revised palaeoclimatic significance of mueller glacier moraines southern alps new zealand a sequence of late holocene moraines on the foreland of the mueller glacier southern alps new zealand forms part of a local moraine age database used to establish a regional glacier chronology and subsequently to investigate potential intra hemispheric and global climate forcing mechanisms we present new sedimentological and geomorphological evidence that a set of these moraine ridges previously considered to represent individual advances constitutes a single moraine complex the mueller memorial moraine formed by supraglacial transport of a large volume of landslide debris to the glacier terminus because a moraine formed in this way is not necessarily associated with an advance triggered by a climate event we question the palaeoclimatic significance of the mueller memorial moraine as well as that of other moraines in comparable settings our findings suggest that the mode of formation and glacio dynamical context of moraines whose ages contribute to existing palaeoclimate reconstructions need to be re examined in order to assess the reliability of these reconstructions copyright 2015 john wiley sons ltd

lichenometric and radiocarbon dating of holocene glaciation cordillera blanca peru hfeasurements of rliizocurpoii subgenus rliizocurpo r thalli on moraines the ages of which are constrained by six radiocarbon dates two pre colombian structures and one historically dated flood dep6sit indicate that lichenometry can be used to estimate the age of stabilization of glacial deposits that date to the last c 7 ka on the west side of the cordillera blanca perlj 8 40 9040 s 77 00 77 40 w the preliminary growth curve for subgenus rtiizocurpan resembles those derived for alpine areas in alaska and colorado and can be subdivided into an initial rapid phase of growth c 0 4 mm yr that lasts c 100 years a c 500 to 1000 year long phase of decelerating growth and a period of slow linear growth 0 016 mm yr that commences after c loo0 years size clustering of subgenus riiizocurpoir thalli supports a four fold subdivision of cirque moraines at altitudes between 4200 and 4650 m the oldest moraines stabilized between c 7000 and 6ooo bp and the three younger groups between c 3350 and 1600 bp between c 1250 and 400 bp and within the last 100 years this subdivision is supported by limiting radiocarbon dates from the cordillera blanca and from several cordilleras in southern peni and indicates that the holocene glacial chronology of the cordillera blanca is the most complete heretofore recognized in the tropical andes

geophone orientation and coupling in three component sea floor data a case study we analyse the geophone orientation and coupling in a data set from the north sea based on the polarization of the water break on the sea floor we have derived processing algorithms for determining the receiver orientation for gimballed and non gimballed geophone systems for a gimballed system the problem reduces to a simple horizontal rotation however for a non gimballed system where all three geophone axes may vary due to varying acquisition conditions such as dipping sea floor twisting of recording cable etc the three orientation angles cannot be found directly from the recorded displacement vectors using the data redundancy within a common receiver gather a robust two stage method is derived for the non gimballed system in which all three orientations can initially be unknown testing on the north sea data set acquired with a gimballed system shows that the three component geophones in the data set are orientated satisfactorily within an error of 5 however there are some undesirable cross couplings between the vertical and horizontal geophones which results in leakage of shear wave energy from the horizontal components to the vertical components

quaternary glaciations in the northern andes venezuela colombia and ecuador abstract the nature and distribution of glacial drift in the high andes of venezuela colombia and ecuador suggest that deposits of only the last two quaternary glaciations isotope stages 6 and 4 2 are present the penultimate glaciation in ecuador may be represented by deeply weathered drift that is beyond the range of radiocarbon dating in colombia and venezuela subdued moraines covered with loess may be of equivalent age in places this drift extends 1000 m lower in altitude than the limits of the last glaciation which comonly reach 3400 3600 m radiocarbon dated organic deposits 33 43 ka bp lying between tills composing superposed terminal moraines suggest that andean glaciers may have been as extensive during isotope stage 4 as during isotope stage 2 a relatively long interstadial from 43 33 ka bp preceded the glacier advance that culminated during the interval ca 28 15 ka bp two late glacial stadials are marked by moraine complexes at 3900 4200 m altitude they are partly constrained by radiocarbon ages of 12 9 ka bp and 12 10 ka bp moraines apparently deposited during neoglacial advances of the last ca 5 ka lie in front of most of the glaciers remaining in the northern andes

a major widespread climatic change around 5300 cal yr bp at the time of the alpine iceman palaeoenvironmental and archaeological data from arbon bleiche lake constance switzerland give evidence of a rapid rise in lake level dated by tree ring and radiocarbon to 5320 cal yr bp this rise event was the latest in a series of three successive episodes of higher lake level between 5550 and 5300 cal yr bp coinciding with glacier advance and tree limit decline in the alps this west central european climate change may have favoured the quick burial and the preservation of the alpine iceman recently found in the tyrolean alps it has possible equivalents in many records from various regions in both hemispheres dating to 5600 5000 cal yr bp and corresponds to global cooling and contrasting patterns of hydrological changes this major mid holocene climate event marks the hypsithermal neoglaciation transition possibly resulting from a combination of different factors including orbital forcing changes in ocean circulation and variations in solar activity copyright 2004 john wiley sons ltd

detecting a fluid filled borehole using elastic waves from a remote borehole the interaction of a fluid filled borehole with incident elastic waves is an important topic for downhole acoustic measurements by analyzing the wave phenomena of this problem one can simulate the detection of a borehole target using a source receiver system in a remote borehole the analysis result shows that the wave signals from the target borehole are of sufficient amplitude even though the borehole size is small compared to wavelength consequently the target borehole can be detected when the two boreholes are far away from each other the result can be utilized to provide a method for testing downhole acoustic imaging tools

paleoenvironmental changes and glacial stades of the last 50 000 years in the cordillera central colombia using data from glacial geomorphology tephra soil stratigraphy and mineralogy palynology and radiocarbon dating a sequence of glacial and bioclimatic stades and interstades has been identified for the past ca 50 000 yr in the ruiz tolima massif cordillera central six cold stades separated by warmer interstades occurred before 48 000 between 48 000 and 33 000 between 28 000 and 21 000 from 16 000 to ca 14 000 ca 13 000 12 400 and ca 11 000 10 000 yr b p although the radiocarbon ages are minimum limiting ages obtained from tephra layers on top of tills the tills are not significantly older because most are bracketed by dated tephra sets in measured stratigraphic sections two minor moraine stages likely reflect glacier pauses during cold intervals ca 7400 yr b p and slightly earlier finally glaciers readvanced between the 17th and 19th centuries in contrast to the glacier cover ca 34 km2 on volcanoes of the massif during the last glacial maximum lgm the ice cover expanded to 1200 km2and was still 800 km2during late glacial time lgt glacier reconstructions based on the moraines suggest depression of the equilibrium line altitude ela by ca 1100 m during the lgm and 500 600 m during lgt relative to the modern ela which lies at ca 5100 m in the cordillera central glaciers in this region apparently reached their greatest extent when the climate was cold and moist e g during stades corresponding to marine isotope stage 3 glaciers were still expanding during the lgm ca 28 000 21 000 yr b p but they shrank considerably after 21 000 yr b p because of greatly reduced precipitation

synchronism of holocene east asian monsoon variations and north atlantic drift ice tracers eighteen radiocarbon dated eolian and paleosol profiles within a 1500 km long belt along the arid to semi arid transition zone of north central china record variations in the extent and strength of the east asian summer monsoon during the holocene dated paleosols and peat layers represent intervals when the zone was dominated by a mild moist summer monsoon climate that favored pedogenesis and peat accumulation brief intervals of enhanced eolian activity that resulted in the deposition of loess and eolian sand were times when strengthened winter monsoon conditions produced a colder drier climate the monsoon variations correlate closely with variations in north atlantic drift ice tracers that represent episodic advection of drift ice and cold polar surface water southward and eastward into warmer subpolar water the correspondence of these records over the full span of holocene time implies a close relationship between north atlantic climate and the monsoon climate of central china

the evolution of the patagonian ice sheet from 35 ka to the present day patice abstract we present patice a gis database of patagonian glacial geomorphology and recalibrated chronological data patice includes 58 823 landforms and 1 669 geochronological ages and extends from 38 s to 55 s in southern south america we use these data to generate new empirical reconstructions of the patagonian ice sheet pis and subsequent ice masses and ice dammed palaeolakes at 35 ka 30 ka 25 ka 20 ka 15 ka 13 ka synchronous with the antarctic cold reversal 10 ka 5 ka 0 2 ka and 2011 ad at 35 ka the pis covered of 492 6 x103 km2 had a sea level equivalent of 1 496 mm was 350 km wide and 2090 km long and was grounded on the pacific continental shelf edge outlet glacier lobes remained topographically confined and the largest generated the suites of subglacial streamlined bedforms characteristic of ice streams the pis reached its maximum extent by 33 28 ka from 38 s to 48 s and earlier around 47 ka from 48 s southwards net retreat from maximum positions began by 25 ka with ice marginal stabilisation then at 21 18 ka which was then followed by rapid irreversible deglaciation by 15 ka the pis had separated into disparate ice masses draining into large ice dammed lakes along the eastern margin which strongly influenced rates of recession glacial readvances or stabilisations occurred at least at 14 13 ka 11 ka 6 5 ka 2 1 ka and 0 5 0 2 ka we suggest that 20th century glacial recession a 1 is occurring faster than at any time documented during the holocene

