community calcification in lizard island great barrier reef a 33 year perspective abstract measurements of community calcification g net were made during september 2008 and october 2009 on a reef flat in lizard island great barrier reef australia 33 years after the first measurements were made there by the limer expedition in 1975 in 2008 and 2009 we measured g net 61 12 and 54 13 mmol caco 3 m 2 day 1 respectively these rates are 27 49 lower than those measured during the same season in 1975 76 these rates agree well with those estimated from the measured temperature and degree of aragonite saturation using a reef calcification rate equation developed from observations in a red sea coral reef community structure surveys across the lizard island reef flat during our study using the same methods employed in 1978 showed that live coral coverage had not changed significantly 8 however it should be noted that the uncertainty in the live coral coverage estimates in this study and in 1978 were fairly large and inherent to this methodology using the reef calcification rate equation while assuming that seawater above the reef was at equilibrium with atmospheric pco 2 and given that live coral cover had not changed g net should have declined by 30 8 since the limer study as indeed observed we note however that the error in estimated g net decrease relative to the 1970 s could be much larger due to the uncertainties in the coral coverage measurements nonetheless the similarity between the predicted and the measured decrease in g net suggests that ocean acidification may be the primary cause for the lower caco 3 precipitation rate on the lizard island reef flat

sediment provenance and paleoenvironmental change in the ulleung basin of the east japan sea during the last 21 kyr despite the well reconstructed paleoceanography of the late quaternary deposits in the east japan sea es provenances of terrigenous sediments and a comprehensive interpretation of their variations since the last glacial maximum remain unclear especially in regard to the mainland china and taiwan derived matter grain size conservative trace elements rare earth elements rees nd isotope and clay mineralogy of core sediments from the ulleung basin of the es were investigated for better understanding of detrital sediment provenance and transport process and then their forcing mechanisms over the last 21 kyr geochemical mineralogical multi indices in this study showed notable three phase changes in sediment provenance which can be closely related to sea level fluctuation development of the tsushima warm current as well as intermittent influence from the east asian summer monsoon climate evolution during unit 1 21 1 8 4 kyr bp when the tsushima warm current was absent in the es the paleo changjiang and the paleo huanghe mouth might be situated close to the study area and thus mainland china could have played major role in the southwestern ulleung basin sedimentation in particular the formation of rhythmic dark colored alternation in unit 1 is possibly attributable to the pulse of paleo huanghe discharge associated with centurial to millennial scale variability in the east asian summer monsoon in unit 2 8 4 7 2 kyr bp these river mouths gradually retreated to their present positions with global sea level rise leading to decreasing terrigenous sediment supply from mainland china to the study area since 7 2 kyr bp unit 3 sedimentation in the ulleung basin should still be mainly derived from mainland china meanwhile increasing chlorite kaolinite ratio but decreasing epsilon nd value revealed that terrigenous matter from taiwan might have been limitedly transported northward to the study area by the fully evolved tsushima warm current a prominent decline in chlorite kaolinite ratio together with contrast change on epsilon nd value centered at around 2 9 kyr bp 3 3 2 4 kyr bp may have been caused by the tsushima warm current suppression possibly related to the pulleniatina minimum event popularly found in the study area and nearby seas c 2014 elsevier ltd all rights reserved

a proposed methodology for analyses of wide ranged elements in volcanic glass shards in widespread quaternary tephras the abundances of 58 elements from lithium to uranium of volcanic glass shards in 11 quaternary widespread tephras of japan and those of 4 tephras of north america have been analyzed using the laser ablation inductively coupled plasma mass spectrometry la icp ms technique the analytical values of the major components sio2 tio2 al2o3 feo mno mgo cao and k2o were systematically lower 10 than those of analyzed using electron microanalysis techniques in previous researches whereas that na2o tend to be 20 higher than those of previous researches using the electron beam microanalysis technique the higher values of na2o obtained by la icp ms may result from the absence of the na loss phenomenon associated with the electron beam analytical techniques most elements were analyzed with less than 20 of the relative standard deviations rsds whereas some trace elements such as beryllium and some transition metals exhibit higher rsds up to 120 in 5 repeated analyses on the single glass shard the la icp ms technique can be reasonably available for quantitative analyses of the major elements in volcanic glass shards in addition to the trace elements the volcanic glass can be clearly distinguished from each other by the patterns of the element abundances the element abundances and the patterns of the elements of the volcanic glass shards are helpful to more precise identification and correlation of tephra samples

origins and paleoceanographic significance of laminated muds from the ulleung basin east sea sea of japan abstract a detailed facies analysis of long piston core sediments from the ulleung basin reveals four mud facies laminated mud crudely laminated mud bioturbated mud and homogenous mud the laminated and homogeneous muds were most likely deposited from turbidity currents whereas the bioturbated and crudely laminated muds were formed by hemipelagic pelagic sedimentation under well oxygenated and poorly oxygenated bottom water conditions respectively a detailed analysis of vertical distribution of the mud facies together with a chronostratigraphic framework derived from correlative tephra layers with known eruption ages reveals paleoenvironmental changes during the late quaternary during the period between 49 and 23 ka eustatic lowering of sea level facilitated frequent slope failure resulting in repeated deposition of fine grained turbidites on the basin floor normal hemipelagic sediments were intensively bioturbated under well oxygenated bottom water conditions during the period between 23 and 13 to 11 ka deposition from turbidity currents continued but hemipelagic sediments were non bioturbated under poorly oxygenated bottom water conditions the bottom water deoxygenation is attributed to further lowering of sea level during the last glacial period and consequent intensified stratification in the water column by freshwater supply to the nearly isolated sea primary laminae preserved in the crudely laminated mud generally exhibit low compositional bimodality in backscattered electron images which suggests low surface primary productivity and presence of superficial micro bioturbation after rapid rise of sea level at 13 to 11 ka the slopes were stabilized and pelagic sedimentation has prevailed under well oxygenated bottom water conditions

relative precipitation rates of aragonite and mg calcite from seawater temperature or carbonate ion control the temperature and degree of carbonate mineral supersaturation co3 2 ion concentration of seawater are the two most likely controlling variables on the compositions of recent marine carbonate cements the relative importance of these variables is difficult to assess in nature because they have similar trends with depth 0 1500 m and latitude in modern oceans we carried out laboratory experiments to investigate the relative growth rates of calcite mg calcite and aragonite in seawater as functions of both temperature 5 25 and 37 c and of carbonate ion concentration 2 5 to 15 times supersaturated with respect to calcite the precipitation rates of aragonite relative to those of calcite increase strongly with increasing temperature and are not affected greatly by changes in saturation state at 5 c calcite precipitation rates are nearly equivalent to those of aragonite regardless of the degree of saturation at both 25 and 37 c aragonite precipitation rates are much more rapid than those of calcite up to a factor of 4 except at very low saturation states calcite compositions vary from less than 5 mol mgco3 at 5 c to 14 mol mgco3 at 37 c our results suggest that the well documented shift toward precipitation of lower mol mg calcite and the decrease in abundance of aragonite cements with increasing oceanic depth and latitude can be attributed largely to lower temperatures

boron isotope composition of the cold water coral lophelia pertusa along the norwegian margin zooming into a potential ph proxy by combining bulk and high resolution approaches abstract high latitude cold water coral reefs are particularly vulnerable to climate change due to enhanced co2 uptake in these regions to evaluate their physiological functioning and potential application as ph archives we retrieved both recent and fossil samples of lophelia pertusa along the norwegian margin from oslofjord 59 n over to trondheimsfjord sula and lopphavet 70 6 n boron isotope analyses 11b were undertaken using solution based and laser ablation multi collector inductively coupled plasma mass spectrometry mc icp ms la icp ms and secondary ion mass spectrometry sims epi fluorescence microscopy was employed to provide a rapid pre screening routine for structure specific subsampling in the coral skeleton this integrated approach enabled us to assess heterogeneities within single specimens as well as to investigate the role of local environmental influences including recent and past variations all three mass spectrometry methods show substantial differences in the 11b of the theca wall tw and the centres of calcification coc s micro bulk subsamples milled from the theca wall of modern specimens originating from different habitats but with comparable seawater ph 8 8 16 gave consistent 11b values averaging 26 7 0 2 2 n 4 while coc subsamples systematically deviated towards lower b ca by 40 and depleted 11b values minimum 22 7 0 3 2 implying a difference of at least 4 between tw and coc sims and la icp ms measurements identified much larger internal heterogeneities with maximum variation of 10 between the distinct skeletal structures minimal sims 11b values of 17 3 1 2 2 were associated with the pure coc material our findings may be interpreted in terms of the occurrence of two main but likely different biomineralisation mechanisms in l pertusa with the coc s generally exhibiting minimal ph up regulation potentially supporting the use of bicarbonate in the early stages of biomineralisation furthermore we highlight the potential utility of l pertusa for palaeo proxy studies if targeting the compositionally homogenous tw zones devoid of coc admixtures which appear to provide highly reproducible measurements

contribution of aeolian dust in japan sea sediments estimated from esr signal intensity and crystallinity of quartz 1 late quaternary hemipelagic sediments in the japan sea contain aeolian dust from east asia which potentially records past variations in the asian monsoon and the westerly jet however extracting information about aeolian dust from japan sea sediments is difficult because the sediments also contain detrital material from the japanese islands here we present a method for extracting the aeolian dust components from japan sea hemipelagic sediments using provenance analysis of different size fractions hemipelagic sediments of the japan sea can be described by a combination of two populations characterized by lognormal grain size distributions with different median grain sizes which are called the coarser 2 15 m and the finer 10 m populations we characterized these populations on the basis of provenance analyses using the electron spin resonance esr signal intensity and crystallinity of quartz the results suggest that quartz in the coarser population has been mostly supplied from northern china and siberia northeastern china by aeolian transport whereas quartz in the finer population has been dominantly supplied by rivers draining the japanese islands

dynamics of carbonate chemistry production and calcification of the florida reef tract 2009 2010 evidence for seasonal dissolution ocean acidification is projected to lower the ar of reefal waters by 0 3 0 4 units by the end of century making it more difficult for calcifying organisms to secrete calcium carbonate while at the same time making the environment more favorable for abiotic and biotic dissolution of the reefal framework there is great interest in being able to project the point in time when coral reefs will cross the tipping point between being net depositional to net erosional in terms of their carbonate budgets periodic in situ assessments of the balance between carbonate production and dissolution that spans seasonal time scales may prove useful in monitoring and formulating projections of the impact of ocean acidification on reefal carbonate production this study represents the first broad scale geochemical survey of the rates of net community production ncp and net community calcification ncc across the florida reef tract frt surveys were performed at approximately quarterly intervals in 2009 2010 across seven onshore offshore transects spanning the upper middle and lower florida keys averaged across the frt the rates of ncp and ncc were positive during the spring summer at 62 7 and 17 2 mmol m 2 d 1 respectively and negative during the fall winter at 33 6 and 7 2 mmol m 2 d 1 the most significant finding of the study was that the northernmost reef is already net erosional 1 1 0 4 kg caco3 m 2 yr 1 and midreefs to the south were net depositional on an annual basis 0 4 0 1 kg caco3 m 2 yr 1 but erosional during the fall and winter only the two southernmost reefs were net depositional year round these results indicate that parts of the frt have already crossed the tipping point for carbonate production and other parts are getting close

