natural magnetic disturbance fields not precursors preceding the loma prieta earthquake 1 available records of the magnetic indices dst and ap together with standard observatory recordings of 1 min field levels were examined for the period preceding the earthquake of october 1989 centered near loma prieta california the magnetic records showed that the fraser smith et al 1990 report claiming the existence of a 100 s ultralow frequency geomagnetic field precursor signal at corralitos california foretelling a nearby earthquake is not valid my study shows that the stanford ulf signal was not local but rather widespread throughout the western united states and therefore expected to be due to a coincidental geomagnetic solar terrestrial disturbance field

interhemispheric climate links revealed by a late glacial cooling episode in southern chile understanding the relative timings of climate events in the northern and southern hemispheres is a prerequisite for determining the causes of abrupt climate changes but climate records from the patagonian andes1 2 3 4 and new zealand5 6 7 8 for the period of transition from glacial to interglacial conditions about 14 6 10 kyr before present as determined by radiocarbon dating show varying degrees of correlation with similar records from the northern hemisphere it is necessary to resolve these apparent discrepancies in order to be able to assess the relative roles of northern hemisphere ice sheets and oceanic atmospheric and astronomical influences in initiating climate change in the late glacial period here we report pollen records from three sites in the lake district of southern chile 41 s from which we infer conditions similar to modern climate between about 13 and 12 2 14c kyr before present bp followed by cooling events at about 12 2 and 11 4 14c kyr bp and then by a warming at about 9 8 14c kyr bp these events were nearly synchronous with important palaeoclimate changes recorded in the north atlantic region9 supporting the idea that interhemispheric linkage through the atmosphere was the primary control on climate during the last deglaciation in other regions of the southern hemisphere where climate events are not in phase with those in the northern hemisphere local oceanic influences may have counteracted the effects that propagated through the atmosphere

the late crystallization stages of low ti low fe tholeiitic magmas insights from evolved antarctic and tasmanian rocks abstract examples of the latest stages of crystallization in evolved tholeiitic rocks can be found in the low ti low p ferrar magmatic province in antarctica e g thern promontory and archambault ridge and tasmania e g the red hill intrusion and mount wellington sill evolved rocks of this magmatic province include a rocks of basaltic andesite composition containing plagioclase augite pigeonite and interstitial fe ti oxides b rocks of andesitic composition with plagioclase as a liquidus phase a single fe rich subcalcic clinopyroxene and fe ti oxides and c rocks of dacitic composition displaying granophyric texture containing sodic plagioclase alkali feldspar ferrohedenbergite fayalite fe ti oxides quartz and accessory phases the latest crystallization stages are thus characterized by the striking chemical convergence of subcalcic fe augite and fe pigeonite followed by more evolved rocks that preserve quartz alkali feldspar cotectic granophyric relationships lack subcalcic clinopyroxene and contain coexisting olivine and calcium rich clinopyroxene these features are consistent with crystallization at or below the quartz fayalite magnetite oxygen buffer at temperatures close to 800 c the trace element geochemistry of coexisting pyroxenes feldspar and fe ti oxides are entirely consistent with magmatic evolution caused by fractional crystallization of the observed phases similarities and differences with other silicic volcanic rocks elsewhere are also described there is no evidence for liquid immiscibility

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

crystallization experiments on a gusev adirondack basalt composition until recently the snc meteorites represented the only source of information about the chemistry and petrology of the martian surface and mantle the mars exploration rovers have now analyzed rocks on the martian surface giving additional insight into the petrology and geochemistry of the planet the adirondack basalts analyzed by the mer spirit in gusev crater are olivine phyric basaltic rocks which have been suggested to represent liquids and might therefore provide new insights into the chemistry of the martian mantle experiments have been conducted on a synthetic humphrey composition at upper mantle and crustal conditions to investigate whether this composition might represent a primary mantle derived melt the humphrey composition is multiply saturated at 12 5 kbar and 1375 c with olivine and pigeonite a primary anhydrous melt derived from a chondritic mantle would be expected to be saturated in orthopyroxene not pigeonite in addition the olivine and pigeonite present at the multiple saturation are too ferroan to have been from a martian mantle as is understood now therefore it seems likely that the humphrey composition does not represent a primary anhydrous melt from the martian mantle but was affected by mineral melt fractionations at lower crustal pressures

holocene rainfall variability in southern chile a marine record of latitudinal shifts of the southern westerlies geochemical and clay mineral parameters of a high accumulation marine sediment core from the chilean continental slope 41 s provide a 7700 yr record of rainfall variability in southern chile related to the position of the southern westerlies we especially use the iron content measured with a time resolution of ca 10 yr on average of 14 caccelerator mass spectrometry dated marine sediments as a proxy for the relative input of iron poor coastal range and iron rich andean source rocks variations in this input are most likely induced by rainfall changes in the continental hinterland of the core position based on these interpretations we find a pronounced rainfall variability on multicentennial to millennial time scales superimposed on generally more arid conditions during the middle holocene 7700 to 4000 cal yr b p compared to the late holocene 4000 to present this variability and thus changes in the position of the southern westerlies are first compared to regional terrestrial paleoclimate data sets from central and southern chile in order to derive possible wider implications and forcing mechanisms of the holocene latitudinal shifts of the southern westerlies we then compare our data to ice core records from both tropical south america and coastal antarctica these records show similar bands of variability centered at ca 900 and 1500 yr comparisons of band pass filters suggest a close connection of shifts of the southern westerlies to changes within the tropical climate system the correlation to climate conditions in coastal antarctica shows a more complicated picture with a phase shift at the beginning of the late holocene coinciding with the onset of the modern state of el nin o southern oscillation system the presented data provide further evidence that the well known millennial scale climate variability during the last glacial continued throughout the holocene fl 2001 elsevier science b v all rights reserved

on the ulf magnetic ratio increase before the 2008 iwate miyagi nairiku earthquake by hirano and hattori 2011 abstract hirano and hattori 2011 hereafter cited as h h report the observation of anomalous increases in the ulf geomagnetic field spectral density ratio which the authors claim to be possible precursors of the 2008 iwate miyagi nairiku earthquake here the results of h h are reviewed taking into account the global geomagnetic activity level by means of k p index this paper cast serious doubts on the seismogenic origin of the magnetic signatures documented by h h showing that the anomalous signals are normal ulf magnetic variations induced by solar terrestrial interaction in summary h h s claims that magnetic field disturbances about a month before the mw 6 9 iwate miyagi nairiku earthquake on june 13 2008 are precursors to the earthquake are unlikely to be correct

comment on glacial geomorphology and chronology of deglaciation south georgia sub antarctic by m j bentley d j a evans c j fogwill j d hansom d e sugden p w kubik

are there new findings in the search for ulf magnetic precursors to earthquakes moore 1964 in a letter published in nature reported disturbances in geomagnetic field data prior to the 27 march 1964 alaska earthquake after the publication of this report many papers have shown magnetic changes preceding earthquakes however a causal relationship between preearthquake magnetic changes and impending earthquakes has never been demonstrated as a consequence after 50 years magnetic disturbances in the geomagnetic field are still candidate precursory phenomena some researchers consider the investigation of ultra low frequency ulf 0 001 10 hz magnetic data the correct approach for identifying precursory signatures of earthquakes other researchers instead have recently reviewed many published ulf magnetic changes that preceded earthquakes and have shown that these are not actual precursors the recent studies by currie and waters 2014 and han et al 2014 aim to provide relevant new findings in the search for ulf magnetic precursory signals however in order to contribute to science alleged precursors must be shown to be valid and reproducible by objective testing here we will briefly discuss the state of the art in the search for ulf magnetic precursors paying special attention to the recent findings of currie and waters 2014 and han et al 2014 we do not see in these two reports significant evidence that may support the observation of precursory signatures of earthquakes in ulf magnetic records

peat bank growth holocene palaeoecology and climate history of south georgia sub antarctica based on a botanical macrofossil record botanical macrofassil analysis of a more than 9000 years old radiocarbon dated peat sequence of a moss peat bank from south georgia shows a clear evolution in the vegetation seven ecological phases could be distinguished and they can be interpreted in terms of climate development during the holocene until 2200 years ago warnstorfia fontinatiopsis was the dominant moss species pointing to a wet environment lower numbers of this species in association with the presence of drier species are assumed to indicate drier periods such as occurring between ca 6000 5200 and 4400 3400 cal yr br the most prominent and definitive vegetation change took place around 2200 cal yr bp a polytilchum chollsodontium moss peat bank was formed which is still growing there today the forcing mechanism for this vegetation change is thought to be a temperature decrease rather than a precipitation decrease this conclusion is mainly based on the fact that today moss peat banks have their optimal occurrence range in the maritime antarctic a region were the mean annual temperature is ca 4 degrees c lower than on south georgia the remarkable change in the moss bank vegetation at 2200 cal yr bp raises the question whether this moment was only a short climatic deterioration or a definitive change to a cooler and wetter climate after a holocene climatic optimum period c 2008 elsevier ltd all rights reserved

oceanic forcing of ice sheet retreat west antarctica and more ocean ice interactions have exerted primary control on the antarctic ice sheet and parts of the greenland ice sheet and will continue to do so in the near future especially through melting of ice shelves and calving cliffs retreat in response to increasing marine melting typically exhibits threshold behavior with little change for forcing below the threshold but a rapid possibly delayed shift to a reduced state once the threshold is exceeded for thwaites glacier west antarctica the threshold may already have been exceeded although rapid change may be delayed by centuries and the reduced state will likely involve loss of most of the west antarctic ice sheet causing 3 m of sea level rise because of shortcomings in physical understanding and available data uncertainty persists about this threshold and the subsequent rate of change although sea level histories and physical understanding allow the possibility that ice sheet response could be quite fast no strong constraints are yet available on

on claimed ulf seismogenic fractal signatures in the geomagnetic field 1 during the last ten years fractal analysis of ultra low frequency ulf geomagnetic field components has been proposed as one of the most promising tools to highlight magnetic precursory signals possibly generated by the preparation processes of earthquakes several papers claim seismogenic changes in the fractal features of the geomagnetic field some months before earthquakes occur the target of the present paper is to put forth a qualitative investigation on the fractal characteristics of ulf magnetic signatures that previous authors have claimed to be related without doubt to strong earthquakes this analysis takes into account both the temporal evolution of the geomagnetic field fractal parameters reported in previous researches and the temporal evolution of global geomagnetic activity running averages of the geomagnetic indices kp and ap are plotted into the original figures from the previous publications this simple analysis shows that the fractal features of the ulf geomagnetic field are closely related to the geomagnetic activity both before and after the earthquake occurs the correlation between the geomagnetic field fractal parameters and geomagnetic activity is clearly shown over both long and short time scales in light of this the present paper shows that fractal behaviors of previously claimed seismogenic ulf magnetic signatures depend mainly on geomagnetic activity due to solar terrestrial interaction therefore previously reported association with the preparation process of the earthquake is dubious