atmospheric circulation changes and neoglacial conditions in the southern hemisphere mid latitudes insights from pmip2 simulations at 6 kyr glacial geologic studies in the southern hemisphere sh mid latitudes 40 54 s indicate renewed glacial activity in southern south america patagonia and new zealand s nz south island starting at 7 kyr the so called neoglaciation available data indicate that neoglacial advances in these regions occurred during a rising trend in atmospheric co2 and ch4 concentrations lower than present but increasing summer insolation and seasonality contrasts in this paper we examine the climatological context in which neoglaciations occurred through analysis of the complete paleoclimate modelling inter comparison project pmip2 database of simulations at 6 kyr for the sh we observe that the amplitude of the annual insolation cycle in the sh did not change significantly at 6 kyr compared to the pre industrial values the largest difference occurring in autumn mam negative anomalies and spring son positive anomalies the simulated changes in temperatures over the sh respond to the insolation changes with a 1 2 month delay over the oceans this results in a reduced amplitude of the annual cycle of temperature and precipitation over most continental regions except over patagonia and nz that show a slight increase in contrast large scale circulation features such as the low and upper level winds and the subtropical anticyclones show an amplified annual cycle as a direct response to the increased decreased insolation during the transitional seasons son mam in the annual mean there is a small but consistent equatorward shift of the latitude of maximum wind speed of 1 3 over the entire sh which results in a small increase of wind speed over the south pacific and atlantic oceans north of 50 s and a widespread decline south of 50 s pmip2 simulations for 6 kyr indicate that in the annual mean the sh mid latitudes were colder wetter and with stronger winds north of about 50 s these conditions are consistent with the observed neoglacial advances in the region as well as with terrestrial paleoclimate records from patagonia that indicate cooling and a multi millennial rising trend in southern westerly wind intensity starting at 7 8 kyr

holocene glacier fluctuations in south america and antarctica abstract glacial geologic evidence indicates that glaciers throughout the andes and antarctica fluctuated during the holocene radiocarbon dating and other age determinations suggest that glaciers readvanced significantly only during the last 5 ka reaching positions from several 100 m to a few kilometres beyond their present limits in south america tenuous evidence from radiocarbon dates with dendrochronological data and environmental interpretations from pollen analyses indicate four main periods of neoglacial advance culminating 5000 4000 bp 3000 2000 bp 1300 1000 bp and 15th late 19th centuries smaller advances may have occurred at ca 8400 bp ca 7500 bp and ca 6300 bp the meagre data are consistent in indicating broad synchrony throughout the andes during the last 5 ka suggesting response to global climatic changes anomalies exist in patagonia where some tide water glaciers reached their maximal holocene limits recently this century the broad spectrum of differing antarctic environments produces interesting contrasts some local glaciers in the mcmurdo sound area of the east artarctic continent are more extensive now than during the global glacial maximum ca 18 ka bp when they were starved of precipitation consistent agreement among 14 radiocarbon dates from the south shetland islands indicates two main holocene glacier advances the most extensive 2 3 km peaking in the 12th century the other culminating in the 18th 19th century glaciers in south georgia reached their most advanced holocene limits before 2200 bp moraine fjord glacier which culminated as a 6 km advance between 1460 1700 radiocarbon bp may have lagged 400 650 years behind the climatic forcing because it could only advance in its deep water fjord by building a moraine bank smaller advances in south georgia culminated in the 17th 19th centuries and during the 1920s 30s there is no firm evidence of glacier advances before 3 ka bp in the southern ocean sub antarctic domain but broad synchrony in glacier advances during the last ca 3000 years appears to have occurred throughout the andes antarctic transect caution is required in the interpretation and correlation of moraines associated with calving glaciers and of those with poorly constrained dating

holocene climate in the atlantic sector of the southern ocean controlled by insolation or oceanic circulation abstractthe holocene climate of the southern ocean is not well un derstood mainly because of the lack of high resolution reconstruc tions of ocean surface properties here we present a 12 500 yr long decadal scale record of holocene sea surface temperatures and sea ice presence from the polar front of the east atlantic southernocean the record shows gradual climate change with no abruptneoglacial cooling and an unprecedented late holocene warming the dominant forcing factor appears to be precessional insolation northern hemisphere summer insolation correlates to at least theearly to middle holocene climate trend spectral analysis revealscentennial scale cyclic climate changes with periods of 1220 1070 400 and 150 yr the record shows good correlation to east ant arctic ice cores and to climate records from south georgia andbunger oasis however the record shows out of phase behaviorwith regard to climate records from the western antarctic penin sula and the peru chile current such behavior hints at a climaticdivide through patagonia the drake passage and between westand east antarctica keywords southern ocean paleoclimate diatoms modern analogtechnique holocene insolation antarctic polar front introductionthe holocene climate variability has received less attention thanthe more dramatic changes during the last glacial period the holoceneis generally assumed to be a stable interglacial period when climatechanges in the north atlantic are transmitted to the rest of the worldthrough a strong thermohaline circulation imbrie et al 1992 thelarge uctuations of the last glacial period appear to continue into thisinterglacial although in a subdued manner bond et al 2001 the southern ocean has received even less attention than the highnorthern latitudes oceanic records are few and coarse they generallydisplay a warm early holocene followed by cooling labracherie etal 1989 pichon et al 1992 hodell et al 2001 similar to northatlantic climate e g koc and jansen 1994 high resolution recordsare restricted to antarctic ice cores which mostly display little climatevariability during the holocene jouzel et al 2001 an exception isthe taylor dome deuterium record in which the holocene appears tobe split by an abrupt cooling event ca 5 5 5 ka steig et al 1998 this cooling appears to t the late holocene global cooling trend por ter 2000 as a nonlinear response from the climate system to insolationchanges demenocal et al 2000 hodell et al 2001 high resolution holocene records available for southern oceanclimate reconstruction are rarely from the antarctic circumpolar cur rent proper e g domack et al 2001 stenni et al 2001 lamy et al 2002 with the exception of a multiproxy approach to holocene cli mate that includes a high resolution description of lithic fragments hodell et al 2001 we present data from site tn057 17 near the polar front in theeast atlantic southern ocean it is based on quantitative estimates ofsummer sea surface temperature ssst and sea ice presence sip utilizing the down core variability of diatom assemblages the recordshows good correlation to antarctic ice cores but a gradual change inphase relationships during the early holocene the record shows anin phase relationship with the ross sea region ice cores during thelate holocene the record shows an in phase relationship with the eastantarctic region ice cores antarctic polar frontthe antarctic polar front apf fig 1 is an important climateboundary in terms of air sea uxes and the heat and salt budgets ofthe oceans at the surface the apf is a steep sea surface temperaturegradient while the subsurface expression is the southern limit for sub duction of cold fresh antarctic surface water below warmer and moresaline subantarctic surface water orsi et al 1995 globally the apfcould be the southern limit of synchrony with northern hemisphereclimate broecker 1996 the apf is subject to large spring and sum mer blooms of diatoms fischer et al 2002 and achieves the largestbiogenic sedimentation rates of the diatom ooze belt of the southernocean burckle and cirilli 1987 it is these high sedimentation ratesof diatomaceous oozes and the sensitivity of diatoms especially to lightand temperature that make sites in the apf region suitable for pro ducing high resolution records of climate change

geomorphological evidence for variations of the north patagonian icefield during the holocene abstract elucidating the timing and extent of former glacier fluctuations is important because of the palaeoclimatic inferences that can be drawn from such studies here we present new geomorphological evidence of the patterns of glacier behaviour around the north patagonian icefield during the holocene mapping is based on visual interpretation of landsat 7 etm and terra aster satellite images including the contemporary glaciers areas of ice scoured bedrock trimlines glacial lineations terminal moraines sandur and fluvial sediments deltas and ice contact deposits and alluvial fans recession of the icefield is marked by three distinct moraine sets these moraine sets are interpreted as marking terminal positions related to the little ice age and two preceding but as yet undated phases of holocene glacier expansion large arcuate terminal moraines in front of three of the western glaciers are interpreted as composite features reflecting topographic limits to glacier expansion indicating that caution is required in the interpretation of previous 14c dates obtained from these moraines there are strong contrasts in the patterns of glacier behaviour between the east and west sides of the north patagonian icefield which cannot be attributed simply to an east west differential in the rates of change of atmospheric temperature and precipitation we argue here that glacier response to first order climate forcing is tempered by second order controls introduced by regional scale topographic effects notably glacier drainage basin extent and area topographic controls on glacier snout morphology and differences in terminal environment calving non calving during glacier recession