some numerical considerations in the geochemical analysis of distal microtephra abstract the use of late quaternary tephra horizons as isochronous markers for high resolution correlation between records is of growing importance in a number of scientific fields particular advancements have been made through the identification of microtephra deposits very distal deposits of volcanic ash invisible to the naked eye the successful correlation of ash layers and volcanic eruptions depends on the acquisition of the major element chemistries of a tephra layer derived from microprobe analyses of individual glass shards this is particularly important for microtephras where aeolian fractionation has removed much of the mineral phase of the ash deposit which often aids tephra discrimination there are however difficulties in distinguishing precisely between different eruptions of the same volcano using major element composition and this may not always be resolved by the use of trace elements given the potential of tephrochronology as a correlative tool in many disciplines it is important to resolve this difficulty one way forward is to perform more robust statistical analyses on the geochemical data as in general analyses are confined to a series of bi plots of major elements here the authors explore some of the problems associated with dealing with microprobe data generated for individual tephras and pay particular attention to the unit sum problem using a subset of data generated as part of a eurodelta project on tephra distribution in the adriatic the authors demonstrate that this problem is detectable in major element data from tephras and have consequently applied the logratio method before further analyses of the data it is demonstrated that the use of logratios combined with discriminant functions analysis provides a more robust assessment of likely chemical correlations between tephras and are superior to the use of bi plots alone and obviate the need for any data normalization a particular point of contention between tephrochronologists

magnetic susceptibility of soils along a lithotoposequence in southeast iran abstract magnetic susceptibility is a simple and quick technique to determine soil properties and to describe soil forming processes knowledge about factors affecting data helps better interpretation magnetic susceptibility of soils along a lithotoposequence was studied in this research in order to investigate the effects of soil forming factors parent material and relief and processes on the content and its vertical distribution the study area is a transect from jiroft to kahnooj area south kerman province iran rock pediment mantled pediment inselberg alluvial fan alluvial plain and flood plain landforms with igneous parent materials gabbro diorite and granite were selected in the area thirteen representative pedons on different geomorphic positions were studied low frequency lf values ranged from 193 1 10 8 m3 kg 1 to 2704 2 10 8 m3 kg 1 in studied soils and decreased with increasing diamagnetic material contents mean lf values in soils formed on gabbro diorite and granite parent rock were 1700 10 8 m3 kg 1 515 22 10 8 m3 kg 1 and 352 53 10 8 m3 kg 1 respectively frequency dependent of soils in the range of 0 06 to 1 05 showed that coarse multi domain grains inherited from igneous parent material were the main source of lf in the area under study both increasing and decreasing trends of lf with depth were observed decreasing trend of lf with depth was due to illuviation of diamagnetic material into subsurface layers on the other hand increasing lf with depth was attributed to the primary ferrimagnetic material inherited from igneous parent material alluvial plain 320 44 10 8 m3 kg 1 and mantled pediment 328 50 10 8 m3 kg 1 showed low values of lf due to high amounts of soluble salts anhydrite and calcium carbonate investigated in these geomorphic positions a positive significant relationship r2 0 018 r 0 27 p

stratigraphy of the anthropocene the anthropocene an informal term used to signal the impact of collective human activity on biological physical and chemical processes on the earth system is assessed using stratigraphic criteria it is complex in time space and process and may be considered in terms of the scale relative timing duration and novelty of its various phenomena the lithostratigraphic signal includes both direct components such as urban constructions and man made deposits and indirect ones such as sediment flux changes already widespread these are producing a significant event layer locally with considerable long term preservation potential chemostratigraphic signals include new organic compounds but are likely to be dominated by the effects of co2 release particularly via acidification in the marine realm and man made radionuclides the sequence stratigraphic signal is negligible to date but may become geologically significant over centennial millennial time scales the rapidly growing biostratigraphic signal includes geologically novel aspects the scale of globally transferred species and geologically will have permanent effects

widespread submarine tephras around japan petrographic and chemical properties abstract in deep sea sediments around the japanese islands tephra layers are frequently recognized and some tephras can be identified by petrographic and chemical features and correlated to source volcanoes of both japan and korea most tephras distributed over more than several hundred kilometers from the source volcanoes were presumably carried away by the dominant westerly wind six characteristic marker tephras in deep sea sediments can be identified and correlated according to their distribution and grain size petrography and chemistry they play an important role in compiling the late quaternary chronology of the deep sea sediments distributed around the japanese islands petrographic and geochemical studies reveal that the refractive index of volcanic glass shards in tephras is controlled by the amount of total transition metal oxides rather than the amount of sio 2 we propose a new equation relating refractive index to glass shard chemistry

identification and significance of a visible basalt rich vedde ash layer in a late glacial sequence on the isle of skye inner hebrides scotland this paper reports the discovery of a visible tephra horizon of late glacial age from the site of loch ashik in the isle of skye the inner hebrides scotland although the tephra shards have a bimodal geochemical composition identical to that of the vedde ash a well known marker horizon within late glacial sequences the horizon at ashik is dominated by basaltic shards and devitrified tephra shards giving the layer its characteristic black colour only rhyolitic shards have previously been reported from vedde ash horizons in the british isles this new evidence raises some important questions about the factors that govern the distribution and accumulation of basaltic tephra and about the methods used to detect ash shards in basins distal to centres of volcanic activity copyright 2001 john wiley sons ltd

magnetic mineral assemblages in soils and paleosols as the basis for paleoprecipitation proxies a review of magnetic methods and challenges abstract magnetic iron oxide minerals principally magnetite maghemite hematite and goethite are formed in well drained soils in response to a suite of physical chemical and biological factors despite a wide range of complexity in the pedogenic processes that lead to magnetic mineral formation dissolution and transformation there are well documented empirical relationships between various magnetic mineral assemblages in soils with environmental and climatic conditions recently there has been an increase in the number of quantitative magnetic paleoprecipitation proxies that have been developed and there is great potential for magnetic methods to be used in the geologic record to develop reconstructions of past climates magnetic paleoprecipitation proxies have been widely utilized in quaternary or younger loess paleosol systems however they have yet to be utilized in the pre quaternary fossil record future studies of magnetic mineralogy of soils and paleosols should aim to explore non loessic modern soils and pre quaternary paleosols with more focus on understanding the interaction between magnetic mineral assemblages and soil moisture applications of existing and novel magnetic paleoprecipitation proxies in the fossil record should prove to be a valuable resource for paleoclimatologists

potential influence of sea cucumbers on coral reef caco3 budget a case study at one tree reef to endure coral reefs must accumulate caco3 at a rate greater or equal than the sum of mechanically biologically and chemically mediated erosion rates we investigated the potential role of holothurians on the caco3 balance of a coral reef these deposit feeders process carbonate sand and rubble through their digestive tract and dissolve caco3 as part of their digestive process in aquarium incubations with stichopus herrmanni and holothuria leucospilota total alkalinity increased by 97 13 and 47 7 mol kg 1 respectively this increase was due to caco3 dissolution 81 13 and 34 6 mol kg 1 and ammonia secretion 16 2 and 14 2 mol kg 1 respectively for these species surveys conducted at a long term monitoring site of community calcification dk13 on one tree reef indicated that the density of sea cucumbers was approximately 1 individual m 2 we used these data and data from surveys at shark alley to estimate the dissolution of caco3 by the sea cucumbers at both sites at dk13 the sea cucumber population was estimated to be responsible for nearly 50 of the nighttime caco3 dissolution while in shark alley for most of the nighttime dissolution thus in a healthy reef bioeroders dissolution of caco3 sediment appears to be an important component of the natural caco3 turnover and a substantial source of alkalinity as well this additional alkalinity could partially buffer changes in seawater ph associated with increasing atmospheric co2 locally thus reducing the impact of ocean acidification on coral growth

chemical composition of a drilled core of lake biwa in japan and implications for source changes during the past 430 000 years abstract neutron activation analysis was performed on sediments taken from the 250 m thick sediment bed of lake biwa which is composed entirely of lacustrine clay and records paleo environmental change over the past 430 000 years a comparison is made between the geochemical compositions of cores from the center of lake biwa and lacustrine surface and terrestrial sediments from around lake biwa to estimate past changes in sediment sources time series of th sc ratios are synchronized with glacial interglacial climatic change and also correlated with the reported aeolian quartz flux data th sc ratios during the 18o stages 1 5 7 9 and 11 are approximately 1 1 1 2 whereas th sc ratios during the 18o stages 2 4 6 8 and 10 are approximately 1 0 1 1 the possibility of a contribution from the mafic area in the northwestern shore of lake biwa which has low th sc ratios ca 0 8 is excluded by the ti al ratio data as aeolian dust flux to the downwind area from the asian desert area is higher during glacial times this data suggests that aeolian dust reaching japan has an unexpectedly low th sc ratio of source material and or that there was a large shift in the amount of dust flux this assumption remains to be tested by future studies th sc ratios apparently lag ca 5000 years behind the marine 18o record during the stage 1 2 3 4 and 5 6 transitions which coincides with the aeolian quartz flux variation continuous increase of hf contents from ca 200 000 years bp could be mainly related to upheaval of the hf rich and high th sc ratio granite block on the west shore of drilling site by active fault movement the variations in delivery of high th sc granitic debris has damped the oscillation between th sc ratios of sediments and aeolian dust flux during oxygen isotopic stages 2 3 both the intermittent increase of na contents from ca 430 000 years bp to present and the abrupt increase of na content at ca 140 000 years bp are probably due to the subsidence of the northern basin as the result of tectonic movement around lake biwa