estimating the lunar mantle water budget from phosphates complications associated with silicate liquid immiscibility abstract the discovery of water within the lunar mantle has broad implications for the formation of the earth moon system differentiation of the moon and the magmatic evolution of lunar basalts as well as the highland rocks recently there has been considerable interest in using combined water abundances and h isotope systematics of lunar apatites from mare basalts to quantify the origin and extent of water within the moon s mantle however the petrologic and geochemical conditions that govern apatite crystallization are not well constrained especially for high feo basaltic melts that crystallize at fo2 values below the iron wustite buffer apatites are typically located within the late stage interstitial regions in this contribution we present detailed textural descriptions of late stage inter cumulus residual liquid pockets i e mesostasis pockets in order to understand the petrogenesis of lunar apatite results from five mare basalts demonstrate that the majority of the residual liquids in mesostasis regions have undergone silicate liquid immiscibility sli splitting into si k rich felsic and fe rich fe basaltic conjugate liquids we demonstrate the complexity of these residual liquids by documenting a wide range of water contents for apatites in several mesostasis pockets within a single mare basalt a complexity common to many basalts these data illustrate that individual apatite hosting mesostasis pockets behave as independent sub systems even within a single rock furthermore we present water concentrations for another phosphate phase merrillite indicating additional uncertainties during considerations of water partitioning into apatite fractional crystallization trends have been used in order to assess the conditions under which magmas are likely to undergo sli predicted liquid lines of descent indicate that it is the late stage residual liquids of lunar basalts with relatively low mg e g 50 may not intersect the two liquid field depending upon the fractionation trends in the late stage mesostasis pockets for samples that undergo sli the apatite melt partition coefficients required for back calculating water abundances of the parental melts are compromised by the generation of two populations of apatites merrillites from conjugate immiscible liquids this process highlights an important complexity inherent to all water back calculations that use apatite as this requires an additional set of partition coefficients we emphasize that the complex petrologic nature and common development of sli of apatite bearing late stage mesostasis pockets have not been considered in published apatite volatile data these factors in additional to other considerations illustrate why water back calculations to model the primary melts from such data must be viewed with caution

the magnitude and rapidity of the climate change marking the end of the pleistocene in the mid latitudes of south america abstract the chi squared test of independence and cluster analysis of otsuka similarity coefficients of fossil beetle assemblages from the chilean lake region in the mid latitudes of south america support the following conclusions 1 the mean summer temperature of the glacial climate was 4 5 c lower than today s climate 2 the climatic change from glacial to interglacial mode was in a single step centered on about 14 000 yr b p 3 the climatic change was rapid and within 1500 years the biota of a moorland had been completely replaced by a biota of a rain forest 4 by 12 500 yr b p the low elevation beetle fauna of the chilean lake region was similar in composition to that of the present day and 5 no reversal in the postglacial warming trend equivalent in age to the younger dryas stade was detected

mid holocene erosion of soil catenas on moraines near the type pinedale till wind river range wyoming abstract buried soils are described from the floors of four kettles on pinedale piedmont moraines of the southwestern wind river range wyoming near the type locality of the pinedale till the buried soils indicate that a previously unreported episode of slope erosion has occurred along adjacent catenas on some of the moraines in this region radiocarbon ages of the buried soils indicate that slope erosion occurred during the middle holocene from 8540 190 to 4800 60 14c yr b p the presence of buried soils in moraine kettles indicates that profiles on the crests and backslopes of some of the moraines in this region are not the products of continuous post pinedale soil formation rather the crest and backslope soils on pinedale moraines result from two periods of soil development separated by an interval of erosion thus soils on crests and backslopes are considered to be welded profiles relative age studies that use soil data to estimate the age of moraines in this region must take into account the possibility that a mid holocene erosion episode affected the genesis and morphology of soils on the moraines this study corroborates results of previous work that suggests that data from complete catenas are more useful for estimating the characteristic soil development on quaternary moraines than are data derived from crests alone

on the seismogenic increase of the ratio of the ulf geomagnetic field components abstract following the paper by fraser smith et al 1990 many scientists have focused their research on the ulf geomagnetic field pulsations in the hope of finding possible anomalous signals caused by the seismic activity thereafter many papers have reported ulf geomagnetic field polarization ratio increases which have been claimed to be related to the occurrence of moderate and strong earthquakes even if there is no firm evidence of correlation between the polarization ratio increase and seismic events these publications maintain that these anomalous increases are without doubt precursors of pending earthquakes furthermore several researchers suggest that these seismogenic signals may be considered a promising approach towards the possibility of developing short term earthquake prediction capabilities based on electromagnetic precursory signatures on the contrary a part of the scientific community emphasizes the lack of validation of claimed seismogenic anomalies and doubt their association with the seismic activity since earthquake prediction is a very important topic of social importance the authenticity of earthquake precursors needs to be carefully checked the aim of this paper is to investigate the reliability of the ulf magnetic polarization ratio changes as an earthquakes precursor several polarization ratio increases of the geomagnetic field which previous researchers have claimed to have a seismogenic origin are put into question by a qualitative investigation the analysis takes into account both the temporal evolution of the geomagnetic field polarization ratio reported in previous papers and the global geomagnetic activity behaviour running averages of the geomagnetic index k p are plotted onto the original figures from previous publications moreover further quantitative analyses are also reported here nine cases are investigated which include 17 earthquakes in seven cases it is shown that the suggested association between the geomagnetic field polarization ratio increases and the earthquake preparation process seems to be rather doubtful more precisely the claimed seismogenic polarization ratio increases are actually closely related to decreases in the geomagnetic activity level furthermore the last two investigated cases seem to be doubtful as well although a close correspondence between polarization ratio and geomagnetic activity cannot be unambiguously demonstrated

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

340 000 year centennial scale marine record of southern hemisphere climatic oscillation in order to investigate rapid climatic changes at mid southern latitudes we have developed centennial scale paleoceanographic records from the southwest pacific that enable detailed comparison with antarctic ice core records these records suggest close coupling of mid southern latitudes with antarctic climate during deglacial and interglacial periods glacial sections display higher variability than is seen in antarctic ice cores which implies climatic decoupling between mid and high southern latitudes due to enhanced circum antarctic circulation structural and temporal similarity with the greenland ice core record is evident in glacial sections and suggests a degree of interhemispheric synchroneity not predicted from bipolar ice core correlations

on the reported magnetic precursor of the 1993 guam earthquake 1 using 1 second magnetometer data recorded 67 km from the epicenter of the 1993 mw 7 7 guam earthquake hayakawa et al 1996 and miyahara et al 1999 identify anomalous precursory changes in ultra low frequency magnetic polarization the ratio of vertical to horizontal field components in a check of their results we compare their data gam with 1 second data from the kakioka observatory kak in japan and the global magnetic activity index kp we also examine log books kept by usgs staff working on the guam magnetic observatory we find 1 analysis problems with both hayakawa et al and miyahara et al 2 significant correlation between the gam kak and kp data and 3 an absence of identifiable localized anomalous signals occurring prior to the earthquake the changes we do find in polarization are part of normal global magnetic activity they are unrelated to the earthquake

holocene glacier fluctuations a global overview of glacier advances and retreats grouped by regions and by millennia for the holocene is compiled from previous studies the reconstructions of glacier fluctuations are based on 1 mapping and dating moraines defined by 14 c tcn osl lichenometry and tree rings discontinuous records time series and 2 sediments from proglacial lakes and speleothems continuous records time series using 189 continuous and discontinuous time series the long term trends and centennial fluctuations of glaciers were compared to trends in the recession of northern and mountain tree lines and with orbital solar and volcanic studies to examine the likely forcing factors that drove the changes recorded a general trend of increasing glacier size from the earlyemid holocene to the late holocene in the extra tropical areas of the northern hemisphere nh is related to overall summer temperature forced by orbitally controlled insolation the glaciers in new zealand and in the tropical andes also appear to follow the orbital trend i e they were decreasing from the early holocene to the present in contrast glacier fluctuations in some monsoonal areas of asia and southern south america generally did not follow the orbital trends but fluctuated at a higher frequency possibly triggered by distinct teleconnections patterns during the neoglacial advances clustered at 4 4e4 2 ka 3 8e3 4 ka 3 3e2 8 ka 2 6 ka 2 3e2 1 ka 1 5e1 4 ka 1 2e1 0 ka 0 7e0 5 ka corresponding to general cooling periods in the north atlantic some of these episodes coincide with multidecadal periods of low solar activity but it is unclear what mechanism might link small changes in irradiance to widespread glacier fluctuations explosive volcanism may have played a role in some periods of glacier advances such as around 1 7e1 6 ka coinciding with the taupo volcanic eruption at 232 5 ce but the record of explosive volcanism is poorly known through the holocene the compilation of ages suggests that there is no single mechanism driving glacier fluctuations on a global scale multidecadal variations of solar and volcanic activity supported by positive feedbacks in the climate system may have played a critical role in holocene glaciation but further research on such linkages is needed the rate and the global character of glacier retreat in the 20th through early 21st centuries appears unusual in the context of holocene glaciation though the retreating glaciers in most parts of the northern hemisphere are still larger today than they were in the early and or mid holocene the current retreat