estimates of late holocene soil production and erosion in the snowy mountains australia soil production in actively uplifting or high precipitation alpine landscapes is potentially rapid however these same landscapes are also susceptible to erosion and can be sensitive to changes in climate and anthropogenic activity which can upset the balance between soil production and erosion the snowy mountains southeastern australia are a tectonically stable low relief moderate precipitation mountain environment the alpine area is extensively blanketed by soil that has been subjected to more intensive episodes of erosion during past periods of anthropogenic disturbance and under cold climate conditions of the late quaternary in this study rates of soil development and hillslope erosion were investigated using radiocarbon dating fallout radionuclides and sediment cores collected from lakes and reservoirs estimated holocene soil development rates were 20 220 t km y erosion rates determined from the radionuclides cs and pb were equivocal due to the inherent spatial variability of radionuclide inventories relative to apparent erosion rates estimated average erosion rates over the past 100 years determined from pb inventories were 60 t km y 95 ci 10 90 inventories of cs observed at the same site implied that more recent erosion rates over the past 60 years was below the detection limits of the sampling method applied here i e 70 t km y the upper estimate of 90 t km y is comparable to the mean erosion rate estimated using the radionuclide method for uncultivated sites in australia and is significantly lower than that measured at sites were vegetation cover was disturbed by livestock grazing prior to its exclusion from the alpine area in the 1940s ce low erosion and high soil production rates relative to the lowland soils are likely related to extensive vegetation cover which in this context protects soils against erosion and contributes to the formation of organic alpine soils that rapidly accumulate organic matter by comparison to other soil types

onset of neoglaciation in the southern hemisphere a review of evidence documenting an early neoglacial mid holocene advance of mountain glaciers in south america and new zealand reveals that of 16 glaciers for which radiocarbon age control exists only two have associated dates that may approximate the culmination of an advance advances of the remaining glaciers are controlled only by minimum or maximum limiting ages additional dates for several new zealand glaciers are based on weathering rind measurements having large potential errors twelve of the glaciers now terminate or have terminated in lakes or in tidewater and are subject to instabilities associated with calving termini an extensive debris cover in the ablation zone of nearly half of the glaciers makes their moraine succession potentially suspect as a record of detailed climatic variation the two glaciers with seemingly reliable age control are located in valleys where large rock avalanches could affect glacier mass balance and lead to random advances or where rock avalanche deposits might easily be mistaken for moraines and tills the early neoglacial interval has been defined primarily based on this set of data the ages taken at face value suggest that the early neoglacial advance culminated between ca 5400 and 4900 cal yr ago ca 4600 4400 14c yr bp this chronology however should remain provisional until improved age control is obtained for a large population of glaciers based on closely bracketing radiocarbon dates and or an adequate number of cosmogenic isotope ages data from calving glaciers and those subject to rock avalanche activity should be avoided or assessed critically copyright 2000 john wiley sons ltd

millennial scale variability in southern hemisphere westerly wind activity over the last 5000 years in sw patagonia abstract here we report results from a high resolution palynological record and stratigraphic geochronologic data related to a neoglacial event in torres del paine national park southern chile 51 s 71 w to investigate climatic variations in southwest patagonia during the last 5000 years the record reveals a stepwise expansion of nothofagus dominated woodlands and forests with discrete pulses at 4400 2900 1300 and 570 cal yr bp superimposed upon this trend we identify a relative opening of the woodlands between 4100 2900 and 2300 1300 cal yr bp closed canopy forests dominated the landscape between 570 60 cal yr bp followed by a rapid decline at the end of the 19th century that coincided with intense fire activity and the appearance of rumex cf acetocella an exotic species introduced by european settlers we interpret these changes as variations in the intensity and or position of the southern margin of the westerly winds which culminated with a net eastward shift of the forest steppe ecotone during the little ice age we propose that millennial scale changes in either the latitudinal position and or the overall strength of the southern westerlies may be responsible for vegetation changes fire occurrence and the dynamic behavior of patagonian glaciers during the last 5000 years because the modern maximum in near surface wind velocities and precipitation is located between 48 and 50 s we suggest that the core of the southern westerlies may have achieved this modern position 570 years ago

holocene variations in productivity associated with changes in glacier activity and freshwater flux in the central basin of the strait of magellan article i nfo oneofthemostimportantfactorscontrollingfjordprimaryproductioninsouthernmostpatagoniaisthevariabil ity in the thermohaline structure of the water column in the present day environment thermal stratification is mostlyrelatedtofreshwaterinputandinparticular theseasonal melting ofglaciers here we assesswhether this relation between fjord productivity and freshwater input holds true for the holocene using a sediment record from thecentral basinofthestrait of magellan coremd07 3132 53 44 17 s 70 19 03 w 301 m our approach relies on a proxy based reconstruction of fjord sea surface temperature alkenone sst paleosalinity freshwater input and paleoproductivity the results indicate that during the early holocene the accumulation rate ar of marineorganic carbonwas low b20kgm 2 kyr 1 most likelyduetohigh freshwater contribution resulting in low salinity and low ssts after 8 5 kyr bp and during the mid and late holocene all the productivity proxies in crease the ar s of marine organic carbon 30kgm

tripartite climate reversal in central europe 5600 5300 years ago abstract the history of variations in water level of lake constance as reconstructed from sediment and pollen analysis of a sediment sequence from the archaeological site of arbon bleiche 3 shows an abrupt rise in lake level dendrochronologically dated to 5375 yr ago 5320 yr relative to ad 1950 this event paralleled by the destruction of the neolithic village by fire provoked the abandonment of this prehistoric lake shore location established in the former shallow bay of arbon bleiche and was the last of a series of three episodes of successively higher lake level the first occurring at 5600 5500 cal yr b p the dendrochronologically dated rise event was synchronous with an abrupt increase in atmospheric 14 c this supports the hypothesis of an abrupt climate change forced by varying solar activity moreover the three successive episodes of higher lake level between 5600 and 5300 cal yr b p at arbon bleiche 3 coincided with climatic cooling and or changes in moisture conditions in various regions of both hemispheres this period corresponds to the mid holocene climate transition onset of the neoglaciation and suggests inter hemispheric linkages for the climate variations recorded at arbon bleiche 3 this mid holocene climate reversal may have resulted from complex interactions between changes in orbital forcing ocean circulation and solar activity finally despite different seasonal hydrological regimes the similarities between lake level records from lake constance and from jurassian lakes over the mid holocene period point to time scale as a crucial factor in considering the possible impact of climate change on environments

abrupt cooling of antarctic surface waters and sea ice expansion in the south atlantic sector of the southern ocean at 5000 cal yr b p antarctic surface waters were warm and ice free between 10 000 and 5000 cal yr b p as judged from ice rafted debris and microfossils in a piston core at 53 s in the south atlantic this evidence shows that about 5000 cal yr b p sea surface temperatures cooled sea ice advanced and the delivery of ice rafted detritus ird to the subantarctic south atlantic increased abruptly these changes mark the end of the hypsithermal and onset of neoglacial conditions they coincide with an early neoglacial advance of mountain glaciers in south america and new zealand between 5400 and 4900 cal yr b p rapid middle holocene climate changes inferred from the taylor dome ice core antarctica cooling and increased ird in the north atlantic and the end of the african humid period the near synchrony and abruptness of all these climate changes suggest links among the tropics and both poles that involved nonlinear response to gradual changes in northern hemisphere insolation sea ice expansion in the southern ocean may have provided positive feedback that hastened the end of the hypsithermal and african humid periods in the middle holocene

testing models of mid to late holocene sea level change north queensland australia understanding the nature of global ice equivalent eustatic sea level changes during the mid to late holocene is important to our understanding of how ice sheets will respond to future climate change this study re analyses the indicative meaning and age control of existing relative sea level rsl data from cleveland bay north queensland australia and presents new rsl data from a foraminifera based transfer function as a preliminary test of global geophysical models in this region during the mid to late holocene the foraminifera based transfer function produces reliable rsl estimates consistent through the mid to late holocene at different locations in cleveland bay analysis of the combined rsl database reveals that rsl rose above present between 8 and 6 2 ka cal bp with the peak of the sea level highstand c 2 8 m above present at c 5 ka cal bp remaining relatively stable above 1 5 m from 6 2 until at least 2 3 ka cal bp falling to present in the last millennia this long period of sea level above present in the mid to late holocene suggests a gradual rather than abrupt end to global ice melt which must have continued into the late holocene this new analysis also shows no evidence for episodic fluctuations within the highstand although they cannot be entirely ruled out by this study this study demonstrates that more sea level data needs to be collected from locations uncontaminated by glacio isostasy hydro isostasy and tectonic effects in order to better constrain the late holocene melt histories of the large polar ice sheets