identification and correlation of visible tephras in the lake suigetsu sg06 sedimentary archive japan chronostratigraphic markers for synchronising of east asian west pacific palaeoclimatic records across the last 150 ka abstract the lake suigetsu sg06 sedimentary archive from honshu island central japan provides a high resolution palaeoenvironmental record including a detailed record of explosive volcanism from japan and south korea thirty visible tephra are recorded within the 73 m long sg06 core which spans the last 150 ka here we describe and characterise these tephras based on major element glass composition which is useful for the identification and correlation of these tephras and the age models of the records in which they are found utilising the large number of radiocarbon measurements n 600 from terrestrial plant macrofossils in the lake suigetsu sg06 record we are able to provide precise and accurate ages for the tephras from eruptions within the last 50 ka glass compositional data of some of the largest eruptions from japan k ah at aso 4 aso a aso d and ata sampled at proximal outcrops are also presented these data show that the major element glass chemistry is distinctive for many of the visible sg06 tephra units and allows some of the layers to be correlated to known eruptions from volcanoes in japan and south korea namely k ah sg06 0967 u oki sg06 1288 at sg06 2650 aso 4 sg06 4963 sg06 4979 k tz sg06 5181 aso abcd sg06 5287 and ata sg06 5181 the following ages were obtained for the sg06 tephra units 3 966 4 064 cal ka bp 95 4 probability range for the sg06 0588 tephra 10 242 10 329 cal ka bp 95 4 probability range for sg06 1293 19 487 112 sg06 2012 ka bp 2 for sg06 1965 28 425 194 sg06 2012 ka bp 2 for sg06 2504 28 848 196 sg06 2012 ka bp 2 for sg06 2534 29 765 190 sg06 2012 ka bp 2 for sg06 2601 29 775 191 sg06 2012 ka bp 2 for sg06 2602 43 713 156 sg06 2012 ka bp 2 for sg06 3485 46 364 202 sg06 2012 ka bp 2 for sg06 3668 49 974 337 sg06 2012 ka bp 2 for sg06 3912 50 929 378 sg06 2012 ka bp 2 for sg06 3974 and improved ages for two of the most important tephra markers across japan the k ah 7 165 7 303 cal ka bp at 95 4 probability range sg06 0967 and at tephra 30 009 189 sg06 2012 ka bp at 2 sg06 2650

decadal changes in the aragonite and calcite saturation state of the pacific ocean 1 based on measurements from the woce jgofs global co2 survey the clivar co2 repeat hydrography program and the canadian line p survey we have observed an average decrease of 0 34 yr 1 in the saturation state of surface seawater in the pacific ocean with respect to aragonite and calcite the upward migrations of the aragonite and calcite saturation horizons averaging about 1 to 2 m yr 1 are the direct result of the uptake of anthropogenic co2 by the oceans and regional changes in circulation and biogeochemical processes the shoaling of the saturation horizon is regionally variable with more rapid shoaling in the south pacific where there is a larger uptake of anthropogenic co2 in some locations particularly in the north pacific subtropical gyre and in the california current the decadal changes in circulation can be the dominant factor in controlling the migration of the saturation horizon if co2 emissions continue as projected over the rest of this century the resulting changes in the marine carbonate system would mean that many coral reef systems in the pacific would no longer be able to sustain a sufficiently high rate of calcification to maintain the viability of these ecosystems as a whole and these changes perhaps could seriously impact the thousands of marine species that depend on them for survival

magnetic imprints of pedogenesis in planosols and stagnic alisol from bulgaria iron in its diverse forms in soils is an important indicator of a number of past and or ongoing environmental processes iron oxide mineralogy pertinent to a particular soil type could be obtained with high resolution using magnetic methods planosols are a particular soil type characterized by surface water logging leading to development of great textural differentiation with depth this study presents magnetic investigation on three planosols and a stagnic alisol from bulgaria combined with conventional chemical extraction methods oxalate citrate dithionite and soil property characterization ph grain size fractions and organic carbon content extensive magnetic analyses on high resolution sampled depth profiles have been done for determination of iron oxyhydr oxide minerals their stability and variations of effective magnetic grain size with depth zones of intensive iron oxides dissolution the topmost soil horizons are magnetically depleted in the content of strongly magnetic minerals but the paramagnetic content detected through the ratio 77 293 is enhanced accordingly bleached eluvial horizons however contain stable crystalline magnetite maghemite fraction albeit in a trace amounts we ascribe this to the processes of lessivage and translocation of magnetite maghemite from the topmost humus horizon the main results on iron oxide mineralogy suggest that thin humus horizons are enriched with pedogenic maghemite thermal behavior of magnetic susceptibility suggests that ferrihydrite is present in humus and eluvial horizons of all profiles in illuvial horizons of planosols the common mineral is lepidocrocite while in alisol al substituted hematite planosols and stagnic alisol contain both poorly crystalline and well crystalline iron oxides increasing precipitation and weathering leads to higher proportion of well crystalline pedogenic phases in the alisol profile

late pleistocene holocene paleoenvironmental changes inferred from the diatom record of the ulleung basin east sea sea of japan abstract the diatom floral record from two piston cores 00ghp 01 and 00ghp 07 taken from the southwestern margin of the ulleung basin east sea sea of japan reveals a series of well defined changes in glacio eustatic sea level and paleoceanographic conditions during the late pleistocene holocene six assemblage zones and two barren zones in 00ghp 01 and four assemblage zones in 00ghp 07 are erected respectively on the basis of frequency of variations in and occurrences of biostratigraphically significant diatom species all assemblage zones have been strongly influenced by the tsushima warm current twc the twc has an important affect on controlling the distribution and composition of diatom flora which in turn reveal the history of the twc in this area the distribution pattern of diatoms in the diatom assemblages reveals sea surface temperature and salinity affected by the sediments type and terrigenous material input diatom temperature td values show that the site of 00ghp 01 in the ulleung basin has been influenced by a relatively enhanced twc twice during the deposition of lowermost and uppermost intervals a relatively weak twc was recorded in the middle interval since the latest pleistocene the diatom assemblages of 00ghp 07 represent an apparently continuous late quaternary record spanning the last glacial maximum bolling allerod younger dyras and holocene high abundance of a low salinity coastal water diatom paralia sulcata may reflect the influx of the east china sea water through the korean strait to the east sea sea of japan during the last glacial maximum the sea level was low enough that selected basin with shallow sills along the margin of the east sea sea of japan became isolated from the pacific ocean salinity also decreased due to increased freshwater input from rivers draining the surrounding lands the density stratified water column may have prevented vertical mixing and resulted in anoxic bottom water conditions

age of the skp i and skp ii tephras from the southern east sea japan sea implications for interstadial events recorded in sediment from marine isotope stages 3 and 4 abstract the ages of two newly identified tephras in marine oxygen isotope stages mis 3 and 4 from the southern east sea japan sea es js have been determined analysis of chemical composition grain size distribution sediment texture and pumice micromorphology of material from 24 marine sediment cores was combined with a high resolution age model established for core md01 2407 the marine sedimentary record of the es js is characterized by a drastic millennium scale variation in paleoceanographic conditions that is closely linked to dansgaard oeschger d o events the chemical composition of the two tephras which are stratigraphically located between previously dated at 29 24 ka and aso 4 88 ka tephras varies from phonolitic to trachytic 57 11 62 87 wt sio2 with 5 03 6 81 wt k2o and 6 32 9 87 wt na2o they exhibit a conspicuously bimodal grain size distribution and have randomly oriented vesicles with thick walls the dispersal patterns of these tephras differ markedly from that of the u oki tephra which is originated from a subaerial eruption on ulleung island the two newly identified tephras named skp i and skp ii reach their maximum thickness and grain size at a location near the south korea plateau skp an age model for a core from the oki ridge md01 2407 yields eruptive ages of about 40 41 ka for the skp i tephra and about 60 61 ka for the skp ii tephra a comparison of sediment lightness l with gisp2 oxygen isotope data suggests that the skp i tephra is stratigraphically between d o interstadial is 9 and 10 and the skp ii tephra is between d o is 17 and 18 the skp i and skp ii tephras are equivalent to the u ym tephra described by arai et al arai f oba t kitazato h horibe y machida h 1981 late quaternary tephrochronology and paleo oceanography of the sediments of the japan sea quat res daiyonki kenkyu 20 209 230 in japanese with english abstr and that described by ikehara et al ikehara k kikkawa k chun j h 2004 origin and correlation of three tephras that erupted during oxygen isotope stage 3 found in cores from the yamato basin central japan sea quat res daiyonki kenkyu 43 201 212 in japanese with english abstr respectively they not only provide marker horizons within the stratigraphic interval corresponding to mis 3 and 4 but also can be useful to identify d o events for marine cores from the southern part of the es js

abrupt increase in greenland snow accumulation at the end of the younger dryas event the warming at the end of the last glaciation was characterized by a series of abrupt returns to glacial climate the best known of which is the younger dryas event1 despite much study of the causes of this event and the mechanisms by which it ended many questions remain unresolved1 oxygen isotope data from greenland ice cores2 4 suggest that the younger dryas ended abruptly over a period of about 50 years dust concentrations2 4 in these cores show an even more rapid transition 20 years this extremely short timescale places severe constraints on the mechanisms underlying the transition but dust concentrations can reflect subtle changes in atmospheric circulation which need not be associated with a large change in climate here we present results from a new greenland ice core gisp2 showing that snow accumulation doubled rapidly from the younger dryas event to the subsequent preboreal interval possibly in one to three years we also find that the accumulation rate change from the oldest dryas to the bo11ing allerod warm period was large and abrupt the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the north atlantic climate system

influence of variable rates of neritic carbonate deposition on atmospheric carbon dioxide and pelagic sediments short term imbalances in the global cycle of shallow water calcium carbonate deposition and dissolution may be responsible for much of the observed pleistocene change in atmospheric carbon dioxide content however any proposed changes in the alkalinity balance of the ocean must be reconciled with the sedimentary record of deep sea carbonates the possible magnitude of the effect of shallow water carbonate deposition on the dissolution of pelagic carbonate can be tested using numerical simulations of the global carbon cycle boundary conditions can be defined by using extant shallow water carbonate accumulation data and pelagic carbonate deposition dissolution data on timescales of thousands of years carbonate deposition versus dissolution is rarely out of equilibrium by more than 1 5 x 10 13 mole yr 1 results indicate that the carbonate chemistry of the ocean is rarely at equilibrium on timescales less than 10 ka this disequilibrium is probably due to sea level induced changes in shallow water calcium carbonate deposition dissolution an interpretation that does not conflict with pelagic sedimentary data from the central pacific

magnetic fingerprint of southern portuguese speleothems and implications for paleomagnetism and environmental magnetism environmental magnetism of speleothems is still in its early stage of development here we report on our investigation of the environmental and paleomagnetic information that has been recorded in speleothems and what are the factors that control its preservation and reliability to address these issues we used a multidisciplinary approach including rock magnetism petrography scanning electron microscopy stable carbon and oxygen isotope compositions and major and trace element concentrations we applied this to a set of samples from different stages of speleothem evolution present day dripwater glass plates a weathered stalactite a fresh stalagmite cave sediments and terra rossa soils these samples come from the penico and excentricas caves located in two distinct aquifers of the algarve region south portugal our results show that the main magnetic carriers of the speleothems under study are primary detrital and consist of maghemite and magnetite similarities in coercivity and temperature dependence of the studied set of samples suggest that iron oxides are inherited from the terra rossa soils that cap the cave and were transported to the speleothems by dripwater hence they represent a regional environmental signature interestingly a stable and probably detrital remanent magnetization could be isolated in the fresh stalagmite whereas the weathered stalactite yielded chaotic magnetic directions and very low remanent intensities we propose that these low intensities can be the result from i different remanence acquisition mechanisms between stalagmite and stalactite and or ii iron dissolution by fungal activity we also suggest that magnetic properties and color and the content in detrital elements in the fresh speleothem inform about environmental processes acting on the interface of rock soil atmosphere while oxygen isotope composition and alkaline earth element concentrations inform about calcite water interaction processes these results provide a better understanding of how environmental information is recorded in speleothems and what the factors are that control the reliability of the paleomagnetic and paleo environmental signal