large silica rich igneous textured inclusions in the buzzard coulee chondrite condensates differentiates or impact melts we studied three large 2 4 mm diameter igneous textured inclusions in the buzzard coulee h4 chondrite using microanalytical techniques olm sem empa sims to better elucidate the origins of igneous inclusions in ordinary chondrites the inclusions are clasts that come in two varieties 1 white inclusions bz 1 and bz 2 represent a nearly holocrystalline assemblage of low ca and high ca pyroxene 63 66 area and cristobalite 33 36 and 2 tan inclusion bz 3 is glass rich approximately 60 with low ca and high ca pyroxene phenocrysts the bulk compositions of the inclusions determined by modal reconstruction are all sio2 rich approximately 67 wt for bz 1 and bz 2 approximately 62 for bz 3 but bz 3 is enriched in incompatible elements e g ree approximately 4 5 ci abundances whereas bz 2 and bz 1 are depleted in those elements that are most incompatible in pyroxene e g la ho approximately 0 15 0 4 ci abundances these bulk compositions do not resemble what one would expect for partial or complete shock melting of a chondritic precursor and show no evidence for overall volatility control we infer that the inclusions originated through igneous differentiation and feo reduction with bz 3 forming as an andesitic partial melt approximately 30 40 partial melting of an h chondrite precursor and bz 1 and bz 2 forming as pyroxene cristobalite cumulates from an si rich melt we suggest that both types of melts experienced a period of transit through a cold low pressure space environment in which cooling feo reduction and interaction with a vapor occurred melts may have been lofted into space by excavation or splashing during collisions or by pyroclastic volcanism our results indicate intriguing similarities between the inclusions in buzzard coulee and the silicates in some iron iie type and stony iron iva type meteorites suggesting a genetic relationship

ice caps existed throughout the lateglacial interstadial in northern scotland we constrain in detail fluctuations of two former ice caps in nw scotland with multibeam seabed surveys geomorphological mapping and cosmogenic 10 be isotope analyses we map a continuous sequence of 40 recessional moraines stretching from 10 km offshore to the wester ross mountains surface exposure ages from boulders on moraine ridges in assynt and the summer isles region show that substantial dynamic ice caps existed in nw scotland between 13 and 14 ka bp we interpret this as strong evidence that large active glaciers probably survived throughout the lateglacial interstadial and that during the older dryas period ca 14 ka bp ice caps in nw scotland were thicker and considerably more extensive than in the subsequent younger dryas stadial by inference we suggest that lateglacial ice cap oscillations in scotland reflect the complex interplay between changing temperature and precipitation regimes during this climatically unstable period ca 15 11 ka bp natural environment research council nerc copyright 2008 reproduced with the permission of nerc published by john wiley sons ltd

palaeoenvironmental and stratigraphic significance of the valley farm and barham soils in eastern england abstract the valley farm and barham soils are important stratigraphic units representing an early and or middle pleistocene depositional hiatus within parts of eastern england the barham soil buried beneath anglian sediments is recognised by a variety of large and small scale cryogenic features which developed in cromerian sediments or were superimposed upon the valley farm soil during the early anglian the valley farm soil is rubified mottled and contains substantial quantities of translocated clay originally attributed solely to temperate cromerian stage pedogenesis its stratigraphic status has changed over recent years as the age range of its kesgrave sands and gravels parent material has been extended currently the valley farm soil is regarded as a complex stratigraphic unit with component soils developed on a series of different age surfaces perhaps spanning cold and temperate intervals over more than a million years detailed micromorphological studies of the valley farm soil on some of these surfaces have confirmed its variable pedological complexity a number of theoretical and practical problems however need to be confronted and solved before its pedological record can be used routinely to provide an independent means of dating and reconstructing detailed palaeoenvironments

future directions of paleoclimate research abstract this viewpoint identifies two issues seen by the author as critical for future paleoclimate research i the nature and cause of climatic conditions during peak glacial times ii the geographic pattern of abrupt changes of climate and the factors that initiated these changes a list of research programmes designed to test these issues is given

divergent trends in land and ocean temperature in the southern ocean over the past 18 000 years reconstructions of land and ocean temperatures over the past 18 000 years in the high southern latitudes have shown conflicting trends analyses of temperatures on campbell island south of new zealand confirm this behaviour and lead to the suggestion that it reflects changes in the position and intensity of the westerly winds over the past 18 000 years sea surface temperatures for the southern ocean do not align with those of the adjacent high latitude landmasses during the late glacial period the ocean surface warmed rapidly to present day temperatures1 whereas the land warmed only slowly as evidenced by the lagged response of forest and glaciers2 3 however in the holocene epoch land based records suggest strong warming whereas marine records indicate that ocean surface temperatures cooled here we present reconstructions of summer temperature for campbell island in the southern ocean over the past 16 500 years based on fossil pollen we find a pronounced warming 12 500 11 000 years ago a cooling until 9 200 years ago and a rapid warming to a peak between 6 000 and 5 000 years ago followed by minor cool intervals from 5 200 4 000 3 000 1 700 and 700 100 years ago as expected our temperature reconstructions show a late glacial lag behind nearby records of sea surface temperature6 7 and opposing trends in the holocene we suggest that this discrepancy arises because land based reconstructions record summer temperatures whereas marine proxies generally reflect annual temperatures we conclude that the divergence of the records therefore reflects changes in the seasonality of atmospheric heat transport as atmospheric heat transport is tied to the southern hemisphere westerly winds we attribute our observed changes to shifts in the position and intensity of the southern westerlies

eight glacial cycles from an antarctic ice core the antarctic vostok ice core provided compelling evidence of the nature of climate and of climate feedbacks over the past 420 000 years marine records suggest that the amplitude of climate variability was smaller before that time but such records are often poorly resolved moreover it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records here we report the recovery of a deep ice core from dome c antarctica that provides a climate record for the past 740 000 years for the four most recent glacial cycles the data agree well with the record from vostok the earlier period between 740 000 and 430 000 years ago was characterized by less pronounced warmth in interglacial periods in antarctica but a higher proportion of each cycle was spent in the warm mode the transition from glacial to interglacial conditions about 430 000 years ago termination v resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases but there are significant differences in the patterns of change the interglacial stage following termination v was exceptionally long 28 000 years compared to for example the 12 000 years recorded so far in the present interglacial period given the similarities between this earlier warm period and today our results may imply that without human intervention a climate similar to the present one would extend well into the future

a fundamental dispute a discussion of on some fundamentals of igneous petrology by bruce d marsh contributions to mineralogy and petrology 2013 166 665 690 marsh contrib miner petrol 166 665 690 2013 again claims that crystal free basalt magmas are unable to differentiate in crustal magma chambers and regards layered intrusions as primarily due to the repeated emplacement of crystal suspensions he ignores an earlier critique of his unconventional inferences latypov j petrol 50 1047 1069 2009 as well as a wealth of petrographic geochemical and experimental evidence supporting the dominant role of fractional crystallization in the solidification of layered intrusions most tellingly the cryptic variations preserved in the skaergaard and many other basaltic layered intrusions would require an exceedingly implausible sequence of phenocrystic magmas but are wholly consistent with in situ fractional crystallization a major flaw in marsh s hypothesis is that it dismisses progressive fractional crystallization within any magma chamber and hence prohibits the formation of crystal slurries with phenocrysts and melts that change systematically in composition in any feeder system this inherent attribute of the hypothesis excludes the formation of layered intrusions anywhere

fractal analysis of ulf geomagnetic data associated with the guam earthquake on august 8 1993 this paper presents a fractal analysis of the ulf electromagnetic data obtained at guam observatory during a strong ms 8 0 earthquake occurred on august 8 1993 near the guam island we have already reported the presence of seismogenic ulf emissions for this quake hayakawa et al grl 1996 the chosen period covered four months before and two months after the earthquake it was found that the spectrum of emissions at noon exhibited a power law behavior f which is typical for self organized critical dynamics the slope of the spectrum in the noon sector fluctuates in a range from 2 5 to 0 7 with a tendency to gradually decrease during the process of the earthquake preparation we consider this to be a candidate for a precursory signature the similar effect was found for the night sector we suggest that the focal zone was at the critical stage of self organized criticality process before the quake related to active microfracturing processes followed by the generation of ulf emissions as we detected

glacial history of sub antarctic south georgia based on the submarine geomorphology of its fjords we present multibeam swath bathymetric surveys of the major fjords surrounding the sub antarctic island of south georgia to characterise the glacial geomorphology and to identify the relative timings and extent of past glacial advance and retreat bathymetry data revealed a range of glacial features including terminal retreat and truncated moraines deep distal outer and shallow proximal inner basins and cross shelf troughs these provide evidence of glacial advance and retreat through several glacial cycles a near consistent pattern of large scale submarine geomorphological features was observed in the different fjords suggesting a similar response of margins of the island ice cap to past climate forcing a relative chronology based on the relationships between the submarine features with their radiocarbon and cosmogenic isotope dated terrestrial counterparts suggests that widely observed inner basin moraines date from the last major glacial advance or last glacial maximum while deep basin moraines may date from an earlier pre lgm more extensive glaciation which we speculate corresponds to mis6 on the sides of the deep basins a series of truncated moraines show ice advance positions from preceding glacial periods the cross shelf troughs and mid trough moraines are interpreted as the product of much more extensive glaciations that predate the fjord geomorphology mapped here thus possibly older than mis6 this hypothesis would suggest that south georgia followed a glacial history similar to that of central patagonia 46 s where a series of pleistocene glaciations of mis 20 and younger extended beyond lgm limits with the most extensive glacial advance occurring at c 1 1 ma

glacial geomorphology and chronology of deglaciation south georgia sub antarctic we mapped and dated the glacial geomorphology of north east south georgia in the maritime sub antarctic the aim was to examine the timing of deglaciation of the island in the context of inter hemispheric phasing of climate change former glacier limits are restricted to the inner fjords and our detailed mapping of them has demonstrated a consistent geomorphological pattern that is similar across several different glacier types and sizes the pattern comprises three suites of moraines categories a c not all of which are represented at every site because the outer suite is often overridden by younger suites category a is an outer wide low amplitude moraine ridge category b comprises 2 4 sharp crested bouldery moraines that are often located close to or even over riding a and category c is a series of lower amplitude moraines with overprinted streamlined landforms such as flutings analysis of in situ cosmogenic 10be in boulders on these moraines has allowed us to determine a deglacial chronology for the older two moraine groups the age of the inner youngest group has been estimated from soil development the cosmogenic nuclide ages show that the outermost moraine was deposited ca 12 2 1 5 ka bp but that a subsequent readvance in the mid holocene ca 3 6 1 1 ka bp reached and in places over rode this earlier moraine this latter advance coincides with the mid holocene hypsithermal a final late holocene advance reached closely similar limits to the previous two fluctuations and is estimated from soil data to have an age of ca 1 1 ka bp we suggest that the close concordance of late glacial and interglacial limits in this case associated with warming can be explained by a change in dominant forcing during glacials extensive sea ice limits precipitation availability and so glaciers are restricted to the inner fjords during interglacials precipitation is not limited in the same way by sea ice cover and so during warming precipitation increases and tidewater glaciers on the island have responded by advancing this study emphasises the importance of a clear understanding of geomorphology in order to interpret chronological information