relative sea level change in west greenland during the last millennium relative sea level rsl data provide important long term century to millennial scale constraints on ice load history in greenland in this paper we present the results of a litho bio and chronostratigraphic study designed to reconstruct rsl during the last millennium from salt marsh deposits recovered from a field site near to the town of sisimiut west greenland the stratigraphy at three marshes typically records an upwards transition from freshwater to salt marsh deposits we use a quantitative transfer function and subjective model to reconstruct palaeomarsh elevation and changes in mean tide level mtl from 16 sediment profiles from these marshes these palaeomarsh elevations are placed in a chronological framework established by 18 radiocarbon dated index points both models yield similar results and show mtl rose from 0 60 0 20 m at c 600 cal a bp to reach 0 10 0 20 m at c 400 cal a bp after this time mtl remained close to present 0 20 m until the present day although low sedimentation rates limit the resolution of our reconstructions during this interval the initial rise in rsl can be explained by the dominance of non greenland processes notably the collapse of the laurentide forebulge over local greenland solid earth uplift caused by postglacial ice unloading this is despite some reloading of the crust that occurred during the neoglacial expansion of the greenland ice sheet in this part of west greenland the slow down in rsl at 400 cal a bp does not record either a change in the rate of laurentide forebulge collapse or a change in eustatic sea level we argue instead that this slow down records the effects of a sustained reduction in local greenland ice mass that persists over most of the past 400 years the latter interval is widely acknowledged as a period of generally cooler than present conditions associated with the later stages of the little ice age during this period field evidence suggests that in many areas the ice sheet had reached its maximum late holocene extent it is not obvious at this stage how to reconcile an expanding ice sheet with a reduction in ice load during this interval although we hypothesise it could reflect one or more of i a change in ice sheet dynamics ii reduced mass accumulation caused by cold and dry conditions and iii a lagged response to earlier periods of climate warming

major factors controlling holocene δ13corg changes in a seasonal sea ice environment adelie land east antarctica 1 in an effort to investigate the controlling factors behind holocene 13corg changes in east antarctica we report high resolution down core records of bulk organic matter carbon isotopic ratios 13corg diatom census counts total organic carbon and biogenic silica content taken from one core recovered in the adelie trough a good correspondence between the 13corg record and records of small large and pennate centric ratios in many of the core segments indicates that diatom species composition affected holocene 13corg variations possibly via diatom shape and size effects variations in the surface water co2 concentration and in the isotopic composition of the source during the holocene cannot be ruled out although they cannot explain rapid and large amplitude 13corg changes within the limit of our investigation our results argue against active carbon acquisition through a carbon concentration mechanism as evidenced in low latitude upwelling systems the bulk organic matter thus represents a mixing of diatom taxa having different fractionation affinity to aqueous co2 our results confirm previous evidence which demonstrates that 13corg down core records should be used with great caution to reconstruct past co2 content in surface waters

proglacial lake sediment records of holocene climate change in the western cordillera of peru abstract sediment records from proglacial lakes between 9 and 10 s in the western cordillera of the peruvian andes document the waxing and waning of alpine glaciers since the end of the lateglacial stage these records from the southern tropical andes provide supporting evidence that the early holocene between 12 and 8 ka was relatively warm and dry and the middle holocene between 8 and 4 ka was marked by a shift to cooler and possibly wetter conditions in certain regions leading to glacial advances although there were multiple periods of brief ice advances that interrupted the overall trend glaciers in multiple valleys generally retreated from 4 0 ka through the medieval climate anomaly 1 0 0 7 ka this late holocene pattern of ice retreat occurred during a period when lake level studies and both lacustrine and speleothem stable isotopic records indicate wetter conditions relative to the middle holocene suggesting that higher temperatures contributed to the pattern of ice retreat following this period of glacial retreat multiple proxy records suggest that the start of the little ice age 0 6 0 1 ka was a colder and wetter time throughout much of the tropical andes there appear to be two primary synoptic scale climatic controls on temperature and precipitation linked to insolation dynamics that drive changes in ice cover in the southern tropical andes during the holocene 1 the strength of the south america summer monsoon which is linked to northern hemisphere temperatures and the mean position of the intertropical convergence zone over the atlantic and 2 sea surface temperature distributions in the tropical pacific ocean and its influence on atmospheric temperature precipitation and circulation patterns

southern hemispheric westerlies control sedimentary processes of laguna azul south eastern patagonia argentina multiproxy investigations of lacustrine sediments from laguna azul 52 s document multi millennial holocene influences of southern hemispheric westerlies shw on the hydroclimatic variability of

holocene deglaciation and climate history of the northern antarctic peninsula region a discussion of correlations between the southern and northern hemispheres holocene deglaciation and climate history of the northern antarctic peninsula region a discussion of correlations between the southern and northern hemispheres

parsimonious migration of 3 c 3d vsp data conventional kirchhoff migration can be made much faster by a priori calculation of wave arrival directions and tracing rays back only along the measured directions this is known as parsimonious migration for surface seismic data where acquisition with 2d arrays is common the wave arrival directions can be measured by using local slant stacking to calculate the two horizontal slowness components the vertical slowness is then deduced by using the dispersion relation for vertical seismic profile vsp data where multiline acquisition is not possible only the vertical component of the slowness vector can be measured which is insufficient to constrain the wave arrival direction we overcome this limitation for three component vsp data by polarization analysis of the incident waves polar and azimuth anglesare calculated at the receivers by estimating the data covariance matrix and the vertical slowness assuming isotropic media and linear polarization of both p and s waves for p waves the data co

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

holocene glacier fluctuations in patagonia are modulated by summer insolation intensity and paced by southern annular mode like variability abstract alpine glaciers are sensitive indicators of changes in climate and their ubiquity in mountainous regions make them valuable proxies for terrestrial climate reconstructions worldwide however the timing and extent of glacier change across the south american mid latitudes through the holocene are still poorly constrained relative to their counterparts in the northern hemisphere here we report a new 10be surface exposure based chronology of moraines recording a series of progressively less extensive glacier advances of glaciar torre argentina 49 3 s 73 0 w since the last glacial maximum with expansions culminating at 17 600 900 13 500 500 9700 400 6900 200 6100 300 4500 200 and 530 60 yr bp the declining magnitude of holocene glacier expansions parallels a gradual rise in local summer insolation intensity during the holocene while individual advances occurred during inferred negative southern annular mode sam like states at centennial to millennial timescales these observations suggest that i summer insolation intensity modulated antiphased trends in glacier extent in the polar hemispheres during the holocene and that ii centennial scale sam like temperature and precipitation anomalies paced glacier fluctuations throughout patagonia given the persistence of the inferred sam like anomalies throughout the holocene the modern measured trend towards positive sam index conditions could mark the onset of a fundamental shift in the climate of the southern hemisphere midlatitudes that warrants consideration in projections of future climate

evidence for a rock avalanche origin for the hillocks moraine otago new zealand abstract a landform in otago new zealand previously interpreted as a glacial deposit has been investigated described and reinterpreted as a rock avalanche deposit the hillocks is a conspicuous cluster of small conical hills on the dart river floodplain the landform is protected under a local bylaw because of its identification as an outstanding example of a glacial kame deposit however the geological and geomorphological setting and the deposit morphology sedimentology and lithology suggest that it was formed by a large c 22 5 10 6 m 3 rock avalanche subsequent to glacial retreat and that the deposit temporarily dammed the dart river valley relative age dating evidence suggests that it is at least several hundred years old but younger than ca 7500 b p this work highlights the problem of paleoclimatic reconstructions using moraines as indicators of regional climate events despite similarities in form and in some cases sedimentology by applying an understanding of landslide initiation runout and depositional process we demonstrate that it is possible to distinguish the deposits produced by landslides from those produced by glacial deposition