extensive ash falls in and around the sea of japan from large late quaternary eruptions abstract five widespread ashes of late quaternary age have been recognized on land and also in deep sea sediments in and around the sea of japan all are favorable for determining the magnitude and type of the great eruptions and for establishing a quaternary chronology around japan accurate determination of refractive indices of volcanic glass shards and phenocrysts together with chemical data have enabled successful characterization of the tephra layers and correlation between land and sea of the five tephras two are alkalic and are the products of major eruptions of two korean volcanoes the baegdusan tomakomai ash b tm and the ulreung oki ash u oki the b tm ash is recognized at the top of most cores in the northern part of the sea of japan and also on hokkaido and the northern part of honshu where a reliable archeological age is given around the 11th century the u oki ash occurs between the kikai akahoya and aira tn ashes in cores from adjacent to the ulreung do to central honshu where three radiocarbon ages of around 9300 yr b p were obtained the other three tephras are subalkalic and are correlated with large scale eruptions producing voluminous pyroclastic flows and calderas in kyushu the kikai akahoya k ah aira tn at and aso 4 ashes the former two have been well described already but their fallout areas are partly revised in this manuscript the at ash is the most prominent marker recognized not only on land of japan but also in cores from the whole area of the sea of japan and part of the pacific ocean the airfall aso 4 ash simultaneous with the aso 4 pyroclastic flow eruption is also described it mantles very extensive areas and serves as an important time marker about 70 000 years ago

morphological characterisation of reef types in torres strait and an assessment of their carbonate production coral reefs represent major accumulations of calcium carbonate caco3 the particularly labyrinthine network of reefs in torres strait north of the great barrier reef gbr has been examined in order to estimate their gross caco3 productivity the approach involved a two step procedure first characterising and classifying the morphology of reefs based on a classification scheme widely employed on the gbr and then estimating gross caco3 productivity rates across the region using a regional census based approach this was undertaken by independently verifying published rates of coral reef community gross production for use in torres strait based on site specific ecological and morphological data a total of 606 reef platforms were mapped and classified using classification trees despite the complexity of the maze of reefs in torres strait there are broad morphological similarities with reefs in the gbr the spatial distribution and dimensions of reef types across both regions are underpinned by similar geological processes sea level history in the holocene and exposure to the same wind wave energetic regime resulting in comparable geomorphic zonation however the presence of strong tidal currents flowing through torres strait and the relatively shallow and narrow dimensions of the shelf exert a control on local morphology and spatial distribution of the reef platforms a total amount of 8 7million tonnes of caco3 per year at an average rate of 3 7kg caco3m 2yr 1 g were estimated for the studied area extrapolated production rates based on detailed and regional census based approaches for geomorphic zones across torres strait were comparable to those reported elsewhere particularly values for the gbr based on alkalinity reduction methods however differences in mapping methodologies and the impact of reduced calcification due to global trends in coral reef ecological decline and changing oceanic physical conditions warrant further research the novel method proposed in this study to characterise the geomorphology of reef types based on classification trees provides an objective and repeatable data driven approach that combined with regional census based approaches has the potential to be adapted and transferred to different coral reef regions depicting a more accurate picture of interactions between reef ecology and geomorphology

tephra layers in late quaternary sediments of the central adriatic sea abstract magnetic susceptibility curves of ten cores collected in the western adriatic shelf and in the mid adriatic deep allowed us to recognize thirty tephra layers whose age based on physical and biostratigraphic data encompass a time interval ranging from less than 70 ka to the present chemical features of the tephra defined by sem eds analyses performed on glass shards indicate alkaline affinity mainly with k na 1 and trachytic compositions with two minor benmoreitic and phonolitic groups these characteristics are consistent with campanian and subordinate etnean provenances because of chemical and age constraints the glass shards can be referred to six tephra layers already described in the literature such as c20 c14 citara ischia c10 campanian ignimbrite c2 nyt neapolitan yellow tuff ams pf agnano monte spina phlegrean fields from campanian area and y1 from etna volcano indicating an age ranging from about 70 to 4 ka ams pf and c2 nyt dated 4 4 and 12 3 ka respectively are the most widespread tephra beds in the study cores the occurrence of ams pf never recorded in marine sequences up to now represents a very good marker for holocene adriatic sediments c2 nyt already recorded in the central tyrrhenian sea in lacustrine sediments from southern italy and in the campanian area is a good stratigraphic marker for inter sea and sea land correlations y1 tephra dated 14 2 ka also occurs in on land sediments of central italy and in marine sediments from the tyrrhenian and ionian seas it now represents one of the most widespread stratigraphic markers in the central mediterranean region

tephras and new zealand archaeology establishing an accurate date for earliest polynesian settlement in new zealand is essential for understanding patterns of settlement and associated enviromental impacts and the processes and rates of cultural change in eastern polynesia tephra deposits from five volcanic centres together with exotic sea rafted pumice provide isochronous constraints on the timing of earliest settlement and human impacts in northern new zealand a local basaltic tephra from rangitoto island auckland and locally distributed andesitic tephras from egmont volcano directly date human occupation toc ad 1400 1450 distal andesitic tephras tufa trig formation from mt ruapehu tongariro volcanic centre help constrain the timing of earliest anthropogenic deforestation signals in hawke s bay sea rafted loisels pumice s although of uncertain stratigraphic reliability in places overlies cultural remains that can be no younger thanc ad 1350 along the east coast north island the regionally extensive rhyolitic kaharoa tephra which erupted from okataina volcano between c ad 1300 1390 is the critical settlement layer datum for dating prehistory in the north island no human artefacts are recorded beneath it and the earliest inferred environmental impacts by humans are dated to c ad 1280 just prior to its deposition this maximum date matches the earliest radiocarbon dates derived for both settlement and human impacts from archaeological and natural sites c ad 1250 and implies that the onset of deforestation was essentially contemporaneous with initial settlement the widespread rhyolitic taupo tephra which erupted from taupo volcanoc ad 200 provides an isochronous benchmark well before earliest settlement the tephra may coincide approximately with a putative earlier transient contact in new zealand based on pacific rat bone rattus exulans dates more precise calendrical dates on the tephras via dendrochronology or ice core records or other dating methods would help refine assessment of the timing of earliest settlement while extending the distributional range of critical tephra layers through application of crypto tephra analysis could lead to a greater understanding of settlement patterns

magnetite originating from bonfires in a brazilian prehistoric anthrosol a micro raman approach abstract soils within archaeological sites may show magnetic properties due to the presence of magnetic minerals such as magnetite and maghemite which form during deposition of the soil or due to local fires the similarities in the crystallographic structures of magnetite and maghemite lead to difficulties in the identification of these mineral phases this work aims to study the genesis of fe nodules at an archaeological site in a cave in quartzite with a very low fe content and no spinel group minerals the guiding hypotheses of the research are as follows i the abundant fe nodules in all the studied stratigraphic layers are of pedogenic origin and were generated by local bonfires and ii these fe nodules are composed of magnetite maghemite and hematite and the conversion of magnetite to maghemite indicates pedogenic processes micromorphological analysis and raman spectroscopy were used for mineral phase determination the results confirm the in situ pedological nature of the fe nodules associated with anthropogenic fires in the cave

revisiting the origin of organic matter and depositional environment of sediment in the central ulleung basin east sea since the late quaternary abstract by analyzing sedimentary geochemical data from three piston cores in the central ulleung basin east sea we discuss the origin of organic matter and the depositional environment of sediments from marine isotope stage mis 3 to 1 downcore profiles show that the values of toc total organic carbon tn total nitrogen and 13corg are the lowest values during mis 2 and the highest during mis 1 the relationship between toc tn and 13corg shows that most data fall in the region of the marine algae irrespective of mis stage which illustrates that the organic matter has been predominantly produced by a marine source rather than by a terrestrial source since the late quaternary however depleted 13corg values are discretely observed during mis 2 and mis 3 particularly in dark laminated mud dlm which appears to reflect the influence of episodic event by the east asian monsoon rather than the organic matter source changing by lower sea level previous sedimentological studies in the ulleung basin reported that the depositional environment of sediment in mis 2 was more reducing than during mis 1 and mis 3 but our geochemical data do not support this interpretation the abundance of most redox sensitive trace elements e g mn v u and mo has not significantly varied from mis 3 to mis 1 in addition the ratios of redox sensitive trace elements e g ni co v cr v ni u th and v v ni indicate a predominantly oxic or suboxic environment the bottom water condition was similarly oxic to suboxic during times of sediment deposition since the late quaternary the sedimentary layers containing tephra and foraminiferal shell fragments illustrate abnormal element al ratios suggesting that these allochthonous sediment sources are one of important factors controlling the geochemical composition of sediments in the ulleung basin

mineral magnetic properties of chinese paddy soils and its pedogenic implications abstract magnetic susceptibility ms of paddy soils hydragric anthrosols and their corresponding dryland soils formed on the same parent materials in zhejiang province of eastern china were measured in order to understand better magnetic profile discrimination and pedogenic magnetic minerals in paddy soils magnetic measurements showed that the ms values of paddy soils were much lower than those of dryland soils formed on the same parent materials the higher the ms value of the original dryland soil is the more remarkable the decrease in the ms value is when the soil is put under rice cultivation gleyed paddy soils exhibited very low ms value

lithological factors affecting magnetic susceptibility of subtropical soils zhejiang province china abstract magnetic susceptibility was measured on subtropical soils formed on a range of parent materials in zhejiang province china to demonstrate the influence of parent material lithologies on the amount and vertical distribution of in the soils we found that the values of soils vary by up to two orders of magnitude with their parent material lithologies soils formed on igneous rocks with high values showed high absolute and distinctly decreased compared with values of parent materials the values of soils formed on basalt andesite and granodiorite were 250 10 8 m 3 kg 1 the values of soils formed on granite and other neutral and acid igneous rocks ranged from 50 10 8 to 120 10 8 m 3 kg 1 in most of the soils formed on sedimentary rocks enhancement in upper horizons of soils was found compared with parent material this enhancement was believed to be pedogenic formation of superparamagnetic sp stable single domain ssd magnetic grains which are characterized by high values of frequency dependent susceptibility fd and anhysteretic remanent magnetization arm soils formed on sedimentary rocks with a very low initial and iron content showed a low value throughout the profile it was found that there is a highly significant relationship between the values of soils and their dithionite citrate bicarbonate solution dcb soluble iron contents fe d the values of soils in chronosequences formed on alluvium and two marine deposits increased as soils became older it is suggested that the values can be used as a tool for determining the relative age in chronosequence studies

