inclusions

ventilation of the deep southern ocean and deglacial co2 rise past glacial interglacial increases in the concentration of atmospheric carbon dioxide co2 are thought to arise from the rapid release of co2 sequestered in the deep sea primarily via the southern ocean here we present radiocarbon evidence from the atlantic sector of the southern ocean that strongly supports this hypothesis we show that during the last glacial period deep water circulating around antarctica was more than two times older than today relative to the atmosphere during deglaciation the dissipation of this old and presumably co2 enriched deep water played an important role in the pulsed rise of atmospheric co2 through its variable influence on the upwelling branch of the antarctic overturning circulation

observations of horizontal and vertical wave number spectra of gravity wave motions in the stratosphere and mesosphere over the mid pacific we present vertical and horizontal wave number spectra of density perturbations in the upper stratosphere 25 40 km and the upper mesosphere 80 105 km inferred from 45 hours of airborne na rayleigh lidar observations in the vicinity of hawaii the mean density variance is 0 92 2 for the upper stratosphere and 6 1 2 and for the upper mesosphere the mean vertical shear variance and richardson s number for the upper mesosphere are 6 1 km 2 and 0 69 respectively the observed vertical wave number m and horizontal wave number k spectra exhibit power law dependencies the mean slopes of the vertical wave number spectra are 2 5 for the upper stratosphere and 3 1 for the upper mesosphere the mean slope of the horizontal wave number spectra is 1 9 for the upper mesosphere the mean characteristic vertical and horizontal wavelengths inferred from the spectra are 13 4 and 5810 km respectively in all cases the magnitudes of the upper stratosphere m spectra are more than an order of magnitude smaller than those of the upper mesosphere at all observable scales in the stratosphere the m spectra exhibit significant energy at low wave numbers that are less than the values expected for the characteristic wave numbers this suggests the presence of gravity wave sources capable of generating significant energy at long vertical scales the source is believed to be geostrophic adjustment of the jet stream a large amplitude highly coherent quasi monochromatic short horizontal scale h 16 km oscillation in the na layer was observed on the march 22 flight the oscillation resembled short horizontal scale structures often observed in oh airglow images and was found to be consistent with a gravity wave interpretation

vapor undersaturated experiments with macusani glass h 2 o at 200 mpa and the internal differentiation of granitic pegmatites vapor undersaturated fractional crystallization experiments with macusani glass macusanite a peraluminous rhyolite obsidian at 200 mpa yield mineralogical fabrics and zonation and melt fractionation trends that closely resemble those found in zoned granitic pegmatites and other granitoids of comparable composition typically peraluminous li be ta rich deposits the zonation from the edge of charges inward is characterized by 1 fine grained sodic feldspar quartz border zones 2 a fringe of very coarse grained graphic quartz feldspar intergrowths that flair radially toward melt and terminate with nearly monophase k feldspar 3 cores of very coarse grained nearly monominerallic quartz or virgilite lialsi5o12 mica and 4 late stage fine grained albite mica intergrowths that are deposited from alkaline na rich interstitial melt at vapor saturation similar experimental products have been observed in compositionally simpler less evolved systems liquid lines of descent from initially h2o undersaturated runs are marked by a decrease in sio2 and increases in na k b p f h2o and a variety of trace lithophile cations these trends are believed to be governed by three factors 1 disequilibrium growth of feldspars quartz via metastable supersaturation 2 fractionation of melt toward sio2 depleted na rich compositions due to increases in b p and f and 3 changes in nucleation and growth rates mostly as a function of the h2o content of melt x w m in contrast experiments that are cooled below the liquidus from the field of melt aqueous vapor london et al 1988 fail to replicate pegmatitic characteristics in most respects on the basis of these and other experiments we suggest that the formation of pegmatite fabrics stems primarily from fractional crystallization in volatile rich melts and that enrichments in normally trace lithophile elements result from melt differentiation trends toward increasingly alkaline silica depleted compositions although vapor saturation at near solidus and subsolidus conditions may promote extensive recrystallization an aqueous vapor phase does not appear to be necessary for the generation of most of the salient characteristics of pegmatites