holocene environmental change in south georgia evidence from lake sediments the holocene environmental history of south georgia is important because of the island s location in the southern westerlies in an oceanic zone of the world devoid of high resolution terrestrial records this is the first attempt to interpret a palaeoenvironmental record from lake sediments in south georgia it is based on a wide variety of analyses undertaken on cores from two lakes both are in the same unglaciated drainage basin but one is at 80 m above sea level and near the altitudinal limit for vegetation growth whereas the other is at 25 m and within the zone of continuous vegetation cover results from both lakes indicate shifts of vegetation boundaries which together with evidence for changing biotic productivity within the lakes themselves are interpreted as indicating climatic changes radiocarbon dates on the main changes identify a climatic optimum beginning before 5620 290 14c yr bp and ending at around 4815 330 14c yr bp when conditions in the upper part of the catchment were more conducive to plant growth than they are today the record obtained from the lower lake was shorter but indicates two periods of harsher climate relative to the present since 4000 yr bp this interpretation of the lake evidence agrees with other dated evidence of environmental change from peat sections glacial stratigraphy and geomorphology in south georgia together the work allows an overall reconstruction of environmental change in the holocene

late holocene glacial advance and ice shelf growth in barilari bay graham land west antarctic peninsula three marine sediment cores were collected along the length of the fjord axis of barilari bay graham land west antarctic peninsula 65 55 s 64 43 w multi proxy analytical results constrained by high resolution geochronological methods 210 pb radiocarbon 137 cs in concert with historical observations capture a record of holocene paleoenvironmental variability our results suggest early and middle holocene 7022 2815 cal calibrated yr b p retreated glacial positions and seasonally open marine conditions with increased primary productivity climatic cooling increased sea ice coverage and decreased primary productivity during the neoglacial 2815 to cal 730 cal yr b p this climatic cooling culminated with glacial advance to maximum holocene positions and expansion of a fjord wide ice shelf during the little ice age lia ca 730 82 cal yr b p seasonally open marine conditions were achieved and remnant ice shelves decayed within the context of recent rapid regional warming 82 cal yr b p to present our findings agree with previously observed late holocene cooling and glacial advance across the antarctic peninsula suggesting that the lia was a regionally significant event with few disparities in timing and magnitude comparison of the lia antarctic peninsula record to the rest of the southern hemisphere demonstrates close synchronicity in the southeast pacific and southern most atlantic region but less coherence for the southwest pacific and indian oceans comparisons with the northern hemisphere demonstrate that the lia antarctic peninsula record was contemporaneous with pre lia cooling and sea ice expansion in the north atlantic arctic suggesting a global reach for these events

origin and chronology of chondritic components a review abstract mineralogical observations chemical and oxygen isotope compositions absolute 207pb 206pb ages and short lived isotope systematics 7be 7li 10be 10b 26al 26mg 36cl 36s 41ca 41k 53mn 53cr 60fe 60ni 182hf 182w of refractory inclusions ca al rich inclusions cais and amoeboid olivine aggregates aoas chondrules and matrices from primitive unmetamorphosed chondrites are reviewed in an attempt to test i the x wind model vs the shock wave model of the origin of chondritic components and ii irradiation vs stellar origin of short lived radionuclides the data reviewed are consistent with an external stellar origin for most short lived radionuclides 7be 10be and 36cl are important exceptions and a shock wave model for chondrule formation and provide a sound basis for early solar system chronology they are inconsistent with the x wind model for the origin of chondritic components and a local irradiation origin of 26al 41ca and 53mn 10be is heterogeneously distributed among cais indicating its formation by local irradiation and precluding its use for the early solar system chronology 41ca 41k and 60fe 60ni systematics are important for understanding the astrophysical setting of solar system formation and origin of short lived radionuclides but so far have limited implications for the chronology of chondritic components the chronological significance of oxygen isotope compositions of chondritic components is limited the following general picture of formation of chondritic components is inferred cais and aoas were the first solids formed in the solar nebula 4567 4568 myr ago possibly within a period of 10 and have 26al 27al 0 similar to those in chondrules 5 nebular gas the majority of chondrules within a chondrite group may have formed over a much shorter period of time

earthquakes as self organized critical phenomena a cellular automation model with threshold elements previously proposed by bak et al 1988 which generates 1 f noise and self organizes into a critical state is studied as a model for earthquake occurrence the model explains some of fractal features of earthquakes such as the power law distribution of the size of the earthquake the model is modified so that every earthquake may trigger aftershocks the modified trigger model explains other fractal features of earthquakes such as the power law decay of aftershock frequency and the power law decay of aftershock frequency and the power law correlation of the hypocenter distribution

are ureilites residues from partial melting of chondritic material the answer from magpox calculations performed using magpox show that no bulk compositions having chondritic ca al ratio and within the range of chondritic si mg ratios can produce the olivine pigeonite ureilites which constitute 65 of those for which modal abundances are known as residues of single stage equilibrium partial melting calcium aluminum ratios of 2 3 5 ci are required in addition all the ureilites could not have formed from a single composition at various degrees of reduction because they show no correlation between pigeonite olivine ratio and mg ratio materials with various al mg ratios ranging from subchondritic to superchondritic are required if these materials are primitive i e created by nebular processes rather than planetary igneous processes they are unknown in the meteorite record excess accretion relative to chondrites of 5 10 mol of a high temperature condensate component which was itself almost completely depleted in corundum due to early fractionation could create the necessary compositions the plausibility that such processes occurred on a parent body sized scale is difficult to assess in contrast lodranites can be produced as residues of 3 30 equilibrium partial melting of an average ordinary chondritic composition at the appropriate level of reduction although many features of ureilites suggest that they are relatively primitive residues produced by low degrees of melting of chondritic materials and thus resemble lodranites and other groups of primitive achondrites their predominantly pigeonite olivine mineralogy remains difficult to explain within this simple scenario

the marine record of deglaciation of the south shetland islands antarctica since the last glacial maximum abstract the marine geological record of the glacial retreat history of the south shetland islands is derived from the integration of seismic data core lithofacies radiocarbon ages and geomorphological data from two study areas on the northern shelf we present one of the first published multibeam bathymetric images of the seafloor this new image combined with descriptions of new and existing short sediment cores and high resolution seismic data from the continental shelf north of king george island are used to map a grounding zone wedge that marks the minimum seaward extent of the south shetland ice cap during the last glacial maximum seismic data multibeam bathymetry and sediment cores from maxwell bay on the opposite side of king george island are used to provide further spatial constrains on the history of grounding and retreat of the ice cap along the southern margin of the south shetland islands during the last glacial maximum the south shetland ice cap extended onto the outer continental shelf some 50 km north of its present location the ice grounded on the shelf in troughs in present water depths of almost 400 m it had a minimum thickness of 570 m and was also grounded in the deepest part of fjords and straits between the islands to the south the ice cap extended seaward of the mouths of fjords and straits to the steep northern boundary of the bransfield strait sediment eroded from the fjords and straits was deposited in prominent fans that extend into the bransfield strait and show evidence for an ice shelf that covered the bransfield strait during the last glacial maximum a long drill core shaldril in maxwell bay and several jumbo piston cores yielded carbonate material used to constrain the timing and spatial extent of glacial retreat within maxwell bay the oldest glacimarine sediments in the fjord date back to 14 1 to 14 8 ka and suggest an initial deglaciation earlier than most previous studies of the south shetland islands upper maxwell bay was ice free by 9 1 ka and most of maxwell bay proper was ice free by 5 9 ka except for the smaller tributary fjords of maxwell bay these smaller tributary fjords were ice free by 1 7 ka but may have been ice free earlier but reoccupied by a neoglacial advance that ended approximately 1 7 ka

generation and polybaric differentiation of east greenland early tertiary flood basalts major element trace element isotope and petrographic studies of magma diverentiation mantle melting the basal volcanics in the kangerdlugssuaq fjord region of the east greenland margin provide constraints on the generation and subsequent diverentiation and contamination histories of magmas during the early stage of continental rifting creating the north atlantic ocean basin most primitive lavas of the succession are introduction shown to have accumulated olivine corrections for crystal ac the distinctive geochemical features of continental flood cumulation yield estimates for erupted primitive liquids with mgo basalts cfbs are strongly controlled by the composition contents between 9 and 13 wt the occurrence of suspended and structure of the continental lithosphere and underfo88 olivine phenocrysts further requires the existence of parental lying mantle significant controversy remains concerning magmas with mgo contents up to 17 wt and feo contents up the balance of contributions from the lithosphere and to 14 wt quantitative modeling of fractionation indicates the mantle and the mechanisms by which the various that kangerdlugssuaq magmas primarily diverentiated at moderate source components contribute to basalt petrogenesis pressures 8 kbar to form dunitic and wehrlitic cumulates at how are basalt compositions influenced by generation depths of 25 km evolved east greenland flood basalts from the in anomalous regions in the deep mantle plumes by scoresby sund region record a more complex fractionation history interaction between rising magmas and the continental involving olivine clinopyroxene fractionation in the lower crust lithospheric mantle and by contamination with conas found for the lower basalts followed by olivine plagioclase tinental crust how are the diverentiation con clinopyroxene fractionation at shallow crustal levels cor tamination magma mixing and storage histories of cfbs relations between sio2 incompatible elements and sr nd isotopic controlled by the structure of the continental lithosphere ratios for the lower basalts are consistent with bulk assimilation and how do the thermal and chemical features of the of up to 15 20 archean leucogneiss with unradiogenic sr and mantle and the extensional history of the continental nd isotopic ratios characteristic of lewisian type lower crust lithosphere avect mantle melting and compositions of comparisons between inferred magma types for lower basalts and primary liquids estimated primary liquids from elsewhere in the north atlantic these questions are best addressed in the context of show complex relationships among feo mgo tio2 contents a geologically and geochemically well constrained cfb and cao al2o3 ratios that relate to regional and temporal changes province such as the north atlantic tertiary province in mantle temperatures lithospheric thickness and involvement of separation of east greenland from northern europe in at least two end member mantle sources we postulate that the the early tertiary at 60 myr ago was accompanied by lower basalts of east greenland were derived from iron poor voluminous volcanic activity the blosseville coast of mantle depleted by prior melt extraction and distinct from morb east greenland extending from kangerdlugssuaq fjord source mantle that was enriched in tio2 and lrees by a to scoresby sund fig 1 contains spectacularly exposed metasomatic event shortly before early tertiary magmatism we sections of lavas these sections begin at the basal contact associate this depleted mantle source with the ancestral iceland of the lavas with underlying cretaceous tertiary sediments and archean basement and continue to the plume anomaly