simulated effect of deep sea sedimentation and terrestrial weathering on projections of ocean acidification projections of ocean acidification have often been based on ocean carbon cycle models that do not represent deep sea sedimentation and terrestrial weathering here we use an earth system model of intermediate complexity to quantify the effect of sedimentation and weathering on projections of ocean acidification under an intensive co2 emission scenario that releases 5000 pgc after year 2000 in our simulations atmospheric co2 reaches a peak concentration of 2123 ppm near year 2300 with a maximum reduction in surface ph of 0 8 consideration of deep sea sedimentation and terrestrial weathering has negligible effect on these peak changes only after several millenniums sedimentation and weathering feedbacks substantially affect projected ocean acidification ten thousand years from today in the constant alkalinity simulation surface ph is reduced by 0 7 with 95 of the polar oceans undersaturated with respect to calcite and no ocean has a calcite saturation horizon csh that is deeper than 1000 m with the consideration of sediment feedback alone surface ph is reduced by 0 5 with 35 of the polar oceans experiencing calcite undersaturation and 8 global ocean has a csh deeper than 1000 m with the addition of weathering feedback depending on the weathering parameterizations surface ph is reduced by 0 2 0 4 with no polar oceans experiencing calcite undersaturation and 30 80 ocean has a csh that is deeper than 1000 m our results indicate that deep sea sedimentation and terrestrial weathering play an important role in long term ocean acidification but have little effect on mitigating ocean acidification in the coming centuries this article is protected by copyright all rights reserved

using magnetic susceptibility to facilitate more rapid reproducible and precise delineation of hydric soils in the midwestern usa abstract standard field indicators currently used for hydric soil delineations usda nrcs 1998 field indicators of hydric soils in the united states version 4 0 in g w hurt et al ed united states department of agriculture nrcs fort worth tx are useful but in some cases they can be subjective difficult to recognize or time consuming to assess magnetic susceptibility ms measurements acquired rapidly in the field with a portable meter have great potential to help soil scientists delineate and map areas of hydric soils more precisely and objectively at five sites in illinois from 5 to 15 ha in area with contrasting soil types and glacial histories the ms values of surface soils were measured along transects and afterwards mapped and contoured the ms values were found to be consistently higher in well drained soils and lower in hydric soils reflecting anaerobic deterioration of both detrital magnetite and soil formed ferrimagnetics at each site volumetric ms values were statistically compared to field indicators to determine a critical ms value for hydric soil delineation such critical values range between 22 10 5 and 33 10 5 si in silty loessal or alluvial soils in illinois but are as high as 61 10 5 si at a site with fine sandy soil a higher magnetite content and slower dissolution rate in sandy soils may explain the difference among sites with silty parent material the lowest critical value 22 10 5 si occurs in soil with low ph 4 5 5 5 since acidic conditions are less favorable to ferrimagnetic mineral neoformation and enhance magnetite dissolution because of their sensitivity to parent material properties and soil ph critical ms values must be determined on a site specific basis the ms of studied soil samples 0 5 cm depth is mainly controlled by neoformed ultrafine ferrimagnetics and detrital magnetite concentrations with a minor contribution from anthropogenic fly ash neoformed ferrimagnetics are present in all samples but based on high fd 5 to 10 are most prevalent in high ph mollisols of northeastern illinois scanning electron microscope images display significantly more detrital magnetite alteration in hydric soils substantiating that reductive dissolution of magnetite aided by microorganisms is a primary cause for lower ms fly ash comprises 8 50 of the 5 m strongly magnetic particles and typically accounts for 5 15 of the total ms signal the proportion of fly ash in 5 m strongly magnetic fractions is greater in hydric soils because of lower natural magnetite contents possibly combined with historical topsoil accumulation in lower landscapes magnetic fly ash particles are also more altered in low ms soils implying that significant magnetite dissolution can occur in less than 150 years

rerewhakaaitu tephra a land sea marker for the last termination in new zealand with implications for global climate change abstract the rerewhakaaiutu tephra erupted from okataina volcanic centre north island new zealand at 14 700 95 14 c yr bp ca 17 600 cal yr bp at a time of rapid re organisation of earth s climate system at the end of the last glacial termination i it provides a distinctive isochron in a range of different environments in north island and in adjacent south pacific ocean sediments terrestrial evidence based on fluvial aggradation and downcutting relationships loess accumulation rates palaeovegetation patterns and buried soil development and mineralogy shows that marked amelioration of climate occurred shortly before the rerewhakaaitu tephra was deposited similarly marine evidence from around this time shows major changes in accumulation rates of sediment and aeolian quartz and in the abundance of various marine organisms while foraminiferal oxygen and carbon isotope records indicate that the arrival of the glacial meltwater signal occurred close to or just after the deposition of the rerewhakaaitu tephra these changes are discussed in relation to controls on climate by oceanic and atmospheric mechanisms the re organisation of climate commencing at ca 15 000 14 500 14 c yr bp ca 18 000 17 400 cal yr bp is detected elsewhere in the southern hemisphere and evidently was linked to orbitally forced warming which is thought to have initiated ice retreat in both hemispheres

millennial timescale resolution of rhyolite magma recharge at tarawera volcano insights from quartz chemistry and melt inclusions most rhyolite eruption episodes of tarawera volcano have emitted several physiochemically distinct magma batches 1 10 km3 these episodes were separated on a millennial timescale the magma batches were relatively homogeneous in temperature and composition at pumice scale 4 cm but experienced isolated crystallisation histories at the sub cm scale matrix glasses have trace element compositions sr ba rb that vary by factors up to 2 5 indicating incomplete mixing of separate melts some quartz hosted melt inclusions are depleted in compatible trace elements sr ti ba compared to enclosing matrix glasses this could reflect re melting of felsic crystals deeper in the crystal pile individual quartz crystals display a variety of cathodoluminescence brightness and ti zoning patterns including rapid changes in melt chemistry and or temperature 50 100 c and point to multi cycle crystallisation histories the tarawera magma system consisted of a crystal rich mass containing waxing and waning melt pockets that were periodically recharged by silicic melts driven by basaltic intrusion

cryptotephra detection using high resolution trace element analysis of holocene marine sediments southwest japan abstract detection techniques for invisible tephra known as cryptotephra have been exploited to construct precise and high resolution correlations for a broad range of sedimentary sequences we demonstrate that continuous trace element profiles are an effective means for detecting probable positions of distal cryptotephra in holocene hemipelagic sediments instrumental neutron activation analyses were performed on specimens of bulk sediments from five piston and gravity cores water depths 300 1500 m taken from the southern japan east sea the down core variations in the ta sc ratio identify the positions of one to three alkaline cryptotephra in four of these cores the cr sc profiles show the position of one rhyolitic cryptotephra in three of the cores the existence of tephra derived components glass crystals was confirmed by microscopic observation sem epma analysis and refractive index measurement on grains extracted from these layers based on microscopic observation and the stratigraphic correlations between cores we identified eruption ages of the cryptotephras at 6 3 7 5 and 9 3 14 c kyr bp and two source volcanoes around 800 and 400 km from the study area the tephra layers visible to the naked eye contained volcanic grains coarser than 200 m and the alkaline and rhyolitic tephra component comprised 20 and 33 of the sediment on weight basis respectively in contrast the range of particle sizes of the cryptotephras detected in this study is finer than 125 m and almost all of the glass shards were finer than 40 m the alkaline and rhyolitic cryptotephras made up only 2 17 and 22 24 respectively of the sediment on weigh basis the high sensitivity of this method stems from the significant difference in trace element contents between the tephras and enclosing hemipelagic sediments in the core alkaline u oki tephra was enriched in ta by one order of magnitude over that of the sediment and depleted in sc by one order the rhyolitic tephra k ah was depleted by about one order in cr relative to that of enclosing the sediment the differences in chemical composition between within plate alkaline tephras and hemipelagic sediments are usually so large that trace element geochemical method is likely to be useful for alkaline cryptotephra detection in other areas with similar tectonic characteristics

sediment fabrics oxygenation history and circulation modes of japan sea during the late quaternary abstract the quaternary hemipelagic sediments of the japan sea are characterized by centimeter to decimeter scale alternations of heavily bioturbated organic poor light layers and finely laminated organic rich dark layers these dark and light layers which can be correlated throughout the deeper part of the basin are considered to reflect changes in bottom water oxygenation however depositional mechanisms responsible for individual dark layers and causes of oxygen depletion are not fully understood two possible settings for deposition of organic rich dark layers are recognized one is a stratified ocean like the black sea where limited vertical advection results in euxinic conditions in the deeper parts of the basin the other is an upwelling region like the arabian sea where the oxygen minimum zone is intensified by enhanced nutrient upwelling and surface productivity in this study fabrics of hemipelagic sediments deposited in the japan sea during the last 160 ka were studied in three cores collected from different latitudes and water depths fabrics were classified into 4 classes based on corresponding bottom water oxygenation level five dark layer types were defined based on the distribution patterns of sediment fabric classes within each dark layer comparison of dark layer types at shallower and deeper sites in a chronologic framework provided evidence for five different modes of deep water circulation these circulation modes which reflect relative intensities of upwelling and density stratification appear to be related to global sea level changes as well as climate impact on the nature of water influx through the tsushima strait

identification of cryptotephra horizons in a north east atlantic marine record spanning marine isotope stages 4 and 5a 60 000 82 000 a b2k abstract tephrochronology is one of the few techniques that offer considerable but as yet largely unrealised potential for the correlation of north atlantic palaeoclimatic archives spanning the mis 4 and 5a substage period a phase of pronounced global cooling during the initiation of the last glacial period in this investigation two previously unidentified rhyolitic tephra horizons believed to be sourced from iceland were isolated within the giant piston core md04 2822 retrieved from the rockall trough north east atlantic one horizon was deposited at the beginning of greenland stadial 19 70 150 a b2k and the other around the cooling transition at the end of greenland interstadial 20 75 320 a b2k density separation epma and la icp ms techniques were utilised for the identification of these cryptotephra within the fine fraction sediment

tropical cyclones cause caco3 undersaturation of coral reef seawater in a high co2 world 1 ocean acidification is the global decline in seawater ph and calcium carbonate caco3 saturation state due to the uptake of anthropogenic co2 by the world s oceans acidification impairs caco3 shell and skeleton construction by marine organisms coral reefs are particularly vulnerable as they are constructed by the caco3 skeletons of corals and other calcifiers we understand relatively little about how coral reefs will respond to ocean acidification in combination with other disturbances such as tropical cyclones seawater carbonate chemistry data collected from two reefs in the florida keys before during and after tropical storm isaac provide the most thorough data to date on how tropical cyclones affect the seawater co2 system of coral reefs tropical storm isaac caused both an immediate and prolonged decline in seawater ph aragonite saturation state was depressed by 1 0 for a full week after the storm impact based on current business as usual co2 emissions scenarios we show that tropical cyclones with high rainfall and runoff can cause periods of undersaturation 1 0 for high mg calcite and aragonite mineral phases at acidification levels before the end of this century week long periods of undersaturation occur for 18 mol high mg calcite after storms by the end of the century in a high co2 world caco3 undersaturation of coral reef seawater will occur as a result of even modest tropical cyclones the expected increase in the strength frequency and rainfall of the most severe tropical cyclones with climate change in combination with ocean acidification will negatively impact the structural persistence of coral reefs