reliability of a fjord glacier s fluctuations for paleoclimatic reconstructions abstract historical observations of fjord glaciers in southern alaska suggest that their fluctuations may be asynchronous with one another and with climate possible causes for anomalous fjord glacier response to climatic changes involve the instabilities inherent in a calving terminus the interaction of fjord geometry with the extent of the calving terminus and the intersection of low lying snow line by a thickening glacier the lituya glacier system in southeast alaska is analyzed with reference to these phenomena to test the reliability of its holocene glacial deposits as paleoclimatic records this fjord glacier is shown to have been probably free of major nonclimatic responses during the holocene except for an insensitive period of up to 1000 yr that followed calving retreats the insensitive period has no functional effect on how the relatively coarse geologic record is interpreted in terms of paleoclimate however it makes impossible any inference of climatic trends from this glacier s behavior in historical times fjord glacier deposits can be dependable records of paleoclimate but each glacier requires careful scrutiny anomalous glacier responses to climate are most likely to occur in fjords of complex geometry in regions of relatively low snow line and where glaciers terminate at fjord mouths bordering the open sea

oxygen isotope δ18o evidence of holocene hydrological changes at signy island maritime antarctica a record of holocene hydrological changes has been produced from variations in oxygen isotope composition delta 18 o preserved in freshwater lake sediments from maritime antarctica small amounts 5 of authigenic carbonate have been extracted from a non marl sediment core from sombre lake signy island 60 degrees 43 s 45 degrees 38 w oxygen isotope and particle size analysis provide a sensitive record of hydrological events in the lake arising from local and regional climate phenomena the climate affects delta o 18 through snowpack volume and glacier activity in the catchment lakewater temperatures the input versus evaporation balance and the duration of seasonal lake ice cover the most depleted negative delta o 18 values are associated with influxes of meltwater at times of glacier advance or retreat enriched positive delta o 18 values occur during more arid warmer conditions with longer periods of open water in summer this isotope record can be used to determine century scale to decadal variability in air circulation and moisture origin strong similarities with other holocene proxy records from the weddell sea and antarctic peninsula region are apparent including the mid holocene climate optimum followed by the neoglacial and most recently late twentieth century climatic warming the oxygen isotope record from sombre lake illustrates the importance of remote islands in contributing to our understanding of teleconnections in atmospheric and oceanographic circulation sea ice extent air temperatures and precipitation in the southern ocean

orientation of a downhole triaxial geophone the bearing and elevation of a geophone s axes are unknown when a geophone package is placed in a deep exploration borehole auxiliary instruments such as inclinometers compasses or gyros may be incorporated into the downhole package to give some indication of local attitude relative to some external reference field but these solutions may encounter difficulties because small gyros drift the geomagnetic field may be distorted locally or screened by casing and inclinometers add to the cost and weight of the downhole receiver an alternate approach to determining the orientation of a remote tool is to compare its triaxial response to that expected for a known elastic wavefield the accuracy of the measurement depends on the quality of the geophone to formation coupling and on the extent of one s knowledge of the externally impressed wavefield

nature and timing of quaternary glaciation in the himalayan tibetan orogen abstract much effort has been made in recent years to define the timing and extent of quaternary glaciation throughout the himalayan tibetan orogen these studies are challenging because of the logistical and political inaccessibility of the region and the inherent problems associated with the application of numerical dating techniques nevertheless the studies are providing abundant evidence for significant glacial advances throughout the last several glacial cycles and are beginning to accurately define the extent and timing of glaciation in selected regions studies are showing that himalayan tibetan glaciers in arid regions during the last glacial cycle reached their maximum extent early in the cycle and that global last glacial maximum glacier advances were significantly less extensive however along the more monsoonal influenced greater himalaya there is increasing evidence to suggest that glaciation was more extensive later in the last glacial cycle but this has yet to be fully assessed in addition the new studies are showing that throughout most himalayan tibetan regions significant glacier advances occurred during the lateglacial and early holocene with minor advances in some regions during the mid holocene the still relatively poor chronological control in the himalayan tibetan orogen however makes it difficult to construct correlations across the region and with regions elsewhere in the world this in turn makes it hard to assess the relative importance of the different climatic mechanisms that force glaciation across the himalayan tibetan orogen and to quantify paleoclimate change in this high altitude subtropical region the lateglacial and holocene glacial records however are particularly well preserved in several himalayan tibetan regions glacial successions such as these have the greatest potential to be examined in detail using newly developing numerical dating and geomorphic and sedimentologic methods to derive high resolution terrestrial records of glaciation that will help in paleoclimatic reconstruction for high altitude subtropical regions

geomorphological evidence of different glacial stages in the martial cirque fuegian andes southernmost south america abstract the geomorphological features of a cirque partially occupied by receding ice bodies are presented as evidences of different glacial stages in the fuegian andes summits since the last glaciation ios 2 a glacierization scheme involving i regional glacier accumulation basin ii glacier individualization from a main regional ii a stillstand during the general retreat and iii two advancing stages are suggested geomorphic and sedimentary units named martial i ii iii and iv have been distinguished as a consequence of the glacial scheme unfortunately the lack of datable materials has impeded establishment of an absolute chronology recognized glacier advances in the region are discussed the palaeoclimatic framework for the surroundings based on previous studies is presented

correlation of late quaternary moraines impact of climate variability glacier response and chronological resolution abstract the last decade has seen a global surge in the number and resolution of well dated geomorphological reconstructions of mountain glacier fluctuations and former ice sheet extents this has been facilitated by the widespread deployment of large samples of terrestrial cosmogenic nuclide dating tcnd allowing more sophisticated probability analyses for reducing the statistical uncertainty of moraine ages and testing of correlations at local regional and hemispheric scales geochronological advances in the field laboratory and on model calibration have taken place in parallel with modelling of palaeoclimate based on glacier reconstructions and of glacier sensitivity to temperature and precipitation forcing in spite of these advances basic conceptual issues remain this review questions whether the technical leap forward in dating has encouraged us to over reach our interpretive limits particularly in terms of the concept and practice of correlation we propose that to enable reliable correlation glacier chronologies should first be examined for their climatic integrity spatial coherence and chronological robustness even with excellent dating interpretive complexity remains due to complex climate signals and glacier response characteristics and to erosion censoring of the landform record all are issues which must be addressed to avoid either spurious lumping correlation or splitting differentiation of glacier chronologies and thus misinterpretation of the climatic significance of reconstructed glacier advances we suggest that the reliability of correlation is no better than the weakest link in the chain of reasoning which connects climatic fluctuations with dated landforms and sediments improved dating means that poor chronological resolution is less likely to be the limiting factor for correlation but shifts the focus onto other less quantifiable sources of uncertainty these conceptual statements are exemplified with reference to holocene glacial chronologies of contrasting mid latitude environments in southern norway iceland and new zealand

glacier readvances in the andes at 12 500 10 000 yr bp implications for mechanism of late glacial climatic change radiocarbon dates from two sites in the andes ecuador and peru confirm that glaciers culminated a readvance after 11 000 yr bp a moraine stage equivalent in altitude and position relative to existing glaciers is present in most glacierized ranges but its age is equivocal broadly limiting dates from colombia and peru suggest that the stage may be late glacial as it is younger than 12100 yr bp but formed before the early holocene in southern chile a comparable moraine stage is older than ca 9100 yr bp andean glaciers appear to have advanced at least twice during the late glacial interval glacier reconstruction from these moraine limits suggests depression of the equilibrium line altitude by at least 300 400 m in the northern and north central andes and possibly less than this farther south late glacial climatic change occurred globally and possibly reflects north atlantic temperature and circulation changes forced by deglaciation of the northern ice sheets migrations north and south of the atlantic polar front and the switching off and on of a dust pump in low midlatitudes

millennial scale climate changes on south georgia southern ocean abstract the location of south georgia 54 s 36 w makes it a suitable site for the study of the climatic connections between temperate and polar environments in the southern hemisphere because the mass balance of the small cirque glaciers on south georgia primarily responds to changes in summer temperature they can provide records of changes in the south atlantic ocean and atmospheric circulation we use grey scale density weight loss on ignition and grain size analyses to show that the proportion of glacially eroded sediments to organic sediments in block lake was highly variable during the last 7400 cal yr b p we expect that the glacial signal is clearly detectable above noise originating from nonglacial processes and assume that an increase in glacigenic sediment deposition in block lake has followed holocene glacier advances we interpret proglacial lake sediment sequences in terms of summer climate warming and cooling events prominent millennial scale features include cooling events between 7200 and 7000 5200 and 4400 and 2400 and 1600 cal yr b p and after 1000 cal yr b p comparison with other terrestrial and marine records reveals that the south georgian record captures all the important changes in southern hemisphere holocene climate our results reveal a tentative coupling between climate changes in the south atlantic and north atlantic because the documented temperature changes on south georgia are anti phased to those in the north atlantic