a new bathymetric compilation highlighting extensive paleo ice sheet drainage on the continental shelf south georgia sub antarctica a grid derived from a new compilation of marine echo sounding data sets has allowed us to visualize and map the geomorphology of the entire continental shelf around south georgia at an unprecedented level of detail the grid is the first continuous bathymetric data set covering south georgia to include multibeam swath bathymetry and represent them at a subkilometer resolution large and previously undescribed glacially eroded troughs linked to south georgia s modern day fjords radiate from the island marking the former pathways of large outlet glaciers and ice streams a tectonic or geological influence is apparent for the major troughs where glaciers have exploited structural weaknesses on the continental block bed forms lining the troughs give some first insights into glacial dynamics within the troughs suggesting arteries of fast flowing ice occupied these topographic depressions in the past and operated over both bedrock and sedimentary substrates on the outer shelf and within the troughs large ridges and banks are also common interpreted as terminal lateral and recessional moraines marking former positions of ice sheets on the shelf and their subsequent reorganization during deglaciation a small trough mouth fan has developed at the mouth of at least one of the cross shelf troughs demonstrating a focused sediment delivery to the margin slides and slide scars are also present on parts of the margin showing that margin stability perhaps also related to glaciation has been an important factor in depositional processes on the continental slope implications of the new observations are that ice sheets have been more extensive on south georgia than any previous studies have reported their age may date back to late miocene times and evolution of the shelf system has probably involved numerous late cenozoic glacial episodes however relatively fresh seafloor geomorphology coupled with evidence from other maritime antarctic islands heard island and kerguelen island indicating extensive glaciation at the last glacial maximum raises the possibility that the extent of sub antarctic glaciation for the last glacial period has until now been underestimated

the last glacial holocene transition in southern chile warming at the last glacial termination in the north atlantic region was interrupted by a period of renewed glacial activity during the younger dryas chronozone ydc the underlying mechanism of this cooling remains elusive but hypotheses turn on whether it was a global or a north atlantic phenomenon chronological sedimentological and palaeoecological records from sediments of small lakes in oceanic southern chile demonstrate that there was no ydc cooling in southern chile it is therefore likely that there was little or no cooling in southern pacific surface waters and hence that ydc cooling in the north atlantic was a regional rather than global phenomenon

earthquake prediction a critical review summary earthquake prediction research has been conducted for over 100 years with no obvious successes claims of breakthroughs have failed to withstand scrutiny extensive searches have failed to find reliable precursors theoretical work suggests that faulting is a non linear process which is highly sensitive to unmeasurably fine details of the state of the earth in a large volume not just in the immediate vicinity of the hypocentre any small earthquake thus has some probability of cascading into a large event reliable issuing of alarms of imminent large earthquakes appears to be effectively impossible key word earthquake prediction

paleocean circulation during the last deglaciation a bipolar seesaw hughen et al 1998 have documented that during the first 200 years of younger dryas time the 14c content of atmospheric co2 increased by 50 and that during the remainder of this 1200 year duration cold event it steadily declined the initial increase in 14c c was likely the result of a reduction in the atlantic s conveyor circulation however were the subsequent radiocarbon decline due to the rejuvenation of this potent heat pump then it is difficult to understand why the climate conditions in the northern atlantic basin remained cold throughout the younger dryas modeling exercises by stocker and wright 1996 mikolajewicz 1998 and schiller et al 1998 show that if the conveyor is terminated the transfer of radiocarbon into the deep sea shifts to the southern ocean thereby stabilizing the atmospheric 14c c ratio paleoclimatic evidence from the antarctic continent suggests that this model based scenario might have been played out in the real world while the younger dryas cooling has been documented in many places around the world including new zealand denton and hendy 1994 sowers and bender 1995 using their 18o in o2 based correlation between the ice core 18o in ice records for antarctica and greenland have demonstrated that in antarctica the younger dryas was a time of maximum warming the point of this paper is that the steep rise in 18o rise in antarctic ice which commenced close to the onset of the younger dryas might have been caused by heat released to the atmosphere in response to an increase in deep sea ventilation in the southern ocean

terrestrial and submarine evidence for the extent and timing of the last glacial maximum and the onset of deglaciation on the maritime antarctic and sub antarctic islands this paper is the maritime and sub antarctic contribution to the scientific committee for antarctic research scar past antarctic ice sheet dynamics pais community antarctic ice sheet reconstruction the overarching aim for all sectors of antarctica was to reconstruct the last glacial maximum lgm ice sheet extent and thickness and map the subsequent deglaciation in a series of 5000 year time slices however our review of the literature found surprisingly few high quality chronological constraints on changing glacier extents on these timescales in the maritime and sub antarctic sector therefore in this paper we focus on an assessment of the terrestrial and offshore evidence for the lgm ice extent establishing minimum ages for the onset of deglaciation and separating evidence of deglaciation from lgm limits from those associated with later holocene glacier fluctuations evidence included geomorphological descriptions of glacial landscapes radiocarbon dated basal peat and lake sediment deposits cosmogenic isotope ages of glacial features and molecular biological data we propose a classification of the glacial history of the maritime and sub antarctic islands based on this assembled evidence these include type i islands which accumulated little or no lgm ice type ii islands with a limited lgm ice extent but evidence of extensive earlier continental shelf glaciations type iii seamounts and volcanoes unlikely to have accumulated significant lgm ice cover type iv islands on shallow shelves with both terrestrial and submarine evidence of lgm and or earlier ice expansion type v islands north of the antarctic polar front with terrestrial evidence of lgm ice expansion and type vi islands with no data finally we review the climatological and geomorphological settings that separate the glaciological history of the islands within this classification scheme

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

temperature change is the major driver of late glacial and holocene glacier fluctuations in new zealand advance and retreat of temperate glaciers is largely controlled by changes in temperature and precipitation but the relative importance of these drivers is debated numerical modeling of a new zealand glacier reveals that temperature is the dominant control on glacier length we find that a glacial advance dated to ca 13 000 yr b p requires a cooling event of 3 4 c this mid latitude southern hemisphere cooling is similar in magnitude to the antarctic cold reversal in the vostok ice core record and likely to be a response to the same climate signal

palaeolimnological evidence for marked holocene environmental changes on signy island antarctica lake sediment cores from heywood and sombre lakes on signy island south orkney islands antarctica have yielded a conformable radiocarbon chronology for the holocene and a high resolution record of environmental change the lakes share a common climate and geology but have distinct catchments this provides an opportunity for using lake sediments to differentiate between local within lake catchment events and those at a regional scale analyses of various biological and physical remains from the lakes suggest that both catchments have undergone considerable changes during the last 5700 years macrofossils moss and crustacean remains are more abundant in the late holocene being associated with a period of high sediment accumulation which is related to diatom evidence for more nutrient rich conditions at the sites this is inter preted as a response to a holocene climate optimum at c 3800 1300 14 c yr bp the record is consistent with other lake ice and ocean core studies although the climate optimum appears to have persisted for a longer period at signy island

petrology of the yamato nakhlites the yamato nakhlites y 000593 y 000749 and y 000802 were recovered in 2000 from the bare icefield around the yamato mountains in antarctica consisting of three independent specimens with black fusion crusts they are paired cumulate clinopyroxenites we obtained the intercumulus melt composition of the yamato nakhlites and here call it the yamato intercumulus melt yim the yim crystallized to form the augite rims the olivine rims and the mesostasis phases in the cumulates the augite rims consist of two layers inner and outer the crystallization of the inner rim drove the interstitial melt into the plagioclase liquidus field subsequently the residual melt crystallized pigeonites and plagioclase to form the outer rims and the mesostasis three types of inclusions were identified in olivine phenocrysts rounded vitrophyric angular vitrophyric and monomineralic augite inclusions the monomineralic augite inclusions are common and may have been captured by growing olivine phenocrysts the rounded vitrophyric inclusions are rare and may represent the composition of middle stage melts whereas the angular vitrophyric inclusions seem to have been derived from fractionated late stage melts glass inclusions occur in close association with titanomagnetite and ferroan augite halo in phenocryst core augites and the assemblages may be magmatic inclusions in augites we compared the yim with compositions of magmatic inclusions in olivine and augite the composition of magmatic inclusions in augite is similar to the yim phenocrystic olivines contain exsolution lamellae augite magnetite aggregates and symplectites in the cores the symplectites often occur at the boundaries between olivine and augite grains the aggregates symplectite and lamellae formed by exsolution from the host olivine at magmatic temperatures we present a formational scenario for nakhlites as follows 1 accumulation of augite olivine and titanomagnetite phenocrysts took place on the floor of a magma chamber 2 olivine exsolved augite and magnetite as augite magnetite aggregates symplectites and lamellae 3 the overgrowth on olivine phenocrysts formed their rims and the inner rims crystallized on augite phenocryst cores and finally 4 the outer rim formed surrounding the inner rims of augite phenocrysts and plagioclase and minor minerals crystallized to form mesostasis under a rapid cooling condition probably in a lava flow or a sill

iceberg scours pits and pockmarks in the north falkland basin abstract glaciation in the southern hemisphere is limited by the availability of land from which to seed ice sheets the extents of the antarctic patagonian and new zealand ice sheets at the last glacial maximum lgm are relatively well known although the rates and styles of their retreat after the lgm are poorly constrained particularly in antarctica offshore records of glaciation are relatively sparse in the southern hemisphere despite the potential ocean climate insights that can be gained from records of glaciation that are preserved offshore in this study we document the occurrence of iceberg scours and accompanying pits within the north falkland basin c 50 s and discuss their origin the cross sectional shapes of scours are u to v shaped and occur in present day water depths of 280 to 460 m individual scours are up to 38 km long 1 km wide and up to 10 m deep the scours are observed as erosional linear to curvilinear depressions showing only one point of contact between the iceberg and seafloor often with raised berms composed of excavated material identified either side of the main depression undulating width of scours is interpreted as an effect of rotation of the iceberg keel during scour excavation the elongate morphology of the scours differentiates them from asymmetrical pits interpreted to represent iceberg impact pits and symmetrical pockmarks interpreted to form due to fluid expulsion in cross section the differentiation is highly interpretative but the 3d bathymetric expression is unequivocal the sinusoidal character of the scours suggests the interaction between local tidal currents and the east falkland malvinas currents in the north falkland basin at the time of formation offshore and onshore landscape analysis is used to determine potential sources of icebergs and suggests that they were most likely sourced from the antarctic peninsula these results inform our understanding of southern hemisphere ocean climate interactions during the last glacial cycle and suggest that the east falklands malvinas current a key current in the southern hemisphere bringing cold low salinity antarctic derived waters into the south atlantic was in operation during the last glacial cycle the accumulation of icebergs west of the falkland islands would also result in further cooling from fresh meltwater perturbations enhancing the development of a potential ice bridge along the argentinian coast