provenance and climate changes inferred from magnetic properties of the sediments from the lower yangtze river china during the last 130 years abstract it is essential to have a clear scientific view on paleoclimate change and its potential environmental and socio economic impacts for the prediction of future climate change fluvial sediment is one of the best archives for the investigations of high resolution environmental variability and anthropogenic impacts on catchment over the last hundreds or even thousands years anthropocene in this study we examine magnetic properties of a 130 year fluvial sediment profile from an island in the main channel of the lower yangtze mainstream which aims to determine the connections between modern observational data and paleoclimate signals from sediments sediments from the upper yangtze river is characterized by high concentration of magnetite which is different from the middle reach the difference of magnetic properties allows us to trace particles in the lower reach back to upstream of the yangtze river climate change that reconstructed from physical properties of sediment susceptibility and mean grain size is comparable to those records in historical documents which provides a possible way to obtain precise ages the calibrated sedimentation rate reflects long term variation of flood drought events over the catchment which is dominantly controlled by the climate circulation of pacific the enhanced human impacts since 1950s especially in the mid lower reaches are observed therefore riverine sediment not only contains paleoclimate information but also reflects human activities

characteristics of the late quaternary tephra layers in the east japan sea and their new occurrences in western ulleung basin sediments abstract the lithologic characteristics stratigraphic relationships and areal distribution of late quaternary tephra layers have been determined based on four piston cores recovered from the western ulleung basin of east japan sea the results show that using morphological and major element compositional data volcanic glass shards dispersed in tephra layers are identical to those of fallout deposits of the ulleung oki ca 9 3 ka aira tanzawa ca 22 ka and ulleung yamato ca 33 ka the lapilli tephra layers ulleung oki and ulleung yamato originating from ulleung island consist predominantly of pumice type glass shards associated with minor amounts of alkali feldspar biotite and plagioclase on the other hand the ash layers including the aira tanzawa ash derived from the japanese islands are mainly composed of bubble wall and or plane type glasses that contain higher sio 2 and lower al 2 o 3 than the lapilli tephra layers the occurrence of tephra layers in the western ulleung basin and their stratigraphic correlation extend the distribution of pumice type glass shards about 50 100 km west of the previously known fallout zone

paleoceanographic changes in the ulleung basin east japan sea during the last 20 000 years evidence from variations in element composition of core sediments a millennial scale paleoceanographic record of the ulleung basin in the southern part of the east japan sea es for the last 20 000 years was reconstructed based on variations in the element compositions of core sediment most of the elements showed relatively wide content ranges throughout the core largely because of different sediment types their grain size spectra biological components and geochemical conditions i e redox conditions in particular biogenic components ca sr ba and caco 3 and some minor elements cu mn mo u cd zn and v revealed three distinct intervals of major paleoceanographic changes interval 1 similar to 18 9 3 kyr bp is characterized by a rhythmic alternation of dark and light colored sediment bands distinctive differences in the abundance of organic carbon carbonate and redox elements between the dark and light colored sediment layers are probably attributable to especially those associated with bottom water redox variations combined with the enhanced primary productivity and water stratification in the ulleung basin

atmospheric co2 stabilization and ocean acidification 1 we use a coupled climate carbon cycle model to examine the consequences of stabilizing atmospheric co2 at different levels for ocean chemistry our simulations show the potential for major damage to at least some ocean ecosystems at atmospheric co2 stabilization levels as low as 450 ppm before the industrial revolution more than 98 of corals reefs were surrounded by waters that were 3 5 times saturated with respect to their skeleton materials aragonite if atmospheric co2 is stabilized at 450 ppm only 8 of existing coral reefs will be surrounded by water with this saturation level also at this co2 level 7 of the ocean south of 60 s will become undersaturated with respect to aragonite and parts of the high latitude ocean will experience a decrease in ph by more than 0 2 units results presented here provide an independent and additional basis for choosing targets of atmospheric co2 stabilization levels

tephra layers of large explosive eruptions of baitoushan changbaishan volcano in the japan sea sediments this paper is based on the results of a comprehensive investigations of sediments from seven cores sampled during the international russian chinese cruise 53 of the r v akademik lavrentyev 2010 in the frames of the russian chinese collaboration between the pacific oceanological institute of the far eastern branch of the russian academy of sciences poi feb ras vladivostok russia and the first institute of oceanography fio qingdao china baitoushan chanbaishan volcano had several powerful explosive eruptions during the middle pleistocene holocene which produced widespread tephra layers the paper reports chemical composition of volcanic glasses and minerals from six tephra layers labeled as b og b sado b j b un1 b v and b tm which belong to baitoushan volcano and were identified in sediments of the northwestern part of the sea of japan the tephras were dated using geochronological data for the host sediments the estimated ages for the middle pleistocene tephra is 488 ka the late pleistocene tephras are 71 1 71 9 cal k b sado 50 8 cal ka b j 38 3 cal ka b un1 and 29 0 29 4 cal ka b v the ash layers consist of alkali rich glass of trachydacitic to alkaline rhyolitic composition and specific assemblage of minerals including fe rich augite hedenbergite aegirine augite aegirine arfvedsonite and fayalite the mineral assemblage is typical for alkalic volcanic rocks from continental rift setting aenigmatite a rare mineral from the group of inosilicates was firstly identified in distal tephra of baitoushan volcano supplied into marine sediments the composition of glasses and minerals from all layers are similar it testifies about steady state conditions of the magma accumulation under baitoushan volcano and about the bimodal character of magmatic chambers during the late pleistocene and holocene since 100 ka

geochemical normalization of magnetic susceptibility for investigation of floodplain sediments magnetic susceptibility ms is commonly used as a proxy for industrial pollution in natural sediments or as a proxy for the percentage of detrital components in peat or carbonates the ms may also reflect the geology of the sediment source and post depositional processes in sediments such as soil development the aim of our research was to test the usefulness of fe normalized mass specific ms and ti normalized fe in a study of floodplain sediments we sampled 27 floodplain sediment cores from several geologically different catchments throughout the czech republic analysed their fe and ti concentrations using x ray fluorescence spectroscopy and determined their to decipher sediment grain size dependence and possible magnetic enrichment background functions for were constructed using similar approach as that used for geochemical background functions of the risk element concentrations with fe concentrations as an independent variable it provides a mechanism to calculate of sediments as it would be pristine i e without post depositional changes and pollution sediments derived from mafic source rocks had fe larger by two orders of magnitude than sediments derived from felsic rocks sediments derived from mafic source rocks also exhibit lower mean fe ti ratio in pristine sediment strata than the average upper continental crust the magnetic carriers inherited from mafic rocks are stepwise destroyed by pedogenesis in the floodplains and thus slowly approach of sediments derived from felsic rocks gleying processes may change fe fe ti ratio allows identifying a past action of those post depositional processes

coral reefs may start dissolving when atmospheric co2 doubles 1 calcification rates in stony corals are expected to decline significantly in the near future due to ocean acidification in this study we provide a global estimate of the decline in calcification of coral reefs as a result of increase in sea surface temperature and partial pressure of co2 this estimate unlike previously reported estimates is based on an empirical rate law developed from field observations for gross community calcification as a function of aragonite degree of saturation arag sea surface temperature and live coral cover calcification rates were calculated for more than 9 000 reef locations using model values of arag and sea surface temperature at different levels of atmospheric co2 the maps we produced show that by the time atmospheric partial pressure of co2 will reach 560 ppm all coral reefs will cease to grow and start to dissolve

paleoclimatic significance of phanerozoic reefs a database of pre quaternary phanerozoic reefs is used to test the significance of ancient reefs as paleoclimatic tracers the compilation of reef paleolatitudes through time and comparison with published paleoclimate curves shows that neither the width of the tropical reef zone nor the total latitudinal range of reefs is correlated with published estimates of paleotemperature however reefs trace paleoclimate indirectly algal reefs tend to prevail during icehouse climatic intervals and distinct high latitude reefs are only developed in cold intervals whereas during greenhouse episodes the reef zone usually ended abruptly at a particular latitudinal boundary in the subtropics additionally different biotic reef types tended to be concentrated in different latitudes the lowest latitudes have usually been occupied by coralline sponge or microbial reefs coral reefs tended to grow in intermediate latitudes and bryozoan reefs constantly occupied the highest latitudinal position

the mechanism of production enhancement in coral reef carbonate systems model and empirical results coral reefs are characterized by enormous carbonate production of the organisms it is known that rapid calcification is linked to photosynthesis under control of the carbonate equilibrium in seawater we have established a model simulating the coexisting states of photosynthesis and calcification in order to examine the effects of photosynthesis and calcification on the carbonate system in seawater supposing that the rates of photosynthesis and calcification are proportional to concentrations of their inorganic carbon source the model calculations indicate that three kinds of unique interactions of the organic and inorganic carbon productions are expected these are photosynthetic enhancement of calcification calcification which benefits photosynthesis and carbonate dissolution induced by respiration the first effect appears when the photosynthetic rate is more than approximately 1 2 larger than that of calcification this effect is caused by the increase of co32 content and carbonate saturation degree in seawater if photosynthesis use molecular carbon dioxide the second effect occurs when the calcification rate is more than approximately 1 6 times larger than that of photosynthesis time series model experiments indicate that photosynthesis and calcification potentially enhance each other and that organic and inorganic carbon is produced more efficiently in the coexisting system than in the isolated reactions these coexisting effects on production enhancement of photosynthesis and calcification are expected to appear not only in the internal pool of organisms but also in a reef environment which is isolated from the outer ocean during low tide according to the measurements on the fringing type shiraho reef in the ryukyu islands the diurnal change of water properties ph total alkalinity total carbon dioxide and carbonate saturation degree were conspicuous this environment offers an appropriate condition for the appearance of these coexisting effects the photosynthetic enhancement of calcification and the respiratory inducement of decalcification were observed during day time and night time slack water periods respectively these coexisting effects especially the photosynthetic enhancement of calcification appear to play important roles for fluorishing coral reef communities

geochemical identification of cryptotephras using inaa from late quaternary hemipelagic sediments southwest japan abstract we present new compositional data on glass shards from cryptotephra layers in five marine sediment cores from the southern japan east sea the hand picked glass shards were extracted from cryptotephra horizons that were distinguished by sem eds for major elements and inaa for trace elements on individual shards most of the glass shards have alkaline and trachyte phonolite compositions and have major and trace element compositions similar to eruptive units on ulleung island stratigraphic inferences indicate the presence of at least four alkaline tephras u 3 post u oki u oki and pre u oki in the interval between the k ah rhyolitic tephra 7 3 cal ka bp and the tl1 regional dark sediment layer 11 8 cal ka bp the new trace elements on glass shards indicate minor compositional distinctions from one visible tephra and four cryptotephras that help to infer fine scale regional correlations the development of a more comprehensive alkaline tephrostratigraphical framework for this region will greatly aid in the reconstruction and chronology of regional stratigraphic variations the recognition of new alkaline cryptotephras in the marine sediments of the japan east sea also contributes towards a better understanding of the volcanic history of ulleung island and nearby seamounts