quaternary moraines vs catastrophic rock avalanches in the karakoram himalaya northern pakistan a history and conception of glacial events for the central karakoram himalaya proposed some 80 years ago by giotto dainelli are largely accepted today however certain deposits identified as terminal moraine complexes marking glacial episodes were actually emplaced by rock avalanches in the skardu and shigar intermontane basins of baltistan at least 15 rock avalanche events were previously mapped as moraine or till criteria used for distinguishing these catastrophic landslide deposits emphasize homogeneous lithology of rubble and matrix clast shape facies characteristics the large scale unity of emplacement and morphological relations to valley topography the deposits of three events at katzarah satpura and the north end of shigar valley have been reconstructed in detail thick supraglacial debris does not result in similar deposits extensive valley fills river terraces large sediment fans and lacustrine sediments formerly attributed to late glacial conditions are reinterpreted as postglacial events involving rock avalanches that interrupted fluvial development existing reconstructions of glaciations are left in doubt especially late glacial events in the central karakoram as are the roles assigned to karakoram main indus valley and western himalayan ice

dirt road a geomorphological and geochemical record of late holocene human activity in the catchment of lake radacz central pomerania poland abstract the paper offers a discussion of the record of human activity in the relief and sediments of a selected lake catchment in central pomerania in poland one of the basic markers of human activity here is a change in the lake water level the dropping level on average 1 m 100 years made it possible for people to develop successively exposed stretches of land along the shore an analysis of the polish national archeological records and archival maps showed that human development and impact appeared in the lakeshore zone as early as the neolithic in central pomerania the changes were especially intensive in the late holocene in the catchment of the lake under study they included a 100 increase in the length of nearby roads in the archives of its paleoenvironmental data most traces have been left on farming terraces while a poorly studied form of record of human activity is a dirt road running parallel to the shoreline geodetic and geochemical examination has revealed that the road is a stimulant of change its wheeled traffic mixes the accumulated and eroded material and this causes changes in the shoreline section the road cutting which is 2 m wide deepened while material accumulates in the form of 0 5 m wide lateral bars the compaction of the material brings about changes in the structure of the ground or soil its density porosity compactness moisture which affects its level of oxygenation and waterlogging and consequently its iron content to establish this a speciation analysis was carried out using the fe iii fe ii ratio it was determined that the lower the ratio the higher the susceptibility of land to deformation owing to an increase in soil density a drop in its water capacity reduction conditions and the predominance of fe ii the research discussed here is only a pilot study but the authors see extensive opportunities for using speciation analysis in geoarcheology

17 000 years of vegetation fire and climate change in the eastern foothills of the andes lat 44 s abstract paleoenvironmental records from patagonia reveal the importance of latitude longitude and elevation in shaping the response of vegetation to climate change we examined the vegetation fire and watershed history from two sites at lat 44 s as inferred from pollen charcoal and lithologic data these reconstructions were compared with independent paleoenvironmental records to better understand ecosystem dynamics along the southeastern andes lat 41 50 s our results show that at lat 44 s late glacial heath steppe was colonized by trees at 14 200 cal yr bp and forests became more closed at 11 500 cal yr bp differences in forest cover between the two sites were likely due to elevation dependent disparities in humidity and fire north of lat 44 s increasing precipitation favored initial forest development at 16 500 cal yr bp while dry conditions restricted tree expansion in the south until 7000 cal yr bp the time transgressive pattern is attributed to a gradual southward shift in the southern westerlies resulting from deglaciation and increasing annual insoltion present day vegetation developed at all latitudes during the middle to late holocene when the core of the southern westerlies reached its modern position 50 s asynchronous forest expansions north and south of lat 45 s between 5000 and 3000 cal yr bp are ascribed to centennial cycles of contraction and expansion of the southern westerlies which led to seasonal variations in precipitation at the core and northern border of the wind belt synchronous oscillations in tree abundance along the eastern andes prevailed during the last 3000 years decreased forest cover at all latitudes between 2500 and 1500 cal yr bp is concurrent with la nina like conditions and high solar irradiance these climate drivers likely decreased effective moisture and favored fires at all latitudes

the temporal significance of transitions from melting to calving termini at glaciers in the central southern alps of new zealand termini of valley glaciers in the central southern alps are undergoing a three phase sequence of retreat that began in the 1950s an initial phase of melting and slow downwasting under thickening supraglacial debris mantles is associated with stationary or slowly retreating termini this is followed by a transitional phase of disruption of insulating debris mantles allowing the rapid growth of shallow thermokarst lakes the shape and location of which vary according to glacier gradient and marginal topography a third phase of rapid calving retreat of ice cliffs into deepening proglacial lakes develops from the transitional phase at no stage are terminal responses simply related to climate present transitions to calving retreat are related to the morphology of glacier termini particularly to large outwash heads landform evidence indicates that similar calving phases do not appear to have occurred since late pleistocene deglaciation so that present changes to glacier termini are of great significance

three component sonde orientation in a deviated well in well seismics when operating with a three component tool particle velocities are measured in the sonde coordinate system but are often needed in other systems e g source bound or geographic when the well is vertical a change from the three orthogonal components of the sonde to another orthogonal coordinate system can be performed through one rotation around the vertical axis and if necessary another one around a horizontal axis hardage 1983 if the well is deviated the change of coordinate system remains easy in the case when the source is located at the vertical of the sonde or in the case when the source stands in the vertical plane defined by the local well axis in the general case offset vsps or walkaways or when looking for unknown sources such as microseismic emissions induced by hydraulic fracturing coordinate rotation may still be performed provided that we first get back to a situation in which one of the axes is vertical

a complex linear least squares method to derive relative and absolute orientations of seismic sensors summary determining the relative orientation of the horizontal components of seismic sensors is a common problem that limits data analysis and interpretation for several acquisition setups including linear arrays of geophones deployed in borehole installations or ocean bottom seismometers deployed at the seafloor to solve this problem we propose a new inversion method based on a complex linear algebra approach relative orientation angles are retrieved by minimizing in a least squares sense the l2 norm between the complex traces hodograms of adjacent pairs of sensors this methodology can be applied without restrictions only if the wavefield recorded by each pair of sensors is very similar in most cases it is possible to satisfy this condition by low pass filtering the recorded waveforms the main advantage of our methodology is that in the complex domain the relative orientations of seismic sensors can be viewed as a linear inverse problem which ensures that the preferred solution corresponds to the global minimum of a misfit function it is also possible to use simultaneously more than one independent data set other seismic events to better constrain the solution of the inverse problem furthermore by a computational point of view our method results faster than the relative orientation methods based on waveform cross correlation after several tests on synthetic data sets we applied successfully our methodology to different types of real data these applications include the alignment of borehole sensors relative to a vertical seismic profiling vsp acquisition and the orientation of ocean bottom seismometers obs relative to a neighbouring land station of known orientation using land stations the absolute orientation of obs can be retrieved finally as a last application we checked the correct orientation for land stations of a seismological array in germany

early and mid holocene age for the tempanos moraines laguna san rafael patagonian chile data about the nature and timing of holocene events from the southern hemisphere especially in southern south america are required to provide insight into the extent and nature of past climate change in a region where land based records are restricted here we present the first use of single grain optically stimulated luminescence osl dating of a moraine sequence recording glacial advance along the western side of the patagonian icefields dates from the tempanos moraines at laguna san rafael lsr show that the san rafael glacier srg advanced to maximum holocene positions during the period 9 3 to 9 7 ka and at 5 7 ka outwash lying beneath the moraine in its northern portion dated to 7 7 ka indicates that the glacier front was also advanced at this time since these advances span both the regional early holocene warm dry phase 11 5 ka to 7 8 ka and the subsequent cooling and rise in precipitation in the mid late holocene since 6 6 ka we infer that the advances of the srg are not simply climate driven but that the glacier has also probably responded strongly to non climatic stimuli such as internal ice dynamics and the transition between calving and non calving many westwards flowing glaciers in patagonia were probably calving during much of the late pleistocene and holocene so we conclude that establishing robust glacial chronologies where climatic and non climatic factors cannot be distinguished is likely to remain a challenge

a geochemical and sedimentary record of high southern latitude holocene climate evolution from lago fagnano tierra del fuego abstract situated at the southern margin of the hemispheric westerly wind belt and immediately north of the antarctic polar frontal zone tierra del fuego is well positioned to monitor coupled changes in the ocean atmosphere system of the high southern latitudes here we describe a holocene paleoclimate record from sediment cores obtained from lago fagnano a large lake in southern tierra del fuego at 55 s to investigate past changes in climate related to these two important features of the global climate system we use an ams radiocarbon chronology for the last 8000 yr based on pollen concentrates thereby avoiding contamination from bedrock derived lignite our chronology is consistent with a tephrochronologic age date for deposits from the middle holocene volcan hudson eruption combining bulk organic isotopic 13 c and 15 n and elemental c and n parameters with physical sediment properties allows us to better understand sediment provenance and transport mechanisms and to interpret holocene climate and tectonic change during the last 8000 yr co variability and long term trends in c n ratio carbon accumulation rate and magnetic susceptibility reflect an overall holocene increase in the delivery of terrestrial organic and lithogenic material to the deep eastern basin we attribute this variability to westerly wind derived precipitation increased wind strength and precipitation in the late holocene drives the nothofagus forest eastward and enhances run off and terrigenous inputs to the lake superimposed on the long term trend are a series of abrupt 9 negative departures in c n ratio which constrain the presence of seismically driven mass flow events in the record we identify an increase in bulk 13 c between 7000 and 5000 cal yr bp that we attribute to enhanced aquatic productivity driven by warmer summer temperatures the lago fagnano 13 c record shows similarities with holocene records of sea surface temperature from the mid latitude chilean continental shelf and antarctic air temperatures from the taylor dome ice core record in east antarctica mid holocene warming occurred simultaneously across the antarctic frontal zone and in particular in locations currently influenced by the antarctic circumpolar current