retrospective investigation of geomagnetic field time series during the 2009 l aquila seismic sequence abstract this paper reports the analyses of ulf ultra low frequency geomagnetic field observations coming from the geomagnetic observatory of l aquila during the period 2008 2009 this period includes the l aquila 2009 seismic sequence where the main shock of 6 april heavily damaged the medieval centre of the town and its surrounding area causing 308 deaths more than 1000 injuries and about 60 000 displaced people recently several publications have documented the observation of precursory signals which occurred before the 6 april earthquake e g eftaxias et al 2009 2010 while others do not find any pre earthquake anomaly e g villante et al 2010 di lorenzo et al 2011 in light of this the goal of this study is to carry out further retrospective investigations ulf magnetic field data are investigated by means of conventional analyses of magnetic polarization ratio improved magnetic polarization ratio and fractal analysis in addition total geomagnetic field data coming from the ingv central italy tectonomagnetic network have also been investigated using the simple inter station differentiation method within the limits of these methods no magnetic anomalous signal which may be reasonably characterized as a precursor of the l aquila earthquakes has been found

late glacial and holocene glacier fluctuations and environmental change on south georgia southern ocean south georgia provides a terrestrial record of postglacial environmental change from a largely oceanic zone of the earth the record is representative of the southern westerlies and provides a link between antarctica and the temperate zones of southern south america evidence from glacial geomorphology slope stratigraphy and analyses of environmental indicators in peat and lake cores is used to interpret this record wastage of the full glacial ice cap was interrupted by a late glacial stade of the outlet and valley glaciers before ca 10 000 yr b p plant growth had begun at low altitude 50 m on the sheltered lee side northeast coast within the late glacial moraine limits by 9700 yr b p environmental conditions on slopes above 80 m probably were too rigorous for a stable vegetation cover until ca 6400 yr b p this was followed by a period from 5600 to 4800 yr b p when conditions were warmer than at present by up to 0 6 c periods of climatic cooling occurred at ca 4800 3800 yr b p ca 3400 1800 yr b p and within the last 1400 yr the most extensive holocene advance of south georgia glaciers culminated just before 2200 yr b p these holocene temperature changes of between 0 5 and 1 0 c are comparable in scale and timing to those identified from recent analyses of vostok ice cores from the antarctic ice sheet

antarctic timing of surface water changes off chile and patagonian ice sheet response marine sediments from the chilean continental margin are used to infer millennial scale changes in southeast pacific surface ocean water properties and patagonian ice sheet extent since the last glacial period our data show a clear antarctic timing of sea surface temperature changes which appear systematically linked to meridional displacements in sea ice westerly winds and the circumpolar current system proxy data for ice sheet changes show a similar pattern as oceanographic variations offshore but reveal a variable glacier response time of up to 1000 years which may explain some of the current discrepancies among terrestrial records in southern south america

glacial geomorphology and chronology in the selamiut range nachvak fiord area torngat mountains labrador the summits of the selamiut range are the highest in the torngat mountains of northern labrador and contain some of the only permanent ice bodies of the eastern canadian mainland as they may have constituted a physical barrier to ice moving eastward from the ungava ice dispersal centre their glacial history is elaborate in a regional context consequently a complex interaction of local and regional ice masses is manifest in the morphochronological record dating from the late quaternary through the holocene physiographically the selamiut range is a plateau dominated by deep cirques and cirque outlet valleys with precipitous bounding rock walls colluvial processes are extremely active and consequently many surficial units have been extensively remodelled in dynamic landscape systems the northern half of the field area contains a wealth of glacial and periglacial landform assemblages and former local and regional ice activity has been determined from the cross cutting relationships of certain morainic features within the mccornick river valley a sequence of shorelines documents the depths and extent of ice dammed lakes during glaciation a further 33 metre marine limit demarcates former sea level during the final glaciation of the area three glaciations or stillstands are suggested for the field area after consideration of the landform evidence and are named the ivitak nachvak and superguksoak glaciations the adoption of a 1 5 cm ka soil development rate dates the three glaciations or stillstands for the selamiut nachvak area the ivitak glaciation at 40 ka the nachvak glaciation at c 23 ka and the superguksoak i glaciation at 10 12 ka b p two further neoglacial events were restricted to the cirque basins and are correlated locally by a combination of pedology lichenometry and morphologic superimposition a number of chronocorrelative inferences are made for northern labrador based upon the existing empirical data glacial styles appear to differ quite considerably from fiord to fiord along the coastal section of the torngat mountains the solution of discrepancies within the general northern labrador chronology resides in the successful construction of an absolute dating framework for the marine limits of the region relative chronologies may then attain a significant applicability

on the reported magnetic precursor of the 1989 loma prieta earthquake among the most frequently cited reports in the science of earthquake prediction is that by fraser smith et al 1990 and bernardi et al 1991 they found anomalous enhancement of magnetic field noise levels prior to the 18 october 1989 loma prieta earthquake in the ultra low frequency range 0 0110 10 001 hz from a ground based sensor at corralitos ca just 7 km from the earthquake epicenter in this analysis we re examine all of the available corralitos data 21 months from january 1989 to october 1990 and the logbook kept during this extended operational period we also examine 1 0 hz 1 s data collected from japan 0 0167 hz 1 min data collected from the fresno ca magnetic observatory and the global kp magnetic activity index the japanese data are of particular importance since their acquisition rate is sufficient to allow direct comparison with the lower frequency bands of the corralitos data we identify numerous problems in the corralitos data evident from both straightforward examination of the corralitos data on their own and by comparison with the japanese and fresno data sets the most notable problems are changes in the baseline noise levels occurring during both the reported precursory period and at other times long before and after the earthquake we conclude that the reported anomalous magnetic noise identified by fraser smith et al and bernardi et al is not related to the loma prieta earthquake but is an artifact of sensor system malfunction 2008 elsevier b v all rights reserved

scaling factors for the rates of production of cosmogenic nuclides for geometric shielding and attenuation at depth on sloped surfaces abstract the decrease in rates of production of cosmogenic nuclides occurs because of shielding of cosmic rays by mountains sloped surfaces and local rock formations that block them when a large part of the sky is blocked this correction is large and requires detailed model calculations this paper considers three geometries a rectangular obstruction a triangular obstruction and a sloped surface other geometries can be considered as a combination of these the results are presented in terms of formulas and graphs so that the reader can easily apply them to common field situations any use of cosmogenic nuclides in the study of geomorphic processes or forms must consider factors that introduce variations in the production of nuclides

testing models of ice cap extent south georgia sub antarctic the extent of last glacial maximum ice in south georgia is contested with two alternative hypotheses an extensive maximum model of ice reaching the edge of the continental shelf or a restricted minimum model with ice constrained within the inner fjords we present a new relative sea level dataset for south georgia summarising published and new geomorphological evidence for the marine limit and elevations of former sea levels on the island using a glacial isostatic adjustment model alma specifically suited to regional modelling and working at high spatial resolutions combined with a series of simulated ice load histories we use the relative sea level data to test between the restricted and extensive ice extent scenarios the model results suggest that there was most likely an extensive last glacial maximum glaciation of south georgia implying that the island was covered by thick 1000 m ice probably to the edge of the continental shelf with deglaciation occurring relatively early ca 15 ka bp though independent data suggest this may have been as early as 18 ka the presence of an extensive ice cap extending to the shelf edge would imply that if there were any biological refugia around south georgia they must have been relatively localised and restricted to the outermost shelf

a 25 000 year tropical climate history from bolivian ice cores ice cores that were recovered from the summit of sajama mountain in bolivia provide carbon 14 dated tropical records and extend to the late glacial stage lgs oxygen isotopic ratios of the ice decreased 5 4 per mil between the early holocene and the last glacial maximum which is consistent with values from other ice cores the abrupt onset and termination of a younger dryas type event suggest atmospheric processes as the probable drivers regional accumulation increased during the lgs during deglaciation and over the past 3000 years which is concurrent with higher water levels in regional paleolakes unlike polar cores sajama glacial ice contains eight times less dust than the holocene ice which reflects wetter conditions and extensive snow cover

results of ultra low frequency magnetic field measurements during the guam earthquake of 8 august 1993 we report the results of measurements of ultra low frequency magnetic noise during a large earthquake ms 7 1 at guam of 8 august 1993 depth 60 km the ulf observing system is located in the guam island about 65 km from the epicenter several distinct features of this analysis are summarized 1 we have proposed rather sophisticated statistical analyses monthly mean standard deviation in order to estimate the wave intensity and polarization i e ratio z h 2 a comparison between the ulf wave activity and kp is useful in distinguishing between the space geomagnetic pulsations and non space emissions 3 then the use of the ratio z h is found to be of essential importance in discrimating the emissions presumably of seismic origin from space plasma waves 4 the statistical analysis of the temporal evolution of this ratio has yielded that it shows a broad maximum only about one month before the earthquake and this suggests that the emissions during this period are very likely to be magnetic precursors 5 the temporal variation of z component is similar to that for the loma prieta earthquake such that it shows a broad maximum ten days two weeks before the earthquake and another increase a few days before the earthquake 6 the emissions presumably associated with the earthquake are of noise like nature and their main frequency is 0 02 0 05 hz with maximum intensity 0 1 nt

climatic interpretation of the recently extended vostok ice records a new ice core drilled at the russian station of vostok in antarctica reached 2755 m depth in september 1993 at this depth the glaciological time scale provides an age of 260 ky bp 25 we refine this estimate using records of dust and deuterium in the ice and of 18o of o2 in the entrapped air 18o of o2 is highly correlated with insolation over the last two climatic cycles if one assumes that the egt chronology overestimates the increase of age with depth by 12 for ages older than 112 ky bp this modified age depth scale gives an age of 244 ky bp at 2755 m depth and agrees well with the age depth scale of walbroeck et al in press derived by orbital tuning of the vostok d record we discuss the temperature interpretation of this latter record accounting for the influence of the origin of the ice and using information derived from deuterium excess data we conclude that the warmest period of stage 7 was likely as warm as today in antarctica a remarkable feature of the vostok record is the high level of similarity of proxy temperature records for the last two climatic cycles stages 6 and 7 versus stages 1 5 this similarity has no equivalent in other paleorecords