mineral magnetic properties of a weathering sequence of soils derived from basalt in eastern china abstract the magnetic properties and magnetic mineralogy of a weathering sequence of soils developed on basalt parent material from eastern china were studied by rock magnetism x ray diffraction and soil chemical analyses to establish the connection between mineral magnetic properties and pedogenic development in a subtropical region the magnetic susceptibility of soils formed on basalt varied greatly and did not increase with the degree of pedogenic development the frequency dependent susceptibility fd values of soils ranged from 1 0 to 11 1 and increased with the pedogenic development highly significant linear relationship was found between the frequency dependent susceptibility and the fed content r2 0 683 and fed fet ratio r2 0 780 in soils indicating that pedogenic sp ferrimagnetic grains were associated with enrichment of the secondary iron oxide minerals in the weathering process of soil rock magnetism analysis showed that the major magnetic carriers in the weakly weathered soil profiles are magnetite and or maghemite and the highly developed soil profiles are generally enriched in magnetite maghemite grains of pedogenic origin and the magnetically hard haematite indicating that the magnetic component was transformed from a ferrimagnetic phase magnetite to antiferromagnetic phase hematite during pedogenic development results indicated that some of the magnetic parameters of soils in this case fd can be useful for pedogenic comparisons and age correlations in the weathering sequence of soil it is thus suggested that multiparameter rock magnetic investigations represent a more powerful approach for pedogenesis

the genesis and paleoenvironmental records of longji agricultural terraces southern china a pilot study of human environment interaction ancient agricultural terraces distributed over the mountainous areas in southern china can be taken as new objects for studies on human environment interaction in the past however this type of study is rare this study selected longji terraces longsheng guilin one of the famous ancient agricultural terraces to explore its genesis and paleoenvironmental records three soil profiles including an original hillslope woodland soil profile and two terrace profiles were sampled for analyses of physical and geochemical proxies and radiocarbon dating cultivated soil in the terrace profile shows aggradation making the cultivated horizon a bottom up chronological sedimentary sequence two basal samples in the cultivated horizons of two parallel terrace profiles show calibrated ages of 1361 1406 ad and 1335 1384 ad respectively indicating that the genesis of longji terraces occurred during the late yuan dynasty in chinese history strong survival pressure and desire for new living space in the turbulent social situation of the late yuan dynasty might have been the direct factor forcing some people of national minorities to migrate to the longji mountain area where they effectively utilized the hillslope land and water resources for cultivation by building agricultural terraces and constructing a gravity irrigation network multi proxy analyses of the cultivated horizon of one selected terrace profile reveal that human farming activity has experienced a staged strengthening process including four stages since the late 14th century moreover some changes of the intensity of human farming activity found within each stage might reflect the impact of climatic fluctuations on human farming activity during the little ice age and the later warming period

weathering characteristics of interflow volcanic boles from mandla lobe eastern deccan volcanic province abstract the deccan volcanism straddling the cretaceous paleogene boundary resulted into one of the most extensive continental flood basalts in the western and central peninsular india the interflow sedimentary units boles often cited as paleosols are the rare archives of paleoenvironmental conditions existed during successive lava flows a debate on the origin of boles as true paleosols exists therefore in order to trace out regional extent of such conditions pedogenic non pedogenic in the context of their paleoenvironmental significance during the deccan volcanism we studied here mineral magnetic characteristics of 36 color differentiated bole beds from the mandla lobe in the eastern deccan volcanic province edvp classified into four types gray yellow brown and red based on their munsell notations the gray yellow and brown boles show dominantly ferrimagnetic composition chiefly magnetite and titanomagnetite while red boles characterize mixed ferri and antiferromagnetic mainly hematite mineralogy the granulometric domain parameters suggest larger single domain sd and the multidomain md ferrimagnets in the majority of cases whereas superparamagnetic sp particles with frequency dependent susceptibility fd 2 6 to 20 3 10 8 m 3 kg 1 are limited to the few red and brown boles only the significant presence of primary parent magnetic minerals i e coarse sd md titanomagnetite and magnetite in the majority of boles depict incipient to moderate weathering owing to limited time intervals during successive eruptions the combination of hematite and sp particles present only in the few red and brown boles depicts baking effect rather than pedogenesis the comparison of magnetic properties of boles from edvp and western deccan volcanic province wdvp shows significant differences in the concentration of sp ferrimagnetic particles and hematite attributed to variable weathering intensity duration and heating related alterations from the upper flows both edvp and wdvp boles indicate similar first order paleoenvironmental conditions without any major pedogenesis that can be regionally correlated

magnetic properties of modern soils and quaternary loessic paleosols paleoclimatic implications the magnetic properties of paleosols developed in quaternary sequences of loess have been used for stratigraphic definition correlation with other terrestrial and deep sea sequences and paleoclimatic paleorainfall reconstruction in some loess paleosol sequences including those of the chinese loess plateau tajikistan and the czech republic maxima in magnetic susceptibility values correspond with the paleosol horizons and minima with the least weathered loess layers in other loess soil sequences including those of siberia alaska and argentina the relationship is completely opposite with susceptibility minima associated with the most developed paleosols to account for these opposite relationships the respective roles of 1 magnetic enhancement and 2 magnetic depletion and or dilution in determining soil magnetic properties are investigated for a range of modern soil types most magnetic enhancement is seen in the upper horizons of well drained cambisols absence or loss of magnetic iron oxides is apparent in acid podsol profiles and waterlogged soils for the cambisol profiles significant correlation is found between susceptibility and organic carbon cation exchange capacity and clay content the mineralogy morphology and grain size of soil magnetic carriers extracted from three modern enhanced soils and a paleosol from the chinese loess plateau are also identified by independent petrographic means microscopy and x ray diffraction of magnetic extracts magnetite and maghemite of ultrafine grain size from 0 4 to 0 001 i m are the major contributors to the magnetically enhanced soils weathering can concentrate detrital magnetic grains especially in the fine silt size fractions of soils the magnetic data from the modern soils indicate that interpretation of paleosol magnetic properties must be done on a site specific basis taking into account the possibilities of pedogenic enhancement pedogenic dilution or depletion and allochthonous inputs of magnetic minerals excessively arid wet or acid soils are unable to form significant amounts of pedogenic ferrimagnets well drained intermittently wet dry soils with reasonable buffering capacity and a substrate source of fe show most magnetic enhancement for those soils which favour magnetic enhancement processes correlation has been found between the maximum value of the pedogenic susceptibility and the annual rainfall the almost unique pedogenic system in the chinese loess plateau where variation in soil forming factors other than climate is reduced to a global minimum allows use of the paleo susceptibility values as proxy paleorainfall values to identify the mechanism of any link between magnetic properties for example susceptibility and climate change the mineralogy and grain size of soil magnetic carriers requires detailed investigation given the prospect of 1 quantitative paleorainfall records from continental loess records 2 predictions of present and future climate change and 3 the value of paleoclimate data for testing of numerical climate models such magnetic investigations can contribute significantly to our understanding of past and future environmental change

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

the carbonate chemistry of grand bahama bank waters after 18 years another look major features of the chemistry of northern grand bahama bank waters found in 1981 were similar to those found by broecker and takahashi in 1962 and 1963 measured variations in salinity and extent of caco3 removal are close to the same our findings indicate a more complex salinity distribution on the northern banks probably resulting from transport of high salinity waters from the south and higher pco2 values in the high salinity waters inorganic 14co2 measurements made in this study can be used to calculate very approximate residence times of water on the bank there is general agreement with the values previously determined by broecker and takahashi ship aerial and satellite observations indicate that whitings are not randomly distributed over the bank they form a halo around the northern and western flanks of the high salinity waters s greater than 40 the rate of caco3 removal is about 1 5 times faster in the waters where the whitings are common than in the high salinity waters even though our analytic precision was over 80 times greater than the change predicted in alkalinity if whitings precipitate directly from seawater no differences could be found between whiting and adjacent waters in our opinion the major features responsible for creating whitings controlling their distribution and determining caco3 removal rates on the grand bahama bank remain largely unresolved

revised stratigraphy of holocene tephras on ulleung island south korea and possible correlatives for the u oki tephra abstract detailed field surveys and measurements of major oxide compositions of volcanic glass shards using electron microprobe analyses revealed the stratigraphy of holocene tephras u 4 u 3 and u 2 on ulleung island south korea the bubble wall type glass shards of kikai akahoya k ah tephra detected in soil intercalated with tephra layers indicate that the depositional horizon of the tephra is situated between the u 3 and u 2 tephras this study has established a revised stratigraphy in ascending order of u 4 u 3 k ah and u 2 tephras comparisons of the major chemical compositions and eruption ages of the u 4 and u 3 tephras on ulleung island and those of ulleung tephras detected in and around the japanese islands suggest that these tephras are distributed widely and potentially can serve as useful and important time markers of the early to middle holocene radiocarbon dates and stratigraphic relationships between the k ah and ulleung tephras on the island suggest that the ulleung oki tephra u oki which has been used as an essential time marker of the early holocene is most likely correlated with the u 4 tephra therefore detailed analyses of chemical compositions of glass shards with dating of these tephras are necessary to identify u oki in and around japanese islands

magnetic separation and evaluation of magnetization of brazilian soils from different parent materials abstract ten selected brazilian soils representative of oxisols ultisols alfisols and inceptisols and derived from gneiss basalt sandstone diabase and itabirite were sampled and examined to provide insight into the behavior of their magnetic minerals the objective was to measure the magnetization of the sand silt and clay fractions and to submit the clay fraction to variable magnetic fields to obtain the magnetization curves and to study their magnetic behavior as related to their parent material lithology the separation procedure using a magnetic separator was done in two different ways dry separation for the sand and wet separation for the silt and clay fractions x ray diffraction patterns of magnetic and nonmagnetic fractions were obtained and the segregation of ferrimagnetic minerals were shown the magnetization s of the total and the magnetic and nonmagnetic soil fractions was evaluated using a special analytical balance the s values obtained varied from 0 03 to 17 72 j t 1 kg 1 for sand 0 05 to 8 91 j t 1 kg 1 for silt and 0 05 to 2 54 j t 1 kg 1 for the clay fractions the results from the magnetically concentrated fractions varied in the same fashion but reached higher values magnetization curves showed spontaneous magnetization ms values of 0 6 to 3 35 j t 1 kg 1 high field slopes ranging from 0 17 to 0 77 j t 2 kg 1 and clearly the influence of the parent material lithology on the nature of the soil magnetic behavior magnetic measurements suggested pathways for ferrimagnetic minerals transformations in soil systems