14c and 10be dated late holocene fluctuations of patagonian glaciers in torres del paine chile 51 s and connections to antarctic climate change abstract southern hemisphere holocene glacier chronologies are important for unraveling past climate change mid to high latitude teleconnections and regional to global climate forcing at present a significant number of glacier chronologies for patagonia are based on 14c dating which may afford only maximum or minimum limiting dates here we combine geomorphology and stratigraphy with radiocarbon 14c and beryllium 10 10be surface exposure age dating at three outlet glaciers zapata tyndall and pingo these glaciers drain the southernmost tip of the southern patagonian ice field at torres del paine national park chile 51 s after an expansion that we date at 3200 yr b p the torres del paine glaciers expanded to their last major late holocene maxima at 600 and 340 yr b p with the final dated readvance after 190 yr b p we use these data together with other patagonian glacier records to define the early mid and final glacial stages of the last millennium these cold events were separated by warm conditions that allowed the nothofagus forest to colonize deglaciated land the presence of near concurrent glacier fluctuations in patagonia and antarctic peninsula indicates widespread cooling punctuated the late holocene including the last millennium across much of the extratropical southern hemisphere we link this cooling to cold oceanographic atmospheric conditions forced by a northern shift or intensification of the southern westerly winds such scenario increased northward advection of cold antarctic circumpolar water along western patagonia and favored decreased upwelling of warm circumpolar deep water together with expanded sea ice around the antarctic peninsula

reconstruction of the late holocene paleoenvironment of the western beagle channel argentina based on a palynological analysis abstract palynological analysis was performed on sediment samples from arroyo baliza site 54 51 s 68 33 w western sector of the beagle channel tierra del fuego argentina in order to reconstruct the palaeoenvironmental history during the holocene marine transgressive regressive cycle in the beagle channel the palynological analysis reveals the presence of a closed canopy nothofagus forest development in the coastal areas under a cold wet and variable climate conditions during the late holocene the marine assemblage composition shows similarities to those modern assemblages recorded in the surface samples from the beagle channel characterised by the dominance of peridiniales taxa suggesting environmental conditions during the late holocene comparable to today the increasing salinity during middle holocene was accompanied by an increase in number and diversity of the microplanktonic assemblages suggesting the gradual installation of a marine environment as it exists today in the beagle channel

a 13 200 year history of century to millennial scale paleoenvironmental change magnetically recorded in the palmer deep western antarctic peninsula abstract a 13 200 yr record of magnetic parameters from the palmer deep western antarctic peninsula records a sequence of five distinct shifts in glacimarine sedimentation coupled with century scale variations in paleoproductivity the five major shifts are manifested as abrupt order of magnitude changes in low field magnetic susceptibility accompanied by changes in magnetic particle size and mineralogy the late holocene 3 4 0 ka the early holocene 11 5 9 ka and the last glacial maximum prior to 13 2 ka are intervals of strong low field magnetic susceptibility and are characterized by multi domain md magnetite md magnetite is associated with zones of abundant gravel grains and is interpreted here as an indicator of material transported as ice rafted debris deglaciation 13 2 11 5 ka and the middle holocene 9 3 4 ka were times of enhanced productivity the middle holocene marks the onset of century scale productivity cycles seen in high field magnetic susceptibility which is responding to variations in biogenic silica deglaciation and the middle holocene interval contain pseudo single domain magnetite and titanomagnetite respectively these observations are surprising given the abundance of coarse md magnetite available in local source rocks the magnetic mineral assemblage in the deglaciation interval however can be explained by density sorting in meltwater plumes during the middle holocene the magnetic mineral assemblage suggests the reduction or cessation of locally derived terrigenous sediment and by inference the reduction or cessation of iceberg generation the early holocene middle holocene shift in terrigenous sedimentation may be responding in part to sea level which controls the position of the grounding line the palmer deep late holocene interval coincides with the neoglacial period a time of glacier re advances worldwide

subdivision of holocene glacial deposits ben ohau range new zealand using relative dating methods relative dating methods measure post depositional alteration of surficial deposits measured in this study are the size of the yellow green rhizocarpon lichen percent lichen cover weathering rind thickness quartz vein height surface oxidation and pitting of clasts the data are used to subdivide holocene deposits in the ben ohau range and to suggest correlation with moraines in other parts of the southern alps glacial and or rock glacier deposits of five different ages are identified in the ben ohau range ages can be approximated mainly from the rind development curve of chinn 1981 from youngest to oldest the deposits are dun fiunary 100 yr whale stream 250 yr jacks stream 3 000 yr ferintosh 4 000 yr and birch hill 9 000 yr all but the whale stream have been previously named but data presented here result in improved definitions of mapping units and more accurate age assignment the present climate of the ben ohau range is increasingly continental to the south a similar climatic gradient existed for much of the post birch hill holocene as shown by the glacial depositional facies moraines are common to the north whereas rock glaciers especially of jacks stream and ferintosh ages are common to the south in some areas rock glaciers that have long been inactive have recently been reactivated data from moraines in the waimakariri drainage and the mount cook cameron valley and rakaia river areas improve previous correlations as relative dating methods provide age information where 14c ages are either lacking or limiting or when a single relative dating method is subject to erroneous interpretation

geophysical evidence of multiple glacier advances in lago fagnano 54 s southernmost patagonia the island of tierra del fuego at the southernmost extreme of patagonia is located in one of the most extensively glaciated areas of the southern hemisphere outside antarctica during the late pleistocene the lago fagnano region at w54 30 0 s and w68 w has experienced several phases of glacier growth and retreat since the last glacial maximum lgm we illustrate these phases using combined geomorphological geophysical and coring surveys in lago fagnano itself a w105 km long e w oriented glaciotectonic basin we identify and map a complex set of submerged frontal central and lateral moraines covered by lacustrine sediments using seismic stratigraphic analysis of multi channel profiles imaging the sub lake floor we then combine these geophysical data with field observations and regional maps of similar structures around the lake to reconstruct the spatial behavior of the fagnano paleo glacier since the lgm we interpret the preserved frontal moraines as having formed during at least 20 re advance stages of the glacier within a long term deglaciation interval post lgm preliminary tephrochronological dating of a w7 5 m long core indicates a step wise deglaciation pattern comprising a final glacier re advance stage at w11 2 ka bp

late glacial to holocene terrigenous sediment record in the northern patagonian margin paleoclimate implications abstract a high resolution study of clay mineralogy and major element geochemistry has been carried out on a high sedimentation rate deep sea core recovered off the taitao peninsula in southern chili 46 s to investigate climate and environmental changes in northern patagonia since the late glacial period the last 22 ka bp the chronology is based upon stable oxygen isotopes of planktonic foraminifera and ams radiocarbon dating smectite illite chlorite and ti k ratios reveal strong changes of the sedimentary sources between the crustal rocks of the coastal range and the volcanic rocks of the andean cordillera over the last 22 ka bp compared to the holocene the late glacial period was characterized by reduced input of detrital material derived from the high relief of the andean cordillera in agreement with a greater extension of the north patagonian ice cap that prevented chemical weathering of basalt smectite production and induced physical erosion of illite and chlorite from glacial scours the glacial period is also characterized by rapid changes of smectite illite chlorite and ti k ratios indicating short term centennial scale glacier fluctuations these changes could be the results of southern westerly shifts in the aysen region alternating periods when glaciers were probably less fed by precipitation mostly located in the north and consequently less active to ice accumulation periods the deglaciation was characterized by a trend towards warmer and more humid conditions punctuated by a cold and arid period partly coeval with the antarctic cold reversal event finally the holocene presents warmer and more humid conditions even though short term changes in the smectite illite chlorite ratio and the 18o record could be attributed to neoglacial events in the studied region