results of ulf magnetic field measurements near the epicenters of the spitak ms 6 9 and loma prieta ms 7 1 earthquakes comparative analysis the characteristics of the ulf magnetic field emissions measured at two magnetic observatories in the republic of georgia prior to and after the ms 6 9 earthquake that occurred near spitak armenia on december 7 1988 are compared with the apparently similar emissions associated with the ms 7 1 earthquake that occurred near loma prieta california on october 17 1989 the main features of the spitak measurements according to observations made at the dusheti station 128 km to the spitak epicenter as compared with the loma prieta measurements which were made at corralitos california 7 km to the loma prieta epicenter are the following 1 the intensity of ulf background activity started growing 3 to 5 days before the spitak earthquake whereas the corresponding increase in activity began 12 days before the loma prieta earthquake 2 a substantial ulf emission burst was recorded at dusheti starting 4 hours prior to the main shock a similar large burst of ulf activity commenced 3 hours before the loma prieta event and continued until the occurrence of the main shock 3 ulf activity remained high for about two weeks after the spitak earthquake and for several months after the loma prieta earthquake 4 ulf noise bursts were observed 1 to 6 hours before powerful aftershocks at spitak during the period of enhanced activity but there was no conclusive link between the ulf noise at corralitos and the after shocks a major difference in the ulf activity preceding the two earthquakes is a difference in amplitude 0 2 nt at spitak and 5 nt at loma prieta but this is easily explained as being caused by the different distances of the observation stations from the epicenters

signature of pending earthquake from electromagnetic anomalies two electromagnetic em anomalies have been detected in the vlf frequency band before the athens earthquake eq mw 5 9 sept 7 1999 with the following characteristics i the first and second anomaly lasted for 12 and 17 hours respectively with a cessation of 12 hours ii the second anomaly ceased at about 9 hours before the eq iii the larger anomaly the second one contains approximately 80 of the total em energy received iv no em disturbance has been recorded in the vhf frequency band unlike with other cases e g the kozani grevena and egion eratini earthquakes the fault modeling of the athens eq based on information obtained by radar interferometry predicts two faults the main fault segment is responsible for 80 of the total energy released while the secondary fault segment for the remaining 20 moreover a recent seismic data analysis supports the hypothesis that a two event solution for the athens eq is more likely than a single event solution in addition the absence of surface rupture explains the absence of em detection in the vhf frequency band the present analysis reveals that the properties of the preseismic electromagnetic anomalies might be considered as signatures of a pending earthquake

anhydrous liquid line of descent of yamato 980459 and evolution of martian parental magmas we report the results of nominally anhydrous equilibrium and fractional crystallization experiments on a synthetic yamato 980459 y98 bulk composition at 0 5 gpa these experiments allow us to test a suggested fractional crystallization model calculated using melts by symes et al 2008 in which a y98 like initial liquid yielded a magma closely resembling the bulk composition of que 94201 although the two meteorites cannot be cogenetic owing to their age difference they are thought to represent bona fide magmatic liquids rather than products of crystal accumulation as are most martian basaltic meteorites hence understanding possible petrogenetic links between these types of liquids could be revealing about processes of melting and crystallization that formed the range of martian basalts we find that y98 can in fact generate a residual liquid closely resembling que but only after a very different crystallization process and different degree of crystallization than that modeled using melts in addition both the identity and sequence of crystallizing phases are very different between model and experiments our fractional crystallization experiments do not produce a que like liquid and the crystallizing phases are an even poorer match to the melts calculated compositions than in the equilibrium runs however residual liquids from our experiments define a liquid line of descent that encompasses bulk compositions of parental melts calculated for several martian basaltic meteorites suggesting that the known martian basaltic meteorites had their ultimate origin from the same or very similar source lithologies these are in turn similar to source rocks modeled by previous studies as products of extensive crystallization of an initial martian magma ocean

tectonomagnetic field observations in central italy 1989 1995 abstract it has been reported that earthquakes and volcanic eruptions produce significant variations in the geomagnetic field to investigate possible tectonomagnetic effects related to seismic activity the istituto nazionale di geofisica installed a seismomagnetic network in central italy the area was selected after a magnetic noise survey geomagnetic field intensity data are simultaneously recorded at four magnetometer stations and at l aquila geomagnetic observatory which is located in the same area the data are differentiated in order to detect local magnetic field anomalies the present study reports geomagnetic field observations in central italy from july 1989 to march 1995 and also discusses the detectability of a tectonomagnetic effect in this area a variation of about 5 nt over a two month period january february 1990 has been observed in the geomagnetic field no other anomaly has been observed although moderate seismicity occurred in central italy during the study period

late glacial to middle holocene climatic record of lacustrine biogenic silica oxygen isotopes from a southern ocean island late glacial to middle holocene climatic record of lacustrine biogenic silica oxygen isotopes from a southern ocean island

sub antartic glacier extensions in the kerguelen region 49 s indian ocean over the past 24 000 years constrained by 36cl moraine dating similar to many other regions in the world glaciers in the southern sub polar regions are currently retreating in the kerguelen islands 49 s 69 e the mass balance of the cook ice cap cic the largest ice cap in this region experienced dramatic shrinking between 1960 and 2013 with retreat rates among the highest in the world this observation needs to be evaluated in a long term context however data on the past glacier extents are sparse in the sub antartic regions to investigate the deglaciation pattern since the last glacial maximum lgm period we present the first 13 cosmogenic 36cl surface exposure ages from four sites in the kerguelen islands the 36cl ages from erratic and moraine boulders span form 24 4 2 7 ka to 0 3 0 1 ka we combined these ages with existing glacio marine radiocarbon ages and bathymetric data to document the temporal and spatial changes of the island s glacial history ice began to retreat on the main island before 24 4 2 7 ka until around the time of the antartic cold reversal acr period 14 5 12 9ka during which the bontemps moraine was formed by the advance of a cic outlet glacier deglaciation continued during the holocene probably until 3ka with evidence of minor advances during the last millennium the chronology is in pace with major changes in 18o in a recent west antarctica ice core record showing thet kerguelen islands glciers are particularly sensitive and relevant to document climate change in the southern polar regions

a new estimate of the holocene lowstand level of lake titicaca central andes and implications for tropical palaeohydrology new evidence from piston cores and high resolution seismic reflection data shows that water levels in lake titicaca were as much as 100 m below the present level during the early to mid holocene between 6 and 3 8 14c kyr bp climatological and modelling studies indicate that lake titicaca rainfall depends on convective activity in upwind amazonia the lake level data therefore suggest a drier amazon basin during this time this view is bolstered by an excellent match between the titicaca lake level curve and decreased methane concentrations in greenland ice previously ascribed to drying of low latitude wetlands blunier et al 1995 the postglacial history of lake titicaca fits a global pattern of lake level change in the tropics characterized by opposite phasing between the southern and northern hemispheres this pattern is most likely the result of orbital controls over the intensity of summer insolation

changes in holocene climate and the intensity of southern hemisphere westerly winds based on a high resolution palynological record from sub antarctic south georgia sub antarctic south georgia is a key region for studying climate variability in the southern hemisphere because of its position at the core of the southern hemisphere westerly wind belt and between the antarctic circumpolar current and the polar frontal zone here we present a 5 8 m long high resolution pollen record from fan lake on annenkov island dominated by local sub polar vegetation with acaena and poaceae being present throughout the last 7000 years palynological and sedimentological analyses revealed a warm late holocene climate optimum between 3790 and 2750 cal yr bp which was followed by a gradual transition to cool and wet conditions this cooling was interrupted by slightly warmer environmental conditions between 1670 and 710 cal yr bp that partly overlap with the northern hemisphere medieval climate anomaly increases in non native and long distance pollen grains transported from south america e g nothofagus podocarpus indicate that stronger southern hemisphere westerly winds over south georgia possibly occurred during some colder phases of the late holocene most notably between c 2210 and 1670 cal yr bp and after 710 cal yr bp

sedimentology and chronology of the advance and retreat of the last british irish ice sheet on the continental shelf west of ireland the last british irish ice sheet biis had extensive marine terminating margins and was drained by multiple large ice streams and is thus a useful analogue for marine based areas of modern ice sheets however despite recent advances from investigating the offshore record of the biis the dynamic history of its marine margins which would have been sensitive to external forcing s remain inadequately understood this study is the first reconstruction of the retreat dynamics and chronology of the western marine terminating margin of the last late midlandian biis analyses of shelf geomorphology and core sedimentology and chronology enable a reconstruction of the late midlandian history of the biis west of ireland from initial advance to final retreat onshore five ams radiocarbon dates from marine cores constrain the timing of retreat and associated readvances during deglaciation the biis advanced without streaming or surging depositing a bed of highly consolidated subglacial traction till and reached to within 20 km of the shelf break by 24 000 cal bp ice margin retreat was likely preceded by thinning grounding zone retreat and ice shelf formation on the outer shelf by 22 000 cal bp this ice shelf persisted for 2500 years while retreating at a minimum rate of 24 m yr and buttressing a 150 km long 20 km wide bathymetrically controlled grounding zone a large 150 km long arcuate flat topped grounding zone wedge termed here the galway lobe grounding zone wedge glgzw was deposited below this ice shelf and records a significant stillstand in biis retreat geomorphic relationships indicate that the biis experienced continued thinning during its retreat across the shelf which led to increased topographic influence on its flow dynamics following ice shelf break up and grounding zone retreat past the glgzw at this stage of retreat the western biis was comprised of several discrete asynchronous lobes that underwent several readvances sedimentary evidence of dilatant till deposition suggests that the readvances may have been rapid and possibly associated with ice streaming or surging the largest lobe extended offshore from galway bay and deposited the galway lobe readvance moraine by 18 500 cal bp further to the north an ice lobe readvanced at least 50 km offshore from killary harbour possibly by 15 100 cal bp the existing chronology currently does not allow us to determine conclusively whether these readvances were a glaciodynamic internally driven response of the ice sheet during deglaciation or were climatically driven following the 18 500 cal bp readvance the galway lobe experienced accelerated eastward retreat at an estimated rate of 113 m yr