land ocean linkages over orbital and millennial timescales recorded in late quaternary sediments of the japan sea late quaternary sediments of the japan sea are characterized by centimeter to meter scale alternations of dark and light layers which are synchronous basinwide high resolution analyses of the sediments from ocean drilling program site 797 reveal that deposition of the meter scale alternations reflect variations in paleoceanographic conditions which were closely associated with glacio eustatic sea level changes through the modulation of the volume and character of the influx to the sea through the tsushima strait the centimeter to decimeter scale alternations reflect millennial scale variations which are possibly associated with dansgaard oeschger d o cycles with each dark layer appearing to correspond to an interstadial this variability is attributed to the development of a humid climate in central to eastern asia and the consequent increase in discharge from the huanghe and changjiang rivers during interstadials this caused expansion of the east china sea coastal water ecscw which penetrated more strongly into the japan sea the increased influence of the lower salinity nutrient enriched ecscw reduced deep water ventilation and enhanced the surface productivity leading to the development of anoxic bottom waters and deposition of the dark layers thus the centimeter to decimeter scale alternations of the dark and light layers record wet and dry cycles in central to eastern asia possibly associated with d o cycles

a continuous 5300 yr holocene cryptotephrostratigraphic record from northern new zealand and implications for tephrochronology and volcanic hazard assessment a continuous 5280 calendar cal yr long cryptotephrostratigraphic record of a peat core from northern new zealand demonstrates that cryptotephra studies can enhance conventional tephra records by extending the known distribution of ash fall and enabling re assessment of volcanic hazards a systematic sampling strategy was used to locate peaks in glass shard concentrations and to determine loci of individual geochemical populations and a palynological method involving spiking samples with lycopodium spores was adapted to facilitate accurate counting of glass shard concentrations using glass shard major element compositions and a core chronology based on eight ams 14c ages and two visible macroscopic tephra layers taupo tephra unit y 1688 1748 cal bp and tuhua tephra 6800 7230 cal bp 2cr age ranges four cryptotephras were correlated with known eruptions whakaipo unit v 2743 2782 cal bp stent unit q 4240 4510 cal bp and unit k 4970 5290 cal bp erupted from taupo volcanic ce

identification of the late quaternary tephra layers in the ulleung basin of the east sea using geochemical and statistical methods abstract the late quaternary tephra layers discovered in piston cores from the ulleung basin of the east sea sea of japan were studied using x ray fluorescence spectrometry xrf inductively coupled plasma atomic emission icp aes and inductively coupled plasma mass spectrometer icp ms in order to identify and differentiate the tephra layers and to characterize their major and trace element compositions the morphology and geochemistry of glass shards combined with 14c dating and statistical methods confirm the ulleung and aira tanzawa eruptions as the origin of the tephra layers respectively the so called ulleung oki u oki 10 1 cal ka and ulleung yamato u ym 30 9 cal ka tephra layers consist predominantly of pumice type glass shards in contrast the aira tanzawa at 23 cal ka tephra layer consists mainly of plane type and or bubble wall glass shards the u oki and u ym tephra layers contain k rich glasses r k2o sio2 0 09 ranging from phonolitic to trachytic alkali compositions whereas the at tephra layer which contains k poor glasses r ca 0 04 is rhyolitic according to trace element content the relative amounts of the elements ti zr y nb and p from the tephra layers evidently indicate the different tectonic zones between the ulleung back arc and kyushu island arc islands especially the relatively depleted concentrations of feo v co and ni in the u oki tephra layer most likely reflect more fractional crystallization of olivine pyroxene hornblende and magnetite than those in the u ym tephra layer

increase of atmospheric co2 during deglaciation constraints on the coral reef hypothesis from patterns of deposition 1 the coral reef hypothesis asserts that carbonate production on newly flooded shelves contributes importantly to the rise of atmospheric carbon dioxide during deglaciation we seek to constrain the timing and strength of such carbon dioxide flux by re assessing reef and platform distribution in the world ocean the pattern of reef growth that emerges suggests that emission of co 2 resulting from carbonate production was important particularly during the late stages of deglaciation the effect peaked during the early holocene and presumably contributed to the warming in the climatic optimum

coral reef calcification and climate change the effect of ocean warming 1 coral reefs are constructed of calcium carbonate caco3 deposition of caco3 calcification by corals and other reef organisms is controlled by the saturation state of caco3 in seawater and sea surface temperature sst previous studies have neglected the effects of ocean warming in predicting future coral reef calcification rates in this study we take into account both these effects by combining empirical relationships between coral calcification rate and and sst with output from a climate model to predict changes in coral reef calcification rates our analysis suggests that annual average coral reef calcification rate will increase with future ocean warming and eventually exceed pre industrial rates by about 35 by 2100 our results suggest that present coral reef calcification rates are equivalent to levels in the late 19th century and does not support previous suggestions of large and potentially catastrophic decreases in the future

sakurajima satsuma sz s and noike yumugi n ym tephras new tephrochronological marker beds for the last deglaciation southern kyushu japan abstract two prominent tephras sakurajima satsuma sz s erupted from sakurajima volcano and noike yumugi n ym erupted from kuchierabujima island provide new key marker beds for dating and synchronizing palaeoenvironmental and archaeological records in the last deglaciation in southern japan these tephras were identified on the basis of glass major element compositions in two distal areas a marine core images md982195 in the northern part of the east china sea and on the central part of tanegashima island and we related their stratigraphic positions to the marine oxygen isotope based chronology in md982195 sz s 0 8 cm in thickness at 9 12 m depth and n ym 3 cm in thickness at 9 30 m depth are both white vitric ash grade tephras on tanegashima island sz s 10 cm in thickness and n ym 3 cm in thickness are stratigraphically constrained by well characterised marker tephras kikai akahoya 7300 cal bp and aira tn 29 000 cal bp sz s is rhyolitic and homogeneous on the basis of glass major element compositions assayed by electron microprobe pumiceous glass shards predominant in distal sz s tephra indicate that it derived from pumice fall units that correspond to pumiceous and phreatomagmatic fine ash units constituting proximal sz s tephra n ym is rhyolitic and glass major element analyses reveal compositional diversity between units suggesting that the lower and middle tephra units dispersed to the east whereas the upper unit was dispersed north to northwest from the vent stratigraphically sz s occurs at around the start of the late glacial reversal cooling in oxygen isotope records of md982195 corresponding to the end of gi 1 and the start of gs 1 in the ice core events of ngrip gicc05 consistent with a terrestrial age of 12 800 cal bp based on the oxygen isotope stratigraphy the tephra identified in the core as n ym at 9 30 m depth is close to the end of greenland gi 1 and hence has an age of 13 000 cal bp but on kuchierabujima island it has an age based on 14 c assay of charcoal of c 14 900 cal bp although this age discrepancy 14 9 vs 13 0 cal ka needs resolution the occurrence in core md982195 of n ym shows that it is more widespread than hitherto demonstrated the widespread distributions and key stratigraphic positions for the two marker tephras indicate that they are thus critical isochrons for precise correlation of palaeoenvironmental changes and prehistoric cultural events during the last deglaciation in southern kyushu and for relating such changes and events to the ice core chronology via the marine oxygen isotope chronostratigraphy

magnetic susceptibility of soils in different slope positions in saskatchewan canada abstract the magnetic susceptibility of soils varies with the slope position due to some factors such as texture and drainage class this study attempts to link to soil profile characteristics soil horizon type organic and inorganic c sand and oxalate feo and dithionite fed extractable iron measured on soil cores collected from the three uncultivated soil catenas in saskatchewan the parent material at all sites consisted of medium textured hummocky glacial till the waitville catena gray luvisol was developed under trees the weyburn catena dark brown chernozem under grass and the oxbow catena black chernozem had trees on the lower slope and grass in the center of the depression and on the upper and middle slopes in all the three catenas a downslope decrease in was correlated with increasing feo fed ratios and decreasing sand content lower slope gleyed profiles in the two chernozemic catenas had high feo fed ratios and low the impact of gleying was most evident in the solum and tended to increase in the c horizons of these profiles the of the sand and silt fractions was positively correlated with that of the bulk soil whereas the of the clay fraction did not vary with the of the bulk soil stable sand sized magnetite grains are believed to be rare in these soils

towards rapid assay of cryptotephra in peat cores review and evaluation of various methods abstract peat bogs are highly effective archives for the preservation and detection of cryptotephra but the conventional methods used to detect these hidden diminutive layers are destructive and can be time consuming we briefly review methods that have been used for cryptotephra detection and evaluate the potential of a range of alternative reconnaissance methods both non destructive and destructive to provide for more rapid examination of continuous cryptotephra content in peat cores the techniques evaluated magnetic susceptibility ms spectrophotometry and x ray fluorescence are used to pick out compositional contrasts between tephra deposits and peat measurements of organic content are also evaluated as a potential guide to tephra content based on an inverse relationship although we find limitations to each method particularly where deployed at the distal most end of tephra dispersal there is potential for all methods to be used in the detection of cryptotephra where time or material is limited these methods can also provide additional sedimentological and stratigraphic information for studies of peat cores however where a reliable cryptotephra profile is required we conclude that there is no quick or easy substitute for the conventional extraction microscopy method

fingerprints and age models for widespread new zealand tephra marker beds erupted since 30 000 years ago a framework for nz intimate abstract the role of tephras in the nz intimate project is a critical one because most high resolution palaeoclimatic records are linked and dated by one or more tephra layers in this review first we document eruptive distributional and compositional fingerprinting data both mineralogical and geochemical for 22 key marker tephras erupted since 30 000 years ago to facilitate their identification and correlation we include new glass compositional data the selected marker tephras comprise 10 from taupo and nine from okataina volcanoes rhyolitic one from tuhua volcano peralkaline rhyolitic and one each from tongariro and egmont volcanoes andesitic second we use four approaches to develop 2 age models for the tephras youngest to oldest 1 calendar ages for kaharoa and taupo y were obtained by wiggle matching log derived tree ring sequences dated by 14c 2 whakaipo v was dated using an age depth model from peat 3 14 tephras in the montane kaipo peat sequence waimihia s unit k whakatane tuhua mamaku rotoma opepe e poronui c karapiti b okupata konini waiohau rotorua rerewhakaaitu were dated by simultaneously wiggle matching stratigraphic position and 51 independent 14c age points against intcal04 using bayesian probability methods via both oxcal and bpeat and 4 the five oldest tephras erupted before ca 18 000 cal yr bp were dated by calibrating limited numbers of 14c ages using intcal04 okareka or comparison curves of the expanded cariaco basin sequence te rere kawakawa oruanui poihipi okaia kawakawa oruanui tephra the most widely distributed marker tephra was erupted probably ca 27 097 957 cal yr bp potential dating approaches for the older tephras include their identification in antarctic ice cores if present or annually laminated sediments for which robust calendar age models have been constructed high precision ams 14c dating on appropriate material from environmentally stable sites systematic luminescence dating or new radiometric techniques e g u th he if suitable minerals are available and errors markedly reduced further application of bayesian age modelling to stratigraphic sequences of 14c ages possibly augmented with luminescence ages may help refine age models for pre holocene tephras with the largest errors finally we discuss the critical role these marker tephras play in the ongoing construction of an event stratigraphy for the new zealand region which is a key objective of australasian and southern hemisphere intimate projects