a new technique for identifying rock avalanche sourced sediment in moraines and some paleoclimatic implications moraine chronologies are widely used to infer local climate change events and to correlate these events globally based on the assumption that moraines always reflect climatic drivers however this assumption is unreliable in tectonically active terrain because moraines can also be formed by large landslide rock avalanche deposits on glaciers these can affect glacier motion and cause moraines to form while requiring no climate variation and can thus cause significant errors in climatic signals extracted from moraine chronologies to eliminate such errors requires a method for identifying moraines that have been influenced by rock avalanches herein we present and test a new diagnostic technique that unambiguously identifies rock avalanche sediments using newly discovered fine sediment signatures characteristic of rapid high stress comminution we test this technique on holocene moraines in the southern alps new zealand which have previously been interpreted as climatic indicators and demonstrate that some of them unambiguously contain rock avalanche material so their climatic significance is questionable

catastrophic landslides glacier behaviour and moraine formation a view from an active plate margin the influence of large bedrock landslides rock avalanches on the behaviour of glaciers is incompletely recognised here we present an example from an active tectonic margin in south island new zealand where large earthquakes leave a significant imprint on glacial records we demonstrate that terminal moraines on the western side of the southern alps record both ordinary i e climate driven and landslide initiated glacial advances following consideration of the processes involved in rock avalanche initiated moraine construction we suggest ways of determining the nature of the advance that built the terminal moraine the implications of these observations are important in breaking the conventional linkage of individual terminal moraines with climate forcing

freshwater calving and anomalous glacier oscillations recent behaviour of moreno and ameghino glaciers patagonia moreno glacier has been consistently advancing during a period of general glacier retreat this century and has repeatedly dammed an arm of lago argentino the most recent episode of ice dam failure and catastrophic lake drainage occurred in 1988 however the recent periodicity of this behaviour has now been interrupted and the current characteristics of the terminus suggest a future retreat because of the nature of calving dynamics such a retreat would be rapid and irreversible in the short term neighbouring ameghino glacier after almost a century of near stagnation commenced calving in a newly formed proglacial lake in about 1967 and then retreated 3 km at a mean rate of 334myr 1 for the next nine years in a fashion analagous to that predicted for moreno glacier the behaviour of these glaciers cannot be related directly to regional climate trends terminus response is more closely controlled by the interplay between calving dynamics and topography calving is therefore a potentially significant

holocene glacier variations in new zealand a review abstract in the central southern alps of new zealand ice surface lowering has exposed extensive sections of lateral moraines allowing investigation of moraine stratigraphy and genesis the presence of multiple superposed palaeosurfaces within moraine sequences allows recognition of any disturbances displacements or contamination of till layers and interbedded organic material radiocarbon dating of buried wood and soils allows comparison between the holocene glacial history of the eastern ranges and that of the westland region the periodicity of glacier response has been similar to both areas although the precise timing of events has differed due to local climatic and environmental factors in general glaciers in new zealand expanded about 5000 4500 4200 3700 3500 3000 2700 2200 1800 1700 1500 1100 900 700 600 and 400 100 bp

glacier fluctuations in extratropical south america during the past 1000 years article i nfo this paper presents an updated extensive review of glacier fluctuations during the past 1000 years in the extratropical andes of south america between ca 17 and 55 s given the variety of environmental conditions and evidence available for glacier fluctuations across this wide latitudinal range regional accounts are given for the desert andes 17 31 s the andes of central chile and argentina 31 36 s and the north 36 45 s and south 45 55 s patagonian andes the techniques dating limitations and interpretations of the glacier records along this transect are also discussed information on glacier fluctuations in the desert andes is limited to the 20th century documentation on past glacier variations is more abundant in the central chilean argentinean andes but the number of chronologies dealing with glacier fluctuations prior to the 1900s is also limited most records indicate that glaciers were generally more extensive prior to the 20th century with dates of maximum expansion ranging from the 16th to the 19th centuries the number and extent of glaciers increase significantly in the patagonian region where the evidence available for dating glacier variations during the past centuries is more abundant and the dating control for glacier events is generally better than in the northern parts of the study area for some patagonian glaciers maximum little ice age lia or post lia advances have been precisely dated by dendro geomorphological determinations or in situ measurements however for most sites the evidence available is still preliminary and there is considerable variability in the extent and timing of events related to the maximum lia expansion identified in most areas between the 16th and 19th centuries evidence is starting to appear at a growing number of sites for glacier advances during the first half of the past millennium these events were generally less extensive than the lia maximum pulses despite the occurrence of several post lia readvances over the past 100 110 years most areas in the andes of extratropical south america have experienced a general pattern of glacier recession and significant ice mass losses the differences in the glacier histories observed at local and regional scales probably reflect the inherent limitations associated with the glacier records and or the dating techniques used in each case together with the varying dominance of precipitation temperature and other climatic and non climatic factors on glacier mass balance and glacier dynamics these differences indicate that the late holocene glacier history of southern south america is more complex than commonly assumed the evidence discussed in this study highlights not only the immense potential for glaciological studies of this region but also a significant need for an increased number of detailed well dated records of glacier fluctuations

glaciation in the andes during the lateglacial and holocene this review updates the chronology of andean glaciation during the lateglacial and the holocene from the numerous articles and reviews published over the past three decades the andes which include some of the world s wettest and driest mountainous regions offer an unparalleled opportunity to elucidate spatial and temporal patterns of glaciation along a continuous 68 degree meridional transect the geographic and altitudinal extent of modern glaciers and the sensitivity of both modern and former glaciers to respond to changes in specific climatic variables reflect broad scale atmospheric circulation and consequent regional moisture patterns glaciers in the tropical andes and in the mid latitude andes are likely to have been far more sensitive to changes in temperature than glaciers in the dry subtropical andes broad scale temporal and spatial patterns of glaciation during the lateglacial are apparent in the southernmost andes the lateglacial chronology appears to have a strong antarctic signature with the best dated moraines correlating closely with the antarctic cold reversal the southernmost andes do not appear to have experienced a significant ice advance coeval with the younger dryas yd climatic reversal at the other end of the andes from w 0t o 9 n a stronger yd connection may exist but critical stratigraphic and geochronologic work is required before a yd ice advance can be fully demonstrated in the central andes of peru well dated moraines record a significant ice readvance at the onset of the yd but ice was retreating during much of the remaining yd interval the spatial temporal pattern of holocene glaciation exhibits tantalizing but incomplete evidence for an early to mid holocene ice advance s in many regions but not in the arid subtropical andes where moraines deposited during or slightly prior to the little ice age lia record the most extensive advance of the holocene in many regions there is strong evidence for neoglacial advances in the interval between 1 0 and 2 5 ka moraines that correlate with the lia of the northern hemisphere are seen in all presently glacierized mountain ranges most of these date to within the past 450 years outboard of these moraines in many regions are moraines of a slightly more extensive advance that occurred several hundred years prior to the onset of the lia priorities for future work include filling in several prominent spatial gaps in the distribution of chronologic studies for the lateglacial these gaps include the arid regions of northern chile and argentina the southern peruvian andes between 11 5 and 13 5 s and the andes of northern peru and

two methods for determining geophone orientations from vsp data vertical seismic profile vsp data are usually acquired with three component geophones of unknown azimuthal orientation the geophone orientation must be estimated from the recorded data as a prerequisite to processing such as p and s wave separation calculation of wave incident directions and 3d migration we compare and combine two methods for estimating azimuthal orientation by least squares fitting over a large number of shots combining the two methods can be done in an automated manner which provides more accurate estimates of the geophone orientations than previous methods in the polarization plane method we calculate the polarization plane of the first p wave arrival then we subtract the source azimuth to determine the geophone orientation independently for each geophone with an angular uncertainty of and with no accumulated errors in the relative angle method we obtain relative angles between adjacent geophone pairs using trace crosscorrelations and operate on all coherent signal

fluctuations of outlet and valley glaciers in the southern andes argentina during the past 13 000 years abstract in the southern argentine andes ten advances of valley glaciers were used to reconstruct the late glacial and holocene glacier history the accumulation areas of these glaciers lie in the precordillera and are thus independent of fluctuations of the south patagonian icefield like the viedma outlet glacier the valley glaciers advanced three times during late glacial time 14 000 10 000 yr b p the youngest advance correlates with the younger dryas stade based on two minimum ams 14 c dates of 9588 and 9482 yr b p the second oldest advance occurred before 11 800 yr b p during the first half of the holocene ca 10 000 5000 yr b p advances culminated about 8500 8000 7500 and 5800 5500 yr b p during the second half of the holocene advances occurred between ca 4500 and 4200 yr b p as well as between 3600 and 3300 yr b p in the rio condor valley three subsequent advances have been identified