cosmic ray production rates of 10be and 26al in quartz from glacially polished rocks we have studied the concentrations of 10be and 26al in quartz crystals extracted from glacially polished granitic surfaces from the sierra nevada range these surfaces were identified with the glacial advance during the tioga period 11 000 years ago our measurements yield the most accurate estimates to date for the absolute production rates of these nuclides in sio2 due to cosmic ray nucleons and muons for geomagnetic latitudes 43 8 44 6 n and altitudes 2 1 3 6 km the estimates are relatively free from uncertainties in snow cover since we studied a suite of rock surfaces inclined 0 75 with respect to the horizontal the principal uncertainty arises due to the lack of a precise date for the glacial retreat event about 10 the 26al 10be ratio at production 6 0 is determined more accurately since the exposure age of the samples is 2 orders of magnitude smaller than the mean lives of the two nuclides production rates of 10be and 26al in quartz at other latitudes and altitudes in the troposphere can be determined from the present measurements by scaling using the known altitude and latitude dependence of cosmic ray fluxes of nucleons and negative muons knowledge of the production rates of these nuclides is a prerequisite for their application in erosion and geomorphological studies

late holocene glacier reconstruction reveals retreat behind present limits and two stage little ice age on subantarctic south georgia observational data show that climate in the southern ocean region is rapidly changing however past the instrumental period our understanding of climate variability in the region is limited by a scarcity of highresolution palaeoclimate records alpine glaciers present on many southern ocean islands may provide such data because changes in their mass balance extent and erosion rates often mark a response to climate shifts rock flour the fine grained fraction of the glacial erosion process is suspended in meltwater streams and transferred into the sediments of downstream lakes continuously recording glacier variations here we utilize this relationship to present a reconstruction of the late holocene glacier history of subantarctic south georgia using sediments from the glacier fed middle hamberg lake to fingerprint a glacial erosion size signal we used titanium counts validated against changes in sediment density and grain size allowing a continuous reconstruction of glacier variations over the past similar to 1250 years together with local moraine evidence and supporting evidence from other southern hemisphere glaciers on new zealand and in patagonia our findings reveal a series of consecutively diminishing late holocene advances in addition to a glacier maximum before 1250 cal a bp these include a twostage litle ice age with advances around 300 and 120 cal a bp in line with evidence from southern patagonia in addition we present evidence for an unreported retreat behind present limits around 500 cal bp

seismomagnetic effects from the long awaited 28 september 2004 m 6 0 parkfield earthquake precise measurements of local magnetic fields have been obtained with a differentially connected array of seven synchronized proton magnetometers located along 60 km of the locked to creeping transition region of the san andreas fault at parkfield california since 1976 the m 6 0 parkfield earthquake on 28 september 2004 occurred within this array and generated coseismic magnetic field changes of between 0 2 and 0 5 nt at five sites in the network no preseismic magnetic field changes exceeding background noise levels are apparent in the magnetic data during the month week and days before the earthquake or expected in light of the absence of measurable precursive deformation seismicity or pore pressure changes obser vations of electric and magnetic fields from 0 01 to 20 hz are also made at one site near the end of the earthquake rupture and corrected for common mode signals from the ionosphere magnetosphere using a second site some 115 km to the northwest along the fault these magnetic data show no indications of unusual noise before the earthquake in the ulf band 0 01 20 hz as suggested may have preceded the 1989 ml 7 1 loma prieta earthquake nor do we see electric field changes similar to those suggested to occur before earthquakes of this magnitude from data in greece uni form and variable slip piezomagnetic models of the earthquake derived from strain displacement and seismic data generate magnetic field perturbations that are con sistent with those observed by the magnetometer array a higher rate of longer term magnetic field change consistent with increased loading in the region is apparent since 1993 this accompanied an increased rate of secular shear strain observed on a two color edm network and a small network of borehole tensor strainmeters and increased seismicity dominated by three m 4 5 5 earthquakes roughly a year apart in 1992 1993 and 1994 models incorporating all of these data indicate increased slip at depth in the region and this may have played a role in the final occurrence of the 28 september 2004 m 6 0 parkfield earthquake the absence of electric and magnetic field precursors for this and other earthquakes with m 5 7 3 elsewhere in the san andreas fault system indicates useful prediction of damaging earthquakes seems unlikely using these electromagnetic data

timing of millennial scale climate change in antarctica and greenland during the last glacial period a precise relative chronology for greenland and west antarctic paleotemperature is extended to 90 000 years ago based on correlation of atmospheric methane records from the greenland ice sheet project 2 and byrd ice cores over this period the onset of seven major millennial scale warmings in antarctica preceded the onset of greenland warmings by 1500 to 3000 years in general antarctic temperatures increased gradually while greenland temperatures were decreasing or constant and the termination of antarctic warming was apparently coincident with the onset of rapid warming in greenland this pattern provides further evidence for the operation of a bipolar see saw in air temperatures and an oceanic teleconnection between the hemispheres on millennial time scales

crystallization experiments of intercumulus melts for nakhlites under qfm 2 at 1 bar crystallization of parent melts for nakhlites was experimentally studied under qfm 2 at one bar isothermal experiments suggest that melts having parent magma composition for nakhlites crystallize both augites and titanomagnetites at liquidus temperatures of 11441154 c compositions of the augites are identical to those of phenocrystic core augites en36 38fs22 25wo39 40 in nakhlites no olivines crystallize from the isothermal runs and solidus temperature is about 1000 c linear cooling experiments were carried out at various cooling rates 117 c h ranging from liquidus to solidus temperatures under similar pressure conditions to the isothermal runs augites titanomagnetites and fayalites crystallized in the cooling runs but magnesian olivines never crystallized there magnesian core augite in the cooling runs has the same composition as those of nakhlites rims of augite crystals from the cooling runs of 1 4 c h consist of two layers ferroan augite inner rim and hedenbergite outer rim which are very similar to those in the miller range mil 03346 nakhlite small amounts of pyroxferroite crystallized in mesostasis and augite rims from two cooling runs titanomagnetites from cooling runs never accompany ilmenite lamellae as seen in nakhlites suggesting that the subsolidus cooling rate of the cooling runs was much more rapid than those of nakhlite intercumulus melts the cooling experiments reproduce the crystallization processes of pyroxenes and the compositional change of residual melt for a rapidly cooled magma such as mil 03346

the reconstruction of late quaternary antarctic sea ice distribution the use of diatoms as a proxy for sea ice the study of annual diatom transfer from the southern ocean surface to the sea floor using time series sediment traps combined with the mapping of diatom assemblages from surface sediments results in the definition of a proxy for past variations of sea ice extent the application and robustness of the proposed proxy are demonstrated by the study of late pleistocene sediment cores recovered from different environmental regimes in the southern ocean relative amounts of the sea ice indicator diatoms fragilariopsis cylindrus and fragilariopsis curta of 3 in diatom assemblages preserved in sediments are representative of the presence of seasonal winter sea ice summer sea ice occurrence is signalled by a distinct drop in biogenic sedimentation rate as a result of strongly reduced biogenic export in the presence 3 of diatom assemblage of the deep temperature diatom fragilariopsis obliquecostata the spatial and temporal distribution pattern of the sea ice proxy indicates significant sea ice variations during marine isotope stages 1 and 5 in the present antarctic zone of the southern ocean during glacial maxima the antarctic winter sea ice was extended into the present polar front zone while the antarctic summer sea ice was most probably expanded into the area of the present winter sea ice edge during the short climatic optima at the onset of interglacial periods the winter sea ice extent was distinctly reduced

earthquakes can be stress forecast in 1997 geller et al wrote earthquakes cannot be predicted because scale invariance is ubiquitous in self organized critical systems and the earth is in a state of self organized criticality where small earthquakes have some probability of cascading into a large event physically however large earthquakes can only occur if there is sufficient stress energy available for release by the specific earthquake magnitude this stress dependence can be exploited for stress forecasting by using shear wave splitting to monitor stress accumulation in the rock mass surrounding impending earthquakes the technique is arguably successful but because of the assumed unpredictability requires explicit justification before it can be generally accepted avalanches are also phenomena with self organized criticality recent experimental observations of avalanches in 2 d piles of spherical beads show that natural physical phenomena with self organized criticality such as avalanches and earthquakes can be predicted the key to predicting both earthquakes and avalanches is monitoring the matrix material not monitoring impending source zones

holocene glacier fluctuations and environmental changes in subantarctic south georgia inferred from a sediment record from a coastal inlet the subantarctic island of south georgia provides terrestrial and coastal marine records of climate variability which are crucial for the understanding of the drivers of holocene climate changes in the subantarctic region here we investigate a sediment core co1305 from a coastal inlet on south georgia using elemental lipid biomarker diatom and stable isotope data to infer changes in environmental conditions and to constrain the timing of late glacial and holocene glacier fluctuations because of the scarcity of terrestrial macrofossils and the presence of redeposited and relict organic matter in the sediments age control for the record was obtained by compound specific radiocarbon dating of mostly marine derived n c 16 fatty acids a basal till layer recovered in little jason lagoon was likely deposited during an advance of local glaciers during the antarctic cold reversal after glacier retreat an oligotrophic lake occupied the site which transitioned to a marine inlet around 8 0 0 9 ka because of relative sea level rise from 7 0 0 6 to 4 0 0 4 ka reduced vegetation coverage in the catchment as well as high siliciclastic input and deposition of ice rafted debris indicates glacier advances in the terrestrial catchment and likely in the adjacent fjord a second less extensive period of glacier advances occurred in the late holocene after 1 8 0 3 ka

glaciation of scotland during the younger dryas stadial a review considerable research effort in recent years has refined our knowledge of the landforms and sedimentary sequences generated by glaciers of the last cold episode in scotland the younger dryas and the chronology of their formation these recent advances have benefited from new technologies such as high resolution digital terrain models numerical ice sheet simulations and cosmic ray surface exposure dating this review presents a summary of recent younger dryas research in scotland particularly focusing on studies from the last two decades the findings of these investigations are compared with those of earlier workers and critically are appraised in terms of their relevance to five key aspects of younger dryas glaciation growth of the ice cap its geometry dynamics mode of decay and likely stadial climate minor differences aside the consensus view appears to favour a relatively thick but areally restricted central ice cap surrounded by satellite ice fields at its centre the ice cap was probably thickest during the first 500 years of the stadial after which it most likely thinned as the climate became increasingly arid outlet glaciers were dynamic only in marginal areas where they produced abundant moraine sequences during deglaciation but throughout much of the stadial central areas of the ice cap effected only minimal landscape modification deglaciation took place by active retreat under a rapidly warming climate overall the stadial was dominated by much colder and drier conditions than present and probably experi enced greater intra annual temperature ranges copyright 2009 john wiley sons ltd